• Journal of Power Electronics
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• v.16 no.3
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• pp.861-871
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• 2016

With high penetration of renewable energies, power electronic transformers (PETs) will be one of the most important infrastructures in the future power delivery and management system. In this study, an isolated bidirectional modular multilevel DC/DC converter is proposed for PET applications. A modular multilevel structure is adopted as switching valves to sustain medium voltages to achieve modular design and high reliability. Only one high-frequency transformer is used in the proposed converter, which significantly simplifies the circuit and galvanic insulation design. A dual-phase-shift modulation strategy is proposed to regulate the output power and achieve a simple voltage balancing control. A down-scaled (2 kW/20 kHz) prototype is constructed to demonstrate the proposed converter and verify the control strategy. The experimental results comply with the theoretical analysis well, with the highest power efficiency reaching 97.6%.

• Journal of the Korea Society of Computer and Information
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• v.6 no.3
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• pp.137-142
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• 2001

Electronic Commerce are facing on social upheavals by a rapidly advanced Open Network such as Internet, and the crest of a digital boom in the economic side for the 21th century. As the Internet develops into a robust delivery channel for commerce, it will be important to understand the characteristics of on-line markets. This paper addresses price competition in Internet Electronic Commerce by reviewing current academic research, discussing the implications of price competition, and proposing areas for future study.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.38-50
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• 2023

Proton exchange membrane fuel cell (PEMFC) is a portable and clean power generation device. The structural arrangement of the flow field has a significant influence on the delivery efficiency of PEMFC. In this article, a new bionic flow channel is designed based on the inspiration of a spider shape. The branch channel width and branch corner are studied as the focus, and its simulation is carried out by the method of computational fluid dynamics (CFD). The results show that when channel width/rib width and corner of the branch are 1.5 and 130° , respectively, it is the best numerical combination and the cell comprehensive performance is excellent. The final model using this numerical combination is compared with the traditional flow channel model to verify the advancement of this scheme.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.707-710
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• 2007

모바일 단말이 이종네트워크 환경에서 멀티미디어 데이터를 스트리밍 수신 받으며 이동하는 경우, 특성이 다른 링크로 옮겨감에 따라 링크의 적정 대역폭에 맞지 않은 스트림 전송률 때문에 전송 성능이 떨어진다. 본 논문은 Mobile IPv6 에서의 링크 특성 정보 전달방법을 이용하여 스트리밍 전송 성능을 높일 수 있음을 보인다. 이를 위해서 실제로 링크 특성 정보 전달 방법이 적용된 Mobile IPv6 테스트 베드를 설계하여 MN 에 링크 특성 추출 기능을 구현하였고, CN 에 데이터 전송율을 조절할 수 있는 UDP 스트리밍 서버 기능을 구현하였다. 스트리밍 데이터를 수신하는 MN 이이종 네트워크 환경간을 핸드오버할 때에 전송 성능이 향상됨을 실험을 통하여 보인다.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.435-448
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• 2004

While Internet promises ubiquitous access, it also creates a fundamental challenge to the traditional ownership toward digital assets traded in e-commerce market. Sharing digital information freely through shared networks leads to many untapped business opportunities, but uncontrolled digital asset transaction undermines many electronic business models. Thus, in this Internet age, proper protection and safe delivery of Intellectual Property (IP) and its representation as digital assets would be a crucial ingredient of building trust in upcoming e-business environment. In this paper, we give a general structural diagram of Intellectual Property Management and Protection (IPMP) and implement an IPMP prototype based on the RSA encryption algorithm and XrML (eXtensible rights Markup Language) WORK tags to show how proper protection and safe delivery of the intellectual property is achieved. This study concludes that IPMP mechanism may contribute significantly to the volume and quality of e-commerce market.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.198-201
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• 2001

Recently the wireless-internet has been spreading extensively. People are spending a large part of their time gaining access to information using a mobile device. With the rapid growth of on-line Electronic Commerce, the use of mobile devices creates a new paradigm that provides users with location-independent real time service. Although this new paradigm does have some advantages, limited process speed, low bandwidth, the low battery capacity of mobile devices, and a high rate of wireless network errors causes many overhead expenses during service time with the server. In this paper, we suggest an autonomous service delivery system, which provides mobile agent capability to users that cannot maintain a connection. We have developed the system based on java mobile agent technology. Using this system, we can provide more effective service to users when the user is sending requirements for service through a mobile device that has limited resources. Furthermore we can manage the contact server dynamically when new services are added.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.184-187
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• 2001

The purpose of this study is to find the perceived risk which influences consumers' purchase attitudes so that consumers' participation in electronic commerce could be enhanced. Consumer behavior involves risk in the sense that any action of a consumer will produce consequences which one cannot anticipate, and some of which are at least likely to be unpleasant. The types of perceived risks are financial risk, performance risk, social risk, psychological risk, time loss, opportunity loss, privacy risk, fashion loss, delivery risk, seller's response risk and seller's fraud risk The findings are as follows: $\circled1$ The financial risk, performance risk, time loss, delivery risk, seller's response risk and seller's fraud risk have negative effects on the consumers' purchase attitudes. $\circled2$ There is no difference in the level of perceived risk according to the demographic factors such as age, education and income level.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.614-619
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• 2007

The importance of simulation of plastic flow in the injection mold is increasing as the parts are more complex, but the small-scale enterprises can't afford to invest for the infra individually. CAE (Computer Aided Engineering) service was naturally born based on these needs. This paper presents the engineering collaboration model between the large and the small/medium enterprises in the field of injection molds. Based on the engineering collaboration hub and CAE service, small-scale enterprises could research the necessary technology and develop the proper products. The analysis results of CAE are provided by the integrated visualization system on the web. This paper also deals with the delivery shorting process of CAE service for electric/electronic parts which should meet the needs of customers as soon as possible.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.40
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• pp.147-167
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• 2008

This paper investigates changing business transaction under the e-commerce environment and their implications on freight transport industry with some case studies. It shows that an efficient and reliable delivery system is essential for e-commerce as business industries are faced with the stricter and more diversified demands of customer. In addition, many aspects of business practices such as small batch, customized production and just-in-time distribution in the e-commerce environment, in turn, bring about a number of changes in the volume and service patterns of freight transport. E-commerce requires longer transport distances and often higher delivery frequencies. It also entails to a certain extent a modal shift towards truck and air freight transport modes. On the one hand, the logistical requirements of e-commerce goods may stimulate greater complexity in existing supply chain management, causing higher costs. However it is true that the increased visibility of goods through more efficient information flow allows more efficient and effective transport management in the logistics system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.87-97
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• 2005

This study deals with the analysis on the consciousness and image character of the internet shopping mall. As consciousness analysis result of internet shopping mall consumer, 'cheap price' and 'convenience' are evaluated high by reason that buy goods/service. 'Delivery delay' shows that deficiency of swiftness is indicated preferentially by shortcoming when the goods/service are purchased at the internet shopping mall. Consumer is prferring most 'deferred payment' with consumer's protection system of internet shopping mall. In image character of internet shopping mall, computer system speed and swiftness of reaction time, intimacy of shopping mall site design, delivery system trustability, goods/service contiguity, trustability of billing system, recognition shopping mall company, consistency about good service etc., showed high assessment, but comparative satisfaction is not high in solution at authoritativeness of personal information leakage prevention, problem occurrence.