• Journal of the Korea Safety Management & Science
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• v.8 no.5
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• pp.139-150
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• 2006

The aim of this study is to establish an efficient distribution planning for a capacitated multi-stage supply chain. We assume that the demand information during planning horizon is given a deterministic form using a certain forecasting method. Under such a condition, we present a cost effective heuristic method for minimizing chain-wide supply chain inventory cost that is the sum of holding and backorder costs by using look-ahead technique. We cope with the capacity restriction constraints through look-ahead technique that considers not only the current demand information but also future demand information. To evaluate performance of the proposed heuristic method, we compared it with the extant research that utilizes echelon stock concept, under various supply chain settings.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.2
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• pp.99-112
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• 2006

In our model, we keep inventory to satisfy uncertain demands which arrives irregularly. In this situation, we have additional two constraints. First, we need to have certain amount of order consolidation (consolidation constraint) for the orders to replenish the inventory because of production or purchase amount constraint. And also, if we order at a certain date which was set by administrative convenience, we have capacity constraint to order the consolidated order demands (capacity constraint). We show this variant inventory policy is needed in steel industry and note that there will be possible similar case in industry. To deal with this case, we invent a variant replenishment policy and show this policy is superior to other possible polices in the consolidation constraint case by extensive simulation. And we derive a combined solution method for dealing with the capacity constraints in addition to the consolidation constraints. For this, we suggest a combined solution method of integer programming and simulation.

• Journal of the Korea Safety Management & Science
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• v.4 no.1
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• pp.105-114
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• 2002

Nowadays, most companies seek after the greatest profit by means of offering the goods which consumers want timely and efficiently and minimizing the cost of inventory and distribution channel which amounts to the great portion of total cost. And according as EC(Electronic Commerce) market has increased rapidly, SCM(Supply Chain Management) for EC become one of the most important facts for companies, therefore this paper suggest SCM scheme which EC, especially B to C, is added to the existing commerce system. This paper uses internet for information integration of distribution channel which is away from one another and applies TOC(Theory of Constraint)'s DBR(Drum-Buffer-Rope) Scheduling for synchronization through the whole supply chain. It is possible to synchronize the whole supply chain by means of making the speed of manufacturing and distribution to be controlled by consumer's order which is received in distribution center, and inventory and loss of sales opportunities are minimized by constant. Buffer Management. If inventories in distribution center is short, then it needs to search CCR(Capacity Constraint Resource) in supply chain and to control the speed of manufacturing and distribution according to the ability of CCR. This paper applies PT(Partial Transshipment) strategy for Delivery from distribution center to store or cyber consumer. the strategy this paper suggests chooses neighbour area from area which each distribution center takes charge, and then makes product ordered by cyber consumer which lives in the chosen area to be delivered according to inventory of distribution center.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.203-208
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• 2002

In case of the problems with multiple plants, alternative operation sequence, alternative machine, setup time, and transportation time between plants, we need a robust methodology for the integration of process planning and scheduling in supply chain. The objective of this model is to minimize the tardiness and to maximize the resource utilization. So, we propose a multi-objective model with limited-capacity constraint. To solve this model, we develope an efficient and flexible model using adaptive genetic algorithm(AGA), compared to traditional genetic algorithm(TGA)

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.10-26
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• 2005

In our model, we keep inventory to satisfy uncertain demands which arrives irregularly. In this situation, we have additional two constraints. First, we need to have certain amount of order consolidation (consolidation constraint) for the orders to replenish the inventory because of production or purchase constraint. And also, if we order at a certain date which was set by administrative convenience, we have amount constraint to order the consolidated order demands (capacity constraint). We showed this variant inventory policy is needed in steel industry and note that there will be possible similar case in industry. To deal with this case, we invented a variant replenishment policy and show this policy is superior to other possible polices in the consolidation constraint case by extensive simulation. And we derive a combined solution method for dealing with the capacity constraints in addition to the consolidation constraints. For this, we suggest a combined solution method of integer programming and simulation.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.754-757
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• 2000

인터넷을 이용한 사이버 거래가 빠른 속도로 증가함으로써 기업에게 있어 인터넷 쇼핑몰 구축은 더 이상 선택사항이 아닌 필수 사항이 되었다. 하지만 현재 사이버 거래 수준은 전통적 상거래 수준에 못 미칠뿐더러 거래 항목에 있어서도 매우 제한적인 것이 사실이다. 앞으로 사이버 거래는 계속적으로 증가하리라 전망되지만 제품의 특성 혹은 고객의 기호에 따라 전통적 상거래도 그 영역을 차지하며 함께 양립하여 발전할 것이다. 이에 본 연구에서는 기존의 상거래 시스템에 사이버 거래기능을 추가하는 모델을 제시한다. 먼저 지리적으로 멀리 떨어져 있는 유통망의 정보화를 위하여 인터넷 기술을 이용하고 공급체인(Supply Chain) 전체에 걸친 동기화를 위해 TOC(Theory of Constraint)의 DBR(Drum-Buffer-Rope) 스케줄링을 응용한다. 모든 생산 및 유통의 흐름 속도가 최종 분배 센타에 접수되는 고객의 요구에 따라 이루어지게 함으로써 공급체인 전체에 걸친 동기화를 이룰 수 있고 지속적인 버퍼 관리를 통하여서 재고의 절감은 물론 미출고의 발생도 최소화할 수 있다. 만약 분배 센타에 재고부족 현상이 일어날 경우에는 공급체인 상의 능력제약자원(Capacity Constraint Resource . CCR)을 찾아 개선 활동을 수행하며 공급체인의 흐름 속도를 능력제약자원에 맞추어 조절한다. 분배 센타에서 대리점 혹은 사이버 고객으로의 배송은 부분적 분할납품 Partial Transshipment : PT) 전략을 적용한다. 즉 각 분배 센타가 관리하는 수요지 중 인접한 지역을 부분적 분할납품 전략 적용 수요지로 선택하고 사이버 거래를 통해 생성된 물류가 부분적 분할납품 전략 적용 수요지에 분배되게 함으로써 각 분배 센타의 재고 완충역할을 수행하게 한다. 이에 따라 안전 재고 및 역 배송을 최소화 할 수 있을 뿐 아니라 미 출고로 인한 손실을 최소화하며 고객의 서비스를 일정하게 유지시킬 수 있을 것으로 기대된다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.4
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• pp.134-139
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• 2008

Most approaches for continuous review inventory problem need tables for loss function and cumulative standard normal distribution. Furthermore, it is time-consuming to calculate order quantity (Q) and reorder point (r) iteratively until required values are converged. The purpose of this paper is to develop a direct method to get the solution without any tables. We used approximation approaches for loss function and cumulative standard normal distribution. The proposed method can get the solution directly without any iterative procedure for Q, r and without any tables. The performance of the proposed approach is tested by using numerical examples. The budget constraint of this paper assumes that purchasing costs are paid at the time an order is arrived. This constraint can be easily replaced by capacity constraint or budget constraint in which' purchasing costs are paid at the time an order is placed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.126-132
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• 2012

This paper deals with a centralized warehouse problem with multi-item and capacity constraint. The objective of this paper is to decide the number and location of centralized warehouses and determineorder quantity (Q), reorder point (r) of each centralized warehouse to minimize holding, setup, penalty, and transportation costs. Each centralized warehouse uses continuous review inventory policy and its budget is limited. A SA (Simulated Annealing) approach is developed and its performance is tested by using some computational experiments.

• Proceedings of the Safety Management and Science Conference
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• 2000.11a
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• pp.163-163
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• 2000

오늘날 기업환경은 고객의 요구에 대응하여 적시에 효율적으로 상품과 서비스를 공급하고 전체비용의 대부분을 차지하는 물류와 재고비용을 줄여 기업의 이윤을 극대화하는 것으로 변화하고 있다. 예전에 기업위주의 시장형성에서 고객위주로 시장이 변화하고 있는 것이다. 이에 따라 기업은 고객의 요구에 능동적으로 대응하기 위하여 리드타임의 단축이 필수적인 요소가 되어가고 있다. 이러한 기업환경에 변화에 따른 대안으로 나온 것이 실시간 제조와 공급사슬망관리(Supply Chain Management : SCM)이다. 본 연구는 실시간 제조를 지원하기 위하여 제조업체와 협력사간의 물류에 있어 Goldratt의 Drunm-Buffer-Rope 스케줄링을 이용하여 물류창고라는 Buffer를 두어 협력사중 재고의 부족현상이 일어날 경우에는 공급체인상의 능력제약자원(Capacity Constraint Resource: CCR)을 찾아 능력제약자원이 되는 협력사에 대하여 생산을 독촉하고 물류창고에서는 부족재고에 대한 불출을 개시하여 재고의 완충을 도모하고자 한다. 제조업체와 협력사간의 정보를 실시간 감시시스템(Real-Time Monitoring System : RTMS)를 응용하여 웹상에서 공유하며, 실시간 거래가 가능토록하는 공급사슬망 구축에 관한 연구와 이를 프로그램 구현을 통해 실제적으로 시험해 보고자 한다.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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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.