Browsing by Author "Li, RK"

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A due-date oriented scheduling heuristic for job shop cellular manufacturing system
(2000-03-01)
Tsai, CH
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Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Although having gained further insight into scheduling problems involving cellular manufacturing systems, previous research has neglected two characteristics that are essential for effective group scheduling: first, due-date performance focus; second, setup time savings by emphasizing constrained and non-constrained machines. To overcome these two characteristics, we present a due-date oriented scheduling heuristic algorithm for jab shop cellular manufacturing system based on Capacity Constraint Resource (CCR). The proposed algorithm consists of four stages: (1) schedule development for CCR (DRUM), (2) CCR setup time savings to decrease mean tardiness, (3) CCR setup time savings to maximize CCR throughput, and (4) development of a hybrid scheduling method to minimize total flowtime and the work-in-process (WIP) inventory. Also, an illustrative example demonstrates the feasibility of the proposed method. Significance: This study has developed a due-date oriented scheduling heuristic algorithm for job shop cellular manufacturing environments. The proposed algorithm's strong performance indicates that our four-stage group scheduling heuristic, with its more sensitive switching procedures, can not only overcome some of the weaknesses shown by exhaustive and non-exhaustive scheduling heuristics, but can also glean setup time savings without sacrificing due-date performance.
A methodology for schedule compression
(1996-07-01)
Wu, HH
;
Li, RK
;
交大名義發表
;
工業工程與管理學系
;
National Chiao Tung University
A generated schedule can be improved (especially on due date performance) simply by compressing the current schedule to the left. Additionally, two forms of schedule compression are available, i.e. simple compression and complex compression. In practical considerations, however, knowing exactly where the compression effort should be placed so that the schedule can be improved more efficiently is a relatively difficult task. This decision requires an evaluation methodology, which is the primary objective of this study. The evaluation methodology is based on the priority weight computation for those affected operations. The priority weight computation is an integration of sequence effect weight with time effect weight. The priority weight information provides not only where the compression effort should be placed but also the intelligent information of (1) the operations related to the compression effort and (2) the time that job(s) can be packed to the left. Specifics of the schedule compression concepts and algorithms of the evaluation methodology are also discussed.
A methodology for schedule compression
(1996-07-01)
Wu, HH
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
A generated schedule can be improved (especially on due date performance) simply by compressing the current schedule to the left. Additionally, two forms of schedule compression are available, i.e. simple compression and complex compression. In practical considerations, however, knowing exactly where the compression effort should be placed so that the schedule can be improved more efficiently is a relatively difficult task. This decision requires an evaluation methodology, which is the primary objective of this study. The evaluation methodology is based on the priority weight computation for those affected operations. The priority weight computation is an integration of sequence effect weight with time effect weight. The priority weight information provides not only where the compression effort should be placed but also the intelligent information of (1) the operations related to the compression effort and (2) the time that job(s) can be packed to the left. Specifics of the schedule compression concepts and algorithms of the evaluation methodology are also discussed.
A new ART-counterpropagation neural network for solving a forecasting problem
(2005-01-01)
Liu, TC
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study presents a novel Adaptive resonance theory-Counterpropagation neural network (ART-CPN) for solving forecasting problems. The network is based on the ART concept and the CPN learning algorithm for constructing the neural network. The vigilance parameter is used to automatically generate the nodes of the cluster layer for the CPN learning process. This process improves the initial weight problem and the adaptive nodes of the cluster layer (Kohonen layer). ART-CPN involves real-time learning and is capable of developing a more stable and plastic prediction model of input patterns by self-organization. The advantages of ART-CPN include the ability to cluster, learn and construct the network model for forecasting problems. The network was applied to solve the real forecasting problems. The learning algorithm revealed better learning efficiency and good prediction performance. (C) 2004 Elsevier Ltd. All rights reserved.
Capability evaluation of a product family for processes of the larger-the-better type
(2002)
Chen, KS
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Li, RK
;
Liao, SJ
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Process capability indices (PCIs) have been widely used in manufacturing industry, but most of the studies associated with analysing the quality and efficiency of a process are limited to discussing one single quality specification. Practically, a product family is usually composed of several models, which result in different specifications. Generally, the quality characteristics of a product can be classified into three types; the nominal-the-best, the smaller-the-better and the larger-the better types. This paper introduces one simple and applicable method to evaluate the process capability of a product family. The process is of the larger-the-better type and consists of several models with different specifications. For practical applications, a simple step-by-step procedure is established to determine whether the total process capability of the product family meets the preset target. Finally, an example is given and a procedure for a hypothesis test is provided for easy application.
Constraint time buffer determination model
(1998-04-01)
Tu, YM
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Li, RK
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工業工程與管理學系
;
Department of Industrial Engineering and Management
In today's competitive environment, reducing Work in Process (WIP) to improve cycle time, delivery and product quality has become the key to maintaining profitability. However, due to conservative attitudes and conceptual mistakes, WIP has spread along the entire production pipe line. Although intended to maximize the utilization of resources, WIP can be caused to become over-sized. This maximum utilization of resources syndrome has been proved incorrect by the Theory of Constraint and WIP should be queued only in front of constraint machine, thereby ensuring the constraint machine not starvation. Although this concept has been proved correct and despite many reported examples of successful implementation in many companies, in practice, the WIP level is still determined by the trial and error approach. Therefore, a WIP computation model is deemed necessary. In this paper, a constraint time buffer determination model is proposed. The model first proposes a machine-view's bill of routing representing a structure that serves as a fundamental structure for formulating and computing the maximum time buffer. The machine-view's bill of routing is a tree structure, the constraint machine is the root node and its feeder machines are entry nodes (or subtrees) of the root node. With this tree structure, the behaviour (or stability) of the constraint machine and its feeder machines can then be studied and formulated. By incorporating the MTTR of each feeder machine, a mathematical relationship can then be formulated and the time buffer computed. Furthermore, to validate the proposed constraint time buffer determination model, an example is illustrated and a simulation model is also developed.
Contract manufacturer selection by using the process incapability index C-pp
(2005-09-01)
Chen, KS
;
Chen, KL
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
In the competitive global business environment, enterprises should effectively respond to and satisfy customer needs. Outsourcing manufacturing is an effective method of adjusting the flexibility of production capability. To ensure final product quality, evaluating and selecting a contract manufacturer is essential. Process capability indices are extensively adopted in manufacturing to determine whether a process meets capability requirements. This study attempts to determine the score index R-i and then apply it to assess the process performance of contract manufacturer by using the process incapability index C-pp. The formulae for C-pp and R-i are simple to understand and to apply. The procedure developed in this paper is also an easy and convenient tool for practitioners to assess contract manufacturer quality performance and make more reliable decisions regarding contract manufacturer.
Design of a rule-based continuous process controller using modified IDEF0 methodology
(1997-09-01)
Chen, SG
;
Wu, MZ
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Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This article proposes a new method to design a rule-based Continuous Process (CP) controller. This approach adopts Modified IDEF0 (MI) diagrams as a graphical representation of production rules. Initially, the material flows or functional requirements for the CP are specified by synthesizing the MI diagram primitives. The control flows for the CP are then created by a number of transformation rules. The MI diagrams are therefore transformed to the Final MI (FMI) diagrams which can be directly transformed to production rules. The fact that production rules are created by systematical transformation eliminates any redundant, contradictory, or unnecessary rules. The simulation approach can verify the consistency of the designed CP controller. Thus, a feasible rule-based CP controller can be systematically developed. An illustrative gas transmission system is examined with three manufacturing policies, i.e. Proportional plus Integral plus Derivative (PID) control, Neural control and Fuzzy control. The results indicate that all of these policies are feasible in applying the proposed method. This method not only provides graphical representations to construct well-organized production rules, but also includes a systematical transformation of the control flows for a CP controller.
Design of a rule-based continuous process controller using modified IDEF0 methodology
(1997-09-01)
Chen, SG
;
Wu, MZ
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This article proposes a new method to design a rule-based Continuous Process (CP) controller. This approach adopts Modified IDEF0 (MI) diagrams as a graphical representation of production rules. Initially, the material flows or functional requirements for the CP are specified by synthesizing the MI diagram primitives. The control flows for the CP are then created by a number of transformation rules. The MI diagrams are therefore transformed to the Final MI (FMI) diagrams which can be directly transformed to production rules. The fact that production rules are created by systematical transformation eliminates any redundant, contradictory, or unnecessary rules. The simulation approach can verify the consistency of the designed CP controller. Thus, a feasible rule-based CP controller can be systematically developed. An illustrative gas transmission system is examined with three manufacturing policies, i.e. Proportional plus Integral plus Derivative (PID) control, Neural control and Fuzzy control. The results indicate that all of these policies are feasible in applying the proposed method. This method not only provides graphical representations to construct well-organized production rules, but also includes a systematical transformation of the control flows for a CP controller.
Design of a rule-based flexible manufacturing system controller using modified IDEF0 methodology
(1997-10-01)
Chen, SG
;
Wu, MZ
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Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This article proposes a new method to design a rule-based FMS controller. This approach adopts modified IDEFO (MI) diagrams as a graphical representation of the production rules. Initially, the material flows or functional requirements for the FMS are specified by synthesizing the MI diagram primitives. The control flows for the FMS are then created by a number of transformation rules. The manufacturing policy, e.g. deadlock avoidance policy, is also specified and attached. The MI diagrams are therefore transformed to the final MI (FMI) diagrams which can be directly transformed to the production rules. Thus, a concise rule-based FMS controller is developed. The fact that the production rules are created by systematic transformation eliminates any redundant, contradictory, or unnecessary rules. Two approaches can verify the consistency of the designed FMS controller. The controlled Petri net approach can be adopted for verifying a small system, while a simulation approach is preferable for verifying a large system. By iterating the process, a feasible rule-based FMS controller can be systematically developed. This method not only provides graphical representations to construct well-organized production rules, but also includes a systematic transformation of the control flows for an FMS controller.
Development of an artificial neural network to predict lead frame dimensions in an etching process
(2006-02-01)
Liu, TC
;
Li, RK
;
Chen, MC
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工業工程與管理學系
;
Department of Industrial Engineering and Management
The electronic industry is rapidly developing, creating high demand for IC production. Etched semiconductor lead frames are the basic material used in IC packaging. IC packaging requires high-precision lead frames. The dimensions of the pilot hole are generally required to be highly precise in lead frame manufacturing. The photo-etching process must control the dimension of the pilot hole and record the manufacturing data of the etching machine and inspection data. This study presents the development of an artificial neural network (ANN) model that can be applied to construct the predicting model. The predictive model can estimate the dimensions of the pilot hole and thus determine the process parameters needed to improve lead frame quality in the etching process.
Enhancement of Theory of Constraints replenishment using a novel generic buffer management procedure
(2003)
Yuan, KJ
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Chang, SH
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Li, RK
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工業工程與管理學系
;
Department of Industrial Engineering and Management
Managing a distribution system requires the right inventory in the right place at the right time. A Theory of Constraints replenishment solution is presented to aggregate inventory buffers at the central warehouse in plant and change the mode of operation from push to pull. The solution is powerful, but the optimal amount of buffer remains undetermined. In Theory of Constraints, choosing a specific buffer size is not crucial if the buffer is accurately monitored in a timely manner. Accordingly, Theory of Constraints is offered a buffer management approach for monitoring the buffer. Such buffer management is feasible and effective but is insufficiently rigorous. This paper elucidates a generic buffer management procedure, based on the concept of Theory of Constraints buffer management that rigorously defines a method of monitoring to size and adjust the buffer. An example demonstrates the feasibility of the proposed generic buffer management procedure.
Exact solution of inventory replenishment policy for a linear trend in demand - two-equation model
(2002-03-21)
Lo, WY
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Tsai, CH
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Li, RK
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工業工程與管理學系
;
Department of Industrial Engineering and Management
This study presents a model for obtaining the exact optimal solution of inventory replenishment policy problem. The proposed model, called the "two-equation model", includes two governing equations and a time-frequency algorithm: the first equation determines the optimal replenishment times for a specified number of replenishments; the second equation determines the optimal number of replenishments. The time-frequency algorithm includes two main procedures to solve the first and second equations. In contrast to many approximation approaches, this model exactly solves the first equation, a simultaneous non-linear equations system using a generalized matrix-based solver. This study also examines the classical no-shortage inventory replenishment policy for linear increasing and decreasing trend demand. According to these results, the solution given by the two-equation model is an exact solution. (C) 2002 Elsevier Science B.V. All rights reserved.
Graphical analysis of capability of a process producing a product family
(2005-10-01)
Huang, ML
;
Chen, KS
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Statistical techniques are effective and powerful means of quantifying the variability of processes, analyzing this variability with reference to product requirements, and eliminating this variability in product manufacturing. Many process capability indices have been effectively and widely used to determine whether the quality of a process meets preset targets. However, conventional process capability indices cannot be applied to assess the entire process capability of a product family with nominal-the-best specifications. This work presents a novel process capability index (C-pp(T)), which takes into account all family members. The index C-pp is a simple transformation from index C-pm, and C-pp(T) provides additional, individual information concerning the accuracy and precision of a process. Vannman's (delta, gamma)-plot [Vannman and Deleryd, Quality and Reliability Engineering International 15(3): 213-217 (1999)] is revised to compare the process capabilities of family members under both 100% inspection and sampling plans. Examples are provided to demonstrate the method's practical application.
Heuristic dispatching rule to maximize TDD and IDD performance
(2004-12-15)
Ho, TF
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Li, RK
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工業工程與管理學系
;
Department of Industrial Engineering and Management
Although mean flow time and tardiness have been used for a long time as indicators in both manufacturing plants and academic research on dispatching rules, according to Theory of Constraints (TOC), neither indicator properly measures deviation from production plans. TOC claims that using throughput dollar-day (TDD) and inventory dollar-day (IDD) can induce the factory to take appropriate actions for the organization as a whole, and that these can be applied to replace various key performance indices used by most factories. However, no one has studied dispatching rules based on TDD and IDD performance indicators. The study addresses two interesting issues. (1) If TDD and IDD are used as performance indicators, do those dispatching rules that yield a better performance in tardiness and mean flow time still yield satisfactory results in terms of TDD and IDD performance? (2) Does a dispatching rule exist to outperform the current dispatching rules in terms of TDD and IDD performance? First, a TDD/IDD-based heuristic dispatching rule is developed to answer these questions. Second, a computational experiment is performed, involving six simulation examples, to compare the proposed TDD/IDD-based heuristic-dispatching rule with the currently used dispatching rules. Five dispatching rules, shortest processing time, earliest due date, total profit, minimum slack and apparent tardiness cost, are adopted herein. The results demonstrate that the developed TDD/IDD-based heuristic dispatching rule is feasible and outperforms the selected dispatching rules in terms of TDD and IDD.
Heuristic PAC model for hybrid MTO and MTS production environment
(2003-09-11)
Chang, SH
;
Pai, PF
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Yuan, KJ
;
Wang, BC
;
Li, RK
Two distinct types of semiconductor plants in Taiwan are integrated device manufacturing (IDM) plants and foundry plants. Most IDM plants are make-to-stock (MTS) operations, focusing on throughput and machine utilization. However, foundry plants are make-to-order (MTO) operations, focusing on due date and cycle time. Besides the challenge of different process technology, the mode of hybrid operation (a combination of MTO and MTS operations) is also a formidable task for these plants. This study develops a heuristic production activity control model to achieve the two different criteria in a hybrid wafer production environment. (C) 2003 Elsevier B.V. All rights reserved.
Integrating order release control with due-date assignment rules
(1997-12-01)
Tsai, CH
;
Chang, GT
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Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study integrates order release control methods with due-date assignment rules and assesses its impact on the accuracy of inter-operation time estimation and performance of due-date assignment. The assessment is made by using an experimental design with three due-date assignment rules, three scheduling rules and three order release models. The three order release models are: (1) Basic model, in which three due-date assignment rules consider the order arrival time as the order release time; (2) Control model, in which three due-date assignment rules integrate with the order release control method developed here; and (3) Adjustment model, in which the control model integrates with the order release control adjustment developed here. Simulation results in this study indicate that integrating the order release control method with due-date assignment rules will significantly enhance not only the accuracy of interoperation time estimation, but also the performance of due-date assignment rules.
Integrating order release control with due-date assignment rules
(1997-12-01)
Tsai, CH
;
Chang, GT
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study integrates order release control methods with due-date assignment rules and assesses its impact on the accuracy of inter-operation time estimation and performance of due-date assignment. The assessment is made by using an experimental design with three due-date assignment rules, three scheduling rules and three order release models. The three order release models are: (1) Basic model, in which three due-date assignment rules consider the order arrival time as the order release time; (2) Control model, in which three due-date assignment rules integrate with the order release control method developed here; and (3) Adjustment model, in which the control model integrates with the order release control adjustment developed here. Simulation results in this study indicate that integrating the order release control method with due-date assignment rules will significantly enhance not only the accuracy of interoperation time estimation, but also the performance of due-date assignment rules.
Mixing macro and micro flowtime estimation model: wafer fab example
(1999-07-20)
Tseng, TY
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Ho, TF
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Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Accurately predicting the order flowtime for a wafer fab is a critical task. Previous investigations involving flowtime estimation of the regression approach have extensively applied the macro flowtime estimation concept. The 'macro' flowtime estimation concept constructs only one aggregate model to estimate the flowtime as a whole. In contrast, the 'micro' flowtime estimation approach constructs an individual regression model for each stage of operation to estimate its individual flowtime. The cumulative order estimated flowtime is then the sum of the individual estimated operation flowtime. Each approach has its own merits and limitations. Therefore, in this study we examine the feasibility of mixing the macro and micro flowtime estimation models. Comparing the proposed model with a variety of macro and micro models reveals that the mixed macro and micro flowtime estimation model can achieve a balance between flowtime estimation error and model complexity.
Process capability analysis for an entire product
(2001-11-01)
Chen, KS
;
Huang, ML
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Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Process capability indices (PCIs) are powerful means of studying the process ability for manufacturing a product that meets specifications. Several capability indices including C-p, C-pu, C-pl and C-pk have been widely used in manufacturing industry to provide common quantitative measures on process potential and performance. The formulas for these indices are easily understood and can be straightforwardly applied. However, those process capability indices are inappropriate for asymmetric tolerances and could not be applied to evaluate multiprocess products. Based on C-p, C-pu, C-pl and C-pk, this research aims to develop one process capability analysis chart (PCAC) for precisely measuring an entire product composed of symmetric tolerances, asymmetric tolerances, larger-the-better and smaller-the-better characteristics. The process capability analysis chart evaluates the capabilities of multi-process products and provides chances for continuous improvement on the manufacturing process.