• Journal of Power Electronics
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• v.7 no.3
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• pp.203-212
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• 2007

In this paper, a proposed approach to improve the power factor of three-phase rectifiers and to stabilize the output voltage against load change is presented. The elements of the given control strategy are small size, low cost, high performance, and simplicity. The proposed control strategy of switches is based on a prototype of three bi-directional switched consisting of four diodes and one IGBT. A control technique and operational procedure are also developed, both theoretically and experimentally. The experimental results clearly verify the theoretical analysis from the prototype connected to grid unity.

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.1
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• pp.16-27
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• 2009

The purpose of this study was to develop of learning strategy scale for college students. This study further classified several sub-areas and defined each concepts of learning strategy. Based upon the classification of each sub-areas, tentative test items were developed through the verification of validity by three professionals. A pilot study of the developed scale was administered to 239 college students. And the research collected major data from 1,012 college students. Data were analyzed to obtain item quality, reliability, and validity analysis. The results of this study were as follows. The scale for learning strategy was defined by eight factors and they were 'self-management strategy', 'examination-readiness strategy', 'cognitive strategy', 'memorizing strategy', 'reporting strategy', 'resource-utilization strategy', 'self-regulated strategy', 'cooperative learning strategy'. The results of the confirmatory factor analysis proved the eight factors in the learning strategy. And criterion validity evidence was also obtained from a correlation analysis of the level of academic achievement.

• East Asian mathematical journal
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• v.33 no.1
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• pp.23-36
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• 2017

We study an optimization problem for HARA utility function under a multi-scale Heston's stochastic volatility model. We investigate a practical strategy that do not depend on the incorporated factor which is unobservable in the market.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.924-931
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• 2008

This paper presents a buswise transmission loss allocation algorithm utilizing the transaction strategy. We prove that whatever calculated by any transaction strategy, the total of the allocated transmission losses of each bus, including no-load loss allocation, almost equals the total loss of AC power flow algorithm and the loss is perfectly slackbus-independent. In this paper, the allocated transmission losses of each bus is calculated by the method of integrating loss sensitivities using by the load level parameter ${\lambda}$. The performance of the proposed algorithm is evaluated by the case studies carried out on the WSCC 9-bus and IEEE 14-bus systems.

• Journal of Korean Port Research
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• v.9 no.1
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• pp.1-17
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• 1995

According to the analysis results, first, the purpose of information system is usually internal-oriented (decrease of employees and increase of productivity) in the port-logistics industry. Second, the success factor of information system for internal strategy group is different for its external strategy group. Third, the external enviornment factors affect on the information strategy and the success factor in the port-logistics industry. Therefore, I think that it is necessary for the port-logistics industry to consider the information strategy direction and its affecting factors in the port-MIS.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.169-176
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• 2007

In this paper, we suggest the IT industry complex strategy based on previous study on the success factor and success strategy for the promotion of IT industry in Yongin city. The strategy factors are evaluated by the three groups(IT firms, local government official worker, professor) which have an influence on IT policy, and the priority and important rate of strategy analyzed by AHP. The results of this research extracted through expert inquiry and survey contribute to assist planners and policy-makers in supporting IT industry by providing useful information about the suggested strategy.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.263-266
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• 2003

The high power factor converters are classified step-up, step-up-down and step-down converter, The power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. And the power system brings on a high efficiency and high power factor. When a switch of the step down converter is operated with a commercial frequency(60Hz), a reactor using the converter is gone with a great number of harmonics waveforms of low grade. As results of this, the converter is decreased input power factor and is increased system size. To improved these, this paper proposes a PSM(Pulse Size Modulation) control strategy operated with high power factor.

• Journal of Information Technology Applications and Management
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• v.9 no.4
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• pp.179-204
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• 2002

The purpose of this study is to empirically Investigate the critical success factors affecting the participation of B2B e-marketplace from a perspective of buyers and sellers. The research model presented in this study suggests that the success of B2B e-marketplace depends on the degree of participation of buyers and sellers. It is hypothesized that the participation of buyers and sellers is related with several contextual factors. The contextual factors included: (a) industry and market factor; (b) Internal environment factor; (c) product factor; (d) Inter-organizational factor; and (e) B2B e-marketplace system and strategy factor. An analysis of data from 31 buyer firms and 31 seller firms reveals that those five factors have a significant effect on the participation and success of B2B e-marketplace. The implications of the study are discussed and further research directions are proposed.

• Information Systems Review
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• v.1 no.2
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• pp.137-152
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• 1999

• Journal of the Korean School Mathematics Society
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• v.15 no.3
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• pp.487-509
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• 2012

This study, in order to contribute to improvement of the affective domain for mathematics which is one of the largest issues of mathematics education, examined the background variables influencing mathematics anxiety of middle/high school students. As the result, the middle school students showed a greater level of anxiety than the high school students did, and especially the anxiety level according to environment factor and learning strategy factor was high. Also, male students showed overall a greater mathematics anxiety than female students did, and both group of students showed a higher anxiety level according to environment factor and learning strategy factor. Besides, the greater the time spent on private education was, the higher the mathematics anxiety level, and in test/performance factor, the group with low self-initiated learning time showed a higher level of mathematics anxiety compared to other two groups. Among four subfactors of mathematics anxiety test, the students overall scored lowest in anxiety for test/performance factor, and highest in environment factor.