• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4408-4425
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• 2023

Alarm flood due to abnormality propagation is the most difficult alarm overloading problem in nuclear power plants (NPPs). Root-cause analysis is suggested to help operators in understand emergency events and plant status. Multilevel Flow Modeling (MFM) has been extensively applied in alarm management by virtue of the capability of explaining causal dependencies among alarms. However, there has never been a technique that can identify the actual root cause for complex alarm situations. This paper presents an automated root-cause analysis system based on MFM. The causal reasoning algorithm is first applied to identify several possible root causes that can lead to massive alarms. A novel root-cause ranking algorithm can subsequently be used to isolate the most likely faults from the other root-cause candidates. The proposed method is validated on a pressurized water reactor (PWR) simulator at HAMMLAB. The results show that the actual root cause is accurately identified for every tested operating scenario. The automation of root-cause identification and ranking affords the opportunity of real-time alarm analysis. It is believed that the study can further improve the situation awareness of operators in the alarm flooding situation.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권1호
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• pp.71-77
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• 2016

Purpose: Root cause analysis (RCA) refers to any systematic process that identifies the causes that contribute to a focus event. The immediate cause of a focus event is often a symptom of underlying causes and may not truly identify the root causes that should be identified and addressed. Currently many RCA tools are available. Different investigators use different RCA tools on different issues. No standardized or commonly agreed way to analyse root causes exists. The purpose of this study is to propose the methodology of RCA process commonly useable for various issues. Methods: The methodology of RCA process is produced based on the hybrid RCA tools. The effectiveness assessment matrix of actions through the root cause candidates is presented. Results: No single RCA technique proposed has so far covered all necessary aspects. A hybrid approach which combines the best features of various techniques is proposed. The effectiveness assessment matrix helps us to identify the root cause to correct or eliminate system vulnerabilities effectively. Conclusion: This hybrid approach and effectiveness assessment matrix can provide guidance of RCA process across many industries and situations.

• Safety and Health at Work
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• 제12권4호
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• pp.505-510
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• 2021

Background: Factors related to root causes can cause commonly occurring accidents such as falls, slips, and jammed injuries. An important means of reducing the frequency of occupational accidents in small- to medium-sized enterprises (SMSEs) of South Korea is to perform intensity analysis of the root cause factors for accident prevention in the cause and effect model like decision models, epidemiological models, system models, human factors models, LCU (life change unit) models, and the domino theory. Especially intensity analysis in a robot system and smart technology as Industry 4.0 is very important in order to minimize the occupational accidents and fatal accident because of the complexity of accident factors. Methods: We have developed the modern cause and effect model that includes factors of root cause through statistical testing to minimize commonly occurring accidents and fatal accidents in SMSEs of South Korea and systematically proposed educational policies for accident prevention. Results: As a result, the consciousness factors among factors of root cause such as unconsciousness, disregard, ignorance, recklessness, and misjudgment had strong relationships with occupational accidents in South Korean SMSEs. Conclusion: We conclude that the educational policies necessary for minimizing these consciousness factors include continuous training procedures followed by periodic hands-on experience, along with perceptual and cognitive education related to occupational health and safety.

• Journal of Information Technology Applications and Management
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• 제24권4호
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• pp.71-92
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• 2017

Finding a root cause is an essential step to solving a complex problem. Some previous studies have used the Delphi method for gathering opinions about root causes from geographically dispersed experts. However, we assert that complicated problems such as an industry ecosystem would make a general type of the Delphi method less practical because of too much psychological burden on study participants. In this study we present a preliminary list-based Delphi study method for identifying a root cause. This method was used to identify a root cause and draw a causal map for the information industry ecosystem problems.

• 보건의료산업학회지
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• 제13권3호
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• pp.13-26
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• 2019

Objectives: To investigate whether medical institutions can prevent accidents by analyzing the root cause of a medical accident and identifying the tendencies. Methods: A total of 345 medical cases were used for the RCA(Root Cause Analysis). The root causes were classified using the SHELL model. The suitability of the model was confirmed by SPSS's MDPREF and Euclidean distance. An SPSS20.0 hierarchical regression analysis was used as an influencing factor on the degree of injury resulting from medical accidents. Results: The SHELL model was suitable for classification. The rates of accident causes were LS49%, L34%, LL10.2%, LE3.7%, LH2.3%. The order in which the degree of a patient's injury was affected were: Risk Threshold (${\beta}=.180$), Time (${\beta}=.175$), Surgical stage (${\beta}=-.166$), Do not use procedure (${\beta}=.147$). Conclusions: Health care institutions should remove priorities through system improvement and training. For patients' safety, the five factors of the SHELL model should be managed in harmony.

• 한국가스학회지
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• 제4권4호
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• pp.65-70
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• 2000

본 연구에서는 국내 안전문화의 향상과 가스 관련 사고의 재발을 방지할 수 있으며, 사고 원인 분석의 원활한 수행을 도모할 수 있도록 기술적 지원을 할 수 있는 $\lceil$가스 사고 근본 원인 해석 시스템$\rfloor$을 개발하였다. 본 연구에서 개발한 프로그램은 가스산고 조사시사고원인을 체계적으로 분석할 수 있도록 사고사례를 분석하여 사고원인 데이터베이스를 구축하였으며, If${\~}$Then Rule을 적용하여 사고의 1차 원인을 찾을 수 있게 하였다. 이때 사고 발생장소, 사고 형태, 사고시 운전 상황, 사고 가스, 사고 발생 기계장치 및 구성요소들을 유기적으로 연결하여 도출되는 1차 원인의 수를 줄이도록 하였다. 또한, 인적 오류, 장치 결함, 외부 요인을 시작점으로 하여 5단계의 질의를 통하여 근본 원인을 찾아갈 수 있도록 하는 Root Cause Analysis Map을 구축하였다.

• 대한인간공학회지
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• 제34권2호
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• pp.103-113
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• 2015

Objective: This study proposes a systematic process to present the analysis methods and solutions of organizational root causes to human errors on the railroad. Background: In fact, organizational root cause such as organizational culture is an important factor in the safety concerns on human errors in the nuclear power plant, railroad and aircraft. Method: The proposed process is as follows: 1) define analysis boundary 2) select human error taxonomy 3) perform accident analysis 4) draw root causes with FGI 5) review root causes analysis with survey 6) chart analysis of root causes, and 7) propose alternatives and solutions. Results: As a result, root causes of the organizations like railroad and nuclear power plant came from the educational problems, violations, payoff system, safety culture and so forth. Conclusion: The proposed process does predict potential railroad accident through retrospect error analysis by building new human error taxonomies and problem solution. Application: This study would contribute to examination of the relationship between human error-based accidents and organizational root causes.

• 동력기계공학회지
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• 제12권4호
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• pp.57-63
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• 2008

The last stage blade of the low pressure steam turbine remarkably affects turbine plant performance and availability Turbine manufacturers are continuously developing the low pressure last stage blades using the latest technology in order to achieve higher reliability and improved efficiency. They tend to lengthen the last stage blade and apply shrouds at the blades to enhance turbine efficiency. The long blades increase the blade tip circumferential speed and water droplet erosion at shroud is anticipated. Parts of integral shrouds of the last stage 40 inch blades were cracked and liberated recently in a combined cycle power plant. In order to analyze the root cause of the last stage blades shroud cracks, we investigated operational history, heat balance diagram, damaged blades shape, fractured surface of damaged blades, microstructure examination and design data, etc. Root causes were analyzed as the improper material and design of the blade. Notches induced by erosion and blade shroud were failed eventually by high cycle fatigue. This paper describes the root cause analysis and countermeasures for the steam turbine last stage blade shroud cracks of the combined cycle power plant.

• 한국의료질향상학회지
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• 제23권1호
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• pp.25-38
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• 2017

Root cause analysis (RCA) is systematic process for identifying contributing factors and root causes. It detects system-level vulnerabilities and prevents them from occurring in the future. In many countries, RCA guidelines have been developed and used for these purposes, and various practical tools are suggested according to stages of RCA implementation. In Korea, adverse events occur in 7.2-8.3 percent of inpatients according to studies conducted in hospitals. However, frontline staffs are suffering from lack of knowledge about RCA implementation. This study introduces RCA guidelines that may be used in hospitals to improve the quality of medical care and patient safety.

• 한국철도학회논문집
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• 제13권4호
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• pp.455-461
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• 2010

본 연구에서는 철도운영 및 시설기관의 사고/장애 데이터를 분석하여 근본원인-사고원인-위험원에 대한 분류체계를 수립하였고, 사고유형, 사고원인, 위험원, 근본원인에 대한 패턴분석을 통해 주요 사고별로 사고에 영향을 미치는 원인이 무엇인지를 정확히 분석하여, 철도사고를 유발할 수 있는 위험원인를 근본적으로 차단하기 위해 사고원인분석 정보를 국가 및 철도운영기관 등이 활용함으로써 효율적인 철도안전정책을 수립할 수 있는 사고원인분석시스템을 개발하였다.