• The Journal of the Korea institute of electronic communication sciences
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• 제19권2호
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• pp.361-370
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• 2024

In this paper, a method was studied for applying a series resonant type fault current limiter that can be manufactured at low cost to the smart grid distribution system. First, the impact of the harmonic components of the short-circuit fault current injected into the series resonance circuit of the fault current limiter on the peak value of the transient response was analyzed, and a methodology for determining the steady-state response was studied using percent impedance-based fault current computation method. Next, the effectiveness of the method was verified by applying it to a test distribution line. The test distribution system using the designed current limiter was modeled using EMTP_RV, and a three-phase short-circuit fault was simulated. In the fault simulation results, it was confirmed that the steady-state response of the fault current accurately followed the design target value after applying the fault current limiter. In addition, by comparing the fault current waveform before and after applying the fault current limiter, it was confirmed that the fault current was greatly suppressed, confirming the effect of applying the series resonance type current limiter to the distribution system.

• Food Science and Preservation
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• 제18권2호
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• pp.178-183
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• 2011

The consumer awareness concerning coffee beverages has increased in Korea. The objective of this study was to optimize the roasting conditions of coffee bean for consumer's attribute. The optimal roasting conditions for Colombian coffee beans were analyzed by using a central composite design with a quadratic polynomial model by response surface methodology (RSM). The experimental conditions for coffee bean roasting were $194.82^{\circ}C{\sim}250.00^{\circ}C$ and 7.93~22.07 minutes. The responses of sensory attributes. physicochemical and physical properties were analyzed with RSM. The width. length and height of green beans increased when the beans were roasted. The higher degree of roasting gave the higher pH and solid contents but the lower total acidity and total phenolic compounds. In sensory tests, the roasting temperature and time had a significant effect on the flavor score. The optimum roasting condition of Colombian coffee bean predicted for maximizing the length, width, solid contents, total phenolic compounds and flavor score were 20 minutes at $225^{\circ}C$ by RSM.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.505-508
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• 2016

In city, tracing of power transmission lines is difficult due to compound installation of overhead and underground lines, transposition, bad view caused by trees or big buildings. It is hard problem for electrical technician on site to trace power transformers or power lines to serve customers in 3 phase -4 wires power distribution systems. It is necessary that the correct and fast tracing method is required for load balancing among distribution lines. Old technology use to trace lines with high power impulse injection. Our proposed method uses to trace lines with very small power high frequency signal injection. Simulation models for 3-phase power transformers, 3-phase wire lines, and customer loads are described to investigate the transmission characteristics of high frequency power line carrier. Distribution lines have only a limited ability to carry higher frequencies. Typically power transformers in the distribution system prevent propagating the higher frequency carrier signal. The proposed method uses the limited propagation ability to identify the power transformer to serve customers. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building. Also some simulations are done to help and understand the concepts by using MATLAB Simulink simulator.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제10권8호
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• pp.1802-1809
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• 2009

Abstract The typical distribution systems have the power flow from distribution substations (sources) to customers (load) only as one direction. However, in the case where distributed generations (DG) such as PV system and wind power systems are connected to distribution systems, the DG output variations to distribution systems, so called reverse power flow, may cause the bi-directional power flow. So, the reverse power flow has severe impacts on typical power system, for example power quality problems, protection coordination problems, and so on. Especially, protection devices (sectionalizer) in primary feeder of distribution system interconnected with distributed generations may cause problems of malfunction, and then many customers could have problems like an interruption. So, this paper presents the bi-directional operation algorithm of protection devices to overcome the problems like mal-function. And, also this paper shows the effectiveness of proposed method by using both PSCAD/EMTDC software and test facility of protection devices to simulate the field distribution systems.

• 전기의세계
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• 제42권2호
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• pp.23-28
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• 1993

작업안전 대책으로서는 기본적으로 인간존중을 바탕으로 안전관리를 추진해 나아가는 것이 가장 좋은 대책이지만 하루에 여러개소의 현장을 이동하고, 각 작업 현장의 형태가 달라질 수 있는 특별한 분야에 있어서는 매우 어려운 요소를 포함하고 있다. 따라서 조금이라도 이에 근접되도록 관계자는 연구와 노력을 계속하여야 하며, 배전작업용 로봇등을 적용하는 특수한 분야에서는 종합적이고 과학적인 방법을 도입하여 작업현장 안전대책을 수립하고 문제점을 적출하여 안전재해 예방에 최선을 다해야 할 것이다.

• 전기의세계
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• 제42권4호
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• pp.53-62
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• 1993

지중배전설비는 신도시 개발, 도심 고층빌딩의 활발한 신증축, 아파트단지 건설의 활기 등으로 계속 증가될 것으로 전망되며, 아울러 경제성장과 국민생활 향상에 따라 고품질 전력 요구는 필연적이며, 또한 지중화 요구도 증대되리라 본다. 지중설비 증가와 아울러 지중케이블 고장은 설비 특성상 장시간 광역정전의 우려가 있는 점을 감안하여 고품질 전력케이블의 기술개발에 끊임없는 연구가 있어야 할 것으로 본다.

• 전기의세계
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• 제15권4호
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• pp.27-38
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• 1966

본 고에서는 앞으로 신설된 배전계통에서의 고저압혼독시 전위상승에 대해 알아보고자 한다. A항의 검토에서 고목계통의 실측치와 D.C. board에 의한 계산치 사이에 약 10-20%의 오차는 있으나 계산치로써 전위상승을 추정할 수 있음을 알았음으로 신설될 23kv Y및 11.4kv Y배전방식에 대하여 계산한다.

• 전기의세계
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• 제20권6호
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• pp.22-28
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• 1971

3상 4선식 다중접지배전선로에서 고저압혼촉이나 1선지락이 발생하면 인근 통신선로에 전자유도전압이 유기되는데 이 유도전압의 정확한 예측은 전자유도장해의 방지책을 강구하는데 있어서 매우 중요하다. 따라서 본 논문은 이 유도전압을 계산하는 이론식을 제시하는데 그 목적이 있다.

• JOURNAL OF ELECTRICAL WORLD
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• 통권349호
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• pp.68-70
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• 2006

배전계통에서선로의전압강하보상및 역율개선에의한설비용량증가문제는쉬운듯 하지만실제문제풀이에서는정답을내는확률이의외로낮다. 문제출제의도에따라서문제는다른듯 하지만접근하는기본원리식은같다. 즉, 설비가가지고있는설비용량[ k v a ]는 변함이없는데단지역율이변동됨에따라서유효전력[ k w ]이 설비용량을반경으로하는범위로변동된다는것이다.

• Proceedings of the KIEE Conference
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.483-484
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• 2015