• Communications for Statistical Applications and Methods
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• v.6 no.1
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• pp.99-106
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• 1999

This paper considers an imperfect repair model for which the repairable system is maintained preventively at periodic times and is replaced by a new system when a predetermined number of preventive maintenance has been applied. our main objective of this is to determine the optimal number of preventive maintenances before the system is replaced and the optimal length of interval between two consecutive preventive maintenances under a new repair model which is referred to as an ineffective preventive maintenance. Such a model assumes a periodic preventive maintenance in which the system is effectively maintained with a certain probability. Otherwise the system is not improved at all after each maintenance and thus the failure rate remains the same as before. The criteria to determine the optimal number of preventive maintenances and length of period is the expected cost rate per unit time for an infinite time span. We give the explicit expressions for the expected cost rate per unit time. Some numerical examples are presented for illustrative purposes.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.773-781
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• 2013

Recently, an extended warranty of the system following the expiration of the basic warranty is becoming increasingly popular to the user. In this respect, we suggest a preventive maintenance model following the expiration of extended warranty with minimal repair warranty from the user's point of view in this paper. Under basic warranty and extended warranty, the failed system is minimally repaired by the manufacturer at no cost to the user. For the preventive maintenance model, we derive the expressions for the expected cycle length, the expected total cost and the expected cost rate per unit time. Also, we determine the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the numerical examples are presented to illustrate the purpose when the failure time of the system has a Weibull distribution.

• Journal of the Korean Data and Information Science Society
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• v.22 no.4
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• pp.775-784
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• 2011

In this paper, we consider the periodic preventive maintenance model for repairable system following the expiration of non-renewing free replacement-repair warranty (NFRRW). Under this preventive maintenance model, we derive the expressions for the expected cycle length, the expected total cost and the expected cost rate per unit time. Also, we determine 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 Weibull distribution case.

• 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 Preventive Medicine and Public Health
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• v.46 no.6
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• pp.293-299
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• 2013

Objectives: The purposes of this study were to evaluate the prevalence of epilepsy and to estimate the cost of epilepsy in Korea, 2010. Methods: This study used a prevalence based approach to calculate the cost of epilepsy. Claims data from the Korean national health insurance and data from the Korea health panel, the Korea National Statistical Office's records of causes of death, and labor statistics were used to estimate the cost of epilepsy. Patients were defined as those who were hospitalized or visited an outpatient clinic during 2010 with a diagnosis of epilepsy (International Classification of Diseases 10th revision codes G40-G41). Total costs of epilepsy included direct medical costs, direct non-medical cost and indirect costs. Results: The annual prevalence of treated epilepsy was 228 per 100 000 population, and higher in men. The age-specific prevalence was highest for teenagers. The total economic burden of epilepsy was 536 billion Korean won (KW). Indirect cost (304 billion KW) was 1.3 times greater than direct cost (232 billion KW). By gender, the male (347 billion KW) were more burdened than the female (189 billion KW). The estimated cost in young age younger than 20 years old was 24.5% of the total burden of epilepsy. Conclusions: A significant portion of the economic burden of epilepsy is borne by people in young age. To reduce the economic burden of epilepsy, effective prevention and treatment strategies are needed.

• Journal of Preventive Medicine and Public Health
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• v.45 no.5
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• pp.291-300
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• 2012

Objectives: We aimed to estimate the annual socioeconomic burden of coronary heart disease (CHD) in Korea in 2005, using the National Health Insurance (NHI) claims data. Methods: A prevalence-based, top-down, cost-of-treatment method was used to assess the direct and indirect costs of CHD (International Classification of Diseases, 10th revision codes of I20-I25), angina pectoris (I20), and myocardial infarction (MI, I21-I23) from a societal perspective. Results: Estimated national spending on CHD in 2005 was $2.52 billion. The majority of the spending was attributable to medical costs (53.3%), followed by productivity loss due to morbidity and premature death (33.6%), transportation (8.1%), and informal caregiver costs (4.9%). While medical cost was the predominant cost attribute in treating angina (74.3% of the total cost), premature death was the largest cost attribute for patients with MI (66.9%). Annual per-capita cost of treating MI, excluding premature death cost, was $3183, which is about 2 times higher than the cost for angina ($1556). Conclusions: The total insurance-covered medical cost ($1.13 billion) of CHD accounted for approximately 6.02% of the total annual NHI expenditure. These findings suggest that the current burden of CHD on society is tremendous and that more effective prevention strategies are required in Korea.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.65-76
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• 1990

Hospitals are experiencing an increasing amount of financial difficulty due to government control of hospital rates since national health insurance has been implemented. The decision support system (DSS) was developed to provide cost and revenue information for the services rendered by each department in an effort to reduce costs. This information may be used to identify the causes of financial loss if cost exceeds revenue and to conduct variance analysis or portfolio analysis to improve financial situation of hospitals. The DSS was developed using a micro-mainframe interface approach where the mainframe computer collects and summarizes daily cost and revenue data and the micro computer computes the cost for each department. The significances of this paper are to determine the cost allocation basis and methods which are suitable to Korean situation and to apply DSS technology to the cost analysis.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.4
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• pp.390-399
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• 2011

Generally the life-cycle cost of complex systems composed of several sub systems or equipments such as train, aircraft weapon systems is spent much more during operation and maintenance phase than development phase. The maintenance cost for maintaining the availability and extending the life span of systems comprise a large proportion of systems operation cost. The cycle of preventive maintenance affects operation and maintenance cost a lot. In this study we introduce a way minimizing life-cycle cost of systems by calculating more reliable preventive maintenance period than the results of previous study using systems reliability data considered the reliability and failure effect ratio of sub-systems or components. We can solve the preventive maintenance period problem known as NP-Hard as quick as possible by using modified genetic algorithm than using other models introduced in previous study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.331-336
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• 2018

In this paper, the life cycle cost of the auxiliary power unit in the conventional 8200 series electric locomotive is evaluated and an effective life cycle cost reduction method is sought. For this, a life cycle cost evaluation model was proposed using IEC 60300-3-3 standard. As a result of analysis, material cost which accounted for a large percentage of preventive maintenance cost, accounted for 64% of total cost, and breakdown maintenance cost was as high as 27%. Except for the cost of preventive maintenance, the breakdown maintenance cost ratio was the highest. In order to reduce the LCC of the auxiliary power unit(APU) of the 8200 series in the future, it is necessary to reduce the material cost in case of development and to secure the high reliability according to the parts manufacturing so as to minimize the maintenance cost.

• Journal of Korean Society for Quality Management
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• v.31 no.3
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• pp.193-204
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• 2003

In this paper, we consider a periodic preventive maintenance(PM) policy in which each PM reduces the hazard rate but remains the pattern of hazard rate unchanged. And the system undergoes only minimal repairs at failures between PM's. The expected cost rate per unit time is obtained. The optimal number N of PM and the optimal period x, which minimize the expected cost rate per unit time are discussed. Explicit solutions for the optimal periodic PM are given for the Weibull distribution case.