• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.477-482
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• 2011

In the present study, the diffusion process of hydrogen leaking from a FCV (Fuel Cell Vehicle) in an underground parking lot was analyzed by numerical simulations in order to assess the risk of a leakage accident. The temporal and spatial changes of the hydrogen concentration as well as the flammable region in the parking lot were predicted numerically. The effects of the leakage flow rate and an additional ventilation fan were investigated to evaluate the ventilation performance in the parking lot to relieve the accumulation of the leaked hydrogen gas. The present numerical analysis can provide useful information such as the distribution of the leaked hydrogen concentration for safety of various hydrogen applications.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.125-137
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• 2019

The purpose of this paper is to study the source term behavior after severe accidents by using a semi-kinetic model for simulation and calculation of in-containment activity. The reactor containment specification and the safety features of the containment under different accident conditions play a great role in evaluating the in-containment activity. Assuming in-vessel and instantaneous release of radioactivity into the containment, the behavior of in-containment isotopic activity is studied for noble gasses (Kr and Xe) and the more volatile elements of iodine, cesium, and aerosols such as Te, Rb and Sr as illustrative examples of source term release under LOCA conditions. The results of the activity removal mechanisms indicates that the impact of volumetric leakage rate for noble gasses is important during the accident, while the influence of deposition on the containment surfaces for cesium, mainly iodine isotopes and aerosol has the largest contribution in removal of activity during evolution of the accident.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.51-54
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• 2009

Total monitoring device of leakage current in transformer can detects the flowing leakage current on the ground wire connected with the neutral point, and that is monitored at real-time by the transfer. If the over-flowing current is detected, Total monitoring device of leakage current in transformer will warn the administrator to prevent electrical accident. In this thesis, we are going to explain about Total monitoring device of leakage current in transformer. Also we measure leakage current and judge safety in customer.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1082-1084
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• 1998

In this paper, we developed a diagnosis device for ZnO arrester to detect on-line leakage current and acquire data from the power distribution system. The arrester is important power equipment used in power transmission and distribution systems to protect the generator and the main transformer from surge and overvoltage. First of all we developed a diagnosis device for ZnO arrester leakage current. And then we detect the total leakage current by the developed device without disconnecting the arrester ground wire and analysis the 3rd order harmonic by Fast Fourier Transform(FFT) to diagnose the ZnO arrester deterioration. With measuring the total current and the resistive current of power distribution system in operation, we analysis the trend of resistive current component in the total leakage current. We expect the result will be promote the method to protect electrical utility and customer from accident.

• Convergence Security Journal
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• v.15 no.7
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• pp.39-45
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• 2015

Industrial secrets that companies own recently protected by various act related industrial security such as Trade Secret Act, Act on Prevention of Divulgence and Protection of Industrial Technology, etc. However, despite such protection infringement and leakage accidents of industrial secrets is increasing every year. According to a survey conducted by KAITS(Korean Association for Industrial Technology Security) annual average of estimated damage by industrial secrets leakage is estimated to be "50 trillion won." This is equivalent to the amount of annual revenue of small businesses more than 4,700 units. Following this, industrial secrets leakage causes serious damages to competitiveness of nation and companies and economic. However investment and effort to the industrial secrets leakage crime is lack of level compared to the scale of damage. Actually, most companies except some major companies are lack of response action about industrial secrets leakage because of shortage of separate organization, workforce, budget for industrial secrets leakage security. This paper aims to understand the overall flow of the industrial secrets leakage crime through various taxonomy such as cause of occurrence and leakage pathway and grasp the condition of damage from industrial secrets leakage through analyzation of internal and external industrial secrets leakage crime. This is expected to be the basis for related research.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.28-33
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• 2009

This study examined the mounting status of cigar lighter receptacles for vehicles and analyzed the tracking phenomenon that occurs when foreign material entered a cigar lighter receptacle to obtain data for the analysis of accident investigation. Regardless of the vehicle's output, cigar lighter receptacles are mounted in a vehicle horizontally, vertically, or at tilting or inclined angle. The tilting type cigar lighter receptacle is much easier to use but current leakage resulting from foreign materials (coffee, beverages, water, etc.) falling into the cigar lighter receptacle may cause a fire to start. This study used a vehicle battery (DC 12V) as a power supply for the tracking test and configured its circuit in the same way as that of an electrical device in a vehicle. The tracking phenomenon that occurred in the standby mode of the vehicle exhibited a fine flame and an irregular occurrence of smoke. While this tracking phenomenon was occurring, the leakage current and the reaching distance of the flame were measured to be approximately 930mA and $20{\sim}50cm$, respectively. It is thought that the resultant flame may ignite toluene, dust, cigarettes, etc. It was observed that as the tracking progressed, the internal metal socket melted and a hole was created, the surface of which was also severely carbonized. In addition, the electrical resistance of the carbonized conductive path was measured to be approximately $30{\Omega}$. It is thought that this much resistance may cause local heating when leakage current flows and could ignite any nearby flammable material.

• Fire Science and Engineering
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• v.25 no.6
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• pp.136-145
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• 2011

One of a large proportion among the causes of fire is electrical factors, and of fire by electric factors, the accident which accounted for over certain percentage is electric leakage and ground fault. In order to reduce the electric leakage and ground fault, the technical guidelines on the protection of ground fault in the low-voltage electrical line (KECG 1091-2011) was amended for reflecting recent international standard, IEC 60364-4-41, and new conservation methods, which improved the reliability by recovering the facility's all-time use operation and breakdown defect, was on the rise. Accordingly, in this paper, after grasping the fire's status for last 10 years and analyzing the risk of electrical fires, and as a way to improve the electric leakage and ground fault accident which accounted for more than certain percentage, the revision of KECG 1091-2011 will be reviewed. And then, after applying to the preventive conservation methods in order to enhance the protection reliability of electric leakage and ground fault detection, the problems at issue routine inspection scheme and durable years scheme in time-scheduled conservation method are listed, along with suggestion of the problem-solving scheme, and the leakage current integrated monitoring systems and digital electric leakage devices by status monitor conservation method will be proposed.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.213-221
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• 2024

Purpose: The purpose is to find the optimal way to quickly block the leak in the event of a leak accident in a tank lorry transporting hydrochloric acid aqueous solution, a hazardous chemical, and to carry out effective disaster prevention work to minimize damage caused by the leak. Method: We organized the overall characteristics of hydrochloric acid and accidents that occurred during transportation by accident type and cause, and created a small tank that can be tested assuming a leak situation in a hydrochloric acid tanker, creating an environment similar to the leak situation, and leaking in various ways. I would like to experiment and organize blocking methods. Result: Through experiments, an effective leak blocking method was confirmed. We would like to summarize measures to quickly block a leak in the event of a leak and present the optimal disaster prevention plan that can be applied at the accident site. Conclusion: It has been confirmed that using a combination of adhesive tape and magnets is more effective in blocking leaks. Rapid response is possible by repeatedly training business emergency response teams and product transporters to appropriately select and respond to leak-blocking equipment. Additional research on various leak prevention methods is needed in the future.

• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.11-25
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• 2015

The accident at Japan's Fukushima Daiichi nuclear power plant in March 2011, caused by an earthquake and a subsequent tsunami, resulted in a failure of the power systems that are needed to cool the reactors at the plant. The accident progression in the absence of heat removal systems caused Units 1-3 to undergo fuel melting. Containment pressurization and hydrogen explosions ultimately resulted in the escape of radioactivity from reactor containments into the atmosphere and ocean. Problems in containment venting operation, leakage from primary containment boundary to the reactor building, improper functioning of standby gas treatment system (SGTS), unmitigated hydrogen accumulation in the reactor building were identified as some of the reasons those added-up in the severity of the accident. The Fukushima accident not only initiated worldwide demand for installation of adequate control and mitigation measures to minimize the potential source term to the environment but also advocated assessment of the existing mitigation systems performance behavior under a wide range of postulated accident scenarios. The uncertainty in estimating the released fraction of the radionuclides due to the Fukushima accident also underlined the need for comprehensive understanding of fission product behavior as a function of the thermal hydraulic conditions and the type of gaseous, aqueous, and solid materials available for interaction, e.g., gas components, decontamination paint, aerosols, and water pools. In the light of the Fukushima accident, additional experimental needs identified for hydrogen and fission product issues need to be investigated in an integrated and optimized way. Additionally, as more and more passive safety systems, such as passive autocatalytic recombiners and filtered containment venting systems are being retrofitted in current reactors and also planned for future reactors, identified hydrogen and fission product issues will need to be coupled with the operation of passive safety systems in phenomena oriented and coupled effects experiments. In the present paper, potential hydrogen and fission product issues raised by the Fukushima accident are discussed. The discussion focuses on hydrogen and fission product behavior inside nuclear power plant containments under severe accident conditions. The relevant experimental investigations conducted in the technical scale containment THAI (thermal hydraulics, hydrogen, aerosols, and iodine) test facility (9.2 m high, 3.2 m in diameter, and $60m^3$ volume) are discussed in the light of the Fukushima accident.

• Fire Science and Engineering
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• v.31 no.1
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• pp.81-88
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• 2017

This study analyzed chemical accidents each year according to the status, type of accident, accident place, business size, and chemical substance. The results of the chemical accident investigation were 16 cases in 2013, 27 cases in 2014, 46 cases in 2015, and 23 cases in 2016. According to the type of chemical accident, number of accidents, and casualty accidents, leakage was found to be the major cause. As a result of accidents and casualties caused by chemical accidents, workplaces had the highest numbers in all survey items. An examination of the top 10 accident materials revealed 9 substances to be hazardous chemicals. These materials were accident preparedness substances, and toxic substances.