• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.2
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• pp.80-93
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• 2008

This paper improves algorithms for an assembly-type flowshop scheduling problem in which each job is to assemble two types of components and makespan is the objective measure. For the assembly, one type of the components is outsourced with job-dependent lead time but the other type is fabricated in-house. When both components for a job are prepared, the assembly operation for the job can be started. This problem had been proved to be NP-Complete, so branch-and-bound (B&B) and heuristic algorithms have already been developed. In this paper, we suggest other dominance rules, lowerbound and heutistic algorithms. Also, we develop a new B&B algorithm using these improved bound and dominance rules. The suggested heuristics and B&B algorithm are compared with existing algorithms on randomly-generated test problems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.4
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• pp.34-42
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• 2006

This paper considers an assembly-type flowshop scheduling problem in which each job is assembled with two types of components. One type of the components is outsourced with positive lead time but the other type is fabricated in-house at the first stage. The two types of the components should be prepared at the first stage before starting the assembly operation for each job at the second stage. The objective is to schedule the jobs so that the makespan is minimized. Some solution properties and lower bounds are derived and incorporated into a branch and bound algorithm. Also, an efficient heuristic is developed. The performances of the proposed branch and bound algorithm and heuristic are evaluated through computational experiments.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.53-69
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• 1991

This paper is concerned with software developments for scheduling and sequencing of FMS. The scheduling algorithms are developed for 3 types of FMS:single machine type FMS, flowshop type FMS. assembly line type FMS. For the single machine type FMS. full enumeration algorithm is used. For the flowshop type FMS heuristic algorithms are developed. For the assembly type FMS the exsisting PERT/CPM algorithm is applied. Numerical examples are presented for illustration of each algorithm. Each soft ware program list are attached as appendices.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.3
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• pp.1-16
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• 2008

This paper considers a scheduling problem to minimize the total tardiness in the two-stage assembly-type flowshop. The system is composed of multiple fabrication machines in the first stage and a final-assembly machine in the second stage. Each job consists of multiple tasks, each task is performed on the fabrication machine specified in advance. After all the tasks of a job are finished, the assembly task can be started on the final-assembly machine. The completion time of a job is the time that the assembly task for the job is completed. The objective of this paper is to find the optimal schedule minimizing the total tardiness of a group of jobs. In the problem analysis, we first derive three solution properties to determine the sequence between two consecutive jobs. Moreover, two lower objective bounds are derived and tested along with the derived properties within a branch-and-bound scheme. Two efficient heuristic algorithms are also developed. The overall performances of the proposed properties, branch-and-bound and heuristic algorithms are evaluated through numerical experiments.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.45-57
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• 2010

This paper considers a 2-stage assembly flowshop scheduling problem where each job is completed by assembling multiple components. The problem has the objective measure of minimizing total completion time. The problem is shown to be NP-complete in the strong sense. Thus, we derive some solution properties and propose three heuristic algorithms. Also, a mixed-integer programming model is developed and used to generate a lower bound for evaluating the performance of proposed heuristics. Numerical experiments demonstrate that the proposed heuristics are superior over those of previous research.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.2
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• pp.24-28
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• 2004

This paper considers a scheduling problem concerned with an assembly system where two components are first treated In their own parallel machines and then pulled to be assembled into a final product at a single assembly machine. The objective measure is the mean completion time of jobs(a finite number of products). Through characterizing solution properties, we obtain the worst case error bounds of an arbitrary permutation and a SPT based heuristic.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.254-264
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• 2007

This paper considers a scheduling problem to minimize the total weighted completion time in the two-stage assembly-type flowshop. The system is composed of multiple fabrication machines in the first stage and a final-assembly machine in the second stage. Each job consists of multiple components, each component is machined on the fabrication machine specified in advance. The manufactured components of each job are subsequently assembled into a final product on the final-assembly machine. The objective of this paper is to find the optimal schedule minimizing the total weighted completion time of jobs. Three lower bounds are derived and tested in a branch-and-bound (B&B) Procedure. Also, three heuristic algorithms are developed based on the greedy strategies. Computational results show that the proposed B&B procedure is more efficient than the previous work which has considered the same problem as this paper.