• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.305-308
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• 2008

This paper presents characteristics of soil ionization when high currents such as lightning and switching surge currents are injected into a grounding rod. Soil ionization phenomena are investigated by using both voltage and current signals recorded by oscilloscope. As a result, a critical electric field intensity($E_C$) for ionization is decreased with reduction of grain size. The pre-ionization resistance($R_1$) and post-ionization resistance($R_2$) at the sand with fine grain size are getting lower with increasing current magnitude. Finally, the time to ionization($t_1$) and ionization current peak($t_2$) of fine grain size are significantly shorter than those of medium grain size.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.95-99
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• 2004

A systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection systems is presented. The measurement and analysis of ground impedance are based on a computer aided technique. The magnitude and phase of ground impedance were measured and analyzed by the modified fall-of-potential method and the proposed computer program algerian using the waveforms of the test current and potential rise. The theoretical analysis of ground impedance were performed with the equivalent circuit models, and the theoretical results were compared with the measured data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1492-1493
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• 2006

Wenner 4-probe arrangement is used most widely by the method to measure soil resistivity and the measured data with the Wenner method are apparent resistivities of the soil. Therefore, the soil structure can be analyzed easily from the measured apparent resistivity, but the real soil resistivity is difficult to know correctly at a particular depth or at a specific location on earth surface. This paper introduces a method that can be used to decide the suitable burial depth and the electrode scale of a grounding rod effectively using soil structure analysis equipment based on the dipole-dipole method.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.63-66
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• 2009

Lighting currents are one of major influences on the dynamic performance of ground electrodes. High lighting current intensity changes in the dynamic grounding performance due to ionization of the soil and very fast fronted pulses. The previous analysis has often been based on quasi-static approximation that is not applicable to very fast fronted pulses. To extend the analysis to fast fronted pulses in this paper, the full-wave analysis method based in the rigorous electromagnetic-field theory approach is used and the effects of the ionization of the soil me disregarded. Based on the simulation results, the empirical formulas applicable for slow and very fast fronted lightning current pulses me reviewed; therefore the validity of the theoretical approach is verified through comparison between the calculated and measured results.

• 조명전기설비학회논문지
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• 제21권7호
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• pp.37-45
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• 2007

최근 뇌보호용 접지시스템 심매설 봉전극을 사용하는 경우가 늘고 있다. 심매설 봉전극의 경우에는 수직으로 깊게 봉전극을 시설하기 때문에 메시그리드 전극에 비해 장소의 제약을 덜 받는 장점이 있지만 국지적인 대지저항률에 의해 접지임피던스가 크게 변동하므로 설계시에 세밀한 대지구조의 분석이 필요하다. 기존의 Wenner법에 의한 대지저항률 측정은 널리 사용되는 방법이지만 국지적인 대지저항률의 변화를 알아내기가 불가능하였고 또한 겉보기 대지저항률로 측정결과가 나타나므로 정확한 깊이를 예측하기가 어렵다. 따라서 본 연구에서는 96채널 측정설비를 이용하여 대지구조를 2-D 이미지로 분석하였으며, 뇌보호용 심매설 전극을 효과적으로 설계하기 위해 국지적인 대지저항률 변동 및 대지층 깊이의 분석을 시도하였다. 대지저항률의 2-D 이미지 분석은 Wenner alpha법, Dipole-dipole법, Schlumberger법을 사용하였으며, 분석결과를 토대로 기존의 Wenner 1-D법으로 측정한 결과를 CDEGS로 분석한 대지구조와 비교하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1489_1490
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• 2009

Ground impedance is changed according to frequency of the current injected into the grounding system. Because the lightning surge gives a broad frequency spectrum from some ten Hz to a few MHz, frequency dependance of ground impedance must be evaluated. In this paper, we have constructed 10m, 30m, 50m counterpoise and evaluated frequency dependance of ground impedance. Also we have evaluated frequency dependance of ground impedance according to current injection point. As a result, long counterpoises have low ground resistance, but ground impedances of those are significantly increased in the range of high frequency. In the case that currents are injected into the center of counterpoise, the ground impedance is most lower than any other injection point. Also, additory ground rod of 1.8m long affect ground impedance decrease.

• 조명전기설비학회논문지
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• 제20권10호
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• pp.68-73
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• 2006

접지저항을 측정하는데 있어서 전류전극의 이격거리는 일반적으로 접지전극으로부터 전류전극에 이르기까지의 직선 구간상에서의 전압강하의 변화 곡선에 소위 평탄 구간이 존재하도록 이격하는 것으로 알려져 있다. 그러나 이러한 전류전극 이격 기준의 문제점은 그와 같은 조건을 만족하기에는 현실적으로 곤란한 측정 현장이 있다는 것이다. 이러한 문제의 보완을 위하여 본 논문은 실험적 측정 데이터를 활용, 분석하여 전류전극 이격거리의 최소 규격을 제시하였다. 분석 결과에 의하면 봉상접지에 대하여는 봉 길이의 2배 이상을, 메쉬접지에 대하여는 한 변 길이의 2배 이상 이격하여야 함을 알 수 있다.

• International Journal of Safety
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• 제5권2호
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• pp.18-23
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• 2006

Studies have claimed that ESE (Early Streamer Emission) air terminals offer a vastly increased zone of protection over that of traditional lightning rods (Franklin rods) by causing the emission of an upward streamer/leader: The upward streamer/leader will propagate towards the tip of the downward leader at an early stage in the attachment process.. This paper shows the results of a performance evaluation test of a particular type of the ESE air terminal (called "ElecHippo") with a simple rod tested at the Korea Electrotechnology Research Institute (KERI). The corona emission current of the ElecHippo made by Yong-Jin Enterprise Corp. has also been measured at the Occupational Safety & Health Research Institute (OSHRI). The results show that the ElecHippo meets the French standard of NFC 17-102-1995. The results also verify the ESE performance by measuring the ion emission current generated in the discharge electrode gap as a function of the capacitance and inductance of the equipped devices. Finally, we propose a new method for grounding the system to reduce the lightning damage by combining the ESE air terminal, the early discharge earth plate, the lightning strike recorder and the surge protection device.