Search results for: Young Hoon Lee

Authors: Kyoung Hoon Kim

Abstract:

This paper presents a comparative exergy analysis of ammonia-water Rankine cycles with and without regeneration and Kalina cycle for recovery of low-temperature heat source. Special attention is paid to the effect of system parameters such as ammonia mass fraction and turbine inlet pressure on the exergetical performance of the systems. Results show that maximum exergy efficiency can be obtained in the regenerative Rankine cycle for high turbine inlet pressures. However, Kalina cycle shows better exergy efficiency for low turbine inlet pressures, and the optimum ammonia mass fractions of Kalina cycle are lower than Rankine cycles.

Keywords: Ammonia-water, Rankine cycle, Kalina cycle, exergy, exergy destruction, low-temperature heat source.

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Authors: Min Goo Choi, Jung Hoon Jung, Jae Wook Jeon

Abstract:

Assessment for image quality traditionally needs its original image as a reference. The conventional method for assessment like Mean Square Error (MSE) or Peak Signal to Noise Ratio (PSNR) is invalid when there is no reference. In this paper, we present a new No-Reference (NR) assessment of image quality using blur and noise. The recent camera applications provide high quality images by help of digital Image Signal Processor (ISP). Since the images taken by the high performance of digital camera have few blocking and ringing artifacts, we only focus on the blur and noise for predicting the objective image quality. The experimental results show that the proposed assessment method gives high correlation with subjective Difference Mean Opinion Score (DMOS). Furthermore, the proposed method provides very low computational load in spatial domain and similar extraction of characteristics to human perceptional assessment.

Keywords: No Reference, Image Quality Assessment, blur, noise.

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Authors: Sang Hoon Lee, Tae Il Lee, Su Jeong Lee, Jae Min Myoung

Abstract:

In order to manufacture short gap single Si nanowire (NW) field effect transistor (FET) by imprinting and transferring method, we introduce the method using Al2O3 sacrificial layer. The diameters of cylindrical Si NW addressed between Au electrodes by dielectrophoretic (DEP) alignment method are controlled to 106, 128, and 148 nm. After imprinting and transfer process, cylindrical Si NW is embedded in PVP adhesive and dielectric layer. By curing transferred cylindrical Si NW and Au electrodes on PVP-coated p++ Si substrate with 200nm-thick SiO2, 3μm gap Si NW FET fabrication was completed. As the diameter of embedded Si NW increases, the mobility of FET increases from 80.51 to 121.24 cm2/V·s and the threshold voltage moves from –7.17 to –2.44 V because the ratio of surface to volume gets reduced.

Keywords: Al2O3 Sacrificial transfer layer, cylindrical silicon nanowires, Dielectrophorestic alignment, Field effect transistor.

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Authors: Minh-Khai Nguyen, Young-Gook Jung, Young-Cheol Lim

Abstract:

It is known that if harmonic spectra are decreased, then acoustic noise also decreased. Hence, this paper deals with a new random switching strategy using DSP TMS320F2812 to decrease the harmonics spectra of single phase switched reluctance motor. The proposed method which combines random turn-on, turn-off angle technique and random pulse width modulation technique is shown. A harmonic spread factor (HSF) is used to evaluate the random modulation scheme. In order to confirm the effectiveness of the new method, the experimental results show that the harmonic intensity of output voltage for the proposed method is better than that for conventional methods.

Keywords: Single phase switched reluctance motor (SRM), harmonic spread factor (HSF), random switching technique.

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Authors: Kyoung Hoon Kim

Abstract:

Gas turbine systems with wet compression have a potential for future power generation, since they can offer a high efficiency and a high specific power with a relatively low cost. In this study influence of ambient condition on the performance of the wet compression process is investigated with a non-equilibrium analytical modeling based on droplet evaporation. Transient behaviors of droplet diameter and temperature of mixed air are investigated for various ambient temperatures. Special attention is paid for the effects of ambient temperature, pressure ratio, and water injection ratios on the important wet compression variables including compressor outlet temperature and compression work. Parametric studies show that downing of the ambient temperature leads to lower compressor outlet temperature and consequently lower consumption of compression work even in wet compression processes.

Keywords: water injection, droplet evaporation, wet compression, gas turbine, ambient condition

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Authors: Jae Keun Park, Sung Je Hong, Kyong Hoon Kim, Tae Heum Kang, Wan Yeon Lee

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In this paper, we propose a routing scheme that guarantees the residual lifetime of wireless sensor networks where each sensor node operates with a limited budget of battery energy. The scheme maximizes the communications QoS while sustaining the residual battery lifetime of the network for a specified duration. Communication paths of wireless nodes are translated into a directed acyclic graph(DAG) and the maximum-flow algorithm is applied to the graph. The found maximum flow are assigned to sender nodes, so as to maximize their communication QoS. Based on assigned flows, the scheme determines the routing path and the transmission rate of data packet so that any sensor node on the path would not exhaust its battery energy before a specified duration.

Keywords: Sensor network, battery, residual lifetime, routingscheme, QoS

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Authors: Pawit Monkolprasit, Proud Arunrangsiwed

Abstract:

It was important to understand the impact of media in young adolescents. The animated film, Khun Tong Dang the Inspirations (2015), was purposefully created for teaching young children to have a positive personal trait. The current study used this film as the case study. The objective is to understand the relationship between the good characteristic of movie audiences and their perception of the good characteristic of a movie character. One-hundred students from various age ranges responded to quantitative questionnaires. The questions included their age, gender, perception about their own personal traits, perception about their experiences with others, and perception about the bravery, intelligence, and gratefulness of the character. It was found that a good personal trait has a strong relationship with the perception of bravery, intelligence, and gratefulness of the character.

Keywords: Impact of media, children, personal trait, prosocial content.

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Authors: Hyung Jong Ko, Kyoung Hoon Kim

Abstract:

In this study thermodynamic performance analysis of a combined organic Rankine cycle and ejector refrigeration cycle is carried out for use of low-grade heat source in the form of sensible energy. Special attention is paid to the effects of system parameters including the turbine inlet temperature and turbine inlet pressure on the characteristics of the system such as ratios of mass flow rate, net work production, and refrigeration capacity as well as the coefficient of performance and exergy efficiency of the system. Results show that for a given source the coefficient of performance increases with increasing of the turbine inlet pressure. However, the exergy efficiency has an optimal condition with respect to the turbine inlet pressure.

Keywords: Coefficient of performance, ejector refrigeration cycle, exergy efficiency, low-grade energy, organic rankine cycle.

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Authors: Kyoung Hoon Kim

Abstract:

Turbine blade cooling is considered as the most effective way of maintaining high operating temperature making use of the available materials, and turbine systems with wet compression have a potential for future power generation because of high efficiency and high specific power with a relatively low cost. In this paper performance analysis of wet-compression gas turbine cycle with turbine blade cooling is carried out. The wet compression process is analytically modeled based on non-equilibrium droplet evaporation. Special attention is paid for the effects of pressure ratio and water injection ratio on the important system variables such as ratio of coolant fluid flow, fuel consumption, thermal efficiency and specific power. Parametric studies show that wet compression leads to insignificant improvement in thermal efficiency but significant enhancement of specific power in gas turbine systems with turbine blade cooling.

Keywords: Water injection, wet compression, gas turbine, turbine blade cooling.

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Authors: Hee-Jeong Ahn, Kee-Won Kim, Seung-Hoon Kim

Abstract:

The knowledge of the relationship between characters can help readers to understand the overall story or plot of the literary fiction. In this paper, we present a method for extracting the specific relationship between characters from a Korean literary fiction. Generally, methods for extracting relationships between characters in text are statistical or computational methods based on the sentence distance between characters without considering Korean linguistic features. Furthermore, it is difficult to extract the relationship with direction from text, such as one-sided love, because they consider only the weight of relationship, without considering the direction of the relationship. Therefore, in order to identify specific relationships between characters, we propose a statistical method considering linguistic features, such as syntactic patterns and speech verbs in Korean. The result of our method is represented by a weighted directed graph of the relationship between the characters. Furthermore, we expect that proposed method could be applied to the relationship analysis between characters of other content like movie or TV drama.

Keywords: Data mining, Korean linguistic feature, literary fiction, relationship extraction.

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Authors: Yoon Jung Sik, Bur-Deul Yoon, Ki Hun Kim, Chang Hoon

Abstract:

The purpose of this study was to examine the viewpoints in terms of changing distances and levels and thereby, comparatively analyze the visual sensitivity to the elements of the natural views. The questionnaire survey was conducted separately for experts and non-experts. Summing up, it was confirmed that the visual sensitivity to the elements of the same natural views differed significantly depending on subjects' professionalism, changes of the viewpoint levels and distances, while the visual sensitivity to 'openness of visual/view axes' did not differ significantly when only the distances of the viewpoints were varied. In addition, the visual sensitivity to visual/view axes differed between experts and ordinary people when the levels of the viewpoints were varied, while the visual sensitivity to 'damaged natural view resources' differed between two groups when the distances of the viewpoints were varied.

Keywords: Landscape Evaluation, Visual Sensitivity, Viewpoint.

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Authors: Kihyon Kwon, Hyun T. Park, Gil Y. Chung, Sang-Hoon Lee

Abstract:

This paper focuses on assessing sloshing-induced overflow of the seismically-isolated nuclear tanks based on Fluid-Structure Interaction (FSI) analysis. Typically, fluid motion in the seismically-isolated nuclear tank systems may be rather amplified and even overflowed under earthquake. Sloshing-induced overflow in those structures has to be reliably assessed and predicted since it can often cause critical damages to humans and environments. FSI analysis is herein performed to compute the total cumulative overflowed water volume more accurately, by coupling ANSYS with CFX for structural and fluid analyses, respectively. The approach is illustrated on a nuclear liquid storage tank, Spent Fuel Pool (SFP), forgiven conditions under consideration: different liquid levels, Peak Ground Accelerations (PGAs), and post earthquakes. 

Keywords: FSI analysis, seismically-isolated nuclear tank system, sloshing-induced overflow.

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Authors: Young-Jin Baik, Minsung Kim, Young-Soo Lee, Ki-Chang Chang, Seong-Ryong Park

Abstract:

The compression-absorption heat pump (C-A HP), one of the promising heat recovery equipments that make process hot water using low temperature heat of wastewater, was evaluated by computer simulation. A simulation program was developed based on the continuity and the first and second laws of thermodynamics. Both the absorber and desorber were modeled using UA-LMTD method. In order to prevent an unfeasible temperature profile and to reduce calculation errors from the curved temperature profile of a mixture, heat loads were divided into lots of segments. A single-stage compressor was considered. A compressor cooling load was also taken into account. An isentropic efficiency was computed from the map data. Simulation conditions were given based on the system consisting of ordinarily designed components. The simulation results show that most of the total entropy generation occurs during the compression and cooling process, thus suggesting the possibility that system performance can be enhanced if a rectifier is introduced.

Keywords: Waste heat recovery, Heat Pump.

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Authors: R. Ziaie Moayed , S. Tamassoki , E. Izadi

Abstract:

Investigation of sandy clay behavior is important since urban development demands mean that sandy clay areas are increasingly encountered, especially for transportation infrastructures. This paper presents the results of the finite element analysis of the direct shear test (under three vertical loading 44, 96 and 192 kPa) and discusses the effects of different parameters such as cohesion, friction angle and Young's modulus on the shear strength of sandy clay. The numerical model was calibrated against the experimental results of large-scale direct shear tests. The results have shown that the shear strength was increased with increase in friction angle and cohesion. However, the shear strength was not influenced by raising the friction angle at normal stress of 44 kPa. Also, the effect of different young's modulus factors on stress-strain curve was investigated.

Keywords: Shear strength, Finite element analysis, Large direct shear test, Sandy clay.

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Authors: Won Kyung Ham, Kang Hoon Cho, Yongho Chung, Sang C. Park

Abstract:

Presented in this paper is a framework of a software ‘WEMax’. The WEMax is invented for analysis and simulation for manned assembly lines to sustain and improve performance of manufacturing systems. In a manufacturing system, performance, such as productivity, is a key of competitiveness for output products. However, the manned assembly lines are difficult to forecast performance, because human labors are not expectable factors by computer simulation models or mathematical models. Existing approaches to performance forecasting of the manned assembly lines are limited to matters of the human itself, such as ergonomic and workload design, and non-human-factor-relevant simulation. Consequently, an approach for the forecasting and improvement of manned assembly line performance is needed to research. As a solution of the current problem, this study proposes a framework that is for generation and simulation of virtual manned assembly lines, and the framework has been implemented as a software.

Keywords: Performance Forecasting, Simulation, Virtual Manned Assembly Line.

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Authors: Hasan Atak, Figen Çok

Abstract:

Emerging Adulthood, the period during ages 18 to 25, is a new conceptualitation proposed by Arnett which is especially prevalent in the industrialized countries. Turkey is basically a developing country having a young population structure. Investigating the presence of such a life period in such a culture might be helpful in understanding educational and psychological needs of people who are in their twenties. With the aim of investigating Emerging Adulthood in Turkey, a well-known instrument (IDEA, 2003) was adapted to Turkish language and Turkish culture. The scale was administered to 296 participants between 15 and 34 ages and validity and reliability were conducted. Exploratory factor analysis revealed three subscales. Reliability coefficients of the scale (Cronbach a) was found as .69. Test-retest reliability coefficients was found for the scale as .81. Finally, “The IDEA" with 20 items was obtained to be used in the Turkish population. The instrument is ready to be administered among Turkish young people for the investigation of transition to adulthood, and whether such a emerging adulthood period really existed.

Keywords: Adaptation, Emerging Adulthood, Turkey, IDEA.

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Authors: C. Sridawruang

Abstract:

Young people today has sexual activities differing from those of earlier generations, in that teenagers are likely to have multiple partners, and are frequently in short-term relationships or with partners that are not well known to them. The proportion of teenage mothers in Thailand has increased. Young people were not specifically addressed during the overall very successful HIV-prevention campaigns. Because of this missed opportunity, they are still unaware of the risk of unsafe sexual behavior. Aims: To describe the reproductive health care services in perspectives of rural Thai teenagers Methods: This survey was one part of a mixed method approach taken using survey and focus groups with 439 teenagers aged 12-18 years in 5 villages, Udon Thani, Thailand. The standard questionnaire survey had been used for collecting data. The numeric data was checked and analyzed by using descriptive statistics. Results: Most teenager respondents stated that they do not know where sexual reproductive health services provided for them. Most teenagers felt difficult to access and talk with health staff about sexual related issues. They stated that discussing, or consulting with health providers might not be safe. Teenagers might lose opportunities to access and get advice from health care services. The mean knowledge score of contraception and condom reproductive was 6.34 from a total score 11. Most teenagers especially girls expressed a need for counseling services and reported a need for telephone services. Conclusions: The need of appropriate information focusing on sexual relationships and contraception should be designed to help young people make wise decisions and there should be set health care services for Thai teenagers to make sure that teenagers could access easily. Health care providers need to be trained to improve their knowledge, attitudes and skills in reproductive health care practices for Thai teenagers.

Keywords: Youth friendly health services, rural, Thai, teenagers.

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Authors: Qing Liu, Jean-Fabien Capsal, Claude Richard

Abstract:

In this current contribution, authors are dedicated to investigate influence of the crystal lamellae orientation on electromechanical behaviors of relaxor ferroelectric Poly (vinylidene fluoride –trifluoroethylene -chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) films by control of polymer microstructure, aiming to picture the full map of structure-property relationship. In order to define their crystal orientation films, terpolymer films were fabricated by solution-casting, stretching and hot-pressing process. Differential scanning calorimetry, impedance analyzer, and tensile strength techniques were employed to characterize crystallographic parameters, dielectric permittivity, and elastic Young’s modulus respectively. In addition, large electrical induced out-of-plane electrostrictive strain was obtained by cantilever beam mode. Consequently, as-casted pristine films exhibited surprisingly high electrostrictive strain 0.1774% due to considerably small value of elastic Young’s modulus although relatively low dielectric permittivity. Such reasons contributed to large mechanical elastic energy density. Instead, due to 2 folds increase of elastic Young’s modulus and less than 50% augmentation of dielectric constant, fullycrystallized film showed weak electrostrictive behavior and mechanical energy density as well. And subjected to mechanical stretching process, Film C exhibited stronger dielectric constant and out-performed electrostrictive strain over Film B because edge-on crystal lamellae orientation induced by uniaxially mechanical stretch. Hot-press films were compared in term of cooling rate. Rather large electrostrictive strain of 0.2788% for hot-pressed Film D in quenching process was observed although its dielectric permittivity equivalent to that of pristine as-casted Film A, showing highest mechanical elastic energy density value of 359.5 J/m3. In hot-press cooling process, dielectric permittivity of Film E saw values at 48.8 concomitant with ca.100% increase of Young’s modulus. Films with intermediate mechanical energy density were obtained.

Keywords: Crystal orientation, electrostrictive strain, mechanical energy density, permittivity, relaxor ferroelectric.

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Authors: Jeong-Min Jo, Young-Jae Han, Chang-Young Lee

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Attracting ferromagnetic forces between magnet and reaction rail provide the supporting force in Electromagnetic Suspension. Miniature maglev using permanent magnets and electromagnets is based on the idea to generate the nominal magnetic force by permanent magnets and superimpose the variable magnetic field required for stabilization by currents flowing through control windings in electromagnets. Permanent magnets with a high energy density have lower power losses with regard to supporting force and magnet weight. So the advantage of the maglev using electromagnets and permanent magnets is partially reduced by the power required to feed the remaining onboard supply system so that the overall onboard power is diminished as compared to that of the electromagnet. In this paper we proposed the how to design and control the miniature maglev and confirmed the feasibility of the levitation system using electromagnets and permanent magnets through the manufacturing the miniature maglev

Keywords: Magnetic Levitation system, Maglev, Permanent Magnets, Hybrid Magnet.

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Authors: Claudia Carbajal, Jija Dutt, Smriti Pahwa, Sumukhi Vaid, Karishma Vats

Abstract:

ASER Centre, the research and assessment arm of Pratham Education Foundation sees measurement as the first stage of action. ASER uses primary research to push and give empirical foundations to policy discussions at a multitude of levels. At a household level, common citizens use a simple assessment (a floor-level test) to measure learning across rural India. This paper presents the evidence on the applicability of an ASER approach to the health sector. A citizen-led assessment was designed and executed that collected information from young mothers with children up to a year of age. The pilot assessments were rolled-out in two different models: Paid surveyors and student volunteers. The survey covered three geographic areas: 1,239 children in the Jaipur District of Rajasthan, 2,086 in the Rae Bareli District of Uttar Pradesh, and 593 children in the Bhuj Block in Gujarat. The survey tool was designed to study knowledge of health-related issues, daily practices followed by young mothers and access to relevant services and programs. It provides insights on behaviors related to infant and young child feeding practices, child and maternal nutrition and supplementation, water and sanitation, and health services. Moreover, the survey studies the reasons behind behaviors giving policy-makers actionable pathways to improve implementation of social sector programs. Although data on health outcomes are available, this approach could provide a rapid annual assessment of health issues with indicators that are easy to understand and act upon so that measurements do not become an exclusive domain of experts. The results give many insights into early childhood health behaviors and challenges. Around 98% of children are breastfed, and approximately half are not exclusively breastfed (for the first 6 months). Government established diet diversity guidelines are met for less than 1 out of 10 children. Although most households are satisfied with the quality of drinking water, most tested households had contaminated water.

Keywords: Citizen-led assessment, infant and young children feeding, maternal nutrition, rapid health assessment supplementation, water and sanitation.

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Authors: Jong Hoon Kim, Hyun-Soo Lee, Moonseo Park, Min Jeong, Inbeom Lee

Abstract:

Pre-construction is essential in achieving the success of a construction project. Due to the early involvement of project participants in the construction phase, project managers are able to plan ahead and solve issues well in advance leading to the success of the project and the satisfaction of the client. This research utilizes quantitative data derived from construction management projects in order to identify the relationship between pre-construction, construction schedule, and client satisfaction. A total of 65 construction projects and 93 clients were investigated for this research in an attempt to identify (a) the relationship between pre-construction and schedule reduction, and (b) pre-construction and client loyalty. Based on the quantitative analysis, this research was able to establish a negative correlation based on 65 construction projects between pre-construction and project schedule existed. This finding represents that the more pre-construction is performed for a certain project, the overall construction schedule decreased. Then, to determine the relationship between pre-construction and client satisfaction, Net Promoter Score (NPS) of 93 clients from the 65 projects was utilized. Pre-construction and NPS was further analyzed and a positive correlation was found between the two. This infers that clients tend to be more satisfied with projects with higher ratio of pre-construction than those projects with less pre-construction.

Keywords: Client loyalty, NPS, pre-construction, schedule reduction.

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Authors: Jung-hoon Lee, Eung Tai Kim, Byung-hee Chang, In-hee Hwang, Dae-sung Lee

Abstract:

The accuracy of estimated stability and control derivatives of a light aircraft from flight test data were evaluated. The light aircraft, named ChangGong-91, is the first certified aircraft from the Korean government. The output error method, which is a maximum likelihood estimation technique and considers measurement noise only, was used to analyze the aircraft responses measures. The multi-step control inputs were applied in order to excite the short period mode for the longitudinal and Dutch-roll mode for the lateral-directional motion. The estimated stability/control derivatives of Chan Gong-91 were analyzed for the assessment of handling qualities comparing them with those of similar aircraft. The accuracy of the flight derivative estimates derived from flight test measurement was examined in engineering judgment, scatter and Cramer-Rao bound, which turned out to be satisfactory with minor defects..

Keywords: Light Aircraft, Flight Test, Accuracy, Engineering Judgment, Scatter, Cramer-Rao Bound

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Authors: Daehyoung Kim, Pervez Khan, Hoon Kim

Abstract:

Efficient utilization of spectrum resources is a fundamental issue of wireless communications due to its scarcity. To improve the efficiency of spectrum utilization, the spectrum sharing for unlicensed bands is being regarded as one of key technologies in the next generation wireless networks. A number of schemes such as Listen-Before-Talk(LBT) and carrier sensor adaptive transmission (CSAT) have been suggested from this aspect, but more efficient sharing schemes are required for improving spectrum utilization efficiency. This work considers an opportunistic transmission approach and a dynamic Contention Window (CW) adjustment scheme for LTE-U users sharing the unlicensed spectrum with Wi-Fi, in order to enhance the overall system throughput. The decision criteria for the dynamic adjustment of CW are based on the collision evaluation, derived from the collision probability of the system. The overall performance can be improved due to the adaptive adjustment of the CW. Simulation results show that our proposed scheme outperforms the Distributed Coordination Function (DCF) mechanism of IEEE 802.11 MAC.

Keywords: Spectrum sharing, adaptive opportunistic transmission, unlicensed bands, heterogeneous networks.

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Authors: Václav Maněna, Roman Dostál, Štěpán Hubálovský

Abstract:

Social networks play an important role in the lives of children and young people. Along with the high penetration of mobile technologies such as smartphones and tablets among the younger generation, there is an increasing use of social networks already in elementary school. The paper presents the results of research, which was realized at schools in the Hradec Králové region. In this research, the authors focused on issues related to communications on social networks for children, teenagers and young people in the Czech Republic. This research was conducted at selected elementary, secondary and high schools using anonymous questionnaires. The results are evaluated and compared with the results of the research, which has been realized in 2008. The authors focused on the possibilities of using social networks in education. The paper presents the possibility of using the most popular social networks in education, with emphasis on increasing motivation for learning. The paper presents comparative analysis of social networks, with regard to the possibility of using in education as well.

Keywords: Social networks, motivation, e-learning, mobile technology.

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Authors: Alexander A. Karabutov, Natalia B. Podymova, Elena B. Cherepetskaya, Vladimir A. Makarov, Yulia G. Sokolovskaya

Abstract:

The laser-ultrasonic method is realized for quantifying the influence of porosity on the local Young’s modulus of isotropic composite materials. The method is based on a laser thermooptical method of ultrasound generation combined with measurement of the phase velocity of longitudinal and shear acoustic waves in samples. The main advantage of this method compared with traditional ultrasonic research methods is the efficient generation of short and powerful probing acoustic pulses required for reliable testing of ultrasound absorbing and scattering heterogeneous materials. Using as an example samples of a metal matrix composite with reinforcing microparticles of silicon carbide in various concentrations, it is shown that to provide an effective increase in Young’s modulus with increasing concentration of microparticles, the porosity of the final sample should not exceed 2%.

Keywords: Laser ultrasonic, longitudinal and shear ultrasonic waves, porosity, composite, local elastic moduli.

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Authors: R. Bourziza, A. Hammani, M. Kuper, A. Bouaziz

Abstract:

In oases, the surface water resources are becoming increasingly scarce and groundwater resources, which generally have a poor quality due to the high levels of salinity, are often overexploited. Water saving have therefore become imperative for better oases sustainability. If drip irrigation is currently recommended in Morocco for saving water and valuing, its use in the sub-desert areas does not keep water safe from high evaporation rates. An alternative to this system would be the use of subsurface drip irrigation. This technique is defined as an application of water under the soil surface through drippers, which deliver water at rates generally similar to surface drip irrigation. As subsurface drip irrigation is a recently introduced in Morocco, a better understanding of the infiltration process around a buried source, in local conditions, and its impact on plant growth is necessarily required. This study aims to contribute to improving the water use efficiency by testing the performance of subsurface irrigation system, especially in areas where water is a limited source. The objectives of this research are performance evaluation in arid conditions of the subsurface drip irrigation system for young date palms compared to the surface drip. In this context, an experimental test is installed at a farmer’s field in the area of Erfoud (Errachidia Province, southeastern Morocco), using the subsurface drip irrigation system in comparison with the classic drip system for young date palms. Flow measurement to calculate the uniformity of the application of water was done through two methods: a flow measurement of drippers above the surface and another one underground. The latter method has also helped us to estimate losses through evaporation for both irrigation techniques. In order to compare the effect of two irrigation modes, plants were identified for each type of irrigation to monitor certain agronomic parameters (cumulative numbers of palms and roots development). Experimentation referred to a distribution uniformity of about 88%; considered acceptable for subsurface drip irrigation while it is around 80% for the surface drip irrigation. The results also show an increase in root development and in the number of palm, as well as a substantial water savings due to lower evaporation losses compared to the classic drip irrigation. The results of this study showed that subsurface drip irrigation is an efficient technique, which allows sustainable irrigation in arid areas.

Keywords: Subsurface drip irrigation, Water conservation, Arid areas, Young date palms.

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Authors: Kyoung Hoon Kim

Abstract:

Recently ORC(Organic Rankine Cycle) has attracted much attention due to its potential in reducing consumption of fossil fuels and its favorable characteristics to exploit low-grade heat sources. In this work thermodynamic performance of ORC with superheating of vapor is comparatively assessed for various working fluids. Special attention is paid to the effects of system parameters such as the evaporating temperature and the turbine inlet temperature on the characteristics of the system such as maximum possible work extraction from the given source, volumetric flow rate per 1 kW of net work and quality of the working fluid at turbine exit as well as thermal and exergy efficiencies. Results show that for a given source the thermal efficiency increases with decrease of the superheating but exergy efficiency may have a maximum value with respect to the superheating of the working fluid. Results also show that in selection of working fluid it is required to consider various criteria of performance characteristics as well as thermal efficiency.

Keywords: organic Rankine cycle (ORC), low-grade energysource, Patel-Teja equation, thermodynamic performance

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Authors: Shamima Akhter, Siegfried Bauer

Abstract:

The aim of this study is to analyze the migration  process of the rural population of Bangladesh. Heckman Probit model  with sample selection was applied in this paper to explore the  determinants of migration and intensity of migration at farm  household level. The farm survey was conducted in the central part of  Bangladesh on 160 farm households with migrant and on 154 farm  households without migrant including a total of 316 farm households.  The results from the applied model revealed that main determinants  of migration at farm household level are household age, economically  active males and females, number of young and old dependent  members in the household and agricultural land holding. On the other  hand the main determinants of intensity of migration are availability  of economically adult male in the household, number of young  dependents and agricultural land holding.

 

Keywords: Determinants, Heckman Probit Model, Migration, Rural- Urban.

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Authors: Avinoam Borowsky, Tal Oron-Gilad, Yisrael Parmet

Abstract:

This study examined the role of driving experience in hazard perception and categorization using traffic scene pictures. Specifically, young-inexperienced, moderately experienced and very experienced (taxi) drivers observed traffic scene pictures while connected to an eye tracking system and were asked to rate the level of hazardousness of each picture and to mention the three most prominent hazards in it. Target pictures included nine, nearly identical, pairs of pictures where one picture in each pair included an actual hazard as an additional element. Altogether, 22 areas of interest (AOIs) were predefined and included 13 potential hazards and 9 actual hazards. Data analysis included both verbal reports and eye scanning patterns of these AOIs. Generally, both experienced and taxi drivers noted a relatively larger number of potential hazards than young inexperienced drivers Thus, by relating to less salient potential hazards, experienced drivers have demonstrated a better situation model of the traffic environment.

Keywords: Concept Construction, Hazard Perception, EyeMovements, Driving Experience.

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Authors: Ahmad, A.K., Shuhaimi-Othman, M. Hoon, L.P.

Abstract:

Study was conducted to determine the concentration of copper, cadmium, lead and zinc in Cabomba furcata that found abundance in Lake Chini. This aquatic plant was collected randomly within the lake for heavy metal determination. Water quality measurement was undertaken in situ for temperature, pH, conductivity and dissolved oksigen using portable multi sensor probe YSI model 556. The C. furcata was digested using wet digestion method and heavy metal concentrations were analysed using Atomic Absorption Spectrometer (AAS) Perkin Elmer 4100B (flame method). Result of water quality classify Lake Chini between class II to class III using Malaysian Water Quality Standard. According to this standard, Lake Chini has moderate quality, which normal for natural lake. Heavy metal concentrations in C.furcata were low and found to be lower than the critical toxic value in aquatic plants. Oneway ANOVA test indicated the heavy metal concentrations in C.furcata were significantly differ between sampling location. Water quality and heavy metal concentrations indicates that Lake Chini was not receives anthropogenic load from nearby activities.

Keywords: Cabomba furcata, Heavy metal, Lake Chini, Waterquality

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