• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.183-194
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• 2019

In recent years, the risk of external flooding of major national facilities has increased significantly since 2000 due to the increase in local heavy rainfall events. For important domestic national facilities, it is necessary to analyze the risk of external flooding as flooding in major sites due to heavy rain can cause functional paralysis in major facilities and ultimately lead to massive trouble events. In order to manage the safety of main facilities and its related facilities at a high level, it is necessary to analyze the degree of disaster such as flood depth, flood flow rate, flood time and flood intensity when extreme floods (LIP) are introduced. In addition, the degree of vulnerability of these related facilities should be assessed and risk assessments should be reassessed through linkage analysis that combines the degree of disaster and vulnerability. By calculating a new flood hazard curve for the flood depth and flood intensity in major national facilities under the heavy rainfall conditions through this study, it is expected to be a basis for the waterproof design of important SOC facilities, flood prevention function design, advancement of flood prevention measures and procedures and evaluation of flood mitigation functions.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.14-25
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• 2018

The combined cycle power plant has a cycle of operating the gas turbine with fuel, such as natural gas, and then producing steam using residual heat. The fuel gas is supplied to the gas turbine at a level of 4 to 5 MPa, $200^{\circ}C$ through a compressor and a heat exchanger. In this study, the risk assessment method considering the piping system stress was carried out for safe operation and soundness of the gas fuel supply piping system. The API 580/581 RBI code, which is well known for its risk assessment techniques, is limited to reflect the effect of piping stress on risk. Therefore, the systematic stress of the pipeline is analyzed by using the piping analysis. For the study, the piping system stress analysis was performed using design data of a gas fuel supply piping of a combined cycle power plant. The result of probability of failure evaluated by the API code is compared to the result of stress ratio by piping analysis.

• Journal of Korea Water Resources Association
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• v.53 no.5
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• pp.323-336
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• 2020

Owing to climate change, the annual precipitation in Korea has increased since the 20th century, and it is projected to continue increasing in the future. This trend of increasing precipitation will raise the possibility of floods; hence, it is necessary to establish national adaptation plans for floods, based on a reasonable flood risk assessment. Therefore, this study focuses on developing a framework that can assess the flood risk across the country, as well as computing the flood risk index (FRI). The framework, which is based on IPCC AR5, is established as a combination of three indicators: hazard, exposure, and capacity. A data-based approach was used, and the weights of each component were assigned to improve the validity of the FRI. A Spearman correlation analysis between the FRI and flood damage verified that the index was capable of assessing potential flood damage. When predicting scenarios for future assessment using the HadGEM3-RA based on RCP 4.5 and 8.5, the flood risk tends to be lower in the early and mid-21st century, and it becomes higher at the end of the 21st century as compared with the present.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.4
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• pp.315-326
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• 2024

In this study, the Delphi method and AHP (analytic hierarchy process) were used to evaluate tunnel collapse risk from a comprehensive and multifaceted perspective. Influence factors were established through literature reviews, previous studies, and brainstorming sessions with expert groups, resulting in the construction of five main classification systems. A panel of 21 experts was formed, and three rounds of Delphi surveys were conducted to prevent errors and biases in the expert judgment process, thereby enhancing reliability. Ultimately, 14 influence factors were identified through CVR (content validity ratio) and COV (coefficient of variation) analyses of the experts' responses. Subsequently, the AHP method was applied to assess the relative importance of each influence factor and calculate the final composite weights. The timing of support and reinforcement had the highest priority, followed by groundwater inflow, joint conditions, support pattern levels, and auxiliary methods. These findings help identify the key factors affecting tunnel collapse risk and provide a foundation for developing strategies to improve tunnel safety.

• Journal of Nutrition and Health
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• v.42 no.2
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• pp.171-182
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• 2009

This study was performed to investigate socioeconomic factors relating to obesity and inadequate nutrient intake in women in low income families residing in Seoul. The subjects were 125 women (aged 41-87 y) recruited from the local health center for free health examination for low income families. The socioeconomic status such as educational level, income level, and housing condition were poor. For subjects aged less than 65 years, the prevalence of obesity was 44% based on BMI (${\geq}\;25\;kg/m^2$), 48% based on WHR (${\geq}\;0.85$), and 50% based on waist circumference (${\geq}\;80\;cm$) and for those more than 65 years, these were greater and 57%, 81%, and 79%, respectively. The main food sources of daily diet were vegetables, grains, and fruits. Energy and other nutrient intake was not adequate for all subjects and the inadequacy was more profound in the elderly, showing percentages of subjects whose intake was less than EAR were greater than 50% for all nutrients except for iron and below RI were also greater than 50% for all nutrients. The prevalence of obesity and nutrient inadequacy were not associated with socioeconomic status in subjects aged less than 65 years, however, obesity was associated with household income and nutrient inadequacy was related to education (vitamin A) and housing status (protein, phosphate, and iron) in the elderly. After adjustment for ages, in the elderly, OR for obesity (BMI ${\geq}$ 25, OR = 12.601; 95% CI = 2.338-67.911) and central obesity (WC ${\geq}$ 80 cm, OR = 4.778; 95% CI = 1.103-20.696) were greater in subjects who earned less than 500 thousand Won per month than who earned more. For inadequate nutrient intake, the OR for inadequate intake of Vitamin A (OR = 4.555; 95% CI = 1.491-13.914) was greater in subjects with no education than those educated. Subjects without her own house had greater risk for inadequate intake for protein (OR = 3.660; 95% CI = 1.118-11.981), phosphate (OR = 3.428; 95% CI = 1.157-10.158), and iron (OR = 3.765; 95% CI = 1.205-11.766) than subjects possessing her house. In elderly females in low income families, the socioeconomic status was associated with the risk for obesity (income level) and inadequate nutrient intake (education level and housing status). More attention on these groups should be given for prevention of obesity and inadequate nutrient intake.

• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.13-19
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• 2006

As a way of improving the safety of the facilities, the risk based-inspection (RBI) was executed for the chemical facilities by using K-RBI program, which has been developed based on the API-581 based resource document (BRD). As the result of the evaluation, we found the level of the process safety management (PSM) for the applied plant, quantitative risk of the applied process, risk of static facilities and pipes, and the damage mechanism of the facilities. Thus, we could suggest a proper inspection frequency using the calculated risk of the process and the status of the facilities. The applied plant achieved a reduced inspection cost by an extension of the inspection frequency, improved productivity, improved reliability of the facilities, and a computerized history management.

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.95-102
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• 2011

This paper presents a Driving Risk Model (DRM) based on driving speed choices using an Ordered Response Probit (ORP) model. The DRM is conceptualized based on the relation between speed deviation and the occurrence of crashes found by Solomon. The impacts of various driving risk factors are revealed by applying the DRM to evaluate the effectiveness of In-Vehicle Traffic Warning Information (IVTWI) in expressway driving. Regarding driving risk, the results show that: (1) the risk is lower among male drivers, those with more driving experience and those with less accident history, (2) the risk is higher when driving takes place on wet road surface, in the afternoon, and under conditions of low traffic volume, and (3) the risk is also higher on both downgraded and long curve sections. Additionally, the results provide evidence that provision of IVTWI can decrease the driving risk. The proposed DRM provides a solution for assessing the traffic safety impacts of countermeasures on roadways when there is a shortage of traffic accidents data.

• Journal of Korean Society of Disaster and Security
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• v.5 no.2
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• pp.61-70
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• 2012

The range of special management target facilities is seperated by the building sector and the field of civil engineering. In the present study, the risk analysis was performed, related to fire occurred for the last five years, in the field of residential and non-residential facilities in buildings. Most of fire incidents occurred in residential and non-residential facilities was the cause of the electrical, and the resulting casualties were also very high. Therefore, based on the results, the risk evaluation index was developed, identifying the causes of fire occur and doing the fire vulnerability analysis for each facility. The result of this study can be utilized safety management to these facilities for the future, especially, inducing a more specialized and intensive safety management.

• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.11-17
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• 2017

The case study on ground subsidence was conducted and the cause of ground subsidence was evaluated, main cause were insufficient site exploration, inaccurate strength parameters, defective temporary wall, insufficient reaction for boiling and heaving, excessive excavation and so on. Risk factors during excavation were identified from the cause of ground subsidence and risk factors were site exploration, selecting excavation method, structure analysis, measurement plan, excavation method construction, underground water level change, natural disaster and construction management. The survey of the experts on risk factors identified was conducted to evaluate the importance of risk factors, and confidence analysis was performed to evaluate the significance level between survey result and survey respondent using Chi-square Test.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.1
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• pp.42-60
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• 2024

This study analyzed the characteristics of mixed traffic flows with autonomous vehicles on highway weaving sections and assessed the safety of vehicle-following pairs based on surrogate safety indicators. The intelligent driver model (IDM) was utilized to emulate the driving behavior of autonomous vehicles, and the weaving sections were divided into lengths of 300 and 600 meters for analysis within a micro-traffic simulation (VISSIM). Although significant differences were found in the average speed, density, and headway between the two sections through t-test results, no significant differences were observed when comparing the number of conflicts per indicator and the vehicle-following pair. Four safety indicators were selected for the mixed traffic evaluation based on their ability to represent risk levels similar to those perceived by drivers. The safety analysis, based on the selected four indicators, determined that autonomous vehicles following other autonomous vehicles were the safest pairing. Future research should focus on integrating these indicators into a single comprehensive index for analysis.