• 산업경영시스템학회지
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• 제41권2호
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• pp.24-31
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• 2018

As a system complexity increases and technology innovation progresses rapidly, leasing the equipment is considered as an important issue in many engineering areas. In practice, many engineering fields lease the equipment because it is an economical way to lease the equipment rather than to own the equipment. In addition, as the maintenance actions for the equipment are costly and need a specialist, the lessor is responsible for the maintenance actions in most leased contract. Hence, the lessor should establish the optimal maintenance strategy to minimize the maintenance cost. This paper proposes two periodic preventive maintenance policies for the leased equipment. The preventive maintenance action of policy 1 is performed with a periodic interval, in which their intervals are the same until the end of lease period. The other policy is to determine the periodic preventive maintenance interval minimizing total maintenance cost during the lease period. In addition, this paper presents two decision-making models to determine the preventive maintenance strategy for leased equipment based on the lessor's preference between the maintenance cost and the reliability at the end of lease period. The structural properties of the proposed decision-making model are investigated and algorithms to search the optimal maintenance policy that are satisfied by the lessor are provided. A numerical example is provided to illustrate the proposed model. The results show that a maintenance policy minimizing the maintenance cost is selected as a reasonable decision as the lease term becomes shorter. Moreover, the frequent preventive maintenance actions are performed when the minimal repair cost is higher than the preventive maintenance cost, resulting in higher maintenance cost.

• 산업공학
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• 제16권1호
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• pp.27-33
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• 2003

The maintenance cost in K Steelworks has been continuously increased in proportion to the production cost. However, there seems to be a possibility of reducing cost through the optimization of maintenance actions. The failure types of the equipment in steelworks ate various with different failure cost. Thus the failure rate and cost of each type of failures should be considered simultaneously when the optimum maintenance period is to be determined. It is considered that the equipment undergoes periodic replacement and a specified number of incomplete preventive maintenance actions are performed during a replacement period. Assuming that the time to failure follows a Weibull distribution, the parameters of the failure rate are estimated using the maximum likelihood estimation. The optimal replacement period is determined to minimize the average cost per unit time. As the result of analysis it is suggested that the existing maintenance period for a hot-rolling equipment can be extended significantly.

• 한국국방경영분석학회지
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• 제34권3호
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• pp.41-51
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• 2008

현대전에 있어서 첨단 정밀 고가장비가 전투력에 미치는 영향은 지대하다. 그러나 평상시 지속적인 정비활동이 이루어지지 않으면 장비가동률은 저하되고 유사시 목표하는 전투력 발휘효과는 기대하기 어려울 것이다. 따라서 적정 장비유지비 소요를 예측하여 예산에 반영하는 것은 전투준비태세 완비를 위해서 필수적인 과제라 하겠다. 본 연구에서는 K-111 1/4톤 기동장비의 야전 운영 실적자료를 분석하여 장비유지비 발생추세를 분석하고, 이 분석 결과를 기초로 장비유지비 예측모델을 설계하였으며, 이 예측모델을 적용하여 장비유지비 소요 예측 기법과 향후 발전 방향에 대한 제언을 제시하였다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.503-508
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• 2007

건설공사 표준품셈 기계경비 부분은 1960년대 초 일본 및 미국의 자료를 근간으로 하여 제정된 이후, 극히 부분적으로만 제 ${\cdot}$ 개정되었을 뿐 그 동안의 건설기계와 공법의 발전을 반영하지 못하고 있다. 본 연구에서는 표준품셈 기계경비 중에서 기계손료의 관리비(금리, 격납보관비, 보험료, 세금)를 조사하였으며 합리적인 관리비 산출을 위해 국내 ${\cdot}$ 외 문헌조사, 건설현장 16개소 실사, 그리고 건설기계장비 임대업체 20개사를 대상으로 설문조사 및 인터뷰를 실시하였다. 수집한 자료와 현행 표준품셈의 관리비 산출에 적용되는 수치들을 비교분석한 결과를 토대로 관리비를 새롭게 정의하였다. 관리비의 구성 면에서 금리, 격납보관비, 보험료와 세금 등을 고려하여 6종건설기계와 일반기계를 구분하였고 현실적인 수치를 제시하였다. 본 논문에서 제시하고 있는 각종 자료 및 수치들은 적정한 공사 예정가격을 산정할 수 있는 기초가 될 수 있을 뿐 아니라, 관련 연구의 토대가 될 수 있으리라 기대한다.

• 전기학회논문지P
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• 제58권4호
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• pp.410-415
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• 2009

With the implementation of electric power industry reform, the utilities are looking for effective ways to improve the economic efficiency. One area in particular, the equipment maintenance, is being scrutinized for reducing costs while keeping a reasonable level of the reliability in the overall system. Here the conventional RCM requires the tradeoff between the upfront maintenance costs and the potential costs of losing loads. In this paper we describe the issues related to applying so-called the "Reliability-centered Maintenance" (RCM) method in managing electric power distribution equipment. The RCM method is especially useful as it explicitly incorporates the cost-tradeoff of interest, i.e. the upfront maintenance costs and the potential interruption costs, in determining which equipment to be maintained and how often. In comparison, the "Time-based Maintenance" (TBM) method, the traditional method widely used, only takes the lifetime of equipment into consideration. In this paper, the modified Markov model for maintenance is developed. First, the existing Markov model for maintenance is explained and analyzed about transformer and circuit breaker, so on. Second, developed model is introduced and described. This model has two different points compared with existing model: TVFR and nonlinear customer interruption cost (CIC). That is, normal stage at the middle of bathtub curve has not CFR but the gradual increasing failure rate and the unit cost of CIC is increasing as the interruption time is increasing. The results of case studies represent the optimal maintenance interval to maintain the equipment with minimum costs. A numerical example is presented for illustration purposes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.742-743
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• 2007

A maintenance plan of power system equipment reduces failure rate caused by equipment's age. To prevent unexpected failure, the maintenance is performed periodically according to the interval time. The more expansive equipment's scale is, the more the maintenance without considering costs sustains a economical loss. Hence, the maintenance's time and the cost must be considered when maintenance which is considering the reliability is implemented. In this paper, optimum maintenance interval is calculated by considering minimum maintenance cost of the equipment with the combined cycle units in Korea power systems.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.624-631
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• 2022

Highway Rest Areas are envisioned to provide an accessible space for rest and parking for travelers, especially those driving a long distance. In addition, modern highway Rest Areas provide many amenities to highway users, including wifi service, picnic tables, litter barrels, running water, public telephones, and sometimes even free coffee. Various studies were conducted in the domain of Rest Area facility design and their operating costs in different states; however, limited studies were conducted on the maintenance costs of these facilities. Therefore, this study's main objective is to compute the annual maintenance cost of Rest Areas in the state of Nevada. This study also analyzes the main cost categories of the maintenance works. The raw cost data of Nevada Rest Area maintenance from 1990 to 2012 were collected from the Nevada Department of Transportation (NDOT). Results show that the maintenance cost fluctuated over the study period; the maintenance cost decreased from 1991 to 2004 and then increased until 2012. The primary cost categories of maintenance work are labor, equipment, and material costs. Among these, labor cost was the largest category with 56 percent of the total maintenance cost, followed by equipment cost and material cost. The findings of this study may help NDOT and other transportation agencies plan their budget for future Rest Area maintenance activities.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.224-230
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• 2016

Purpose: Military maintenance involves corrective and preventive actions carried out to keep a system in or restore it to a predetermined condition. This research develops an optimal maintenance cycle for aviation oil testing equipment with acceptable reliability level and minimum maintenance cost. Methods: The optimal maintenance policy in this research aims to satisfy the desired reliability level at the lowest cost. We assume that the failure process of equipment follows the power law non-homogeneous Poisson process model and the maintenance system is a minimal repair policy. Estimation and other statistical procedures (trend test and goodness of fit test) are given for this model. Results: With time varying failure rate, we developed reliability-based maintenance cost optimization model. This model will reduce the ownership cost through adopting a proactive reliability focused maintenance system. Conclusion: Based on the analysis, it is recommended to increase the current maintenance cycle by three times which is 0.5 year to 1.5 years. Because of the system's built-in self-checking features, it is not expected to have any problems of preventative maintenance cycle.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.153-162
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• 2017

무기체계는 기술의 발달로 인하여 급속도로 발전하고 있다. 이러한 발전덕분에 과거 무기체계에서 보지 못했던 고가의 첨단 전자장비들이 포함된 무기체계가 등장하게 되었다. 더불어, 고도의 기술이 적용된 무기체계의 운영 및 유지보수를 위한 장비유지예산 또한 증가되고 있다. 그러나 장비유지예산은 장비자산대비 그 비율이 감소추세에 있어, 효율적인 무기체계 운영에 어려움이 초래되고 있다. 이처럼 고비용 환경이 되고 있는 국방경영 및 감소되고 있는 장비유지예산을 고려하는 연구가 필요하다. 본 연구는 무기체계를 운영 및 유지보수 하는데 필요한 정비장비에 초점을 두고 있다. 최신 무기체계는 계측장비와 같은 정비장비를 활용하여 무기체계의 정렬 및 검교정 절차를 수행 후, 적정한 무기 성능이 유효하다고 볼 수 있다. 이러한 계측장비는 주기적으로 업체 외주정비(검교정 절차)를 하여 계측장비 자체의 정렬 및 상태 이상 유무를 확인해야 한다. 일반적으로 계측장비는 신뢰성이 입증된 해외업체의 계측장비를 구매하게 되고, 이러한 계측장비는 주기적으로 해외 외주정비를 받을 수밖에 없게 된다. 즉, 정비장비가 해외 외주정비를 진행하는 동안, 해당 무기체계는 성능에 대해 신뢰할 수 없으며 불가용 상태라고 볼 수 있다. 본 연구의 목적은 정비장비의 해외 외주정비로 인해 발생하는 무기체계의 손실비용과 정비장비의 구매 비용을 비교하여, 적절한 정비장비의 구매 대수를 제시하고자 한다. 본 연구의 결과가 효율적 작전 수행 보장에 기여할 것으로 판단되며, 전력 공백 문제를 해결 가능한 방안이 될 것이다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1989-1992
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• 2009

Maintenance is classified preventive maintenance before performing equipment failure and corrective maintenance after performing equipment failure. In preventive maintenance, we may analyze the failure data to end from beginning of equipment and allocate maintenance method and calculate maintenance cycle quantitatively by the failure data analysis. So, it has a merit to reduce system maintenance cost and to operate effectively but, it require high cost in system introducing and continuous operation to end of system. In corrective maintenance, we may calculate MTTR(mean time to repair) quantitatively based on function failure time. it can be based on establishing maintenance system for operation efficiency. In this paper, we may reflect the MTTR for the onboard equipped in Tilting train to establish maintenance system for Tilting train operation efficiency.