• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.57-64
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• 2013

Recently, bicycle accidents have increased with the ever-increasing number of cyclists. Bicycle accidents occurred frequently in intersections, and the perpendicular collision between a right-turning car and a crossing bicycle was the most prevalent accident type. In particular, the collision was caused by motorists' carelessness. In other words, the accident-involved motorists did not pay sufficient attention to a bicycle crossing behind them. Another cause was a cyclist's higher speed than pedestrians. This paper evaluated the potential risk of the collision between right-turning cars and crossing bicycles based on simulation experiments, with motorists' speed and carelessness focused on. Consequently, it was found that to reduce the potential risk of the collisions a motorist should slow down and pay more attention to the rear sight by turning his/her head.

• Korean Journal of Transplantation
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• v.32 no.4
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• pp.92-103
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• 2018

Background: Currently, trimethoprim-sulfamethoxazole is used for Pneumocystis jirovecii pneumonia (PJP) prophylaxis, but it is associated with frequent adverse effects. This study evaluated the efficacy and safety of the current protocol and proposes an individualized risk-based prophylaxis protocol. Methods: The PJP incidence and risk factors during the first 6 months (early PJP) and afterwards (late PJP) was assessed in renal transplant recipients with (prophylaxis group) and without (no-prophylaxis group) 6-month PJP prophylaxis. Results: In 578 patients, there were 39 cases of PJP during a median follow-up of 51 months. Renal adverse events were encountered frequently during trimethoprim-sulfamethoxazole prophylaxis, leading to premature discontinuation. Patients without the prophylaxis had a significantly higher incidence of early PJP (n=27, 6.6%) compared to patients with the prophylaxis (n=0). The incidence of late PJP was 2.2%, without between-group differences. The factors associated with early PJP were preoperative desensitization and acute rejection within 1 month, whereas late PJP was associated with age, deceased donor transplant, and acute rejection requiring antithymocyte globulin treatment. Conclusions: Based on the simulation results of several risk-based scenarios, the authors recommend universal prophylaxis up to 6 months post-transplant and extended selective prophylaxis in patients aged ${\geq}57$ years and those with a transplant from deceased donors.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.863-869
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• 2018

Due to recent changes in the maritime traffic environment, naval warship accidents are constantly occurring. Especially in 2017, serious loss of life was caused by a US navy destroyer accident. The purpose of this study is to analyze the characteristics of naval warship accident cases and construct an accident scenario by using naval training materials, adjudication of naval warship accidents and US navy destroyer accident reports. Based on the surveyed data, the status of accidents was identified and cases were analyzed. We reproduced 17 accident cases in accordance with accident reproduction procedure and constructed naval warship accident scenarios. As a result of analyzing the CPA, TCPA and PARK model for risk, reproducing 17 naval ship accident cases, collision risk increased on average 5-6 minutes before an accident. The result of this study represents basic data for naval and simulation education materials, contributing to the prevention of marine accidents.

• Journal of the Korean Institute of Rural Architecture
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• v.23 no.4
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• pp.38-45
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• 2021

In this study, air quality conditions were identified and analyzed in real time, at the same time, living habits and ventilation methods were maintained in the daily life of residents, and thus, this present study focuses on the lifestyles of residents. Previous studies showed a difference from this study, focusing on the study on the effects of changes in indoor air quality on human health according to the indoor air quality process test standards of the Ministry of Environment. Formaldehyde concentrations exceeded all ventilation standards, but satisfied the organic standards of the Ministry of Environment when ventilation devices and air purifiers were activated. As such, it was investigated that a large amount of formaldehyde emission in the condo is initially ventilated, but a certain concentration is maintained. The change in PM2.5 concentration according to the ventilation method showed a clear difference. As a result of simulating indoor air flow during natural ventilation, the effects of wind speed and wind direction affect the flow rate of indoor air, and indoor polluted air is stagnant even in the presence of wind and is not completely discharged. When the risk assessment results are averaged on the day of measurement, the trends of change between adults and children are almost equivalent, but the results address that children are more sensitive to risk than adults.

• Fire Science and Engineering
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• v.15 no.1
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• pp.84-92
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• 2001

In today's world, rise in the establishment of social infrastructure resulting from population saturation in large cities has led to more extensive and frequent use of chemical materials on facilities. A result, unexpected and serious accidents, hazards, contingencies and disasters are more prevalent than ever. Such phenomenon calls for more devoted and concerted efforts towards finding ways to reduce the safety hazards that are seen to take place more often than before with the increase in the number of facilities that are prone to bring disaster and hazard coupled with the conventional safety problems that continue to exist even today. In developed countries, such challenge is addressed by various appropriate countermeasures drawn up by local professional committees on industrial facilities, whose members conduct offsite and onsite evaluation un the potential industrial disasters and its seriousness and provide their advice thereof. Against this backdrop, this study aims at identifying a comprehensive safety allowance level (safety acceptable level) when imposing limitation on the development of conventional or new facilities, for the fur pose of establishing a safety allowance level of disastrous and dangerous facilities in Korea. This is done by assessing and applying the level of danger each individual is exposed to in a randomly selected region (disastrous and dangerous areas in Seoul) based on probability of quantitative hazards, as well as simulation and calculation methods which include: i) social disaster evaluation method applying Quantified Risk Assessment of Health & Safety Executive of UK and Matrix of Risk of Evaluated Sources of Hazard; ii) Fault Tree or Event Tree Analysis and etc.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4661-4664
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• 2012

Mammographic breast density is a known risk factor for breast cancer. To conduct a survey to estimate the distribution of mammographic breast density in Korean women, appropriate sampling strategies for representative and efficient sampling design were evaluated through simulation. Using the target population from the National Cancer Screening Programme (NCSP) for breast cancer in 2009, we verified the distribution estimate by repeating the simulation 1,000 times using stratified random sampling to investigate the distribution of breast density of 1,340,362 women. According to the simulation results, using a sampling design stratifying the nation into three groups (metropolitan, urban, and rural), with a total sample size of 4,000, we estimated the distribution of breast density in Korean women at a level of 0.01% tolerance. Based on the results of our study, a nationwide survey for estimating the distribution of mammographic breast density among Korean women can be conducted efficiently.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.17-22
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• 2004

Ship is bring operated under a highly dynamic environments and many factors are related whit marine accident and those factors are interacting. An analysis on the marine accident is very important to prepare countermeasures which will ensure the safe navigation. This paper aims to build a model of the causes and improved policy for marine accident using SD(System Dynamics} approach and to measure a effect which is risk control countermeasures of marine accident. The methodology of this paper is to perform the causes and improved policy for marine accident using Brainstorming method and was to changed by quantitutive, qualitative factors and their feedback loops in casual map. This model was performed over 23 years($1997\~2020$) in a standard simulation model and 4 policy simulation models.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.1
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• pp.47-55
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• 1998

In this paper, authors try to assess the marine traffic environment from the viewpoint of the degree of congestion. First, the marine traffic flow simulation is carried out to get the information related to the assessment. The simulation is performed based on the wide investigation of marine traffic environment and some statistical methods. Then the degree of congestion is reasoned by using the reasoning methods of the degree of collision risk made to develop collision avoidance system. The quantified degree of congestion reasoned by this method provides much information needed to the design and the evaluation of marine traffic environment.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.529-532
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• 2001

The purposes of the present study are to investigate hemodynamic characteristics and to define shear-sensitive remodeling in the stenosed coronary models. Two models for the compensatory remodelling used for this research are a pre-stenotic dilation and a post-stenotic dilation models for the computer simulation. The peak wall shear stress on the post-stenotic model is higher than that of the pre-stenotic model. Two recirculation zones are generated in the pre-stenotic model, and the zones in the pre-stenotic model are smaller than those in the post-stenotic model. Variation of the wall shear stress in the pre-stenotic model is lower than that in the post-stenotic model. In computer simulation with the post-stenotic model, higher temporal and spatial shear fluctuation and stress suggested shear-sensitive remodeling. Shear-sensitive remodeling may be associated with the increased risk of plaque rupture, the underlying cause of acute coronary syndromes, and sudden cardiac death.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.101-105
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• 2002

In a traditional hierarchical inventory system, direct orders are the only information for inventory management that is exchanged between the firms involved. But due to the rapid development of modern information technology, it becomes possible for the firms to share more information in real time, e.g. demand and inventory status data. And so the term Supply Chain has emerged because it is seen as an important source of competitive advantage. Now it is possible to challenge traditional approaches to inventory management. In the past, one of the de-facto assumptions for inventory management was that the demand pattern follows a specific distribution function. However, it is undesirable to apply this assumption in real situations because the demand information in the supply chain tends to be distorted due to the bullwhip effect in a supply chain. To overcome this weakness, we propose a new solution method using NN (Neural Network). Our method proceeds in three steps. First, we find the patterns of optimal reorder points by analyzing past data. Second. train the NN using these pattern data and finally decide the reorder point. Using simulation experiment, we show that the proposed solution method gives better result than that of traditional research.