• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.14-19
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• 2005

A transient numerical simulation was conducted to have variation of temperature on an element of resistive Superconducting Fault Current Limiter (SFCL) under quench condition. It is very important engineering information for an optimum design of cryogenic system for cooling of a resistive SFCL element. A bifilar coil for resistive SFCL for 10 MVA system was incorporated as a model in this numerical study. From the numerical simulation result, it was found that the averaged temperature on the shunt and Bi-2212 element at 500 kW, 100 ms was 711.1 K and 198.4 K respectively. The temperature variation with the change of the hot-spot size and time is also obtained. The maximum temperature was continuously increased in all cases until the hot-spot stops at 100ms and it was going down after then. Such as, the details of temperature distribution on the SFCL element obtained from this numerical study and it should be very valuable information on the decision of the cooling capacity of cryogenic system.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.391-394
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• 2009

In this paper, achieved rise temperature distribution about degradation phenomenon of 2 MVA distribution mold transformer using finite element method (FEM). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage winding and low-voltage winding of mold transformer and Joule's loss of core for improvement these life, forecasted heat source, and high-voltage winding and low-voltage winding of mold transformer and rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the result Also, calculated temperature rise limit of mold transformer and permission maximum temperature using analysis by electron miracle heat source alculate and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• 인포메이션 디스플레이
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• 제6권4호
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• pp.11-21
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• 2005

평판 디스플레이 장치가 LCD-TV에 사용되는 경우 시야각 특성과 동화상 성능은 보다 중요한 성능이 된다. 전반적인 LCD의 화질 특성은 시야각 특성과 동화상 응답 속도를 제외한 모든 부문에서 경쟁 기술보다 우세하다. 이러한 디스플레이의 시야각 특성을 개선하기 위해 LCD업계에서는 IPS, MVA, PVA 등 시야각 특성이 개선된 광시야각 액정 Mode를 개발하여 사용하고 있지만 여전히 LCD는 자발광 디스플레이에 비하여 측면 시인성 측면으로 열세에 있었다. 최근에는 LCD의 측면 시인성을 획기적으로 개선 할 수 있는 기술이 개발되어 더 이상 LCD-TV 응용에서 문제가 되지 않을 수준이 되고 있다. 본 논문에서는 여러가지 광시야각 액정모드 LCD의 측면 시인성 향상 기술에 대한 개략적인 사항을 알아보고, 그 중 Super PVA 액정 기술의 기본원리와 동작 방법에 대하여 상세히 기술하기로 한다.

• 전기저널
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• 통권277호
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• pp.69-77
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• 2000

최근 전력설비 운용상의 여러 가지 과제에 대한 유망한 해결책으로서 파워일렉트로닉스 기기를 사용한 FACTS(Flexible AC Transmission System)가 주목을 받고 있다. 그 중에서도 자려식 변환기를 사용한 FACTS기기는 계통의 유효전력$\cdot$무효전력을 계통의 상태에 의존하지 않고 자유롭게 제어할 수 있어, 계통운용의 유연성을 비약적으로 확대할 수 있는 가능성이 있다. 미쓰비시전기는 전력기기간 계통에서의 자려식 변환기 응용의 파이어니어로서 1991년 간사이전력(주) 태산개폐소에 80Mvar SVG(전지형 무효전력발생장치)를 납품하였으며 또한 자원에너지청의 ''연계강화기술개발'' 보조사업으로 도쿄전력(주)을 비롯하여 전력회사 각사, 전원개발(주)와 (재)전력중앙연구소의 지도 하에 3단자 BTB(Back to Back) 실증시스템용으로 세계 최초의 6인치 GTO(Gate Turn-off Thyristor)를 사용한 53MVA의 자려식 변환기를 제작납품하여 수백MVA 클래스의 자려식변환기 제작기술을 확립하였다. 또한 최근에는 동사가 개발한 신소자 GCT(Gate Commutated Turn-off Thyristor)는 지금까지 대용량 자려식 변환기의 커다란 과제였던 운전손실을 반감할 수 있을 것으로 기대되고 있다. 한편 배전 분야에서는 전압변동, 고조파, 순간전압강하 등의 과제가 증가하고 있어, 미쓰비시전기는 이에 응할 수 있는 파워일렉트로닉스 기기로서 콤팩트 SVG(Static Var Generator), SSTS(Solid-state Transfer Switch), 액티브필너를 다수 납품하여 전력품질문제 해결에 공헌하고 있다.

• 한국유기농업학회지
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• 제27권3호
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• pp.353-363
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• 2019

To identify four cyst nematodes (Heterodera schachtii, H. trifolii, H. glycines, H. sojae) that are economically important plant-parasitic nematodes in Korea, restriction fragment length polymorphism (RFLP) by 8 endonucleases (PstI, VspI, AlwI, RsaI, MvaI, EcoRI, Eco72I, Hinf I) was performed based on sequence difference of mitochondrial DNA cytochrome c oxidase subunit I (COI) gene. As a result, species-specific DNA band patterns by RsaI endonuclease were observed in H. schachtii. The specific patterns was in H. trifolii by 3 endonucleases (VspI, AlwI, Hinf I), and was in H. glycines by Hinf I. While, H. sojae was not digested by 4 endonuclease (VspI, AlwI, RsaI, Hinf I). This study showed that four cyst nematodes could be distinguished using RFLP by 4 endonucleases (RsaI, VspI, AlwI, Hinf I) based on the sequence difference of COI gene.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1710-1712
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• 1996

This paper was practiced insulation failure test forcing to accelerate on frequency of 420 HZ. There was manufactured generator stator windings for 500MVA thermal plants and selected accelerating deterioration voltage of 5.5kV/mm for electrical aging. Moreover, so as to verification of this experiments, we carried out modeling analysis due to finite element method using to ANSYS5.0 program for common package and imitated multi-stress aging for analyzing electrical and mechanical stress distribution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.312-314
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• 1999

한전에서는 1996년 제주-해남간 HVDC 설치에 이어, 1999년 서대구 S/S에 SVC를 설치하였다. 이와 관련하여 본 논문에서는 한전계통에 최초로 설치한 서대구 S/S의 SVC설비운용과 관련하여 SVC의 이론 및 제어기법과 관련된 일반이론을 소개하고, 설치된 SVC의 기기구성방식 및 특성, 제어특성, 기기사양 등에 대해 간략하게 소개하고자 한다. 서대구 SVC는 345kV/13.5kV, 100MVA급으로서 TCR 및 TSC방식의 하이브리드 방식으로 되어 있다.

• 전기학회논문지P
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• 제65권2호
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• pp.122-129
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• 2016

Current differential protection relaying with second harmonic restraint is the main protection for large capacity power transformer. PSCAD simulation program is widely used for modeling of dynamic varying transients phenomena. This paper deals with a power transformer model and transients analysis using PSCAD software to develop IED for power transformer. Simulation was carried out using a three phase 40MVA, 154/22.9kV, 60Hz, two-winding transformer with Y-Y connection used in actual fields. The paper analyzed transformer magnetizing inrush, external fault, and internal fault conditions with this model in the time domain. In addition, we performed an analysis in the frequency domain using FFT during several conditions.

• 전기학회논문지
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• 제56권2호
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• pp.295-300
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• 2007

High temperature superconducting (HTS) windings for an HTS transformer which have been developed have two kinds of type, one is the layer winding and the other is disk winding. The layer winding has adopted for an HTS power transformer so far because of the small AC losses of the HTS windings. The disk windings have surface of the HTS wire. We propose a new winding method for a high voltage HTS transformer which has advantages of both type of HTS windings, and we call it continuous disk winding. This new HTS winding consists of pile of HTS disk windings. The continuous disk winding was fabricated with multi-stacked HTS wires for dover HTS transformer. We can check the potential possibility from the characteristic test of the fabricated winding. The new type HTS windings can be applied to HTS power transformers, especially to the high voltage ones.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.156-162
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• 2013

This paper measures the hot spot temperatures in a single-phase, 154 kV, 15/20 MVA power transformer filled with natural ester fluid using optical fiber sensors and compares them with those calculated by conventional heat run tests. A total of 14 optical fiber sensors were installed on the high-voltage and low-voltage windings to measure the hot spot temperatures. In addition, three thermocouples were installed in the transformer to measure the temperature distribution during the heat run tests. In the low-voltage winding, the hot spot temperature was $108.4^{\circ}C$, calculated by the conventional heat run test. However, the hot spot temperature measured using the optical fiber sensor was $129.4^{\circ}C$ between turns 2 and 3 on the upper side of the low-voltage winding. Therefore, the hot spot temperature of the low-voltage winding measured using the optical fiber sensor was $21.0^{\circ}C$ higher than that calculated by the conventional heat run test.