• The Journal of the Korea Contents Association
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• v.6 no.2
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• pp.9-16
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• 2006

This paper proposes a scheduling algorithm for efficiently processing multimedia pakcet services in OFDMA physical system of the future broadband wireless access networks. The scheduling algorithm uses wireless channel state estimation, and allocates transmission rates after deciding transmission ordering based on class and priority policy. As the result, the proposed scheduling algorithm offers maximum throughput and minimum jitter for realtime services, and fairness for non-realtime services. In simulation study, the proposed algorithm proves superior performances than traditional round robin method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.2
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• pp.145-151
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• 2015

As order quantity is increased, the ordering cost per item will be cheaper due to saving of transportation and material handling costs. In this paper, two realistic assumptions such as quantity discount and budget limit are considered. Quantity discount means that all units in the order will be discounted according to the predetermined order levels. Budget limit represents that the costs for inventory investments are bounded. This paper develops a Lagrangian relaxation approach for a continuous review inventory model with a budget constraint and quantity discounts. Computational results indicate that the proposed approach provides a good solution. Sensitivity analysis is done to get some insights on budget limit and quantity discount. As budget limit or the amount of discount according to order quantity is increased, order quantity is increased, whereas reorder point is not always increased.

• 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 Korean Society of Industrial and Systems Engineering
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• v.24 no.65
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• pp.23-30
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• 2001

In this paper, we consider an inventory system in case the toleration to be inventory stortage under the price discount. It has been observed that suppliers suggest a free addition of marketing policy like a price discount. A major reason for a supplier to offering a free addition to a customers is to stimulate the demand and to decrease a total cost. but, If we not adapting to the toleration to be inventory-lacking, we will a burden holding costs in a relation to the holding of inventory. This paper, is a combination of the toleration of inventory shortage and the condition of discount price. The costs are defined as the sum of the ordering, holding, shortage, purchasing and opportunity costs. Based on numerical results, conclusions follow about the total of operation costs the division of the shortage rate of inventory.

• Journal of the Korea Safety Management & Science
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• v.18 no.4
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• pp.185-193
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• 2016

Now, many studies of industrial field are focusing on the whole optimization of SCM. But, the reason for making simultaneity of the whole system of SCM difficult is reduced scale of studies on ordering area in SCM reducing the complexity. It's an important issue how to allocate orders in the environment of many suppliers under special situation. Through this thesis, this research intends to expect systematic and arranged supply of distribution area which can make a decision while allocating product orders and quantity and maintaining service standard suggested by minimizing total purchase costs.

• Journal of Digital Convergence
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• v.13 no.11
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• pp.7-14
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• 2015

The purpose of this study is to present the base for activation policy for cost estimation guidelines of e-Learning content development. To achieve this purpose, this study investigates the effectiveness of cost estimation guidelines of e-Learning content development through a survey about executives and employees in the e-Learning industry and analyses them statistically. According to an analysis, companies(which abandoned order because the amount of money (cost) of e-Learning contents ordering is low and suffered a loss after acquiring e-Learning contents project order) have a relatively negative awareness about the effectiveness of cost estimation guidelines of e-Learning contents. On the other hand, contents focused companies have a relatively positive awareness about the effectiveness of cost estimation guidelines of e-Learning contents. In conclusion, this study suggests that government should recommend and enact announce the use of cost estimation criteria(guidelines) of e-Learning content development and provide the institutional tools soon as possible.

• Journal of Digital Convergence
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• v.13 no.3
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• pp.11-18
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• 2015

After entering a convergence era, South Korea Government has enacted and announced the Standard Contract on the e-Learning Content Development Project, a year and eight months has passed. Nevertheless, there has been continued still the unjust and unreasonable contract practices issues raised by project owner in the e-Learning industry. This study investigated application status of the Standard Contract via FGI and questionnaires and suggested its improvement alternative. This study analyzed that the Standard Contract has not taken root at all in ordering of the e-Learning content development project and not reaped the effect. This study presented alternatives such as mandatory application of the Standard Contract, education and outreach, introduction of the monitoring system, certification system implementation, granting of additional points in the evaluation of agencies and CEO and etc. to that standard contract is settled as the government's intentions and objectives in the e-Learning industry field.

• Journal of Digital Convergence
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• v.12 no.2
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• pp.327-333
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• 2014

Recently, most of computing technology is based on web. Therefore, the users register web services or needed resources, and they can find and use the registered item. These services can be used alone or can be used in combination. When the item is used in combination, the ordering and association of service is important, and an ontology that defined association of services is required. In this paper, we define association of services based on ontology, and propose a method that can be used by services integration. The proposed method provides an efficient retrieval service by compositing the ontology with the service area and data association area.

• Management Science and Financial Engineering
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• v.15 no.1
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• pp.1-31
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• 2009

This paper considers the value of warehousing contract under probabilistic demands. We consider a supply chain consisting of a supplier, a retailer and its third-party warehousing partner who provides the warehousing service to the retailer through an outsourcing contract. A typical contract is specified by initial space commitment and modification schedule. The retailer decides the order quantity for the supplier and space commitment for the outsourcing contract. Since there is close relationship between order quantity and space commitment to minimize the total cost including ordering cost, inventory carrying cost, shortage cost, and warehousing cost, we develop an analytical model under probabilistic demands, where the retailer can determine the optimal order size and space commitment level jointly. We found the closed-form optimum for a single-period case and the optimal conditions for a two-period case. To evaluate the value of contract flexibility for the two-period case, we compared the total cost under two policies; one with modification, under which the base commitment can be changed at the start of each period and the other without modification. From results of our numerical analysis, we showed that the modification policy is more cost-effective as the variability of demand increases.