Browsing by Author "Sha, DY"

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A common buffer-based approach to buffer management for a wafer fabrication factory
(1998-09-01)
Huang, JY
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Sha, DY
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工業工程與管理學系
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Department of Industrial Engineering and Management
This paper presents a buffer management method for a wafer fabrication factory. A pull-based production control system (PPCS) is adopted to handle production activity control (PAC) and reduce the work-in-progress (WIP) level. In addition, a common buffer approach is used to further control WIP conditions and utilize limited storage space effectively. Simulation results show that the proposed buffer management method significantly reduces buffer storage space. Besides, it also maintains the manufacturing system's performance roughly equal to that provided by a local buffer scheme. Significance: The proposed buffer management method can handle production activity control, reduce the WIP level, control WIP conditions, and effectively utilize limited storage space. In addition, the method is easy to implement in a practical application.
A design approach to the multi-objective facility layout problem
(1999-03-20)
Chen, CW
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Sha, DY
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工業工程與管理學系
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Department of Industrial Engineering and Management
A new multi-objective heuristic algorithm for resolving the facility layout problem is presented in this paper. It incorporates qualitative and quantitative objectives and resolves the problem of inconsistent scales and different measurement units. We consider suboptimal solutions since optimal methods are computationally unfeasible to large layout problems. In this paper, we develop the dominant index (DI) and incorporate it in our heuristic algorithm to guarantee the quality of proposed solutions. Moreover, a new measure of solution quality, dominant probability (D-p), is offered to determine the probability that one layout is better than the others. Computational results show that our proposed heuristic algorithm is an efficient method for obtaining good-quality solutions.
A simulated annealing algorithm for integration of shop floor control strategies in semiconductor wafer fabrication
(2003-09-01)
Sha, DY
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Liu, CY
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工業工程與管理學系
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Department of Industrial Engineering and Management
The semiconductor manufacturing industry is one of the most important industries in Taiwan. Wafer fabrication is an essential process in semiconductor manufacturing. However, controlling the production system on the shop floor is extremely difficult owing to the complicated manufacturing process and reentrant characteristics. In this paper, the shop floor control (SFC) integration strategies (order review/release, dispatching, and rework strategies) in wafer fabrication are considered with using several performances. We reviewed the literature on SFC strategies in wafer fabrication. The proposed combination simulation and simulated annealing (SA) algorithm is presented for SFC strategies in wafer fabrication. The objective was to seek the near global optimum solution for the combination of SFC strategies for a specific performance indicator. From the results, the proposed methodology was found to perform well for combinations of SFC strategies using different performance indicators in wafer fabrication. However, no single combination of SFC strategies could satisfy all performance indicators. Hence, considering the trade-off among these production control strategies, a suitable strategy should be chosen based on the system control tactics. Considerable computational time was saved in this research.
Constructing procedures of an effective production activity control technique for a wafer fabrication environment
(1998-09-01)
Huang, JY
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Sha, DY
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工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper presents a flexible production activity control (PAC) technique for a wafer fabrication factory. To resolve PAC problems in extremely complicated wafer fabrication processes, the proposed pull-based production control system (PPCS) integrates concepts of the conventional pull (kanban) system, push system, and drum-buffer-rope (DBR) scheduling technique. A kanban number calculating algorithm is also derived in which the kanban number calculated functions as an initial solution of the simulation run to obtain the optimal solution. Simulation results demonstrate that the PPCS yields a better performance than the conventional pull system and push system. Significance: Wafer fabrication is the most important but complicated process in the semiconductor manufacturing industry. The PPCS proposed herein simultaneously increases key machine utilization and decreases the WIP inventory level of a wafer fabrication factory, thereby fulfilling the PAC task.
Due date assignment using artificial neural networks under different shop floor control strategies
(2004-05-01)
Hsu, SY
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Sha, DY
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工業工程與管理學系
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Department of Industrial Engineering and Management
Due date assignment (DDA) is the first important task in shop floor control. Due date-related performance is impacted by the quality of the DDA rules. Assigning order due dates and delivering the goods to the customer on time will enhance customer service and provide a competitive advantage. A new methodology for lead-time prediction, artificial neural network (ANN), is adopted to model new due date assignment rules. An ANN-based DDA rule, combined with simulation technology and statistical analysis, is presented. Whether or not the ANN-based DDA rule can outperform the conventional and Reg-based DDA rules taken from the literature is examined. The interactions between the DDA, order review/release (ORR), and dispatching rules significantly impact upon one another, and it is therefore very important to determine a suitable DDA rule for the various combinations of ORR and dispatching rules. From the simulation and statistical results, the ANN-based DDA rules perform better in due date prediction. The ANN-based DDA rules have a smaller tardiness rate than the other rules. ANN-based DDA rules have a better sensitivity and variance. Therefore, if system information is not difficult to obtain, the ANN-based DDA rule can perform a better due date prediction. This paper provides suggestions for DDA rules under various combinations of ORR and dispatching rules. ANN-Sep is suitable for most of these combinations, especially when ORR, workload regulation (WR) and two boundaries (TB), rules are adopted.
Due-date assignment in wafer fabrication using artificial neural networks
(2004-05-01)
Sha, DY
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Hsu, SY
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工業工程與管理學系
;
Department of Industrial Engineering and Management
Due-date assignment (DDA) is the first important task of shop floor control in wafer fabrication. Due-date related performance is impacted by the quality of the DDA rules. Assigning order due dates and timely delivering the goods to the customer will enhance customer service and competitive advantage. A new methodology for lead-time prediction, artificial neural network (ANN) prediction is considered in this work. An ANN-based DDA rule combined with simulation technology and statistical analysis is developed. Besides, regression-based DDA rules for wafer fabrication are modelled as benchmarking. Whether neural networks can outperform conventional and regression-based DDA rules taken from the literature is examined. From the simulation and statistical results, ANN-based DDA rules perform a better job in due-date prediction. ANN-based DDA rules have a lower tardiness rate than the other rules. ANN-based DDA rules have better sensitivity and variance than the other rules. Therefore, if the wafer fab information is not difficult to obtain, the ANN-based DDA rule can perform better due-date prediction. The SFM_sep and JIQ in regression-based and conventional rules are better than the others.
Heuristic algorithm for the design of facilities layout and AGV routes in tandem AGV systems
(1997-03-01)
Hsieh, LF
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Sha, DY
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交大名義發表
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工業工程與管理學系
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National Chiao Tung University
Considering the necessity for the integrated design of facilities layout and material handling systems, this paper develops a heuristic algorithm to solve the facilities layout and AGV routes problems simultaneously in a tandem automated guided vehicle (AGV) system. A tandem AGV system is composed of several nonoverlapping closed loops; each loop is traversed by a vehicle. Based on this system in which bi-directional vehicles are used, distance and material now between pickup/deposit stations are considered simultaneously during the design of the facilities layout. In the meantime, several transit stations would handle the transportation between loops. As its subject, this paper proposes a heuristic algorithm to implement the facilities layout within each loop and the route of each vehicle in order to reduce the material handling cost It is proved that the heuristic algorithm is polynomial time complexity with O(n(4)).
Heuristic algorithm for the design of facilities layout and AGV routes in tandem AGV systems
(1997-03-01)
Hsieh, LF
;
Sha, DY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Considering the necessity for the integrated design of facilities layout and material handling systems, this paper develops a heuristic algorithm to solve the facilities layout and AGV routes problems simultaneously in a tandem automated guided vehicle (AGV) system. A tandem AGV system is composed of several nonoverlapping closed loops; each loop is traversed by a vehicle. Based on this system in which bi-directional vehicles are used, distance and material now between pickup/deposit stations are considered simultaneously during the design of the facilities layout. In the meantime, several transit stations would handle the transportation between loops. As its subject, this paper proposes a heuristic algorithm to implement the facilities layout within each loop and the route of each vehicle in order to reduce the material handling cost It is proved that the heuristic algorithm is polynomial time complexity with O(n(4)).
Heuristic approach for solving the multi-objective facility layout problem
(2005-11-01)
Chen, CW
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Sha, DY
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工業工程與管理學系
;
Department of Industrial Engineering and Management
A new heuristic approach for the generation of preferred objective weights to solve the multi-objective facility layout problem is presented. By applying a multi-pass halving and doubling procedure, a paired comparison method based on the strength of preference among objectives given by the decision-maker is developed. Furthermore, a 'prior test' is proposed to examine the consistency of the paired comparison matrix. An efficient method to transform the inconsistent matrix into a consistent one so the result can closely approximate the decision-maker's original assessments is also offered. The geometric mean method is then employed to obtain the objective weights and the final solution. There are five phases in the proposed heuristic approach. The first generates a basic solution; the second involves constructing a paired comparison matrix by using the multi-pass halving and doubling procedure; the third identifies the consistency of the paired comparison matrix; the fourth transforms the inconsistent matrix into a consistent one; and the fifth generates the preferred weights and obtains the facility layout solution. An illustrative example is given to demonstrate an application of the proposed approach for solving the multi-objective facility layout problem.
Using data mining for due date assignment in a dynamic job shop environment
(2005-06-01)
Sha, DY
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Liu, CH
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工業工程與管理學系
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Department of Industrial Engineering and Management
Due date assignment is an important task in shop floor control, affecting both timely delivery and customer satisfaction. Due date related performances are impacted by the quality of the due date assignment methods. Among the simple and easy to implement due date assignment methods, the total work content ( TWK) method achieves the best performance for tardiness related performance criteria and is most widely used in practice and in study. The performance of the TWK method can be improved if the due date allowance factor k could render a more precise and accurate flowtime estimation of each individual job. In this study, in order to improve the performance of the TWK method, we have presented a model that incorporated a data mining tool - Decision Tree - for mining the knowledge of job scheduling about due date assignment in a dynamic job shop environment, which is represented by IF-THEN rules and is able to adjust an appropriate factor k according to the condition of the shop at the instant of job arrival, thereby reducing the due date prediction errors of the TWK method. Simulation results show that our proposed rulebased TWK due date assignment ( RTWK) model is significantly better than its static and dynamic counterparts ( i.e., TWK and Dynamic TWK methods). In addition, the RTWK model also extracted comprehensive scheduling knowledge about due date assignment, expressed in the form of IF-THEN rules, allowing production managers to easily understand the principles of due date assignment.
Virtual integration with a multi-criteria partner selection model for the multi-echelon manufacturing system
(2005)
Sha, DY
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Che, ZH
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工業工程與管理學系
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Department of Industrial Engineering and Management
Virtual integration (VI) offers a way to make manufacturing systems more agile and competitive. VI integrates the production resources of many manufacturing systems (partners) efficiently, and that leads to a rapid response to market changes. Based on the VI concept these partners throughout the world will form a virtual enterprise; (VE). Thus to select partners is the essential and the most important issue. The main objective of this paper is to develop a partner selection and production-distribution planning with the novel partner selection model, based on the analytic hierarchy process (AHP) methodology, multi-attribute utility theory (MAUT) and integer programming (IP), for the VI with multiple criteria. The AHP and MAUT methods are use to assess and set weights for each partner candidate and the IP model applies these weights to find the optimal partners from the potential ones and provide the suitable production-distribution plan to the elective partners. Finally, a case study has been provided to substantiate a feasible quality solution of the proposed model.
Wafer rework strategies at the photolithography stage
(2001-06-01)
Sha, DY
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Hsieh, LF
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Chen, KJ
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工業工程與管理學系
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Department of Industrial Engineering and Management
Defective wafers are often seen during the semiconductor manufacturing process. Technically, there is no known remedy for a defective wafer. However, at the photolithography phase of semiconductor manufacturing, the defective wafers can be reworked to reduce the manufacturing cost significantly. In this paper, when comparing the three rework strategies that were proposed by Zargar, we pinpoint the disadvantages of each and offer two other strategies. We assess the advantages and disadvantages of the five rework strategies of each reworked batch according to total cycle time, the quantity of work-in-process, each machine's utilization rate, the utilization rate of photolithography, and the average length of queues for photolithography. Through simulations and statistics, the fifth strategy is shown to be superior to the first four and most suitable for wafer manufacturing. Significance: At the photolithography stage, the processing relation between lot and lot should be considered. Thus, how to schedule reworking in order to reduce the effect on waiting lots is a crucial issue for wafer manufacturing management.