• Earthquakes and Structures
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• 제7권3호
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• pp.365-384
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• 2014

The intensity of a ground motion can be measured by a number of parameters, some of which might exhibit robust correlations with the damage of structures subjected to that motion. In this study, 204 near-fault pulse-type records are selected and their seismic parameters are determined. Time history and damage analyses of a tested 3-storey reinforced concrete frame representing for low-rise reinforced concrete buildings subjected to those earthquake motions are performed after calibration and comparison with the available experimental results. The aim of this paper is to determine amongst several available seismic parameters, the ones that have strong correlations with the structural damage measured by a damage index and the maximum inter-story drift. The results show that Velocity Spectrum Intensity is the leading parameter demonstrating the best correlation, followed by Housner Intensity, Spectral Acceleration and Spectral Displacement. These seismic parameters are recommended as reliable parameters of near-fault pulse-type motions related to damage potential of low-rise reinforced concrete structures. The results also reaffirm that the conventional and widely used parameter of Peak Ground Acceleration does not exhibit a good correlation with the structural damage.

• 한국재난정보학회 논문집
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• 제18권1호
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• pp.19-28
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• 2022

연구목적: 전기로 인한 화재·폭발·감전 등의 재해를 예방하기 위한 방법 중의 하나가 접지를 시행하는 것이다. 접지전류가 높은 주파수 성분을 포함하는 경우에는 접지저항보다는 접지임피던스를 측정하는 것이 바람직하다. 본 연구에서는 수 kHz 이상의 주파수 성분을 가지는 접지전류에 의한 대지전위상승을 억제하기 위한 접지임피던스를 줄이는 방안을 제시하고자 한다. 연구방법: 대지에 접지동봉과 접지침봉을 매설하여 각각 접지저항과 접지임피던스를 측정하였고, 주파수에 따른 접지임피던스의 특성을 파악하였다. 연구결과: 접지동봉과 접지침봉의 접지저항 측정 결과는 거의 차이가 없었다. 62.5kHz 보다 낮은 주파수 영역에서는 접지동봉이나 접지침봉의 접지임피던스 측정 결과는 거의 차이가 없었으며, 62.5kHz 보다 높은 주파수 영역에서는 접지침봉의 접지임피던스가 접지동봉의 접지임피던스보다 약 15% 정도의 저감효과가 있었다. 결론: 상용주파수 영역에서 접지저항 값을 낮추기 위하여 다수의 접지극을 공통으로 접지하는 것이 효과적이고, 접지임피던스가 낮은 접지침봉을 설치하는 경우 수 kHz 이상의 주파수 성분을 가지는 접지전류에 의한 대지전위상승을 효과적으로 억제할 수 있을 것으로 보인다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.241-245
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• 2004

The electric safety tends to be more important according to electric facilities's increase and its use in these days. This paper analyzes soil resistivity of two areas in the country using CDEGS(Current Distribution, Electromagnetic Interference, Grounding and Soil Structure, Canada). We designed rod and mesh grounding system and made a comparative study of ground resistance, GPR(Main Electrode Potential Rin), step voltage and touch voltage. Then we could analyz only the safety but also economical efficiency in elocution of grounding. As a result of simulation, ground resistance, GPR(Main Electrode Potential Rise), step voltage and touch voltage became higher in proportion to soil resistivity. Therefore we expect to estimate the propriety of grounding system design through accumulation and analysis of data in consideration of characteristics of soil.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.71-74
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• 2003

Fall-of-potential method is used usually to measure the ground impedance of large scale grounding system exactly. Because the interlinked magnetic flux between closed loops to inject test current and to measure potential rise is existed in E-P-C straight line arrangement, mutual(or inductive) coupling influences greatly on the measurement correctness. Measurement errors produced from inductive coupling could be reduced by the arrangement methods of auxiliary electrodes. Right angle or P-E-C order arrangement methods were effective to reduce the inductive coupling and the decrease degree of measurement error was analysed as quantitative through an experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.509-511
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• 2004

Grounding rods as a discharge path are normally used to ensure the safety of human beings and facilities from the over-voltages and the over·current. Each grounding mode class 1, class 2, class 3, special class 4- has prescribed ground resistance values which are kept by the utilities. However, in the distribution system, it is very difficult for grounding rods to obtain the prescribed ground resistance values because of the limits of installation space. Therefore, in this paper, the grounding effects of the grounding copper bands which are recently developed to use efficiently in small area and the grounding rods are compared by testing the ground resistance values, ground potential rise(GPR), and step voltage in various cases.

• 조명전기설비학회논문지
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• 제20권1호
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• pp.65-70
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• 2006

본 논문은 임펄스전류에 따른 접지시스템의 과도 특성에 관한 것으로 임펄스 전류를 심매설 봉상 접지전극과 그리드 접지전극에 인가하였을 때 나타나는 과도접지임피던스를 조사하였다. 과도접지임피던스는 인가전류의 상승시간과 접지전극의 크기 및 형태에 강하게 의존하며, 접지전극의 인덕턴스는 짧은 시간 영역에서 접지시스템의 과도 접지임피던스에 크게 영향을 미치는 것으로 나타났다. 또한 심매설 봉상접지전극은 짧은 시간영역에서 과도접지임피던스를 줄이는데 효과적이었다.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.527-536
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• 2016

This paper investigates seismic damage potential of recent September 12 M5.8 Gyeongju earthquake from diverse earthquake engineering perspectives using the accelerograms recorded at three stations near the epicenter. In time domain, strong motion durations are evaluated based on the accelerograms and compared with statistical averages of the ground motions with similar magnitude, epicentral distance and soil conditions, while Fourier analysis using FFT is performed to identify damaging frequency contents contained in the earthquake. Effective peak ground accelerations are evaluated from the calculated response spectra and compared with apparent peak ground accelerations and the design spectrum in KBC 2016. All these results are used to consistently explain the reason why most of seismic damage in the earthquake was concentrated on low-rise stiff buildings but not quite significant. In order to comparatively appraise the damage potential, the constant ductility spectrum constructed from the Gyeongju earthquake is compared with that of the well-known 1940 El Centro earthquake. Deconvolution analysis by using one accelerogram speculated to be recorded at a stiff soil site is also performed to estimate the soil profile conforming to the response spectrum characteristics. Finally, response history analysis for 39- and 61-story tall buildings is performed as a case study to explain significant building vibration felt on the upper floors of some tall buildings in Busan area during the Gyeongju earthquake. Seismic design and retrofit implications of M5.8 Gyeongju earthquake are summarized for further research efforts and improvements of relevant practice.

• 조명전기설비학회논문지
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• 제21권10호
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• pp.181-189
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• 2007

본 논문에서는 전기철도에서 발생하는 대지전위와 통신회선의 잡음에 대한 실험적 증명에 관한 것이다. 대지전위차가 발생하는 곳에서 전력유도잡음전압과 케이블 평형도 등을 측정할 경우 계측 오차가 심각하게 발생되는 것으로 나타났다. 측정결과, 고속철도 인접한 곳의 통신케이블은 시스층에 지전류가 많이 흐르는 차폐 케이블보다 일반 케이블을 그대로 사용하는 것이 잡음피해를 보다 줄일 수 있음이 실험 결과로 확인 되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 전기설비전문위원
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• pp.6-9
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• 2009

Recently, there have been studied the importance of the grounding system, as electrical equipments installed in the building, such as intelligent building. The object of grounding of electrical facilities is to protect human and machine damage from the power supply interruption high voltage by use of the accident current dissipating into the ground. In this paper, we is proposed to design of grounding system with economical efficiency in electric rolling stocks facilities. To make efficient ground, ground potential rise must be controlled in the way of overall lowering and evenness instead of independent grounding method with respect to electrical facilities.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.69-72
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• 2008

This paper presents the transient and conventional grounding impedance behaviors of large grid grounding system associated with the injection point of impulse current The measurement methods consider two possible errors in the grounding-system impedances: (1) ground mutual resistance due to current flow through ground from the ground electrode to be measured to the current auxiliary, (2) ac mutual coupling between the current test lead and the potential test lead The test circuit was set to reduce the error factors. The transient grounding impedance depends on the rise time and injection point of impulse current It is effective that grounding conductor is connected to the center of the large grid grounding system.