• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.293-310
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• 2020

The purpose of this study is to present the most effective smoke exhaust mode by comparing the quantitatively evaluated risks according to the smoke exhaust mode when a train fire occurs in a subway platform. Therefore, applying the typical subway platform as a model, train fire scenarios are developed with the evacuation start time and location of the fire train for each exhaust mode. The fire accident rates (F) are calculated and the number of fatalities (N) was quantitatively estimated by fire analysis and evacuation analysis for each scenario. In addition, the F/N curve compared with the social risk assessment criteria and the following conclusions were obtained. In the event of a train fire at the subway station platform, the evacuation must start up within 600 s in maximum to ensure the evacuees' safety. To secure evacuation safety, it is advantageous to operate the HVAC system of the platform in the air-supply mode at station without TVF. Comparing the F/N curve for each exhaust mode with the social risk criteria, it turned out that the risk significantly exceeds the social risk criteria in case of no mechanical ventilation. As a result, this paper shows that the ventilation mode in which TVF are exhausted and HVAC system is operated in the pressurized mode are the most effective smoke exhaust mode for ensuring evacuation safety.

• Korean Journal of Community Nutrition
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• v.10 no.6
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• pp.905-919
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• 2005

This study raised the necessity of developing performance indicators for measuring the management efficiency and effectiveness of school food service, and as a means of helping its implementation, a balanced score card (BSC) approach developed by Norton and Kaplan was adopted. This study established BSC in seven phases through literature: Phase 1 Defining a school food service and the scope of working activities, Phase 2 Establishing the vision of a school food service, Phase 3 Setting strategic goals, Phase 4 Identifying critical success factors (CSFs), Phase 5 Developing Key Performance Indicators (KPIs), Phase 6 Extracting cause and effect relationship, and Phase 7 Completing a preliminary BSC. The preliminary BSC was fumed into a survey, which was administered to food service related people working at the Office of Education and School Food Service including 16 offices,209 dietitians, 48 school administrators both from self-operated and contract-managed, and 9 experts in areas related to school food service. They were asked questions about strategies from 4 different perspectives,12 CSFs, 39 KPls, and the cause and effect relationships among them. As a result, among the CSFs based on 4 different perspectives, all factors other than ' zero sum on profit/loss ' from the financial perspective turned out to be valid. In terms of KPIs, manufacturing cost percentages, casualty loss count/reduction rates, school foodervice participation rates, and sales goal achievement rates were found to be valid from the financial perspective, while student satisfaction index, faculty satisfaction index, leftover ratio, nutrition educational performance count, index of evaluating nutrition education, customer claim count/reduction rate, handling customer claim count/reduction rate, and parent satisfaction index were found to be valid from the customers' perspective. Besides, nutritional requirement sufficient ratio, nutritional management score, food poisoning outbreak count, employee safety accident count, sanitary inspection assessment index, meals per labor hour (productivity index), computerization ratio, operational management index, and purchase management assessment index were also found to be valid from the perspective of internal business processes. From the perspective of innovation and learning, employee turnover ratio/rate of absenteeism, annual education and training count, employee satisfaction index, human resource management assessment index, annual menu-related customer feedback, food service information index for employees and parents/schools were also found to be valid. The significance of this study is to present indices for measuring overall performance of school lunch food service operations without putting any limitation on types of school food service management, and to help correctly assess the contribution of the current types of school food service management to schools and students. (Korean J Community Nutrition 10(6) : $905\∼919$, 2005)

• Korean Journal of Occupational Health Nursing
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• v.22 no.3
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• pp.249-256
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• 2013

Purpose: This study was conducted to compare the rates of industrial accidents in workplaces that adopted the 2011 Workplace Health Promotion Subsidy Scheme before and after the implementation. Methods: The study analyzed the raw data of industrial accidents of 304 workplaces which received subsidies for health promotion activities in 2011. The raw data covered the period from February 2010 to July 2012, based on the dates of industrial accidents. Results: Workplaces subsidized for health promotion activities reported fewer occurrences in staff injuries and illnesses than before the subsidization, as the total number of industrial accident victims dropped from 0.35 to 0.24. The rate of industrial accidents also dropped from 0.49 to 0.35, with the number of working days decreased from 35,433 to 23.867, about 33%. Conclusion: The study showed that financial support for health-promoting activities contributed to the decease in industrial accidents, which is an important indication advocating the need for corporate and government investment on workers health promotion programs. Furthermore, this study is also significant as it is the first research conducted in Korea to examine the impact of a workers health promotion project using a direct indicator, the rate of industrial accidents.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.161-169
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• 2024

This study employs Bayesian network analysis to quantitatively evaluate the risk of incidents in trap boats, utilizing accident compensation approval data spanning from 2018 to 2022. With a dataset comprising 1,635 incidents, the analysis reveals a mortality risk of approximately 0.011 across the entire trap boat. The study significantly identifies variations in incident risks contingent upon fishing area and fishing processes. Specifically, incidents are approximately 1.22 times more likely to occur in coastal compared to offshore, and the risk during fishing processes outweighs that during maintenance operations by a factor of approximately 23.20. Furthermore, a detailed examination of incident types reveals varying incidence rates. Trip/slip incidents, for instance, are approximately 1.36 times more prevalent than bump/hit incidents, 1.58 times more than stuck incidents, and a substantial 5.17 times more than fall incidents. The study concludes by providing inferred mortality risks for 16 distinct scenarios, incorporating fishing areas, processes, and incident types. This foundational data offers a tailored approach to risk mitigation, enabling proactive measures suited to specific circumstances and occurrence types in the trap boat industry.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.973-979
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• 2024

In the framework of the Generation IV research and development project, in which the French Commission of Alternative and Atomic Energies (CEA) is involved, a main objective for the design of Sodium-cooled Fast Reactor (SFR) is to meet the safety goals for severe accidents. Among the severe ones, the Unprotected Transient OverPower (UTOP) accidents can lead very quickly to a global melting of the core. UTOP accidents can be considered either as slow during a Control Rod Withdrawal (CRW) or as fast. The paper focuses on fast UTOP accidents, which occur in a few milliseconds, and three different scenarios are considered: rupture of the core support plate, uncontrolled passage of a gas bubble inside the core and core mechanical distortion such as a core flowering/compaction during an earthquake. Several levels and rates of reactivity insertions are also considered and the thermal-mechanical behavior of an ASTRID fuel pin from the ASTRID CFV core is simulated with the GERMINAL code. Two types of fuel pins are simulated, inner and outer core pins, and three different burn-up are considered. Moreover, the feedback from the CABRI programs on these type of transients is used in order to evaluate the failure mechanism in terms of kinetics of energy injection and fuel melting. The CABRI experiments complete the analysis made with GERMINAL calculations and have shown that three dominant mechanisms can be considered as responsible for pin failure or onset of pin degradation during ULOF/UTOP accident: molten cavity pressure loading, fuel-cladding mechanical interaction (FCMI) and fuel break-up. The study is one of the first step in fast UTOP accidents modelling with GERMINAL and it has shown that the code can already succeed in modelling these type of scenarios up to the sodium boiling point. The modeling of the radial propagation of the melting front, validated by comparison with CABRI tests, is already very efficient.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.124-132
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• 2016

In order to estimate the effect of flow distributors connected to an upper nozzle of CMT(Core Makeup Tank) on the thermal-hydraulic characteristics in the tank, a simplified 2 inch Small Break Loss of Coolant Accident(SBLOCA) was simulated by skipping the decay power and Passive Residual Heat Removal System(PRHRS) actuation. The CMT is a part of safety injection systems in the SMART (System Integrated Modular Advanced Reactor). Each test was performed with reliable boundary conditions. It means that the pressure distribution is provided with repeatable and reproducible behavior during SBLOCA simulations. The maximum flow rates were achieved at around 350 seconds after the initial opening of the isolation valve installed in CMT. After a short period of decreased flow rate, it attained a steady injection flow rate after about 1,250 seconds. This unstable injection period of the CMT coolant is due to the condensation of steam injected into the upper part of CMT. The steady injection flow rate was about 8.4% higher with B-type distributor than that with A-type distributor. The gravity injection during hot condition tests were in good agreement with that during cold condition tests except for the early stages.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.3
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• pp.201-209
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• 2016

The object of this study was to evaluate the separation distance from a temporary storage facility satisfying the dose criteria. The calculation of ambient dose rates took into account cover soil thickness, facility size, and facility type by using MCNPX code. Shielding effects of cover soil were 68.9%, 96.9% and 99.7% at 10 cm, 30 cm and 50 cm respectively. The on-ground type of storage facility had the highest ambient dose rate, followed by the semi-ground type and the underground type. The ambient dose rate did not vary with facility size (except $5{\times}5{\times}2m\;size$) due to the self-shielding of decontamination waste in temporary storage. The separation distances without cover soil for a $50{\times}50{\times}2m\;size$ facility were evaluated as 14 m (minimum radioactivity concentration), 33 m (most probably radioactivity concentration), and 57 m (maximum radioactivity concentration) for on-ground storage type, 9 m, 24 m, and 45 m for semi-underground storage type, and 6 m, 16 m, and 31 m for underground storage type.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1161-1175
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• 2018

An unexpected event could be easily followed by a large secondary accident due to the limitation in sight of drivers in road tunnels. Therefore, a series of automated incident detection systems have been under operation, which, however, appear in very low detection rates due to very low image qualities on CCTVs in tunnels. In order to overcome that limit, deep learning based tunnel incident detection system was developed, which already showed high detection rates in November of 2017. However, since the object detection process could deal with only still images, moving direction and speed of moving vehicles could not be identified. Furthermore it was hard to detect stopping and reverse the status of moving vehicles. Therefore, apart from the object detection, an object tracking method has been introduced and combined with the detection algorithm to track the moving vehicles. Also, stopping-reverse discrimination algorithm was proposed, thereby implementing into the combined incident detection processes. Each performance on detection of stopping, reverse driving and fire incident state were evaluated with showing 100% detection rate. But the detection for 'person' object appears relatively low success rate to 78.5%. Nevertheless, it is believed that the enlarged richness of image big-data could dramatically enhance the detection capacity of the automatic incident detection system.

• Journal of the Korean Society for Railway
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• v.19 no.1
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• pp.77-86
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• 2016

Before urban railway vehicles reach their design life-span, operating agencies should determine when to buy new vehicles. Previous LCC (Life Cycle Cost) studies were limited because they independently focused on existing vehicles based on costs that directly impacted only the operating agency without considering effects such as social costs and the reduction of maintenance costs. Thus, it is difficult to systematically determine when to buy new vehicles. This study investigated the operating and maintenance related costs, especially from additional expenses and social costs due to unexpected vehicle failures and safety accidents, and did an economic analysis of scenarios with different discount rates. Considering that the public is very concerned about safety after the Sewol ferry accident, additional costs, which include social costs, should be included in the analysis. This study shows that the economic priority of scenarios may change depending on whether those costs are included and on the discount rate. The results of this study can help in the decision-making process for the planning and buying of new trains.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.337-345
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• 2015

After the Fukushima nuclear accident in 2011, concerns about radiation by people are increasing rapidly. If people could know how much they will be exposed by radiation, it may help them avoiding it and understand what exactly radiation is. By doing this, we were helping to reduce the anxiety of radiation contamination. In this study, we have researched figures of radioactivity with 'Captus-3000 thyroid uptake measurement systems' in well counter detector system. The materials were measured with Briquette, Shiitake, Pollock, Button type battery, Alkaline battery, Topsoil, Asphalt, Gasoline, Milk powder, Pine, Basalt stone, Pencil lead, Wasabi, Coarse salt, Tuna(can) Cigar, Beer, and then we categorized those samples into Land resources, Water resources, Foodstuff and Etc (Beer classified as a water resources has been categorized into Foodstuff). Also, we selected the standard radiation source linear 137Cs to measure the sensitivity of well counter detector. After that, we took cpm(counter per minute) for the well counter detector of thyroid uptake system's sensitivity. Then we compared the results of each material's cpm and converted those results to Bq/kg unit. There were a little limitation with the measurement equipment because it has less sensitivity than other professional equipment like 'High purity germanium radiation detector'. Moreover, We didn't have many choices to decide the materials. As a result, there are macroscopic differences among the rates of material's spectrum. Therefore, it had meaningful results that showed how much each material had emitted radiation. To compare the material's cpm with BKG, we've compounded their spectrums. By doing that, we were able to detect some differences among the spectrums at specific peak section. Lastly, Button type battery, Alkaline Battery, Briquette, Asphalt and Topsoil showed high value. There were classified emitting high radiation Group A and emitted lower radiation Group B. The Group A, alkaline battery showed higher rate of radiation by 7.67 %, and Button type battery was yield 4.65 % higher rate than BKG. Additionally, Asphalt (8.03 %), Topsoil (3.76 %), Briquette (7.46 %) were yield for higher values. Several samples of the daily supplies were yield little higher, but it seems safe to use in daily lives. In the case of the 'Foodstuff', all of the samples were safe and they were under the radiation limits of the Ministry of Food and Drug Safety for Food; thus, we highly recommend this study to you as a reference of common daily routine.