Search results for: Bong Chan Kim

Authors: Andrey A. Chernousov, Ben Y. B. Chan

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The thermal behavior of a large-scale, phase change material (PCM) enhanced building envelope system was studied in regard to the need for pre-fabricated construction in subtropical regions. The proposed large-scale envelope consists of a reinforced aluminum skin, insulation core, phase change material and reinforced gypsum board. The PCM impact on an energy efficiency of an enveloped room was resolved by validation of the Energy Plus numerical scheme and optimization of a smart material location in the core. The PCM location was optimized by a minimization method of a cooling energy demand. It has been shown that there is good agreement between the test and simulation results. The optimal location of the PCM layer in Hong Kong summer conditions has been then recomputed for core thicknesses of 40, 60 and 80 mm. A non-dimensional value of the optimal PCM location was obtained to be same for all the studied cases and the considered external and internal conditions.

Keywords: thermal performance, phase change material, energy efficiency, PCM optimization

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Authors: Hsiao-Lung Chan, Ching-Yi Wu, Yan-Zou Lin, Yo Chiao, Ya-Ju Chang

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Robot-assisted bilateral arm training has demonstrated useful to improve motor control in stroke patients and save human resources. In clinics, the efficiency of this treatment is mostly performed by comparing functional scales before and after rehabilitation. However, most of these assessments are based on behavior evaluation. The underlying improvement of muscle activation and coordination is unknown. Moreover, stroke patients are easier to have muscle fatigue under robot-assisted rehabilitation due to the weakness of muscles. This safety issue is still less studied. In this study, EMG analysis was applied during training. Our preliminary results showed the co-contraction index and co-contraction area index can delineate the improved muscle coordination of biceps brachii vs. flexor carpiradialis. Moreover, the smoothed, normalized cycle-by-cycle median frequency of left and right extensor carpiradialis decreased as the training progress, implying the occurrence of muscle fatigue.

Keywords: robot-assisted rehabilitation, strokes, muscle coordination, muscle fatigue

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Authors: Rita Hairani, Warinthorn Chavasiri

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Naphthoquinones are secondary metabolites widespread in nature and can be produced by plants, fungi and actinomycetes. The interest of naphthoquinones is not only limited as organic dyes, but also their wide variety of biological activities such as antitumor, antibacterial, and cytotoxic activities. Typical 1,2-naphthoquinones such as mansonones can be found in Mansonia gagei Drumm. (“chan-cha-mod”), Sterculaceae family. This plant has been used traditionally to treat some diseases such as antiemetic and antidepressant. In this study, some natural mansonones isolated from the CH2Cl2 extract of M. gagei heartwood have been assessed for their antibacterial activities using agar well diffusion method. According to the antibacterial activity results of four natural mansonones (mansonones C, E, G and H), mansonones E and G showed higher activities than the others against Staphylococcus aureus, Propionibacterium acnes and Salmonella typhi, respectively. Since mansonone G exhibited good antibacterial activity and was obtained in the highest yield, we decided to derivertize mansonone G into five ether analogues. Based on the antibacterial activities of these synthesized compounds, four ether analogues (compounds 1-4) revealed higher antibacterial activities than its natural mansonone G against S. aureus and S. typhi.

Keywords: Mansonia gagei Drumm., antibacterial activities, mansonone G, ether analogues

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Authors: Ke Fan, Edwin H. W. Chan

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Economic incentives of green building (GB) have been implemented to promote green building and address the market barriers. However, if developers could gain from the incentives, why not all the buildings are green? This paper aims to study this problem and provide a new perspective to look at the economic incentives. The theories of Transitional Gains Trap (TGP) and Transaction Cost Economics (TCE) are employed to explain the developers’ gains and losses from the economic incentives. This paper takes the GFA (gross floor area) concession incentive in Hong Kong, which is one of the most popular incentives, as the case to conduct in-depth case study and it did interview to validate the results. The results show that after implementing the GFA concession scheme, the benefit of the GFA concession is capitalized into land value. Therefore, developers have to bear the increased land cost, which supports the theory of the TGP. Even though, some developers are still not willing to participate in the incentive scheme because of high transaction costs (TCs).

Keywords: green building, economic incentives, transitional gains trap, transaction cost

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Authors: Bong Jae Lee, Jeong Il Lee, Hyo Su Kim

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Both developed and developing countries have adopted the decision to join the Paris agreement to reduce greenhouse gas (GHG) emissions at the Conference of the Parties (COP) 21 meeting in Paris. As a result, the developed and developing countries have to submit the Intended Nationally Determined Contributions (INDC) by 2020, and each country will be assessed for their performance in reducing GHG. After that, they shall propose a reduction target which is higher than the previous target every five years. Therefore, an accurate method for calculating greenhouse gas emissions is essential to be presented as a rational for implementing GHG reduction measures based on the reduction targets. Non-CO2 GHGs (CF4, NF3, N2O, SF6 and so on) are being widely used in fabrication process of semiconductor manufacturing, and etching/deposition process of display manufacturing process. The Global Warming Potential (GWP) value of Non-CO2 is much higher than CO2, which means it will have greater effect on a global warming than CO2. Therefore, GHG calculation methods of the electronics industry are provided by Intergovernmental Panel on climate change (IPCC) and U.S. Environmental Protection Agency (EPA), and it will be discussed at ISO/TC 146 meeting. As discussed earlier, being precise and accurate in calculating Non-CO2 GHG is becoming more important. Thus this study aims to discuss the implications of the calculating methods through comparing the methods of IPCC and EPA. As a conclusion, after analyzing the methods of IPCC & EPA, the method of EPA is more detailed and it also provides the calculation for N2O. In case of the default emission factor (by IPCC & EPA), IPCC provides more conservative results compared to that of EPA; The factor of IPCC was developed for calculating a national GHG emission, while the factor of EPA was specifically developed for the U.S. which means it must have been developed to address the environmental issue of the US. The semiconductor factory ‘A’ measured F gas according to the EPA Destruction and Removal Efficiency (DRE) protocol and estimated their own DRE, and it was observed that their emission factor shows higher DRE compared to default DRE factor of IPCC and EPA Therefore, each country can improve their GHG emission calculation by developing its own emission factor (if possible) at the time of reporting Nationally Determined Contributions (NDC). Acknowledgements: This work was supported by the Korea Evaluation Institute of Industrial Technology (No. 10053589).

Keywords: non-CO2 GHG, GHG emission, electronics industry, measuring method

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Authors: Gou-Moon Choi, Woo-Young Jung, Chan-Young Yune

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Recently, the natural disaster has increased worldwide. In Korea, the damage to life and property caused by a typhoon, heavy rain, heavy snow, and an extreme wind also increases every year. Among natural disasters, the frequency and the strength of wind have increased because sea surface temperature has risen due to the increase of the average temperature of the Earth. In the case of extreme wind disaster, it is impossible to control or reduce the occurrence, and the recovery cost always exceeds the damage cost. Therefore, quantitative estimation of the damage cost for extreme wind needs to be established beforehand to install proactive countermeasures. In this study, the damage cost for private properties was analyzed based on the data for the past 10 years in Korea. The damage cost curve was also suggested for the metropolitan cities and provinces. The result shows the possibility for the regional application of the damage cost curve because the damage cost of the regional area is estimated based on the cost of cities and provinces.

Keywords: damage cost, extreme wind, natural disaster, private property

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Authors: Edward C. W. Chan, Benny C. F. Cheung

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In the knowledge economy, the financial indicator is not the unique instrument to gauge the performance of a company. The role of intellectual capital contributing to the company performance is increasing. To measure the company performance due to intellectual capital, the value-added intellectual capital (VAIC) model is adopted to measure the intellectual capital utilisation efficiency of the subject companies. The purpose of this study is to review the readiness of measuring intellectual capital for the Hong Kong listed companies in the property development and property investment industry by using VAIC model. This study covers the financial reports from the representative Hong Kong listed property development companies and property investment companies in the period 2014-2019. The findings from this study indicated the industry is ready for IC measurement employing VAIC framework but not yet ready for using the extended VAIC model.

Keywords: intellectual capital, intellectual capital measurement, property development, property investment, Skandia navigator, VAIC

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Authors: John Chan, Jake Linnenbank, Gavin Caird

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Automatic Selective Door Operation (ASDO) systems are increasingly used in railways to provide Correct Side Door Enable (CSDE) protection as well as to protect passenger doors opening off the platform where the train is longer than the platform, or in overshoot or undershoot scenarios. Such ASDO systems typically utilise trackside-installed RFID beacons, such as Eurobalises for odometry positioning purposes. Installing such trackside infrastructure may not be desirable or possible due to various factors such as conflict with existing infrastructure, potential damage from track tamping and jurisdiction constraints. Ultra-wideband (UWB) positioning technology could enable ASDO positioning requirements to be met without requiring installation of equipment directly on track since UWB technology can be installed on adjacent infrastructure such as on platforms. This paper will explore the feasibility of upgrading existing ASDO systems with UWB positioning technology, the feasibility of retrofitting UWB-enabled ASDO systems onto unfitted trains, and any other considerations relating to the use of UWB positioning for ASDO applications.

Keywords: UWB, ASDO, automatic selective door operations, CSDE, correct side door enable

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Authors: Joon-Hyung Kim, Him-Chan Lee, Jin-Hyuk Kim, Yong-Kab Lee, Young-Seok Choi

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The crude oil in an oil well exists in various phases such as gas, seawater, and sand, as well as oil. Therefore, a phase separator is needed at the front of a single-phase pump for pressurization and transfer. On the other hand, the application of a multiphase pump can provide such advantages as simplification of the equipment structure and cost savings, because there is no need for a phase separation process. Therefore, the crude oil transfer method using a multiphase pump is being applied to recently developed oil wells. Due to this increase in demand, technical demands for the development of multiphase pumps are sharply increasing, but the progress of research into related technologies is insufficient, due to the nature of multiphase pumps that require high levels of skills. This study was conducted to verify the reliability of pump performance evaluation using numerical analysis, which is the basis of the development of a multiphase pump. For this study, a model was designed by selecting the specifications of the pump under study. The performance of the designed model was evaluated through numerical analysis and experiment, and the results of the performance evaluation were compared to verify the reliability of the result using numerical analysis.

Keywords: multiphase pump, numerical analysis, experiment, performance evaluation, reliability verification

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Authors: Ki Hyun Park, Hye Min Park, Jeong Ho Kim, Chan Jong Park, Koan Sik Joo

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In the modern days, the use of radioactive substances is on the rise in the areas like chemical weaponry, industrial usage, and power plants. Although there are various technologies available to detect and monitor radioactive substances in the air, the technologies to detect underwater radioactive substances are scarce. In this study, computer simulation of the underwater detection system measuring beta-ray, a radioactive substance, has been done through MCNP. CaF₂, YAP(Ce) and YAG(Ce) have been used in the computer simulation to detect beta-ray as scintillator. Also, the source used in the computer simulation is Sr-90 and Y-90, both of them emitting only pure beta-ray. The distance between the source and the detector was shifted from 1mm to 10mm by 1 mm in the computer simulation. The result indicated that Sr-90 was impossible to measure below 1 mm since its emission energy is low while Y-90 was able to be measured up to 10mm underwater. In addition, the detector designed with CaF₂ had the highest efficiency among 3 scintillators used in the computer simulation. Since it was possible to verify the detectable range and the detection efficiency according to modeling through MCNP simulation, it is expected that such result will reduce the time and cost in building the actual beta-ray detector and evaluating its performances, thereby contributing the research and development.

Keywords: Beta-ray, CaF₂, detector, MCNP simulation, scintillator

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Authors: So-Ra Jeon, Chan Byon

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This study investigates the heat transfer characteristics of aluminum foam heat sink and pin fin heat sink subjected to an impinging air jet under a fixed pumping power condition as well as fixed flow rate condition. The effects of dimensionless pumping power or the Reynolds number and the impinging distance ratio on the Nusselt number are considered. The result shows that the effect of the impinging distance on the Nusselt number is negligible under a fixed pumping power condition, while the Nusselt number increases with decreasing the impinging distance under a fixed pumping power condition. A correlation for the pressure drop is obtained as a function of the flow rate and the impinging distance ratio. And correlations for the stagnation Nusselt number of the impinging jet are developed as a function of the pumping power. The aluminum foam heat sinks did not show higher thermal performance compared to a conventional pin fin heat sink under a fixed pumping power condition.

Keywords: aluminum foam, heat sinks, impinging jet, pumping power

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Authors: Wing Cheuk Chan

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It is well-known that Heidegger was highly critical of Sartre’s existential philosophy. In his famous “Letter on Humanism,” Heidegger not only draw a clear cutline between his thinking of Being and Sartre’s existentialism but also introduced a kind of anti-humanism. Such a hostile attitude towards Sartre’sExistentialism as Humanism seems to have created an unbridgeable gap between these them. Indeed, already in his Being and Nothingness, Sartre complained: Heidegger “has completely avoided any appeal to consciousness in his description of Dasein.”In reality, Sartre was mainly faithful to Husserlianphenomenology, in spite of his rejection of Husserl’s idealism. Thanks to the Japanese Buddhist scholar Yoshifumi Ueda’s work on the Old School of Yogācāra Buddhismas represented by Sthiramati and Paramārtha, we learn that in additional to thethesis of transforming vijñāna (knowing consciousness) into jñāna (wisdom), there is an idea of pṛṣṭa-labdha-jñāna (the subsequently acquired wisdom). According to Ueda, the latter is a “non-discriminative discrimination.” This gives rise to a possibility of synthesizing Heidegger’s thinking of Being and Sartre’s existential phenomenology. Structurally, this paper will firstshow that Heidegger focuses on the side of non-discrimination, whereas Sartre concentrates on the side of discrimination. It will then clarify in what sense thateach of them, in itself, remains incomplete. Finally, it will demonstratehow to synthesize them in term of the notion of “non-discriminative discrimination.”

Keywords: heidegger, sartre, phenomenology, yogācāra buddhism

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Authors: Aklilu Alemu, Tak Cheung Chan

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Following the intensification of secondary education in the developing world, the attention of Ethiopia has currently shifted to its quality education and its management. This study is aimed to explore experts’ perceptions of quality management challenges in secondary education in Ethiopia. The researchers employed a case study design recruiting participating supervisors from the Ministry of Education, region, zone, wereda, and cluster by using a purposeful sampling technique. Twenty-six interviewees took part in this study. The researchers employed NVivo 8 versions together with a thematic analysis process to analyze the data. This study revealed that major problems that affected quality management practices in Ethiopia were: lack of qualified experts at all levels; lack of accountability in every echelon; the changing nature of teacher education; the ineffectiveness of teacher-licensing programs; and lack of educational budget and the problem of utilizing this limited budget. The study concluded that the experts at different levels were not genuinely fulfilling their roles and responsibilities. Therefore, the Ministry of Finance and Economic Development, together with the concerned parties, needs to reconsider budget allocation for secondary education.

Keywords: education quality, Ethiopia, quality challenge, quality management, secondary education

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Authors: Seyedeh Mozhgan Seyed-Talebi, Weng-Kent Chan, Hsin-Yi Tiffany Chen

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Lead-free perovskite photovoltaic (PV) technology employing non-toxic tin halide perovskite absorbers is pivotal for advancing perovskite solar cell (PSC) commercialization. Despite challenges posed by perovskite sensitivity to oxygen and humidity, our study utilizes DFT calculations using VASP and NanoDCAL software and SCAPS-1D simulations to elucidate the charge transport mechanism at the interface of CsSnI₃-FASnI₃ heterojunction. Results reveal how inherent electric fields facilitate efficient carrier transport, reducing recombination losses. We predict optimized power conversion efficiencies (PCEs) and highlight the potential of CsSnI3-FASnI3 heterojunctions for cost-effective and efficient charge transport layer-free (CTLF) photovoltaic devices. Our study provides insights into the future direction of recognizing more efficient, nontoxic heterojunction perovskite devices.

Keywords: charge transport layer free, CsSnI₃-FASnI₃ heterojunction, lead-free perovskite solar cell, tin halide perovskite., Charge transport layer free

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Authors: Chan Ka Lok Sobel

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The rapid evolution of digital media platforms has given rise to new forms of narrative engagement, particularly through multi-channel storytelling. This research focuses on exploring the teaching pedagogy and effectiveness of multi-channel storytelling for social media, cinema, games, and streaming platforms. The study employs case studies of the popular series "Squid Game" to investigate the diverse pedagogical approaches and strategies used in teaching multi-channel storytelling. Through qualitative research methods, including interviews, surveys, and content analysis, the research assesses the effectiveness of these approaches in terms of student engagement, knowledge acquisition, critical thinking skills, and the development of digital literacy. The findings contribute to understanding best practices for incorporating multi-channel storytelling into educational contexts and enhancing learning outcomes in the digital media landscape.

Keywords: digital literacy, game-based learning, artificial intelligence, animation production, educational technology

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Authors: José Davi Oliveira De Moura, Chou Sin Chan

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In this study, the effect of convective momentum transport (CMT) on the life of cyclone systems and their organization is analyzed. A case of strong precipitation, in the southeast of Brazil, was simulated using Eta model with two kinds of convective parameterization: Kain-Fritsch without CMT and Kain-fritsch with CMT. Reanalysis data from CFSR were used to compare Eta model simulations. The Wind, mean sea level pressure, rain and temperature are included in analysis. The rain was evaluated by Equitable Threat Score (ETS) and Bias Index; the simulations were compared among themselves to detect the influence of CMT displacement on the systems. The result shows that CMT process decreases the intensity of meso cyclones (higher pressure values on nuclei) and change the positions and production of rain. The decrease of intensity in meso cyclones should be caused by the dissolution of momentum from lower levels from up levels. The rain production and rain distribution were altered because the displacement of the larger systems scales was changed. In addition, the inclusion of CMT process is very important to improve the simulation of life time of meteorological systems.

Keywords: convection, Kain-Fritsch, momentum, parameterization

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Authors: Dana Lee, Young Chan Kim

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The purpose of this paper is to examine the relationship between the fashion corporate social responsibility (CSR) ad framing and consumer purchase behaviours with the focus on consumer’s concern and involvement towards fashion brands. A self-completion questionnaire was administered to 200 respondents. Factor analysis and other statistical analyses were applied to test hypotheses. The results suggested that the quality of the product was the most important factor when consumers purchase fashion brand products with high level of responsibility towards unethical practices but surprisingly favourability for fast fashion. Unexpectedly, it was shown that consumers took the plenty of blame, but not much responsibility on buying fast fashion evading their responsibility to CSR ad, and their purchase intentions remained unchanged. The result, on the other hand, showed that fashion CSR ads can significantly moderate individuals’ emotions even though this had no significant correlation with the purchase intentions. Despite the limited sample size and geographical region, this research has important implications for contemporary fashion brands that use ad framing to understand how consumers’ involvement and concernedness toward the CSR actions in ad, influence their favourability (purchase intention) for fashion brands.

Keywords: framing effect, CSR advertisements, consumer behaviour, purchase intention

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Authors: Nadali Babaeian Jelodar, Chan Lai Keng, Arvind Bhatt, Laleh Bordbar, Leow E Shuen, Kamaruzaman Mohamed

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Recently artemisinin (the endoperoxide sesquiterpene lactone) has received considerable attention because of its antimalarial activity. It is isolated from the aerial part of the Artemisia annua L. Artemisinin is very difficult to synthesise also its production by mean of cell, tissue or organ cultures is very low. Presently, only its extraction from A. annua L. plants remains the only source of the drug. The reported yield of artemisinin from leaves of A. annua L. is very low and unstable, with yields typically less than 1% of leaf dry weight. To increase the percentage of artemisinin, researchers have been engaged in developing new varieties. A review concerning the breeding of A. annua L. is presented. The aim of this review is to bring together most of the available scientific research papers about the breeding conducted on the genus A. annua L., which is currently scattered across various publications. Through this review the authors hope to attract the attention of breeders throughout the world to focus on the unexplored potential of A. annua L. species. Also the future scope of this plant has been emphasized with a view of the importance of breeding of A. annua L. for increasing of artemisinin content. By releasing of new cultivar of A. annua L. and cultivation of this plant offers the opportunity to optimize yield and achieve a uniform, high quality product.

Keywords: Artemisia annua L., breeding, artemisinin, cultivation, medicinal plant

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Authors: Minsun Kim, Ki-Sun Choi, Hyun-Jee Lee, Young-Chan You

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There is no reinforcement example for the renovation of the vertical and horizontal extension to existing building structures which is a shear wall type in apartment units in Korea. Among these existing structures, the structures which are shear wall type are rare overseas, while Korea has many shear wall apartment units. Recently, in Korea, a few researchers are trying to confirm the possibility of the vertical extension in existing building with shear walls. This study evaluates the possibility of the renovation by applying performance-based seismic design to existing buildings with shear walls in the analysis phase of the structure. In addition, force-based seismic design, used by general structural engineers in Korea, is carried out to compare the amount of reinforcement of walls, which is a main component of wall structure. As a result, we suggest that performance-based design obtains more economical advantages than force-based seismic design.

Keywords: design for extension, performance-based design, remodeling, shear wall frame, structural analysis

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Authors: Chan Kwon Park, Chae-Bogk Kim, Sung-Min Park

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This study is a research on the authenticity of transactions between corporations and quality of their relationships and transaction performances. As the factors of authenticity of transactions, honesty, transparency, customer orientation and consistency were selected; as the factors of quality of relationships, trust and commitment were selected, and as the factors of transactions performances, intention of repeat transactions and switching intention were selected, and on these relationships a hypothesis was established, and verification was conducted. First, the factors of the authenticity of transactions positively influenced the factors of quality of relationships. Thus, a higher level of authenticity of transactions can lead to higher level of trust and commitment. Second, the factors of quality of relationships made a positive influence on the intention of repeat transactions, while a negative influence in the switching intention. Third, it showed that trust and commitment as the factors of quality of relationships functioned partly as the parameter between the authenticity of transactions and transaction performances. Finally, it proved that the factors of the authenticity of transactions improved trust and commitment in transactions between corporations and further improved the intention of repeat transactions while they decreased the switching intention.

Keywords: authenticity of transactions, trust, commitment, intention of repeat transactions, switching intention

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Authors: Md. Maksudur Rahman Khan, Chee Wai Woon, Huei Ruey Ong, Vignes Rasiah, Chin Kui Cheng, Kar Min Chan, E. Baranitharan

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The present work represents a preparation of non-precious iron-based electrocatalyst (FeN) for ORR in air-cathode microbial fuel cell by pyrolysis treatment. Iron oxalate which recovered from the industrial wastewater and Phenanthroline (Phen) were used as the iron and nitrogen precursors, respectively in preparing FeN catalyst. The performance of as prepared catalyst (FeN) was investigated in a single chambered air cathode MFC in which anaerobic sludge was used as inoculum and palm oil mill effluent as substrate. The maximum open circuit potential (OCV) and the highest power density recorded were 0.543 V and 4.9 mW/m2, respectively. Physical characterization of FeN was elucidated by using Brunauner Emmett Teller (BET), X-Ray Diffraction (XRD) analysis and Field Emission Scanning Electron Microscopy (FESEM) while the electrochemical properties were characterized by cyclic voltammetry (CV) analysis. The presence of biofilm on anode surface was examined using FESEM and confirmed using Infrared Spectroscopy and Thermogravimetric Analysis. The findings of this study demonstrated that FeN is electrochemically active and further modification is needed to increase the ORR catalytic activity.

Keywords: iron based catalyst, microbial fuel cells, oxygen reduction reaction, palm oil mill effluent

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Authors: Paola Pannuzzo, Tak-Ming Chan

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In seismic applications, hollow steel sections show, beyond undeniable esthetical appeal, promising structural advantages since, unlike open section counterparts, they are not susceptible to weak-axis and lateral-torsional buckling. In particular, hot-finished hollow steel sections have homogeneous material properties and favorable ductility but have been underutilized for cyclic bending. The main reason is that the parameters affecting their hysteretic behaviors are not yet well understood and, consequently, are not well exploited in existing codes of practice. Therefore, experimental investigations have been conducted on a wide range of hot-finished rectangular hollow section beams with the aim to providing basic knowledge for evaluating their seismic performance. The section geometry (width-to-thickness and depth-to-thickness ratios) and the type of loading (monotonic and cyclic) have been chosen as the key parameters to investigate the cyclic effect on the rotational capacity and to highlight the differences between monotonic and cyclic load conditions. The test results provide information on the parameters that affect the cyclic performance of hot-finished hollow steel beams and can be used to assess the design provisions stipulated in the current seismic codes of practice.

Keywords: bending, cyclic test, finite element modeling, hollow sections, hot-finished sections

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Authors: Andrey A. Chernousov, Ben Y. B. Chan

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The use of the low-cost paraffinic phase change material can be rather effective in smart building envelopes in the South China region. Particular attention has to be paid to the PCM optimization as an exploitation conditions and the envelope insulation changes its thermal characteristics. The studied smart building envelope consists of a reinforced aluminum exterior, polymeric insulation foam, phase change material and reinforced interior gypsum board. A prototype sample was tested to validate the numerical scheme using EnergryPlus software. Three scenarios of insulation thermal resistance loss (ΔR/R = 0%, 25%, 50%) were compared with the different PCM thicknesses (tP=0, 1, 2.5, 5 mm). The comparisons were carried out for a west facing enveloped office building (50 storey). PCM optimization was applied to find the maximum efficiency for the different ΔR/R cases. It was found, during the optimization, that the PCM is an important smart component, lowering the peak energy demand up to 2.7 times. The results are not influenced by the insulation aging in terms of ΔR/R during long-term exploitation. In hot and humid climates like Hong Kong, the insulation core of the smart systems is recommended to be laminated completely. This can be very helpful in achieving an acceptable payback period.

Keywords: smart building envelope, thermal performance, phase change material, energy efficiency, large-scale sandwich panel

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Authors: Niya Chen, Jennifer Chan

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In the financial market, risk management helps to minimize potential loss and maximize profit. There are two ways to assess risks; the first way is to calculate the risk directly based on the volatility. The most common risk measurements are Value at Risk (VaR), sharp ratio, and beta. Alternatively, we could look at the quantile of the return to assess the risk. Popular return models such as GARCH and stochastic volatility (SV) focus on modeling the mean of the return distribution via capturing the volatility dynamics; however, the quantile/expectile method will give us an idea of the distribution with the extreme return value. It will allow us to forecast VaR using return which is direct information. The advantage of using these non-parametric methods is that it is not bounded by the distribution assumptions from the parametric method. But the difference between them is that expectile uses a second-order loss function while quantile regression uses a first-order loss function. We consider several quantile functions, different volatility measures, and estimates from some volatility models. To estimate the expectile of the model, we use Realized Conditional Autoregressive Expectile (CARE) model with the bayesian method to achieve this. We would like to see if our proposed models outperform existing models in cryptocurrency, and we will test it by using Bitcoin mainly as well as Ethereum.

Keywords: expectile, CARE Model, CARR Model, quantile, cryptocurrency, Value at Risk

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Authors: Ying Qi Chan, Chunyu Li, Xu Rou Yoyo Ma, Yaya Li, Saber Khederzadeh

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In the ever-evolving landscape of genome extraction protocols, the existing methodologies grapple with issues ranging from sub-optimal yields and compromised quality to time-intensive procedures and reliance on hazardous reagents, often necessitating substantial tissue quantities. This predicament is particularly challenging for scientists in developing countries, where resources are limited. Our investigation presents a protocol for the efficient extraction of high-yield RNA from various tissues such as muscle, insect, and plant samples. Noteworthy for its advantages, our protocol stands out as the safest, swiftest (completed in just 38 minutes), most cost-effective (coming in at a mere US$0.017), and highly efficient method in comparison to existing protocols. Notably, our method avoids the use of hazardous or toxic chemicals such as chloroform and phenol and enzymatic agents like RNase and Proteinase K. Our RNA extraction protocol has demonstrated clear advantages over other methods, including commercial kits, in terms of yield. This nucleic acid extraction protocol is more environmentally and research-friendly, suitable for a range of tissues, even in tiny volumes, hence facilitating various genetic diagnosis and researches across the globe.

Keywords: RNA extraction, rapid protocol, universal method, diverse tissues

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Authors: Chih-Wei Cheng, Wei-Jen Chan, Yu-Han Huang, Yi-Tsung Lin, Yen-Wei Huang, Min-Cheng Chen, Shou-Zen Chang, G. Chern, Yuan-Chieh Tseng

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How to develop spin-orbit-torque (SOT) devices with the virtues of field-free, perpendicular magnetic anisotropy (PMA), and low switching current is one of the many challenges in spintronics today. We propose a CoFeB/Ta/CoFeB tri-layer antiferromagnetic SOT device that could meet the above requirements. The device’s PMA was developed by adopting CoFeB–MgO interface. The key to the success of this structure is to ensure that (i)changes of the inter-layer coupling(IEC) and CoFeB anisotropy can occur simultaneously; (ii) one of the CoFeB needs to have a slightly tilted moment in the beginning. When sufficient current is given, the SHEreverses the already-tiltedCoFeB, and the other CoFeB can be reversed simultaneously by the IEC with the field-free nature. Adjusting the thickness of Ta can modify the coupling state to reduce the switching current while the field-free nature was preserved. Micromagnetic simulation suggests that the Néel orange peel effect (NOPE) is non-negligible due to interface roughness and coupling effect in the presence of perpendicular anisotropy. Fortunately, the Néel field induced by the NOPE appears to favor the field-free reversal.

Keywords: CoFeB, spin-orbit torque, antiferromagnetic, MRAM, trilayer

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Authors: Kuang-Hsiung Tan, Chih-Chan Hu, Chien-Wu Lan, Shih-Sung Lin, Te-Jen Chang

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An active islanding detection method using disturbance signal injection with intelligent controller is proposed in this study. First, a DC\AC power inverter is emulated in the distributed generator (DG) system to implement the tracking control of active power, reactive power outputs and the islanding detection. The proposed active islanding detection method is based on injecting a disturbance signal into the power inverter system through the d-axis current which leads to a frequency deviation at the terminal of the RLC load when the utility power is disconnected. Moreover, in order to improve the transient and steady-state responses of the active power and reactive power outputs of the power inverter, and to further improve the performance of the islanding detection method, two probabilistic fuzzy neural networks (PFNN) are adopted to replace the traditional proportional-integral (PI) controllers for the tracking control and the islanding detection. Furthermore, the network structure and the online learning algorithm of the PFNN are introduced in detail. Finally, the feasibility and effectiveness of the tracking control and the proposed active islanding detection method are verified with experimental results.

Keywords: distributed generators, probabilistic fuzzy neural network, islanding detection, non-detection zone

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Authors: S. S. Dol, M. S. Chan, S. F. Wong, J. S. Lim

Abstract:

Emulsion formation is unavoidable and can be detrimental to an oil field production. The presence of stable emulsions also reduces the quality of crude oil and causes more problems in the downstream refinery operations, such as corrosion and pipeline pressure drop. Hence, it is important to know the effects of emulsions in the pipeline. Light crude oil was used for the continuous phase in the W/O emulsions where the emulsions pass through a flow loop to test the pressure drop across the pipeline. The results obtained shows that pressure drop increases as water cut is increased until it peaks at the phase inversion of the W/O emulsion between 30% to 40% water cut. Emulsions produced by gradual constrictions show a lower stability as compared to sudden constrictions. Lower stability of emulsions in gradual constriction has the higher influence of pressure drop compared to a sudden sharp decrease in diameter in sudden constriction. Generally, sudden constriction experiences pressure drop of 0.013% to 0.067% higher than gradual constriction of the same ratio. Lower constriction ratio cases cause larger pressure drop ranging from 0.061% to 0.241%. Considering the higher profitability in lower emulsion stability and lower pressure drop at the developed flow region of different constrictions, an optimum design of constriction is found to be gradual constriction with a ratio of 0.5.

Keywords: constriction, pressure drop, turbulence, water-in-oil emulsions

Procedia PDF Downloads 334

Authors: Mei Xuan Tan, Eng Ying Bong

Abstract:

Academic discussion during and after instructional teaching is an integral part of learning. Such discussion between the instructor and student or peer-to-peer discussion can be in several different forms. It could be face-to-face discussion, via email and use of online discussion forum. In this study, the effectiveness of using WhatsApp for academic discussion for a first year half-credit Chemistry course was examined. This study was run over two years with two different batches of students. Participation in the study was voluntary and student volunteers were recruited within the first week of the term. The activity in the WhatsApp group was monitored by two instructors teaching the course. At the end of the course, the students participated in an online survey to evaluate their experience of using WhatsApp for academic discussion. There were a total of 26 questions. The survey had a total of 4 sections with regards to the use of WhatsApp for academic discussion: 1) Familiarity with WhatsApp, 2) Effectiveness of using WhatsApp for discussion, 3) Challenges and 4) Overall experience. The main purpose of using an IM platform for academic discussion was to encourage after-class discussion amongst the students. 32% of the participants had used other online platform, such as Piazza and forums in Learning Management System (LMS), for after-class academic discussion with their instructors and peers. This was a low percentage considering that some courses use such online platform as their main forum amongst instructors and students. At the end of our study, over 83% of the participants felt that WhatsApp was a more effective platform compared to other online forum. One interesting finding was the effect of WhatsApp discussion on face-to-face interaction with instructors. 28% of the students agreed that the use of WhatsApp as a discussion forum had encouraged them to approach their instructors during or after class. 51% of students answered neutral. This could be interpreted that the use of WhatsApp had not affected the frequent (or lack of) face-to-face interaction with their instructors. A second survey question, similar but phrased differently from the first, was also asked to evaluate the aspect of face-to-face interaction with instructors. 34% disagreed that the use of WhatsApp had reduced the frequency of face-to-face interaction. This could imply that the frequency remained the same or might have increased. The 38% who agreed to a decrease in face-to-face interaction have either asked the questions in WhatsApp or had their questions answered by a query from another student in the group chat. These outcomes suggested that the use of technology aided and complemented face-to-face interaction between instructors and students. The study also looked at the challenges of using WhatsApp for academic discussion. Some challenges included difficulty in referring back to previous discussion and students finding some discussions irrelevant to them. In conclusion, the use of IM platform for academic discussion was desirable for the students, but it should not be the only channel as face-to-face consultation and online forum for lengthy discussion are still important for after-class learning of students.

Keywords: chemistry, pedogogy, technological tools, undergraduate

Procedia PDF Downloads 135

Authors: Kevin Chan, Kevin K. H. Chung, Patcy P. S. Yeung, H. L. Ip, Bill T. C. Chung, Karen M. K. Chung

Abstract:

Purpose: Recent evidence shows that reading self-efficacy and students perceived difficulty in reading are significantly associated with word reading and reading fluency. However, little is known about these relationships among students learning to read English as a second language, particularly in Chinese students. This study examined the contributions of reading self-efficacy, perception of difficulty in reading, and cognitive-linguistic skills to performance on English word reading and reading fluency in Chinese students. Method: A sample of 122 second-and third-grade students in Hong Kong, China, participated in this study. Students completed the measures of reading self-efficacy and perception of difficulty in reading. They were assessed on their English cognitive-linguistic and reading skills: rapid automatized naming, nonword reading, phonological awareness, word reading, and one-minute word reading. Results: Results of path analysis indicated that when students’ grades were controlled, reading self-efficacy was a significant correlate of word reading and reading fluency, whereas perception of difficulty in reading negatively predicted word reading. Conclusion: These findings underscore the importance of taking students’ reading self-efficacy and perception of difficulty in reading and their cognitive-linguistic skills into consideration when designing reading intervention and instructions for students learning English as a second language.

Keywords: self-efficacy, perception of difficulty in reading, english as a second language, word reading

Procedia PDF Downloads 188