A Dynamic Production and Transportation Model with Multiple Freight Container Types

Woon-Seek, Lee(이운식) 대한산업공학회 1998 대한산업공학회지 Vol.24 No.1

A Stock Pre-positioning Model to Maximize the Total Expected Relief Demand of Disaster Areas

Woon-Seek Lee,Prudensy Febreine Opit,Byung Soo Kim 대한산업공학회 2011 대한산업공학회 추계학술대회논문집 Vol.2011 No.11

The complexity and uncertainty in performing emergency logistics response require along-term preparation and planning. In this paper, a stock pre-positioning model is considered to support an emergency disaster relief response against the event of earthquake. In this model, a maximum response time limit, budget availability, multiple item types, and capacity restrictions are considered to maximize the total expected relief demand of disaster areas covered by existing distribution centers. The decision of distribution centers to cover a disaster area and the amount of supplies to be stocked in each distribution center are simultaneously determined based on the model. The proposed model is applied to a real case with 33 disaster areas and 16 distribution centers in Indonesia. Then a sensitivity analysis is performed by changing the budgets and the maximum response time.

A Solution to a Dynamic Lot-sizing and Shipping Model with Multiple Freight Container Types Allowed

Woon-Seek, Lee 대한산업공학회 1998 대한산업공학회 춘계학술대회논문집 Vol.1998 No.4

A Stock Pre-positioning Model to Maximize the Total Expected Relief Demand of Disaster Areas

Woon-Seek Lee,Byung Soo Kim,Prudensy Febreine Opit 대한산업공학회 2014 Industrial Engineeering & Management Systems Vol.13 No.3

Stock pre-positioning is one of the most important decisions for preparing the stage of emergency logistics planning. In this paper, a mixed integer model for stock pre-positioning is derived to support an emergency disaster relief response against the event of earthquake. A maximum response time limit, budget availability, multiple item types, and capacity restrictions are considered. In the model, the decision of the distribution centers to cover a disaster area and the amount of supplies to be stocked in each distribution center are simultaneously determined to maximize the total expected relief demand of the disaster areas covered by the existing distribution centers. The proposed model is applied to a real case with 33 disaster areas and 16 distribution centers in Indonesia. Several sensitivity analyses are conducted to estimate the fluctuation on the emergency stock pre-positioning planning by changing the maximum response time and budgets.

A Solution to a Dynamic Lot-sizing and Shipping Model with Multiple Freight Container Types Allowed

Lee, Woon-Seek 한국경영과학회 1998 한국경영과학회 학술대회논문집 Vol.- No.1

This paper considers a single- product lot - sizing and shipping model with discrete time, dynamic demand and finite time horizon, an extension of classical dynamic lot - sizing model. In the model, multiple freight container types are allowed as the transportation mode and each order (product) placed in a period is shipped immediately by containers in the period. Moreover, each container has type- dependent carrying capacity restriction and at most one container type is allowed in each shipping period. The unit freight cost for each container type depends on the size of its carrying capacity. The total freight cost is proportional to the number of each container type employed. Such a freight cost is considered as another set - up cost. It is assumed in the model that production and inventory costs have time- invariably fixed- charge and linear cost functions, respectively, and also backlogging is not allowed. The objective of this study is to determine the optimal lot - sizing policy and the optimal shipping policy simultaneously that minimizes the total system cost to satisfy dynamic demands over a finite time horizon. In the analysis, the optimal solution properties are characterized, based on which a dynamic programming algorithm is derived. T he solution algorithm is then illustrated with a numerical example.

할인구매옵션을 고려한 동적 재생산계획문제

이운식(Woon-Seek Lee) 한국경영과학회 2009 韓國經營科學會誌 Vol.34 No.3

This paper considers a remanufacturing and purchasing planning problem, in which either used products(or wastes) are remanufactured or remanufactured products(or final products) are purchased to satisfy dynamic demands of remanufactured products over a discrete and finite time horizon. Also, as remanufactured products are purchased more than or equal to a special quantity Q, a discount price policy is applied. The problem assumes that the related cost (remanufacturing and inventory holding costs of used products, and the purchasing and inventory holding costs of remanufactured products) functions are concave and backlogging is not allowed. The objective of this paper is to determine the optimal remanufacturing and purchasing policy that minimizes the total cost to satisfy dynamic demands of remanufactured products. This paper characterizes the properties of the optimal policy and then, based on these properties, presents a dynamic programming algorithm to find the optimal policy. Also, a network-based procedure is proposed for the case of a large quantity of low cost used products. A numerical example is then presented to demonstrate the procedure of the proposed algorithm.

동적 블록수송환경을 위한 네트워크 흐름모형 기반의 트랜스포터 일정계획

이운식(Woon-Seek Lee),임원일(Won-Il Lim),구평회(Pyung-Hoi Koo) 대한산업공학회 2008 대한산업공학회 추계학술대회논문집 Vol.2008 No.11

This paper considers a transporter scheduling problem under dynamic block transportation environment in shipbuilding. In dynamic situations, there exist the addition, cancellation or change of block transportation requirements, sudden breakdowns and maintenance of transporters. The transportation of the blocks in the shipyard has some distinct characteristics. Some blocks are available to be picked up at a specific time during the planning horizon while some other blocks need to be delivered before a specific time. These requirements cause two penalty times: 1) delay times incurred when a block is picked up after a required start time, and 2) tardy times incurred when a block shipment is completed after the required delivery time. The blocks are located at different areas in the shipyard and transported by transporters. The objective of this paper is to propose a heuristic algorithm based on a network flow model which minimize the weighted sum of empty transporter travel times, delay times, and tardy times. Also, a rolling-horizon scheduling method is proposed for dynamic block transportation environment. The performance of the proposed heuristic algorithms are evaluated through a simulation experiment.

A Stock Pre-positioning Model to Maximize the Total Expected Relief Demand of Disaster Areas

Lee, Woon-Seek,Kim, Byung Soo,Opit, Prudensy Febreine Korean Institute of Industrial Engineers 2014 Industrial Engineeering & Management Systems Vol.13 No.3

Stock pre-positioning is one of the most important decisions for preparing the stage of emergency logistics planning. In this paper, a mixed integer model for stock pre-positioning is derived to support an emergency disaster relief response against the event of earthquake. A maximum response time limit, budget availability, multiple item types, and capacity restrictions are considered. In the model, the decision of the distribution centers to cover a disaster area and the amount of supplies to be stocked in each distribution center are simultaneously determined to maximize the total expected relief demand of the disaster areas covered by the existing distribution centers. The proposed model is applied to a real case with 33 disaster areas and 16 distribution centers in Indonesia. Several sensitivity analyses are conducted to estimate the fluctuation on the emergency stock pre-positioning planning by changing the maximum response time and budgets.

제3자 물류센터 납품시간창 디스패칭 정책에 관한 효과

이운식(Woon-Seek Lee),김병수(Byung Soo Kim) 한국산업경영시스템학회 2014 한국산업경영시스템학회지 Vol.37 No.1

This paper considers an inbound ordering and outbound dispatching problem for multi-products and multi-vehicles in a third-party distribution center. The demands are dynamic over a discrete and finite time horizon, and replenishing orders are shipped in various transportation modes and the freight cost is proportional to the number of vehicles used. Any mixture of products is loaded onto any type of vehicles. The objective of the study is to simultaneously determine the inbound lot-sizes, the outbound dispatching sizes, and the types and numbers of vehicles used to minimize total costs, which consist of inventory holding cost and freight cost. Delivery time window is one of the general dispatching policies between a third-party distribution center and customers in practice. In the policy, each demand of product for a customer must be delivered within the time window without penalty cost. We derive mixed integer programming models for the dispatching policy with delivery time windows and on-time delivery dispatching policy, respectively and analyze the effect on a dispatching policy with delivery time windows by comparing with on-time delivery dispatching policy using various computational experiments.

폐기물 처분과 유한 재생산률을 고려한 동적 폐기물 회수계획 및 다종제품 재생산계획 문제

이운식(Woon-Seek Lee),노맹석(Maengseok Noh) 한국자료분석학회 2018 Journal of the Korean Data Analysis Society Vol.20 No.1

본 연구는 폐기물을 회수하고 0이거나 유한 재생산률 P 중 하나로 재생산되는 회수 및 재생산 계획 문제를 다룬다. 여기서 재생산률 P는 재생산설비의 일회 재생용량을 나타낸다. 폐기물을 회수하는 데 있어 회수량은 컨테이너 용기의 크기인 W 단위로 회수되며 폐기물 회수수익은 컨테이너 용기의 사용대수에 비례한다. 각 기간 말에 남아있는 폐기물 재고량은 처분될 수 있으며 이때 처분비용이 발생된다. 계획하는 기간 동안 각각의 다종제품 수요는 매 기간 동적으로 발생하며 각 재생품의 재생산량은 폐기물 투입량의 일정한 비율(0<α_{i}<1)로 산출된다. 또한, 연속적으로 발생하는 재생산 기간들의 제일 첫 번째 재생산 시점에서만 부과되는 설비시동비용이 발생된다. 관련비용함수(폐기물 및 재생품 재고비용, 재생품 재생산비용)는 오목함수를 가지며 추후조달은 허용되지 않는다. 본 연구의 목적은 폐기물 처분을 고려한 폐기물의 회수계획 뿐만 아니라, 재생산률이 유한할 때 다종 제품들의 재생산계획을 함께 결정되는 최적의 회수계획 과 재생산계획을 수립하는 데 있다. 이를 위해, 회수계획과 재생산계획을 함께 수립되는 수리모형과 이를 통한 최적해의 특성을 규명한다. 규명된 성질을 기반으로 최적해 탐색 알고리즘인 동적계획법 알고리즘을 제안하고자 한다. 또한(u,v)-부문제에 대한 효율적으로 최적해를 구할 수 있는 네트워크 기반 알고리즘을 제안한다. 수치예제를 통해 제안된 알고리즘의 적용절차를 소개한다. In this paper, we consider withdrawing and remanufacturing planning problems, where wastes can be withdrew at a period and also remanufactured at a period by any value in the set {0, P}. Here, the rate P is the capacity of a remanufacturing facility. The withdrawal fee is occurred as a profit term that is proportional to the withdrawing container size(W). The inventory amounts of wastes can be disposal at the end of a period by incurring a disposal cost. With each a fixed portion (0<α_i<1) in the input wastes, the multiple products are remanufactured to satisfy dynamic demands. Also, a start-up cost is only incurred at the first period of a remanufacturing block which is consecutively remanufactured. We assumed that the related cost (inventory holding cost of the wastes, the remanufactured products’ cost for remanufacturing and inventory holding) functions are concave and specially we do not allow backlogging. In this paper, we determine simultaneously the optimal withdrawing and remanufacturing plans by minimizing total cost. This total cost was satisfied by dynamic demands for the multiple products. The optimal properties for solutions are clarified and a dynamic programming algorithm is suggested to find the optimal plan based on these properties. Finally we proposed a network model to find an efficient optimal solution for (u,v)-subproblems.