• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.191-200
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• 2009

This paper, which consists of two parts, dealt with the parameter tuning of the power system stabilizer for a 612[MVA] thermal power plant in KEPCO system and its validation in field test. In Part 1 of the paper, the selection of parameters such as lead-lag time constants for phase compensation, system gain was optimized by using linear & eigenvalue analyses and they were verified through the time-domain transient stability analysis. In part 2, the performance of PSS was finally verified by the generator's on-line field test. Through the comparisons of simulation results and measured data before and after tuning of the PSS, the models of generator and its controllers including AVR, Governor and PSS used in the simulation are validated and confirmed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1028-1032
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• 1996

Stabilization performance of a sight stabilization system can be improved by proper selection of control algorithm and mechanism. In that aspect, in this paper, effects of an inertia balancer are studied. Parameters of the inertia balancer were obtained from the governing equation by assuming there is no external force and friction. Simulation and experimental results show that the inertia balancer contributes significantly to the stabilization of the line of sight(LOS). In particular, it was found that the inertia balancer is more effective as frequency of the disturbance increases.

• Journal of dental hygiene science
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• v.4 no.2
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• pp.49-53
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• 2004

The purpose of this study is to show dental hygienist's stable and comfortable attire during dental paitients treatment, and to enhance dental hygienist's image. 486 adult patients who visited local dental clinics or centers in three cities of Jeonbuk province, Jeonju, Iksan and Gunsan were surveyed by self developed questionnaire. The collected data were analyzed with frequency, percentage and chi-square test (${\chi}^2$-test), using SPSS program. The results of this study are as follows: 1. Respondents preferred two-piece skirt (39.1%), the face with whole make-up (45.9%). There were significant differences in gender (p<0.01). 2. 36.2% of respondents preferred pink-colored uniforms. 3. Respondents preferred sandal (44.2%), there were significant differences in age, gender (p<0.01, p<0.05). 4. In terms of indication or identification for dental hygienists, 60.7% of respondents preferred nameplate. There were significant differences in age (p<0.05). 5. 75.9% of respondents thought that favorite uniform and costumes that patients prefer could help them feel easy.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.133-135
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• 2007

2003년 8원 북미 북동부지역 광역정전에 이어 영국과 말레시아, 이태리에서도 대규모 정전이 발생하여 지진, 태풍에 버금가는 사회적인 혼란과 경제적인 피해를 초래했다. 이러한 광역 정전사고는 학내 전력산업계에도 상당한 충격과 시사점을 제공했고, 정부와 전력거래소 주도하에 대정전의 원인과 이를 방지하기 위한 권고치에 대한 다각적인 검토와 보완이 이루어지고 있다. 이 보완사항에는 대규모 정전을 막기 위해 필수적인 대규모 발전소 및 변전소에 계통안정화장치의 설치, 통신규격의 표준화, 인격 취득자료의 정확도를 유지하기위한 전력시장운영규칙의 개정 능의 제도적인 지원뿐만 아니라 급전원에 대한 주기적인 교육을 통해 상황대처능력을 향상시키기 위한 노력 등 대정전을 예방하기위해 전력산업 전반에 걸쳐 다양한 개선과 노력이 이루어지고 있다. 이에 대한 노력과 함께 전력거래소는 후비급전소를 천안으로 이설 중에 있고, 공공기관 지방이전 시에 신규로 중앙급전소를 설치 할 예정이다. 본 논문은 위에서 언급한 광역정전을 예방하고, 전력계통을 안전하고 효율적으로 운영하기위한 중앙급전소를 설계할 때 고려해야 할 사항에 대해 논하고자 한다.

• Development and Reproduction
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• v.6 no.2
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• pp.97-104
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• 2002

In most mammals, mature oocyte-cumulus complexer(OCCs) ovulate into the oviduct where fertilization by sperm takes place. However, the complex that fail to fertilize eventually undergoes degeneration while they reside in the oviduct. Yet there is no blown mechanism how both oocyte and cumulus cells degenerate. Using human follicular fluid (hFF), bovine oviductal tissue extract (BOX) and mouse OCC, the present study aimed to find how the oviduct influence the viability of the oocyte and cumulus cells in vitro. There was no difference of oocyte maturation rate between the control and BOX-treated groups. However, there was a significant difference in the survival of cumulus cells between two groups. Cumulus cells cultured in the presence of hFF alone underwent initially expansion and then they formed monolayer in the culture dish. Even after 72 hr, they proliferated well and showed fibroblast-like morphology. Cumulus cells cultured in the presence of both hFF and BOX also expanded after 24 hr, however, after 72 hr culture, they eventually detached and degenerated. Cumulus cells cultured in the BOX alone gave a similar drastic result. When the cumulus cells cultured in the presence of BOX were stained with DAPI, their nuclei showed partial condensation and fragmentation. After detailed analysis of these cells by TUNEL assay, many nuclei of them exhibited well stained spots indicating the signs of apoptosis. Based upon these observations, it is suggested that BOX might possess a factor that leads mouse cumulus cells to undergo apoptosis in vitro.