• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.556-564
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• 2004

This paper presents an application of parallel Genetic Algorithm-Tabu Search(GA-TS) algorithm to search an optimal solution of a reconfiguration in distribution system. The aim of the reconfiguration of distribution systems is to determine switch position to be opened for loss minimization in the radial distribution systems, which is a discrete optimization problem. This problem has many constraints and very difficult to solve the optimal switch position because it has many local minima. This paper develops parallel GA-TS algorithm for reconfiguration of distribution systems. In parallel GA-TS, GA operators are executed for each processor. To prevent solution of low fitness from appearing in the next generation, strings below the average fitness are saved in the tabu list. If best fitness of the GA is not changed for several generations, TS operators are executed for the upper 10% of the population to enhance the local searching capabilities. With migration operation, best string of each node is transferred to the neighboring node aster predetermined iterations are executed. For parallel computing, we developed a PC-cluster system consisting of 8 PCs. Each PC employs the 2 GHz Pentium Ⅳ CPU and is connected with others through ethernet switch based fast ethernet. To show the usefulness of the proposed method, developed algorithm has been tested and compared on a distribution systems in the reference paper. From the simulation results, we can find that the proposed algorithm is efficient and robust for the reconfiguration of distribution system in terms of the solution qualify. speedup. efficiency and computation time.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.129-134
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• 2011

The construction method in electrical room with hydro power generation is well informed in drawings and according to this method, to master the actual working conditions. It's necessary to consult location of KEPCO liability threshold with the KEPCO side, therefore make a decision to install the underground cable in hydro power station in each state, including outdoor pipes and manholes. Undulating rigid polyethylene conduit (125C) and CNCV-W extra high cable are laid and installed, to make a closely analysis to the construction by reviewing its process. In this work, the key part of the KEPCO power system for House of Commons is actually based on liability threshold, even including outdoors pipeline construction, high voltage underground electrical wiring and switchgear installation. It directly reveals the contents of the proposed construction methods about Housing Corporation and the High Voltage Switchgear Installation Inlet.

• Fire Science and Engineering
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• v.20 no.1 s.61
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• pp.71-76
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• 2006

The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The occurrence factor of the fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Device(RCD) of high sensitivity type used at low voltage wiring cuts off earth leakage and overload, but the RCD can't cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied low voltage distribution panel are prescribed to rated breaking time about 30[ms](KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To be improved on such problem, this paper is proposed to a auxiliary control apparatus for RCD trip on electric arc or spark due to electrical fire. Some experimental results of the proposed apparatus is confirmed to the validity of the analytical results.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.419-424
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• 2012

This paper discusses the state-of-the-art techniques in real-time state estimation for the Smart Microgrids. The most popular method used in traditional power system state estimation is a Weighted Least Square(WLS) algorithm which is based on Maximum Likelihood(ML) estimation under the assumption of static system state being a set of deterministic variables. In this paper, we present a survey of dynamic state estimation techniques for Smart Microgrids based on Belief Propagation (BP) when the system state is a set of stochastic variables. The measurements are often too sparse to fulfill the system observability in the distribution network of microgrids. The BP algorithm calculates posterior distributions of the state variables for real-time sparse measurements. Smart Microgrids are modeled as a factor graph suitable for characterizing the linear correlations among the state variables. The state estimator performs the BP algorithm on the factor graph based the stochastic model. The factor graph model can integrate new models for solar and wind correlation. It provides the Smart Microgrids with a way of integrating the distributed renewable energy generation. Our study on Smart Microgrid state estimation can be extended to the estimation of unbalanced three phase distribution systems as well as the optimal placement of smart meters.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2007.11a
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• pp.288-293
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• 2007

미국 911 테러 발생 이후로, 국가 기반시설(예: 송/배전 전력망, 석유/가스 파이프라인, 원자력 발전소, 정보통신 시설, 교통 시설, 금융 시설, 매스미디어 시설 등)에 대한 테러리스트의 사보타지 리스크를 관리하는 도전문제에 정부 차원이나, 기업 차원에서 국내외적으로 뜨거운 이목이 집중되고 있다. 그 가운데 에너지 시스템, 특히 원자력 발전소의 물리적 보안은 국가 안보 차원에서 매우 중대한 이슈가 되고 있다. 이는 사보타지로 인한 이러한 시스템의 파손이 국민, 작업자, 또는 외부 환경에 방사성물질 누출과 같은 중대한 결말을 초래할 수 있기 때문이다. 원전과 같은 복잡 시스템에서 설계 기준 위협이 초래할 수 있는 이러한 결말은 그 시스템의 특정 핵심 표적(예: 부품, 구역, 자산, 행위, 인원)의 방호를 통해 효과적으로 방어될 수 있다. 다시 말하면, 표적 인식에서는 어떻게 방어할 것인가에 앞서서 무엇을 방어할 것인가를 다루려는 것이다. 이 연구의 주요 목적은 여태까지 개발된 다양한 표적 인식 기법의 개발 추세를 소개하고 향후 전망을 제시하는 데에 있다. 이를 통해 표적 인식 기법의 수월성, 신뢰성, 및 경제성을 제고할 수 있으리라 본다. 표적 인식 기술의 활용성 측면에서 볼 때, 표적 인식은 하드웨어 적이거나 소프트웨어적인 방호 시스템의 설계에 필수적이므로, 신뢰성 높은 표적 인식은 다음과 같은 긍정적인 파급 효과를 줄일 수 있다: 1) 사보타지 리스크 감소에 직간접적으로 기여할 수 있다; 2) 제한적인 보안 재원을 효율적으로 할당할 수 있다; 3) 보안 대응군대의 훈련 시나리오를 개발할 수 있다; 4) 발전소 규제요건인 안전조치 계획을 비용이나 보안 측면에서 향상시켜 국민 안심(public easiness)을 도모할 수 있다. 향후에는 보다 더 광의적인 복잡 시스템 사이에서 상호 연계적인 사보타지에 대한 표적 인식의 기법들이 점검될 필요성이 있다고 본다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.231-236
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• 2014

With the development of industry these days, the demand for electric power increases and the larger capacity for power transfer is required. The scales of facilities should become larger; and the relative systems are required to operate with a higher degree of reliability. Therefore, stabilization of electric power systems is an important issue. The high degree of reliability required in the process of production and supply of electric power is an essential part of industrial society. Accident such as blackouts causes a hugh amount of economic losses to the high-tech industrial society dependent upon electric power. In this paper, in order to determine a stable operation of high-voltage power cable, used as a unique means of delivering electric power generated at a power station, we figure out the time rate of change of insulation resistance following a decay accelerating factor Arrhenius equation. With the data from the insulation resistance, we can determine the lifetime of power cable in operation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.277-281
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• 2007

We investigated fault current limitation characteristics of the resistive superconducting fault current limiter (SFCL) which consisted of a Bi-2212 bulk coil and a shunt coil. The Bi-2212 bulk coil and the shunt coil were connected in parallel. The Bi-2212 bulk coil was placed inside the shunt coil to induce field-assisted quench. The fault test was conducted at an input voltage of $200V_{rms}$ and fault current of $12kA_{rms}\;and\;25kA_{rms}$. The fault conditions were asymmetric and symmetric, and the fault period was 5 cycles. The test results show that the SFCL successfully limited the fault current of $12kA_{rms}\;and\;25kA_{rms}$ to below $5.5{\sim}6.9kA_{peak}\;within\;0.64{\sim}2.17$ msec after the fault occurred. Limitation was faster under symmetric fault test condition due to the larger change rate of current. We concluded that the speed of fault current limitation was determined by the speed of current rise rather than the amplitude of a short circuit current. These results show that the Bi-2212 bulk coil is suitable for distribution-class SFCLS.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.929-934
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• 2015

Because of the recent rapid advances in the development of ships with a larger proportion of electrical and electronic equipment, The usable frequency spread spectrum on ships is global trend. Therefore, concerns have been raised regarding the possible hazardous health effects of electromagnetic fields radiating from electronic devices. Although studies and investments on electro-magnetic fields in terrestrial areas are being conducted, they are not applied to a ship. In this paper, we measured electromagnetic fields in ship propulsion systems, and we analyzed the measured values against Korean and international standards. While the measured results satisfied the Korean standard, the Italian standard was not met in the switchboard area. However, the measured values were close to meeting the Italian standard. Therefore, further studies should be conducted for performing a comparative analysis of data in order to specify a standard of electromagnetic fields in propulsion systems that can be applied in the construction of government infrastructures.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.288-294
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• 2011

In this paper, the FPGA-based SoC board (Xilinx Virtex-4 ML401 EVM) is adopted to control electrical power inverter system. For marine application, its performance is shown on PC-based system for monitoring electrical characteristics of a power inverter using by the NMEA 2000 protocol. This power inverter system is achieved in Real-Time monitoring and control by dual micro-processor operation on embedded FPGA-based SoC board. One micro processor is for control (Control processor) electrical power inverter using by PWM signal. And the other microprocessor (Communication processor) is for communication with PC-based monitoring system. The two-processor is communicating each other using by dual-port ram (DPRAM). PC-based system user can control and monitor information of the electrical power inverter via NMEA 2000 based communication processor. Control and monitoring information includes the inverter status and configuration. SoC board converts this information to Parameter Group Numbers (PGNs) in the NMEA 2000 protocol. This system can be applied to marine power electronics for distributed power generation, transmission or regulation systems on the ship.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.173-179
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• 2001

This paper represents the control algorithm of the instantaneous voltage sag corrector for the power quality enhancement in distribution line. Especially, a novel detection technique of the symmetrical components is proposed for the analysis of the three-phase unbalanced and asymmetrical problems caused by the single line ground fault which is he most frequent event. This proposed method is based on the simple calculation and the control references of the symmetrical components for voltage compensation can be described as dc value without any other phase detection procedure. And also, for the generation of the reference voltages, the UF and MF defined by IEC is considered. Using this proposed control algorithm, the compensator has the fast dynamic characteristics and the THD of the compensated voltage waveform is very low. Finally, the validity of the proposed algorithm is proved by the PSCAD/EMTDC simulation and experimental results.