• 전력전자학회논문지
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• 제25권6호
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• pp.496-502
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• 2020

The reliability of a solid-state transformer (SST) is one of the important aspects to consider when replacing a conventional low-frequency passive transformer with SST for urban railway vehicles. Lifetime evaluation of SST in the design phase is therefore essential in guaranteeing a certain SST reliability. In this study, a lifetime evaluation of power semiconductor devices in SST is performed with respect to temperature stress. For a case study, a 3 MW SST with three kinds of power modules (one IGBT module and two SiC-MOSFET modules) is used for the lifetime estimation under the operation profile of urban railway vehicles.

• Journal of Periodontal and Implant Science
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• 제8권1호
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• pp.26-26
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• 1978

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.172-176
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• 2000

The paper presents the fault detection and isolation of two DC-DC converters parallel operation by ZCT method. Two experimental prototype converters were designed and implemented for evaluation of fault tolerant system. The experimental results show that fault detection and isolation circuit works very well.

• 실천공학교육논문지
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• 제14권3호
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• pp.513-522
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• 2022

강의평가는 대학교육의 질을 향상시키고 수업을 개선하는데 유용한 정보로 활용된다. 본 연구는 강의평가를 구성하는 요인을 탐색하고자 선행연구와 FGI를 통해 구성요인을 도출하고 계층분석법(AHP: Analytic Hierarchy Process)을 통해 요인간 상대적 중요도 및 우선순위를 파악하였다. 이를 위해 5개의 구성요인과 15개의 평가항목을 도출하였다. 강의평가 요인개발의 전문성과 공정성을 확보하기 위해 학생과 교원을 대상으로 설문을 실시하여 총 20부의 유효한 자료를 수집하였고, 일치도 검증을 완료한 자료를 토대로 각 평가항목의 가중치를 산출하였다. 분석 결과 강의평가 요인구성에 있어서 학생은 수업 내용, 수업 방법, 수업 운영, 수업 평가, 수업 계획 순으로, 교원은 수업 내용, 수업 운영, 수업 방법, 수업 평가, 수업 계획 순으로 중요하다고 평가하였다. 본 연구 결과를 바탕으로 대학교육의 질 관리 차원에서 강의평가의 효율성과 신뢰성 향상을 위해 다양한 분석과 연구가 있기를 기대한다.

• 한국도서관정보학회지
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• 제50권1호
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• pp.293-312
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• 2019

본 연구의 목적은 현재 참여율이 날로 저조해지고 있는 학교도서관 운영평가의 개선 방안을 모색하기 위해 평가의 변화 추이와 평가 참여 인력의 인식을 조사하는 데 있다. 이를 위해 학교도서관 운영평가 참여율, 지표 변화 추이 등을 문헌조사로 분석하고 학교도서관 운영평가에 대한 전국 학교도서관 전담인력의 인식을 질문지법으로 조사하였다. 학교도서관 운영평가 참여율은 09년에 22.2%로 최고치를 기록한 이래 17년 7.2%까지 낮아졌다. 학교도서관 운영평가의 양적 평가 방법으로의 타당도 인식은 2.84점, 질적 평가 방법으로의 타당도는 2.97점으로 조사되었다. '연간 운영 계획 수립'에 대한 평가지표 타당도 인식 평균은 3.90점으로 가장 높게, '지역사회 봉사'는 2.27점으로 가장 낮게 조사되었다. 평가 미참여 이유에 '학사 업무 처리가 바빠서'의 평균이 가장 높게 조사되었다. 학교도서관 운영평가에 대해 낮은 인식이 조사된 바, 평가지표 및 참여 방법 등에 대한 개선책을 모색하고 학교도서관 전담인력의 인식 개선을 이룰 수 있는 정책 마련이 병행되어야 하겠다. 더불어 평가 운영주체는 평가의 결과를 다시 학교도서관 정책에 반영할 수 있도록 노력해야 할 것이다.

• 대한지역사회영양학회지
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• 제9권2호
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• pp.233-240
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• 2004

This study was design to grope the suggestions leading synergic effects by bridging the gap between headquarters and branch office, and so to identify the infra-system of contract foodservice management company (CFMC) necessary for operating any kind of branch office including school, hospital and business and industry (B＆I). Among 8 categories consisted of infra-system in CFMC, 'C8. Evaluation ＆ analysis for branch office's operation' was the most important category in the headquarter's viewpoint, while 'C3. Sanitation management system' was the most important category in branch office's viewpoint. In support and application, 'C3. Sanitation management system' was the highest category in both headquarters and branch offices including school, hospital and B＆I. As a result of analysis on gap between main and branch office in importance, support and application in 8 categories, the efforts of communication and community of perception for infrastructure were needed, because 'C4. Education ＆ training for human resource management (HRM) system' and 'C8. Evaluation ＆ analysis for branch office's operation' in importance, 'C2. Menu management system', 'C4. Education ＆ training for HRM system', 'C6. Facility ＆ utility support system' and 'C8. Evaluation ＆ analysis for branch office's operation' in support had a gap. Correlation analysis to grasp the relation between importance of infra-system and headquarters' support or branch office's application showed that headquarters's importance and support were correlated positively in 'C3. Sanitation management system', 'C6. Facility ＆ utility support system', 'C7. Customer satisfaction management system' and 'C8. Evaluation ＆ analysis for branch office's operation' and branch office's importance and application were correlated positively in 'C1. Procurement ＆ food processing system', 'C5. Management Information system', 'C7. Customer satisfaction management system' and 'C8. Evaluation ＆ analysis for branch office's operation'. Lastly, 'C6. Facility ＆ utility support system' in the branch office of school and hospital and 'C2. Menu management system' in the branch office of B＆I were high in importance, low in support and application, therefore Intensive support for these categories was needed. In conclusion, continuous check and improvement for categories, which were identified as an urgent problems to be solved in this study, among infra-structure qualifying for CFMC, would enable contract foodservice industry that has grown quantitatively till now to grow qualitatively.

• 산업경영시스템학회지
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• 제34권1호
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• pp.1-8
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• 2011

Controlling industrial vehicle operated by human in warehouse was not simple since the information transfer for controlling the vehicle was not easy. However, as the technology for the WMS (Warehouse Management System) has been advanced and the PDA (Personal Digital Assistant) has come into wide use in a workplace, the control of man-operated vehicle became less difficult as do to AGVS (Automated Guided Vehicle System). This study examines the ways to improve the efficiency of warehouse operation through introducing rule of task assignment for the vehicles, particularly forklift. This study, basically, refer to AGV operation policy because a great number of studies for AGV dispatching rule have been done and the mechanism for the controlling vehicles is very similar. The workers in field prefer to simple dispatching rules such as Shortest Retrieval Time First (SRTF), Shortest Travel Time First (STTF), and Longest Waiting Time First (LWTF). However, these rules have potential disadvantage. Thus, several rules made up by combining rules mentioned above are introduced and these new rules use threshold value or evaluation formula. The effectiveness of these new rules are tested by simulation and the results are compared. This study proposes favorable dispatching rules for forklift in warehouse for the efficiency of the vehicle operation and stability of service level.

• 전기학회논문지
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• 제64권6호
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• pp.857-863
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• 2015

OF cable with excellent reliability and economic efficiency, has been used as the main cable of underground transmission in Korea. However, as XLPE cable is excellent in view points such as reduction of loss, convenience on the construction/operation, and manufacturing technology, it has been replaced as instead of OF cable. Also, when the aging occurs in some sections of OF cable, the section is replaced as XLPE cable without changing of whole cable line. However, there are some differences like electrical constants between both types of cables. Therefore if underground transmission system will be operated as combined connection composited of both cables, it should be proved that overvoltage is stable in steady and transient state. This paper describes the effectiveness of connection operation in combined OF and XLPE cable. For the evaluation of effectiveness, some important analysis such as sheath component voltage, lightning and switching overvoltage, single line-to-ground fault are carried out in steady and transient state. EMTP/ATPDraw is used for modeling and analysis of system.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2002년도 춘계 국제 학술대회
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• pp.54-64
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• 2002

This study evaluated advanced water treatment (AWT) system in Korea. There are currently 16 plants operating with AWT. However, no attempt has been made to evaluate AWT system. This study selected one water treatment plant with AWT (pre-ozonation ＋ BAC). Using the operation data from 1995 to 2001 and pilot study results, the post-evaluation of the AWT system has been conducted. The study found that AWT improved water qualities of organic, ammonia, and turbidity, as expected. However, the extent of the improvement was generally short of the pilot study expectations. Pre-ozonation failed to decrease coagulant consumption. The dosage increased rather than decreased. AWT was, however, successful to decrease chlorine consumption. The chlorine reduction was related to the change in raw water characteristics and AWT introduction. Pre-ozonation failed to decrease coagulant consumption. The dosage increased rather than decreased. AWT was, however, successful to decrease chlorine consumption. The chlorine reduction was related to the change in raw water characteristics and AWT introduction, Both operation of pre-ozonation and reduced ammonia loading were responsible for the reduction. AWT increased the operation cost. Maintenance, raw water, and power cost increased, while labor and chemical cost decreased. Manpower reduction resulting form automation caused the decrease of labor cost. The reduction of chlorine consumption caused the decrease of chemical cost.

• 해양환경안전학회지
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• 제12권4호
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• pp.233-239
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• 2006

본 연구는 우리나라 RCC/RSC의 효율성을 2개의 투입자료와 4개의 산출자료를 이용하여 DEA법을 이용하여 측정하였고, 정성적 자료는 전문가의 설문 및 면접결과로 평가하였다. 또한, 이러한 자료를 통합하기 위한 방법은 의사결정지원시스템인 퍼지로직을 적용하였고, 이 평가방법을 이용하여 RCC/RSC의 운영효율성의 우선순위를 평가하였다. 그 결과 목포, 제주, 부산, 통영, 인천, 여수, 동해, 울산, 포항, 속초, 태안, 완도, 군산RSC 순으로 효율성이 높은 것으로 나타났다.