• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.67-74
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• 2005

Grounding insures a reference potential point for electric devices and also provides a low resistance path for fault currents in the earth. The ground impedance as a function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. In this paper, the ground impedance of Magic rods which are commercially available has been measured in frequency ranging from 0[Hz] up to 100[kHz] and an equivalent circuit model, transfer function model of the ground impedance are identified from the measured values.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.46-51
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• 2005

Grounding insures a reference potential point for electric devices and also provides a low resistance path for fault currents in the earth. The ground impedance as a function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. A cower rod electrode is the most commonly used grounding electrode in electric distribution systems. In this paper, the ground impedance of cower rods has been measured in frequency ranging from 60[Hz] up to 100[kHz] and an equivalent circuit model, transfer function model of the ground impedance are identified from the measured values.

• The Journal of Information Technology
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• v.1 no.2
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• pp.15-24
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• 1998

C.I.F. and F.O.B. contracts are the chief terms used in international trade contracts. But, in recently, the multimodal transport which is based on the containerization and the improvement of air transport has been grown gradually, Regardless of theese change in international trade environment, most of the contract of sale is made by C.I.F. and F.O.B. contracts which are based on the traditional port to port transport. In other words, there are some limitation in terms of legal base in which traditional C.I.F. and F.O.B. contract is applied to the changed environment. Especially, problems arised in marine insurance which export by F.O.B. trade terms. Therefore, when the parties of the contracts of sale make an sale contracts by using the container ship and Multimodal Transport, they should use the F.C.A. and C.I.P. contracts Instead of F.O.B. and C.I.F. contracts for the transport of goods. And parties of the contracts of sale need to gain a better understanding of the characteristic of F.C.A. and C.I.P. terms and the problem of the F.C.A. and C.I.P. contracts used in the performance on international multimodal transport.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.60-67
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• 2004

With the proliferation of nonlinear loads, high neutral harmonic currents in three-phase four-wire distribution system have been observed It has been also known that the ground impedance has an effect on the neutral currents of a system which operates with harmonics present. On-site measurements of harmonic currents and voltages, and the soil resistivity and ground resistance under case study system were made and the corresponding equivalent circuit for the harmonics analysis was developed This equivalent circuit model was simulated numerically and graphically through the use of MATLAB and CDEGS software packages, and adequate results were obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.97-103
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• 2011

The most important object of grounding systems is to protect human being from electric shock. Touch and step voltages are measured to evaluate the performances of grounding systems. Dangerous voltages have been largely studied by the power frequency fault currents, on the other hand, the ground current containing the high frequency components and surge currents haven't been considered. Many attempts about the grounding impedances reported in these days show that the performance of the grounding systems in high frequency range is very different with the ground resistance. It is necessary to analyze the dangerous voltages formed by the ground currents containing high frequency components. In this paper, the ground surface potential rises near the vertical and horizontal grounding electrodes are measured at the frequency of 100[Hz], 30[kHz], and 100[kHz]. Dangerous voltages are investigated with the frequency-dependent grounding impedance. As a result, the ground surface potential rise is increased as the grounding impedance increases. Touch and step voltages near the grounding electrode whose impedance increases with the frequency are sharply raised.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.117-123
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• 2011

Lightning and switching surges propagating through the grounding conductors lead to transient overvoltages, and electronic circuits in information technology systems are very susceptible to damage or malfunction from the electrical surges. Surge damages or malfunctions of electrical and electronic equipment may be caused by potential rises. To solve these problems, it is very important to evaluate the ground surface potential rises and hazardous voltages such as touch and step voltages at or near the grounding systems energized by electrical surges. In this paper, the performance of grounding systems against the surge current containing high frequency components on the basis of the actual-sized tests is presented. The ground surface potential rises and hazardous voltages depending on impulse currents for vertical or horizontal grounding electrodes are measured and analyzed. Also the touch and step voltages caused by the impulse currents are investigated. As a result, the ground surface potential rises, the touch and step voltages near the grounding electrodes are raised and the conventional grounding impedances are increased as the front time of the injected impulse currents is getting faster.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.113-119
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• 2010

A safe grounding design is used for providing means to carry electric currents into the earth under fault conditions without exceeding any operating limits and for assuring that a person in the vicinity of grounded facilities is not exposed to danger of critical electrical shock. Transformer neutral point grounding is for the purpose of controlling the voltage to earth within tolerable limits under a line-to-ground fault. Transformer frame grounding is for the purpose of minimizing the hazardous potential within safety criteria appearing at the faulted equipment. ills paper deeply investigates the grounding resistance effects of distribution power transformers by analysing the neutral to eatth voltages and touch voltages when the fault occurs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.208-213
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• 2010

This paper deal with an analysis of the ground surface potential profiles using a hemispherical scaled-model. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the ground surface potential profile around the grounding electrodes according to the configuration of grounding electrodes. In this work, a hemispherical vessel with a diameter of 1,100 [mm] was employed to simulate uniform soil and CDEGS program was employed to compare the measured and simulated results. As a result, the ground surface potential around the grounding electrode was significantly raised and the ground surface potential at the just upper point of ground electrode particularly was higher than other points. The ground surface potential of counterpoise was higher than other grounding electrodes such as mesh and grounding rods and the ground surface potential strongly depends on the frequency responses of grounding electrodes. Also the results measured with the small-sized model were in reasonably agreement with the data obtained from simulation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.7
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• pp.319-325
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• 2005

In order to analyze ground potential rise of grounding system installed in buildings, the hemispherical grounding simulation system has been designed and fabricated as substantial and economical measures. Ground potential rise(GPR) has been measured and analyzed for shapes of grounding electrode using the system in real time. The system is apparatus to have a free reduced scale for conductor size and laying depth of a full scale grounding system and is constructed so that a shape of equipotential surface is nearly identified a free reduced scale with a real scale when a current flows through grounding electrode. The system was composed of a hemispherical water tank, AC Power supply, a movable potentiometer, and test grounding electrodes. The test grounding electrodes were fabricated through reducing grounding electrode installed in real buildings such as rod type, mesh grid type. When a mesh grid type was associated with a rod type, GPR was the lowest value. The proposed results would be applicable to evaluate GPR in the grounding systems. and the analytical data can be used 0 stabilize the electrical installations and prevent the electrical disasters.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.53-56
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• 2009

본 연구는 생태면적률을 교육시설에 적용하기 위한 프로세스 개선에 관한 연구로 수행되었다. 생태면적률은 최근 시행되기 시작한 개발사업에 대한 환경지표로 생태환경보전에 매우 중요한 역할을 담당할 것으로 전망되고 있다. 본 연구에서는 관련 선행연구 및 제도, 기준고찰을 통하여 생태면적률에 관한 국내외의 동향을 파악하고, 교육시설에 생태면적률을 적용하기 위한 실태파악을 위하여 일차적으로 중부권 C시의 초등학교를 중심으로 적용된 대지 및 체육장 면적분포, 교지 대비 체육장 비율, 조경면적, 친환경 인증 등에 관한 현황조사를 수행하였다. 본 연구의 실태조사 결과를 통하여 교육시설의 부지조성 특성에 따른 부지유형을 도출하였고, 부지유형별 생태면적률 적용 프로세스를 제안하고, 제도적 적용을 검토하기 위하여 공공부문의 도시 건축 및 환경분야 종사자 및 건축사의 생태면적률에 관한 인지도를 알아보기 위한 설문을 수행하였다. 본 연구의 결과 교육시설의 계획특성에 부합되는 생태면적률 적용 프로세스를 제안하였다.