Browsing by Author "Huang, Wen-Tso"

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An enhanced model for SDBR in a random reentrant flow shop environment
(2014-03-19)
Chang, Yung-Chia
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Huang, Wen-Tso
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工業工程與管理學系
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Department of Industrial Engineering and Management
This study proposed an enhanced simplified drum-buffer-rope (SDBR) model to be applied in a reentrant flow shop (RFS) in which job processing times are generated from a discrete uniform distribution and machine breakdowns are subject to an exponential distribution. In this enhanced SDBR model, the due-date assignment method, order release rule and dispatching rule were improved. The due dates and release dates of orders were determined by considering the total planned load of the capacity-constrained resource (CCR) in a random RFS. The deviation rate of buffer status is used as a dispatching rule to eliminate the influence of machine breakdowns. Simulations based on a real case company are used to evaluate the effective of the proposed model. The experimental results showed that our approach yields better performance than the other methods in terms of six due-date-related indexes when the product mix is with a large proportion of multi-reentrant orders and when the utilisation of CCR increases from 60 to 90%.
Using simplified drum-buffer-rope for re-entrant flow shop scheduling in a random environment
(2011-10-28)
Chang, Yung-Chia
;
Huang, Wen-Tso
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The traditional simplified drum buffer rope (SDBR) does not consider the application of re-entrant flow shop (RFS) in a random environment which might involve variable processing times and machine breakdowns. This paper proposed a weighted layer production buffer and weighted production buffer to monitor the status of the buffer deviation when applying SDBR in a RFS with non-deterministic parameters. The buffer status deviation used the overall urgency and actual urgency to estimate the influence of overall accumulated machine downtime and the influence of actual machine downtime of capacity-constrained-resource (CCR) at different layers. A dispatching rule, called SDBR_D(Reentry), was applied to decide the priority of all work orders by the buffer status deviation of each CCR machine with the consideration of the re-entry feature. A simulated RFS was designed and four different methods (including ours) were applied in order to demonstrate the effectiveness of our approach. The experimental results show that when compared to six performance indexes related to the due date, our approach has better performance than the other three methods when the product mix with a large proportion of multi-reentrant orders and when the CCR utilization increases from 60 to 90%.