• Proceedings of the KSR Conference
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• 2008.11b
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• pp.241-247
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• 2008

This paper describes a cause of fire accidents on power system for DC electric traction vehicles. We investigated fire scene of power line for DC electric traction vehicles. From analysis results, the cause of fire on power line turned out line to ground fault between a feeder of electric power services(pantagraph) and DC electric traction vehicle roof. Fire accidents of DC electric traction vehicles be assumed that electric sparks had been produced between the pantagraph and the power line conductor by repetitively making contact and separation, maybe if some material like branches get in between connecting rod it make progress line to ground fault. ZnO arresters are widely used to protect DC electric traction vehicles against overvoltages caused by lightning or switching surges. However, the arresters are deteriorated by commercial frequency overvoltages and/or lightning one. Deteriorated arresters could lead power failures, such as line to ground fault by a thermal runaway resulting from the increases in leakage current even in a nominal power system voltage. The power failures, such as line to ground fault would be causative of the fire accidents.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.16-21
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• 2017

Fire or electrical problem while DC electric traction vehicle operation caused by various reasons can lead to not only suspension of the operation, but also severe aftermath such as massive casualty. In this paper, fire analysis on DC electric traction vehicle caused by electrical breakdown on line breaker, which is in connection with the power supply, is presented. When the electric arc, the by-product of frequent line breaker operation, is not fully diminished, it leads to electrical breakdown and fire. Especially, electrical breakdown can be easily induced by the open-and-close operation of inner contractor inside line breaker, eventually followed by ground fault and generation of transient current. Electric arc is consequent on the ground fault and acts as possible ignition source, leading to fire. Also, during the repetitive operation of the line breaker, the contactor is separated each other and some copper powder is generated, and the copper powder provided breakdown path, resulting in fire.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.71-81
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• 2005

The main objective of the present study is to investigate the performance characteristics of a ground-source heat pump(GSHP) system with a 130 m vertical and 62 mm nominal diameter U-tube ground heat exchanger. In order to evaluate the performance analysis, the ground-source heat pump connected to a test room with $90\;m^2$ floor area in the Korea Institute of Construction $Technology(37^{\circ}39'N,\;126^{\circ}48'E)$ was designed and constructed. This ground-source heat pump system mainly consisted of ground heat exchanger, indoor heat pumps and measuring devices. The cooling and heating loads of the test room were 5.5 and 7.2 kW at design conditions, respectively. The experimental results were obtained from July 2, 2003 to July 1, 2004. The cooling and heating performance coefficients of the system were determined from the measured data. The average cooling and heating COPs for the system were obtained to be 4.90 and 3.96, respectively. The temperature variations in ground and the ground heat exchanger pipe surface at different depths were also measured.

• International Journal of High-Rise Buildings
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• v.2 no.4
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• pp.341-344
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• 2013

During a building fire, smoke can flow through elevator shafts threatening life on floors remote from the fire. Many buildings have pressurized elevators intended to prevent such smoke flow. The computer program, CONTAM, can be used to analyze the performance of pressurization smoke control systems. The design of pressurized elevators can be challenging for the following reasons: (1) often the building envelope is not capable of effectively handling the large airflow resulting from elevator pressurization, (2) open elevator doors on the ground floor tend to increase the flow from the elevator shaft at the ground floor, and (3) open exterior doors on the ground floor can cause excessive pressure differences across the elevator shaft at the ground floor. To meet these challenges, the following systems have been developed: (1) exterior vent (EV) system, (2) floor exhaust (FE) system, and ground floor lobby (GFL) system.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.41-45
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• 2007

Short circuit and ground fault account for the primary causes of electrical fires. In this research, real-scale experiments were conducted to assess the possibility of electrical fires due to these causes. The experiment conditions were identical with an actual fire accident, in which the power cable was supported by an iron fence. The purposes of this research are to investigate the short circuit caused by wire cutting, the conductivity of the iron fence depending on its coating conditions, and the ground fault of one wire or two wires in an effort to reconstruct the fire accident. The test results show that, owing to the instant operation of circuit breaker in the moment of short circuit or ground fault, the generated ignition energy is far less than necessary to start an ignition. Therefore it is concluded that electrical fire is highly unlikely if the electric system is protected by a circuit breaker with normal functions.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.20-25
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• 2011

The fire event occurred in fire proof zone often causes serious electrical problems such as shorts, ground faults, or open circuits in nuclear power plants. These would be directed to the loss of safe shutdown capabilities performed by safety related systems and equipments. The fire event can treat the basic design principle that safety systems should keep their functions with redundancy and independency. In case of a multi-core cable fire, operators can not perform their mission properly and can misjudge the situation because of spurious operation, wrong indication or instrument. These would deteriorate the plant capabilities of safety shutdown and make disastrous conditions. In this paper, the characteristic of cable fire is investigated and the heat-flux evaluation for cable fire is studied. Moreover, a diagnostic methodology for degraded cable in nuclear power plants is presented.

• Fire Science and Engineering
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• v.25 no.1
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• pp.50-56
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• 2011

In recently years, occurrences of lightning return strokes have been increased by global worming effect and intensity of lightning impulse voltage and current accompanied by lightning discharges has being strengthening. In Korea, 560 thousand lightning discharges happened in 200S. According to the increasing frequencies of lightning, human deaths and damages to the structure have been increased steadily. Electric fire caused by lightning return strokes due to the breakdown between power line and ground line from the ground potential rise on a process of the lightning impulse current through to the ground. The damages of lightning were occurring at same time in the neighboring areas of the lightning point. In order to protect from the lightning stroke, we made a suggestion to use protection devices and equipotential bonding at the dangerous areas. The analysis results of electric fires caused by lightning would be utilized to investigate and to find accurate fire cause in the fire scenes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.10
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• pp.21-29
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• 2013

The short circuit and overload is presented by main cause of electrical fire. However, 85% of the fan directly connected the outlet box without switch in total 110 fans as a research in manufacturing industries. In installation direction of vertical type fans which was placed on the horizontal surface, only 39 vertical type fans were placed on vertical surface and 71 fans were placed on the horizontal type. The installation direction of the fans warns of the risk of the fire hazard due to the motor stall to the user manual of the maker. However, it is the representative nonconformity example of construction which the people or builder disregards. In addition, the condition of ground connection with the earth leakage prevention was investigated in grounding of 5 fans, non-grounding of 105 fans. The double insulation structure is generally used for small fan and it can't connect ground wire as electric plug of non-grounding type. However, industrial iron fan needs ground wire for electric leakage and to protect against electric shock.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.351-361
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• 2010

The primary purposes for using fire are to enhance marsh vegetation to support waterfowl, and to manage invasive plant species. The study was conducted for two consecutive years in 2004 and 2005, investigating the effects of prescribed fire regimes on vegetation biomass in tidal brackish marsh areas of the Blackwater National Wildlife Refuge located on the eastern shore of Maryland, USA, that are under relatively similar environmental conditions. Four different burn regimes (i.e., annual burn, 3-5 year burn, 7-10 year burn, and no burn) were applied in the study. Above- and below-ground vegetation biomass samples as affected by the different burn regimes were harvested in each year for five plant species native to the marsh; Distichlis spicata, Spartina alterniflora, Schoenoplectus americanus, Spartina cynosuroides and Spartina patens. No significant difference was found either in total above-ground biomass or in above-ground biomass by species between burn regimes in 2004. However, more total above-ground biomass was produced in annual burn regime in 2005 than in the other burn regimes. There were no consistent effects of burning on vegetative biomass production by species, but it seemed D. spicata was somewhat benefited by prescribed burning for its biomass production. Moreover, the stem density for D. spicata under annual burn regime was significantly higher than that in the other burn regimes, showing some positive effects of burning on vegetation. The below-ground biomass was significantly greater in 2004 than in 2005, yet with no significant difference between burn regimes in either year. A longer-term monitoring is strongly recommended.

• Earthquakes and Structures
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• v.10 no.4
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• pp.867-891
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• 2016

This paper addresses numerically the behavior of steel structures under Fire-after-Earthquake (FAE) loading. The study is focused on a four-storey library building and takes into account the damage that is induced in structural members due to earthquake. The basic objective is the assessment of both the fire-behavior and the fire-resistance of the structure in the case where the structure is damaged due to earthquake. The combined FAE scenarios involve two different stages: during the first stage, the structure is subjected to the ground motion record, while in the second stage the fire occurs. Different time-acceleration records are examined, each scaled to multiple levels of the Peak Ground Acceleration (PGA) in order to represent more severe earthquakes with lower probability of occurrence. In order to study in a systematic manner the behavior of the structure for the various FAE scenarios, a two-dimensional beam finite element model is developed, using the non-linear finite element analysis code MSC-MARC. The fire resistance of the structure is determined using rotational limits based on the ductility of structural members that are subjected to fire. These limits are temperature dependent and take into account the level of the structural damage at the end of the earthquake and the effect of geometric initial imperfections of structural members.