• 한국건설관리학회논문집
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• 제25권5호
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• pp.41-54
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• 2024

본 연구에서는 프리캐스트 콘크리트(Precast Concrete; PC) 제작공장의 원자재 재고관리를 위한 세 가지 재고관리 정책, 정량 발주 방식, 정기 발주 방식, (s, S) 발주 방식의 성능을 비교·분석한다. 보다 현실적인 결론의 도출을 위해, 복수 원자재를 사용하는 PC 제작공장의 전체 공정을 대상으로 원자재 수요 및 공급 측면의 변동성을 고려하여 개발된 성능평가 도구인 ARENA 시뮬레이션 모델을 활용하였다, 성능 비교를 위해, 먼저 세 가지 재고관리 정책에 대해 경제적주문량(Economic Order Quantity; EOQ)을 초깃값으로 하여 OptQuest를 통해 재주문점, 주문량, 목표수준 및 주문주기 모수를 최적화하였다. 최적화 결과, 수요 및 공급 측면의 변동성을 고려하지 않는 EOQ 방식에 비해 재고관리 비용을 평균 97.28% 감소시킬 수 있었다. 이후, 프로젝트 발생 주기, 원자재 조달기간, 단위 품절비용 등 세 가지 영향 요인을 설정한 후 세 가지 재고관리 정책에 대한 성능 비교 실험을 수행하였다. 실험 결과, 실시간 또는 매일 재고수준을 파악하여 주문 시점을 결정하는 정량 발주 방식과 (s, S) 발주 방식의 재고관리 비용이 고정 주문주기를 갖는 정기 발주 방식보다 각각 30.6%와 27.9% 낮게 나타났다. 또한, 재고관리 비용은 프로젝트 발생 주기를 제외한 원자재 조달기간과 단위 품절 비용 요인에 의해 영향을 받는 것으로 나타났지만, 그 차이는 2.17%와 2.09%로 수요 및 공급의 변동성 대응을 위한 모수 최적화 과정으로 인해 크지 않았다.

• 대한산업공학회지
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• 제20권3호
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• pp.117-124
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• 1994

In this paper an inventory model is presented for determining the ordering schedule in which the demand rate is changing linearly with time and the decay is assumed to be a constant rate of the on-hand inventory. An easy to use heuristic is developed to find the times and sizes of replenishments so as to keep the total of ordering, inventory carrying and deteriorating costs as low as possible. Solutions of the model to test problems show that our heuristic model outperforms other existing models in the literature without sacrificing the computational complexity. When there is no deterioration, the model developed is related to the corresponding model of nondeteriorating items.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2005년도 추계학술대회
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• pp.511-515
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• 2005

기업은 고객이 원하는 시기에 원하는 제품을 구매할 수 있도록 항상 준비가 되어 있어야 한다. 고객의 수요를 만족시키기 위하여 기업은 다양한 수요예측방법을 통하여 적절한 재고 수준과 수요예측을 하고 있다. 제조 기업의 경우에는 다른 산업에 비하여 정확한 수요예측과 낮은 재고 수준의 유지가 비용과 직접적인 연관이 있기 때문에 제조 기업은 경제적인 주문량 결정(Economic Order Quantity: EOQ)이 매우 중요한 문제이다. 주문량을 결정하는 방법에는 여러 가지가 있지만, 본 논문에서는 고객 지연을 방지하기 위하여 경제적 주문량 결정에 고객 지연과 관련된 비용을 포함시키는 것은 물론 고객 지연이라는 상황을 방지하는 노력의 한 방법으로 가격 할인(discount system)을 이용하고자 한다. 가격 할인을 이용하여 고객으로 하여금 빠른 주문을 유도하고 그로 인하여 고객 지연 상황의 발생을 줄여보려고 한다.

• 한국유통학회지:유통연구
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• 제2권1호
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• pp.143-174
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• 1997

The model applied in this paper is based on the theory of economic order quantity (EOQ). EOQ model is introduced to explain the improvement of the transaction efficiency through the cooperative purchase. We examine explicitly how horizontal cooperation affects vertical transactions. A result of the analysis is that a seller can prefer transacting with a cooperative rather than with each buyer separately, even if he reduces the selling price of the product. Without increasing the demand for the product, this result is that dealing with a cooperative, rather than separately with each buyer, decreases the transaction cost for the seller-buyers system, the cost reduction more than off-setting the effect of price decrease on the sellers profit. For a coopative consisting of any number of buyers, Pareto efficient ordering policies that maximize the joint cost saving for the seller-buyers system are identified. We then discuss the conditions under which a cooperative under consideration can be modified to increase efficiency gain. Next, we relax the assumption that all buyers participate in a single cooperative and examine the issue of how many cooperatives, each consisting of a subset of the buyers, should be formed to maximize the total cost saving for the seller-buyers system. Finally, the issue of shapley value to divide the cooperatives gain among its members is discussed.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2007년도 춘계학술대회
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• pp.349-357
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• 2007

We consider supply chain which consist of one manufacturer, one distributor and N retailers for a single product. This paper determines inventory replenishment period of supply chain using houristic method and propose order policy through re-coordination of inventory replenishment. Also, We develops inventory management model to calculate total cost of supply chain under assumptions of constant demand. The computational results show that the proposed inventory replenishment period and inventory management model is efficient.

• 디지털융복합연구
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• 제5권1호
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• pp.47-53
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• 2007

We consider supply chain which consist of one manufacturer, one distributor and N retailers for a single product. This paper determines inventory replenishment period of supply chain using heuristic method and propose order policy through re-coordination of inventory replenishment. Also, We develops inventory management model to calculate total cost of supply chain under assumptions of constant demand. The computational results show that the proposed inventory replenishment period and inventory management model is efficient.

• Journal of applied mathematics & informatics
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• 제6권2호
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• pp.539-552
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• 1999

An order-level inventory model for a perishable product with a time-dependent demand is developed for a fixed planning pe-riod allowing backlogging in all cycles within the said period. The market demand is assumed to decrease exponentially as time elapses. The average system cost is derived and its optimization procedure is illustrated with a numerical example. Sensitivity of the optimal so-lution to changes in the values of different parameters of the system is also analysed.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 춘계학술대회
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• pp.237-241
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• 2002

This paper deals with the problem of determining the buyer's economic lot sizing policy for exponentially deteriorating products under trade credit. It is also assumed that the ordering cost consists of a fixed set-up cost and a freight cost, where the freight cost has a quantity discount offered due to the economies of scale. We formulate the mathematical model and the solution algorithm is developed based on the properties of an optimal solution.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 춘계학술대회
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• pp.243-247
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• 2002

This paper deals with the problem of determining the buyer's economic lot sizing policy for exponentially deteriorating products under trade credit. Assuming that the supplier's credit terms are already known and the length of delay is a function of the buyer's order size, we formulate the mathematical model and the solution algorithm is developed based on the properties of an optimal solution.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.867-873
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• 2001

The purpose of this study is to find analytic solution of determining the optimal capacity (lot-size) of multiproduct acyclic multistage production and inventory system to meet the finished product demand under the constraint of finite intermediate storage. Intermediate storage is a practical way to mitigate the material flow imbalance through the line of supply and demand chain. However, the cost of constructing and operating storage facilities is becoming substantial because of increasing land value, environmental and safety concern. Therefore, reasonable decision-making about the capacity of processes and storage units is an important subject for industries. The industrial solution for this subject is to use the classical economic lot sizing method, EOQ/EPQ(Economic Order Quantity/Economic Production Quantity) model, incorporated with practical experience. But EOQ/EPQ model is not suitable for the chemical plant design with highly interlinked processes and storage units because it is developed based on single product and single stage. This study overcomes the limitation of the classical lot sizing method. The superstructure of the plant consists of the network of serially and/or parallelly interlinked non-continuous processes and storage units. The processes transform a set of feedstock materials into another set of products with constant conversion factors. A novel production and inventory analysis method, PSW(Periodic Square Wave) model, is applied to describe the detail material flows among equipments. The objective function of this study is minimizing the total cost composed of setup and inventory holding cost. The advantage of PSW model comes from the fact that the model provides a set of simple analytic solutions in spite of realistic description of the material flows between processes and storage units. the resulting simple analytic solution can greatly enhance the proper and quick investment decision for the preliminary plant design problem confronted with economic situation.