Hsinchu, Taiwan
Hsinchu, Taiwan

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Chiu D.-Y.,ChungHua University | Pan Y.-C.,ChungHua University
Knowledge-Based Systems | Year: 2014

This work presents a novel automated approach to construct topic knowledge maps with knowledge structures, followed by its application to an internationally renowned journal. Knowledge structures are diagrams showing the important components of knowledge in study. Knowledge maps identify the locations of objects and illustrate the relationship among objects. In our study, the important components derived from knowledge structures are used as objects to be spotted in a topic knowledge map. The purpose of our knowledge structures is to find out the major topics serving as subjects of article collections as well as related methods employed in the published papers. The purpose of topic knowledge maps is to transform high-dimensional objects (topic, paper, and cited frequency) into a 2-dimensional space to help understand complicated relatedness among high-dimensional objects, such as the related degree between an article and a topic. First, we adopt independent chi-square test to examine the independence of topics and apply genetic algorithm to choose topics selection with best fitness value to construct knowledge structures. Additionally, high-dimensional relationships among objects are transformed into a 2-dimensional space using the multi-dimension scaling method. The optimal transformation coordinate matrix is also determined by using a genetic algorithm to preserve the original relations among objects and construct appropriate topic knowledge maps. © 2014 Elsevier B.V. All rights reserved.

Yang J.-B.,Chunghua University | Yang C.-C.,Chunghua University | Kao C.-K.,University of Management and Technology
International Journal of Project Management | Year: 2010

Project delivery method of Build-Operate-Transfer (BOT) increases the commencement probability of public construction works through private investments. Public construction works worldwide that adopt the BOT model as their project delivery method are increasing gradually. Although many BOT projects have been implemented at various stages, some projects encounter major obstacles for advancement. This study attempts to identify the delay causes in various stages of BOT projects. Opinions of BOT participants' replies are solicited using two questionnaire surveys. Those outcomes are analyzed using by traditional statistical methods and structural equation modeling method. Study results reveal that the stage of 'negotiation and signing of concession agreement' is the most essential stage, in which 'improper contract planning,' 'debt problem' and 'uncertainty on political issues and government-finished items' are the most significant delay causes. Identified causes of delay can be used to prevent the postponement of future BOT projects. © 2009 Elsevier Ltd and IPMA.

Yang J.-B.,Chunghua University | Wei P.-R.,Farexp Engineering Consultants Ltd.
Journal of Architectural Engineering | Year: 2010

Problems of delay occur in all phases of construction projects. While most previous studies have focused on finding causes or overcoming delays in the construction phase, few studies have analyzed delay problems in the planning and design phases. The main purpose of this study is to identify and rank delay causes in the planning and design phases. A structured questionnaire was sent to engineers at the A/E companies for public construction projects in Taiwan. Based on 95 valid responses, this study identified the delay causes and analyzed the importance and frequency of delays using the relative importance index. Analytical results reveal that "changes in client's requirement" are the main causes of delays in both planning and design phases. The finding is good justification for many public clients who usually change their requirements during the planning and design phases that really delay construction projects. © 2010 ASCE.

Chen M.-X.,National Taiwan University | Wang F.-J.,ChungHua University
International Journal of Communication Systems | Year: 2010

One of the most important research subjects in session initiation protocol (SIP) is mobility management. Session mobility is a key issue in SIP mobility management. Session mobility is an advanced feature that maintains an ongoing media session from one device to another. In this paper, we consider the issue of session mobility and propose a complete integrated solution, referred to as 'session integration service', to transfer an ongoing media session over multiple devices. To provide flexibility in session mobility, three new agent states are introduced based on the user agent definition. They consist of session manager, session user, and free node. This paper also proposes two split session integration methods for session integration service based on these three agents. The proposed method provides session mobility flexibility and allows the user the ability to transfer, split, and retrieve a session over multiple devices. Moreover, the split session can be integrated in any devices. To ensure session mobility over multiple devices, the session integration service will be implemented through a modification of the open source project 'SIP-communicator'. Copyright © 2010 John Wiley & Sons, Ltd.

Hu C.-A.,National Chiao Tung University | Liu J.-W.,National Taiwan Normal University | Wu C.-J.,National Taiwan Normal University | Yang T.-J.,Chunghua University | Yang S.-L.,National Chiao Tung University
Solid State Communications | Year: 2013

Effects of superconducting thin film on the defect mode in a dielectric photonic crystal heterostructure (PCH) are theoretically investigated. The considered structure is (12)NS(21)N, in which both layers 1 and 2 are dielectrics, layer S is a high-temperature superconducting layer, and N is the stack number. The defect mode is analyzed based on the transmission spectrum calculated by using the transfer matrix method. It is found that, in the normal incidence, the defect mode existing in the host PCH of (12) N(21)N will be blue-shifted as the thickness of layer S increases. In addition, the defect mode is also blue-shifted for both TE and TM modes in the case of oblique incidence. The embedded superconducting thin film plays the role of tuning agent for the defect mode of PCH. As a result, the proposed structure can be designed as a tunable narrowband transmission filter which could be of technical use in the optoelectronic applications. © 2013 Elsevier Ltd.

Hung H.-C.,National Cheng Kung University | Wu C.-J.,National Taiwan Normal University | Yang T.-J.,Chunghua University | Chang S.-J.,National Cheng Kung University
Progress in Electromagnetics Research | Year: 2012

In this work, the enhancement in photonic band gap (PBG) in a dielectric-semiconductor photonic crystal (DS PC) is investigated. We consider two possible schemes that can be used to enhance the PBG in the near-infrared region. The first scheme is to add an ultrathin metal layer into the DS PC such that a structure of ternary metal-dielectric-semiconductor (MDS) PC is formed. The second scheme is to make use of the heterostructured PC. In scheme 1, it is found that the addition of metal layer will significantly move the left band edge to the shorter wavelength position, leading to an enlargement in the PBG. This enlargement can be extended as the thickness of metal film is increased. In addition, a pronounced enhancement in PBG is achieved when the metal with a higher plasma frequency is used. In scheme 2, we find that the PBG can be significantly enlarged compared to scheme 1. In addition, the increase in the band extension is shown to be four times larger than that in scheme 1. The results illustrate that, in order to enhance the PBG, the use of scheme 2 is superior to scheme 1. The enhancement of nearinfrared (NIR) PBG is of technical use in the optical communications.

Hu C.-A.,National Chiao Tung University | Wu C.-J.,National Taiwan Normal University | Yang T.-J.,Chunghua University | Yang S.-L.,National Chiao Tung University
Journal of the Optical Society of America B: Optical Physics | Year: 2013

In this work, a theoretical analysis on the effective plasma frequency (EPF) for a one-dimensional superconductor dielectric photonic crystal is made. First, the EPF is extracted from the first photonic band calculated within the framework of transfer matrix method together with Bloch theorem in a periodic multilayer structure. We investigate the EPF as a function of the filling factor and the permittivity of the dielectric layer, and the operating temperature as well. Then, the EPF is comparatively studied by the analytical expression derived from the effective medium theory. It is found that both results are in fairly good agreement. © 2013 Optical Society of America.

Chen M.-X.,National Dong Hwa University | Tzeng T.-C.,ChungHua University
Computer Standards and Interfaces | Year: 2011

This paper describes the service discovery and interaction for home network devices using heterogeneous standards and protocols. OSGi was proposed to allow several kinds of services coming from different providers to be loaded and run on a gateway. We present a residential gateway based on the OSGi architecture for a smart home network. We combine the SLP SA/DA, the UPnP control point and the SIP UA into the gateway to achieve automated device discovery, registry, and management. Application examples are introduced and the implementation results show that our gateway can provide automatic heterogeneous service or device discovery, registry, and management. © 2010 Elsevier B.V. All rights reserved.

Ellipticalconcrete-filled steel tubular(ECFT) columns are often used as the main supporting columns for high-rise buildings and has become a topic of academic concern. The past research about ECFTmost focused on its ultimate strength and mechanical behavior. The experiment method which is usually expensive and time-consuming. Other research methods include combining experimental data with appropriate theory to design or calculate the structural properties, and these methods tend to have a conservative assessment of the results. Therefore, some researches have been developing finite element model to simulate and analyze the ultimate strength and buckling condition of ECFT and its component behavior. In this paper, finite element analysis is used to explore the mechanical behavior of ECFT during exerting axial compression load. Contact pair settings and friction coefficient settings were compared with different pattern to investigate the accuracy of simulation and the mechanical behavior of ECFT columns. Study found that the ultimate strength for ECFT columns obtained by finite element analysis can achieve good accuracy, and in the meantime the mechanical behavior simulation of ECFT columns with proper finite element settings could be achieved. © (2014) Trans Tech Publications, Switzerland.

Shen Y.,Zhejiang University | Kou C.,Chunghua University | Xie X.,Zhejiang University
Journal of Computational and Theoretical Nanoscience | Year: 2016

Taking steel and CFRP cables as objects, this study proposed the computation of aerodynamic modal damping in flexible stay cables. The decaying vibration responses in the air and non-linear strain energy were calculated for steel and CFRP cable with 460 m span. Comparisons were made of influences of sag and amplitude onto aerodynamic and strain modal damping. Results show that aerodynamic modal damping is proportional to amplitude but has less association with mode shape and sag to span length ratio. Strain modal damping of CFRP cable is similar to that of steel cable, both of which increase as amplitude or sag to span length ratio increases. However aerodynamic modal damping of CFRP cable is greater than that of steel cable. Compared with strain modal damping, the aerodynamic damping takes a smaller proportion of steel cable, but the situation is opposite for CFRP cable. © 2016 American Scientific Publishers All rights reserved.

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