• 한국산학기술학회논문지
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• 제3권2호
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• pp.120-125
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• 2002

본 논문은 전자상거래의 발전으로 인해 더욱 그 중요성이 부각되고 있는 중간창고(데포)에서의 발주시스템에 관한 연구이다. 제안 모델의 특징으로는 종래의 발주점 개념에서 발주범위라는 새로운 개념을 도입한 것이다. 제안 모델에서는 종래의 발주점 방식에서 고려하지 못 했던 다품종 발주와 발주시 적재효율을 고려한 수송조건 등을 포함하여 정식화하고 모델의 해법을 제안하고 있다. 또한 수치 예를 통하여 제안 모델의 유용성을 보여주고 있다.

• 한국산학기술학회논문지
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• 제7권2호
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• pp.251-256
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• 2006

본 논문은 다단계, 다품종 조립라인을 고려한 모델이며 JIT 생산시스템에서의 최적의 발주량 계산을 목적으로 하고 있다. 제안 모델의 목적함수는 재고비와 setup 비의 합이 최소화되도록 설계되어 있다. 이는 대부분의 자동차 부품회사의 경우 setup 공정을 포함하고 있기 때문이다. 마지막으로 수치실험을 통해 제안 모델의 유효성을 보여 주고 있다.

• Industrial Engineering and Management Systems
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• 제7권3호
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• pp.257-265
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• 2008

This paper deals with the joint decisions on pricing and ordering for a monopolistic retailer who sells perishable goods with a fixed lifetime or demand period. The newsvendor-typed problem is formulated as a two-period inventory system where the first period represents the inventory of fresh or new-arrival items and the second period represents the inventory of items that are older but still usable. Demand may be for either fresh items or for somewhat older items that exhibit physical decay or deterioration. The retailer is allowed to adjust the selling price of the deteriorated items in the second period, which stimulates demand and reduces excess season-end or stale inventory. This paper develops a stochastic dynamic programming model that solves the problem of preseason decisions on ordering-pricing and a within-season decision on markdown pricing. We also develop a fixed-price model as a benchmark against the dual-price dynamic model. To illustrate the effect of the dual-price policy on expected profit, we conduct a comparative study between the two models. Extension to a generalized multi-period model is also discussed.

• 대한산업공학회지
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• 제37권4호
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• pp.358-366
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• 2011

Multi-criteria ABC inventory classification, which aims to classify inventory items by considering more than one criterion, is one of the most widely employed techniques for inventory control. The weighted linear optimization (WLO) model proposed by Ramanathan (2006) solves the problem of multi-criteria ABC inventory classification by generating a set of criterion weights for each inventory item and assigning a normalized score to the item for ABC analysis. However, the WLO model has some limitations. First, many inventory items can share the same optimal score, which can hinder a precise classification of inventory items. Second, the model allows too much flexibility in weighting multiple criteria; each item is allowed to choose its own weights so that it can maximize its score. As a result, if an item dominates the others in terms of a certain criterion, it may be classified into a higher class regardless of other criteria by assigning an overwhelming weight to the criterion. Consequently, an item with a high value in an unimportant criterion and low values in others may be inappropriately classified as class A, leading to an inaccurate classification of inventory items. To overcome these shortcomings, we extend the WLO model by using the cross-efficiency method in data envelopment analysis. We claim that the proposed model can provide a more reasonable and accurate classification of inventory items by mitigating the adverse effect of flexibility in the choice of weights and yielding a unique ordering of inventory items.

• Industrial Engineering and Management Systems
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• 제14권1호
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• pp.1-10
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• 2015

In this paper, we consider multi-item inventory management. When managing a multi-item inventory, we coordinate replenishment orders of items supplied by the same supplier. The associated problem is called the joint replenishment problem (JRP). One often-used approach to the JRP is to apply a can-order policy. Under a can-order policy, some items are re-ordered when their inventory level drops to or below their re-order level, and any other item with an inventory level at or below its can-order level can be included in this order. In the present paper, we propose a method for finding the optimal parameter of a can-order policy, the can-order level, for each item in a lost-sales model. The main objectives in our model are minimizing the number of ordering, inventory, and shortage (i.e., lost-sales) respectively, compared with the conventional JRP, in which the objective is to minimize total cost. In order to solve this multi-objective optimization problem, we apply a genetic algorithm. In a numerical experiment using actual shipment data, we simulate the proposed model and compare the results with those of other methods.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2002년도 춘계학술발표논문집
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• pp.87-89
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• 2002

본 연구는 전자상거래의 발전으로 인해 더욱 그 중요성이 부각되고 있는 중간창고(대포)에서의 반주시스템에 대한 새로운 개념을 도입한 모델을 제안하고 있다. 제안 모델은 종래의 발주점방식과 비교되는 발주범위에 의한 발주방식이며, 발주시 수송조건을 고려하고 있다. 본 논문에서는 모델의 정식화가 해법을 제안하고 있으며 수치 예를 통하여 그 유용성을 보여주고 있다.

• 한국경영과학회지
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• 제25권4호
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• pp.27-44
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• 2000

In this study we consider a spares provisioning problem for repairable items in which a parts inventory system is incorporated. If a machine fails, a replacement part must be obtained at the parts inventory system before the failed machine enters the repair center. The inventory policy adopted at the parts inventory system is the (S, Q) policy. Operating times of the machine before failure, ordering lead times and repair times are assumed to follow a two-stage Coxian distribution. For this system, we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of machines at each station and the probability that a part will wait at the parts inventory system. For the analysis of the proposed system, we model the system as a closed queueing network and analyze it using a product-form approximation method. A recursive technique as well as an iterative procedure is used to analyze the sub-network. Numerical tests show that the approximation method provides fairly good estimation of the performance measures of interest.