• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.296-299
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• 2003

The conventional DTC strategy provides a fast torque response even though it has very simple scheme consisted with only two hysteresis band comparators and a switching table for torque and flux control. Drawbacks of the conventional DTC are relatively high torque ripple at low speed and variation of the switching frequency according to motor speed. In this paper, the new direct torque control(DTC) schemes are proposed. Those schemes are based on the torque slope and enable to reduce the torque ripple and maintain the switching frequency constantly.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.246-252
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• 2011

In this paper proposes the soft-switching boost converter and MPPT control for improving the efficiency of PV system. The proposed converter designed H-bridge auxiliary resonant circuit. By this circuit, all of the switching devices perform the soft switching under the zero voltage and zero current condition. Therefore the periodic switching losses can be decreased at turn on, off. The soft switching boost converter designs for 1.5[kW] solar module of the power conversion. Thus, this soft switching boost converter is simulated by MATLAB simulation using Newton-Method algorithm. As a result, Proposed Soft Switching Converter compared to a typical boost converter switching loss was reduced about 61%. And the overall system efficiency was verified to increase about 3.3%.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.142-147
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• 2009

Conventional HP(high pressure) sodium or Metal-halide lamps have a life span of around one year requiring at least annual replacement and maintenance. High Power LED lights require no regular maintenance further increasing savings on replacement bulbs, access equipment and labour costs. New installations benefit from a substantial reduction in the cost of expensive heavy duty cable required for sodium lighting. Especially, LED light can achieve variable color temperature, high functional performance in the field of street light. There are two main method to achieve variable color temperature function of the street light. one method is using RGB multi-chip LED, the other is using Orange-White LED method. In this paper, it was compare RGB Multi-chip LED with white-orange LED for there characteristics performance.

• Journal of Korean Library and Information Science Society
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• v.37 no.3
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• pp.209-234
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• 2006

In this study, I examined the current situation of the reading instruction policy and the entity of the arguments and criticism surrounding the reading instruction policy. In addition, on the basis of this research I analyzed the problems of the reading instruction policy. Moreover, I suggested for the desirable direction and alternative of the reading instruction policy and the reading instruction.

• Journal of Korean Library and Information Science Society
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• v.10
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• pp.59-94
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• 1983

Through the close examination of characteristics of adolescent, social institutions and its programs, and newly added and expanded library reference services. it is founded that new role and qualifications of young adult reference librarians are prerequisite subject. The following are the summary of new role and qualifications of specialized young adult reference librarianship. 1. Adequate training and education for the YA librarians is needed in order to have understanding of their characteristics (physiology, psychology, personality etc.). 2. Because of librarian's unique exposure to human relations and their personal awareness of other people's need, YA librarian should bring a person-centered managerial technique. 3. Librarianship may not have a clinical counseling function but to provide right answer or information, the librarian become counselor inescapably. 4. Librarians are not professionally trained to be experts on counseling in sex education. However, librarians can play an important role in educating YA by committing book selection, reader's advisory, referral services, library programming and staff development planning.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.574-576
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• 2002

인터넷상에서의 정보검색은 검색엔진을 이용하여 이루어지는데, 방대한 사이트들을 검색하여야 하므로 검색효율이나 검색된 정보의 유용성에 문제가 있게 된다. 만약 이러한 정보들을 미리 자동적으로 검색, 분류해서 저장한다면 위의 두 가지 문제들을 해결할 수 있을 것이다. 자동적으로 이런 일을 처리하도록 고안된 것이 웹 로봇 에이전트라고 하며 현재국내에도 여러 개의 웹 로봇 에이전트를 이용한 검색엔진이 사용되고 있다. 본 논문에서는 검색엔진을 구현하기 위해 하이퍼텍스트 전송규약에 대한 연구와 웹 로봇 에이전트에 대한 연구를 하여 올바른 로봇 에이전트를 구현하여, 구현된 검색엔진을 통한 효율적인 정보검색을 실현하는데 목적이 있다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1130_1131
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• 2009

현재까지 국내 PV시장은 신재생에너지 개발 이용 보급 촉진법을 통해서 태양광발전시스템의 이용 보급의 확대를 목표로 하고 있지만 이에 따른 해결해야할 기술적인 문제점들이 많다. 즉, PV시스템의 성능특성 평가분석은 발전성능에 중대한 영향을 미치는 주요 발생손실을 평가.진단함으로서 손실저감을 통한 시스템의 성능개선, 최적절계, 사후운영관리 및 유지점검 등의 응용기술을 개발하는데 있다. 이러한 기술개발을 위해서는 입력인 태양에너지로부터 PV어레이의 직류출력에서 시스템의 교류출력까지의 성능 및 발생손실에 대해서 정량적인 값으로 나타낼 필요가 있다. 본 논문에서는 태양광발전 설비의 효율에 관한 파라미터인 위도와 경도, 온도 및 일사량, 시스템 구성요소에 대한 세부적인 기술검토와 태양광발전시스템의 효율을 개선시킬 수 있는 파라미터에 접근하기 위해 정확한 시스템의 운전특성을 분석 하고자 한다.

• Journal of Korean Library and Information Science Society
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• v.36 no.1
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• pp.309-327
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• 2005

This Study analyzes the present's children library movement. For this, this research deals with 'Library Movement of Miracle' by Citizen Action for Reading Culture. 'Mini-Library Making Movement in Bucheon' and 'Children Mini-Library Movement' by a variety of Nongovernmental organizations. The writer looks into contents, characteristics, meanings and limitations of these Movements. In conclusion, the writer suggests the direction of children library movement in the future.

• Journal of Powder Materials
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• v.6 no.3
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• pp.231-237
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• 1999

In this study, the characteristics of gas atomized Mg-3wt%Al-1wt%Zn-1wt%MM alloy powders under vacuum condition were investigated. In spite of the low fluidity and easy oxidation of the molten magnesium, the spherical powders could be successfully produced by using a modified three pieces nozzle attached to the gas atomization unit. It was found that most of the solidified powders less than 50$\mu$m in diameter were single crystal and the solidified structure showed a typical dendritic morphology due to supercooling prior to nucleation. The secondary dendrite arm spacing decreased as the size of powders decreased. The Mg-Al-Ce intermetallic compounds with chemically stable phase were found in the interdendritic regions of $\alpha$-Mg. It is considered that formation of the chemically stable phase may possibly affect to improve the corrosion resistance. Therefore, it is expected that the materials formed of these Mg-Al-Zn-MM alloy powders shows better mechanical properties and corrosion resistance due to the structural refinement.

• Journal of Korean Library and Information Science Society
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• v.20
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• pp.187-216
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• 1993

The overall goal of this study is to identify what I'||'&'||'R is, and what services should be offered as legitimate I'||'&'||'R actives. The gist of the study is as follows: 1. The shift of the clients targeted to receive the services from disadvantageous to every person. 2. Ambiguity in I'||'&'||'R definition. Because it is hard to distinguish I'||'&'||'R service from the traditional reference service, and shifting of clients, the establishment of the definition was very difficult. Instead of a definite answer, the criteria for "I'||'&'||'R Providers" was drawn. 3. Most provided services were simple and complex information giving based on resource file. Constructing resource file is a major component of I'||'&'||'R service. 4. From 1980s, many I'||'&'||'R providing libraries adapted computer a n.0, pplications. 5. Social work and library-internship was advised to conduct a cooperative project by NCLIS, I'||'&'||'R Task Force. 6. In the high technological era, there continue to be many people who need the su n.0, pportive relationship. I'||'&'||'R is to optimize both the service and clients. Librarian must learn from the principle of high tech/high touch.