Search results for: Kang Lin Peng

Authors: Han-Seul Lee, Min-Koo Kang, Sang-Ill Lee

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This study was conducted to reduce runoff by rainwater infiltration facility using attached growth with Bacillus sp., which are reported to remove nitrogen and phosphorus, as well as organic matter effectively. This study was investigated non-point pollutants removal efficiency of organic, nitrogen, and phosphorus in column using the media attached growth with Bacillus sp. To compare attached growth with bacillus sp. and detached media, two columns filled with perlite, zeolite, vermiculite, pumice, peat-moss was installed. In A column (attached growth with bacillus sp.), in case of infiltration velocity 30 mm/hr in high concentration of influent, it showed the removal efficiency (after aging term) is SS (suspended solid) 85.8±1.2 %, T-P (total phosphorus) 67.0±8.1 %, T-N (total nitrogen) 66.0±4.9 %, COD (chemical oxygen demand) 73.6±2.9 %, NH4+-N 72.7±3.0 %. In B column (detached media), in case of infiltration velocity 30 mm/hr in high concentration of influent, it showed the removal efficiency (after aging term) is SS 86.0±2.2 %, T-P 62.5±11.3 %, T-N 53.3±3.9 %, COD 34.6±3.7 %, NH4+-N 61.5±2.8 %. Removal efficiency of A column is better than B column. As the result from this study, using media with Bacillus sp. can improve an effective removal of non-point source pollutants.

Keywords: non-point source pollutants, Bacillus sp., rainwater, infiltration facility

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Authors: Minsung Kim, Hyunkoo Kang, Jinkoo Kim

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In this study, a hybrid energy dissipation device is developed by combining a steel slit plate and friction pads to be used for seismic retrofit of structures, and its effectiveness is investigated by comparing the life cycle costs of the structure before and after the retrofit. The seismic energy dissipation capability of the dampers is confirmed by cyclic loading tests. The probabilities of reaching various damage states are obtained by fragility analysis, and the life cycle costs of the model structures are computed using the PACT (Performance Assessment Calculation Tool) program based on FEMA P-58 methodology. The fragility analysis shows that the probabilities of reaching limit states are minimized by the seismic retrofit with hybrid dampers and increasing column size. The seismic retrofit with increasing column size and hybrid dampers results in the lowest repair cost and shortest repair time. This research was supported by a grant (13AUDP-B066083-01) from Architecture & Urban Development Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

Keywords: FEMA P-58, friction dampers, life cycle cost, seismic retrofit

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Authors: Gurmeet Singh Cheema, Gurjinder Singh, Amardeep Singh Kang

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Aluminium alloy 6061 is a medium to high strength heat-treatable alloy which has very good corrosion resistance and very good weldability. Friction Stir Welding was developed and this technique has attracted considerable interest from the aerospace and automotive industries since it is able to produce defect free joints particularly for light metals i.e aluminum alloy and magnesium alloy. In the friction stir welding process, welding parameters such as tool rotational speed, welding speed and tool shoulder diameter play a major role in deciding the weld quality. In this research work, an attempt has been made to understand the effect of tool rotational speed, welding speed and tool shoulder diameter on friction stir welded AA6061 aluminium alloy joints. Statistical tool such as central composite design is used to develop the mathematical relationships. The mathematical model was developed to predict mechanical properties of friction stir welded aluminium alloy joints at the 95% confidence level.

Keywords: aluminium alloy, friction stir welding, central composite design, mathematical relationship

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Authors: H. G. Noh, H. G. Park, B. S. Kang, J. Kim

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Electromagnetic forming process (EMF) is one of high-velocity forming processes using Lorentz force. Advantages of EMF are summarized as improvement of formability, reduction in wrinkling, non-contact forming. In this study, numerical simulations were conducted to determine the practical parameters for EMF process. A 2-D axis-symmetric electromagnetic model was considered based on the spiral type forming coil. In the numerical simulation, RLC circuit coupled with spiral coil was made to consider the design parameters such as system input current and electromagnetic force. In order to deform the sheet in the patter shape die, two types of spiral shape coil were considered to deform the pattern shape sheet. One is a spiral coil that has 6turns with dead zone at centre point. Another is a normal spiral coil without dead zone that has 8 turns. In the electric analysis, input current and magnetic force were compared and then plastic deformation was treated in the mechanical analysis for two coil cases. Deformation behaviour of dead zone coil case has good agreement with pattern shape die. As a result, deformation behaviour could be controlled by giving dead zone at centre of the coil in spiral shape coil case.

Keywords: electromagnetic forming, spiral coil, Lorentz force, manufacturing

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Authors: Li Mengmeng, Kang Jian

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With the rapid development of the city, the noise pollution becomes more and more serious. Noise has seriously affected people's normal life, study and work. In addition, noise has seriously affected the city's ecological environment and the migration of birds. Therefore, it is urgent to control the noise. As one of natural noise-reducing materials, plants have been paid more and more attention. In urban landscape design, it is very important to choose plant species with good noise reduction effect to the sustainable development of urban ecology. The aim of this paper is to find out the characteristics of the plant with good noise reduction effect and apply it in urban landscape design. This study investigated the vibration of leaves of six plant species in a sound field using a Keyence (IG-1000/CCD) Laser Micrometer. The results of the experiments showed that the vibration speed of plant leaves increased obviously after being stimulated by sound source, about 5-10 times. In addition, when driven by the same sound, the speed of all leaves varied with the difference of leaf thickness, leaf size and leaf mass. The speed of all leaves would increase with the increase of leaf size and leaf mass, while those would decrease with the increase of leaf thickness.

Keywords: landscape design, leaf vibration , noise attenuation, plants configuration

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Authors: Zhipeng Chen, Peng Zhang, Qingyun Liu, Li Guo

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With the Internet becoming the dominant channel for business and life, many IPs are increasingly masked using web proxies for illegal purposes such as propagating malware, impersonate phishing pages to steal sensitive data or redirect victims to other malicious targets. Moreover, as Internet traffic continues to grow in size and complexity, it has become an increasingly challenging task to detect the proxy service due to their dynamic update and high anonymity. In this paper, we present an approach based on behavioral graph analysis to study the behavior similarity of web proxy users. Specifically, we use bipartite graphs to model host communications from network traffic and build one-mode projections of bipartite graphs for discovering social-behavior similarity of web proxy users. Based on the similarity matrices of end-users from the derived one-mode projection graphs, we apply a simple yet effective spectral clustering algorithm to discover the inherent web proxy users behavior clusters. The web proxy URL may vary from time to time. Still, the inherent interest would not. So, based on the intuition, by dint of our private tools implemented by WebDriver, we examine whether the top URLs visited by the web proxy users are web proxies. Our experiment results based on real datasets show that the behavior clusters not only reduce the number of URLs analysis but also provide an effective way to detect the web proxies, especially for the unknown web proxies.

Keywords: bipartite graph, one-mode projection, clustering, web proxy detection

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Authors: Seongryong Kang, Woonjin Kim, Sungjoo Lee

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Under the environment of fierce competition and globalized economy, international technology collaboration has gained increasing attention as a way to improve innovation efficiency. While international technology transfer helps a firm to acquire necessary technology in a short period of time, it also has a risk; embedding external technology from overseas partners may cause a transaction cost due to the regional, cultural and language barriers, which tend to offset the benefits of such transfer. Though a number of previous studies have focused on the effects of technology in-transfer on firm performance, few have conducted in the context of international technology transfer. To fill this gap, this study aims to investigate the impact of international technology in-transfer on firm performance – both innovation and financial performance, with a particular emphasis on the diversity and intensity of such transfer. To do this, we adopted technology balance payment (TBP) data of Korean firms from 2010 to 2011, where an intermediate regression analysis was used to identify the intermediate effects of absorptive capacity. The analysis results indicate that i) the diversity and intensity of international technology transfer influence innovation performance by improving R&D capability positively; and ii) the diversity has a positive impact but the intensity has a negative impact on financial performance through the intermediation of R&D intensity. The research findings are expected to provide meaningful implications for establishing global technology strategy and developing policy programs to facilitate technology transfer.

Keywords: diversity, intensity, international technology acquisition, performance, technology transfer

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Authors: Soyeon Kang, Youn-Jee Chung, Jung Namkung

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Objective: This retrospective study investigated the association between uric acid level and bone mineral density (BMD) in the postmenopausal period. Methods: The study included 328 menopausal women (mean age, 57.3 ± 6.5 years; mean serum uric acid level, 4.6 ± 1.0 mg/dL). Patients were divided into three groups by tertile of serum uric acid level. Patients who used hormone treatment (HT), bisphosphonates, or lipid-lowering agents were included. Results: Blood urea nitrogen, serum creatinine, and serum triglyceride levels were significantly higher in the upper uric acid tertiles. No significant difference was found in the mean uric acid levels between medication users and non-users. Distinct HT regimens showed different mean serum uric acid levels. In a cross-sectional analysis, higher serum uric acid levels showed a tendency toward increased BMD in the spine and femoral neck. Longitudinal analysis of 186 women who underwent follow-up examination at a mean interval of 14.6 months revealed a trend toward a smaller reduction in femoral neck BMD in women in the upper serum uric acid tertiles. Conclusion: A positive correlation exists between serum uric acid levels and BMD in menopausal women.

Keywords: menopause, antioxidant, uric acid, bone mineral density

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Authors: Bingjie Wang, Su-Yeon Kwon, Ik-Joong Kang

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A Surface-enhanced Raman Scattering (SERS) as the principle for enhancing Raman scattering by molecules adsorbed on rough metal surfaces or by nanostructures is used to detect the concentration change of γ-Aminobutyric Acid (GABA). As for the gold-chitosan nanoshell, it is made by using chitosan nanoparticles crosslinking with sodium tripolyphosphate(TPP) for the first step to form the chitosan nanoparticles, which would be covered with the gold sequentially. The size of the fabricated product was around 100nm. Based on the method that the sulfur end of the MPA linked to gold can form the very strong S–Au bond, and the carboxyl group, the other end of the MPA, can easily absorb the GABA. GABA is the mainly inhibitory neurotransmitter in the mammalian central nervous system in the human body. It plays such significant role in reducing neuronal excitability throughout the nervous system. When the system formed, it generated SERS, which made a clear difference in the intensity of Raman scattering within the range of GABA concentration. So it is obtained from the experiment that the calibration curve according to the GABA concentration relevant with the SERS scattering. In this study, DLS, SEM, FT-IR, UV, SERS were used to analyze the products to obtain the conclusion.

Keywords: chitosan-gold nanoshell, mercaptopropionic acid, γ-aminobutyric acid, surface-enhanced Raman scattering

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Authors: Jeong Hong Kim, Ju Wan Kang

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Objective: Histamine skin prick testing is most commonly used to diagnose immunoglobulin E (IgE)-mediated allergic diseases, and histamine reactivity is used as a standardized positive control in the interpretation of a skin prick test. However, reactivity to histamine differs among individuals for reasons that are poorly understood. The present study aimed to evaluate the potential association between body mass index (BMI) and histamine skin reactivity in children. Methods: A total of 451 children (246 boys, 205 girls) aged 7–8 years were enrolled in this study. The skin prick test was performed with 26 aeroallergens commonly found in Korea. Other information was collected, including sex, age, BMI, parental allergy history, and parental smoking status. Multivariate analysis was used to confirm the association between histamine skin reactivity and BMI. Results: The histamine wheal size was revealed to be associated with BMI (Spearman's Rho 0.161, p < 0.001). This association was confirmed by multivariate analysis, after adjusting for sex, age, parental allergy history, parental smoking status, and allergic sensitization (coefficient B 0.071, 95% confidence interval 0.030–0.112). Conclusions: Skin responses to histamine were primarily correlated with increased BMI. Further studies are needed to understand the clinical implication of BMI when interpreting the results of skin prick test.

Keywords: allergy, body mass index, histamine, skin prick test

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Authors: Zhou Xiong, Kang Shao Bo, Yang Bo

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To date, high-performance structural steel has been widely used for columns in construction practices due to its significant advantages over conventional steel. However, the same design approach with conventional steel columns is still adopted in the design of high-performance steel columns. As a result, its superior properties cannot be fully considered in design. This paper conducts a test and finite element analysis on the overall stability behaviour of welded Q460GJ steel box columns. In the test, four steel columns with different slenderness and width-to-thickness ratio were compressed under an axial compression testing machine. And finite element models were established in which material nonlinearity and residual stress distributions of test columns were included. Then, comparisons were made between test results and finite element result, it showed that finite element analysis results are agree well with the test result. It means that the test and finite element model are reliable. Then, we compared the test result with the design value calculated by current code, the result showed that Q460GJ steel box columns have the higher overall buckling capacity than the design value. It is necessary to update the design curves for Q460GJ steel columns so that the overall stability capacity of Q460GJ box columns can be designed appropriately.

Keywords: axial compression, box columns, global buckling, numerical simulations, Q460GJ steel

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Authors: Jinhyun Ryu, Chengliang Xie, Nal Ae Yoon, Dong Hoon Lee, Gu Seob Roh, Hyun Joon Kim, Gyeong Jae Cho, Wan Sung Choi, Sang Soo Kang

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Type 2 diabetes is a heterogeneous group of metabolic disorders featured by a deficit in or loss of insulin activity to maintain normal glucose homeostasis. Mainly, it results from the compromised insulin secretion and/or reduced insulin activity. The frequency of type 2 diabetes (T2D) has been increased rapidly in recent decades with the increase in the trend of obesity due to life style and food habit. Obesity is considered to be the primary risk factor for the development of insulin resistance and thereby developing T2D. Traditionally naturally occurring fruits, vegetables etc. are being used to treat many pathogenic conditions. In this study, we tried to find out the effect of a popularly used vegetable in Bangladesh and several other Asian countries, ‘bitter melon’ on high fat diet induced T2D. To investigate the effect, we used 70% ethanol extract of bitter melon (BME) as dietary supplement with chow. BME was found to attenuate the high fat diet (HFD) induced body weight and total fat mass significantly. We also observed that BME reduced the insulin resistance induced by HFD effectively. Furthermore, dietary supplementation of BME was highly effective in increasing insulin sensitivity, and reducing the hepatic fat and obesity. These results indicate that BME could be effective to attenuate T2D and could be a preventive measure against T2D.

Keywords: bitter melon, obesity, type 2 diabetes, high fat diet

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Authors: Dilin Chen, Kang Luo, Jian Wu, Chun Yang, Hongliang Yi

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Electrically driven flows (EDF) systems play an important role in fuel cells, electrochemistry, bioseparation technology, fluid pumping, and microswimmers. The core scientific problem is multifield coupling, the further development of which depends on the exploration of nonlinear instabilities, force competing mechanisms, and energy budgets. In our study, two categories of electrostatic force-dominated phenomena, induced charge electrosmosis (ICEO) and ion conduction pumping are investigated while considering polymer rheological characteristics and heat gradients. With finite volume methods, the thermal modulation strategy of ICEO under the thermal buoyancy force is numerically analyzed, and the electroelastic instability turn associated with polymer addition is extended. The results reveal that the thermal buoyancy forces are sufficient to create typical thermogravitational convection in competition with electroconvective modes. Electroelastic instability tends to be promoted by weak electrical forces, and polymers effectively alter the unstable transition routes. Our letter paves the way for improved mixing and heat transmission in microdevices, as well as insights into the non-Newtonian nature of electrohydrodynamic dynamics.

Keywords: non-Newtonian fluid, electroosmotic flow, electrohydrodynamic, viscoelastic liquids, heat transfer

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Authors: Sang Guen Kim, Sib Sankar Giri, Jin Woo Jun, Saekil Yun, Hyoun Joong Kim, Sang Wha Kim, Jung Woo Kang, Se Jin Han, Se Chang Park

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Emerging of the super bacteria, bacteriophages are considered to be as an alternative to antibiotics. As the demand of phage increased, economical and large production of phage is becoming one of the critical points. For the therapeutic use, what is important is to eradicate the pathogenic bacteria as fast as possible, so higher concentration of phages is generally needed for effective therapeutic function. On the contrary, for the maximum production, bacteria work as a phage producing factory. As a microbial cell factory, bacteria is needed to last longer producing the phages without eradication. Consequently, killing the bacteria fast has a negative effect on large production. In this study, Multiplicity of Infection (MOI) was manipulated based on initial bacterial inoculation and used phage pAh-6C which has therapeutic effect against Aeromonas hydrophila. 1, 5 and 10 percent of overnight bacterial culture was inoculated and each bacterial culture was co-cultured with the phage of which MOI of 0.01, 0.0001, and 0.000001 respectively. Simply changing the initial MOI as well as bacterial inoculation concentration has regulated the production quantity of the phage without any other changes to culture conditions. It is anticipated that this result can be used as a foundational data for mass production of lytic bacteriophages which can be used as the therapeutic bio-control agent.

Keywords: bacteriophage, multiplicity of infection, optimization, Aeromonas hydrophila

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Authors: Mi Ok Kang

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This study examined the influences of including LGBTQ-related content in a multicultural teacher education course on the development of prospective teachers’ social justice identities. Appling a content analysis to 53 reflection texts written by participating prospective teachers in response to the relevant course content, this study deduced the stages of social justice identity development (naïve, acceptance, resistance, redefinition, and internalization) that participants reached during the course. The analysis demonstrated that the participants reached various stages in the social identity development model and none of the participants remained at the naïve stage during/after class. The majority (53%) of the participants reached the internalization stage during the coursework and became conscious about the heterosexual privileges they have had and aware of possible impacts of such privilege on their future LGBTQ students. Also the participants had begun to develop pedagogic action plans and devised applicable teaching strategies for their future students based on the new understanding of heteronormativity. We expect this study will benefit teacher educators and educational administrators who want to address LGBTQ-related issues in their multicultural education programs and/or revisit the goals, directions, and implications of their approach.

Keywords: LGBTQ, heteronormativity, social justice identity, teacher education, multicultural education, content analysis

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Authors: Heeyong Noh, Seongryong Kang, Sungjoo Lee

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As the world becomes increasingly interconnected, firms have tried to explore market opportunities not only in the domestic market but also abroad. In particular, transactions of intangible assets in the global market now take on great importance. Accordingly, technology transfer activities such as patent licensing, copyright transfer, or workforce trainings which are considered significant to leverage an organization’s internal capabilities, are occurring more frequently and briskly across the world than ever before. Though a number of studies have addressed the issues regarding technology transfer, most of them have focused on university-industry technology transfer. Of course, some have investigated international technology transfer phenomenon but used patent citations data as a proxy. In order to understand the phenomena more clearly, it would be necessary to collect and analyze data that can measure technology transfer activities between firms more directly. Therefore, this study aims to examine the patterns of international trade in technology by employing data about international technology in-licensing activities in Korean firms. We also investigate the effect of international technology in-licensing strategy on a firm’s innovation performance. The research findings are expected to help R&D managers understand how firms have absorbed technological knowledge from foreign firms in the form of licensing and further develop effective international collaboration strategies. In addition, significant implications can be offered for political decision-making regarding technology trade within increasing international interconnections.

Keywords: international technology trade, technology trade effect, technology transfer, R&D managers

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Authors: Da LI, Peng Xu

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Recent extreme weather events, such as the 2021 European floods and North American heatwaves, have exposed the vulnerability of energy systems to both extreme demand scenarios and potential physical damage. Current integrated energy system designs often overlook performance under these challenging conditions. This research, focusing on a regional integrated energy system in Ningbo, China, proposes a distinct design method to optimize system reliability during extreme events. A multi-scenario model was developed, encompassing various extreme load conditions and potential system damages caused by severe weather. Based on this model, a comprehensive reliability improvement scheme was designed, incorporating a gradient approach to address different levels of disaster severity through the integration of advanced technologies like distributed energy storage. The scheme's effectiveness was validated through Monte Carlo simulations. Results demonstrate significant enhancements in energy supply reliability and peak load reduction capability under extreme scenarios. The findings provide several insights for improving energy system adaptability in the face of climate-induced challenges, offering valuable references for building reliable energy infrastructure capable of withstanding both extreme demands and physical threats across a spectrum of disaster intensities.

Keywords: extreme weather events, integrated energy systems, reliability improvement, climate change adaptation

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Authors: Dong Jin Kang

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Application of single board microcontrollers is an important skill even for non-electronic engineering major students. Arduino board is widely utilized in engineering classes of the Yeungnam University of South Korea. In those classes, students are subjected to learn how to use various sensor components related to motion, sound, light, and so on as well as physical quantities. Students are grouped into several teams, and each team consists of 4~5 students. Many students are not motivated enough to learn those skills. An extracurricular program was planned to improve this problem. The extracurricular program was held as an international boot camp where students from three different countries were invited to participate. 10 students groups were formed, and each team was consisted of students having different nationality. The camp was 4 days long and wrapped up with competitions. During the camp, every student was assigned to design and make a two wheel robot. The competition was carried out in two different areas; individual and group performances. As most skills dealt in the class are used to build the robot, students are much motivated to review the whole subjects of the class. All students were surveyed after the program. The survey shows that the skills studied in the class are greatly improved, and practically understood. Staying at the dormitory and teaming with international students are help students improve communication skills. Competition at the camp was found as a key element to inspire and attract students for voluntary participation.

Keywords: extracurricular program, robot, Arduino board, international camp, competition

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Authors: Yeonjune Kang

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A triangulation of a planar region is a partition of that region into triangles. In the finite element method, triangulations are often used as the grid underlying a computation. In order to be suitable as a finite element mesh, a triangulation must have well-shaped triangles, according to criteria that depend on the details of the particular problem. For instance, most methods require that all triangles be small and as close to the equilateral shape as possible. Stated differently, one wants to avoid having either thin or flat triangles in the triangulation. There are many triangulation procedures, a particular one being the one known as the longest edge bisection algorithm described below. Starting with a given triangle, locate the midpoint of the longest edge and join it to the opposite vertex of the triangle. Two smaller triangles are formed; apply the same bisection procedure to each of these triangles. Continuing in this manner after n steps one obtains a triangulation of the initial triangle into 2n smaller triangles. The longest edge algorithm was first considered in the late 70’s. It was shown by various authors that this triangulation has the desirable properties for the finite element method: independently of the number of iterations the angles of these triangles cannot get too small; moreover, the size of the triangles decays exponentially. In the present paper we consider a related triangulation algorithm we refer to as the largest angle bisection procedure. As the name suggests, rather than bisecting the longest edge, at each step we bisect the largest angle. We study the properties of the resulting triangulation and prove that, while the general behavior resembles the one in the longest edge bisection algorithm, there are several notable differences as well.

Keywords: angle bisectors, geometry, triangulation, applied mathematics

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Authors: Kang-Hyun Leem, Myung-Gyou Kim, Hye Kyung Kim

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Velvet antler (VA), the immature antlers of male deer, is traditionally used for thousands of years in Asian countries, such as Korea, China, Taiwan, and Mongolia. It has been considered to improve immune system and physical strength. The goal of this study was to investigate the immunomodulatory effect of deer antler velvet using in vitro system. In the first step, the effects of VA (70% ethanol extract) on the proliferation of splenocytes, bone marrow cell, and macrophages were determined. Next, the effect of VA on the production of nitric oxide and phagocytic activity in macrophage were measured. The results showed that VA treatment increased concanavalin-A stimulated splenocyte, bone marrow cells, and macrophage proliferation in a dose dependent manner. VA at 50 and 100 ug/mL concentrations significantly enhanced the concanavalin-A stimulated splenocyte proliferation by 8.8% and 18.5%, respectively. The proliferation of bone marrow cells, isolated from 5wk-old ICR mice, were increased by 25.2% and 46.5% by 50 and 100 ug/mL VA treatment. RAW 264.7 cell proliferation reached peak value at 50 ug/mL of VA treatment exhibiting 108% of the basal value. Nitric oxide production by RAW 264.7 macrophage cells was slightly reduced by VA treatment but was not statistically significant. Moreover, the phagocytic activity of macrophages was enhanced by VA treatment. These results indicate that VA is effective in immune system.

Keywords: deer antler, splenocyte, bone marrow cells, macrophage proliferation, phagocytosis

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Authors: Juan Carlos Baena, Zhongxiao Peng

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Ultra-high molecular weight polyethylene (UHMWPE) is extensively used in industrial and biomedical fields. The slippery nature of UHMWPE makes this material suitable for surface bearing applications, however, the operational conditions limit the lubrication efficiency, inducing boundary and mixed lubrication in the tribological system. The lack of lubrication in a tribological system intensifies friction, contact stress and consequently, operating temperature. With temperature increase, the material’s mechanical properties are affected, and the lifespan of the component is reduced. The understanding of how mechanical properties and wear performance of UHMWPE change when the temperature is increased has not been clearly identified. The understanding of the wear and mechanical performance of UHMWPE at different temperature is important to predict and further improve the lifespan of these components. This study evaluates the effects of temperature variation in a range of 20 °C to 60 °C on the hardness and the wear resistance of UHMWPE. A reduction of the hardness and wear resistance was observed with the increase in temperature. The variation of the wear rate increased 94.8% when the temperature changed from 20 °C to 50 °C. Although hardness is regarded to be an indicator of the material wear resistance, this study found that wear resistance decreased more rapidly than hardness with the temperature increase, evidencing a low material stability of this component in a short temperature interval. The reduction of the hardness was reflected by the plastic deformation and abrasion intensity, resulting in a significant wear rate increase.

Keywords: hardness, surface bearing, tribological system, UHMWPE, wear

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Authors: Hyunki Kang, Hi Won Jeong

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The gas turbine operates for a long period of time under harsh, cyclic conditions of high temperature and pressure, where high turbine inlet temperature (TIT) can range from 1273 to 1873K. Therefore, Ni-base superalloys such as IN738, IN939, Rene 45, Rene 71, Rene 80, Mar M 247, CM 247, and CMSX-4 with excellent mechanical properties and resistance to creep, corrosion and oxidation at high temperatures are indeed used. Among the alloying additions for these alloys, aluminum (Al) and titanium (Ti) form gamma prime and enhance the high-temperature properties. However, when crack-damaged high-temperature turbine components such as blade and vane are repaired by fusion welding, they cause cracks. For example, when arc welding is applied to certain superalloys that contain Al and Ti with more than 3 wt.% and T3.5 wt%, respectively, such as IN738, IN939, Rene 80, Mar M 247, and CM 247, aging cracks occur. Therefore, repair technologies using diffusion brazing, which has less heat input into the base material, are being developed. Analysis of microstructural evolution of the brazed joints with a base metal of IN 939 Ni-base superalloy using brazing different filler metals was also carried out using X-ray diffraction, OEM, SEM-EDS, and EPMA. Stress rupture and high-temperature tensile strength properties were also measured to analyze the effects of different brazing heat cycles. The boron amount in the diffusion-affected zone (DAZ) was decreased towards the base metal and the formation of borides at grain boundaries was detected through EPMA.

Keywords: gas turbine, diffusion brazing, superalloy, gas turbine repair

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Authors: Hameed Alshammari

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The decarbonisation of the energy sector beyond the 21ˢᵗ century is akin to establishing morally responsible mechanisms that can propagate sustainable livelihoods (Denina et al., 2021). It implies that Kuwait undertakes a re-evaluation of energy generation gaps so as to tap the potential to reduce overreliance on fossil fuel (Si et al., 2020) and align with global views on sustainable energy generation and consumption.(Herrero, Pineda, Villar, & Zambrano, 2020). Without the economic pressure to switch to alternative sources of energy, Kuwait requires a multi-dimensional analysis the energy policies andsources of energy other than fossil fuels (Alsaad, 2021).Currently, Kuwait has an energy system that is highly skewed towards fossil fuels (Alsaad, 2021); hence, the reliance on burning fossil fuels forms part of the core elements of the general inefficient energy systems that have negative consequences to global environmental and economic systems (Kang et al., 2020). This paper undertakes a detailed literature review on factors needed for the development of a framework for the multi-dimensional energy resource analysis in Kuwait. The framework aims aligning the current energy policies in Kuwait with the global decarbonisation drive, to promote sustainable energy strategies.

Keywords: decarbonisation, energy, fossil fuels, multi-dimensional analysis, sustainability

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Authors: Bingjie Wang, Su-Yeon Kwon, Ik-Joong Kang

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The goal of this experiment is to develop a sensor that can quickly check the concentration by using the nanoparticles made by chitosan and gold. Using chitosan nanoparticles crosslinking with sodium tripolyphosphate(TPP) is the first step to form the chitosan nanoparticles, which would be covered with the gold sequentially. The size of the fabricated product was around 100nm. Based on the method that the sulfur end of the MPA linked to gold can form the very strong S–Au bond, and the carboxyl group, the other end of the MPA, can easily absorb the GABA. As for the GABA, what is the primary inhibitory neurotransmitter in the mammalian central nervous system in the human body. It plays such significant role in reducing neuronal excitability pass through the nervous system. A Surface-enhanced Raman Scattering (SERS) as the principle for enhancing Raman scattering by molecules adsorbed on rough metal surfaces or by nanostructures is used to detect the concentration change of γ-Aminobutyric Acid (GABA). When the system is formed, it generated SERS, which made a clear difference in the intensity of Raman scattering within the range of GABA concentration. So it is obtained from the experiment that the calibration curve according to the GABA concentration relevant with the SERS scattering. In this study, DLS, SEM, FT-IR, UV, SERS were used to analyze the products to obtain the conclusion.

Keywords: mercaptopropionic acid, chitosan-gold nanoshell, γ-aminobutyric acid, surface-enhanced raman scattering

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Authors: Ahmad Masduki Bin Selamat, Kang Chia Yang

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The International Standard Organization (ISO) is an international consensus on good management practice. It is derived from the Greek word “isos” meaning equal. ISO is aimed to give organization guidelines on what bring quality management system that leads to continuous improvement. The need of quality product is essential these days, especially in the manufacturing and service sectors. The requirement to produce good product is demanded, hence the certification of ISO enables the company to gain the trust from the public. Due to this, organizations whether government or private sectors in Malaysia are going for the ISO certification. However recently there has been an introduction of Islamic standard known as Islamic Standard Institute 2020 (ISI 2020). The ISI standards emphasize more on values that should be in the employees’ mind. By possessing good values, employees will work only for the betterment of the company. Currently only the feelings of being paid for the job exist in the employees’ mind. The non-Malays like Chinese and others, which comprise 40% of the sample size, are not aware about the existence of any Islamic quality system. As for the Malay managers, they support the Islamic quality systems. For them such values are encouraged by religion. By imitating religion, Allah promises a better life in this world and hereafter. Even though ISI 2020 is still new but the majority of Malays would support the need of Islamic quality system. Our findings suggest that integration of these two-quality systems running parallel would bring a better result.

Keywords: International Standard Organization (ISO), Islamic standard, quality, ISI 2020

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Authors: Jinwon Kang, Seonghak Jo, Joohee Ahn, Junghye Choi, Sun-Young Lee

Abstract:

A morphological priming has proved its importance by showing that segmentation occurs in morphemes when visual words are recognized within a noticeably short time. Regarding Sino-Korean prefixes, this study conducted an experiment on visual masked priming tasks with 57 ms stimulus-onset asynchrony (SOA) to see how individual differences in the amount of morphological knowledge affect morphological priming. The relationship between the prime and target words were classified as morphological (e.g., 미개척 migaecheog [unexplored] – 미해결 mihaegyel [unresolved]), semantical (e.g., 친환경 chinhwangyeong [eco-friendly]) – 무공해 mugonghae [no-pollution]), and orthographical (e.g., 미용실 miyongsil [beauty shop] – 미확보 mihwagbo [uncertainty]) conditions. We then compared the priming by configuring irrelevant paired stimuli for each condition’s control group. As a result, in the behavioral data, we observed facilitatory priming from a group with high morphological knowledge only under the morphological condition. In contrast, a group with low morphological knowledge showed the priming only under the orthographic condition. In the event-related potential (ERP) data, the group with high morphological knowledge presented the N250 only under the morphological condition. The findings of this study imply that individual differences in morphological knowledge in Korean may have a significant influence on the segmental processing of Korean word recognition.

Keywords: ERP, individual differences, morphological priming, sino-Korean prefixes

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Authors: Jae Young Jang, Jong Hoon Ahn, Jae-Woong Lim, So Young Kang, Mi Kyeong Lee

Abstract:

Rhus verniciflua is commonly known as a lacquer tree in Korea. Stem barks of R. verniciflua have been used as an immunostimulator in traditional medicine. It contains phenolic compounds and is known for diverse biological activities such as antioxidant and antimicrobial activity. However, it also causes allergic dermatitis due to urushiols derivatives. For the development of active natural resources with less toxicity, the content of phenolic compounds and urushiols of different parts of R. verniciflua such as stem barks, lignum and leaves were quantitated by colorimetric assay and HPLC analysis. The urushiols content were the highest in stem barks, and followed by leaves. The lignum contained trace amount of urushiols. The phenolic contents, however, were the most abundant in lignum, and followed by leaves and stem barks. These results clear showed that the content of urushiols and phenolic differs depending on the parts of R. verniciflua. Antimicrobial activity of different parts of R. verniciflua against fish pathogenic bacteria was also investigated using Edwardsiella tarda. Lignum of R. verniciflua was the most effective in antimicrobial activity against E. tarda and phenolic constituents are suggested to be active constituents for activity. Taken together, phenolic compounds are responsible for antimicrobial activity of R. verniciflua. The lignum of R. verniciflua contains high content of phenolic compounds with less urushiols, which suggests efficient antimicrobial activity with less toxicity. Therefore, lignum of R. verniciflua are suggested as good sources for antimicrobial activity against fish bacterial diseases.

Keywords: different parts, phenolic compounds, Rhus verniciflua, urushiols

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Authors: Jiandong Ren, Lijun Zhao, Peng Chen

Abstract:

Nafamostat (NA), a synthetic broad-spectrum serine protease inhibitor, has been routinely employed for the treatment of acute pancreatitis (AP) and other inflammatory-associated diseases in some East Asia countries. Although the potent inhibitory activity against inflammation-related proteases such as thrombin, trypsin, kallikrein, plasmin, coagulation factors and complement factors is generally considered to be responsible for the anti-inflammatory effects of NA, precise target and molecular mechanism underlying the anti-inflammatory activity in the treatment of AP remain largely unknown yet. As an intracellular inflammatory signaling platform, the NOD-like receptor protein 3 (NLRP3) inflammasome is recently identified to be involved in the development of AP. In present study, we have revealed that NA alleviated pancreatic injury in a caerulein-induced AP model by inhibiting the NLRP3 inflammasome activation in pancreas. Mechanistically, NA interacted with HDAC6, a cytoplasmic deacetylase implicated in the NLRP3 inflammasome pathway, and efficiently abrogated the function of HDAC6. This property enabled NA to influence HDAC6 dependent NF-κB transcriptional activity and thus block NF-κB-driven transcriptional priming of NLRP3 inflammasome. Moreover, NA exerted the potential to interfere HDAC6-mediated intracellular transport of NLRP3, thereby leading to the failure of NLRP3 inflammasome activation. Our current work has provided valuable insight into the molecular mechanism underlying the immunomodulatory effect of NA in treatment of AP, highlighting its promising application in prevention of NLRP3 inflammasome-associated inflammatory pathological damage.

Keywords: acute pancreatitis, HDAC6, nafamostat, NLRP3 inflammasome

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Authors: Ji Hye Im, Nguyen T. T. Phuong, Keon Wook Kang

Abstract:

Estrogens are important for the development and growth of estrogen receptor (ER)-positive breast cancer, for which anti-estrogen therapy is one of the most effective treatments. However, its efficacy can be limited by either de novo or acquired resistance. Aromatase is a key enzyme for the biosynthesis of estrogens, and inhibition of this enzyme leads to profound hypoestrogenism. Here, we found that the basal expression and activity of aromatase were significantly increased in tamoxifen (TAM)-resistant human breast cancer (TAMR-MCF-7) cells compared to control MCF-7 cells. We further revealed that aromatase immunoreactivity in tumor tissues was increased in recurrence group after TAM therapy compared to non-recurrence group after TAM therapy. Phosphorylation of Akt, extracellular signal-regulated kinase (ERK), and p38 kinase were all increased in TAMR-MCF-7 cells. Inhibition of phosphoinositide 3-kinase (PI3K) suppressed the transactivation of the aromatase gene and its enzyme activity. Furthermore, we have also shown that PI3K/Akt-dependent cAMP-response element binding protein (CREB) activation was required for the enhanced expression of aromatase in TAMR-MCF-7 cells. Our findings suggest that aromatase expression is up-regulated in TAM-resistant breast cancer via PI3K/Akt-dependent CREB activation.

Keywords: TAMR-MCF-7, CREB, estrogen receptor, aromatase

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Authors: Hyun-Soo Seol, In-Gun Kim, Hyun Seok Hong, Dong-Woo Kang, Ju Lee

Abstract:

Rotor of Spoke-Type PMSM is divided into permanent magnet and rotor core. Moreover, rotor core is composed of pole-piece, Bridge and rib. Piece between the permanent magnet N and S poles is pole-piece. Bridge and rib hold pole-piece. In the case of pole-piece and bridge, it is essential structure of Spoke-Type PMSM. However, Rib can be selected by the designer depending on the operating conditions and constraints. If rib is present in the rotor, rib which acts in the leak path generates a leakage flux. Although the leakage flux reduces the torque in low speed, it expands speed range in high speed. So, there is a relationship of trade off. Viewed from the standpoint of permanent magnet demagnetization, since the magnetic flux by the stator winding leaks to the rib, it is an advantage. In addition, rib affects the safety factor of the rotor. For application required high speed operation, since the securing the safety factor of the rotor is important, rib structure is advantageous. On the other hand, in the case of the application that does not require high speed operation, it is desirable to increase the output power by designing without rib. In this paper, Effects on rib structure is analyzed in detail and this paper provides designer with information about rotor design of spoke-type PMSM according to rib structure.

Keywords: spoke-Type PMSM, rotor shape, rib, operation range

Procedia PDF Downloads 428