• Journal of Korean Society for Quality Management
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• v.43 no.3
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• pp.327-340
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• 2015

Purpose : Recently, many quality issues are aroused in military forces, such as failures in K-series weapons, combat uniforms' defects and 40mm ammunition explosion accident. To address these problems, Defense Agency for Technology and Quality(DTaQ) introduced new systems such as Manufacturing Readiness Assessment(MRA), Test Report Information System(TRIS) and so on. However, these activities require the human and time resources which cannot be increased in short period. In this paper, we suggest more practical and efficient product examination method. Methods : The most popular and widely used government's quality assurance technique is a sampling method to examine the product. In this research, we first reviewed the DTaQ's quality assurance regulation, then identified several possible problems and finally suggested more efficient and effective sampling plans. Results : We have suggested new sampling framework and evaluated its performance on two military supplies by comparing with other sampling method, and observed that the number of tested samples can be substantially reduced. Therefore, required quality assurance time can be saved. Conclusion : In this paper, we first reviewed the product examination frameworks of DTaQ, PPQMS and DCMA. Then we identified several possible problems which can cause the loss of objectivity and time. To handle these problems, we suggested the new product examination framework and tested the framework to verify the performance.

• Fire Science and Engineering
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• v.31 no.6
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• pp.112-117
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• 2017

This research discusses the correlation about fire mechanism based on real fire cases. Electric power condenser failure mechanism is classified into 7 steps and fire mechanism is classified into 12 steps. In the 5th step, the procedure of operating a protection channel of a protection relay was identical in the case of the failure and fire. As the fire occurrence mechanism was applied from the 6th step, internal pressure was increased because of gas generation produced by internal combustion phenomenon and arc. This caused explosion in 10st step of fire occurrence mechanism. In 11th step, the flame such as arc gushed out with insulating oil which caused fire and leaded to second accident. This kind of step correlation could play an important part to examine fire.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.1
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• pp.11-17
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• 2000

GIS is the system that has ability of integrating, managing, and analyzing the voluminous graphic and text data, which is adequate system to manage complex network of the underground utilities of urban area. A development of gas line safety management system is accomplished to construct a database of gas line network and topographic data, create safety managing model, and estimate openly its safety by GIS. This system is designed to evaluate easily the damaged facilities in case of gas line explosion by the establishment of the geographic output system. It is designed to trace and present efficiently closed valves and interrupted facilities of gas when gas line breakage occurs, and offer the information by which one can take quickly emergency. And also, it is constructed to prevent from accident occurring under construction work by showing underground utilities and states of work.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.330-336
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• 2012

FCEV uses 250 ~ 450 V instead of using 12 V battery. High voltage vehicle can cause electric shock, fire and explosion accident. Therefore, it has potential factors that can cause hazard of safety for users. United states of America and Europe legislate regulations such as ECE R100, FMVSS 305 for regulating electrical safety during driving or after collision. The company manufacturing high voltage components must do advanced R&D about Method for improving and confirming the safety of high voltage. We develop the specific hardware components of high voltage wiring system for the power train system and power supply system of Hyundai Motors FCEV. This paper shows test method of insulative performance for securing the electrical safety of high voltage components such as power cable, connectors and buss-bar, and proposals the guide line value for human safety of FCEV according to the test result of our development components.

• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.218-227
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• 2016

Background: Steam explosions may occur in nuclear power plants by molten fuel-coolant interactions when the external reactor vessel cooling strategy fails. Since this phenomenon can threaten structural barriers as well as major components, extensive integrity assessment research is necessary to ensure their safety. Method: In this study, the influence of yield criteria was investigated to predict the failure of a reactor cavity under a typical postulated condition through detailed parametric finite element analyses. Further analyses using a geometrically simplified equivalent model with homogeneous concrete properties were also performed to examine its effectiveness as an alternative to the detailed reinforcement concrete model. Results: By comparing finite element analysis results such as cracking, crushing, stresses, and displacements, the Willam-Warnke model was derived for practical use, and failure criteria applicable to the reactor cavity under the severe accident condition were discussed. Conclusion: It was proved that the reactor cavity sustained its intended function as a barrier to avoid release of radioactive materials, irrespective of the different yield criteria that were adopted. In addition, from a conservative viewpoint, it seems possible to employ the simplified equivalent model to determine the damage extent and weakest points during the preliminary evaluation stage.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.302-310
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• 2016

An underground ammunition facility requires less quantity distances than the aboveground counterpart. However, chamber blast doors which resist the high blast-pressures are necessary for prevention of the consecutive explosions when an accident explosion occurs at any chamber. This paper aims to propose an procedure for calculation of the design loads for the chamber blast doors. Modeling considerations are drawn through analyzing the influences of the geometrical shapes and mechanical properties of rocks on the propagation of pressure wave along with the tunnels. Additionally, the design loads for the chamber blast doors in a newly-built underground ammunition facility are calculated based on the proposed procedure.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.41-48
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• 2019

In October 2018, a large fire occurred after an explosion in an internal floating roof tank (IFRT) that stores gasoline by wind lantern in Goyang city, Gyeonggi-do. Although there was no casualty damage, the fire inside the tank lasted for 17 hours, and caused a great wave socially, and it was a chance to review the safety of the atmospheric storage tank. In this study, the necessity of installing a flame arrester at peripheral vents was examined through the calculation of the size of ventilation pipe and ventilation rate of internal floating roof tanks in terms of the function of the peripheral vent. Next, the necessity of the emergency shut-off valve linked with the high-level alarm to prevent the overflow of the atmospheric storage tank was confirmed by LOPA. Finally, safety measures to prevent overpressure, flame propagation and overflow which cause major accidents in atmospheric storage tank are suggested.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.4
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• pp.294-300
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• 2017

The offshore installations and ships are the structures most likely to be exposed to hazards such as hydrocarbon fire and/or explosion. Developing proactive measures to prevent the escalation of such events thus requires detailed knowledge of the related phenomena and their consequences. $CO_2$ extinguishing systems are extensively used for fire accidents of on-and offshore installations because of outstanding performance and low cost. There is, however, the risk of carbon dioxide system which enumerates many of the fatalities by suffocation associated with industrial fire protection requirements. Therefore, the aim of this study is to perform the prediction of fire suppression characteristics of the carbon dioxide system in realistic enclosed compartment area of ships and propose $CO_2$ extinguish fire fighting system for preventing suffocation accidents during fire fighting. According to CFD calculations, it can be observed and assessed that various fire profiles with $CO_2$ and $O_2$ mole fraction in the target enclosed compartment area are applicable within the proposed system. Additionally, the design of fire safety system of ships and offshore installations can utilize ventilation system and/or layout arrangement through the proposed system.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.429-437
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• 2018

The process gas piping of the offshore plant can cause a massive explosion if the gas leakage occurs during operation. For the purpose of precaution of gas leakage accident, an air pressure test is performed on the process equipment tests using a test pump as much as the power to the piping inner side, mix 99% nitrogen gas and 1% helium gas. The purpose of the air pressure test is to check the work conformity process by handling and regulation for initial piping process, assembly, installation of module, welding, center alignment of the pipes assembling flange gasket in an unrestrained free state. In this paper, the regulation of the problematic air pressure test was analyzed and the solution criteria were established. And leakage tests of existing equipment were performed applying these solution methods. As a result, it was confirmed that there was no problem.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.256-261
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• 2019

The use of military lithium batteries in this field accelerates the generation of internal pressure because the active materials, lithium and the electrolyte, react to form sulfur dioxide gas. This also reduces the amount of electrolyte. In this condition, batteries can 'vent' or 'explode' especially when completely discharged. Such venting and explosion can be regarded as a safety accident, as toxic gases and shrapnel are ejected from the batteries which can harm the user. A DTaQ was carried out in 2017 as a quality problem solution project to solve this safety issue. A protection circuit was thereby developed, which included a micro controller unit (MCU) which can stop battery usage when in an over-discharging state by sensing its low-voltage condition. In 2018, this concept was expanded to lithium batteries for the remote controlled ammunition system. This paper reports results of the improved performance.