• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.515-518
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• 2002

In this study, the ellipsoidal cap type magnetic pole structure was proposed for the electro-magnet in B-H curve tracer. From the simulation for the electro-magnet without specimen, the area of effective uniform field(99% range for the central field value) was considerably increased in case of the newly proposed ellipsoidal cap type magnetic pole than that of the conventional simple-inclined cap type magnetic pole. Also, through the simulation for the electro-magnet with permanent magnet specimen(NaFe30), the optimal Positions of the magnetic field measurement sensor(Hall sensor) were found out in each case and the errors were decreased in case of the newly proposed ellipsoidal cap type magnetic pole.

• Electrical & Electronic Materials
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• v.4 no.2
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• pp.114-122
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• 1991

본 논문에서는 최근의 고온초전도체 재료의 개발에 주목하여 액체 질소의 절연파괴특성에 전극이 미치는 영향에 관하여 연구하였다. 액체 질소의 극성효ㅗ가는 액체 헤리움과는 달리 전극간 거리에 따라 다르며 단 간격에서의 파괴정압은 평등전계가 가장 높고, 정침, 부침의 순서이며 장 간격에서는 역전한다. 그리고 conditioning효과, 불순물효과, 피복효과, 압력의존성 등의 실험으로 부터 액체 질소의 파괴기구는 정침에서는 정 스트리머, 부침에서는 기포파괴의 가능성이 높은 것으로 생각된다. 또한 극저온 절연 설계에서는 전극을 절연물로 피복하고 고순도 액체 질소보다는 불순물이 혼입된 액체 질소, 즉 상용 액체 질소를 냉각 및 절연재료로 사용하면 유리하다.

• Journal of The Korean Association For Science Education
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• v.20 no.2
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• pp.193-199
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• 2000

The textbook is a predominant feature of most classrooms. Because the textbook is an important aspect of educational experience, it is essential that the content of the texts be carefully scrutinized. The purpose of this study was to examine the visual portrayal of gender groups in elementary $"Chay{\tilde{o}}n"$ textbooks developed by the 6th National Science Curriculum. An instrument was developed to analyze the nature and type of activity engaged in by these groups as well as how often members of these groups were portrayed. Data were collected from 8 elementary $"Chay{\tilde{o}}n"$ textbooks. The results show the following two different features. While the elementary $"Chay{\tilde{o}}n"$ textbooks do not show gender-biases in representing science learning activities such as observing, experimenting, measuring, they show distinct gender-stereotyped roles and activities. It is expected that the results of this study are considered in developing the new elementary "Science" textbooks which show gender-fairness.

• Journal of the Korean Society for Library and Information Science
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• v.36 no.4
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• pp.157-173
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• 2002

To bridge digital divide, the nation's information services should be focused their attentions on people with disabilities. According to this philosophy, the public library's services for people with disabilities should be main streamed into its regular services. Providing equitable access for people with disabilities to public library's resources, facilities, and services, the standard library services policy or guideline should be developed as soon as possible. A draft in this papers may be helpful to a policy maker for public library services for people with disabilities

• Journal of the Korean Society for Library and Information Science
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• v.36 no.3
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• pp.233-258
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• 2002

The aim of this research is to investigate the history of the public library movement and identify the achievements and limitation, finally looking for the significance and direction of the public library in the future. This research proves through the history of the public library movement that in the information era the public library can be one alternative in realizing the publicity and equality of knowledge and information of our society.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.181-183
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• 2002

컴퓨터와 인터넷의 발달로 과거에는 서적이나 신문과 같은 종이를 통하여 공급되던 정보들이 전자문서로 바뀌고 있고, 전자문서에서는 색상 정보를 동반한 그래픽과 영상 정보의 비중이 크게 높아지고 있다. 그러나 색상 인식 기능이 없거나 손상된 색각 장애자의 경우 전자 문서에서 색상으로 전달하는 중요한 정보를 인지하지 못하여 정보 취득의 평등권이 침해당하고 있다. 본 연구에서는 윈도우즈를 운영체계로 하는 컴퓨터에서 적록 색맹 및 색약을 가진 색각 장애자를 위하여 전자 문서상에서 제공되는 색상을 변환하여 보정하는 색각 보정 시스템을 설계하고 구현하여 그 타당성을 입증하였다. 개발된 시스템은 여러 문서를 동시에 사용할 때에도 적용된 보정 색상이 유지된다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.3
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• pp.106-111
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• 1984

Prebreakdown current pulses arising from avalanche growth in SF6 were recorded under static uniform field at pressures up to about 400kpa. At pressures less than 100kpa the current pulses consist of the electron component observed as the fast rise of current, the negative ioncomponent which is superimposed, and the positive ion component comprising the tail of the pulse. The values of positive ion drift velocity were measured from the present pulse data. At pressures in excess of about 100 Kpa the pulse shapes becam distorted such that quantitative analysis was no longer possible, and did not indicate the action of any photosecondary process at the cathode. Breakdown appers to result from the seperate development of single avalanche.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2299-2301
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• 1999

In this work, experimental investigation was carried out for the breakdown characteristics of $SF_6$, $N_2$ and their mixtures under the uniform and non-uniform electric field, by use of HVAC and standard impulse testing voltages, as a function of different gas pressures from 1 atm to 5 atm. The results show that the dielectric strength of the $SF_6$ mixed in $N_2$ was significantly increased at its portion of 10%, which might imply that the optimum mixture of $SF_6$ for the HV switch gear could be proposed to be 10%.

• Journal of Institute of Control, Robotics and Systems
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• v.1 no.1
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• pp.1-3
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• 1995

결합된 시변 상미분 방정식의 해외 점근적 성질에 관한 연구이다. 리아프노프 직접 방법에 의하면 평등 안정성(uniform stability)만 얻어졌을 경우이지만, 추가적으로 상태 벡터 중 일부가 0으로 점근적 수렴함을 보이는데 있다. 얻어진 결과는 특히 불변원리(invariance principle)가 성립하지 않는 시변 시스템에 유용하다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.261-264
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• 2008

In this paper the experiments of breakdown characteristics $SF_6$ liquid ($LSF_6$) in model GIS(Gas Insulated Switchgear) were described. From the experiments results, The ability of $LSF_6$ insulation is higher than high-pressurized $SF_6$ gas. The breakdown characteristics of $LSF_6$ were produced by bubble formed evaporation of $LSF_6$ and bubble caused by high electric emission. It is considered in this paper that the results are fundamental data for electric insulation design of superconductor and cryogenic equipments machinery which will be studied and developed in the future.