• International Journal of Safety
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• 제8권2호
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• pp.9-14
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• 2009

This paper describes analysis of risk voltage for grounding electrode where earth leakage current is injected. To assess risk voltage of grounding electrode, the grounding simulator and CDEGS program were used to obtain measured data and theoretical results of this study. The grounding simulator was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The shapes of grounding electrode model was ground rod. The potential rise was measured by grounding simulator, and the touch and step voltages were computed by CDEGS program. As a consequence, the potential rise of ground rod abruptly decreases with increasing the distance from the grounding electrode to the point to be tested. The touch voltage above the ground rod was low, but the step voltage was high. The measured results were compared with the computer calculated data and were known in good agreement.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술.기술논문발표회
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• pp.105-108
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• 2004

The most of former schools facility have been planed and constructed with cement liquid waterproofing which is moth to be desired fir behavior of structure. However. It cause to decline safety for structure and also increase repairing cost that by leakage to behavior for thermal effects, Moreover, It is necessary for establishment fundamental counterplan of maintenance for schools facility to improve educational environment in budget support and proper diagnostic tech. and evaluation, repair reinforcement. In present paper, Firstly, we analyze out leakage and defect of schools facility of ㅇㅇ district office of education. Secondly, suggest the proper diagnostic tech. as leakage factor to develope efficiency of using space for durability and safety from leakage with suggestion the proper diagnostic.

• 한국안전학회지
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• 제27권6호
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• pp.48-53
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• 2012

This paper is purposed to develop portable electric instrument to select NI-9223(National instrument comp.) and clamp meter(HIOKI comp.), which can be used in developing electric instrument, to detect leakage current(ZCT) and current(CT) signals. In this paper, The electric instrument that can interface with current and leakage current instrument(HIOKI 9283), is developed by NI-9223 of NI comp.. HIOKI clamp meter can measure current signals certainly by high-sensitivity of 10 ${\mu}A$ resolution(leakage current : at 10 mA range) and current 1~200A range. The NI-9223 use four 16-bit analog-to-digital converters(ADCs) for true simultaneous sampling at up to 1 MS/s per channel. NI-9223 can synchronize all analog input modules installed in the same chassis to share the same start clock and/or sample clocks. The monitoring program is developed by SignalExpress of LabVIEW. The monitoring program are developed to analyze at simultaneous sampling on electrical signals such as leakage current(ZCT) and current(CT). The developed system verification tests were conducted, and portable electric instrument can be used in place which requires analysis of the actual electrical signal.

• 전기학회논문지
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• 제63권6호
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• pp.828-833
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• 2014

Grid connected transformerless solar power generation system is frequently used with the benefits of cost and efficiency. However, significant DC leakage current can flow from the DC line into the ground with dielectric breakdown in the transformerless solar power generation system. The leakage current occurred in the DC line causes accidents such as fire and electric shock on human. To resolve this problem, high sensitivity DC leakage current sensor is needed. But recently the studies on safety of DC line are not performed. In this paper, a high sensitivity DC leakage current sensor that can detect DC leakage current in solar power generation system, is proposed. Based on the studies, DC leakage current sensor is fabricated and characteristic tests are carried out. Finally, the accuracy of sensor performance is verified by leakage current experiments in solar power generation system.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.378-383
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• 2009

Hydrogen is the primary fuel in fuel cell systems. Because of high inflammation and explosion possibility of hydrogen, fuel cell systems require safety measures to prevent hydrogen hazard upon leakage. In this study, a model enclosure was made by referring to a commercial residential fuel cell system and hydrogen leakage experiments and computational simulations were conducted therein. Hydrogen was injected into the cavity through leakage holes located at the bottom while its flow rate was precisely controlled using MFC. The transient sensor signals from hydrogen sensors installed inside the enclosure were recorded and analyzed. The hydrogen sensor signals showed different delay times depending on their position relative to a leakage point, which indicated that hydrogen generally moves upward and accumulates at the upper region of a closed cavity. The inflammable regions with hydrogen concentration over 4% LEL were observed to locate near the leakage hole initially, and broaden towards the upper cavity region afterward. The simulation result showed that detection time at the hydrogen sensor was similar to the pattern of experimental results. However, the maximum concentration of hydrogen had a gap between experiment and simulation at detect point due to measurement errors and reaction rate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 전기설비
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• pp.25-26
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• 2006

An electrical fault is defined as any abnormal condition caused by reduction in the insulation strength between energized conduction parts and ground or any grounded part of an electrical system. Failure of solid insulation can be caused by excessive mechanical tension being applied on the insulation, harsh service environment, aging, and also by corona phenomena. The number of empty houses during normal working hours is rising. As a result, the number of uninspected electric installation for general use is increasing. To define the potential risk of the electric installation, measurement of leakage current has been getting considered, but because the measured leakage current value also contained leakage current by capacitance, the measured value can not be adapted to absolute reference to the installation. Therefore, in this paper, the correlation between the condition of electric installation and leakage current were analyzed.

• 한국지반환경공학회 논문집
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• 제11권9호
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• pp.15-25
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• 2010

본 연구는 중앙심벽형 필댐인 주암댐과 임하댐을 대상으로 자동계측에 의해 연속적으로 생산되는 침투수량 계측자료에 대하여 분석을 통하여 필댐 고유의 특성에 따른 장기 침투특성과 댐의 안전관리 방법을 검토하고자 하였다. 필댐의 침투수량 계측값에는 내재 하는 강우 성분 등의 외부 요인의 영향으로 직접적으로 이상 누수의 발생을 검출하는 것은 어렵다. 이 때문에, 종래 저수위와 강우량을 고려하는 중회귀분석 등에 의해 누수량을 추정하는 방법이 적용되어 왔으나, 강우 성분의 추정 오차가 상대적으로 크고 정밀도가 불량한 것으로 알려졌다. 본 논문에서는 강우 성분의 분리해석을 통해 직접적으로 강우 성분에 영향을 받지 않는 저수지 수위에 연동하는 댐별 침투거동을 평가함과 아울러 분석대상 댐의 지형적, 수리지질학적 특성을 반영한 3차원 수치해석을 실시하여 계측 침투수량 자료와 비교하였다. 2개 대상댐의 침투거동은 각각의 고유한 특징을 가지고 있으며, 장기적으로 침투수량의 감소를 보여주고 있어 안정적인 상태로 나타났다. 또한, 수문곡선분리법은 침투수 안전관리 방법으로 적용가능한 것으로 판단되었다.

• 한국가스학회지
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• 제22권3호
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• pp.38-44
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• 2018

암모니아는 발전소의 탈질설비, 냉동장치의 냉매로 많이 사용되고 있으며, 증기압이 높고 공기보다 가벼운 물질로써 장외영향평가시 영향범위가 넓은 물질이다. KORA(Korea Off-site Risk Assessment supporting tool)를 활용하여 4가지 환경인자인 지면굴곡도, 밀폐여부, 운전온도 압력, 누출공 크기를 달리하여 영향범위를 산출하였다. 그 결과 굴곡도에 따른 영향범위는 약 4.62배 차이가 났으며 암모니아 저장탱크는 밀폐된 경우가 약 0.64의 저감율을 나타냈다. 저장온도와 압력에 따라 누출률이 증가되어 영향범위도 증가하는 형태를 보였으며 포화증기압 이상으로 저장시 영향범위는 $45^{\circ}C$에서 0.1 Mpa 당 평균 3.45%의 증가율을 나타냈다. 누출공 크기에 따른 영향범위 산정 결과는 누출구의 면적에 비례하는 것으로 나타났다.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1998년도 추계 학술논문발표회 논문집
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• pp.335-340
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• 1998

This paper presents a study on the electrical fire hazards of leakage current in a distribution circuit simulating a domestic circuit for low voltage. In this simulated circuits, total charges and energy of leakage current are calculated by a theoretical approach and compared with the results obtained from experiments, The approach and results become a cornerstone for studying and analyzing causes of electrical fires.

• 대한안전경영과학회지
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• 제3권4호
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• pp.45-52
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• 2001

In order to Investigate water tree degradation behavior on XLPE cable, direct voltage of 200 to 800V has been applied to the material at 5$0^{\circ}C$~10$0^{\circ}C$, and the water tree property has been correlated with voltage and temperature. The leakage current was increase as temperature increased and the Ohm's law was generally satisfied in this experiment though some experimental errors were found. The leakage current was decreased and reached to the stable state with time. It was also shown that the time for the stabilization of leakage current was lessened as voltage increased