• Journal of Korean Society for Quality Management
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• v.44 no.2
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• pp.373-388
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• 2016

Purpose: This paper suggests a hierarchical time delay model to evaluate failure risks in FMEA(failure modes and effects analysis). In place of the conventional RPN(risk priority number), a more reasonable and objective risk metric is proposed under hierarchical failure cause structure considering time delay between a failure mode and its causes. Methods: The structure of failure modes and their corresponding causes are analyzed together with the time gaps between occurrences of causes and failures. Assuming the severity of a failure depends on the length of the delayed time for corrective action, a severity model is developed. Using the expected severity, a risk priority metric is defined. Results: For linear and quadratic types of severity, nice forms of expected severity are derived and a meaningful metric for risk evaluation is defined. Conclusion: The suggested REM(risk evaluation metric) provides a more reasonable and objective risk measure than the conventional RPN for FMEA.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.1
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• pp.177-186
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• 2014

Failure mode and effect analysis (FMEA) is a systematic approach for identifying potential failures before they occur, with the intent to minimize the risk associated with them. It has been widely used in the various manufacturing industries as a solution to reliability problems. As the importance of the service sector is increasing, however, it has been recently extended to some applications in services. Despite these attempts, FMEA cannot be directly applied to the reliability problems in a service industry. Due to the heterogeneity and customer participation in service process, we cannot perfectly prevent service failures. For this reason, we suggest a new risk priority number with three input parameters that consist of severity, probability of occurrence, and recoverability. In this paper, we propose an approach for assessing service risk and service reliability using the service-oriented risk priority number (S-RPN). An example regarding a hypermarket service process is used to demonstrate the proposed approach.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.7-15
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• 2019

This paper proposes the FMEA-based model to avoid backdoor transactions when purchasers select suppliers for products and services. In the model, backdoor transactions consist of two categories: backdoor selling and maverick buying. Both of which influence negative effects on cost savings due to not only uncompetitive advantage but also unusable purchasing leverage by unethical and misbehavior of purchase requestors. For the risk evaluation based on FMEA, three and five risk types of backdoor selling and maverick buying are identified respectively. Current risk priority numbers(RPN) based on those risk types are calculated by three categories: occurrence, detection and severity. Six risk mitigation strategies and fourteen mitigation tactics are identified to improve current RPN. In order to validate the model, questionnaires are collected from fifteen companies and statistically analyzed. The analysis result shows that the model reduces backdoor transaction risks and has no differences in reduction of backdoor transaction risks regardless of the type of purchasing organization units and existence of purchasing procedures in the organization.

• Journal of Korean Society for Quality Management
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• v.35 no.1
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• pp.1-9
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• 2007

Failure mode and effects analysis (FMEA) is a widely used technique to assess or to improve reliability of products at early stage of design and development. Traditionally, the prioritization of failures for corrective actions is performed by developing a risk priority number (RPN). In practice, due to insufficient evaluation criteria specific to related product and processes, RPN is not properly evaluated. This paper reestablishes an effective methodology for prioritization of failure modes in FMEA procedure. Revised evaluation criteria of RPN are devised and a refined FMEA sheet is Introduced. To verify the proposed methodology, it is applied to RPN evaluation for motors in household appliances.

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.7-15
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• 2016

The purpose of this paper is to carry out Failure Modes and Effects Analysis (FMEA) and use criticality in order to determine risk priority number of the components of electric power installations in Engineering college building of D university. In risk priority number, GROUP A had 7 failure modes; more specifically, Transfomer had 4 modes, Filter(C)(1 mode), LA(1 mode), and CB(MCCB)(1 mode), and thus 4 components had failure modes. In terms of criticality, high-grade group a total of 16 failure modes, and 7 components-LA(1 mode), CB(MCCB)(1 mode), MOF(2 modes), PT(1 mode), Transformer(7 modes), Cable(3 modes), and Filter(C)(1 mode)-had failure modes. Comparison of risk priority number and criticality was made. The components which had high risk priority number and high criticality were Transformer, Filter(C), LA, and CB(MCCB). The components which had high criticality were MOF and cable. In particular, Transformer(RPN: 4 modes, Criticality: 7 modes) was chosen as an intensive management component.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.65-72
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• 2020

In this study, the purpose is to identify the risks of the facilities of packaged hydrogen stations. As a risk identification method, failure mode & effect analysis (FMEA), a qualitative risk assessment, was used to analyze failure mode and effects of component of each facility. The analysis criteria were used to derive the risk priority number (RPN) using the 5-point method according to severity, incidence, and detectability. The study analyzed a total of 141 components of 23 types that can be identified on the design of the packaged hydrogen filling station. As a result, 683 types of failures and their causes and effects were identified. and the RPN was number of a total of 1,485. Of these, 10 failure types with a RPN value of 40 or more were deemed necessary. In addition, a list of failure types with a severity score of 5 was identified and analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.751-758
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• 2021

Munitions must be analyzed to identify any risks for quality assurance in development and mass production. Risk identification for parts, compositions, and systems is carried out through failure mode effects analysis (FMEA) as one of the most reliable methods. FMEA is a design tool for the failure mode of risk identification and relies on the RPN (risk priority number). FMEA has disadvantages because its severity, occurrence, and detectability are rated at the same level. Fuzzy FMEA applies fuzzy logic to compensate for the shortcomings of FMEA. The fuzzy logic of Fuzzy FMEA is to express uncertainties about the phenomenon and provides quantitative values. In this paper, Fuzzy FMEA is applied to the failure mode of a rotorcraft landing system. The Fuzzy rule and membership functions were conducted in the Fuzzy model to study the RPN in the failure mode of a landing system. This method was selected to demonstrate crisp values of severity, occurrence, and detectability. In addition, the RPN was obtained. The results of Fuzzy FMEA for the landing system were analyzed for the RPN and ranking by fuzzy logic. Finally, Fuzzy FMEA confirmed that it could use the data in quality assurance activities for rotorcraft.

• Journal of Energy Engineering
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• v.28 no.3
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• pp.10-17
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• 2019

According to South Korea's policy of supplying eco-friendly hydrogen vehicles, related industries are actively conducting research on the development of hydrogen cars and hydrogen charging station infrastructure. On the other hand, there is a lack of empirical research and assessment of the risk of non-metallic materials (such as liners, seals, gaskets) for classified materials that directly affect the durability and reliability of hydrogen vehicles and hydrogen charging stations. In this study, the risk factors for liners and seals of non-metallic parts used in high-pressure hydrogen installations were derived using FMEA, and the RPN values were calculated by converting the severity, frequency of occurrence and degree of detection into scores. The maximum value of the RPN 600, minimum value 63, average value 278.5 was calculated and periodic control of the liner and seal was identified as important. In addition, through hydrogen soakage and oxygen aging tests for non-metallic rubber products, physical test values that can be used as basic data were presented.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.30-35
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• 2003

Product liability(PL) law imposes the liability on manufacturer or wholesaler when the product defects cause harm to consumers of the products or any other parties in their lives, bodies, or properties. In Korea, the law of product liability was enforced in July 2002. In this study the Product Liability Response System of chemical products was developed by using Failure Mode and Effect Analysis(FMEA). For a case study peformed for N,N-Dimethylethylamine. First, product information was gathered through Material Safety Data Sheet(MSDS)and which considered as an instruction manual of chemical product. And an effect caused by product defects is analyzed by FMEA to get Risk Priority Number(RPN) which is calculated by multiplying of severity, occurrence, and detection of the defects. Then hazard was estimated quantitatively by RPN.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.45-51
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• 2009

A safety assessment was performed through the process analysis of hydrogen station. The purpose of this study provides basic information for the standard establishment about hydrogen stations. The processes of hydrogen stations were classified by four steps (process of manufacture, compression, storage, charge). FMEA (Failure Mode and Effect Analysis) method was applied to evaluate safety. Each risk element is following; S (severity), O (occurrence), D (detection). And the priority of order was decided by using RPN (Risk Priority Number) value multiplying three factors. Scenarios were generated based on FMEA results. And consequence analysis was practiced using PHAST program. In the result of C.A, jet fire and explosion were shown as accident types. In case of leakage of feed line in PSA process, concentration of CO gas is considered to prevent CO gas poisoning when the raw material that can product CO gas was used.