• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.4
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• pp.125-138
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• 2006

This paper considers a periodic review, two-echelon inventory system with one central warehouse and several re-tailers facing normally distributed demand. The goal is to attain target fill rates, while the systemwide total holding costs are minimized. An important aspect of this problem is material rationing in the case of shortages. If a central warehouse has insufficient inventory to deliver all replenishment orders to retailers, all order quantities are should be adjusted according to some rationing rule. A simple but efficient rationing rule is proposed and compared with the Balanced Stock (BS) rationing as introduced by Heijden which is known to be the best rationing policy in the literature. Numerical results show that the proposed rationing rule is more cost effective than BS rationing, especially for the differences in holding costs between retailers are large.

• Management Science and Financial Engineering
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• v.10 no.2
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• pp.53-71
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• 2004

In this study, a mathematical model that shows the optimal payout policy is developed. The model is new and unique in the sense that not only continuous-time framework is used, but also both partial differential equation (PDE) and real-option approach are utilized in the derivation of optimal payouts for the first time. In the model building, non-linear demand curve for dividend payouts in the competitive capital markets is assumed. From the sensitivity analysis using traditional comparative static analysis, some useful managerial implications which are consistent with famous previous studies are derived under realistic conditions. All results in this study, however, are valid under the assumption that the opportunity costs follow geometric Brownian motion, which is widely used in economic science and finance literature.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.89-92
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• 1996

It is generally recognized that Video On Demand (VOD) service will become a promising interactive service in B-ISDN. We consider a hierarchical two level network architecture for VOD service. The first level consists of connected Local Video Servers(LVSs) in which a limited number of high vision programs are stored. The second level has one Central Video Server(CVS) containing all the programs served in the network. The purpose of this paper is to analyze the network traffic and to propose the storage policy for LVSs. For this purpose, we present an analysis of program storage amount in each LVS, transmission traffic volume between LVSs, and link traffic volume between CVS and LVSs, according to changing the related factors such as demand, the number of LVSs is also presented on the basis of the tradeoffs among program storage cost, link traffic cost, and transmission cost.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.137-145
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• 2012

본 연구는 공급자(supplier), 소매상(retailer) 그리고 고객(customer)으로 구성된 2 단계 공급사슬에서 소매상의 관점에서 소매상의 최적 재고정책 결정에 관한 문제를 다루었다. 공급자는 수요 증대를 목적으로 소매상의 주문량에 따라 다단계로 일정기간동안 제품 판매대금에 대한 지불 연기(외상)를 허용하고, 고객의 수요는 소매상의 제품 재고량에 영향을 받는다는 가정 하에 재고 모형을 설계하였다. 모형 분석을 통하여 소매상의 이익을 최대화하는 최적 주문량 결정 방법을 제시하였고, 예제를 통하여 그 제시된 해법의 타당성을 보였다.

• Korean Management Science Review
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• v.10 no.1
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• pp.23-39
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• 1993

In this study, potential Communication Satellite Application Services (CSASs) that are suitable for our communication environment have been identified through a detailed analysis of the CSASs offered in advanced countries. The existing demand forecast based on the defined CSAS category has been improved, and the transponder assignment policy has also been recommended. Managerial problems rather than technical ones for KOREASAT project have mainly been addressed and tackled in this study. For the successful implementation of the domestic communication satellite system, these two problems should be solved simultaneously. Therefore, future research that includes technical as well as managerial issues is expected to come out soon.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.11-21
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• 2006

Importance of and need for grid resource management have accelerated in accordance with increasing development of grid computing. However, it is very complex to distribute and utilize resources efficiently in geographically dispersed environments. This is due to the different access policies and constraints of grid resource owners. Users request resources according to their needs. Operators of a grid computing system need to be able to monitor the system states for reflecting these demands. So, a grid computing system needs a resource management policy that monitors states of resources and then allocates resources. This paper proposes a user demand-based grid trade management model that provides an efficient resource management by the trade allocation based on a users' demand and providers' supply strategy. To evaluate performance, this paper measures increasing rate of resource trades, average response time of trades, and processing time utilization. Firstly, the average increasing rates of trade are 585.7% and 322.6% higher than an auction model and a double auction model. Secondly, the average response time of the user demand-based grid trade management model is maintained between 3 and 5 simulation time. Finally, it is found that the processing time utilization is an average of 145.4% and 118.0% higher than an auction model and a double auction model. These empirical results demonstrate the usefulness of the user demand-based grid trade management model.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.278-286
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• 2014

Forestry management problems in South Korea have been caused by small and scattered forest lands, aging forest owners, and the increase of absentee forest owners. To solve these problems, it is a time to consider the introduction of forest land bank system for the expansion of forestry management scale, the effective management of neglected forest lands, and the stable livelihood support for aged forest owners. Therefore, this research implemented the questionnaire survey of necessity, expectation, willingness to use, and introduction plans for the forest land bank system in order to examine the feasibility and demand of the system focused on forest owners, non-forest owners, and people who return to the farm. The questionnaire survey was conducted for 262 of resident forest owners, 152 of absentee forest owners, 427 of non-forest owners, and 101 of people who return to the farm. 77.5% of forest owners and 63.8% of non-forest owners agreed with the necessity of the introduction for the forest land bank system. Both forest owners and non-forest owners would prefer to use forest land reverse mortgage and leasing among projects of the forest land bank. In addition, 75% of people who return to the farm also expected that forest land bank would be helpful to their rural and mountain life, and they would have higher preference to participate in leasing and buying forest lands than other projects. Based on the outputs of the feasibility and demand survey in this research, this study can play a key role in determining basic direction, major functions, types and range of projects as well as providing information for establishing policies of the forest land bank system.

• Journal of the Korea Society for Simulation
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• v.5 no.1
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• pp.13-27
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• 1996

The management of blood inventory is very important within the medical care system. The efficient management of blood supplies and demands for transfusion is of great economic and social importance to both hospitals and patients. Fro any blood type, there is a complex interaction among the optimal inventory level, daily demand level , daily supply level, transfusion to crossmatch ratio, crossmatch release period, issuing policy and the age of arriving units that determine the shortage and outdate rate. In this paper, we develop an efficient decision rule for blood inventory management in a hospital blood bank which can support efficient hospital blood inventory management using simulation, The primary use of the efficient decision rule will be to establish minimum cost function which consists of inventory levels , period in inventory, outdate and shortage rate for whole blood and various component inventories for a hospital blood bank or a transfusion service, If the adminstrator compute the mean daily demand for each blood type, the mean daily supply for each blood type, the length of the crossmatch release period and the average transfusion to crossmatch ratio , then it is possible to apply the efficient decision rule to compute the optimal inventory level, inventory period , outdate and shortage rate. This rule can also be used as a decision support system that allows the blood bank adminstrator to do sensitivity analysis related to controlled blood inventory parameters.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.683-691
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• 2018

The plastic strategy adopted by the EU in January 2018 was established to implement circular economic policies and the Sustainable Development Goals(SDGs) of the United Nations. The strategy includes the vision and implementation measures to achieve, which are primarily measures to improve recycling and increase demand for recycled plastics. The representative measures include the design that considers recycling possibilities, reinforcement of demand for recycled plastics, suppression of occurrence, and response to micro-plastics. The policies to implement these measures include legislative restrictions and economic measures (EPR, GPP). It is especially desirable that the policies are applied differently depending on the plastic product. The Korean government has established comprehensive measures for all stages from production to recycling, but those measures are not comprehensive compared to the EU's strategy. The reason is that the refusal of waste collection makes the Korean government establish the approach from the aspect of waste management instead of the implementation of a circular economy or SDGs like the EU. The countermeasures are aimed at achieving a 50% reduction in waste generation amount and a 70% recycling rate. It is considered that the possibility of achieving the goal will increase by examining the measures and policy means in the EU's plastics strategy.

• Journal of Korea Technology Innovation Society
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• v.8 no.3
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• pp.1139-1156
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• 2005

The explosive growth in wireless networks and Internet services has created considerable demand for mobile Internet services based on the mobile phone. Mobile Internet has become the new business model in telecommunication market, therefore the open network policy for mobile Internet has been formulated and implemented by the government in Korea. In spite of the open network policy for mobile Internet, there has been no systematic analysis of the various interconnection issues, including pricing, in mobile Internet network. This paper aims to suggest the interconnection pricing methods for mobile Internet network by reviewing the current pricing models for various communications services, and adapting them to mobile Internet communications circumstances. Results of this paper can be used as a guideline for government policy directions and management decision making after the introduction of the open network policy for mobile Internet.