• Management Science and Financial Engineering
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• v.3 no.1
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• pp.57-74
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• 1997

An EOQ-like inventory model for a manufacturing process is studied. The system is assumed to deteriorate during the production process. The results are either the production of a number of defective items, or the breakdown of the production machine. The optimal production lot size is derived. The model is extended to the case in which the probabilities of making defective items and machine breakdowns are a function of both the quantity (amount) and quality (performance) of the consumed setup cost (including the preventive maintenance cost). We further assume that the setup performance can be improved by investing in the performance improvement program. Hence, the same or a better setup outcome can be achieved with a lower setup cost. We then investigate the optimal setup cost and investment policy simultaneously, thereby achieving a better process quality and setup cost reduction concurrently.

• Quality Improvement in Health Care
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• v.27 no.2
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• pp.2-17
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• 2021

Purpose: The purpose of this study is to seek in-depth perspectives of stakeholders on the necessity and specific criteria for designating a specialized hospital for urologic diseases. Methods: Eight participants experts in urology medicine and specialized hospital system were divided into four groups. Following the semi-structured guidelines, an in-depth interview was conducted twice and a focus group discussion was conducted three times. All the interviews were transcribed verbatim and analyzed. Results: The majority of participants predicted that there would be demand for specialized hospitals for urologic diseases. The criteria of designating a specialized hospital, such as the number of hospital beds and quality of health care, have to be modified in consideration of the specificity of urology. The introduction of a specialized hospital would improve the healthcare delivery system, positively affecting hospitals and patients. Furthermore, government support is essential for the maintenance of specialized hospital systems as urology hospitals experience difficulties in generating profits. Conclusion: This study is expected to be used as base data for introducing and operating a specialized hospital for urologic diseases. In addition, it is expected that the methodology and results of this study would encourage follow-up studies on specialized hospitals and provide guidelines to evaluate the effectiveness of such hospitals in other medical fields.

• Journal of Society of Preventive Korean Medicine
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• v.15 no.2
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• pp.145-155
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• 2011

The purpose of this paper is to review the profitability of sixteen university hospitals of oriental medicine during 2007~2009. Data was collected from 16 hospitals that reveal financial statements to the public and the hospitals were classified into 7 groups. Net sales and COGS per 100 beds of the 7 groups were analyzed to measure profitability and as a percentage of net sales, the rates of personnel expenses, maintenance costs, and material costs were evaluated. The results showed that six groups had consecutively recorded net loss in medical services and differences in profitability among 7 groups were substantial. The analysis showed the profitability was significant for medium-sized hospitals. The rates of personnel expenses in net sales were above 50% in 6 groups with net loss and one group with net profit was 45%. This result indicate the rate of personnel expenses in net sales could be the main factor affecting profitability and further studies are recommended to analyze the determinants of profitability in oriental medical hospitals.

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.196-201
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• 2013

As there is no failure data for the entire lifecycle of a product, when analyzing reliability measures based on early failure data only, there may be a significant error between the estimated mean life and the real one, because it can be underestimated, or on the other hand, it can be overestimated when analyzing reliability measures based on a large amount of censored data with the failure data. To resolve the issue, this study proposes an optimal sampling estimation procedure that selects the proportion of censored data to estimate the optimal distribution with the idea that the estimated distribution could be approximated as closely as the real life distribution. This would work if we sampled the optimal proportion on the censored data, because failure data has real intrinsic distribution in any situation. We validate the proposed procedure using an actual example. If the proposed method is applied to the maintenance policy of TWC (Train to Wayside Communication) system, then we can establish the optimal maintenance policy. Thus, we expect that it will be effective for improvement of reliability and cost savings.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.525-531
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• 2006

In the port, the yard crane is very important. If a container crane or a transfer crane is broken down, it costs a lot because of the delay of work during the period of repair or reorder. But, we don't have enough spare parts because of the high cost. It is necessary to maintain high reliability of the crane through effective preventive maintenance and failure analysis. In this paper, we analyse the function and failure mechanism of the transfer crane which is a main equipment in the yard Also, we standardize failures and maintenance works using the historical data of failure and maintenance. This study which is a basic work for effective equipment operation and maintenance will support reliability engineers to decide the optimal design of the next generation equipment and operational policy of equipment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.363-366
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• 2006

In the port, Yard Crane is very important. If container crane or transfer crane broke down, it costs much money for delaying of work during the period of repair or reorder. But, we can not have enough spare parts for its high cost. It is necessary for having the reliability of crane through the effective preventive maintenance and failure analysis. In this paper, we analysed the system's function and failure mechanism of transfer crane which is main equipment in the yard. Also, we standardized the failure and maintenance work using the historical data of failure and maintenance. This study which is the basic work for IT of equipment operation and maintenance is going to be new attempt for optimal design of next generation equipment and operation policy of equipment.

• Journal of Society of Preventive Korean Medicine
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• v.14 no.1
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• pp.137-149
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• 2010

In recent decades, as the utilization of complementary and alternative medicine in the United State have been growing rapidly, regulatory controls surrounding complementary and alternative medicine(CAM) aims to ensure patient protection against unproven practices and to provide safe and effective treatments. Regulation and policy method on licensing CAM practitioners varies across the states. Over 85% of the states have the licensing system for acupuncturists, chiropractors, and naturopaths. For acupuncture, although the requirements for formal education are various across the states, a unified written examination has been adopted by almost entire states which have acupuncturist licensing law. Medicare, the public medical insurance, does not cover CAM practices except chiropractic and biofeedback. In some states, however, Medicaid programs cover some CAM therapies including acupuncture, naturopathy, and massage therapy. 67% of Health Maintenance Organizations, the private health plans, provide at least one modality of CAM services. In conclusion, government policies have been strengthened to ensure patient protection, and will continue to integrate CAM practices that are proven to be safe and effective into mainstream health care system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.11-19
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• 2009

A number of trend test methods, i.e., Military Handbook test and Laplace test etc., have been applied to investigate recurrent failures trend in repairable systems. Existing methods provide information about only existence of trend in the system. In this paper, we propose a new change-point test based on the Schwarz Information Criterion(SIC). The change-point approach is more informative than other trend test methods in that it provides the number of change-points and the location of change-points if it exists, as well as the existence of change-point for recurrent failures. The change-point test is applied to nine 300MW generating units operated in East China. We confirm that the change-point test has a potential for establishing optimal preventive maintenance policy by detecting change-point of failure rate.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.51-59
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• 2006

The purpose of this paper is to present reliability analysis procedures for repairable systems and apply the procedures for assessing the reliabilities of two subsystems of a specific group of military equipment based on field failure data. The mean cumulative function, M(t), the average repair rate, ARR(t), and analytic test methods are used to determine whether a failure process follows a renewal or non-renewal process. For subsystem A, the failure process turns out to follow a homogeneous Poisson process, and subsequently, its mean time between failures, availability, and the necessary number of spares are estimated. For subsystem B, the corresponding M(t) plot shows an increasing trend, indicating that its failure process follows a non-renewal process. Therefore, its M(t) is modeled as a power function of t, and a preventive maintenance policy is proposed based on the annual mean repair cost.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.121-129
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• 2005

In this paper, we consider a periodic preventive maintenance(PM) policy in which each PM reduces the hazard rate of amount proportional to the failure intensity, which increases since the last PM and slows down the wear-out speed to that of new one. And the proportion of reduction in hazard rate decreases with the number of PMs. Our model is similar to $ARI_1$ proposed by Doyen and Gaudoin(2004) in the sense of reduction of hazard rate. Our model has totally different wear-out pattern of hazard rate after PM's, however, and the proportion of reduction depends on the number of PM's. Assuming that 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.