Browsing by Author "Lee, Ming-Tsung"

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APPLICATION OF IMPORTANCE-SATISFACTION ANALYSIS AND INFLUENCE-RELATIONS MAP TO EVALUATE DESIGN DELAY FACTORS
(2014-08-01)
Wang, Wei-Chih
;
Lin, Chia-Li
;
Wang, Shih-Hsu
;
Liu, Jang-Jeng
;
Lee, Ming-Tsung
Design delays can negatively influence the total completion time of a facility construction project. Knowing the factors to which design delays are most sensitive supports the time management of designs. However, factors that cause design delays are several and interrelated. This study proposes a new model to identify key factors that drive design delays. The core of the model integrates importance-satisfaction analysis (ISA) and an influence-relations map (IRM). The ISA evaluates the performance of each delay factor, while the IRM captures the causal relationships among factors. Additionally, the IRM is generated using a decision making trial and evaluation laboratory technique (DEMATEL). The model is applied to a real-world high-tech facility construction project to indicate the strengths of the model. In this investigation, four first-level delay factors and 17 second-level delay sub-factors are derived. The factor of "organization\'s decision making and budget constraints" is identified as the key driver of design delays in the project of interest. The results support management in determining which problem factors should be given priority attention. The proposed model can be employed in other decision-making situations that involve interrelated factors.
APPLYING THE AHP TO SUPPORT THE BEST-VALUE CONTRACTOR SELECTION - LESSONS LEARNED FROM TWO CASE STUDIES IN TAIWAN
(2013)
Wang, Wei-Chih
;
Yu, Wen-der
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Yang, I-Tung
;
Lin, Chun-Chang
;
Lee, Ming-Tsung
Lately the Best-Value (BV) method for contractor selection has been receiving considerable attention in the public sector in many countries. However, the operations used in performing the BV method often differ due to the various government procurement requirements. Consequently, some of the methods popular in the academic community are not easily incorporated in the BV method in some countries. To enhance the procurement process, this study aims to gain experience by applying the well-known analytical hierarchy process (AHP) to weight the decision criteria for selecting BV contractors of two construction projects in Taiwan. Through these two case studies, this work confirms that the AHP provides a significant benefit for considering the individual preferences of all decision-makers when weighting the criteria. However, this study finds two major potential obstacles, the legal requirements associated with using the AHP and the time it takes to implement the AHP. To overcome these obstacles, this work suggests guidelines to meet the legal requirements for implementing the AHP in the BV contractor selection, and proposes several strategies to shorten the AHP implementation time. The lessons learned here are relevant to those countries in which BV method must be performed in a transparent and strictly regulated environment.
Canonical Ensemble Statistics of Weakly Interacting Composite Boson Condensation: Thermodynamic Properties
(2013-10-01)
Lee, Ming-Tsung
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光電工程學系
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Department of Photonics
We present a canonical ensemble approach for weakly interacting composite boson systems, which is confined with a finite number of particles. Composite bosons, made of fermion pairs, correlate to each other through the Coulomb interaction associated with the fermion exchange, and are treated perturbatively. We study Bose-Einstein condensation of composite bosons according to the specific heat capacity, the composite-boson distribution function, and the condensate fraction up to the first-order perturbations. As an example, we investigate two-dimensional confined excitons. The study shows that the fermion exchange tends to assist the exciton condensation by raising the temperature. This stabilization of the exciton condensation owing to the fermion exchange is characterized by a small trough in the specific heat capacity profile. As the temperature becomes higher than the transition temperature, the effective Coulomb interaction reduces the thermal fluctuation of excitons, leading to a negative correction to the specific heat capacity in the normal phase. Weakly interacting excitons stay in a more stable thermodynamic state in comparison with ideal exciton gases.
DEMATEL-based model to improve the performance in a matrix organization
(2012-04-01)
Wang, Wei-Chih
;
Lin, Yueh-Hua
;
Lin, Chia-Li
;
Chung, Chu-Hsuan
;
Lee, Ming-Tsung
Carrying out a design project for a high-tech facility requires a large amount of special knowledge in order to deal with the specific requirements from the client. Often the client forms a matrix organization, structured with several interrelated functional and project divisions to dictate the various requirements and needs. However, an ill-defined matrix organization is likely to result in late and inadequate decisions. This in turn may result in a poorly performing design. Identifying those divisions within the organization that perform poorly in the way they provide information for the project is critical. Therefore, this study proposes an innovative model to identify those divisions that may be responsible for the poor performance of the design project. The proposed model integrates the satisfied importance analysis (SIA) and the decision making trial and evaluation laboratory technique (DEMATEL). The SIA evaluates the performance of each division, while the DEMATEL captures the causal relationships among divisions to generate an influence-relations map. The proposed model is applied to a real-world high-tech facility design project in Taiwan to demonstrate the strengths of the model. (C) 2011 Elsevier Ltd. All rights reserved.
Pauli Exchange Correlated Composite-Boson Condensation: A Many-Body Green's Function Approach
(2012-07-01)
Lee, Ming-Tsung
;
光電工程學系
;
Department of Photonics
In this research, we develop a many-body Green's function approach for interacting composite bosons in the Bose-Einstein condensed phase. The resummation scheme dealing with the carrier-carrier exchange between many-body composite bosons in cold condensation is manifested as a diagrammatic technique through the introduction of a set of Dyson equations for composite bosons. We diagrammatically calculate the specific heat capacity of neutral composite bosons, made of mass-imbalanced fermions with opposite charges, up to the first orders of the Pauli exchange and Coulomb interaction. Condensate phenomena due to the effect of the carrier-carrier exchange are discussed. In comparison with the approximation that composite bosons behave like interacting fundamental bosons, our result shows that the energy reduction from the carrier-carrier exchange stabilizes composite-boson condensates.