• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.140-150
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• 2008

Point Coordination Function (PCF) of the IEEE 802.11 protocol providing a centrally-controlled polling-based multiple access to a wireless channel is very efficient in high load conditions. However, its performance degrades with increasing the number of terminals and decreasing the load, because of wastes related to unsuccessful polling attempts. To solve the problem, we propose and study analytically the generic dynamic polling policy using backoff concept. For this aim, we develop Markov models describing the network queues changes, what allows us to estimate such performance measures as the average MAC service time and the average MAC sojourn time, to show the dynamic polling efficiency and to tune optimally the backoff rule.

• Journal of Korean Neurosurgical Society
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• v.39 no.1
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• pp.58-60
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• 2006

Hypothalamic hamartoma[HH] is an unusual nonneoplastic developmental lesion associated with gelastic epilepsy and precocious puberty, mostly found in children. Although open surgery has been attempted when antiepileptic medication failed to control seizures, its deep location and surrounding vital structures often rendered surgery unsuccessful. We describe the outcome of gamma knife radiosurgery in three children with a HH associated with gelastic epilepsy and reviewed the literature for a possible therapeutic mechanism.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2061-2062
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• 2011

국내 원자력발전소에 설치되어 있는 고압케이블은 장기운전에 따라 열화진단 및 유지보수의 필요성이 증대되고 있다. 주기적 안전성 평가(Periodic Safety Review) 및 계속운전과 관련하여서도 고압케이블의 관리방안이 지속적으로 요구되고 있다. 본 논문에서는 원자력발전소에 설치되어 있는 13.8kV급 고압케이블의 건전성을 확인하기 위하여 원자력발전소 계획예방정비 중 열화진단을 수행한 결과를 소개하고 있다. 특히 미국 NRC(Nuclear Regulatory Commission)에서는 케이블 진단 기법 11가지를 권고하고 있는데 본 논문에서는 그 중 국내 원자력발전소에 적용이 가능한 최신 케이블 진단 기술인 HFCT(High Frequency Current Transformer)를 이용한 부분방전(Partial Discharge ; PD) 측정, VLF(Very Low Frequency) 장치를 이용한 $Tan{\delta}$ 측정 및 열화상카메라를 이용한 케이블 온도 측정을 사용하여 고압 케이블 진단을 실시하였고, 그 결과를 서술하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.517-518
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• 2011

본 논문에서는 국내 원자력 발전소용 고압케이블의 열화평가를 위해 열적, 화학적 시험을 진행하였다. 최근 설계수명이 종료되는 원자력 발전소와 케이블들에 대한 열화평가 연구가 시작되고 있다. 그러나 현재까지 기초연구 수준에 머물러 있기 때문에 체계적인 열화평가 이루어지고 있지 않다. 따라서 본 논문에서는 국내 원전 고압케이블의 열적, 화학적 시험을 통해 기초 물성자료를 구축하고 열화평가에 이용하기 위해 본 시험을 수행하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2067-2068
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• 2011

국내 원자력발전소에 설치되어 있는 고압케이블은 장기 운전에 따라 열화진단 및 유지보수의 필요성이 증대되고 있으며, 주기적 안전성 평가(Periodic Safety Review) 및 계속운전과 관련하여서도 고압케이블의 관리방안이 지속적으로 요구되고 있다. 본 논문에서는 원자력발전소에서 경년열화로 진단되어 철거된 케이블을 수거하여 VLF(Very Low Frequency) 장비를 사용하여 가압을 한 후 HFCT(High Frequency Current Transformer)를 이용한 부분방전(Partial Discharge ; PD) 측정을 수행하여 향후 원자력발전소 계획예방정비 시 케이블을 대상으로 Off-line 부분 방전 진단이 가능한지를 검토하였고, 그 결과를 기술하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2011_2012
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• 2009

내환경검증은 원자력발전소 안전성 관련 계통의 기기가 정상운전 및 설계기준 사고 환경에서 안전기능을 수행할 수 있는지를 검증하는 것이다. 기기검증 평가에 관한 사항은 원자력법시행규칙 '제19조의2(주기적안전성평가의 세부내용)에 따르며 세부평가 대상범위는 안전기능을 확보하기 위한 안전관련 전기기기, 기능이 상실되면 안전관련 기능 수행을 저해하는 비 안전관련 기기, 규제지침 Reg Guide 1.97에서 요구하는 사고 후 감시기기 등이며 국내의 경우에는 경수로형 원전 안전심사지침 제3.11에 따른 내환경검증 기계류 기기의 비금속 부품 등이 추가로 해당된다.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.05a
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• pp.183-188
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• 2006

In general, performing facilities consist of various functional groupings. The functional groupings should be arranged, in relation to each other, depending on the circulation of users in a space. The performing culture in Korea has been rapidly progressed in recent years. However, compared to the superior examples of foreign performing facilities, it still needs improvements and systematic research. In this study, the functional groupings of general performing facilities as well as the circulation patterns of users will be analyzed. From the results of this study, a circulation system for each spatial composition will be suggested for the performing facilities to be constructed in the future.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2004.05a
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• pp.86-90
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• 2004

The whole image of circulation occupied with user has duplicated inter-relationship. It means many situation exist simultaneously, and the character of space factors are completed by the inter-relationship of the detailed structure. The purpose of this study is on the proper notation for circulation analysis of the sequential space structure which is constructed by the formal constituent and the change of visual circumstance influence on the action of user. This study investigate the possibility of notation by arranging the analysis method of the visual space and focusing on the research for the visual perception behaviour of user being applied various space, and the possibility of application as a method of space design.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2004.05a
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• pp.176-179
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• 2004

Space is comprised by the movements of human beings, and draws a complex locus within it. That form seems to be complex of movement around in all directions of space axis, and be ever-changing process as time goes by. Although Human are able to move uninhibitedly, the movements are restricted to a narrow sphere during locomotion. However, the pattern of these movements delineates a certain frame within the space, and provides not only visual effects but also relevance tomovement itself. Also, critically dividing and organizing this sphere is what is realized into this tangible indoor space. This study recognized importance of human being as a core of making indoor space and brought out experimental approach on relationship human with space, and visually perceptual standpoint. And this presented the recent possibility of action and attitude though sight and walking by arranging space on the basis of modern artists' perception of human body.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2004.05a
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• pp.131-135
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• 2004

The purpose of this research is to improve exhibition effectiveness by implementing hands-on exhibition technique that best provides adults with cultural resting place and children with outdoor education which simply supports school curriculum. By completing this research, the museum of natural history will become defined innovatively as a place that enables people actively develop creativity. Seodaemun museum of natural history was selected for this research and itinerary tracking method of Robinson and Melton was adopted to find out adults' and children's particular movements in the museum. At the same time, observation method was used to get information on each room's visiting and viewing rate. In order to understand adults' and children's movements, their behavior was encoded.