재제조 시스템에서의 동적 로트크기 결정에 관한 연구

Abstract

This thesis considers the problem of determining lot sizes that satisfy time-varying demands of remanufactured products over a given planning horizon with discrete time periods. Remanufacturing, in which used or end-of-life products are restored to like-new condition, generally consists of disassembly, reprocessing and reassembly processes, and hence the lot sizes are determined for each of the three processes. The objective is to minimize the sum of setup and inventory holding costs occurred at the three processes over the planning horizon. To represent the problem mathematically, we suggest a mixed integer programming model that combines the existing ones for disassembly and assembly systems, and prove that the problem is NP-hard by showing that its special case, the disassembly lot sizing problem, is NP-hard. Then, we suggest two dynamic programming based heuristic algorithms, called aggregated and separated heuristics in this thesis. Computational experiments were done on a number of test instances, and the results show that the heuristics give near optimal solutions within a short amount of computation time.