• 제목/요약/키워드: Variable switching frequency

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150kW급 수소연료전지 차량용 DC/DC 컨버터 개발 및 실차모사 실험 (Development of DC/DC Converters and Actual Vehicle Simulation Experiment for 150 kW Class Fuel-cell Electric Vehicle)

  • 김선주;정현주;최세완;조준호;전유종;박준성;윤혜성
    • 전력전자학회논문지
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    • 제27권1호
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    • pp.26-32
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    • 2022
  • This paper proposes a power system that includes a 120k W fuel cell DC-DC converter (FDC) and 30 kW bidirectional DC-DC converter (BHDC) for a 150 kW fuel-cell vehicle. With a high DC link voltage of 800 V, the efficiency and power density of the power electronic components are improved. Through the modular design of FDC and BHDC, electric components are shared, resulting in reduced mass production costs. The switching frequency of 30 kHz of full SiC devices and optimal design of coupled inductor reduce the volume, achieving a power density of 8.3 kW/L. Furthermore, a synergetic operation strategy using variable limiter control of FDC and BHDC was proposed to efficiently operate the fuel cell vehicle considering the fuel cell stack efficiency according to the load. Finally, the performance of the prototype was verified by Highway Fuel Economy Driving Schedule testing, EMI test, and the linked operation between FDC and BHDC. The full load efficiencies of the FDC and BHDC prototypes are 98.47% and 98.74%, respectively.

미국자동차시장의 구조분석 (Market Structure Analysis of Automobile Market in U.S.A)

  • 최인혜;이서구;이성근
    • 마케팅과학연구
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    • 제18권1호
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    • pp.141-156
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    • 2008
  • 본 연구는 미국의 자동시장의 시장구조를 분석한 것이다. 자동차 시장의 구조분석는 제품의 특성이 냐내구재라는 점에서 의의가 있다. 그 동안 시장구조분석은 일반포장소비재를 중심으로 분석되어 왔으나 자동차의 시장구조분석는 자동차의 구매주기가 장기간이며, 다음 구매는 많은 소비자가 상위차급으로 이동한다는 점에서 기존의 분석에 사용되었던 상표전환자료를 사용하는데 한계가 있다. 이 때문에 본 연구에서는 구매고려상표군을 중심으로 우사성지수로 사용하여 시장구조분석을 하였다. 자료는 미국의 자동차구매에 관한 이차자료를 활용하였으며, 자료의 특성상 일부차종에 한정하여 사용하였다. 크게 세가지 형태-비용, 비용-형태, 비구조화의 가설적 시장을 비교분석하였으며, 결과적으로 형태-비용 구조가 가장 우수한 것으로 판단되었다.

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옴니채널의 지각된 편리성과 유용성이 옴니채널 사용과 소비자-브랜드 관계에 미치는 영향 (Omnichannel's Perception Effect on Omnichannel Use and Customer-Brand Relationship)

  • 임덕순;한상설
    • 유통과학연구
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    • 제14권7호
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    • pp.83-90
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    • 2016
  • Purpose - This study focuses on new type distribution channel that named as Omnichannel. Omnichannel is developed from Multichannel which is used in many distribution channels to buy or selling goods. Omnichannel basically needs an Information and Communications Technologies(ICT) to use, so researcher conduct a Technology Acceptance Model(TAM) to research model. Customer-brand relationship was used as dependent variable to focus on the role of Omnichannel. Research design, data, and methodology - The subject of this study is customer who purchase goods or service through omnichannel. Based on the literature from the preceding research analysis of TAM and customer-brand relationship, this study was constructed by the reference to previous studies, final research model design for figure out casual relationship among perceived ease of use, perceived usefulness, omnichannel use and customer-brand relationship. From 2016 February 3 to March 17, questionnaire survey targeted customers who use online and offline channels. 273 questionnaire survey had conducted, then, 252 survey data were available for empirical analysis. Researcher provide descriptive statistics for checking generality. Cronbach's alpha value was used to check the reliability of data. Exploratory factor analysis was used for purification of values and eigenvalue checking. After EFA, Confirmatory factor analysis was used to prepare structural equation modeling with executing structural equation modeling for confirming hypothesis which developed by researcher. Results - The main results of this empirical study are as follows. First, omnichannel's perceived ease of use has positive significant effect on perceived usefulness(estimate: 0.579). Moreover, omnichannel's perceived ease of use and perceived usefulness has positive significant effect on omnichannel use(estimate: 0.325,0.648). Second, using omnichannel has positive significant effect on brand-customer relationship(estimate: 0.521). Every hypothesis adopted as researcher designed. This study found out the intermediate relationship between perceived ease of use and omnichannel use by investigating hypothesis. Conclusions - Base on the empirical result, this study confirmed that TAM theory perceived has relation with omnichannel. First, factors of TAM has positive effect on omnichannel use, so it highlights the important role of customer based interface and usefulness. Especially, perceived usefulness has high indirect influence on ease of use and use of omnichannel. It seems that when customers try to decide use or not use omnichannel, customers focus on percept benefits from omnichannel. Thus, a provider should applicate attractive price table, accurate product or service information and high switching cost strategy to emphasize the usefulness of omnichannel. Second, using omnichannel enhances the relationship between customers and brand, because there are more time and frequency to serve customers. It is important because good relationship between customers can increase the future's financial performance through word of mouse, positive brand image and loyalty to brand or company. Finally, despite of empirical result and implications, this study has limitations. First, there are only a few previous studies about omnicahnnel, so literature reviews are restricted. While set up the factors which can affect the use of omnichannel, next study should be considered with broader theories or models(ex: contingency theory). Second, omnichannel has developed from multichannel, so comparative analysis is needed between these methods because there is a possibility about different forte character of each distribution system on customer's consuming patterns.