• 산업공학
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• 제13권3호
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• pp.444-454
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• 2000

Due to the improvement of modern information technologies, sharing stock information among the supply chain members is a common practice nowadays. Many companies are planning to adopt the information systems to possess the real-time shared stock information. Thus, it is needed to quantify the value of shared stock information. The purpose of this paper is to evaluate the value of the shared stock information for two-echelon distribution systems. Existing reorder policies can be classified into installation stock policies and echelon stock policies. Since installation stock policies do not utilize the shared stock information, and both classes of policies may show poor performances for distribution systems, we cannot evaluate the value of the shared stock information with the existing policies. Thus, we provide a new type of reorder policy, named order risk policy. We define the order risk using marginal analysis, and prove the optimality. Through computational experiment that compares the order risk policy with the existing policies, it is shown that a significant cost reduction is achieved with the effective utilization of the shared stock information. We also show the effect of the system characteristics on the value of the shared stock information.

• 한국시스템다이내믹스연구
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• 제9권2호
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• pp.5-25
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• 2008

This paper analysed the impact of return policy as a coordination mechanism for decentralized supply chain with one capacitated supplier and two competing retailers under random demand distribution. In this study, Shortage gaming also considered to reflect a competing environment of two retailers. System dynamics approach was used to model the baseline two echelon supply chain and return policy on it. Given each of 4 experiment settings being used for 100 simulations with different random seeds, 400 random samples were used in a t-test. The result show that return policy significantly enhance the supply chain profits and fillrates. The analysis suggest that the supply chain performance can be build up by implementing a return policy even though under consideration of a capacitated supplier and competing retailers.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1993년도 춘계공동학술대회 발표논문 및 초록집; 계명대학교, 대구; 30 Apr.-1 May 1993
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• pp.226-226
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• 1993

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.742-749
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• 2002

This paper deals with a continuous-review two-echelon inventory model with one-for-one replenishment and Poisson demand where transshipments among retailers are allowed. Two classes of inventory systems are considered by the number of distribution centers(DCs) which provide each retailor with inventory items. 1:N class inventory system and M:N class inventory system respectively. Two-phase model is constructed to find out the optimal inventory positions which minimize supply chain costs. Approximations for customer service levels of the system are evaluated in the first phase, and the optimal inventory positions are found subject to the constraints for service level in the second phase. Simulation tests are performed to assure the effectiveness of the proposed model. The effect of transshipment is evaluated.

• 수산경영론집
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• 제30권2호
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• pp.25-37
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• 1999

Some multi echelon inventory systems carry perishable products. The value of these product reduces as the period of time they spend in the system. In this paper We derive the necessary condition to determine optimal quantity, service level for a perishable product. The systems considered consist of two echelons and carry single item. To determine the optimal order quantity, the demand is assumed to be constant, the holding costs may be different in the echelons, and it allows no shortages. I assumed the price of product decreases by negative exponential function. To determine service level, following assumptions used in the model ㆍlead time is constant. ㆍdemand is normal distribution. ㆍthe product starts to perish at the second echelon. Service level is computed for different levels of lead times and for different variance of demands and for different price functions. The experimental results indicate that the service level in cost is a function of service level in demand and perishability of product. Results of the models exhibit that perishability and the age of the product are critical to determine the lot sizing and service level.

• 산업경영시스템학회지
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• 제30권3호
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• pp.117-126
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• 2007

It has been a major issue to repair the broken system quickly for improvement of productivity and utilization. Generally, high utilization of system requires the high amount of spare parts in inventory and inventory cost. Therefore, it is necessary to determine the proper amount of inventory with regard to utilization of system. This study designs a methodology for determining the proper amount of inventory level in a two-echelon spare parts distribution system. The requirements are to satisfy proper customer demands at a distribution center and to maintain over the utilization of the whole system at customers. This methodology minimizes total inventory investment at a distribution center and customers.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1998년도 추계학술대회 및 정기총회
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• pp.46-50
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• 1998

본 연구는 최근에 국내기업의 물류비용절감을 위한 노력의 일환으로 추진되고 있는 적정 물류장비의 선정을 위한 시뮬레이션 모델의 개발이다. 본 연구에서는 제조공장에서 소비자들에게 공급되는 2단계 물류시스템에서 물류재고와 운송수단을 고려하여 최소 물류비용의 운송대안선정을 위한 의사결정을 할 수 있도록 개발하였다. 이를 위하여 2가지의 시뮬레이션모델의 전산프로그램을 개발하고 응용사례를 통하여 출력을 예시하였다.

• 산업공학
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• 제11권1호
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• pp.55-66
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• 1998

Fleet sizing and distribution of empty equipments are two of the most critical problems in managing transportation system. This paper develops a cost model for sizing a fleet and establishing decentralized redistribution polices of empty equipments by building from inventory theory of multi-echelon system in hub-and-spoke network. An analytical approach to determine control variables of redistribution policies in each terminal and fleet size of the transportation system is proposed and its results are validated by simulation model. Numerical experiments are conducted with respect to parameters of the model and test results for assumptions of the model are discussed.

• 대한산업공학회지
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• 제26권1호
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• pp.17-26
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• 2000

This paper presents an integrated order scheduling method with the improved DRP concept for multi-echelon distribution system that has the constraint of limited production capacity of producers. The proposed method reflects the dynamic characteristics of inventory level changes in the regional and central distribution center. The simulation is done with two models : the traditional DRP method and the proposed method presented in this paper. From the results, the latter is more efficient than the former in cost, customer's service level as well as balanced production load on each producer.

• Industrial Engineering and Management Systems
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• 제15권4호
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• pp.374-384
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• 2016

The efficiency of a supply chain can be extremely affected by its design which includes determining the flow pattern of material from suppliers to costumers, selecting the suppliers, and defining the opened facilities in network. In this paper, a multi-objective multi-echelon multi-product supply chain design model is proposed in which several suppliers, several manufacturers, several distribution centers as different stages of supply chain cooperate with each other to satisfy various costumers' demands. The multi-objectives of this model which considered simultaneously are 1-minimize the total cost of supply chain including production cost, transportation cost, shortage cost, and costs of opening a facility, 2-minimize the transportation time from suppliers to costumers, and 3-maximize the service level of the system by minimizing the maximum level of shortages. To configure this model a graph theoretic approach is used by considering channels among each two facilities as links and each facility as the nodes in this configuration. Based on complexity of the proposed model a multi-objective Pareto-based vibration damping optimization (VDO) algorithm is applied to solve the model and finally non-dominated sorting genetic algorithm (NSGA-II) is also applied to evaluate the performance of MOVDO. The results indicated the effectiveness of the proposed MOVDO to solve the model.