• 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.

• Proceedings of the Korean Statistical Society Conference
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• 2001.11a
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• pp.125-130
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• 2001

본 논문에서는 혼합보증기간이 있는 수리 가능한 시스템에 대한 최적의 교체정책을 제안한다. 이 교체정책은 보증기간이 재생되는 경우와 재생되지 않는 두 가지 경우에 대해서 고려되며, 최적의 교체주기를 결정하기 위해서 사용자 관점에서의 단위 시간당 기대비용을 사용한다. 시스템의 고장시간이 와이블 분포를 할 때 수치적 예를 통해서 제안된 최적의 교체정책을 설명한다.

• 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.

• 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.

• 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.

• The Magazine for Energy Service Companies
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• s.77
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• pp.18-21
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• 2012

정부는 지난 '10년 "ESCO산업 활성화 방안"을 발표, ESCO산업 진흥을 통해 국가 에너지 및 온실가스 절감목표를 달성하고 고용창출과 수출을 제고하는 신성장동력을 육성하겠다고 밝혔다. ESCO산업 활성화 방안은 ESCO성과보증계약을 확산하여 ESCO의 기술력을 향상시키고 수익성을 개선시키는 내용을 담고 있다. 성과보증제도 확산의 일환으로 성과배분계약 및 성과보증계약의 장점을 혼합하여 신성과배분계약방식을 '11년부터 도입하였으며, '13년에는 성과배분계약에 대한 정책자금 지원을 중단할 예정이다. 이러한 성과보증 육성정책으로 '10년 ESCO 사업 중 10%에 불과하던 성과보증계약 비율이 지난해 58%로 껑충 뛰는 등 놀라운 성과를 거두었다. 이러한 변화의 추세에 발맞추어, 협회에서는 ESCO실무자에게 직접 성과보증방식 위주의 ESCO사업 추진에 대해 실질적인 이야기를 들어보고 성과배분계약 지원 중단 정책에 대비하여 얼마나 준비가 되어있는지 점검해보았다.

• Korea Trade Review
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• v.41 no.2
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• pp.231-250
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• 2016

The study attempts to consider L/G(Letter of Guarantee) in a different angle, which is internationally used as a way of commercial customs and practices in a case when the consignee wants to receive the goods without the original Bill of Lading, Thus, this study focuses more on verifying the usage of L/G in Mixed Payment System and the range of guarantee responsibility by an issuing bank through case analysis. This case uses a mixed payment method of L/C(Letter of Credit) and T/T(Telegraphic Transfer) in the transaction of goods. The issuing bank of L/C issues L/G with the amount of L/C which is the same as the amount as C/I(Commercial Invoice). However the carrier deliver all goods laden under both L/C and T/T payment with the production of L/G. In this case, because the buyer is unable to pay, the seller makes a claim for damages to the carrier that the carrier delivers the goods to the buyer against L/G. Finally, the judge gives a decision that the issuing bank of L/G should pay the whole amount of the goods. In this case, the main issue of the dispute is the range of guarantee responsibility by the issuing bank of L/G. As a result of the case analysis, the study suggests two counter strategies for smooth utilization in international trade environment. First, in the case of mixed payment system, a seller should issue a commercial invoice separately based on the amount of each settlement plan in order to clarify the liability of guarantee. Second, banks should establish a new form for L/G including a sentence for verifying liabilities of the bank's side in the current form of L/G.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.12 no.20
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• pp.39-45
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• 1989

This article is concerned with cost analysis in product warranty policy. The warranty cost can be different according to warranty rate and warranty renewal policy. In this paper the stepdown warranty is used. The warranty renewal policy is considered when the warranty is received upon free replacement period as item failing. Assuming the non repairable item as one item is sold, investigated manufacturer's cost in stepdown warranty policy. Also manufacturer's cost is calculated in the free replacement. pro-rata. hybrid policy. Numerical example is given over Weibull time to failure distribution, comparing stepdown warranty policy with free replacement, pro-rata, hybrid one in the manufacturer's point of view. The sensitivity analysis of warranty cost according to the number of warranty period step is included.

• The Korean Journal of Applied Statistics
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• v.8 no.1
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• pp.89-104
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• 1995

This paper is concerned with the method of estimating lifetime distributin from field data for products with multiple modes of failure. When product failures occur within warranty period, a manufacturer can obtain failure-record data; failure times, causes of failure, and covariates. Since these data are seriously incomplete for satisfactory inference, that is, only failures occured during warrantly period may be recorded, it is usually necessary to incoporate the failure-record data by taking a supplementary sample of items obtained following up a portion of products that survive warranty time. The log linear function is considered as a model for describing the relation between failure time of a product and covariates. General methods for obtaining pseudo maximum likelihood estimators(PMLEs) for the parameters are outlined and their asymptotic properties are studied, and specific formulas for exponential or Weibull distribution are obtained. Effects of follow-up percentage on the PMLEs are investigated. Extensions to calendar time warranty or calendar and obtaining time warranty are also considered.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.555-560
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• 1996

막대한 연구재원이 소요되는 원자력 개발분야에서 세계 초일류수준을 유지하고 있는 선진 원자력 연구개발사업기관들은 하나같이 종래에 도입한 "원자력 품질보증체제"를 확대시켜 "품질 무한경쟁시대"에 부응하는 "종합적 품질경영체제"를 도입하고 있다. 본 연구에서는 효율적인 연구소 경쟁력제고 방안도출을 위한 노력의 일환으로 현재 Total Quality Management(TQM) 체제를 도입하고 있는 해외의 ORNL(Oak Ridge National Laboratory), AECL(Atomic Energy of Canada Limited), ABB CE(Asea Brown Boveri Combustion Engineering), DNA(Defense Nuclear Agency)등을 방문한 결과를 토대로 연구소적 TQM체제 성공과 실패의 원인을 분석하여 도입당시의 추진조직, 추진전략, 추진효과에 대해 체계적으로 비교 분석하여 한국정서에 부합된 연구소적 성공 TQM체제 모델을 도출코져 시도하였다. 분석결과 이들 기관들은 TQM 추진을 위하여 먼저 단계별로 단기, 중기, 장기 계획을 수립하고, TQM 실무위원회를 구성하여, 최고경영자가 직접지휘하는 Top-down 방식의 TQM 추진으로 품질문제를 사전에 예방하고 있었다. TQM 도입 초기 실무부서로 부터의 적잖은 저항과 애로사항이 도출되어 많은 시행착오를 거쳤으며 지금은 TQM 정착단계에 있었다. 이러한 과정에서 원자력 선진기관들은 전사적인 TQM 교육을 통해 철저한 TQM 마인드를 고취시켰고 전 부서의 업무가 전사적 TQM 차원에서 수행되었다. 우리나라 원자력기관에서의 바람직한 TQM 도입 모델로서 첫째, 전직원 대상 TQM 교육실시를 통한 TQM 인식고취, 둘째, TQM 성공체제로서 "경영품질"에 초점을 맞춘 관리시스템 확보, 셋째, 동서문화 차이를 고려한 Bottom-up '||'&'||' Top-down 혼합방식을 제시하였다.ottom-up & Top-down 혼합방식을 제시하였다.