작업순서에 종속적인 셋업을 가지는 경우 로트크기 결정과 일정계획에 대한 계층적 해법

Abstract

This research deals with the single machine multi-product capacitated lot sizing and scheduling problem (CLSP) with sequence-dependent setup times and setup costs. The CLSP determines the production quantities and the sequence to satisfy deterministic and dynamic demand during multiple periods. The objective is to minimize the total sum of the inventory holding costs and the sequence-dependent setup costs. We consider the special forms of sequence-dependent setup times, exponential and step function that are the function of product sizes between two adjacent products in sequence. As a solution approach, we propose a two-level hierarchical method consisting of the upper-level planning and the lower-level planning. In the upper-level planning, we solve the lot sizing problem with two estimated sequence-independent setup times based on total average time and sequencing rule, and then solve the scheduling problem given the lot sizing in the lower-level planning. The proposed method compared with the single-level optimal CLSP solution found by commercial optimization software. Finally, the computational experiments show that the two-level method is better than the single-level method in terms of computational time, and the estimation procedure based on sequencing rule outperforms total average time based estimation in terms of the solution quality.