• Title/Summary/Keyword: combination warranty

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Optimal Replacement Policy for a Repairable System with Combination Warranty (혼합보증이 있는 수리 가능한 시스템에 대한 최적의 교체정책)

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    • The Korean Journal of Applied Statistics
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    • v.15 no.1
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    • pp.107-117
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    • 2002
  • In this paper we present the optimal replacement policies following the expiration of combination warranty. We consider two types of combination warranty policies: renewing warranty and non-renewing warranty. The criterion used to determine the optimal replacement period is the expected cost rate per unit time from the user'perspective. The optimal maintenance period following the expiration of combination warranty is obtained. Some numerical examples are presented for illustrative purpose.

Replacement Model Based on Cost and Downtime

  • Jung, Ki-Mun;Han, Sung-Sil;Lim, Jae-Hak
    • Journal of the Korean Data and Information Science Society
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    • v.14 no.4
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    • pp.889-901
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    • 2003
  • In this paper, we consider the optimal replacement policies following the expiration of the combination warranty. The combination warranty can be divided into the renewing combination warranty and the non-renewing combination warranty. The criterion used to determine the optimal replacement period is the overall value function based on the expected cost and the expected downtime. Thus, we obtain the expected cost rate per unit time and the expected downtime per unit time for our model. And then the overall value function suggested by Jiagn and Ji(2002) is applied to obtain the optimal replacement period. The numerical examples are presented for illustrative purpose.

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Periodic PM Policy for Repairable System with RCW or NCW

  • Jung, Gi-Mum;Kim, Dae-Kyung;Park, Dong-Ho
    • International Journal of Reliability and Applications
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    • v.3 no.3
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    • pp.113-124
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    • 2002
  • This paper suggests the optimal periodic preventive maintenance policies after the combination warranty is expired. After the combination warranty is expired, a repairable system undergoes PM periodically and is minimally repaired at each failure. And also the system is replaced by a new system at the N th PM. In this case, we derive the mathematical formula for the expected cost rate per unit time. The optimal number and period for the periodic PM that minimize the expected cost rate per unit time are obtained. Some numerical examples are presented for illustrate purpose.

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Preventive Maintenance Model after Minimal Repair Warranty (최소수리보증 이후의 예방보전모형)

  • Jung, Ki-Mun
    • Communications for Statistical Applications and Methods
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    • v.17 no.6
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    • pp.865-877
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    • 2010
  • This paper considers the periodic preventive maintenance model for a repairable system following warranty expiration. We consider three types of warranty policies: free repair warranty, pro-rata repair warranty, and combination repair warranty. Under these preventive maintenance models, we derive the expressions for the expected cycle length, the total expected cost, and the expected cost rate per unit time. In addition, we explain the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the optimal periodic preventive maintenance policy is given for a Weibull distribution case.

A Bayesian approach to replacement policy following the expiration of non-renewing combination warranty based on cost and downtime (비재생혼합보증이 종료된 이후의 비용과 비가동시간에 근거한 교체정책에 대한 베이지안 접근)

  • Jung, Ki-Mun
    • Journal of the Korean Data and Information Science Society
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    • v.21 no.5
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    • pp.873-882
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    • 2010
  • This paper considers a Bayesian approach to replacement policy following the expiration of non-renewing combination warranty. The non-renewing combination warranty is the combination of the non-renewing free replacement warranty and the non-renewing pro-rata replacement warranty. We use the criterion based on the expected cost and the expected downtime to determine the optimal replacement period. To do so, we obtain the expected cost rate per unit time and the expected downtime per unit time, respectively. When the failure times are assumed to follow a Weibull distribution with uncertain parameters, we propose the optimal replacement policy based on the Bayesian approach. The overall value function suggested by Jiang and Ji (2002) is utilized to determine the optimal replacement period. Also, the numerical examples are presented for illustrative purpose.

Maintenance Policy Based on Cost and Downtime Following the Expiration of Combination Warranty (혼합보증이 종료된 이후의 비용과 비가동시간에 근거한 보전정책)

  • Jung, Ki-Mun
    • Communications for Statistical Applications and Methods
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    • v.15 no.6
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    • pp.909-923
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    • 2008
  • This paper considers the replacement model and the preventive maintenance model following the expiration of combination warranty for a repairable system. If the system fails after the combination warranty is expired, then it is minimally repaired at each failure. The criterion used to determine the optimal replacement policy and the optimal preventive maintenance policy is the overall value function based on the expected cost rate per unit time and the expected downtime per unit time. The numerical examples are presented for illustrative purpose when the failure time follows a Weibull distribution.

The Operation Characteristics of Hybrid Supercapacitor Module for LED Emergency Luminaires (LED 비상 유도등을 위한 하이브리드 슈퍼커패시터 모듈의 동작 특성)

  • Mang, Ju-Cheul;Yoon, Jung-Rag
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.7
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    • pp.473-479
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    • 2015
  • Hybrid supercapacitors with high power density and long cycle life are widely used for emergency power source of LED emergency luminaires. In this paper, we designed and fabricated a hybrid capacitor cell and a module for the LED emergency luminaires. Using hybrid supercapacitor cells (1,000 F, 2.8 V), we designed a module in a 10-year warranty considering aging and ESR. Considering the ESR and efficiency has been designed to module with 1,000 F 5.6 V design results in 2 series and 2 parallel combination. Module was used to confirm that the operation 77.5 minutes at room temperature, discharge LED emergency luminaires with 2 W. As a LED emergency luminaires of emergency power supply that we can support more than 10 years of life was confirmed the applicability of hybrid supercapacitor.

Bilevel-programming based failure-censored ramp-stress ALTSP for the log-logistic distribution with warranty cost

  • Srivastava, P.W.;Sharma, D.
    • International Journal of Reliability and Applications
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    • v.17 no.1
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    • pp.85-105
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    • 2016
  • In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.