• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.33-39
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• 2017

A top priority in the design of underwater vehicle is to guarantee the dependability of the electric system because failure of the electrical power supply system is directly related to the life of the passengers. In this paper, we present four kinds of alternative designs to improve reliability of electrical system in underwater vehicle. To reduce the risk and to increase availability of the electrical system, we use the redundancy of the grid structure and power converter. For all design alternatives, we carry out Fault Tree Analysis. Based on the FTA result, we implement RAM simulation to compare the risk and availability for the proposed design alternatives.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1297-1306
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• 2019

Probabilistic safety assessments (PSA) have been used for several decades to visualize the risk level of commercial nuclear power plants (NPPs). Since the role of a human reliability analysis (HRA) is to provide human error probabilities for safety critical tasks to support PSA, PSA quality is strongly affected by HRA quality. Therefore, it is important to understand the underlying limitations or problems of HRA techniques. For this reason, this study conducted a survey among 14 subject matter experts who represent the HRA community of domestic Korean NPPs. As a result, five significant HRA issues were identified: (1) providing a technical basis for the K-HRA (Korean HRA) method, and developing dedicated HRA methods applicable to (2) diverse external events to support Level 1 PSA, (3) digital environments, (4) mobile equipment, and (5) severe accident management guideline tasks to support Level 2 PSA. In addition, an HRA method to support multi-unit PSA was emphasized because it plays an important role in the evaluation of site risk, which is one of the hottest current issues. It is believed that creating such a catalog of prioritized issues will be a good indication of research direction to improve HRA and therefore PSA quality.

• Journal of the Korean Society of School Health
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• v.35 no.3
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• pp.92-103
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• 2022

Purpose: The purpose of this study was to prepare basic data for education and policy proposals related to enhancement of happiness by identifying factors affecting the subjective happiness among Korean adolescents by family type. Methods: The study was a secondary analysis using the raw data of the 16th Youth Risk Behavior Web-based Survey (2020). A complex sample multiple logistic regression analysis was conducted to identify factors affecting adolescent happiness by family type. Results: As a result, the factors that commonly affect the subjective happiness of adolescents for all family types were identified as economic status, academic performance, perceived stress, and loneliness. Additional factors that affect the subjective happiness of adolescents of both Korean two-parent and single parent families were sleep and subjective health status. Financial assistance, number of toilets, breakfast, exercise, depression, suicidal ideation, and suicide attempt were also reported for Korean two-parent families. Conclusion: This study provided empirical basic data for enhancing adolescent happiness in consideration of priority targets and family composition characteristics by identifying factors affecting subjective happiness by family type. Adolescent happiness is a factor that should be actively pursued at home, school, and society, and it should be the goal of education for holistic growth of students.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.83-88
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• 2013

Foreign matters in foods are important food safety issue of consumers, retailers, food manufacturers and food safety authorities in Korea. In order to provide information for development of risk management options and detection technology for foreign matters, multifactorial risk of foreign matters in foods was estimated based on various factors including detection rate, health adverse effect, economic and social aspects. For the each of five food items and foreign matters which were selected from previous study, factors including detection rates, health adverse effects, annual production amounts and willingness to additional pay to reduce foreign matters in foods were quantitatively estimated. The highest risk score was estimated for metal-noodle combination followed by insect-noodle and metal-beverage combinations. The multifactorial risk assessment on foreign matters in food could provide useful information to support risk managers and scientist in complex decision making when various factors should be concerned and different food-foreign matter combinations are compared.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.585-592
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• 2017

Most sewer lines buried in the city are likely to be collapsed due to serious aging. Also, due to the high concentration of development and high population density and traffic, the collapse of the sewer will cause enormous social and economic damage. Therefore, proactive maintenance is required to prevent accidents caused by deteriorated sewer pipe. In order to utilize limited budget effectively, risk-based prioritization methods should be proposed that simultaneously consider the consequence of failure and the probability of failure. In this study, the method of risk-based prioritization of sewer was examined by reviewing various cases of overseas studies and applied to the urban sub-catchment. First, the impact factors that can be secured through the sewer GIS DB in Seoul were derived, and the weight, sub-criteria, and impact score of each impact factor were determined and the consequence of failure was calculated by weight sum method. In addition, the probability of failure was calculated by dividing the service life by the estimated useful life, and the consequence of failure and the probability of failure were classified into five grades by the Jenks natural breaks classification method. The prioritization method was applied to sub-catchment in the Seoul to derive a risk matrix and a risk grade. As a result, 26% of all subjects were selected as the inspection priority subjects with 4-5 risk grade. Therefore, using the risk-based CCTV prioritization methodology, it will be possible to systematically determine the objects that need investigation first.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.163-176
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• 2007

Landslides which is one of the major natural hazard is defined as a mass movement of weathered material rock and debris due to gravity and can be triggered by complex mechanism. It causes enormous property damages and losses of human lift directly and indirectly. In order to mitigate landslide risk effectively, a new method is required to develope for better understanding of landslide risk based on the damaged cost produce, investment priority data, etc. In this study, we suggest a new evaluation method for slope stability using risk analysis. 30 slopes including 10 stable slopes, 10 slopes of possible failure and 10 failed slopes along the national and local roads are examined. Risk analysis comprises the hazard analysis and the consequence analysis. Risk scores evaluated by risk analysis show very clear boundaries for each category and are the highest for the failed slopes and the lowest for the stable slopes. The evaluation method for slope stability suggested by this research may define the condition and stability of slope more clearly than other methods suggested by others.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.627-635
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• 2017

Brachytherapy is generally performed in conjunction with external radiation therapy, and the treatment course is very complicated, which can lead to radiation accidents. In order to solve this problem, we designed the process map by applying the failure mode and effects analysis (FMEA) method to the Brachytherapy and scored the risk priority number (RPN) for each treatment course based on this process map. The process map consisted of five steps, Patient consulting", "Brachytherapy simulation", "CT simulation", "Brachytherapy treatment planning" and "Treatment". In order to calculate the RPN, doctor, medical physicist, dose planners, therapist, and nurse participated in the study and evaluated occurrence, severity, and lack of detectability at each detail step. Overall, the process map is preceded by a patient identification procedure at each treatment stage, which can be mistaken for another patient, and a different treatment plan may be established to cause a radiation accident. As a result of evaluating the RPN for the detailed steps based on the process map, overall "Patient consulting" and "Brachytherapy treatment planning" step were evaluated as high risk. The nurses showed a tendency to be different from each other, and the nurses had a risk of 55 points or more for all the procedures except "Treatment", and the "Brachytherapy simulation" step was the highest with 88.8 points. Since the treatment stage differs somewhat for each medical institution performing radiotherapy, it is thought that the risk management should be performed intensively by preparing the process map for each institution and calculating the risk RPN.

• Fire Science and Engineering
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• v.33 no.6
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• pp.87-94
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• 2019

Through a press release dated July 17, 2018, the Anti-Corruption and Civil Rights Commission recommended that the National Fire Agency develop preventive measures against fire in the "Indoor Archery Ground" and "Room Escape Café" etc., which were originally excluded from the category of "Publicly Used Establishments." This study developed the hierarchy of domains and indicators of measurement for fire risk assessment of the new business of publicly used establishments through the Delphi Method. It analyzed the goodness of fit scores (over 3.00) and secured an average score of 4.25. Using AHP analysis, the ratio of consistency for the domains of measurement of fire risk assessment was found to be 4.0%, which was lower than CR ≤ 0.1 (10%). The consistency of subsequent measurement indicators were distributed in the range of 0.1%~3.6%, and they were identified as being commonly consistent. The indicators of measurement appeared as follows in order of importance and priority: Type of Internal Passage of Establishment and Evacuation Capacity of Exit (0.316), Control of Ignition Source (0.141), Inherent Risk (0.106), Appropriateness and Adaptiveness of Fire Detection System (0.097), Control of Inflammables/Combustibles (0.084), Guides and Facilities helping Evacuation (0.075), Fire Resistant Structure and Finishing Materials (0.060), Compartmentalization and Emergency Exit (0.049), Risk of Fire Expansion (0.046), and Appropriateness and Adaptiveness of Fire Extinguishing Facilities (0.026). The findings of this study are expected to be expansively used as data for future research on the development of fire risk assessment indicators.

• Korean Journal of Construction Engineering and Management
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• v.13 no.3
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• pp.14-24
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• 2012

Recently, a delivery system has been rapidly changed in the global construction market. Also, construction projects are becoming bigger and more technology-intensive. A lot of projects have been delivered by Design-Build(DB) System; from the standpoint of cost, approximately 40% of delivered constructions by a Public Procurement Service were DB in 2009. Nevertheless, the achievement has not surpassed our expectations on management of the project cost. On the characteristic of DB, the reasons why that happens are that projects contract have been signed after the Design Development Stage; the insufficient review about new technology and up-to-date construction methods; a lack of discussion in process of design. Those reasons cause a risk of increasing Cost of the projects. In order to solve these problems, it is desirable to find Cost-increasing factors in promoting the projects and select on the order of priority for Risk-Factor with careful management. Therefore, this study analyzed the weight of each phase of the project on the authority of properties of DB project, and identified Risk-factors which is increasing the cost on the aspect of project management. Based on this analysis, the impact assessment of Risk-factor is evaluated through the Failure Mode and Effect Analysis(FMEA).

• Journal of the Korean GEO-environmental Society
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• v.21 no.10
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• pp.11-16
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• 2020

Korea's agricultural reservoir is one of the country's major infrastructures and plays an important role in people's lives. However, aging reservoirs are a risk for life and property. Currently, large and small dams and reservoirs have been constructed nationwide for more than 40 years of aging. Dams and reservoirs built nationwide are managed by various institutions. Therefore, it is difficult to manage all dams and reservoirs due to cost and time. Managers in the field with less management personnel and lack of expertise should be able to quickly identify risk factors for multiple reservoirs. In this study, risk factors such as seepage, leakage, settlement slide, crack and erosion were selected. To assess the risk of the items, we used the analytical hierarchical process (AHP), one of the Multi-Criteria Decision Making (MCDM) methods. The analysis showed that seepage has the greatest impact on reservoir collapse. It is judged that the priority of detailed diagnosis can be determined by evaluating the risk of dam reservoir collapse in a convenient way in advance using the calculated weight.