• Proceedings of the KSR Conference
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• 2003.10c
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• pp.507-512
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• 2003

Even if tracks cross each other, a train has to maintain a good current collection. Where catenary cross each other, it is called a crossover. Based on the cause analysis for a breakdown accident of pantograph occurred in the crossover on Ansan-line, a theoretical background and recommendation for the installation rule of a crossover are presented in the paper.

• Journal of Information Technology Services
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• v.10 no.4
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• pp.259-268
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• 2011

A robot education system by emulation based on Web can be efficiently used for understanding concept of robot assembly practice and control mechanism of robot by control programming. It is important to predict the path of the line tracer robot which has to be decided by the robot. Shortest Path Algorithm is a well known algorithm which searches the most efficient path between the start node and the end node. There are two related typical algorithms. Dijkstra Algorithm searches the shortest path tree from a node to the rest of the other nodes. $A^*$ Algorithm searches the shortest paths among all nodes. The delay time caused by turning the direction of navigation for the line tracer robot at the crossroads can give big differences to the travel time of the robot. So we need an efficient path determine algorithm which can solve this problem. Thus, It is necessary to analyze the overhead of changing direction of robot at multi-linked node to determine the next direction for efficient routings. In this paper, we reflect the real delay time of directional changing from the real robot. A speed based Dijkstra algorithm is proposed and compared with the previous ones to analyze the performance.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.151-159
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• 2003

According to the records, approximately 50 percent of power failure were caused by lightning. Conventional fault preventive measures against lightning include reduction of the footing resistance of the tower, multiplication of overhead ground wires and unbalanced insulation of the double circuit transmission tower. In addition to these, transmission line arresters have been recently appeared as an alternatives. In this paper an unbalanced insulation method with transmission line arrester was assumed as another countermeasure against simultaneous double circuit trip of 154 kV transmission line by lightning strike. The lightning performance of line arrester was compared with conventional insulation concept using different numbers of porcelain and glass insulator. Larger numbers of insulator simply increase flashover current level by lightning but the lightning performance doesn't proportional to it. EMTP simulation and predictive calculation of lightning failure rate were carried out to evaluate the performance.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.1
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• pp.5-14
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• 2002

In this paper, we analyze inductive interference in conductive material around 345 kV power transmission line, and evaluate the effects of mitigation wires. Finite element method (FEM) is used to numerically compute induced eddy currents as well as magnetic fields around powder transmission lines. In the analysis model, geometries and electrical properties of various elements such as power transmission line, buried pipe lines, overhead ground wire, and conducting earth are taken into accounts. The calculation shows that mitigation wire reduces fairly good amount of eddy currents in buried pipe line. To find the optimum magnetic field shielding location of mitigation wire, we applied evolution strategy algorithm, a kind of stochastic approach, to the analysis model. Finally, it was shown that we can find more effective shielding effects with optimum location of one mitigation wire than with arbitrary location of multi-mitigation wires around the buried pipe lines.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1761-1769
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• 2010

This paper describes switching surge analysis on reclosing decision in 154kV combined transmission line with power cables. Reclosing should be operated in combined transmission line based on the technical evaluation because of insulation problem of power cable section. If the surge strikes on power cable, the breakdown can occur at week point of cable insulation. Therefore the detailed analysis is required by considering several conditions such as length ratio of power cable, arrester, fault resistance, charging rate and grounding resistance, etc.. In addition, sheath voltage on IJ(Insulated Joint) is analyzed to confirm the protective level. Simulation is performed by EMTP/ATP. Analysis results show that reclosing can be operated without any special problem by the single line-to-ground fault with fault resistance of $1\Omega$ to $50\Omega$ occurred at the overhead transmission section in 154kV combined transmission lines and trap charge of 100% and 110%.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.1
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• pp.38-42
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• 2017

The wear of the third track power collector is one of the essential check factors for safe train operation. Rapid wear of the current collector accelerates the line of the catenary. In addition, the arc generated when the catenary line is turned off causes a malfunction in the minute portion of the catenary line, thereby shortening the life of the catenary line. In this paper, to analyze the mechanical wear of the current collector during driving according to the environmental factor of the Maglev(magnetic levitation train), it was divided into dry season and wet season. the wear of metallized collector, copper alloy collector and carbon collector were measured and compared with each other. The wear rate was measured according to the position of the wire, the position of the power collector and the position per hour. Microscopic photographs of the cross section and surface of the power collector were measured. The electrical currents of the metallized collector, copper alloy collector and carbon collector were measured.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.870-875
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• 2013

After introducing diagnosis equipment power failure prevention activities for distribution system have become more active. To do facility diagnosis and maintenance work more efficiently we need to evaluate reliability for the system and should determine the priority line with appropriate criteria. Thus, to calculate risk factor for the power distribution line that are composed of many component facilities its historical failure events for the last 5 years are collected and analysed. The failure statics show that more than 60% of various failures are related to environment factors randomly and about 20% of the failures are refer to the aging. As a strategic evaluation system reflecting these environmental influence is needed, a system on the basis of the probabilistic approach related statical variables in terms of failure rate and failure probability of electrical components is proposed. The figures for the evaluation are derived from the field failure DB. With adopting Bayesian rule we can calculate easily about conditional probability query. The proposed evaluation system is demonstrated with model system and the calculated indices representing the properties of the model line are discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1818-1823
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• 2015

In this paper, we analyzed the optimal configuration of protection wire that have been installed in the electric railway power supply system. Protection wires are to suppress the ground potential rise when the short circuit fault between contact wire-rail(C-F), and protect the electronics equipments(signalling and communication) that are facility the wayside. The role of protection wires must be feed back quickly the fault current to the substation when a short circuit fault occurs. In this paper, we proposed that only one line to install the protection wire. Comparing how to newly proposed and existing system, most of the performance is similar. The reason is that most of the current flowing in the protection wire near the location where the fault occurred. There is no problem even if in one line for human safe and the low impedance of the return circuit in dimension to ensure the safety of the facility during the fault. To ensure safety during an fault occurs, it is sufficient even by one line. But, In the protection wire of facilities planning it is necessary to design taking into account the potential utility.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.696-698
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• 2007

As overhead transmission lines are exposed to the outdoor weather, lightning induced fault accounts for about 66% of faults in transmission lines. The lightning may cause the damage of power system apparatus or the shut down of electricity. Not only in order to decrease the damage of the power system itself but also to ensure the reliable power supply, an appropriate insulation design based on the long-term lightning statistics is required. Meanwhile, real time information of lightning might be more useful to quickly locate the point of lightning induced fault in the line, leading to minimization of the adverse effects derived from the fault. Korea Electric Power Corporation has been providing an on-line lightning information service, named as KLDNet, since 2006 in order to meet the need inside our company. This paper describes the development and application of the information system.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1035-1037
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• 2005

The analysis of magnetic fields(2-D) induced by line currents, such as Overhead Trolley Lines or Transmission Lines, is not so easy by using the standard Finite Element Method(FEM). Mesh generation is one of the most important processes in the standard FEM. Because, the current region is relatively small compared with whole region, and actually is a line without thickness, the mesh refinement around the source lines yields many demerits. A way of supplement such a defect, we proposed the coupling scheme of analytical solution and FEM. In this study, the analytical solution is adopted around the region of line currents and FE solution is a lied to the rest of source region. And the two types of solution are coupled at the artificial boundary. To verify the usefulness of proposed algorithm, simplified model with magnetic material in FE region is chosen and analyzed. The results are compared with those of standard FEM. And the errors between them can be reduced by increasing harmonic orders.