• Journal of the Korean Institute of Gas
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• v.8 no.4 s.25
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• pp.62-69
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• 2004

It is necessary to eliminate the electric static for the prevention of disasters by electric static discharge, the improvement of production efficiency, the protection of a sensitive electronic devices in the variable manufacturing processes. Then it is handled for elimination of electric static in the painting plant, the film manufacturing plant, the producing semi-conductor factory. This study described on the ideal condition of electric static elimination efficiency by changing of the length of voltage input type eliminator's bar, the length of copper pipe and the gap of electrode and the existence of explosion by inflammable gas with that conditions. As the result, the electric static elimination efficiency has the most ideal value at the 8-11(mm) gap of the earth electrode and needle type electrode each elimination bar and there is not explode at the explosive experiment of inflammable gas with the ideal elimination bar. We can consider that there are some data which are needed for elimination efficiency and it will be able to protect the occurrence of explosion accident inflammable nas in the industrial fields.

• Journal of the Korea Society for Simulation
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• v.29 no.1
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• pp.23-30
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• 2020

In this paper, we theoretically examine the characteristics of an Artificial Magnetic Conductor (AMC) constructed of a perfect electric conductor and a normal material having permittivity ε_r, permeability μ_r, and thickness L. First, we derived rigorous equations to describe the infinite AMC structure. Then, we studied how the AMC's characteristics are affected by changes in ε_r, μ_r and L. The operating center frequency exhibiting a 0° reflection coefficient phase occurs when L is one quarter of a guide wavelength. Therefore, the AMC thickness can be reduced by using a material having a high product of ε_r and μ_r. As the ratio μ_r/ε_r increases, the bandwidth of the AMC increases (maximum value: 200 %), and its operating frequency decreases. We also find out he bandwidth of the AMC is improved by introducing a loss in the material. To validate the AMC, we design a dipole antenna on the AMC and demonstrate a relationship between AMC phase and dipole antenna's operating frequency by investigating the dipole on the AMC with different pairs of ε_r and μ_r.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.566-572
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• 2021

A methodology for the identification and coordinates estimation of air cavities under urban ground or sandy soil using its natural poles and natural resonant frequencies is presented. The potential of this methodology was analyzed. Simulation models of PEC (Perfect Electric Conductor)s with various shapes and dimensions were developed using an EM (Electromagnetic) simulator. The Cauchy method was applied to the obtained EM scattering response of various objects from EM simulation models. The natural poles of objects corresponding to its instinct characterization were then extracted. Thus, a library of poles can be generated using their natural poles. The generated library of poles provided the possibility of identifying a target by comparing them with the computed natural poles from a target. The simulation models were made assuming that there is an air cavity under urban ground or sandy soil. The response of the desired target was extracted from the electromagnetic wave scattering data from its simulation model. The coordinates of the target were estimated using the time delay of the impulse response (peak of the impulse response) in the time domain. The MP (Matrix Pencil) method was applied to extract the natural poles of a target. Finally, a 0.2-m-diameter spherical air cavity underground could be estimated by comparing both the pole library of the objects and the calculated natural poles and the natural resonant frequency of the target. The computed location (depth) of a target showed an accuracy of approximately 84 to 93%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1025-1033
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• 2011

In this paper, we introduce the contactless power transmission device for transmitting the power with the resonant characteristic of the cavity resonator. When transmitting the power, the contactless power transmission device begins to work in the condition where the transceiver adheres closely. The transceiver is electrically separated because there is no conductive terminal outside and the size of the receiver required for the electric power transmission can be minimized. The cavity resonator comprises slots for the input port and output port in the upper side conductor plate of the cavity and forms the input port and output port using the stripline structure at this upper part. The some of output port is separated from it and the electric power receiver is formed thus the union can be possible. The rest except electric power receiver become the electric power transmitter, which includes the input port of stripline-slot coupling, cavity, and the slot of the output port. If the transmitter and the receiver are combined, they become the form in which the electricity is transferred from the input port to the output port in a cavity resonator. The center frequency of the contactless power transmitter manufactured is 5.782 GHz. and $S_{21}$ is measured as -1.07 dB. It is confirmed that the high electric power transfer rate is approximately 78 %.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.141-147
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• 2019

Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.75-81
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• 2000

This paper describes the partial discharge due to particles in $SF_6$ gas. A model GIS chamber was designed and manufactured. The partial discharge and breakdown phenomena due to the particles between electrodes were observed and partial discharge signals were detected, using an ultrasonic sensor. The analysis of the electric field by the states of the particle inserted between the electrodes, were also carried out. The partial discharge was observed at end while the particle was moving in $SF_6$ gas. The partial discharge in micro-gap grows to arc, and after all, it can cause a breakdown.The electric field strength was the highest in case that the particle was vertically attached on the conductor, and the lowest in case that it was horizontally attached on the enclosure.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.230-236
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• 2015

In this paper, the electric potential of electrode surface is investigated by assuming them as two dimensional sets of point current sources. And, the simulated water tank is manufactured as a reduced scale of the earth. Henceforth, the adequate model electrode for test is decided to decrease experimental errors relevant to the limitation of the size of the water tank. The one of important things of this work, the deduction method of the potential interference factor is proposed, which used as the criterion of the potential interference according to the shape of conductors and the laying conditions, when multiple grounding conductors are situated at the same resistance grounding area. Also, the validity of this theory is verified from a numerical simulation of the grounding electrode to be used in experiments, and this study is realized by the verified theory and the simulated experiments.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.122-124
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• 2005

Underground distribution system is a trend due to the successive development of metropolitan area and satellite cities and the environment of the commercial and residential areas. The high quality of electricity, which is related with the minimal outage duration time due to the maintenance work for the underground distribution line, is mandatory. Hence, the construction method and tools for the outage-free maintenance construction have been required for underground distribution system. So far, all the efforts for outage-free maintenance for the underground distribution have been limited only to the survey for foreign countries situation and the theoretical provision; thus, It is required to develop the various construction method and the application tools. Differently from the aerial line, the construction of the underground cable is complicated and the insulation distance between conductor and shield should be maintained in loadmaking/breaking operation, though the apparatus connected with cable is a deadfront type. Also since the apparatus is installed above ground, by-pass of faulted area at busy area needs a variety of high technologies. Therefore, in this these, the authors introduce the development status of the loadbreak connectors, connection facilities, outage-free maintenance system for secondary side, a secondary auxiliary bushing and additional tools so that there can be more progress on this field.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.9
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• pp.701-706
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• 2018

The characteristic basis function method, or CFBM, is one of the representative electromagnetic methods widely used today. In this paper, we propose an accelerating algorithm for the far field interaction calculation of CBFM, to efficiently analyze the electromagnetic characteristics of arbitrarily large structures. To effectively analyze the electromagnetic characteristics of a large structure, it is essential to shorten the computation time. In the CBFM analysis method, the complexity can be greatly reduced by using approximations created via the multipole expansion method. The new algorithm proposed in this paper is applied to the computation of radar cross sections of conductor spheres and fighter aircraft, and it is confirmed that calculation time is reduced by 34 % and 74 %, respectively, without loss of accuracy compared with existing CBFM.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.535-542
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• 2000

Pure copper, Cu-1.1wt%Cd and ACSR(Aluminum Conductor Steel Reinforced) have been used as Catenary Materials in Electric Railway System. Since these materials may have chance to be exposed to the corrosive environments like polluted air, acid rain and sea water, it is important not only to investigate the corrosion characteristics but also to measure corrosion rates in various corrosive environments. In order to examine corrosion characteristics according to the dissolved oxygen content, pH, chloride ion concentration ion, and the addition of Cd to Cu, a series of tests such as potentiodynamic polarization. a.c impedance spectroscopy and galvanic corrosion tests were carried out in these materials. Results showed that the addition of Cd to Cu and chloride ion in the solution have an adverse effect on the resistance to corrosion. Additionally, Galvanic currents between Al and steel wires of ACSR were confirmed by using ZRA(zero resistance ammeter) method.