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- 저자 : 서재석(Jae-Suk Seo) (검색결과 6 건)
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서재석,박희철,길경석,오재근,Seo, Jae-Suk,Park, Hee-Chul,Kil, Gyung-Suk,Oh, Jae-Geun 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.6
This paper carried out the comparative analysis on ground impedance of a carbon block and a copper rod. Two types of grounding electrode were compared ; a carbon block (L : 1 m, ${\Phi}$ : 245 mm) buried at a depth of 0.8 m and a three-linked copper rod (L : 1 m, ${\Phi}$ : 10 mm) of equilateral triangles with 1 m spacing. Ground impedance depending on applied current source was evaluated by the application of a sine wave current with 60 Hz ~ 3.5 MHz, a fast-rise pulse with rising time of 200 ns, a standard lightning impulse of $8/20{\mu}s$ and a 600 Hz square wave. Ground impedance for both electrodes were almost the same value below 100 kHz, and increased rapidly afterwards. The maximum ground impedance appeared $400{\Omega}$ at around 1.5 MHz. Ground impedance of the carbon block was lower at the square wave and was higher at fast-rise pulse than that of the copper rod. Also, ground impedance as ages showed no difference for the last 8 months. From the results, it is likely that ground performance for both electrodes shows no difference against commercial frequency and lightning impulse current, while the copper rod shows better performance against a fast-rise pulse with rise-time of a few hundred ns.
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서재석(Jae-Suk Seo),이정윤(Jung-Yoon Lee),진창환(Chang-Hwan Jin),길경석(Gyung-Suk Kil) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.5
본 논문에서는 탄소블록과 동봉의 접지성능을 분석하였다. 0.8 [m] 깊이에 매설된 두 가지 형태 즉, 전극간 거리를 1 [m]로 하여 정삼각형의 3연접 동봉과 탄소블록을 비교하였다. 접지임피던스는 IEEE Std. 81.2에 제시된 전위강하법으로 측정하였으며, 인가전류와 전압의 최대값의 비로 산출하였다. 접지극에는 500 [ns]의 상승시간을 갖는 스텝펄스, 8/20 [μs]의 표준 뇌임펄스 및 1 [kHz] 구형파 펄스를 인가하였다. 7개월간 주기적으로 접지임피던스를 측정하였으며, 경년에 따라 탄소블록과 3연접 동봉에서 모두 증가하는 경향을 나타내었다. 또한 8/20 [μs]와 구형파 전원에 대한 접지임피던스는 3연접 접지동봉에서 높게 나타났다. This paper describes an analysis on grounding performance for a carbon block and a cooper rod. Two types of grounding systems buried at a depth of 0.8 [m] were compared; a three linked copperelectrodes of equilateral triangles with 1 [m] spacing and a carbon-electrode. The ground impedances were measured using the fall-of-potential method specified in IEEE Std. 81.2 and were calculated as the ratio of the peak potential rise to the peak injection current at same time. Applied current to the grounding system was a step pulse with a rising time of 500 [ns], a standard lightning impulse of 8/20 [μs] and a square waveform pulse of 1 [kHz]. We carried out a periodic measurement for seven months. Ground impedance for both increased with ages. Also, ground impedance of the three linked copper-electrodes was higher than that of carbon block to the 8/20 [μs] impulse and the square waveform pulse source.
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이영근(Young-Keun Lee),서재석(Jae-Suk Seo),문병두(Byung-Doo Moon),박희철(Hee-Chul Park) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
The importance of modern electronic devices is gradually increased and, the requirement of the safe and reliable earthing and bonding for protection of the electronic devices is consequently absolute. The electrical continuity and physical strength of the bonding work in rail signal and impedance bonding is also one of the important issues. The thermit welding for earth cable connection and rail bonding work proposed hereunder is an effectively applicable in many fields of rail industries.
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진창환(Chang-Hwan Jin),박대원(Dae-Won Park),길경석(Gyung-Suk Kil),서재석(Jae-Suk Seo) 한국철도학회 2012 한국철도학회 학술발표대회논문집 Vol.2012 No.10
본 논문에서는 동봉과 탄소접지극을 매설하여 저주파수 구형파, 표준 뇌임펄스 및 급준파 펄스에 따른 접지임피던스 응답특성에 대하여 기술하였다. 접지임피던스의 측정은 IEEE Std. 81.2에서 규정하고 있는 전위강하법을 적용하였으며, 인가전류에 따른 전위상승을 측정함으로써 임피던스를 산출하였다. 1 [m] 간격의 정삼각형으로 배치한 3연접 동봉과 0.8 [m] 깊이에 매설한 탄소접지극을 사용하여 실험을 수행하였다. 실험 결과, 접지임피던스는 주파수에 비례하는 특성이 나타났으며, 고주파수 영역에서는 3연접 동봉이 탄소접지극에 비해 더 낮은 임피던스 응답특성을 보였다. This paper describes the ground impedance on copper- and carbon-electrode by the application of a low frequency square waveform, a standard lightning impulse, and a fast-rise step pulse. The ground impedances were measured using the fall-of-potential method specified in IEEE Std. 81. 2. and were calculated as the ratio of the peak potential rise to the peak injection current at same time. Two types of grounding systems buried at a depth of 0.8 [m] were compared ; a three linked copperelectrodes of equilateral triangles with 1 [m] spacing and a carbon-electrode. Experimental results showed that the ground impedances increased with the applied frequency, and the three linked copper-electrodes had a lower impedance compared to the carbon-electrode in high frequency range.
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진창환(Chang-Hwan Jin),박대원(Dae-Won Park),서재석(Jae-Seok Seo),길경석(Gyung-Suk Kil),길형준(Hyeong-Jun Gil) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
In measurement of risk voltages; the step and touch voltage the distance between the current electrode and the ground electrode recedes up to several hundred meters as the scale of grounding system increases. This paper dealt with the measurement method of risk voltage in a restricted space. The risk voltage was analyzed depending on the distance and the direction of the current electrode from the ground electrode in a 10 [m] * 10 [m] mesh grounding system. The average value of risk voltages measured at a point 20 [m] away from the current electrode was deviated below 5 [%] from that measured at 100 [m] point. Consequently the evaluation of risk voltage of a large-scale grounding system buried in a spatially restricted place is available if the current electrode is installed in symmetry to the ground electrode.
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