• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.1939-1950
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• 2019

The MELCOR code useful for a plant-specific hydrogen risk analysis has inevitable limitations in prediction of a turbulent flow of a hydrogen mixture. To investigate the accuracy of the hydrogen risk analysis by the MELCOR code, results for the turbulent gas behavior at pipe rupture accident were compared with CFX results which were verified by the American National Standard Institute (ANSI) model. The postulated accident scenario was selected to be surge line failure induced by station blackout of an Optimized Power Reactor 1000 MWe (OPR1000). When the surge line failure occurred, the flow out of the surgeline was strongly turbulent, from which the MELCOR code predicted that a substantial amount of hydrogen could be released. Nevertheless, the results indicated nonflammable mixtures owing to the high steam concentration released before the failure. On the other hand, the CFX code solving the three-dimensional fluid dynamics by incorporating the turbulence closure model predicted that the flammable area continuously existed at the jet interface even in the rising hydrogen mixtures. In conclusion, this study confirmed that the MELCOR code, which has limitations in turbulence analysis, could underestimate the existence of local combustible gas at pipe rupture accident. This clear comparison between two codes can contribute to establishing a guideline for computational hydrogen risk analysis.

• Nuclear Engineering and Technology
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• v.37 no.6
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• pp.537-556
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• 2005

A primary-pipe rupture accident is one of the design-basis accidents of a High-Temperature Gas-cooled Reactor (HTGR). When the primary-pipe rupture accident occurs, air is expected to enter the reactor core from the breach and oxidize in-core graphite structures. This paper describes an experiment and analysis of the air ingress phenomena and the method fur the prevention of air ingress into the reactor during the primary-pipe rupture accident. The numerical results are in good agreement with the experimental ones regarding the density of the gas mixture, the concentration of each gas species produced by the graphite oxidation reaction and the onset time of the natural circulation of air. A hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR) Is being designed to be able to produce hydrogen by themo-chemical iodine-Sulfur process, using a nuclear heat of 10 MW supplied by the HTTR. The HTTR hydrogen production system is first connected to a nuclear reactor in the world; hence a permeation test of hydrogen isotopes through heat exchanger is carried out to obtain detailed data for safety review and development of analytical codes. This paper also describes an overview of the hydrogen permeation test and permeability of hydrogen and deuterium of Hastelloy XR.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.394.3-395
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• 2002

Dextromethorphan (Romilar. DEX) is a synthetic analogue of codeine. is not classified as a narcotic and is used only for its antitussive effects in Korea. The daily intake by adults range up to 120mg. Usually in the case of traffic accident. alcohol concentration of blood is analyzed in Korea. but drug tests (medicine, narcotic. alcohol) are submitted in Australia. In crimes of violence (2 examples), a traffic and a murder accident. drug testing in urine and blood was performed. (omitted)

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.69-82
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• 2004

Recently, in the food, paper, steel and plastic industries, plate or sheet type products have been produced by the rolling drum. Steam heating drums are introduced into plastic products facilities in order to keep the density, microstructure, and strength of material uniformly. The drum journal can not help being concentrated by stresses due to the bending and torsion. Especially the drum, heated by high pressure steam, might be exposed in the steam leakage accident. First of all, the stresses on the steam drum journal are to be analyzed, and a case study proper to the subject was performed with a scraped journal, in order to investigate the failure characteristics as well as the initiation and propagation of fatigue cracks, and most probable circumstances of crack initiation. As the result of this study, it is suggested that newly installed drum journal be thoroughly inspected at the next periodic maintenance intervals for evidence of cracking, the microstructure examination and hardness measurements to prevent steam drum from the failure accident.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.92-99
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• 2008

The rapid economic growth in Korea raised the increase of transportation demands about the passengers and the goods, and caused the concentration on cities. By the rise of a nation's income level, a automobile is necessary in our modern life. However, the traffic delays and traffic accidents that are raised by automobiles decrease the evaluation about a nation's economy and then the government practices the traffic safety improvement project. In this study, by performing the improvement project, we expect to achieve the following objectives. First, this study analyses the degree of effectiveness whether or not success in the improvement. Second, to supply the data on the effectiveness of the improvement and to inform the necessity of improvement. Third, to supply the information on the improvement project to the parties concerned. In this paper, through the study about identification of high accident locations, the effectiveness for the number of accidents and accident rates before-after the improvement is analyzed. Also, the B/C analysis about this locations is performed. This study shows that the number of accident and accident rates are decreased after the improvement, and there is economic validity about improvement of high accident locations.

• Journal of the Korean Society of Safety
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• v.34 no.6
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• pp.13-21
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• 2019

Leakage accidents in businesses dealing with hazardous chemicals can have a great impact on the workers inside the workplace, as well as residents outside the workplace. In fact, there were cases where hazardous chemicals leaked from many businesses. As a result, the Chemicals Control Act(CCA) was enacted in 2015, the Ministry of Environment introduced an Off-site Risk Assessment(ORA). The purpose of the ORA is to secure safety from the installation of the design of the workplace facilities so that chemical accidents of hazardous chemical handling facilities do not cause human or physical damage outside the workplace. In general, the ORA qualitatively determines where a protected facility is within the scope of the accident scenario. However, elderly who belong to the sensitive group is more sensitive than the general group under the same chemical accident effect, and the extent of the damage is serious. According to data from the Korea National Statistic Office, the number of elderly people is expected to increase steadily. Therefore, a quantitative risk analysis considering the elderly is necessary as a result of a chemical accident. In this study, accident scenarios for 14 locations were set up to perform emergency evacuation due to toxic gas leakage of Cl₂(Chlorine) and HF(Hydrogen Fluoride), and the effects of exposure were analyzed based on the evacuation velocity difference of age 20s and 60s. The ALOHA(Areal Locations of Hazardous Atmospheres) program was used to calculate the concentration for assessing the effects. The time of exposure to toxic gas was calculated based on the time it took for the evacuation to run from the start point to the desired point and a methodology was devised that could be applied to the risk calculation. As a result of the study, the relative risk of the elderly, the sensitive group, needs to be determined.

• Korean Journal of Culture and Social Issue
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• v.12 no.3
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• pp.23-47
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• 2006

The purpose of this research is to study the relation between the change of driver's driving confidence level in the age categories and driving behavior. To survey the driving confidence level, we used the 'Driving Confidence Scale' questionnaire and surveyed the drive career, mileage, driving days, violation of traffic regulation (drunk driving, overspeed), traffic accident experience (assaulter, sufferer) together. The subjects of investigation were from 19-year-old to 80-year-old and 1,055 persons were participated in the research totally. To examinethe structure of driving confidence level, we executed the factor analysis. We compared the driving confidence level in the age categories (under 29-year-old, 30~39, 40~49, 50~64, over 65-year-old) and studied the relation between driving confidence level and driving behavior. Driving confidence level was composed of 4 factors such as 'insensibility to situation', 'unsafe driving', 'careless concentration' and 'self-efficacy of driving', and there was decreasing tendency for driving confidence level and overall driving behavior according to increasing age. Driving confidence level had the interrelation with age range, assaulting accident, suffered accident, driving period, drunk driving, overspeed, driving career and so on. We examined the difference of driving confidence level and driving behavior by dividing the participated drivers' groups into the traffic accident experienced group, drunk driving group and overspeed driving group, and there was a significant difference on driving confidence level and driving behavior between the group who had not experienced the violation of traffic regulation or traffic accident and another group who had experienced the violation of traffic regulation or traffic accident.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.597-609
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• 2020

Accident Tolerant Fuels have been widely studied since the Fukushima-Daiichi accident in 2011 as one of the options on how to further enhance the safety of nuclear power plants. Deposition of protective coatings on nuclear fuel claddings has been considered as a near-term concept that will reduce the high-temperature oxidation rate and enhance accidental tolerance of the cladding while providing additional benefits during normal operation and transients. This study focuses on experimental testing of Zr-based alloys coated with Cr-based coatings using Physical Vapour Deposition. The results of long-term corrosion tests, as well as tests simulating postulated accidents, are presented. Zr-1%Nb alloy used as nuclear fuel cladding serves as a substrate and Cr, CrN, Cr_xN_y layers are deposited by unbalanced magnetron sputtering and reactive magnetron sputtering. The deposition procedures are optimized in order to improve coating properties. Coated as well as reference uncoated samples were experimentally tested. The presented results include standard long-term corrosion tests at 360℃ in WWER water chemistry, burst (creep) tests and mainly single and double-sided high-temperature steam oxidation tests between 1000 and 1400℃ related to postulated Loss-of-coolant accident and Design extension conditions. Coated and reference samples were characterized pre- and post-testing using mechanical testing (microhardness, ring compression test), Thermal Evolved Gas Analysis analysis (hydrogen, oxygen concentration), optical microscopy, scanning electron microscopy (EDS, WDS, EBSD) and X-ray diffraction.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.155-162
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• 2010

Elderly pedestrians account for more than 30% of all deaths in traffic accident and the number of elderly-related traffic accidents are increasing every year. Considering Korea's quickly aging society, drastic measures must henceforth be taken. Taking notice of the elderly living in and moving around the provinces, this research focused on analyzing the characteristics of elderly pedistrians' traffic accidents on provincial roads and developing an Equivalent Property Damage Only (EPDO) model. The authors collected 720 traffic accident data points from the police agency and developed the EPDO model, weighted differently by light injury, severe injury, and death using Multiple Regression Analysis. As a result, the speed of vehicles is the most influential variable in EPDO, and the shape of the road is significant as well. Therefore, various policies should be established like improving the environmental factors of provincial roads, like expanding speed-reduction treatments and signage, and setting up detours around areas of high elderly concentration.

• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.168-177
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• 1998

Five and a half months after the Keumdong oil spill accident on the 21$^{st}$ of September 1993, 34 seawater samples and 94 sediment samples were collected from Kwangyang Bay and Namhaedo area to assess its environmental impacts. Hydrocarbon concentration in the seawater ranged from 0.8 to 9.2 ${\mu}$g/1 with an average of 3.3 ${\mu}$g/1. This average value was nearly the same as the value(3.7 ${\mu}$g/1) before the oil spill accident. This suggests that by the early March of 1994 majority of the coastal water in the study area restored to its background hydrocarbon concentration before the oil spill accident. Nutrients, heavy metals and other general environmental parameters of the seawater did not show any aggravated seawater quality compared with the previous records. From the regression analysis of time-course observation of hydrocarbon in the seawater, except the sediment environment, the effect of oil spill on the water column was estimated to last at least 4 months in the study area after the oil spill accident. In the shoreline sediments, oil deposits were, however, still found at the high water marks at several stations, and very high values were found in the west of Namhaedo, ranging from 3.7 to 40.1 mg/g of wet sediment. Gas chromatography of these samples showed a very distinct Bunker C chromatogram identical to the Keumdong oil spill. Hydrocarbons in the subtidal bottom sediments in the study area and the reference stations (YB and CB) ranged from 0.45 to 18.08 ${\mu}$g/g of wet sediment with an average of 3.09 ${\mu}$g/g. West of Namhaedo (Stations Bl2-B33) generally showed much higher values than inner Kwangyang Bay and in Chinju Bay. Chinju Bay generally showed the lowest value among the study area. Subtidal bottom sediments in inner Kwangyang Bay and Chinju Bay seemed to be less affected than west of Namhaedo. Heavy metal concentrations in the sediment were relatively higher in the Kwangyang Bay than in the Chinju Bay. However, metal concentrations in the study area were in general comparable to the reference areas.