• Title/Summary/Keyword: maintenance models

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Cost Models for Warranty and Preventive Maintenance

  • Kim, Che-Soong
    • Journal of Korea Society of Industrial Information Systems
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    • v.7 no.1
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    • pp.66-74
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    • 2002
  • Warranty cost analysis for one-dimensional warranties assumes that the usage intensity (or rate) is the same for all buyers. In real life the usage intensity varies across the population of buyers. Also for products sold with warranty, preventive maintenance actions by manufacturers and buyers have a significant impact on the total costs for both parties. In this paper we deals with models to study the expected warranty cost for products with free repairable warranty with varying usage intensity and three types of preventive maintenance. We also review the literature which links warranty and maintenance and develops a framework to define new topics for research in the future and examines a new model formulation. It then develops a new model and carries out its analysis.

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Maintenance of air filter system in clean room (청정실내의 공기 필터 시스템의 보전)

  • 구자항;고명훈
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.19 no.40
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    • pp.341-349
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    • 1996
  • In this paper, we deal with the problem of maintenance policies for an air filter system in clean room. Two types of maintenance policies are considered, one based on the reliability of equipment and the other one determined by the total cost including minimal repair cost. For these models, we obtain the structure of the optimal maintenance Policy which minimize the total cost. Finally we give the numerical example.

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Preventive Maintenance Policies for a System with Two Types of Units Subject to Deterioration

  • Kwon, Y.I.;Bai, D.S.
    • Journal of Korean Institute of Industrial Engineers
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    • v.8 no.2
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    • pp.33-36
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    • 1982
  • This paper considers preventive maintenance policies for a system with two types of units which is subject to deterioration. Two generalized models are investigated ; a preventive maintenance policy based on the cumulative operating time and a policy based on the number of minimal repairs performed. Optimal preventive maintenance policies which minimize the expected average cost per unit time including the earning loss due to the deterioration are discussed and some numerical examples are given.

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Development of Life Cycle Cost Model & System of the Road Tunnel (지하도로시설물의 LCC예측 모델 및 시스템 개발)

  • 조효남;선종완;김충완;민대홍
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.10a
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    • pp.157-162
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    • 2004
  • Recently, Life Cycle Cost (LCC) for civil infrastructures, such as pavements, bridges, and dams, has been emphasized. However there are few cost models for road tunnel especially for maintenance phase. The road network is composed of highways, bridges, and road tunnels. Thus it is as important as for road tunnels to keep safe for traffic. The maintenance strategies for road tunnels can be achieved based on the minimization of LCC in maintenance phase. For this purpose, in this paper, cost model and cost classification for road tunnel in maintenance phase are suggested.

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A Preventive Maintenance Model Based on the level of item degradation (마모 수준에 의거한 예방 정비 모형)

  • 구자항;김원중
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.15 no.26
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    • pp.173-179
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    • 1992
  • This paper is concerned with preventive maintenance model for the items whose failures are dependent on their wear level. The previous maintenance models have used time as their decision variable, but it is not appropriate for the case which have wear dependent processes for their failures. In this paper, we consider an operating item which is under periodic review and which is subject to degradation. The scheduled maintenance (overhaul ) is based on the level of item degradation rather time. A functional equation for the total expected cost over an infinite horizon period is formulated and solved.

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A Study on Flexible Culture in Aviation Maintenance Organization (항공정비조직의 유연성문화 연구)

  • Kim, Chun-Yong
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.23 no.1
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    • pp.1-7
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    • 2015
  • The aircraft maintenance demands a lot of aviation mechanics in urgent according to the high season and low season in seasonal demand adjusted, unplanned maintenance work such as AD (airworthiness directives) and troubleshooting of aircraft system fault. The advent of Super-Large Aircraft such as A380 with aircraft materials, power plant and avionics systems which were not in previous models must be expected to increase the complexity of the aircraft maintenance system. This study is intended to propose the development plan for formation of positive flexibility culture in aircraft maintenance organization through the review of previous research on flexibility culture of organization and through empirical research for bureaucratic and poor factors by the evaluation of flexibility culture level of domestic aircraft maintenance organization.

A Study on Optimal Preventive Maintenance Policy When Failure Rate is Exponentially Increasing After Repair (수리 후 고장률이 지수적으로 증가하는 경우에 최적 예방보전 정책)

  • Kim, Tae-Hui;Na, Myung-Hwan
    • Journal of Applied Reliability
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    • v.11 no.2
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    • pp.167-176
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    • 2011
  • This paper introduces models for preventive maintenance policies and considers periodic preventive maintenance policy with minimal repair when the failure of system occurs. It is assumed that minimal repairs do not change the failure rate of the system. The failure rate under prevention maintenance received an effect by a previously prevention maintenance and the slope of failure rate increases the model where it considered. Also the start point of failure rate under prevention maintenance considers the degradation of system and that it increases quotient, it assumed. Per unit time it bought an expectation cost from under this prevention maintenance policy. We obtain the optimal periodic time and the number for the periodic preventive maintenance by using Nakagawa's Algorithm, which minimizes the expected cost per unit time.

Digital engineering models for prefabricated bridge piers

  • Nguyen, Duy-Cuong;Park, Seong-Jun;Shim, Chang-Su
    • Smart Structures and Systems
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    • v.30 no.1
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    • pp.35-47
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    • 2022
  • Data-driven engineering is crucial for information delivery between design, fabrication, assembly, and maintenance of prefabricated structures. Design for manufacturing and assembly (DfMA) is a critical methodology for prefabricated bridge structures. In this study, a novel concept of digital engineering model that combined existing knowledge of DfMA with object-oriented parametric modeling technologies was developed. Three-dimensional (3D) geometry models and their data models for each phase of a construction project were defined for information delivery. Digital design models were used for conceptual design, including aesthetic consideration and possible variation during fabrication and assembly. The seismic performance of a bridge pier was evaluated by linking the design parameters to the calculated moment-curvature curves. Control parameters were selected to consider the tolerance control and revision of the digital models. Digitalized fabrication of the prefabricated members was realized using the digital fabrication model with G-code for a concrete printer or a robot. The fabrication error was evaluated and the design digital models were updated. The revised fabrication models were used in the preassembly simulation to guarantee constructability. For the maintenance of the bridge, the as-built information was defined for the prefabricated bridge piers. The results of this process revealed that data-driven information delivery is crucial for lifecycle management of prefabricated bridge piers.

The Evaluation of Inspection Period based on Reliability in Railway Traction Power Systems (철도급전시스템의 신뢰도기반 점검주기 산정)

  • Kim, Hyungchul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.8
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    • pp.1177-1183
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    • 2013
  • In this paper, the analysis of inspection period bases on reliability is suggested in the field of traction power system. Even though there are several maintenance models, the most commonly used maintenance assessment has been focused on time based maintenance in real traction power systems. The maintenance intervals are selected on the basis of long-time experience. It ensures high availability and exact planning of staff. Reliability centered maintenance, which evaluates criticality and severity of each failure mode, achieves the operation, maintenance, and cost-effective improvement that will manage the risks of equipment. This paper deals with electrification in railway inspection frequency and applied reliability based inspection frequency instead of constant intervals. The distribution function of failure rate in traction power system belongs to Weibull function. Also, the fault data and the number of installed equipments for electrifications are collected. The failure history is investigated and classified in detail. Though these complicated procedures, it contribute to extend equipment lifetime and to reduce maintenance costs.