Browsing by Author "Li, Rong-Kwei"

Now showing 1 - 13 of 13

A study of developing an input-oriented ratio-based comparative efficiency model
(2011-03-01)
Wei, Ching-Kuo
;
Chen, Liang-Chih
;
Li, Rong-Kwei
;
Tsai, Chih-Hung
;
工業工程與管理學系
Data envelopment analysis (DEA) is a representative method to estimate efficient frontiers and derive efficiency. However, in a situation with weight restrictions on individual input-output pairs, its suitability has been questioned. Therefore, the main purpose of this paper is to develop a mathematical method, which we call the input-oriented ratio-based comparative efficiency model, DEA-R-I, to derive the input-target improvement strategy in situations with weight restrictions. Also, we prove that the efficiency score of DEA-R-I is greater than that of CCR-I, which is the first and most popular model of DEA, in input-oriented situations without weight restrictions to claim the DEA-R-I can replace the CCR model in these situations. We also show an example to illustrate the necessity of developing the new model. In a nutshell, we developed DEA-R-I to replace CCR-I in all input-oriented situations because it sets a more accurate weight restriction and yields a more achievable strategy. (C) 2010 Elsevier Ltd. All rights reserved.
A study of optimal weights of Data Envelopment Analysis - Development of a context-dependent DEA-R model
(2012-03-01)
Wei, Ching-Kuo
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Chen, Liang-Chih
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Li, Rong-Kwei
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Tsai, Chih-Hung
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Huang, Hsiao-Ling
The weight is one of the main issues of Data Envelopment Analysis (DEA), and relevant theoretical research indicates that many DEA mathematical models include redundant restraints on weight, resulting in underestimated efficiency, pseudo inefficiency, and difficulty in representing specific Input/Output relationships. This study proposes a context-dependent DEA-R model to address shortcomings resulting from redundant restraints on the weights of an efficient decision making unit (DMU), and converts the optimal weight to analyze the influences of redundant restraints on weights. The evaluation results of Taiwan medical centers show that the efficiency of the DMU is underestimated and pseudo inefficiency may occur due to redundant restraints on weight. Moreover, optimal weights are used as variables to conduct cluster analysis in order to determine the information of the weights. The results of cluster analysis indicate that it can assist DMUs in understanding the relationships between DMUs, and contribute to the development of a unique survival strategy for hospitals. (C) 2011 Elsevier Ltd. All rights reserved.
A Systematic Evaluation Model for Solar Cell Technologies
(2014)
Hsu, Chang-Fu
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Li, Rong-Kwei
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Kang, He-Yau
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Lee, Amy H. I.
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工業工程與管理學系
Fossil fuels, including coal, petroleum, natural gas, and nuclear energy, are the primary electricity sources currently. However, with depletion of fossil fuels, global warming, nuclear crisis, and increasing environmental consciousness, the demand for renewable energy resources has skyrocketed. Solar energy is one of the most popular renewable energy resources for meeting global energy demands. Even though there are abundant studies on various solar technology developments, there is a lack of studies on solar technology evaluation and selection. Therefore, this research develops a model using interpretive structural modeling (ISM), benefits, opportunities, costs, and risks concept (BOCR), and fuzzy analytic network process (FANP) to aggregate experts' opinions in evaluating current available solar cell technology. A case study in a photovoltaics (PV) firm is used to examine the practicality of the proposed model in selecting the most suitable technology for the firm in manufacturing new products.
An Integrated Purchase and Production Model for Solar Manufacturing
(2013)
Li, Rong-Kwei
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Hsu, Chang-Fu
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Kang, He-Yau
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Lee, Amy H. I.
;
工業工程與管理學系
How to improve competitive edges to meet rapidly changing technological innovations and dynamic customer needs is crucial for the survival and success of firms under a global competitive market. Many firms realize that a good supply chain management is a necessity in the intensive competitive international market. In consequence, it is important for a firm to provide products with a lower cost and good quality at the right time and place to maintain a competitive edge. In this paper, a joint replenishment model for multiple suppliers is developed using a mixed integer programming (MIP) to determine the optimal replenishment time and quantity. The model aims to solve the shortcomings of existing joint replenishment models and to increase the performance and customer satisfaction of the replenishment system. The proposed model is applied in a solar cell manufacturer to maintain a good integrated purchase and production plan.
Bottleneck-based heuristic dispatching rule for optimizing mixed TDD/IDD performance in various factories
(2008-03-01)
Ho, Tseng-Fung
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Li, Rong-Kwei
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工業工程與管理學系
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Department of Industrial Engineering and Management
Most research on scheduling problems focuses on increasing production efficiency. For instance, the shortest processing time (SPT) and earliest due date (EDD) dispatching rules perform well in minimizing mean flow time and reducing maximum tardiness, respectively. However, those indices ignore the financial impact (material cost and order price) on the factory. Previous studies focused mainly on cycle time and due date. However, the theory of constraint (TOC) considers not only the effect of time, but also financial factors. Therefore, TOC addresses the concepts of throughput-dollar-day (TDD) and inventory-dollar-day (IDD). The former index (TDD) represents penalties for tardy deliveries, while the latter index (IDD) refers to the material holding cost. Based on these two indices, this investigation creates a novel mixed TDD/IDD weighted value (Z(value)) to replace the other traditional indices for taking measurements in various factories. This study also designs a heuristic dynamic scheduling algorithm (mixed TDD/IDD dispatching rule) for reducing the system Z(value). Some traditional dispatching rules are compared with the proposed rule in terms of TDD, IDD, and Z(value). Analytical results indicate that the mixed TDD/IDD dispatching rule is feasible and generally outperforms other conventional dispatching rules in terms of Z(value) under various factories.
Coordination of production scheduling and delivery problems with heterogeneous fleet
(2014-07-01)
Low, Chinyao
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Chang, Chien-Min
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Li, Rong-Kwei
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Huang, Chia-Ling
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工業工程與管理學系
In a production scheduling with delivery problem, there are different types of products processed by a distribution center and then delivered to retailers. Each retailer order might be consisted of different products. The resolution of this problem is to determine the production sequence, retailers\' needs to heterogeneous fleet of vehicles and the visiting sequence of each vehicle for delivery goods within time windows. In this article, a nonlinear mathematical model is proposed with minimizing the total cost which includes transportation cost, vehicle arrangement cost and penalty costs, subjected to satisfy all demands of each retailer. Following, two adaptive genetic algorithms (AGAs) are designed and tested in variety of production and delivery scenarios. The computational experiments show that the total cost gradually decreases as the vehicle type employed in the delivery stage increasing. In addition, more kinds of vehicle types provided in the delivery stage could reduce fixed vehicle cost and variable routing cost. (C) 2014 Elsevier B.V. All rights reserved.
D Minimizing Total Earliness and Tardiness for Common Due Date Single-Machine Scheduling with an Unavailability Interval
(2016-01-01)
Low, Chinyao
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Li, Rong-Kwei
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Wu, Guan-He
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper addresses the problem of scheduling.. independent jobs on a single machine with a fixed unavailability interval, where the aim is to minimize the total earliness and tardiness (TET) about a common due date. Two exact methods are proposed for solving the problem: mixed integer linear programming formulations and a dynamic programming based method. These methods are coded and tested intensively on a large data set and the results are analytically compared. Computational experiments show that the dynamic programming method is efficient in obtaining the optimal solutions and no problems due to memory requirement.
Exploration of efficiency underestimation of CCR model: Based on medical sectors with DEA-R model
(2011-04-01)
Wei, Ching-Kuo
;
Chen, Liang-Chih
;
Li, Rong-Kwei
;
Tsai, Chih-Hung
;
工業工程與管理學系
Data Envelopment Analysis (DEA) is one of the best-known efficiency evaluation methods due to its advantages in selection of weights. Many research papers have extensively discussed the issue of weight restrictions, rather than those implied in the model itself. However, this often leads to a failure to represent the relations of certain weights, as well as underestimation of the efficiency of Decision Making Units (DMUs). When analyzing the medical sectors of Taiwan with the developed models and CCR, it is found that efficiency underestimation by efficient DMUs is more serious than that of inefficient DMUs. In addition, underestimation occurs when weights are concentrated in the same output, however, every output of referenced DMU is the same times of corresponding output of targeted DMU. (C) 2010 Elsevier Ltd. All rights reserved.
Integrated scheduling of production and delivery with time windows
(2013-02-01)
Low, Chinyao
;
Li, Rong-Kwei
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Chang, Chien-Min
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper deals with an integrated scheduling problem in which orders have been processed by a distribution centre and then delivered to retailers within time windows. We propose a nonlinear mathematical model to minimise the time required to complete producing the product, delivering it to retailers and returning to the distribution centre. The optimal schedule and vehicle routes can be determined simultaneously in the model. In addition, two kinds of genetic-algorithm-based heuristics are designed to solve the large-scale problems. The conventional genetic algorithm provides the search with a high transition probability in the beginning of the search and with a low probability toward the end of the search. The adaptive genetic algorithm provides an adaptive operation rate control scheme that changes rate based on the fitness of the parents. The experimental results have shown that the solution quality of these two algorithms is not significant but that the adaptive genetic algorithm can save more time in finding the best parameter values of the genetic algorithm.
Minimizing Total Earliness and Tardiness for Common Due Date Single-Machine Scheduling with an Unavailability Interval
(2016-01-01)
Low, Chinyao
;
Li, Rong-Kwei
;
Wu, Guan-He
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper addresses the problem of scheduling.. independent jobs on a single machine with a fixed unavailability interval, where the aim is to minimize the total earliness and tardiness (TET) about a common due date. Two exact methods are proposed for solving the problem: mixed integer linear programming formulations and a dynamic programming based method. These methods are coded and tested intensively on a large data set and the results are analytically compared. Computational experiments show that the dynamic programming method is efficient in obtaining the optimal solutions and no problems due to memory requirement.
Research on enhancement of TOC Simplified Drum-Buffer-Rope system using novel generic procedures
(2010-05-01)
Lee, Jun-Huei
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Chang, Jia-Ging
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Tsai, Chih-Hung
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Li, Rong-Kwei
;
工業工程與管理學系
The Theory of Constraints (TOC) Simplified Drum-Buffer-Rope (SDBR) system works effectively in typical job shop environments. However, according to the experiences implementing SDBR system in local companies, such environments have the following characteristics, which may block SDBR implementation: (1) capacity constraint resources (CCR) is not always located in the middle of the routing as assumed in SDBR. The CCR can be located in either the front or back end of routing; (2) multiple or interactive CCRs can exist rather than the assumption of just one CCR; (3) order insertion, including urgent orders, change in due-date (especially bringing it forward) is common. Two ways may be applied to overcome these characteristics: (1) move back to a traditional DBR; (2) address problems through the buffer management process. However, both these ways have limitations and complexities. This paper presents an alternative method enhancing SDBR system performance. With the enhancement, we expect that SDBR can be adopted by more companies, especially those that have the same characteristics. (C) 2009 Elsevier Ltd. All rights reserved.
USING GAME AND STATISTICAL ANALYSIS TO CONFIRM GOLDRATT'S LOGICAL ANALYSIS OF POOR DELIVERY IN A MULTI-PROJECT ENVIRONMENT
(2011-11-01)
Huang, Chia-Ling
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Chang, Hao-Ging
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Li, Rong-Kwei
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Tsai, Chih-Hung
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工業工程與管理學系
The objective of this study is to confirm Goldratt's logical analysis of poor delivery in a multi-project environment. Two hundred and ten experienced managers were invited to participate in a multi-project management game that simulates reality. A statistical analysis of the experimental data of this study indicates that the mode of project planning and execution (unrealistic project planning, a lack of clear working priorities, misuse of safety time, and bad multi-tasking), not uncertainty, is the root cause of poor delivery, and should therefore be improved first. The result confirmed Goldratt's logical analysis of poor delivery in project management.
Using the DEA-R model in the hospital industry to study the pseudo-inefficiency problem
(2011-03-01)
Wei, Ching-Kuo
;
Chen, Liang-Chih
;
Li, Rong-Kwei
;
Tsai, Chih-Hung
;
工業工程與管理學系
Because of the unreasonable and unnecessary weight restriction assumption, a barely noticeable deficiency in pseudo-inefficiency occurs at times when applying a CCR model. The CCR was the first model designed for Data Envelopment Analysis (DEA); it remains its most popular model. To detect this type of unobvious deficiency, this study compared the following; the efficiency score and optimal weight set of an input oriented CCR model (CCR-I); the model with a weight restriction assumption; an input-oriented ratio-based DEA model (DEA-R-I); and the model without it. In this case study of hospitals, pseudo-inefficiency was discovered and the reason behind it determined. Further, this study proved that the DEA-R-I is a valid model. Because DEA-R-I is valid and without a weight restriction assumption, this study puts forward the DEA-R-I as a capable substitutive model for CCR-I in order to avoid pseudo-inefficiency. (C) 2010 Elsevier Ltd. All rights reserved.