• 한국정보통신학회논문지
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• 제22권3호
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• pp.520-526
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• 2018

본 논문에서는 다수의 중계 노드들과 목적지 노드들을 갖는 중첩 전송 기반의 무선 협력 멀티캐스트 통신 시스템을 고려하여, 멀티캐스트 통신의 데이터 전송률을 향상시키기 위한 중계 노드 선택 기법을 제안한다. 또한, 제안하는 중계 노드 선택 기법의 데이터 전송률을 극대화하기 위하여 중첩 전송시 최적의 전력 할당 계수를 이용한다. 중계 노드 선택 기법을 제안하기 위하여 중첩 전송 기반의 무선 협력 멀티캐스트 통신 시스템의 데이터 전송률의 근사식을 유도하고, 그 근사식을 토대로 부분적인 채널 상태 정보만을 이용하는 중계 노드 선택 기법을 제안한다. 또한, 제안하는 중계 노드 선택 기법에 대한 근사적인 평균 데이터 전송률을 유도한다. 수치적 결과에서, 제안하는 중계 노드 선택 기법과 전체 채널 상태 정보를 이용하는 최적의 중계 노드 선택 기법에 대한 평균 데이터 전송률을 비교하여, 높은 신호 대 잡음 전력비의 영역에서 제안하는 중계 노드 선택 기법이 최적의 중계 노드 선택 기법과 매우 유사한 성능을 제공함을 확인한다.

• 전기학회논문지
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• 제56권9호
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• pp.1521-1526
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• 2007

This paper presents the application of Adaptive Evolutionary Algorithm (AEA) to search an optimal setting of overcurrent relay coordination to protect ring distribution systems. The AEA takes the merits of both a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner to use the global search capability of GA and the local search capability of ES. The overcurrent relay settings and coordination requirements are formulated into a set of constraint equations and an objective function is developed to manage the overcurrent relay settings by the Time Coordination Method. The domain of overcurrent relays coordination for the ring-fed distribution systems is a non-linear system with a lot of local optimum points and a highly constrained optimization problem. Thus conventional methods fail in searching for the global optimum. AEA is employed to search for the optimum relay settings with maximum satisfaction of coordination constraints. The simulation results show that the proposed method can optimize the overcurrent relay settings, reduce relay mis-coordinated operations, and find better optimal overcurrent relay settings than the present available methods.

• 전기학회논문지
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• 제62권11호
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• pp.1604-1609
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• 2013

When the ground fault on the power side occurs on distribution system interconnected with distributed generations, the abnormal current is generated in the neutral conductor by the connection type and the iron core structure of transformers for the interconnection of distributed power supplies due to the unbalanced voltage of the system, and subsequently the false operation of the protective relay on the load side occurs. Herein, this paper proposes the method to correct errors in the phase current to prevent the false operation of the protective relay by applying p-q theory and presents the simulation result of the error correction algorithm using PSCAD/EMTDC.

• 한국정보통신학회논문지
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• 제7권4호
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• pp.658-666
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• 2003

본 논문에서는 M/W 디지털 방송중계용 주파수의 공유방안에 관한 연구의 기초단계로서 AWGN 채널 환경에서 M/W 디지털 방송중계용 FPU(Field Pick Up) 무선전송 시스템 규격 및 특성을 분석하고 시뮬레이터 설계를 통하여 시스템 성능을 분석하였다. 국내 방송 중계용의 경우 디지털화 진행이 추진되고 있는바 향후 M/W 방송중계용 주파수 재배치를 위한 간섭평가 및 국내 방송중계용 표준화에 대한 기초 자료로 활용하고자 한다.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.29-35
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• 2008

With long time setting, zone 3 impedance relays are considered insensitive to power swings, and their operation condition during power swings is seldom analyzed. Instead of ti me-consuming simulation to the swing loci, their operation condition is directly quantified by polynominal functions in this paper to find the critical swing angle and frequency for relay operation under different relay settings and system parameters. It is found: (1) the swing loci are more densely populated inside than outside of the protection region, which corresponds to long residence time and possible relay operations; (2) the relays may be sensitive to load encroac hments and stable power swings with different relay settings and system parameters; (3) the critical swing frequency may be in the range of low-frequency power swings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2105-2106
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• 2006

Currently the settlement system which is used at credit card settlement from the member store of the off-line credit card is composed of the credit card settlement terminal, the VAN company which does a settlement relay service and the credit card company. When the obstacle occurs from the credit card company, the VAN company which does a settlement relay service conducts an approval vicarious execution, but when the obstacle occurs from the VAN company, the credit card settlement service is not accomplished smoothly. The dissertation proposes the credit card settlement system which receives a settlement relay service that credit card settlement terminal uses a telegram conversion Agent from other VAN company when the VAN company obstacle occurs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.902-904
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• 1998

When the faults occur in power systems, the protective relay plays a roles of protecting power systems. It is important that the protective relay have high selectiveity and sencitivity performance in power system by correct setting the relays. This paper proposed a testing methods if the reliability of digital relay as simulating the response of relay at faults in the real power system operation environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.161-162
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• 2008

The steady state performance test for the digital protective relay using general relay test equipment has been main test methods. Because of the development of advanced power system testing equipments, dynamic performance test has been carried out additionally using a digital simulator such as RTDS(Real Time Digital Simulator). For the case of newly adopted digital protective relay with IEC 61850 and network, performance testing items need supplementing. This report displays testing items change according to newly protective relay.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.120-123
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• 2005

This paper, for the establishment of power system models and test procedures for the dynamic performance test of transformer protective relay, presents power system model, environment establishement between RTDS and protective relay, and the dynamic performance test generated internal fault or external fault.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.518-524
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• 2002

A software system that has functions of setting and coordination checking of protective relays in power transmission system has been developed. The developed system utilizes database system to store the setting values of protective relays, power system parameters, checks the relay operation and evaluates coordination of relays in real Power system or test system. The fault data to simulates a fault to evaluate the coordination of relays is generated by PSS/E and EMTP. A universal logic generator module is added to adopt the variation of each relay＇s trip logic. The proposed system has been verified through many tests in the case study, and proved to be very powerful in inspecting the setting values and coordination of relays.