• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.246-251
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• 1998

This paper describes the main features of an unconventional tester for high power semiconductor devices. Two application ranges are highlighted. The tester is used for the extraction of GTO parameters and their verification by measurements. The second field comprises the determination of the radial and azimuthal current density distribution of a GTO tablet. The results are compared with the carrier lifetime distribution.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.231-239
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• 1987

Distribution system is one of large and complicated sytem, consisted of a great number of components. Therefore efficient operation based on precise analysis and computation methods is indispensable accommodating growing loads. This paper describes an optimal operation problem to relieve overload flow in radial distribution systems by using modified block model. The problem is formulated as a network problem of synthesizing the optimal spanning tree in a graph, branch and bound method is used for the optimization. Especially modified block model proposed in this paper is validated more practical than conventional model. These methods can be applied to two types of distribution system problems such as, 1) planning problem to check the capability of relieving overload at normal rating, 2) emergency operation problem to determine switching scheme for minimizing customer loads affected by a fault. Examples of application to these problems are discussed.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.453-453
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• 2000

This paper presented Fuzzy logic application to Electrical power system analysis for fault location estimation in distribution lines and apply the Power system theory to be fuzzy logic database. The case study referred to the Overhead distribution line of the Provincial Electricity Authority (PEA.), Thailand which mostly the distribution line of PEA. are Radial schemes. These benefits include reduced outage time, help in locating momentary faults, enhance safety to the line crews and provide notification of an outage without receiving calls from the consumer, Which these benefits also increase Reliability, Stability and Efficiency.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.861-863
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• 1997

This paper presents a reliability and power quality taken account of the reclosing scheme on the power distribution system. To determine the optimal reclosing scheme, the simple radial distribution system is modelled, and analyzes quantitatively the effect of customer's load to the number of reclosing. The result of the analysis shows that the determined reclosing scheme can satisfy both the reliability and the power quality in the power distribution system.

• Journal of ILASS-Korea
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• v.9 no.2
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• pp.1-8
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• 2004

This work was performed to investigate the distribution of the fuel droplet size around the bluff-body and the combustion characteristics. The geometry of the bluff-body influenced the spray shape and the combustion characteristics. Diameters of the bluff-body in this experiment are 6, 8, and 10 mm and the impingement $angles({\theta})\;are\;30^{\circ},\;60^{\circ},\;and\;90^{\circ}$. The measurement points were at the distances of 20 and 30 mm axially from the nozzle. The SMD and Rosin-Rammler distribution was acquired by image processing technique (PMAS), and the mean temperatures were measured by thermocouple. The results obtained are as follows; In the condition of ${\theta}=60^{\circ}$, the values of SMD are not greatly varied compared to the other conditions. As the impingement angle of bluff-body was increased, the high temperature region was wider along radial direction. When the air-fuel ratio was increased, the CO concentration was decreased.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.381-383
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• 2003

The authors have developed a solution method based on the incremental algorithm. The optimal load balance between feeders is found through the incremental algorithm with allowing the loop configuration. Therefore loops can be configured in the resulting configuration, and then we must eliminate all loops to satisfy radiality of distribution system because the distribution system is operated under radial status. But the optimal load balance through incremental algorithm is deteriorated when the loops are eliminated. In this paper, authors propose a new method which is to improve the searching procedure of path in the incremental algorithm, that is, so as not to make loop in the path configuration.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.488-490
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• 1995

This paper presents an optimization technique using genetic algorithms(GA) for loss minimization in the distribution network reconfiguration. Determining switch position to be opened for loss minimization in the radial distribution system is a discrete optimization problem. GA is appropriate to solve the multivariable optimization problem and it uses population, not a solution. For this reason, GA is attractive to solve this problem. In this paper, we aimed at finding appropriate open sectionalizing switch position using GA, which can lead to minimum transmission losses.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.4
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• pp.371-378
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• 1999

This paper presents an efficient algorithm for loss reduction of distribution system by automatic sectionalizing switch operation in large scale distribution systems of radial type. Simulated Annealing algorithm among optimization techniques can avoid escape from local minima by accepting improvements in cost, but the use of this algorithm is also responsible for an excessive computation time requirement. To overcome this major limitation of Simulated Annealing algorithm, we may use advanced Simulated Annealing algorithm. All constaints are divided into two constraint group by using perturbation mechanism and penalty factor, so all trail solutions are feasible. The polynomial-time cooling schedule is used which is based on the statistics calculation during the search. This approaches results in saving CPU time. Numerical examples demonstrate the validity and effectiveness of the proposed methodology.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.152-156
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• 2007

This paper proposes a method for real-time control of both capacitors and ULTC in a distribution system to reduce the total power loss and to improve the voltage profile over the course of a day. The multi-stage consists of the off-line stage to determine dispatch schedule based on a load forecast and the on-line stage generates the time and control sequences at each sampling time. It is then determined whether one of the control actions in the control sequence is performed at the present sampling time. The proposed method is presented for a typical radial distribution system with a single ULTC and capacitors.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.335-337
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• 1998

This paper presents a efficient algorithm for loss reduction of distribution system by automatic sectionalizing switch operation in distribution systems of radial type. Simulated Annealing can avoid escape from local minima by accepting improvements in cost, but the use of this algorithm is also responsible for an excessive computation time requirement. To overcome this major limitation of Simulated Annealing Algorithm, we may use advanced Simulated Annealing Algorithm. Numerical examples demonstrate the validity and effectiveness of the proposed methodology.