• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1294-1303
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• 2009

This paper presents a new numerical algorithm for fault discrimination and fault location estimation when occur to arcing ground and arcing line to line on transmission lines. The object of this paper is developed from new numerical algorithm to calculate the fault distance and simultaneously to make a distinction between transient and permanent faults. so the first of object for propose algorithm would be distinguish the permanent from the transient faults. This arcing fault discrimination algorithm is used if calculated value of arc voltage amplitude is greater than product of arc voltage gradient and the length of the arc path, which is equal or greater than the flashover length of a suspension insulator string[1-3]. Also, each algorithm is separated from short distance and long distance. This is difference to with/without capacitance between short to long distance. To test the validity of the proposed algorithms, the results of algorithm testing through various computer simulations are given. The test was simulated in EMTP/ATP simulator under a number of scenarios and calculate of algorithm was used to MATLAB.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.159-165
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• 2015

Motion control schemes are generally classified into three categories (point stabilization, trajectory tracking, and path following). This paper deals with the problem which is associated with the initial deployment of a group of Unmanned Surface Vehicle (USVs) and corresponding point stabilization. To keep the formation of a group of USVs, it is necessary to set the relationship between each vehicle. A forcing functions such as potential fields are designed to keep the formation and a graph Laplacian is used to represent the connectivity between vehicle. In case of fixed topology of the graph representing the communication between the vehicles, the graph Laplacian is assumed constant. However the graph topologies are allowed to change as the vehicles move, and the system dynamics become discontinuous in nature because the graph Laplacian changes as time passes. To check the stability in the stage of deployment, the system is modeled with Kronecker algebra notation. Filippov's calculus of differential equations with discontinuous right hand sides is then used to formally characterize the behavior of USVs. The stability of the system is analyzed with Lyapunov's stability theory and LaSalle's invariance principle, and the validity is shown by checking the variation of state norm.

• Korean Journal of Community Nutrition
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• v.14 no.3
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• pp.286-294
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• 2009

This study investigated the correlations of five constructs - health concerns, healthy eating practices and attitudes, food choice motives, attitudes toward organic foods - in the formation of behavioral to the purchasing intentions of organic foods. An instrument encompassing health perception, attitudes, habits and personal traits was developed through the comprehensive reviews of the literature and the assured validity and internal reliability of the contents. The questionnaire was administered to the students of three universities at Daegu, Kyungpook province. A total of 288 questionnaires were collected for a response rate of 96.0%. The correlations of five constructs and purchasing intention were tested simultaneously using structural equation modeling. Healthy eating practices and attitudes toward organic foods were found to be the determinants which directly influence the intention to purchase organic foods. Health concerns didn't show direct relation to the purchasing intention of organic foods. The hypothesized path from the health concerns to the purchasing intentions was not supported. The results indicated that food choice motives and healthy eating attitudes should be managed to achieve higher behavioral intention to purchase organic foods.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.3
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• pp.191-199
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• 2020

This study aims to investigate what selection attributes of customer value are more crucial when consumers choose the dessert at convenience store, which is the fastest growing retail format in Korea recently. Factors considered to be important when customers buy dessert, such as economics, diversity, convenience, and safety were examined and also relationship between customer value and satisfaction was analyzed. The survey was conducted through online (including SNS) from April 6, 2019 to April 30, 2019. A total of 303 questionnaires were used for empirical analysis. Factor analysis was performed to verify the validity and reliability of the measured variables. And the structural equation model (SEM) was used as a statistical method for hypothesis testing. As a result, factors as 'diversity', 'safety' were revealed to significantly affect hedonic customer value, while 'convenience' was shown to affect utilitarian customer value significantly. In addition, the path that customer value leads to satisfaction was also found to be significant. The result of the study suggests that selection attributes of convenience store dessert and providing meaningful implications of related hedonic and utilitarian values when customers purchase dessert at convenience store. This study provided practical implications for managers of the fiercely competitive dessert industry.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.28-34
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• 2018

Recently, various engineering approaches have been widely used in the accident investigation field to identify the cause of the accident and to predict damage by accident. Computational analysis is the most commonly used method of accident investigation technique. This technique is mainly used to identify the mechanism of the accident generation and to determine the cause when it is difficult to reproduce the situation at the time of the accident or when it is impossible to perform a reproduction experiment. In this study, The computational fluid dynamics analysis for nitrogen asphyxiation accident generated by defect of building structural between diffusion outlet and cooling tower was performed to determine the inflow path of the suffocation gas, death possibility by concentration of suffocation gas and predicted the time of death due to the accident using 3D modeling and FLACS program. We can quantify diffusion concentration of asphyxiation gas and predict mechanism of death occurrence by accident and evaluate the consequence Analysis through this study. In the future, This method can be widely used in the field of gas safety by improving the reliability and validity of the analysis.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1166-1177
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• 2014

A new type of topology with medium-frequency-transformer (MFT) isolation for medium voltage wind power generation systems is proposed in this paper. This type of converter is a high density power conversion system, with high performance features suitable for next generation wind power systems in either on-shore or off-shore applications. The proposed topology employs single-phase cascaded multi-level AC-AC converters on the grid side and three phase matrix converters on the generator side, which are interfaced by medium frequency transformers. This avoids DC-Link electrolytic capacitors and/or resonant L-C components in the power flow path thereby improving the power density and system reliability. Several configurations are given to fit different applications. The modulation and control strategy has been detailed. As two important part of the whole system, a novel single phase AC-AC converter topology with its reliable six-step switching technique and a novel symmetrical 11-segment modulation strategy for two stage matrix converter (TSMC) is proposed at the special situation of medium frequency chopping. The validity of the proposed concept has been verified by simulation results and experiment waveforms from a scaled down laboratory prototype.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.936-943
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• 2009

In this study, a risk assessment model based on the ETA (Event Tree Analysis) and FTA (Fault Tree Analysis) is developed according to the procedure of hazard analysis and risk assessment in order to estimate the risk quantitatively. The FTA technique is applied to estimate the branch probability (frequency) and the ETA technique is applied to estimate the consequence for each branch path on the ET (Event Tree). A risk assessment model is developed by the combination of those ETA and FTA. In addition, the reliability and the validity of the risk assessment model are verified by comparing the risk estimated through the developed model with the actual equivalent fatality.

• The Journal of Korean Association of Computer Education
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• v.9 no.5
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• pp.31-39
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• 2006

The change into the knowledge based information society requires a transformation of educational paradigm. Accordingly, intelligent learning and distance education are attracting a fair amount of attention. To apply the instructional learning method in this field, we need to consider a individualization of learning, as it were, abstraction of fact and path through learning, which is based on learner's traits, this focus entails a argument for individualized reasoning strategy. Therefore, in this paper, we design a learner's cognitive union, which is based on X-Neuronet(eXtended Neuronet), represent learner's hierarchical knowledge is able to self-learn, and grows adaptive union by proprietor. Additionally, we propose a individualized reasoning strategy, which relies upon learner's cognitive union, and verify the validity.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.2
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• pp.171-177
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• 2004

In this paper, we propose a cognition-based navigational algorithm for mobile robots in dynamic environments. The proposed algorithm consists of two main stages: (i) the fuzzy logic-based perception stage that constructs knowledge from the sensory data for subsequent usage in reasoning, and (ii) the planning stage that identifies the path between a starting and a goal position within its environment on the basis of the knowledge base on the environment and information from the perception stage. A mobile robot reasons places and moves to goal using ambiguous information and ambiguous knowledge through ‘perception’ and ‘planning’. We provide computer simulation results for a mobile robot in order to show the validity of the proposed algorithm.

• Korea Journal of Hospital Management
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• v.23 no.3
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• pp.1-15
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• 2018

Purpose: This study is conducted to identify the impacts of tax exemption on community benefit, policy, human resource management, and public benefit. Based on the results of analysis, we explore several avenues to raise public benefit that is central to the value of existence of non-for-profit hospitals in Korea. Methodology: Survey was formulated referring to the US IRS tax exemption criteria, Form990/Schedule H, and Korean public hospital criteria. A total of 182 survey responses were collected and used to verify measurement validity and perform reliability analysis, confirmatory factor analysis, and path analysis. Findings: The result of this study showed positive relationships among; i) tax development and planning, ii) planning and human resource management, iii) human resource management and policy, iv) policy and community benefit, v) community benefit and public benefit. Practical Conclusion: Tax exemption affects community benefit and public benefit directly as well as indirectly. This implies that expanding tax exemption is likely to improve public benefit mediating community benefit.