• 산업경영시스템학회지
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• 제38권4호
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• pp.98-108
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• 2015

This paper introduces the existence of purchase dependence that was identified during the analysis of inventory operations practice at a sales agency of dealing with spare parts for ship engines and generators. Purchase dependence is an important factor in designing an inventory replenishment policy. However, it has remained mostly unaddressed. Purchase dependence is different from demand dependence. Purchase dependence deals with the purchase behavior of customers, whereas demand dependence deals with the relationship between item-demands. In order to deal with purchase dependence in inventory operations practice, this paper proposes (Q, r) models with the consideration of purchase dependence. Through a computer simulation experiment, this paper compares performance of the proposed (Q, r) models to that of a (Q, r) model ignoring purchase dependence. The simulation experiment is conducted for two cases : a case of using a lost sale cost and a case of using a service level. For a case of using a lost sale cost, this paper calculates an order quantity, Q and a reorder point, r using the iterative procedure. However, for a case of using a service level, it is not an easy task to find Q and r. The complexity stems from the interactions among inventory replenishment policies for items. Thus, this paper considers the genetic algorithm (GA) as an optimization method. The simulation results demonstrates that the proposed (Q, r) models incur less inventory operations cost (satisfies better service levels) than a (Q, r) model ignoring purchase dependence. As a result, the simulation results supports that it is important to consider purchase dependence in the inventory operations practice.

• 한국경영과학회지
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• 제17권3호
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• pp.27-46
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• 1992

This paper considers an (r, Q) policy for operation of a multipurpose facility. It is assumed that whenever the inventory level falls below r, the model starts to produce the fixed amount of Q. The facility can be utilized for extra production during idle periods, that is, when the inventory level is still greater than r right after a main production operation is terminated or an extra production operation is finished. But, whenever the facility is in operation for an extra production, the operation can not be terminated for the main production even though the inventory level falls below r. In the model, the demand for the product is assumed to arrive according to a compound Poisson process and the processing time required to produce a product is assumed to follow an arbitary distribution. Similarly, the orders for the extra production is assumed to accur in a Poisson process are the extra production processing time is assumed to follow an arbitrary distribution. It is further assumed that unsatisfied demands are backordered and the expected comulative amount of demands is less than that of production during each production period. Under a cost structure which includes a setup/ production cost, a linear holding cost, a linear backorder cost, a linear extra production lost sale cost, and a linear extra production profit, an expression for the expected cost per unit time for a given (r, Q) policy is obtained, and using a convex property of the cost function, a procedure to find the optimal (r, Q) policy is presented.

• 한국컴퓨터정보학회논문지
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• 제14권2호
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• pp.211-219
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• 2009

우리나라의 자원부족 및 치열한 가격경쟁 등으로 기업들은 물류환경은 매우 어려운 상황에 직면해 있다. 이와 같은 물류비 부담이 무한경쟁시대에 국가 경쟁력이나 기업경쟁력에서 걸림돌이 되고 있음은 자명하다. 이와 관련된 기존 연구들은 대규모 분배네트를 정의된 기호를 활용하여 하나의 통일된 수식으로 표현함으로써 분배 네트워크에 대한 시스템적 접근을 가능케 했으나, 물적 분배시스템에서 재고정책운영을 전통적 방법으로 한정하여 현실적 적용에 많은 문제점을 않고 있다. 본 연구에서는 효율적인 부재고의 처리를 위한 분배시스템의 비용분석 및 모형을 개발하여 현실적 적용을 가능케 했으며, 물적 분배시스템과 관련된 운영비용을 감소시킬 것이다.