• Title, Summary, Keyword: replacement policy

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Some New Results on Uncertain Age Replacement Policy

  • Zhang, Chunxiao;Guo, Congrong
    • Industrial Engineering and Management Systems
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    • v.12 no.1
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    • pp.41-45
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    • 2013
  • Age replacement policy is a commonly policy in maintenance management of spare part. It means that a spare part is always replaced at failure or fixed time after its installation, whichever occurs first. An optimal age replacement policy of spare parts concerns with finding the optimal replacement time determined by minimizing the expected cost per unit time. The age of the part was generally assumed to be a random variable in the past literatures, but in many situations, there are few or even no observed data to estimate the probability distribution of part's lifetime. In order to solve this phenomenon, a new uncertain age replacement policy has been proposed recently, in which the age of the part was assumed to be an uncertain variable. This paper discusses the optimal age replacement policies by dealing with the parts' lifetimes as different distributed uncertain variables. Several results on the optimal age replacement time are provided when the lifetimes are described by the uncertain linear, zigzag and lognormal distributions.

Preventive Replacement Policy under Increasing Minimal Repair Costs at Failure (수리비용이 증가할 때의 수리 사용 후 교환정책)

  • Park Sung-Bum;Kim Young-Min
    • Journal of the Korea Safety Management and Science
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    • v.8 no.2
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    • pp.139-153
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    • 2006
  • This paper deals with two forms of preventive replacement policy with minimal repair at failure. Those are, 1. the replacement policy I based on the cumulative operating time. 2. the replacement policy II based on the number of failures. The basic assumptions are; (1) the cost of minimal repair at failure is increasing with the number of failures since the last replacement, (2) the equipment fails stochastically with time.

Optimal Preventive Replacement Policies for a Change of Operational Environment (사용환경의 변화에 대한 최적예방교환정책)

  • Kong, M.B.
    • Journal of Korean Institute of Industrial Engineers
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    • v.21 no.4
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    • pp.507-517
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    • 1995
  • The failure rate of an item depends on operational environment. When an item has a chance failure period and a wearout failure period in sequel, the severity of operational environment causes the increase in the slop of wearout failure rate or the increase in the magnitude of chance failure rate. For such a change of operational environment, this paper concerns the change of optimal preventive replacement time. Two preventive replacement policies, age replacement policy and periodic replacement policy with minimal repair, are considered. Investigated properties are: (a) in age replacement policy, optimal preventive replacement time increases as the chance failure rate increases and optimal preventive replacement time decreases as the slope of wearout failure rate increases, and (b) in periodic replacement policy with minimal repair, optimal preventive replacement time increases as the slope of wearout failure rate increases; however, the change of chance failure rate does not alter the optimal preventive replacement time.

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A Bayesian Approach to Optimal Replacement Policy for a Repairable System with Warranty Period

  • Jung, Gi-Mun;Han, Sung-Sil
    • Communications for Statistical Applications and Methods
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    • v.9 no.1
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    • pp.21-31
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    • 2002
  • This paper considers a Bayesian approach to determine an optimal replacement policy for a repairable system with warranty period. The mathematical formula of the expected cost rate per unit time is obtained for two cases : RFRW(renewing free-replacement warranty) and RPRW(renewing pro-rata warranty). When the failure time is Weibull distribution with uncertain parameters, a Bayesian approach is established to formally express and update the uncertain parameters for determining an optimal replacement policy. Some numerical examples are presented for illustrative purpose.

Efficient Document Replacement Policy by Web Site Popularity

  • Han, Jun-Tak
    • International Journal of Contents
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    • v.3 no.1
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    • pp.14-18
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    • 2007
  • General replacement policy includes document-based LRU or LFU technique and other various replacement policies are used to replace the documents within cache effectively. But, these replacement policies function only with regard to the time and frequency of document request, not considering the popularity of each web site. In this paper, we present the document replacement policies with regard to the popularity of each web site, which are suitable for modern network environments to enhance the hit-ratio and efficiently manage the contents of cache by effectively replacing documents on intermittent requests by new ones.

A Study of File Replacement Policy in Data Grid Environments (데이터 그리드 환경에서 파일 교체 정책 연구)

  • Park, Hong-Jin
    • The KIPS Transactions:PartA
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    • v.13A no.6
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    • pp.511-516
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    • 2006
  • The data grid computing provides geographically distributed storage resources to solve computational problems with large-scale data. Unlike cache replacement policies in virtual memory or web-caching replacement, an optimal file replacement policy for data grids is the one of the important problems by the fact that file size is very large. The traditional file replacement policies such as LRU(Least Recently Used) LCB-K(Least Cost Beneficial based on K), EBR(Economic-based cache replacement), LVCT(Least Value-based on Caching Time) have the problem that they have to predict requests or need additional resources to file replacement. To solve theses problems, this paper propose SBR-k(Sized-based replacement-k) that replaces files based on file size. The results of the simulation show that the proposed policy performs better than traditional policies.

The ($\textsc{k}, t_p$) Replacement Policy for the System subject to Two Types of Failure

  • Lee, Seong-Yoon
    • Journal of the military operations research society of Korea
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    • v.25 no.2
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    • pp.144-157
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    • 1999
  • In this paper, we consider a new preventive replacement policy for the system which deteriorates while it is in operation with an increasing failure rate. The system is subject to two types of failure. A type 1 failure is repairable while a type 2 failure is not repairable. In the new policy, a system is replaced at the age of $t_p$ or at the instant the$\textsc{k}^{th}$ type 1 failure occurs, whichever comes first. However, if a type 2 failure occurs before a preventive replacement is performed, a failure replacement should be made. We assume that a type 1 failure can be rectified with a minimal repair. We also assume that a replacement takes a non-negligible amount of time while a minimal repair takes a negligible amount of time. Under a cost structure which includes a preventive replacement cost, a failure replacement cost and a minimal repair cost, we develop a model to find the optimal ($\textsc{k},t_p$) policy which minimizes the expected cost per unit time in the long run while satisfying a system availability constraint.

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Cache Replacement Policy Based on Dynamic Counter for High Performance Processor (고성능 프로세서를 위한 카운터 기반의 캐시 교체 알고리즘)

  • Jung, Do Young;Lee, Yong Surk
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.4
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    • pp.52-58
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    • 2013
  • Replacement policy is one of the key factors determining the effectiveness of a cache. The LRU replacement policy has remained the standard for caches for many years. However, the traditional LRU has ineffective performance in zero-reuse line intensive workloads, although it performs well in high temporal locality workloads. To address this problem, We propose a new replacement policy; DCR(Dynamic Counter based Replacement) policy. A temporal locality of workload dynamically changes across time and DCR policy is based on the detection of these changing. DCR policy improves cache miss rate over a traditional LRU policy, by as much as 2.7% at maximum and 0.47% at average.

An Optimal Block Replacement Policy Using Items with Different Reliability

  • Lie, Chang-Hoon;Bae, Moon-Sik;Chun, Young-Ho
    • Journal of the military operations research society of Korea
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    • v.10 no.2
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    • pp.61-73
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    • 1984
  • A block replacement policy using items with different reliability is discussed. We divide system unit failure modes into two modes and use less reliable unit when operating unit fails near the planned preventive replacement time. In this policy, item A has two failure modes. Mode-1 failure is removed by minimal repair, mode-2 failure by replacement. If mode-2 failure of item A happens in (0, $T-{\delta}$), failure item A is replaced by new item A. If mode-2 failure of item A happens in ($T-{\delta}$, T), failure item A is replaced by new item B. Item B should be cheaper and less durable than item A. Under this policy, we determine the preventive replacement interval $T^{*}$ and the interval ${\delta}^{*}$ of item B replacement which minimize the cost rate per unit time.

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A Bayesian Approach to Replacement Policy with Extended Warranty (연장된 보증이 있는 교체정책에 대한 베이지안 접근)

  • Jung, Ki Mun
    • Journal of Applied Reliability
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    • v.13 no.4
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    • pp.229-239
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    • 2013
  • This paper reports a manner to use a Bayesian approach to derive the optimal replacement policy. In order to produce a system with minimal repair warranty, a replacement model with the extended warranty is considered. Within the warranty period, the failed system is minimally repaired by the manufacturer at no cost to the end-user. The failure time is assumed to follow a Weibull distribution with unknown parameters. The expected cost rate per unit time, from the end-user's viewpoints, is induced by the Bayesian approach, and the optimal replacement policy to minimize the cost rate is proposed. Finally, a numerical example illustrating to derive the optimal replacement policy based on the Bayesian approach is described.