• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.85-91
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• 2021

With the social atmosphere of respect for human life and the increasing interest in safety of field workers, research and development is underway in various ways to transform direct live method into indirect live method in the field of distribution. As part of this measure, it was necessary to convert electric pole and complex facilities work from machining power distribution to indirect live operation, and install a straight connecting sleeve that connects cut wires for by-pass method, but it failed to meet the tensile strength standard when constructing a sleeve constructed by direct method. In this paper, the design factors were derived based on the case of overseas similar sleeves and the tensile strength evaluation of each variable was performed, based on the analysis of these test results, the method for securing tensile strength of straight-line access sleeves for indirect running was presented.

• Corrosion Science and Technology
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• v.17 no.2
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• pp.54-59
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• 2018

The effect of external DC electric field on atmospheric corrosion behavior of zinc under a thin electrolyte layer (TEL) was investigated by measuring open circuit potential (OCP), cathodic polarization curve, and electrochemical impedance spectroscopy (EIS). Results of OCP vs. time curves indicated that the application of external DC electric field resulted in a negative shift of OCP of zinc. Results of cathodic polarization curves measurement and EIS measurement showed that the reduction current of oxygen increased while charge transfer resistance ($R_{ct}$) decreased under the external DC electric field. Variation of OCP negative shift, reduction current of oxygen, and $R_{ct}$ increase with increasing of external DC electric field strength as well as the effect of external DC electric field on double-layer structure in the electrode/electrolyte interface and ions distribution in thin electrolyte layer were analyzed. All results showed that the external DC electric field could accelerate the corrosion of zinc under a thin electrolyte layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.225-230
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• 2020

Recently, with the miniaturization of GIS, there is a need for the miniaturization of spacers as accessories. Miniaturized spacers make it difficult to secure adequate insulation distances, resulting in a more concentrated electric field at the triple junction of high-voltage (HV) conductor-insulator (spacer)-insulation gas (SF₆), which is a weakness in GIS. Therefore, by introducing a new concept design technology, functionally graded material (FGM), which is recently applied to various materials and parts industries, three-dimensional control of the dielectric constant distribution in a spacer can be expected to alleviate triple-junction electric field occupancy and improve insulation performance. In this study, we propose an optimized model using NSGA-II to optimize the permittivity distribution of FGM applied spacer.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.87.1-87.1
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• 2012

We use three-dimensional magnetohydrodynamic simulations to investigate how the dynamic state of emerging magnetic field is related to the twist of field lines. Emergence of magnetic field is considered as one of the key physical process producing solar activity such as flares, jets, and coronal mass ejections. To understand these activities we have to know dynamic nature and electric current structure provided by emerging magnetic field. To demonstrate dynamic nature of field lines, we focus on the factors such as curvature of magnetic field line and scale height of magnetic field strength. These factors show that strong twist case forms two-part structure in which the central part is close to a force-free state while the outer marginal part is in a fairly dynamic state. For weak twist case, it still shows two-part structure but the tendency becomes weaker than strong twist case. We discuss how the curvature distribution affects the dynamic nature of emerging magnetic field. We also investigate electric current distribution provided by emerging field lines to show a possible relation between electric current structure and sigmoid observed in a preflare phase.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1652-1657
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• 2010

This paper analyzes optimal stirrer parameter to improve field uniformity in a mode-stirred reverberation chamber. Stirrer parameter is varied about stirrer height and stirrer angle. Also we analyze quality factor, number of excited modes and stirrer efficiency that affect field uniformity. The results show good performance as higher as stirrer height. Isotropic field distribution is formed at $45^{\circ}$ stirrer angle. When stirrer angle varies, scattering characteristic of incident wave are changed. So electric field distribution in a mode-stirred reverberation chamber is also changed. Therefore, it affect field uniformity. The results expect to help that designs stirrer for get better field uniformity. Immunity test performed designed mode-stirred reverberation chamber for semiconductor that categorized by technology. Test result shows that good recurrence compared wave-guide immunity test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.9-17
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• 2001

A numerical study has been carried out on the evolution of the particle size distribution for unipolar charged particles that experience coagulation in an alternating electric field. The collision frequency function of charged particles was analytically derived. The log-normal size distribution function is utilized for representing a poly-disperse size distribution and the moments of the particle size distribution are used to solve the general dynamic equation considering only AC electric force effect. The results are compared with the effects of brownian coagulation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.10
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• pp.693-698
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• 1999

Vacuum interrupters have a special asymmetric electrode structure to generate an magnetic field and consequently to increase the interrupting ability. Accordingly 2-dimensional analysis has a large analysis error because radial flux can not be considered. In this paper, in order to analyse the electric field distribution of a vacuum interrupter with arc shield more accurately, 3-dimensional finite element method(FEM) is used. The induced electric potentials of floating shield was increased with the gap distance, which is because the relative position of shield is closer to the fixed contact so that the capacitance distribution inside interrupter is varied. The calculated results also show that the induced potential of shield causes electric field distortion so that the maximum value of electric field in a vacuum interrupter with arc shield is higher than that without one.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.603-606
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• 2004

Aspects of PD occurrence from PD sources are different with their physical and structural appearances which cause the variation of electric field distributions of them. This paper have investigated electric field distributions of some kinds of electrode structure by FEM applied analysis program. Numeric analysis is a good method to investigate Ihe electric and magnetic field distribution of partial discharge source. The analysis results were confirmed by real PD occurring situation in the laboratory.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1901-1902
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• 2006

In recent years, it has been a worldwide trend that many power utilities gave their attention to develop and operate their power plants, substation and distribution systems. Following this trend, KEPCO(Korea Electric Power Corporation) has developed many electric automation systems with various communication networks. It has been natural that the automation systems are just focused on to remote devices when they come to be designed. But, we have to shift the focus to the automation system itself. We have developed the Multi-service Optical Transmission System (M-OTS) for electrical power systems. It can be adopt to not only distribution power field but also the transmission power field. The result strongly shows that the system is potentially beneficial in reliability, speed, and expandability. This paper presents some of initial design efforts and results toward a KEPCO's communication system in distribution areas.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1653-1655
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• 1998

In this paper, measurement and analysis of ELF electric and magnetic fields in the vicinity of 22.9[kV] distribution line have been performed. The height of measuring point from the earth's surface was 1[m], and the distance between the device and the operator was more than 3[m]. The experiments have been carried out by lateral profile, and we have made use of FIELDS program for the sake of comparision the experimental data with the theoretical value. Electric and magnetic fields intensity were strong under a distribution line, and were inversely proportional to lateral distance. The profiles of electric field were M shape and those of magnetic field were $\cap$ shape. Electric and magnetic fields intensity were increased with increasing the measurement height.