Browsing by Author "Chung, Shu-Hsing"

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A DEA window analysis on the product family mix selection for a semiconductor fabricator
(2008-07-01)
Chung, Shu-Hsing
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Lee, Amy Hsin-I
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Kang, He-Yau
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Lai, Chih-Wei
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工業工程與管理學系
In a competitive market, semiconductor fabricator must face an environment with multi-product types, multi-priority orders and demand changes in time. Since semiconductor fabrication has a very complicated production process, the above-stated characteristics make the production planning even more difficult. This paper applies data envelopment analysis (DEA) to find a set of product family mix that is efficient for the company to produce. To ensure long-term effectiveness in productivity and in profit gaining, window analysis is adopted to seek the most recommended set of product family mixes for manufacturing by measuring the performance changes over time. With this method, the performance of a mix in one period is compared not only with the performance of other mixes but also with its own performance in other periods. The proposed mechanism can provide guidance to the fabricator regarding strategies for aggregate planning so as to improve manufacturing efficiency. (c) 2007 Elsevier Ltd. All rights reserved.
A scenario-based stochastic programming model for the control or dummy wafers downgrading problem
(2009-05-01)
Chung, Shu-Hsing
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Yang, Yi-Shu
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工業工程與管理學系
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Department of Industrial Engineering and Management
The subject of this paper is to Study a realistic planning environment in wafer fabrication for the control or dummy (C/D) wafers problem with uncertain demand. The demand of each product is assumed with a geometric Brownian motion and approximated by a finite discrete set of scenarios. A two-stage stochastic programming model is developed based oil scenarios and solved by a deterministic equivalent large linear programming model. The model explicitly considers the objective to minimize the total cost of C/D wafers. A real-world example is given to illustrate the practicality of a stochastic approach. The results are better in comparison with deterministic linear programming by using expectation instead of stochastic demands. The model improved the performance of control and dummy wafers management and the flexibility of determining the downgrading policy. Copyright (C) 2008 John Wiley & Sons, Ltd.
A simulated annealing algorithm for manufacturing cell formation problems
(2008-04-01)
Wu, Tai-Hsi
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Chang, Chin-Chih
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Chung, Shu-Hsing
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工業工程與管理學系
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Department of Industrial Engineering and Management
The cell formation problem determines the decomposition of the manufacturing cells of a production system in which machines are assigned to these cells to process one or more part families so that each cell is operated independently and the intercellular movements are minimized or the number of parts flow processed within cells is maximized. In this study, a simple yet effective simulated annealing-based approach, SACF, is proposed to solve the cell formation problem. Considerable efforts are devoted to the design of parts and machine assignment procedures to direct SACF to converge to solutions with good values of grouping efficacy. A set of 25 test problems with various sizes drawn from the literature is used to test the performance of the proposed heuristic algorithm. The corresponding results are compared to several well-known algorithms published. The comparative study shows that the proposed SACF algorithm improves the grouping efficacy for 72% of the test problems. The proposed algorithm should thus be useful to both practitioners and researchers. (C) 2007 Elsevier Ltd. All rights reserved.
A water flow-like algorithm for manufacturing cell formation problems
(2010-09-01)
Wu, Tai-Hsi
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Chung, Shu-Hsing
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Chang, Chin-Chih
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工業工程與管理學系
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Department of Industrial Engineering and Management
Available research on the manufacturing cell formation problem shows that most solution approaches are either single- or multiple-solution-agent-based, with a fixed size of solution agents. Frequent problems encountered during the process of solving the cell formation problem include solutions being easily trapped in local optima and bad solution efficiency. Yang and Wang [Yang, F.-C., Wang, Y.-P., 2007. Water flow-like algorithm for object grouping problems. journal of the Chinese Institute of Industrial Engineers, 24(6). 475-488] proposed the water flow-like algorithm (WFA) to overcome the shortcomings of single- and multiple-solution-agent-based algorithms. WFA has the features of multiple and dynamic numbers of solution agents, and its mimicking of the natural behavior of water flowing from higher to lower levels coincides exactly with the process of searching for optimal solutions. This paper therefore adopts the WFA logic and designs a heuristic algorithm for solving the cell formation problem. Computational results obtained from running a set of 37 test instances from the literature and newly created have shown that the proposed algorithm has performed better than other benchmarking approaches both in solution effectiveness and efficiency, especially in large-sized problems. The superiority of the proposed WFACF over other approaches from the literature should be attributed to the collaboration of the WFA logic, the proposed prior estimation of the cell size, and the insertion-move. The WFA is a novel heuristic approach that deserves more attention. More attempts on adopting the WFA logic to solve many other combinatorial optimization problems are highly recommended. (C) 2010 Elsevier B.V. All rights reserved.
An efficient tabu search algorithm to the cell formation problem with alternative routings and machine reliability considerations
(2011-02-01)
Chung, Shu-Hsing
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Wu, Tai-Hsi
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Chang, Chin-Chih
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工業工程與管理學系
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Department of Industrial Engineering and Management
Cell formation is the first step in the design of cellular manufacturing systems. In this study, an efficient tabu search algorithm based on a similarity coefficient is proposed to solve the cell formation problem with alternative process routings and machine reliability considerations. In the proposed algorithm, good initial solutions are first generated and later on improved by a tabu search algorithm combining the mutation operator and an effective neighborhood solution searching mechanism. Computational experiences from test problems show that the proposed approach is extremely effective and efficient. When compared with the mathematical programming approach which took three hours to solve problems, the proposed algorithm is able to produce optimal solutions in less than 2 s. (C) 2010 Published by Elsevier Ltd.
Analyzing the effects of family-based scheduling rule on reducing capacity loss of single machine with uncertain job arrivals
(2012-01-01)
Chung, Shu-Hsing
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Yang, Ming-Hsien
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Kao, Ching-Kuei
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工業工程與管理學系
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Department of Industrial Engineering and Management
For a single finite-capacity machine that can process several product types of jobs, uncertainties in job arrival time and product type can make the calculation of required setup time and the setting of output target very complicated. Setup activities may cause wastage in machine capacity and extend job lead time. In such circumstances, the family-based scheduling rule (FSR) can be used to reduce setup frequency and amount of setup time. To efficiently evaluate the effects on capacity-saving, both expected setup time and service time are estimated by the FSR analytic models. The effect of FSR in reducing setup time and capacity loss is explored further by comparing the results with FIFO rule. Finally, the performances of the developed analytic models for estimating setups and setup time are evaluated in the experimental design, and a simulation model is built for accuracy comparisons with the analytic models. (C) 2011 Elsevier Ltd. All rights reserved.
Capacity pricing mechanism for wafer fabrication
(2008-10-01)
Chung, Shu-Hsing
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Lee, Amy H. I.
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Huang, Chun-Ying
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Chuang, Chia-Chien
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工業工程與管理學系
Wafer fabrication is perhaps the most capital-intensive and technology-intensive industry. Due to customer demand uncertainty, the wafer fabrication industry in Taiwan became dramatically competitive. Emergency orders demanded from customers may exist for the need of time-to-market. How to respond to emergency orders from customers, to analyze the impact to production and cost, and to design an appropriate order acceptance plan, have become an important task for enterprises in pursuing higher service quality and ultimate profit maximization. In this paper, we propose a capacity pricing mechanism to evaluate the impacts of emergency orders. The mechanism is constructed under the circumstances that master production scheduling (MPS), capacity requirement planning (CRP), and data for manufacturing costs are known. Through production planning and profit analysis, the mechanism can analyze pricing factors including the process plans of products, priority levels of products, urgency of orders, and number of layers of poly and metal, so as to reflect the length of cycle time, waiting-time savings, impact to cycle time variance of all orders, and usage amount of critical resources. The capacity price for each product type under each priority level can be determined as a result. (C) 2008 Elsevier Ltd. All rights reserved.
Collaborative production-distribution planning for semiconductor production turnkey service
(2007)
Chung, Shu-Hsing
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Chung, I-Ping
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Lee, Amy H. I.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Semiconductor production turnkey service (SPTS) coordinates wafer fabrication with the outsourcing of the remaining processes including circuit probing testing (C/P testing), integrated circuit (IC) assembly and final testing for buyers. To reduce the production cost and lead time in the supply chain, wafer fabricators must be responsible for the production and distribution planning for the SPTS. Therefore, this research develops an integer-programming (IP) -based model of collaborative production-distribution planning. Under this model, multi-products, multi-stages, and multi-outsourcing factories with different processing capabilities are considered. However, the IP model cannot solve the problem within a polynomial time when the problem becomes as complicated as those in real practice. To confront this problem, we adopt and modify the generalized saving algorithm (GSA) so that the proposed algorithm can solve complicated real-world problems efficiently. The numerical results show that the proposed algorithm can significantly increase the solving efficiency.
Heuristic algorithms to solve the capacity allocation problem in photolithography area (CAPPA)
(2008-06-01)
Chung, Shu-Hsing
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Huang, Chun-Ying
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Lee, Amy H. I.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Wafer fabrication is one of the most complex and high competence manufacturing. How to fully utilize the machine capacity to meet customer demand is a very important topic. In this paper, we address the capacity allocation problem for photolithography area (CAPPA), which belongs to a capacity requirement planning scheme, with the process window and machine dedication restrictions that arise from an advanced wafer fabrication technology environment. Process window means that a wafer needs to be processed on machines that can satisfy its process capability (process specification). Machine dedication means that once the first critical layer of a wafer lot is processed on a certain machine, the subsequent critical layers of this lot must be processed on the same machine to ensure good quality of final products. We present six modified heuristics and a linear-programming-based heuristic algorithm (LPBHA) to solve the problem efficiently. The performance of the proposed algorithms is tested using real-world CAPPA cases taken from wafer fabrication photolithography area. Computational results show that LPBHA is the most effective one, and with a least average and a least standard deviation of deviation ratio of 0.294 and 0.085% compared to the lower bound of the CAPPA.
Hybrid simulated annealing algorithm with mutation operator to the cell formation problem with alternative process routings
(2009-03-01)
Wu, Tai-Hsi
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Chung, Shu-Hsing
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Chang, Chin-Chih
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工業工程與管理學系
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Department of Industrial Engineering and Management
In this study, a hybrid simulated annealing algorithm with mutation operator is proposed to solve the manufacturing cell formation problem considering multiple process routings for parts, so that either the intercellular movements are minimized or the grouping efficacy is maximized, depending on the definition of the decision objective. The proposed algorithm is designed mainly to explore solution regions efficiently and to expedite the solution search process. The performance of the proposed algorithm is tested by a range of test problems, some of which are from the literature and some of which are generated within this study. The comparative study shows that the proposed algorithm improves the best results found in the literature for 28.6% of the test problems and the percentages of improvement are even higher than 18% in several test instances. (C) 2008 Elsevier Ltd. All rights reserved.
Interim equipment shutdown planning for a wafer fab during economic downturns
(2010-11-01)
Chung, Shu-Hsing
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Hsieh, Ming-Hsiu
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工業工程與管理學系
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Department of Industrial Engineering and Management
Because of the low equipment utilization during periods of economic recession, managers of wafer labs are forced to plan equipment shutdowns in order to reduce variable cost and reallocate resources. Unfortunately, few studies have proposed effective solutions for equipment shutdown planning in response to economic downturns. Taking into consideration the product mix, corresponding output target, excessive capacity, production performance impact and the variable cost savings, this paper presents a new mechanism for equipment shutdown planning using a developed integer programming model. The proposed mechanism effectively provides valuable recommendations for the managements of wafer fabs regarding the type and quantity of equipment to shut down. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
Job releasing and throughput planning for wafer fabrication under demand fluctuating make-to-stock environment
(2006)
Chung, Shu-Hsing
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Lai, Chun-Mei
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工業工程與管理學系
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Department of Industrial Engineering and Management
In the semiconductor industry, dynamic changes in demand force companies changing the product mix makes the production planning challenging. This paper aims at an environment where product mix changes periodically and presents a production scheduling system to plan the wafer lot release and throughput. The proposed system is designed on the make-to-stock basis with the objective of meeting demand forecast while maintaining production smoothness. Two modules are included in the system. Preliminary analysis module analyzes throughput and cycle time distributions for different product mixes so as to determine relative parameters to be used as the inputs to the job releasing plan. In the production scheduling module, with the considerations of the attainment of demand forecast, production smoothness, and commitment of the due dates of the released job orders, the job release schedule and completion time table are prepared. A simulation model of a semiconductor fab is used as the base case to demonstrate the effectiveness and efficiency of the proposed system.
Long-term tool elimination planning for a wafer fab
(2008-04-01)
Chung, Shu-Hsing
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Hsieh, Ming-Hsiu
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工業工程與管理學系
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Department of Industrial Engineering and Management
Wafer manufacturers must make decisions regarding tool elimination due to changes caused by demand, product mixes, and overseas fab capacity expansion. Such a problem is raised by leading semiconductor manufacturers in Taiwan. This paper is aimed at developing a sound mechanism for tool portfolio elimination based on determining which equipment can be pruned. In the proposed mechanism, product mix, wafer output, capital expenditure, tool utilization, protective capacity, and cycle time are taken into the overall evaluation. This paper develops an integer programming model to avoid trial-and-error and to obtain the optimal solution. Compared to the current industry approach, the results show that the proposed mechanism can effectively identify the correct tools for elimination with a large capital savings and little cycle time impact. (C) 2007 Elsevier Ltd. All rights reserved.
Measuring production performance of different product mixes in semiconductor fabrication
(2006-03-01)
Chung, Shu-Hsing
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Pearn, Wen Lea
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Lee, Amy H. I.
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工業工程與管理學系
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Department of Industrial Engineering and Management
In a competitive market, a company needs to fully utilize its current capacity in order to acquire higher profit. The purpose of this paper is to present an effective approach to find a set of product mix efficient for the company to achieve the optimal production. Simulation is first used to generate the data of performance measures of different product mixes in a semiconductor fabricator. Data Envelopment Analysis (DEA) is applied next to measure multiple inputs and outputs, without pre-assigning weights, for product mixes, and an efficiency score for producing each product mix relative to other mixes can be obtained. The results provide guidance for a fab in accepting orders when its capacity cannot fully satisfy all the product demand. Significance: This paper applied the DEA method to evaluate the production performance with different product mixes in a semiconductor fabricator. The results provide guidance to the fabricator regarding accepting orders to maximize the production efficiency and the profit, while considering several other important input and output factors that maintain production smoothing.
Modeling the Master Production Scheduling System with Downgraded Products for a TFT-LCD Module Factory
(2012-01-01)
Lin, Chun-Cheng
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Kang, Jia-Rong
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Liu, Wan-Yu
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Chung, Shu-Hsing
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Chou, Kai-Shin
At the end processes of TFT-LCD supply chain, the LCM module factory takes charge of the process of assembling products, and its production planning needs to consider various products with different graded TFT-LCD panels while meeting customers\' specific qualifications, including lowest acceptance rates for quality and zero-bad-defect quantity. Since the machine setup time of the bottleneck workstation in the factory is very long, it is of practical importance to design an appropriate production scheduling with concerns about times of machine setups and different grades of TFT-LCD products. This paper proposes a production scheduling system that comprises the material planning with downgraded products as well as the bottleneck scheduling for a LCM module factory using make-to-stock production, and solves the system based on integer programming. Experimental results show that the system not only is capable of reducing the number of setup times, but also performs well in efficiency of preparing critical materials. From a practical aspect, such a system can support production managers to plan their production scheduling effectively.
Modeling the Material Allocation System for TFT-LCD Module Factories Based on Make-to-Stock Production
(2014-12-01)
Lin, Chun-Cheng
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Kang, Jia-Rong
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Chung, Shu-Hsing
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工業工程與管理學系
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Department of Industrial Engineering and Management
The thin flim transistor liquid crystal display (TFT-LCD) module factories are in charge of the last process of the TFT-LCD supply chain, i.e., assembling LCD panels (produced from the former process in the supply chain) as well as electronic components into TFT-LCD panels or the finished products using TFT-LCD panels. Since the variation of machine processes and production techniques at the former process of the supply chain results in a variety of qualities of LCD panels, the finished products assembled with those LCD panels of different qualities are also of different qualities, according to which they are classified into different grades. This paper models the material allocation system for a TFT-LCD module factory based on the make-to-stock (MTS) production, in which one of the main designs is to allow the flexibility that the finished products of higher grades are able to be downgraded to respond to the drastic variation of customer requirements for each grade of finished products. The system is modelled in detail by an integer programming approach that takes into account not only downgraded products but also the customer requirements for the quality qualification rate and the lower bound of non-dot-defect rate of products, to maximize the total profit of the product portfolio. The model is evaluated by conducting an experimental study for a numerical example, which turns out that the proposed system looks promising as it determines a feasible product portfolio that decreases both the inventory of LCD panels and the volume of unqualified products while maintaining a high profit.
To estimate the stage completion time for a two-stage flexible flow shop with dynamic job arrival
(2008)
Yang, Ming-Hsien
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Chung, Shu-Hsing
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Ka, Ching-Kuei
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工業工程與管理學系
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Department of Industrial Engineering and Management
Considering the two-stage flexible flow shop with dynamic job arrival, each stage contains identical parallel machines, and the second stage receives jobs with stochastic arriving time from first stage. To estimate the job completion time at each stage is useful to enhance the customer service or production performances. The completion time of jobs at each stage can be determined with the sum of the stage arriving time, the expected stage waiting time, and the expected stage service time of jobs. The expected stage waiting time of job relates to the utilization rates of machines, which should be corrected due to the idleness of machine. The idle time depends on the number of jobs in the system at specific time. The birth-and-death process can be used to describe probabilistically how the number of jobs in the system changes as time increasing. Note the stage service time of jobs relates to the estimated setup time and the processing time of jobs at each stage. To analyze the accuracy on the estimated stage completion time of jobs, a computational test through simulation is conducted to verify the proposed probabilistic model.