• Structural Engineering and Mechanics
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• 제64권3호
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• pp.347-352
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• 2017

The poor maintenance practice increases the possibility of system failure. Subsequently, the consequences of failure fall on the aspects of output, safety and healthy, environmental integrity, system quality, and customer satisfaction. Conditionbased maintenance is seen as a potential strategy to improve performance. Whereby, the key success factor of this maintenance strategy is identified as the system inspection. This study aims to investigate the association between system breakdown rate and frequency of inspection. A mixed method approach is implemented by distributing questionnaire and interviewing for data collection. Subsequently, descriptive analysis, correlation analysis and regression are adopted to analyse the collected data from 100 respondents and the results are validated with interview data of 10 interviewees. The research result establishes significant relationship between the system breakdown rate and the frequency of inspection. Additionally, the result of regression analysis confirms that the frequency of inspection is the significant predictor of system breakdown rate. Planning of accurate inspection frequency is crucial to secure the system performance. Hence, the research signifies the importance to carry out regular inspection towards the building systems and components. As a recommendation, the maintenance personnel should assess the risk criticality of the building systems. Then, continuously monitor the condition of critical building systems; regularly inspect the condition of non-critical building systems and randomly inspect all of them.

• Safety and Health at Work
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• 제9권1호
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• pp.42-52
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• 2018

Background: Maintenance operations on-board ships are highly demanding. Maintenance operations are intensive activities requiring high man-machine interactions in challenging and evolving conditions. The evolving conditions are weather conditions, workplace temperature, ship motion, noise and vibration, and workload and stress. For example, extreme weather condition affects seafarers' performance, increasing the chances of error, and, consequently, can cause injuries or fatalities to personnel. An effective human error probability model is required to better manage maintenance on-board ships. The developed model would assist in developing and maintaining effective risk management protocols. Thus, the objective of this study is to develop a human error probability model considering various internal and external factors affecting seafarers' performance. Methods: The human error probability model is developed using probability theory applied to Bayesian network. The model is tested using the data received through the developed questionnaire survey of >200 experienced seafarers with >5 years of experience. The model developed in this study is used to find out the reliability of human performance on particular maintenance activities. Results: The developed methodology is tested on the maintenance of marine engine's cooling water pump for engine department and anchor windlass for deck department. In the considered case studies, human error probabilities are estimated in various scenarios and the results are compared between the scenarios and the different seafarer categories. The results of the case studies for both departments are also compared. Conclusion: The developed model is effective in assessing human error probabilities. These probabilities would get dynamically updated as and when new information is available on changes in either internal (i.e., training, experience, and fatigue) or external (i.e., environmental and operational conditions such as weather conditions, workplace temperature, ship motion, noise and vibration, and workload and stress) factors.

• 대한토목학회논문집
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• 제28권2A호
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• pp.223-231
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• 2008

이 논문에서는 교량의 유지보수비용을 최소화할 뿐만 아니라 교량의 성능을 동시에 최대화할 수 있는 새로운 유지보수계획법을 제시한다. 교량 수명연한 동안의 유지보수비용과 교량의 바닥판, 주형, 하부구조의 상태등급으로 표현되는 교량의 성능을 동시에 최적화 하는 다목적 최적화 문제를 구성하여 최적의 유지보수계획을 수립한다. 다목적 최적화문제의 해를 얻기 위한 수치해석 방법으로 유전자 알고리즘(Genetic Algorithm, GA)을 사용하고, 다목적 최적화방법을 적용하여 얻어진 여러 개의 해집합 중 최적해의 선택을 위한 의사결정(decision making)을 위해 선호도기반 최적화방법을 적용한다. 일반적인 5경간의 PSC I형 교량에 대한 수치예제를 통해, 이 연구에서 제안하는 방법이 유지보수비용 및 교량성능간의 균형 있는 최적화를 이룰 수 있음을 보인다.

• 산업경영시스템학회지
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• 제22권53호
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• pp.45-54
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• 1999

Manufacturing today is becoming increasingly competitive. If a company is to exist and successfully compete, it must pay very careful attention to production management, total quality assurance and total proactive maintenance issues. Overall machine performance, repair efficiency, system level utilization, productivity and quality of output need to be optimized as possible. To accomplish that objective, the behavior of manufacturing equipment and systems need to be monitored and measured continuously if it is possible. Then early warning of possible failure should be generated and proacted on that type of the situation to improve overall operation performance of manufacturing environment. In this paper, Proactive maintenance framework using performance-based reliability structure as enabler technology is proposed. Its paradigm enables one to maximize system through-put and product quality as well as resources in the performance domain. In the case of inadequate knowledge of the failure mechanics, this empirical modeling concept along with performance degradation knowledge can serve as an important product and process improvement tool. The real-time framework extension to proposed framework uses on-line performance information and is capable of projecting the remaining useful period.

• 경영과정보연구
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• 제30권4호
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• pp.415-440
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• 2011

본 연구의 목적은 국내 중소기업에 있어서 전사적 생산 설비 보전(TPM: Total Productive Maintenance)활동이 기업의 경영성과에 어떠한 영향을 미치는지를 실증적으로 규명하는 것이다. 그 결과 개별개선, 자주보전활동을 통하여 경영관점, 고객관점, 성과관점, 그리고 활동관점 등 4가지 관점의 성과를 제고할 수 있는 것으로 나타났다. 또한 계획보전, 교육훈련, 안전환경활동은 고객관점, 성과관점, 그리고 활동관점의 경영성과를 향상시킬 수 있는 것으로 확인되었다. 따라서 본 연구 결과 TPM을 도입한 기업이 전사적 차원에서 체계적인 생산보전활동을 수행함으로써 기업의 경영성과에 긍정적인 영향을 미치는 것으로 나타났으므로 우리나라 기업들이 TPM을 도입 추진하여 지속적으로 활용해야 할 당위성과 필요성을 제시해 준 연구라고 할 수 있다. 또한 4가지 관점에서의 성과측정을 통해 TPM 추진 기업에서의 성과측정지표 선정시 추진목적에 따라 어느 관점에서 중점적으로 성과목표를 설정하여야 할 것인가에 대한 가이드라인 역할뿐만 아니라 향후 TPM 성과 관련 후속연구의 기본방향을 제시해준 연구라고 할 수 있다. 그리고 본 연구의 실증분석에서 도출된 TPM 활동요인과 성과측정 지표의 체계적인 관리를 통해 TPM활동을 보다 효과적으로 추진함으로써 중소기업의 경영성과 및 기업경쟁력을 높이는데 기여할 수 있다고 본다.

• 산업경영시스템학회지
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• 제42권4호
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• pp.145-152
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• 2019

All machines deteriorate in performance over time. The phenomenon that causes such performance degradation is called deterioration. Due to the deterioration, the process mean of the machine shifts, process variance increases due to the expansion of separate interval, and the failure rate of the machine increases. The maintenance model is a matter of determining the timing of preventive maintenance that minimizes the total cost per wear between the relation to the increasing production cost and the decreasing maintenance cost. The essential requirement of this model is that the preventive maintenance cost is less than the failure maintenance cost. In the process mean shift model, determining the resetting timing due to increasing production costs is the same as the maintenance model. In determining the timing of machine adjustments, there are two differences between the models. First, the process mean shift model excludes failure from the model. This model is limited to the period during the operation of the machine. Second, in the maintenance model, the production cost is set as a general function of the operating time. But in the process mean shift model, the production cost is set as a probability functions associated with the product. In the production system, the maintenance cost of the equipment and the production cost due to the non-confirming items and the quality loss cost are always occurring simultaneously. So it is reasonable that the failure and process mean shift should be dealt with at the same time in determining the maintenance time. This study proposes a model that integrates both of them. In order to reflect the actual production system more accurately, this integrated model includes the items of process variance function and the loss function according to wear level.

• 대한기계학회논문집 C: 기술과 교육
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• 제2권2호
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• pp.81-87
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• 2014

자동차정비직무의 "일과 학습의 연계"를 위해 현장에서 필요한 직무수행능력을 기준으로 자동 차정비 분야에 대한 교육훈련과 자격기준으로 활용할 수 있도록 자동차정비 현장전문가들이 국가직무 능력표준(NCS: National Competency Standards)을 개발하였다. 본 연구를 통하여 자동차정비직무의 국가 직무능력표준 개발영역과 직무체계를 수립하였고 직무능력단위별 수행준거, 지식, 기술, 태도 및 평가방법을 제시하였다. 또한 자동차정비직무의 능력단위별 직업기초능력의 영역별 수준을 제시하였으며 자격기준안을 제시하여 교육과 평가의 기준을 마련하였다.

• 산업경영시스템학회지
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• 제21권48호
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• pp.279-289
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• 1998

This study deals with the schemes of design, plan and operate maintenance management support systems and with the engineering approach for the solutions to build the maintenance management for the production efficiency. Maintenance Management Information System(MMIS) is the task that must focus on machinery historical data and planned maintenance action. Also the efficient supporting system in a maintenance management is achieved by database which is based on process of machinery's failure history. Designing method of maintenance management information system, maintenance modules are consisted of six factors ; machinery's historical data, lubrication control, check sheet, repair work, availability report, and performance report(control board and detailed reports), and then operators can rapidly utilize data in work place. In the implementation of designed model, program coding has been developed by Visual Basic 3.0. Data insertion, deletion and updating which perform menu screen is implemented by reading data from database. Implementation model based on LAN environment and related data is stored in Microsoft DBMS.

• 항공우주시스템공학회지
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• 제10권2호
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• pp.27-33
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• 2016

For the continued airworthiness of aviation products, aviation authority requires that every manufacturer should provide ICA(Instruction of Continued Airworthiness) to their users, and the users should follow it by themselves or using another approved maintenance agent. To reduce the cost and improve performance quality of maintenance activities, lots of users tries to outsource this job. To perform maintenance or repair of other owned air products, an air carrier and aviation maintenance companies should obtain AMO(approval of maintenance organization). It means AMO is a postulation to enter MRO(Maintenance Repair and Overhaul) market. For that, this paper discusses the comparison of requirements and procedures of AMO system between Korea and US to help understand the AMO system, and then, tries to point out what improvement should be made to Korean AMO system to be more effective, efficient and safe.

• International Journal of Reliability and Applications
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• 제11권2호
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• pp.123-138
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• 2010

This paper investigates a mathematical model of a system composed of two non-identical unit parallel system with common-cause failure, critical human error, non-critical human error, preventive maintenance and two type of repair, i.e. cheaper and costlier. This system goes for preventive maintenance at random epochs. We assume that the failure, repair and maintenance times are independent random variables. The failure rates, repair rates and preventive maintenance rate are constant for each unit. The system is analyzed by using the graphical evaluation and review technique (GERT) to obtain various related measures and we study the effect of the preventive maintenance preventive maintenance on the system performance. Certain important results have been derived as special cases. The plots for the mean time to system failure and the steady-state availability A(${\infty}$) of the system are drawn for different parametric values.