• 대한전기학회논문지:전력기술부문A
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• 제53권4호
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• pp.221-226
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권4호
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• pp.221-221
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1864-1872
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• 2014

Maloperation of protective relays is one of the major causes for cascading tripping in WANS. Another line trip followed by a previous line trip may occur due to overloading of the line, because of the load redistribution or unwanted trip of a backup relay due to change in the flow of fault current. Evaluation of each line is required by considering both of these effects. A new index named Line Security Index (LSI) is proposed in this paper which combines both Vulnerability Index (VI) and Protectability Index (PI) to completely evaluate the security of individual lines and their importance in the power grid. Computer simulations have been performed on the Korean power grid data to establish the feasibility of the proposed idea.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.544-549
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• 1995

An analysis for Steam Line Break (SLB) events which result in a return-to-power conditions after reactor trip was performed for a postulated Yonggwang Nuclear Power Plant Unit 3 cycle 8. Analysis methodology for post-trip return-to-power SLB is quite different from that of a no return-to-power SLB and is more complicated. Therefore, it is necessary to develop an methodology to analyze the response of the NSSS parameter and the fuel performance for the post-trip return-to-power SLB events. In this analysis, the cases with and without offsite power were simulated by crediting 3-D reactivity feedback effect due to local heatup around stuck CEA and compared with the cases without 3-D reactivity feedback with respect to fuel performance, departure from nucleate boiling ratio (DNBR) and linear heat generation rate (LHGR).

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1046-1052
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• 2017

The load on the power grid of South Korea is expected to grow continuously until the late 2020s, and it is necessary to increase the transfer capacity from the Eastern grid to the Seoul-Gyeonggi region by reinforcing the transmission network for the electric power system to remain stable. To this end, the grid reinforcement by two bipole LCC HVDC transmission systems have been considered on account of the public acceptability and high growth of the fault current level, even though an additional 765kV system construction is more economical. Since the probability of the existing 765kV double circuit transmission line trip is extremely low, a dynamic simulation study was carried out to estimate the efficient HVDC capacity able to stabilize the transient stability by utilizing the HVDC overload capability. This paper suggests the application plan to reduce the HVDC construction capacity with ensuring the transient stability during the 765kV line trip.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.335-336
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• 2008

Overhead transmission lines are mainly crossing mountainous area. They are easily affected in weathers like typhoon, strong wind, lightning, heavy rain, or heavy snow. Sometimes these weathers cause transmission line faults. A lightning flashover is most often fault. Nowadays lightning density in KOREA is growing high and lightning flashovers occur more often. A lightning flashover on transmission line is mostly cleared by momentary operation of a circuit breaker, so power failure happens rarely. However, when both circuits trip simultaneously due to the lightning flashovers on double circuit transmission line, short time power failure and voltage drop happen. KEPCO has used transmission line arresters to avoid double circuit simultaneous trip out since 2003. And transmission line arresters cannot be installed with KEPCO's present metal fittings, so various fittings have been used for each transmission line arrester manufacturer. This paper introduces development and standardization of arc-horn and metal fittings for transmission line arrester which can be used for both existing lines and new lines in KEPCO.

• Molecules and Cells
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• 제43권3호
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• pp.236-250
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• 2020

Currently, many available anti-cancer therapies are targeting apoptosis. However, many cancer cells have acquired resistance to apoptosis. To overcome this problem, simultaneous induction of other types of programmed cell death in addition to apoptosis of cancer cells might be an attractive strategy. For this purpose, we initially investigated the inhibitory role of TRIP-Br1/XIAP in necroptosis, a regulated form of necrosis, under nutrient/serum starvation. Our data showed that necroptosis was significantly induced in all tested 9 different types of cancer cell lines in response to prolonged serum starvation. Among them, necroptosis was induced at a relatively lower level in MCF-7 breast cancer line that was highly resistant to apoptosis than that in other cancer cell lines. Interestingly, TRIP-Br1 oncogenic protein level was found to be very high in this cell line. Up-regulated TRIP-Br1 suppressed necroptosis by repressing reactive oxygen species generation. Such suppression of necroptosis was greatly enhanced by XIAP, a potent inhibitor of apoptosis. Our data also showed that TRIP-Br1 increased XIAP phosphorylation at serine87, an active form of XIAP. Our mitochondrial fractionation data revealed that TRIP-Br1 protein level was greatly increased in the mitochondria upon serum starvation. It suppressed the export of CypD, a vital regulator in mitochondria-mediated necroptosis, from mitochondria to cytosol. TRIP-Br1 also suppressed shikonin-mediated necroptosis, but not TNF-α-mediated necroptosis, implying possible presence of another signaling pathway in necroptosis. Taken together, our results suggest that TRIP-Br1/XIAP can function as onco-proteins by suppressing necroptosis of cancer cells under nutrient/serum starvation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.132-135
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• 2001

To improve the fault coordination of underground distribution line we study the several contents such as the magnitude of fault current in distribution line tripping time of CB by acting of over current relay with instantaneous trip and time delay trip. We also examine the melting time of current limiting fuse inside power fuse Through the research as above. we suggest the modification scheme of fault coordination to reduce the interruption times of power failure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.60-61
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• 2006

An unwanted trip of backup distance relays often lead to a blackout. This paper presents investigation report on involvement of backup distance relays in the past blackouts and sensitivity-factor based algorithm to make a distinction between a fault and overload caused by line tripping. A preliminary idea to prevent deterioration of the situation due to unwanted trip of distance relays by utilizing the proposed algorithm is presented.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.458-461
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• 2009

3상 4선식 배전방식에서 비선형 부하증가로 인한 제 3고조파 전류발생은 선로의 중성선 및 기기를 과열시키는 원인으로 작용하고 있다. 따라서 고조파에 의한 역률저하 및 기기, 선로 등을 안전하게 보호할 필요가 있다. 본 논문에서는 제 3고조파 전류로 인한 사고사례를 조사하고 고조파 분석 및 부하 불평형 등을 분석하였다. 이를 통해 가장 경제적인 4극 저압차단기를 사용하여 중성선의 과전류로부터 선로 및 기기를 보호하는 방법을 제시하였다.