Two-stage hybrid flowshop scheduling problem with a product ratio constraint under dynamic job arrivals제품별 구성 비율 제약이 있는 혼합 흐름 공정에서 최대 종료 시간을 최소화하는 스케쥴링 방법 개발
We consider a two-stage hybrid flowshop scheduling problem with a production ratio constraint in the presence of dynamic job arrivals. The first stage is composed of parallel identical machines and there is a single batch processing machine in the second stage. Also, at the batch processing machine product ratio of product types should be satisfied in order to maintain a required yield rate. The batch processing machine can process multiple jobs up to its capacity simultaneously and the processing time is determined by the longest processing time job in the batch. Since it is very difficult to obtain optimal solution for the problem considered in this study in a reasonable amount of time., we present heuristic algorithms for the problem with the objective of minimizing makespan. A forward approach and a backward approach are proposed along with a few scheduling rules employed in each approach, and these are evaluated with a series of computational experiments on randomly generated test problems. The result shows that the heuristics suggested in the study work better than algorithms used in practice.