• Fire Science and Engineering
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• v.26 no.4
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• pp.31-41
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• 2012

This study collected 5,100 cases of gas accident occurred in Korea for 14 years from 1995 to 2008, established Database and based on it, analyzed them by detailed forms and reasons. As the result of analyzing the whole city gas accidents with Poisson analysis, the item of "Careless work-Explosion-Pipeline' showed the highest rate of accidents for the next 5 years. And, "Joint Losening and corrosion-Release-Pipeline" showed the lowest rate of accident. In addition, for the result of analyzing only accidents related to LPG vaporizer, "LPG-Vaporizer-Fire" showed the highest rate of accident and "LPG-Vaporizer-Products Faults" showed the lowest rate of accident. Also, as the result of comparing and analyzing foreign LPG accident accompanied by Jet fire, facility's defect which is liquid outflow cut-off device and heat exchanger's defect were analyzed as the main reason causing jet fire, like the case of Korea, but the number of accidents for the next 5 years was the highest in "LPG-Mechanical-Jet fire" and "LPG-Mechanical-Vapor Cloud" showed the highest rate of accidents. By grafting Poisson distribution theory onto gas accident expecting program of the future, it's expected to suggest consistent standard and be used as the scale which can be used in actual field.

• Convergence Security Journal
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• v.18 no.1
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• pp.143-155
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• 2018

The purpose of this study is to extract the failure attributions to identify the failure factors of the security guards and to derive the risk factor factors through failure cases analysis. Failure attributions were prepared by using semi-structured questionnaires(17) and closed questionnaires(179) starting from the fully open questionnaires(8), and processed through SPSS 21.0 and AMOS 21.O statistical packages. As a result of summarizing the causal relationship between the failure attribution and the failure case (patrol failure pattern factor), In Park Jung-Hee's assassination, lack of experience(2), negative mind(1), lack of work ability(1), lack of experience(2), organizational non-system activeness(2), lack of awareness of mission(1) Failure(2), lack of consciousness(2), and 14 failure patterns were found. Aung-San National Cemetery explosion occurred in eight failure patterns including insecurity(1), negative mind(1), lack of work skills(2), lack of experience(2), individualism(1), There were eight failure patterns in the case of Mr. Yook Young-Su 's sniping, including insincerity(2), negative mind (1), lack of experience(2), lack of awareness of mission(2) and failure to share work(1).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.1
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• pp.83-93
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• 2021

Objectives: 'Confined space' was only defined in the Safety and Health Regulations as a place where oxygen deficiency and hydrogen sulfide must be dealt with at the time of the initial enactment (1982). The danger of fire and explosion were added in 2003. We will compare and review the regulations related to confined space work under the current safety and health rules alongside regulations in other countries and prepare a plan to improve the system through enhanced clarity and execution. Methods: In a comparison of systems for the prevention of suffocation in confined spaces in major countries (Germany, United States, Japan) different concepts of the definition of confined spaces in different countries apparently due to differences in each country's legal implementation system, accident analysis methods, the status of safety and health implementation in workplaces, the precautions against actual confined space work, and the definition of confined spaces were found to be not much different between Korea and the other foreign countries. Results: In the case of Germany and the United States, a confined space is defined as a contextual concept rather than a place, so more careful attention is needed from operators or enclosed space managers as it is often necessary to judge the actual workplace. In the case of Korea and Japan, the interior of the place is mainly defined as a place, especially in the case of Japan, which concentrates on oxygen deficiency and hydrogen sulfide poisoning. Conclusions: For measures to improve regulations on the prevention of suffocation accidents in Korea, I would like to propose three major measures to improve the system in the rules on domestic industrial safety and health standards. It is necessary to prepare and provide a guide to ensure that the 18 types of confined spaces currently defined as confined spaces are clearly understood by field management supervisors or workers.

• Nuclear Engineering and Technology
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• v.41 no.5
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• pp.575-602
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• 2009

In the wake of the Three Mile Island accident, vigorous research efforts were initiated to acquire a basic knowledge of the progression and consequences of accidents that involve a substantial degree of core degradation and melting. The primary emphasis of this research was placed on containment integrity, with: i) hydrogen combustion-detonation, ii) steam explosion, iii) direct containment heating (DCH), and iv) melt attack on the BWR Mark-I containment shell identified as energetic processes that could lead to early containment failure (i.e., within the first 24 hours of the accident). Should the core melt fail the reactor vessel, then non-condensable gas production from Molten Core-Concrete Interaction (MCCI) was identified as a mechanism that could fail the containment by pressurization over the long term. One signification question that arose as part of this investigation was the effectiveness of water in terminating an MCCI by flooding the interacting masses from above, thereby quenching the molten core debris and rendering it permanently coolable. Successful quenching of the core melt would prevent basemat melt through, as well as continued containment pressurization by non-condensable gas production, and so the accident progression would be successfully terminated without release of radioactivity to the environment. Based on these potential merits, ex-vessel corium coolability has been the focus of extensive research over the last 20 years as a potential accident management strategy for current plants. In addition, outcomes from this research have impacted the accident management strategies for the Gen III+LWR plant designs that are currently being deployed around the world. This paper provides: i) an historical overview of corium coolability research, ii) summarizes the current status of research in this area, and iii) highlights trends in severe accident management strategies that have evolved based on the findings from this work.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.10
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• pp.530-537
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• 2017

Scales generated inside pipes cause negative effects on heat transfer performance, pressure loss and flow rate due to increased thermal resistance and reduced flow cross-sectional area. If these scales are not prevented or eliminated, thermal-fluid performance of the facilities can be deteriorated, or in extreme cases, accidents such as explosion due to overheating can occur. There are two ways to remove the scales, physically and chemically. Removing the scales physically needs specific machines which are expensive, and removing them chemically may provoke corrosion or shorten the age of the facilities. In this study, an eco-friendly pipe scale cleaner using natural organic acid is developed by applying the concept of a limestone cave generation. The manufactured scale cleaner is applied to remove the scales in industrial, water heating and urinal pipes. The results show that this cleaner removes scales more effectively and safely compared to existing scale treatments. Scale removal efficiencies of this work is 1.2~10.7 times for industrial pipes and 1.8~15.5 times for boiler water heating pipes higher than those of conventional cleaners.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• Fire Science and Engineering
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• v.27 no.6
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• pp.115-121
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• 2013

Industrial facilities are becoming bigger and more up to date, And a kind of the hazardous material used in the industrial filed is diversified. Therefore, serious accidents such as leakage of toxic materials, fire and explosion, is continuously occurred. There is Process Safety Management (PSM) system of the several preventive systems, but it is supposed to be a limitation to ensure safety or huge PSM industrial sites where have potential to catastrophically invisible and unexpected risks because it is still being managed by instruction and inspection of authority having jurisdiction other than self-regulating management differing from the primarily aim of PSM system. To verify safety management system of work-place, supplementation of existing system is urgently required. In this study, it suggests that PSM self-audit be emphasized significantly analyzing problems of the current systems for enhancing self-audit be emphasized significantly analyzing problems of the current systems for enhancing self-control safety through efficient self-audit management and improving the existing system and improving the existing as verifying the system there of, as well as studying methods which can support institutionally.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.516-525
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• 2000

Recently, the demand for pollution-free demolition work of old reinforced concrete and steel structure has rapidly increased as the redevelopment of urban area has been accelerated. This study deals with linear shape charges for explosive jet cutting on steel structure. We have tested material and shape of steel structure, characteristics of thickness and strength, shape of linear shape charges, type of shape charges, cumulative charges, type of liner, stand-off distance, detonation method. effect of sound and vibration by air blast in explosive jet cutting method. So, We developed linear shape charges in order to take advantage of optimum explosive jet cutting condition. Shape charges were made of PETN explosives. We obtained the experimental formula to decide the amount of explosive needed for thickness of steel structure plate. There are prospects for application of the explosion curving technology under the open space conditions for dismantling the steel structure and steel bridge, scrapped old boats, which are going out of service.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.3
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• pp.279-285
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• 2012

It is necessary to install the inert gas system(IGS) for preventing fire and explosion in LNGC main diesel engine crankcase besides oil mist detector(OMD) unit with $CO_2$ gas injector. Therefore, to design the liquid nitrogen IGS, analytical work is conducted for predicting the heat input load of liquid nitrogen heater with two-phase stratified flow model. This paper also presents the effects of changes in pipe diameter, saturated pressure, and inclination angle by ship's movement on cryogenic two-phase stratified flows. It is found that the stratified model gives reasonable predictions, and the model is effective to predict the heat input load of liquid nitrogen IGS.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.1
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• pp.33-47
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• 2013

When a bomb explodes near a tunnel, generated muck should be quickly moved outside for rehabilitation of the tunnel. In this study, the amount of muck generated by an explosion was estimated and a methodology was presented for the prediction of the muck hauling time. To this end, 3D-meshes were made by using SoildWorks and blasting analyses were performed by using AUTODYN. A method was suggested to calculate theoretically the amount of muck which inflows into a tunnel based on the relationship between the tunnel and the fragmentation zone obtained from the analysis results. Also, muck hauling times were predicted based on the selection of construction equipment and the results were compared and analyzed. As a result, it was convinced that the amount of muck flowing into the tunnel could be effectively calculated by classifying the relationship between a tunnel and the fragmentation zone into 4 cases and using the mensuration by parts. Also it was confirmed that the closer blasting location is to the portal and the excavation surface of a tunnel, and the more blasting location deviates from the center line of the tunnel, the lesser amount of muck occurs and thus the muck hauling time decreases as well.