• 품질경영학회지
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• 제29권2호
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• pp.46-53
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• 2001

In this paper, a preventive maintenance(PM) policy for a repairable system is considered. The failure rate model proposed by Park et at.(2000) is generalized by assuming that after each PM not only the PM slows down the degradation process of the system but also reduces down the system failure rate by a certain fixed amount. Long-run expected cost rate of the PM policy is derived and the properties of joint solution of the optimal PM period and optimal number of PM which minimizes the expected cost rate are obtained. Numerical examples for the case of a Weibull-type failure rate are given.

• 대한안전경영과학회지
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• 제19권3호
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• pp.89-95
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• 2017

This paper presents another maintenance policy for a group of units under finite operating horizon. A group of identical units are subject to random failures. Group maintenances are performed to all units together at specified intervals, and the failed units during operation are remained idle until the next group maintenance set-up. Unlike the traditional assumption of infinite operating horizon, we adopt the assumption of the finite operating horizon which reflect the rapid industrial advance and short life cycle of modern times. The units are under operation until the end of the operating horizon. Further, the operation of units are extended to the first group maintenance time after the end of the horizon. The total cost under the proposed maintenance policy is derived. The optimal group maintenance interval and the expected number of group maintenances during the horizon are found. It is shown that the proposed policy is better than the classical group maintenance policy in terms of total cost over the operating horizon. Numerical examples are presented for illustrations.

• 품질경영학회지
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• 제51권2호
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• pp.315-327
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• 2023

Purpose: Recently, research has continued to predict the time of failure of the facility through measurement data obtained by attaching a sensor to the facility. However, depending on the facility, it may be difficult to attach a sensor. The purpose of this study is to propose a power generation maintenance plan system based on failure record data obtained from Continuous Ship Unloader, one of the facilities that is difficult to attach sensors. Methods: This study uses data collected from 2012 to 2022 from the 'CSU-1B' model among Continuous Ship Unloader operated by Korea Midland Power Co., LTD. By fitting fault record data to the Weibull distribution, appropriate maintenance cycles and ranges for each target facility subsystem are derived. In addition, maintenance group between subsystems is selected through Euclidean distance, a metric often used for time series data similarity. Through this, a system for establishing an maintenance plan for power generation facilities is proposed. Results: The results of this study are as follows. For the 17 subsystems of the Continuous Ship Unloader, proper maintenance cycles and ranges were determined, and a total of four maintenance groups were chosen. This resulted in the creation of an power generation maintenance plan system and the establishment of an maintenance plan. Conclusion: This study is a case study of power generation facilities. We proposed a maintenance plan system for Continuous Ship Unloader among power generation facilities.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.600-605
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• 2004

The road construction with horizontal expansion of country using and augmentation of traffic demand is advanced actively and it accompanies hereupon, the above of 70% of the country is formed at the mountain in our country where the hazard cut slope has been created. In this study, It is prepared a effective management countermeasure of cut slope introduced priority investigation decision method against hazard cut slope which is influenced by abnormally rainfall by an unusual change in the weather such as a guerilla rainfall character. In meaning link, It was executed collapse cause by failure character analysis in the cut slope which has failed for the last five years and it is prepared the hazard grade criterion from E to A grade according to collapse cause. It is decided that a maintenance management grade by the hazard grade classification criterion of cut slope. So It is possible to hazard cut slope. It is established failure protection counter countermeasure by effective maintenance management through the hazard grade c1assification criterion and it will be able to dispose to advanced nation level like Hong Kong and Japanese.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.372-378
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• 2018

Life management technology is required as the failure risk of aged power transformers increases. Asset management technology is developed to evaluate the remaining life, establish the replacement strategies, and decide the optimal investment based on the reliability and economy of power transformers. The remaining life assessment uses data such as installation, operation, maintenance, refurbishment, and failure of power transformers. The optimal investment also uses data such as maintenance, outage, and social costs. To develop the asset management system for power transformers, determining the degradation parameters related to the aging of power transformers and evaluating the condition of power transformers using these parameters are important. In this study, since 1983, 110,000 Dissolved Gas Analysis (DGA) data have been analyzed to determine the degradation parameters related to the aging of power transformers. The alarm rates of combustible gases ($H_2$, $C_2H_2$, $C_2H_4$, $CH_4$, and $C_2H_6$), TCG, CO, and $CO_2$ were analyzed. The end of life and failure rate (bathtub curve) of power transformers were also calculated based on the failure data from 1981 to 2014. The DGA gases related to discharge, overheating, and insulation degradation were determined based on alarm and failure rates. $C_2H_2$, $C_2H_6$, and $CO_2$ were discharge, oxidation, and insulation degradation parameters related to the aging of power transformers.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2845-2849
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• 2008

Long Term Asset Management(LTAM) means a plan developed by using LCM(Life Cycle Management) process for optimum life cycle management of significant plant assets at each plant across the fleet. As a part of development of LTAM Strategies on nuclear turbines, a method so as to determine the future failure rates for low pressure turbine facilities at a nuclear plant was studied and developed by using both plant specific and industry-wide performance data. INPO's EPIX data were analyzed and some failure rate evaluation values considering preventive maintenance practices were calculated by using EPRI's PM Basis software. As the result, failure rate functions applicable to a priori and a posteriori replacement of low pressure turbines at a nuclear plant were developed and utilized in an assessment of economics of LCM alternatives on the nuclear turbine facilities in the respects of 40-year and 60-year operation bases.

• 한국가스학회지
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• 제20권5호
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• pp.57-63
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• 2016

밸브는 설비 및 시스템의 제어를 위한 필수 요소로써 필수부품이지만 사용 중 Stem에서부터 볼까지의 연결부 유격으로 인한 개폐 불량이 발생할 수 있으며 이물질 유입, 마모, 크랙, 스크래치, 고착, 작동불량 등으로 인하여 사고로까지 이어질 수 있다. 사례 조사 결과 밸브의 고장 원인은 64%가 기밀누설이나 작동불량이었으며, 대부분의 밸브 누출 폭발사고는 설치현장에서 밸브 고착 등 작동불량을 해소하는 과정에서 발생했다. 이는 안전관리와 유지관리에 대한 시스템이 미비하고 안전밸브를 제외한 산업용 밸브의 유지관리 의무화가 되는 법규가 없어 권장사항과 유지관리 업체의 재량에 맡기고 있는 실정이기 때문이다. 따라서 철저한 유지관리로 위험요인을 제거하고 누출 사고 발생 시 피해의 최소화를 위해 초동대처방안이 마련되어야 한다. 본 연구에서는 산업현장에서 밸브의 사용 현황과 유지관리현황을 조사하고 밸브 모니터링을 통한 안전성 향상 방안을 제시하였다. 밸브상태진단 및 운영조회, 가스누출상시감시, 밸브 유지관리 비용절감, 전주기 수명관리 등의 효과를 갖는 모니터링 시스템 구축으로 가스안전관리 고도화에 기여할 수 있을 것이다.

• International Journal of Railway
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• 제3권1호
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• pp.34-37
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• 2010

In recent, the railway system consists of subsystems as rolling stock and infrastructures as signaling, telecommunication, power supply, overhead contact and platform screen door, etc. Furthermore, each subsystem has complicated interface so as not to understand these relationship. Consequently, to operate the railway system continuously with required safety and availability, the failure data should be corrected and analyzed systematically during operation. To achieve this object effectively, this paper presents the method which is evaluating the operational risk quantitatively using failure data, and selecting the critical equipment. Following this analysis, the improvement plan is established and applied to reduce the operational risk on system or equipment. From this study, the critical equipments of system could be determined and prioritized by risk analysis. Also, the effective maintenance to prevent critical failure could be implanted by this suggested methodology.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제23권1호
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• pp.1-12
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• 2017

예방정비는 대규모 산업시설에서 설비의 성능을 최적으로 유지하는 활동을 의미하며, 궁극적으로 고장을 미연에 방지하여 생산 효율을 극대화하는 것을 목적으로 한다. 일반적으로 인력에 의한 주기적인 정비가 이루어지지만, 지속적으로 발생하는 고장을 방지할 수 없는 문제가 있다. 또한, 문제를 조기에 해결하기 위한 고장에 대한 조치는 설비 전문가에 의존하기 때문에, 전문가의 부재 상황이나 미숙련된 전문가에 의한 진단 오류로 인한 대응의 한계가 있다. 인력에 의존한 설비 진단과 문제의 조기 발견을 돕기위해 알람 시스템이 활용되고 있지만, 단순 정보 수집을 위해 설계되고, 방대하게 알람을 발생시키므로 실제적인 효용성이 없다. 본 논문에서는 시스템에 의한 고장징후 포착과 문제의 원인 및 향후 발생할 문제를 파악하기 위해서, 전문가의 경험지식을 시스템 지식으로 구축을 통한 자동화된 예방정비시스템을 설계 및 개발하였으며, 전문가 지식을 재이용하기 위한 시스템의 구조와 활용 방안에 대해서 논한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.711-712
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• 2011