• The Korean Journal of Applied Statistics
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• v.26 no.1
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• pp.151-162
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• 2013

Due to a growing demand for the second-hand product, especially for the expensive one, the warranty and maintenance policies for such products have been studied to improve the product reliability of late. In this paper we study a periodic maintenance model for the second-hand product which is purchased by the customer at the age of $x$. When purchased, the dealer provides a warranty of a fixed length during which the product is maintained periodically to reduce the failure rate of the product and thus, to improve the reliability after each maintenance is served. If a failure occurs between two successive maintenances, only minimal repair is conducted. As for the warranty policy, we adopt free non-renewing repair action on each failure, in addition to the periodic maintenance service during the warranty period. Thus, under the given warranty policy, all the maintenance and repair costs incurred during the warranty period are charged to the dealer. For the proposed periodic maintenance scheme, we formulate a cost model to evaluate the expected total cost charged to the dealer during the warranty period and derive an optimal upgrade level of the failure rate at each maintenance to minimize the expected total warranty cost from the perspective of the dealer. We also present numerical results for an optimal upgrade level based on the proposed methods.

• Journal of Environmental Health Sciences
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• v.19 no.2
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• pp.88-99
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• 1993

There has been investments by firms to protect workers' health and to improve their health status. Most of the investments are made on the ground of legal requirement. However many argue that the amount of investments made falls short of the legally required level. One of the reasons why firms are not active in undertaking required investments is that they are not certain whether such investment is economically beneficial to them or not. Using CBA (Cost-Benefit Analysis), this study investigates whether firms' investments on workers' health are economically justifiable or not. All kinds of expected costs and benefits are itemized and calculated, and costs are compared with benefits. The result shows that if firms fully undertake the legally required investments, total expected costs amount to W453.2 billion and expected benefits accruing to reductions from medical care costs, workers compensation costs, litigation costs in case of legal suit, work days lost, and etc. comes up to W2,086.8 billion. In other words, economic benefits from firms' investment on industrial health far outweighs their costs. As the economy grows, the probability of having various occupational disease increases. It is well conceivable from this study outcome that, the higher the probability, the greater the social loss would be, and the greater the benefits from proper investments on workers' health.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1511-1519
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• 2013

This paper proposes the allocation method for capacitor-reactor banks in a distribution system with dispersed generators to reduce the installation costs, the maintenance costs and minimize the loss of electrical energy. The expected lifetime and maintenance period of devices with moving parts depends on the total number of operations, which affects the replacement and maintenance period for aging equipment under a limited budget. In this paper, the expected device lifetimes and the maintenance period are included in the formulation, and the optimal operation status of the devices is determined using a genetic algorithm. The optimal numbers and locations for capacitor-reactor banks are determined based on the optimal operation status. Simulation results in a 69-bus distribution system with the dispersed generator show that the proposed technique performs better than conventional methods.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.422-428
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• 2013

In many cases, an $\bar{X}$ control chart which is based on the performance variable is used in industrial fields. However, if the performance variable is too costly or impossible to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we propose a model for the economic design of a VSI (Variable Sampling Interval) $\bar{X}$ control chart using a surrogate variable that is linearly correlated with the performance variable. The total average profit model is constructed, which involves the profit per cycle time, the cost of sampling and testing, the cost of detecting and eliminating an assignable cause, and the cost associated with production during out-of-control state. The VSI $\bar{X}$ control charts using surrogate variables are expected to be superior to the Shewhart FSI (Fixed Sampling Interval) $\bar{X}$ control charts using surrogate variables with respect to the expected profit per unit cycle time from economic viewpoint.

• YAKHAK HOEJI
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• v.58 no.4
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• pp.262-267
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• 2014

Unused medication disposal is a burden due to the cost of disposing as well as the cost of the drugs. Investigating medication returns is expected to suggest areas of intervention to reduce unused medications. Purpose: The aim of this study was to examine types, quantity, costs, active pharmaceutical ingredients, and therapeutic category of the medications returned to community pharmacies. Method: From January 15, 2014 to February 28, 2014, the medications returned to the 17 community pharmacies in Gimhae, Jinju, and Incheon, Korea were examined. The pharmacists and student volunteers worked cooperatively to identify the medications and analyze drug cost of prescription pill medications returned to the pharmacies. Results: A total of 2,720 pills of prescription medication were analyzed and 91 active pharmaceutical ingredients were identified. According to the Anatomical Therapeutic Chemical (ATC) classification, the most predominant group was A (alimentary tract and metabolism) with 33.3%, followed by N (nervous system) with 15.0%. With regard to the drug cost of groups, group A was the highest with 26.6%, followed by J01 (antibacterials for systemic use) with 20.2% and N (nervous system) with 18.3%. The total cost of the oral pill prescription medications was 468,477 won. Conclusion: The result from this study implies that unused drugs impose a significant cost to the health care system in Korea. In this study, medicines used to treat gastrointestinal conditions were returned most frequently with the highest drug cost. Further research in nationwide level is necessary to establish strategies to reduce the wastage of unused medicines.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.855-866
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• 2023

With the rapid advancement and sophistication of defense weapon systems, the government, military, and the defense industry have conducted various innovative attempts to improve the efficiency of post-logistics support(PLS). The Ministry of Defense has mandated RAM-C(Reliability, Availability, and Maintainability-Cost) analysis as a requirement according to revised Total Life Cycle System Management Code of Practice in May 2022. Especially, for the project budget forecast of new PBL(Performance Based Logistics) business contacts, RAM-C is recognized as an obligatory factor. However, relevant entities have not officially provided guidelines or manuals for RAM-C analysis, and each defense contractor conducts RAM-C analysis with different standards and methods to win PBL-related business contract. Hence, this study aims to contribute to the generalization of the analysis procedure by presenting a cost analysis case based on RAM-C for the supply of military depot maintenance PBL project. This study presents formulas and procedures to determine requirements of military depot maintenance PBL project for repair parts supply. Moreover, a sensitivity analysis was conducted to find the optimal cost/utilization ratio. During the process, a correlation was found between supply delay and total cost of ownership as well as between cost variability and utilization rate. The analysis results are expected to provide an important basis for the conceptualization of the cost analysis for the supply of military depot maintenance PBL project and are capable of proposing the optimal utilization rate in relation to cost.

• Journal of Korean Society for Quality Management
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• v.24 no.4
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• pp.70-89
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• 1996

This paper discusses an optimal burn -in procedure to minimize total costs based on the assumption that some of the components are weak for stress and deteriorate faster than the main components. The procedure will define the costs of burn-in errors. An ideal burn-in consists of process in which all weak (substandard) components and no main (standard) components fail. In practice, the burn-in errors could occur for some reasons. For example, it is impossible to eliminate all weak components through burn-in, due to a nonzero proportion of defectives of the components. Probability model and cost function model are formulated to find the optimal burn-in time that minimizes the expected total cost. Several examples are included to show how to use the results.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.149-157
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• 2013

PURPOSES : This study is to analysis for benefit and construction cost in underpass for small vehicles. METHODS : The study was performed using the traffic software VISSIM 5.20 for analysis on a variety of traffic conditions and analysed of benefits of changes through analysis of travel speed and travel time after modeling of existing underpass and small vehicle underpass. RESULTS : Results of this study, the benefits will be reduced by the introduction underpass for small vehicles were analyzed because heavy vehicles use the intersection above the underpass. However, it was required economic analysis considering both the benefits reduction and the construction costs reduction because it has the effect of reducing the construction cost. Showed that the difference in benefit changes depending on the v/c and heavy vehicles ratio and construction cost was difference by types of underpass. As a result of performing economic analysis with total benefits and construction cost, it was analyzed to be economical in underpass over a certain size. CONCLUSIONS : The result of this study are expected to be able to contribute to reviewing for feasibility due to the small vehicles underpass introduction and economic analysis. The study is case study to the underpass in Daegu. Therefore, the future requires the calculation of benefits reflect a wider range of traffic conditions and the economic analysis to construction cost calculation for various types of grad separation facilities.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.510-515
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• 2011

Urban renewal projects, in the form of mega-projects, are being actively implemented both nationally and internationally to revitalize inactive cities. These programs, however, are difficult to manage efficiently due to their need for a large budget over a long period of time and due to conflicts with stockholders. Moreover, existing cost and duration management systems are structured with emphasis on the design and construction stage of unit projects, thus limiting their application to long-term mega-projects that are integrated with various facilities. To solve these problems, this study developed a web-based system that can collectively manage the cost and duration of mega-projects at a program level. The unit modules included in the system--CBS organization, construction cost and duration prediction, and total cost and duration prediction--can support decision-making at the early stage of the program. Furthermore, the modules, which include contract management, execution management, change management, and program progress management, support the program operations for its successful accomplishment. The web-based cost and duration management system developed in this study is expected to be used as a valuable tool that supports the successful accomplishment of mega-projects through their efficient management throughout their life cycle.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.81-88
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• 2011

Providers haven't recently had a flexible construction cost estimation system to meet various needs of consumers about public housing. So the subject of this study is to estimate construction cost reasonably in early project stage of public housing and then develop reliable means which is able to support construction cost management and establish a adequate funding investment plan as a provider. In this study, Regression analysis was performed by the case on 20 public apartment complex which were designed from the first half of 2007 to the first half of 2008. A total construction cost of construction, civil engineering, machinery, elevator, land scape, electricity and communication work was used as one sample for increasing explanation and representativeness of the case. In addition, The total construction cost which is devided into design, contract and completion cost was variously analysed for increasing relevance of model and actual utilization. The result of estimation model based on a total construction cost set up completion and design cost showed that error rate is within 2%, which is a excellent result. The estimation model of the construction cost developed by this study is expected to estimate approximate construction cost which is adjacent real construction cost in early stage of the project by using some data.