• Journal of the Korean Society of Safety
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• v.22 no.1 s.79
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• pp.61-66
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• 2007

Car crashes are the leading cause of death for persons of every age. Specially, human-related factor has been known to be the primary causal factor of such crashes than vehicle-and environmental-related factors. There are various studies to analyze driver's behavior and characteristics in driving for reducing the car crashes in many areas of car engineering, psychology, human factor, etc. However, there are almost no studies which analyze mainly the human errors in driving and estimate their probabilities in terms of human reliability analysis. This study estimates the probability of human error in driving, i.e. driver error probability. First, fifty driver errors are investigated through DBQ (Driver Behavior Questionnaire) revision and the error likelihoods in driving are collected which are judged by skillful drivers using revised DBQ. Next, these likelihoods are converted into driver error probabilities using the results that verbal probabilistic expressions are changed into quantitative probabilities. Using these probabilities we can improve the warning effects on drivers by indicating their driving error likelihoods quantitatively. We can also expect the reduction effects of car accident through controlling especially dangerous error groups which have higher probabilities. Like these, the results of this study can be used as the primary materials of safety education on drivers.

• Journal of Power Electronics
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• v.5 no.3
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• pp.198-205
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• 2005

The mechanical system of a drive can often be modeled as a two- or three-mass-system. The load is coupled to the driving motor by a shaft able to perform torsion oscillations. For the automatic tuning of the control, it is necessary to know the mathematical description of the system and the corresponding parameters. As the manpower and setup-time necessary during the commissioning of electrical drives are major cost factors, the development of self-operating identification strategies is a task worth pursuing. This paper presents an identification method which can be utilized for the assisted commissioning of electrical drives. The shaft assembly can be approximated as a two-mass non-rigid mechanical system with four parameters that have to be identified. The mathematical background for an identification procedure is developed and some important implementation issues are addressed. In order to avoid the excitation of the system with its natural resonance frequency, the frequency response can be obtained by exciting the system with a Pseudo Random Binary Signal (PRBS) and using the cross correlation function (CCF) and the auto correlation function (ACF). The reference torque is used as stimulation and the response is the mechanical speed. To determine the parameters, especially in advanced control schemes, a numerical algorithm with excellent convergence characteristics has also been used that can be implemented together with the proposed measurement procedure in order to assist the drive commissioning or to achieve an automatic setting of the control parameters. Simulations and experiments validate the efficiency and reliability of the identification procedure.

• Journal of Power Electronics
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• v.15 no.1
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• pp.256-267
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• 2015

Grid-connected transformerless photovoltaic (PV) inverters (TPVIs) are increasingly dominating the market due to their higher efficiency, lower cost, lighter weight, and reduced size when compared to their transformer based counterparts. However, due to the lack of galvanic isolation in the low voltage grid interconnections of these inverters, the PV systems become vulnerable to leakage currents flowing through the grounded star point of the distribution transformer, the earth, and the distributed parasitic capacitance of the PV modules. These leakage currents are prohibitive, since they constitute an issue for safety, reliability, protection coordination, electromagnetic compatibility, and module lifetime. This paper investigates a wide range of multi-kW range power rating TPVI topologies and classifies them in terms of their leakage current attributes. This systematic classification places most topologies under a small number of classes with basic leakage current attributes. Thus, understanding and evaluating these topologies becomes an easy task. In addition, based on these observations, new topologies with reduced leakage current characteristics are proposed in this paper. Furthermore, the important efficiency and cost determining characteristics of converters are studied to allow design engineers to include cost and efficiency as deciding factors in selecting a converter topology for PV applications.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1788-1790
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• 2003

GIS is a typical power equipment with higher reliability. It is compact and safe because all the energized parts are enclosed by a sealed cylindrical tank which is filled with $SF_6$. Generally gas insulated power equipments like GIS are designed to have sufficient electrical strength to prevent partial discharges under normal operating condition. Despite of the careful processes in manufacturing, transporting and assembling, voids or particles can be created, resulting in partial discharges at electrically weak points. The key factors causing partial discharges in GIS are; particles, voids in solid insulation, protrusions, poor contact of metal components, etc. The particle can be attached on; spacers, electrodes, internal wall of the GIS tank. It also moves in GIS freely. Most of partial discharges are likely to occur when particles are attached to spacers. In this paper, the electrical characteristics of a surface discharge were investigated under various conditions by using simulation program of FEMLAB.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.7
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• pp.1075-1084
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• 2007

The purpose of this study is to find out the important factors and efficient strategies concerning internet marketing. This study tries to examine satisfaction of the on-line consumers on internet shopping mall via fashion products. To fulfill this objectives, a survey was conducted from May 15 to May 30 in 2006, and an subject of study is men and women aged from 10s to 40s in purchase experience of the fashion merchandise to internet shopping malls. Data collected over the internet, and analyzed the 205 subjects. The statistical analysis methods was frequency analysis, reliability analysis, factor analysis, multiple regression analysis. The empirical studies were summarized as follows. First, internet shopping mall's fashion goods attributes(goods characteristics, aesthetic expression, variety of goods) significantly affect consumer's utilitarian shopping value. Second, internet shopping mall good's price attributes(economical efficiency of price, price reasonableness, price value, price information, price discount) significantly affect consumer's shopping utilitarian shopping value and hedonic shopping value. Third, consumer's utilitarian shopping value and hedonic shopping value are positively related to the internet consumer's shopping satisfaction.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.9
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• pp.1450-1460
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• 2008

The goal of this study was to investigate the impacts of service quality, customer satisfaction, and switching burier on store loyalty of the clothes shops at large-scale discount stores. The subjects were 357 female adults living in Suncheon City, Jeollanam Province. The questionnaires were conveniently sampled from June 1 to 30, 2006. The collected data were factor and reliability analyzed using the SPSS program. And Regression was used to verify the relationships between the variables. Among the six hypotheses set in the research model, total three were accepted through empirical analysis and the rest three were accepted partially. The empirical results showed the following managerial implications. First, consumer' perceived service quality has relationship with customer satisfaction and store loyalty. Second, service quality has a positive relationship with switch barrier. Third, customer satisfaction has significantly related with switch barrier. Fourth, switch barrier has positively related with store loyalty. Finally, 'sales people', 'VMD/atmosphere', and 'assortment' of the service quality factors have positive relationships with store loyalty, but 'policy' has a negative relationship with store loyalty.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.723-726
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• 2008

It is not always easy to estimate the parameters in hydrologic models due to insufficient hydrologic data when hydraulic structures are designed or water resources plan are established, uncertainty analysis, therefore, are inevitably needed to examine reliability for the estimated results. With regard to this point, this study applies a Bayesian Markov Chain Monte Carlo scheme to the NWS-PC rainfall-runoff model that has been widely used, and a case study is performed in Soyang Dam watershed in Korea. The NWS-PC model is calibrated against observed daily runoff, and thirteen parameters in the model are optimized as well as posterior distributions associated with each parameter are derived. The Bayesian Markov Chain Monte Carlo shows a improved result in terms of statistical performance measures and graphical examination. The patterns of runoff can be influenced by various factors and the Bayesian approaches are capable of translating the uncertainties into parameter uncertainties. One could provide against an expected runoff event by utilizing information driven by Bayesian methods. Therefore, the rainfall-runoff analysis coupled with the uncertainty analysis can give us an insight in evaluating flood risk and dam size in a reasonable way.

• Archives of design research
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• v.12 no.2
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• pp.121-130
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• 1999

The purpose of this study is to provide standardization on the examination that could measure students' diagrammatic creativity at design college. For this purpose, we tested college students, who was selected by educational system, regional, and grade groups to use the examination, and suggested the standardization criterion by analyzing these data. The data analysis procedures of this study consist of three step, the first that was to investigate the goodness of the examination paper, second step was to measure the reliability and the validity for the goodness of questions, the last step was to suggest the standardize scores for standardization on the examination. The results of the goodness and standardization analysis showed three structural factors(fluency, flexibility, originality) of this examination were proper to measure the diagrammatic creativity, and the proposed examination tool seemed to be good enough to apply in practice.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.136-144
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• 2004

Dissolved gas in oil analysis has been used for fault diagnosis of oil immersed insulation. In this paper to improve the reliability in deciding the degradation causes of the oil immersed insulation, we carried out electrical and thermal degradations for the insulations, and analyzed the characteristics of dissolved gases distribution on each situation. As a result more reliable faults discrimination is possible if we use the interrelation of factors like key gases and gas compositions of hydrocarbon gases and ratios of CO/$CO_2$.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.42-47
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• 2003

To prevent major accident from toxic gas release, explosion, or fire in chemical processes, it needs dynamic control of human error with mechanical failure. Although most of major accidents occur with a coupling of human error and mechanical failure, numbers of researches have studied human error and mechanical reliability independently, but no where cross each other, to reduce the risk in the process. This work focuses on the coincidence of human error and mechanical failure for management of human error, and on some important performance shaping factors to propose a method for improving safety effectively of the process industries.