• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.4
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• pp.426-434
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• 2020

This paper studies the impact of the maintenance time of anti-ship missile Harpoon on operational availability with real field data. The Harpoon maintenance simulation model is developed as a testbed for identifying the optimal inventory levels on operational availability. Using multiple linear regression analysis and integer programming, the optimal inventory levels of essential assemblies are suggested. Finally, the result of sensitivity analysis shows the quantitative impact of maintenance time on operational availability and inventory costs. The authors believe that this quantitative analysis can support policy decisions to decrease maintenance time of missiles.

• Journal of Korean Institute of Industrial Engineers
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• v.18 no.1
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• pp.11-24
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• 1992

The performance of Storage assignment policies is traditionally evaluated with the storage capacity of and AS/RS taken as given. However, the storage capacity is closely related to the inventory model used in real situations. This paper presents a model of evaluating the performance of three storage policies(random storage, class-based storage, and full turnover-based storage) considering production lot-sizing simultaneously with storage assignment of inventory items. The objective of the model is to achieve a balance of warehouse throughput and space requirements such that a total of material handling cost, production ordering cost, and inventory holding cost is minimized. The effects of the parameters involved in the model are investigated on the performance of each storage policy through example problems.

• Journal of Korean Society for Quality Management
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• v.14 no.2
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• pp.21-27
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• 1986

This paper deals with a continuous review (s,S) spare part inventory system. The distributions of service life of each part and the replenishment lead time are assumed to be exponential. Assuming that there is never more than a single order outstanding, we obtain the average annual cost of operating the inventory system. If the length of stockout period is small enough to be neglected compared to the length of operating period, the optimal operating policy variables minimizing the cost rate can be calculated iteratively. For the case of one-for-one ordering (that is, s=S-1), an exact cost rate, and a closed form decision rule minimizing the cost rate are obtained for a more general situation in which more than one order is allowed to be outstanding and the distribution of the replenishment lead time is general.

• Journal of Distribution Research
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• v.7 no.1
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• pp.1-20
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• 2002

Many of logistics-related research in automobile industry has focused on inbound logistics and procurement. Research into outbound logistics is relatively few. As a starting research into outbound logistics in automobile industry, this paper examined its logistics network problems with three aspects - location strategy, inventory strategy and transportation strategy. We proposed alternatives of logistics network design resolution, and presented three practical scenarios based on those alternatives. Based on interview, on-site visit and internal data collection processes, we identified major domestic outbound logistics problems such as redundant logistics bases, inefficient delivery policy, insufficient inventory capacity, inventory stock quality deterioration, inefficient transportation system, and etc. In order to cope with those problems, we proposed such strategic alternatives as introduction of hub-and-spoke system, integration of logistics bases, introduction of (automatic) parking building, diversification of transportation mode, and etc. At the same time, we constructed three practically executable scenarios based on those ideas. The first is "Center Hub" scenario, the second is "Metropolitan Hub" scenario. The third and last scenario is "Regional Consolidation of Warehouses (distribution centers)".

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.31-37
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• 2013

In this paper, we develop an efficient approach to solve a continuous review inventory system with a budget constraint when the semi-finished product and optional components are required to be assembled. We are, in particular, interested in a budget constraint that includes a service level. The service cost, such as labor and facility costs, tends to increase as the service level increase, and it makes the problem difficult to solve. Assuming that the reorder point for a semi-finished product is given, we show that the order quantity for the semi-finished product and the order quantity and reorder point for optional components can be determined by minimizing the total cost that includes setup cost, inventory holding cost, and shortage cost. The performance of the proposed approach is tested by numerical examples. By using sensitivity analysis, we conclude that, as the reorder point for semi-finished product increases, the order quantity for semi-finished product increases, whereas the order quantity and reorder point of optional components decreases.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.2
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• pp.263-276
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• 2004

According to the annual emission estimates of U.S.A., fugitive dust, the particulate matter entrained in the ambient air which is caused from man-made or natural activities such as movement of soil, vehicles, equipments and windblown dust, contributes 90% of PM$_{10}$ emission. In spite of an importance of fugitive dust emission in PM$_{10}$ estimation, it is excluded in the national emission inventory of Korea so far. In this paper, an emission inventory of fugitive dust for each region and in major cities throughout the country, which is the first time in Korea these values have been compiled, is presented. Sources of fugitive dust emission have been classified into paved/unpaved roads, construction operations, agricultural operations, and natural sources. The emission factors of the existing fugitive dust emission were reassessed in a way that significantly improved the reliability of the estimated result. The Korea's first national emission inventory of fugitive dust by administrative districts proposed in this paper would provide scientific reference data for establishing an reduction strategy of PM$_{10}$ and preparing effective control measures, and would contribute to academic achievement in the atmospheric environments field and the establishment of CAPSS (Clean Air Policy Support System).stem).

• Journal of Digital Convergence
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• v.15 no.4
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• pp.489-497
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• 2017

The purpose of this study is to develop case management activities inventory and analyze the perception on case management practice using importance-performance analysis(IPA) in community welfare centers. The comprehensive literature review and the content analysis from the professional scholar and social workers produced 89 items of case management activities items. A survey was conducted to 277 case managers in community welfare centers. The exploratory factor analysis, reliability and validity analysis developed the case management activities inventory comprised of 11 factors and 61 items. Suggestions were made to improve case management practice in community welfare centers.

• The Journal of Bigdata
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• v.5 no.2
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• pp.1-15
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• 2020

The duty-free industry before COVID-19 has continuously grown since 2000, along with the increase of demand in tourism industry. To cope with the increased demand, the duty free companies have kept the strategies which focused on the sales volume. Therefore, they have developed the ways to increase the volume and capacity, not the efficient operations. In the most of previous research, however, authors have proposed the better strategies for marketing and supporting policies. It is very hard to find the previous research which dealt with the operations like logistics and inventory management. Therefore, in this study, it has been predicted the future demand of frequently purchased items in airport duty free shops based on the estimated number of departing passengers by the linear regression, which concluded with the appropriate inventory level. In addition, it has been analyzed the expected effects by introducing the inventory management policy considering the cost and efficiency of operations. Based on the results of this study, it may be possible to reduce total cost and improve productivity by predicting the excessive inventory problems at duty-free shops and improving cycles of supplying items.

• Journal of Korean Institute of Industrial Engineers
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• v.36 no.1
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• pp.7-12
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• 2010

This paper considers a dynamic lot-sizing problem with backlogging under a minimum replenishment policy. For general concave production costs, we propose an O($T^5$) dynamic programming algorithm. If speculative motive is not allowed, in this case, a more efficient O($T^4$) algorithm is developed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1990.04a
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• pp.222-244
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• 1990

A multi-echelon structure of manufacturing and distribution system in considered, where the raw materials are transformed into a finished good through a number to manufacturing echelons and it is distributed to the lower echelons(retailers, or customers). The raw material, work-in-process, finished good inventory and the distribution costs are unified into one model. The objective is to determine the ordering policy of raw materials, manufacturing lot size, the number of sub-batch and the distribution policy of the finished good which minimize the annual total system cost. A computer program for a heuristic search technique is developed, by which a numerical example is examined.