• Journal of the Korean Operations Research and Management Science Society
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• v.11 no.1
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• pp.44-50
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• 1986

In this paper, we find optimal policy for the (Q, r) inventory model under the lead time uncertainty. The (Q, r) inventory model is such that the fixed order quantity Q is placed whenever the level of on hand stock reaches the reorder point r. We first develop the single level inventory model as the basis for the analysis multi-level distribution systems. The functional problem is to determine when and how much to order in order to minimize the expected total cost per unit time, which includes the set up, inventory holding and inventory shortage cost. The model, then, is extended to the multi-level distribution system consisting of the factory, warehouses and retailers. In this case, we also find an optimal policy which minimizes the total cost of the contralized multi-level distribution system.

• Journal of the Korea Safety Management & Science
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• v.19 no.3
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• pp.89-95
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• 2017

This paper presents another maintenance policy for a group of units under finite operating horizon. A group of identical units are subject to random failures. Group maintenances are performed to all units together at specified intervals, and the failed units during operation are remained idle until the next group maintenance set-up. Unlike the traditional assumption of infinite operating horizon, we adopt the assumption of the finite operating horizon which reflect the rapid industrial advance and short life cycle of modern times. The units are under operation until the end of the operating horizon. Further, the operation of units are extended to the first group maintenance time after the end of the horizon. The total cost under the proposed maintenance policy is derived. The optimal group maintenance interval and the expected number of group maintenances during the horizon are found. It is shown that the proposed policy is better than the classical group maintenance policy in terms of total cost over the operating horizon. Numerical examples are presented for illustrations.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.293-309
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• 1998

This study is aimed at identifying the decision making criteria as B/C ratio, IRR and NPV based on the expected benefits and costs of the land utilization and promotion projects which have implemented to improve agricultural structure under WTO system. To carry out the objectives of the study, Sinseok project area located at Dangjin district, Chungnam province was selected. Sinseok project area has 306.2 ha of paddy area with 172 farm households. The project area will be operated by the 33 specialized farm households after completion of the project which will have 20 years of economic life. After completion of the project, farm size will be increased from 1.8ha to 9.3ha. Land intensity of the project area will be increased by 10%. Increase of land productivity and cost saving due to the labor saving technology as farm mechanization will be expected. According to the survey results, the annual amount of production cost savings per farm was estimated 3.884million won and increased total farm income was expected about 43.8million won per year. The total expexted project benefits was expected 174million won per year. The project costs to promote land utilization and structural change consisted of handling charges, and direct payment for land movility. The decision making criteria representing economic feasibility of the project such as B/C ratio, NPV and IRR were estimated 2.49, 483million won and 30% respectively when the cut-off rate was taken into account 10%. In conclusion, the land utilization and promotion project proppeled by the Korean Government under the agricultural land law is considered economically feasible from the view points of expected project benefits and costs. Accordingly the project have to be implemented more strongly under the G't financial support considering WTO and UR negociation which were aimed at achieving the free trade and improvement of international competitiveness of farm products.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.69-77
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• 1979

A single machine stochastic scheduling problem is considered. Associated with each job is its random processing time and random deferral cost. The criterion is to order the jobs so as to minimize the sum of the deferral costs. The expected sum of the deferral costs is theroretically derived under the stochastic situation for each of several scheduling decision rules which are well known for the deterministic environment. It is also shown that certain stochastic problems can be reduced to equivalent deterministic problems. Two examples are illustrated to show the expected total deferral costs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.4
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• pp.353-366
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• 2021

Objectives: An appropriate level of cost support is being proposed to maximize the participation rate. In addition, as the amount of support is highly concentrated at the level of the limit under the current level of supports, the level of cost support is low when the actual level of cost of measuring the working environment exceeds the limit. This paper describes the adjustment of an appropriate cost support rate. Methods: First, this paper analyzes the current cost support status using data from the KOSHA. Second, an alternative for adjusting the cost support rate is presented in consideration of the incentive aspect. Third, we present simulation results for the average cost support rate, the impact of each alternative on finance, and more. Fourth, the most desirable adjustment method is presented after comparing and analyzing the results of various alternatives. Results: In this paper, we present a new scale model. This model is a mixture of flat-rate, fixed rate, and subside cap. It is expected that the new model will not only facilitate participation in businesses with low measurement costs, but also have the effect of controlling measurement costs for institutions that incur greater costs. It is also expected that setting a cap will have the effect of considering government finances and inducing excessively costly institutions to reduce costs. Thus, the new model is likely to be superior to others. If the fourth plan is applied to new businesses and the fifth plan is applied to sustainable businesses, the average cost support rates will be 87.68 percent and 65.18 percent, respectively, and the needed finances will be 2.5 billion won, 18.8 billion won, and 21.3 billion won in total. Conclusions: It seems most desirable to introduce a new model that combines flat-rate, fixed-rate, and subsidy cap systems and achieve an appropriate cost support rate through this model.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.298-299
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• 2008

In this paper, supposed that can measure power quality of bus and can calculate this cost in case electric charges about customer are imposed by each bus. When reflected this in system planning, expected cost proposed following method through sample system. We calculated the nodal cost by OPF(optimal power flow) in system and the drop numbers that happen during year of loads utilizing VSCC. Also calculated BPQC using the disruption numbers. As a result, calculated bus total cost including power quality cost through case study.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.228-229
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• 2019

This study performs analyzing a status of labor cost policy of public construction project and labor management information system in Korea for improving of labor cost survey in the construction market. The outcome of this study will be helpful to build a labor cost information system included the information of man-hour, regular pay and benefit, total wage. And if these result is integrated with the information of worker's career, qualification, skill level, it is confidently expected that the survey of labor cost is reliable.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.287-295
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• 1995

This paper is concerned with cost analysis model in periodic maintenance policy. Generally periodic maintenance policy in which item is repaired periodic interval times. And in the article minimal repair is considered. Mimimal repair means that if a unit fails, unit is instantaneously restored to same hazard rate curve as before failure. In the paper periodic maintenance policy with minimal repair is as follows; Operating unit is periodically replaced in periodic maintenance time, if a failure occurs between minimal repair and periodic maintenance time, unit is replaced by a new item until tile periodic maintenance time comes. Also unit undergoes minimal repair at failures in minimal-repair-for-failure interval. Then total expected cost per unit time is calculated according to scale parameter of failure distribution. Maintenance cost factors are included operating, fixed, minimal repair, periodic maintenance and new item replacement cost. Numerical example is shown in which failure time of system has weibull distribution.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.1993-1999
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• 2011

Today, the power utilities is setting on the slow load growth and the aging of power equipment, and then could spend the efforts on the stability of system performance. Asset management may be defined as the process of maximizing corporate profit by maximizing performance and minimizing cost over the entire life cycle of power equipment. Therefore, asset management is great way to fulfill the economic investment and the stability of system performance. This paper presents the application of effective asset managem ent from an economic perspective. A proposed method is considering the life cycle analysis using life cycle cost methodology for hydro-generator during the total life cycle. The life cycle cost methodology include a way to calculating maintenance and operating costs. The proposed method will be expected to play an important role in investment decision making considering economic evaluation.

• Journal of Korean Institute of Industrial Engineers
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• v.11 no.1
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• pp.41-49
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• 1985

This paper studies the two supplier inventory system in which order-level inventory policy with constant leadtimes is adopted. An optimal ordering policy to achieve the expected minimum total inventory cost is found by utilizing the concepts of the equivalence relation. Sensitivity analysis of the system parameters, the replenishment cost and the unit price, is done through a numerical example.