제한된 주문허용 수준을 갖는 주문생산 재고시스템을 위한 민감도 분석

김은갑,김지승 한국경영과학회 2005 한국경영과학회지 Vol.30 No.2

This paper considers a make-to-order inventory-production system in which customer orders are admitted only when the number of outstanding customer orders is below a value committed by the system. We deal with general distributions for the customer order inter-arrival, production, and replenishment lead time processes. Monotonicities of the optimal average cost with respect to these distribution parameters are established using sample path coupling arguments. When distributions are given as an exponential one, we implement a sensitivity analysis on the optimal inventory policy and show that it has monotonicities with respect to system costs using dynamic programming.

Optimal production and admission policy in a make-to-order system with two customer classes

김은갑 한국SCM학회 2015 한국SCM학회지 Vol.15 No.2

This paper considers a manufacturer that produces two types of MTO products. We study the optimal policy for admission control and production sequencing. Using the average cost Markov decision process model, we identify the optimal policy by three monotonic switching curves. We show that there exist a backlog level which always rejects incoming customer orders. We also prove that the optimal switching curves are monotonically shifted by the change of order rejection penalties.

Optimal Control for Cash Management with Investment and Retrieval

김은갑,변진호,배재현 대한산업공학회 2011 산업공학 Vol.24 No.4

We develop a cash management model in which firms face randomly occurred investment projects and retrieve investments upon the maturity of these projects. Using the Markov Decision Problem approach, we examine a control policy which dynamically adjusts the cash balance under the discounted cost criterion. The existence of an optimal policy is shown under some conditions. The optimal solution procedure is developed to find the optimal points and the optimal sizes for adjusting the cash balance. In numerical experiment, we investigate important structural properties of the optimal cash management policy.

조세범 처벌에 관한 문제점 및 개선방안

김은갑 서울市立大學校 經商大學 稅務學科 2004 稅務學論集 Vol.17 No.1

조세범 처벌에 관한 문제점 및 개선안

The Effects of Lead Time Variability on Managing Component Replenishment for Customized Manufacturing

김은갑 한국생산관리학회 2010 韓國生産管理學會誌 Vol.21 No.3

We study the impact of lead time variability on inventory management in a make-to-order system that processes customized manufacturing using a common component. Components are purchased from a supplier with Erlang lead times. In this paper, we investigate the structure of the optimal replenishment policy and examine how the lead time variability affects replenishment decision and supply chain cost. Explicit incorporation of setup cost and lead time variability into the model is the essential contribution to the current literature. To provide better managerial insights on the problem, we perform numerical experiment under different operating conditions of the system parameters.

Customer Order Admission Control and Inventory Management in a Make-to-order System - The Effects of Replenishment Setup Cost

김은갑 한국산업경영학회 2010 경영연구 Vol.25 No.1

We study the customer order admission control and inventory management decision in a make-to-order system that processes customer orders using common component. Each incoming customer order can be accepted or rejected based on the system status. The component is purchased from a supplier under stochastic lead times and setup costs. In this paper, we investigate the structure of joint admission and inventory control and examine the impact of setup cost on it. To provide a better understanding of the structure of the optimal policy, we compared its performance with two heuristic policies; the one with static admission control and dynamic replenishment control and the other with static admission and replenishment controls. The paper contributes to the current literature of make-to-order production-inventory systems in the following two essential aspects. First, we study the problem of simultaneously considering admission control and inventory management decisions. Second, we explicitly incorporate the replenishment setup cost into the model and examine its impact on the optimal cost function and the optimal policy.

주문인도기간 변동성이 제품 및 부품 시장 수요를 갖는 제조 기업의 수익 관리에 미치는 영향 분석

김은갑 한국산업경영학회 2014 경영연구 Vol.29 No.1

본 논문은 계획 생산 방식으로 제품을 생산하는 제조 기업이 제품 수요와 부품 수요를 동시에 갖는 상황을 다루고 있다. 제품 생산에 필요한 부품은 공급업체로부터 조달받으며, 주문인도기간은 Erlang분포를 따른다. 확보된 부품은 제품 생산뿐만 아니라 부품 시장 수요를 위해 사용되어져야 한다. 따라서 제조 기업은 부품 재고를 배급해야 하는 문제에 직면하게 된다. 또한, 재고 배급 문제 이외에도 기업은 제품 생산과 부품 보충을 위한 의사 결정을 해야 한다. 본 논문은 주문인도기간 변동성이 제품 생산, 부품 보충, 그리고 부품 수요 통제 전략에 미치는 영향을 분석하였다. 또한, 본 논문은 수치 실험을 통해 주문인도기간의 변동성이 기업의 수익과 주문량에 미치는 영향을 분석하였다. This paper considers a make-to-stock firm that has both product and component demands. Components required in manufacturing products are acquired from the supplier whose lead time process follows an Erlang distribution. In addition to the internal demand from the MTS production, the firm faces demands from the component market, which raises the issue of inventory rationing. In addition to this, the firm also faces the decision of production and inventory replenishment. This paper examines how the lead time variability can affect the MTS production, component replenishment, and component demand controls. This paper also investigates the impact of lead time variability on the firm's profit via a numerical experiment and studies how the optimal average profit and the optimal order quantity are changed by the lead time variability.

두 단계 푸쉬-풀 공급망에서 공급자 주도 재고 관리의 구현 - 가변 생산량이 갖는 영향을 중심으로

김은갑 한국SCM학회 2010 한국SCM학회지 Vol.10 No.2

We consider a supply chain with a component manufacturer and a customized end item manufacturer in stage under a vendor-managed inventory (VMI) agreement. The component manufacturer continuously reviews both component inventory and backorder status at the end item manufacturer. Based on this information, the component manufacturer dynamically determines production scheduling and lot size which is the multiple of the basic lot size. The goal of this paper is to find the component manufacturer's production policy which minimizes the total supply chain cost. From numerical experiment, we investigate the impact of the variable production lot size on the supply chain cost.

경쟁 기반의 부품 생산과 협업 기반의 완성품 생산 시스템에서 생산과 수요 통제의 통합적 고찰

김은갑 대한산업공학회 2009 산업공학 Vol.22 No.4

This paper considers a two-stage supply system consisting of two make-to-stock facilities. The facility in the first stage produces a single type of component in anticipation of future demands from the market and the end item production while the facility in the second stage produces the end item in anticipation of future demands from the OEM customers. The facility in the first stage has the option of to accept or reject each incoming demand from the market. In this paper, we address the problem of how to control the exogenous component demand and how to manage the production of the end item and the component so as to maximize the system’s profit subject to the system costs. In this paper, we present a heuristic policy that is the base-stock production policy combined with a linear switching curve for component demand control. Numerical study is implemented under different operating conditions of the system and it shows that the performance of the heuristic is very promising compared to that of the optimal policy for the Markov model.

Component Outsourcing Contracts in a Two-Component Assembly System

김은갑 대한산업공학회 2009 산업공학 Vol.22 No.2

This paper considers a two-component assembly system that makes different types of purchasing contracts by component type and studies the issue of coordinating those contracts. Acquisition of type 1 component is based on the long-term contract. In contrast, type 2 component is intermittently purchased under the sort-term contract. We identify the structural properties of the optimal short-term contract and investigate how the changes in system parameters affect the optimal performance. To provide managerial insights, we compare the short-term and long-term contracts for type 2 component and discuss the conditions that make the short-term contract preferable to the long-term contract. We also present a result which shows that coordinating the contracts of type 1 and type 2 components can be significantly profitable over uncoordinating them.