• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.3
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• pp.27-40
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• 2006

Today's customer demands in supply chains tend to change quickly, variously even in a short time Interval. The uncertainties of customer demands make it difficult for supply chains to achieve efficient inventory replenishment, resulting in loosing sales opportunity or keeping excessive chain wide inventories. Un this paper, we propose an adaptive vendor managed inventory (VMI) model for a two-echelon supply chain with non-stationary customer demands using the action-reward learning method. The Purpose of this model is to decrease the inventory cost adaptively. The control Parameter, a compensation factor, is designed to adaptively change as customer demand pattern changes. A simulation-based experiment was performed to compare the performance of the adaptive VMI model.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.2
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• pp.45-56
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• 2012

This paper considers a supply chain consisting of a component manufacturer and a product manufacturer. The component manufacturer provides components for the product manufacturer based on a vendor-managed inventory type of supply contract, and also faces demands from the market with the option of to accept or reject each incoming demand. Using the Markov decision process model, we examine the structure of the optimal production control and inventory rationing policy. Two types of heuristics are presented. One is the fixed-buffer policy and the other uses two linear functions. We implement a computational study and present managerial insights based on the observations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.141-150
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• 2014

Due to their accessibility and 24-hr availability, convenience stores are an integral part of daily lives. Because they sell a limited number of products and have small shelf space, shelf space allocation and inventory replenishment are important considerations for inventory management that critically affect profit. In this paper, we propose five solutions for the vendor-managed inventory problem of convenience stores that maximize profit while considering stock-out-based product substitutions. The performance of the proposed solutions is evaluated via simulation to reflect the demand uncertainty and marketing activity.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1194-1197
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• 2006

최근 소매점 공급사슬을 전체적인 관점에서 효율적으로 운영하기 위하여 공급자가 소매점의 재고를 관리하는 공급자 주도 재고관리(Vendor Managed Inventory; VMI)정책의 도입이 확산되고 있다. VMI 정책은 소매점에서 직접 수행하는 재고관리(Retailer Management Inventory; RMI)와는 달리 소매점의 재고수준에 대한 의사결정과 재고유지에 대한 재정적인 책임이 소매점으로부터 공급자에게 옮겨진다. 이에 따라 소매점은 공급자로부터 수시로 재고를 보충 받게 되고 주문절차는 사라진다. 또한 재고공간의 크기를 줄일 수 있게 된다. 공급자 또한 전체 소매점에 대한 효율적인 분배로써 비용절감의 효과를 기대할 수 있게 된다. 본 연구에서는 품절을 고려하며 소매점의 판매수요가 확정적인 상황에 대하여 RMI와 VMI에 대한 총비용을 최소화하는 수리모델을 통해 총비용 관점에서 RMI와 VMI정책을 비교하고자 한다. 계산실험을 통해 RMI와 VMI의 총비용 변화에 민감한 요인들을 분석하였고 VMI 적용으로 총비용을 절감시키기 위한 조건을 모색하였다. 실험결과, VMI의 적용은 항상 총비용 절감 효과를 나타내는 것이 아님을 확인 하였고 RMI에 대한 VMI의 총비용 증감효과는 RMI 정책의 소매점 주문비와 VMI정책의 소매점 재고공간의 크기 변화에 가장 크게 영향을 받는 것으로 나타났다. 이를 토대로 간단한 소매점 공급사슬에 대해서 VMI의 총비용 감소조건을 제시하였다.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.3
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• pp.362-372
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• 2008

Manufacturers, or vendors, and their customers continue to adopt vendor-managed inventory(VMI) program to improve supply chain performance through collaboration achieved by consolidating replenishment responsibility upstream with vendors. In this paper, we construct a mixed integer linear programming model and propose a genetic algorithm for the integrated inventory and routing problems with lost sales maximizing the total profit in the VMI supply chains which comprise of a single manufacturer and multi-retailer. The proposed GA is compared with the mathematical model on the various sized test problems with respect to the solution quality and computation time. As a result, the GA demonstrates the capability of reaching solutions that are very close to those obtained by the mathematical model for small problems and stay within 3.2% from those obtained by the mathematical model for larger problems, with a much shorter computation time. Finally, we investigate the effects of the cost and operation variables on the total profit of the problem as well as the GA performance through the sensitivity analyses.

• Proceedings of the Safety Management and Science Conference
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• 2005.11a
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• pp.129-134
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• 2005

VMI(Vendor Managed Inventory)가 사회적인 관심사로 부각되고, 전 부분으로 확산 되고 있음에도 불구하고 VMI의 도입적용에 관한 연구 및 문헌자료는 찾아보기 힘들 정도로 부족한 실정이다. VMI에 관한 연구의 대부분이 재고기법에 관한 응용연구에 편중되고, 공급체인상의 하부기능으로 일부 언급되었을 뿐, 공급체인상의 프로세스를 중심으로 VMI의 실증연구가 이루어진 자료는 전무한 실정이다. 이러한 상황에서 VMI의 도입 구축 프로젝트추진을 계기로 VMI의 적용에 따른 물류 프로세스 개선에 관한 연구를 하였다.

• Journal of Distribution Science
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• v.14 no.4
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• pp.21-31
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• 2016

Purpose - This study examines how consignment and Vendor-Managed Inventory perform as supply chain collaboration programs. By using three key collaborative features, this study defines the collaboration programs and develops theoretical models of different supply chain systems. Research design, data and methodology - This study conducts sophisticated analysis on the supply chain systems by applying simulation modeling based on time-phased operations. The simulation model represents a two-stage supply chain system where a supplier sells a single item to a buyer, and it incorporates various operations. Results - In general, the simulation outcomes support that more advanced collaboration programs outperform less advanced ones. The analysis on the simulation outcomes identifies the significant value of information sharing in both collaboration programs. The specific conditions where the particular collaboration system outperforms the others are recognized. Conclusions - The outcome of this study supports that the supply chain system can improve its performance by having more collaborative features. This study provides business practitioners with guidelines to identify the circumstances that the specific collaboration program can fully exploit its advantages.

• The Journal of Industrial Distribution & Business
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• v.14 no.9
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• pp.21-30
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• 2023

Purpose: Focusing on the role of the special contract to collaborate the supply chain operations, this study investigates how the revenue sharing contract affects the performance of Vendor Managed Inventory (VMI). Research design, data, and methodology: The optimization model is formulated to represent two stage supply chain system where the supplier and retailer manage the operations to maximize their own profits. Three supply chain models including the traditional system, VMI, and VMI with revenue sharing contract are compared in the numerical examples. Results: According to the numerical analysis, the entire supply chain system has greater profit under VMI than the traditional system, while VMI alone sacrifices the supplier's profit. With the proper sets of revenue share ratio and wholesale price discount rate, VMI with revenue sharing contract results in the increased profit for both supplier and retailer compared with VMI alone as well as the traditional system. Conclusions: The numerical examples imply that VMI, when it is combined with the revenue sharing contract, can be the effective collaboration program that satisfies every supply chain member. To make VMI with revenue sharing contract to be fair to all supply chain members, they need to agree on the appropriate contract content.

• Journal of the Korea Safety Management & Science
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• v.10 no.3
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• pp.217-225
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• 2008

The inventory routing problem (IRP) is an important area of Supply Chain Management. The objective function of IRP is the sum of transportation cost and inventory cost. We propose an Artificial Immune System(AIS) to solve the IRP. AIS is one of natural computing algorithm. An hyper mutation and an vaccine operator are introduced in our research. Computation results show that the hyper mutation is useful to improve the solution quality and the vaccine is useful to reduce the calculation time.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.4
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• pp.16-21
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• 2002

This paper refer to the trade-off between delivery frequency and amount between supplier and discountstores. Discountstores prefer frequent delivery of small amount because of limited storage space, while suppliers prefer less frequent delivery of large amount in order to save transportation cost In this paper we propose a heuristic algorithm to determine the amount of order and the delivery frequency which decreases the expected length of stockout. We also evaluate various order policies for vendor managed inventory system using simulation with real data.