• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.7
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• pp.14-21
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• 2015

Distribution systems are operated in radial structure, but temporal loop structure could be founded the live load transfer. Main purposes of reconfiguration of distribution network are load balancing, loss minimization and voltage drop maintaining. In the loop structure, huge loop current can be flowed between two substations in case of large voltage angle difference. Protection devices of distribution line can be triped by this huge loop current. So, precise calculation of loop current is very important for secure switching. This paper proposes a novel calculation method of loop current using the voltage angle differences measured at the tie switches. Feasibility of the propose method has been verified by various case studies based on Matlab simulation.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.182-184
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• 2000

There are several facilities in Kochang distribution test center such as artificial fault generator(AFG), new distribution automation system(NDAS), communication networks (wireless and optic), lumped constant circuit, switches for distribution automation, overhead and underground distribution line. We have been field testing on remote control, data acquisition. remote metering, feeder automation and so on for distribution automation using those equipment.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.152-154
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• 2005

This paper proposes new methods which are used for trouble detecting and tolerance of IED in IEC61850 based Substation Automation System. There are three point devices for construction of this system: Trouble Detection IED, Backup IED and Engineering Unit. Trouble Detection IED tests trouble of Bay IED and sends the result to Engineering Unit. And then Engineering Unit is able to control the system. When fault occurs in Bay IED, Backup IED will be substitute the troubled Bay IED. If this proposed scheme can be used in this system, the reliability of the Power System would be greatly improved.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.70-72
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• 2005

변전소 내 IED의 신뢰도는 전력계통 운용과 보호에 매우 중요한 주제가 되었다. 또한, 서로 다른 회사에서 제작된 다른 기술을 이용한 IED들을 사용할 경우 신뢰도 유지에 힘든 것이 사실이다. 이를 해결하기 위하여 변전소 자동화의 구조 및 충신을 정의한 IEC61850이 제안되었다. 본 논문에서는 IEC61850기반의 변전소 자동화 시스템을 위한 새로운 신뢰도 향상 기법에 대해 제안한다 제안하는 방법은 패턴 검사를 통해 IED의 고장을 검출하고, 백업 IED와 소프트웨어 이동을 이용하여 결함을 극복하는 것이다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1010-1016
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• 1999

Protease related mold was isolated and selected as a starter culture for commercial production of meju. Isolated microorganism was identified as Syncephalastrum racemosum PDA 132 2. To obtain basic data about protease for production of soybean peptides and application of the strain in meju fermentation, we extrated and purified protease and charateristics of the enzyme were investigated. The optimum condition for the production of enzyme was pH 4.0, 30oC, 5 days. The protease was purified 19.7 folds by gel filtration and ion exchange chromatography and specific activity was 12.4unit/mg. The purified enzyme was 34kDa in size, thiol protease(100% inhibited by PCMB), and was acidic protease(stable between pH 2.0~5.0). Vmax of the enzyme was 2.14 g/min which was lower(1/50) than that of by Asp. wentti and B. subtilis.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.550-555
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• 2004

Fault section isolation and service restoration are very important for function of DAS. In Japan, a progressive protection method is used for the line to ground fault section isolation and service restoration. But the progressive protection method has a drawback that the customer will experience outage time and that the rate in use of the feeder is not over 50%. This paper presents a new Service Restoration Algorithm which is for the line to ground fault section isolation and service restoration method for a ungrounded distribution system. If the proposed algorithm is used, the rate in use of the feeder can improve than before because a distribution system can change multi connection of feeder and the customer's outage time can be reduced. The proposed algorithm has been successfully tested in a distribution system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.581-588
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• 2004

Power qualify monitoring system is devoted to more concern than before, because the innovation of industrial technology needs more accurate instruments and more advanced power quality. This paper was studied on using data of the protective relay by Power Quality Monitor. This paper was proposed the wave storage condition and monitoring clauses of the protective relay as a power quality monitoring device. The protective relay will have problem to save data for PQM analysis because the protective relay memory is limited. Therefore this paper was proposed new a data compression of data got from the protective relay. This method is wave compression comparison algorithm using the DFT. The compression rate is higher than any other established method. This method can be real time storage. This algorithm is verified using the comparison among other compression rate and proved by Real Time Digital Simulator (RTDS).

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.129-131
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• 2001

In order to improve the reliability of power service and the effective management of distribution power system. DAS (Distribution Automation system) is widely used in KEPCO(Korea Electric Power Corporation) branch offices. Based on the present protective device coordination program which used in KEPCO. this study presents the new concept about both protective device coordination program maximizing the characteristics of DAS and development plan of protective device auto-coordination program with the merits of DAS.

• Proceedings of the KIEE Conference
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• 2001.05a
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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.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.73-75
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• 2000

The new distribution automation system was developed in KEPCO just recently. This system has many functions for remote control and data acquisition but it has not all functions for the full automated distribution system. This paper presents the contents of many kinds of additional application programs on the stage of developing and coming to the final completion for the large scaled distribution automation system.