Browsing by Issue Date, starting with "2009-02-01"

Now showing 1 - 20 of 51531

Stimuli-Responsive Controlled Drug Release from Magnetic-Sensitive Silica Nanospheres
(2009-02-01)
Hu, Shang-Hsiu
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Liu, Ting-Yu
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Huang, Hsin-Yang
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Liu, Dean-Mo
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Chen, San-Yuan
A novel method for control burst releasing of drug via a high frequency magnetic field (HFMF) from magnetic-sensitive silica nanospheres was developed. The nanospheres were synthesized by a combination of emulsion and sol-gel process with the particles controlled at about 80 nm in diameter. Under repeated exposures to the high frequency magnetic stimulus, the drug release behaviors showed reproducible slow-to-burst profiles while consecutively applying the magnetic stimulus at 10-min switching time and the release profile restored immediately when the stimulus was removed. By taking this non-contact control-burst method, the magnetic silica nanospheres can be designed to treat the cancer therapy and urgent physiological needs.
Expert diagnostic system for moving-coil loudspeakers using nonlinear modeling
(2009-02-01)
Bai, Mingsian R.
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Huang, Chau-Min
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機械工程學系
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Department of Mechanical Engineering
This work aims at the development of an expert diagnostic system for moving-coil loudspeakers. Special emphasis is placed on the defects resulting from loudspeaker nonlinearities. As a loudspeaker operates in the large signal domain, nonlinear distortions may arise and impair sound quality. Analysis of nonlinear responses can shed light on potential design faults of a loudspeaker. By exploiting this fact, this expert diagnostic system enables classification of design faults using a defect database alongside an intelligent fault inference module. Six types of defects are investigated in this paper. A large signal model based on electromechanical analogous circuits is employed for generating the defect database, through which a neural-fuzzy network is utilized for inferring the defect types. Numerical simulations and experimental investigations were undertaken for validating the loudspeaker diagnostic system. (C) 2009 Acoustical Society of America. [DOI: 10.1121/1.3058639]
Effect of connectivity and wettability on the relative permeability of NAPLs
(2009-02-01)
Chang, Liang-Cheng
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Chen, Hung-Hui
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Shan, Hsin-Yu
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Tsai, Jui-Pin
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土木工程學系
The characteristic relationships among relative permeability (K(r)), saturation (S) and capillary pressure (P) of NAPLs are the important constitutive laws to simulate the NAPLs flow in the subsurface. In this study, a micro model was used to obtain the values of permeability, saturation for the multi-phase flow of five fluid-pairs. The perspective micro model allows one to clearly observe the multiphase flow and allow this study to precisely measure the fluid saturation by digital image analysis. The experimental results showed hysteresis phenomenon of relative permeability versus saturation and that was not interpreted by previous studies. By carefully examining the recorded images, this study found that the degree of the connectivity for the micro channel occupied by wetting phase fluid could influence the relative permeability. Therefore, for the same saturation, the relative permeability in the imbibition is higher than that in the drainage. The results of the K(r)-S experiments for five fluid-pairs also showed that the residual saturation of wetting phase fluid decreased with the wettability increasing but increased with the interfacial tension increasing. Those interpretations and experimental results are valuable references for groundwater remediation and oil reservoir development.
Johnson's rule, composite jobs and the relocation problem
(2009-02-01)
Cheng, T. C. E.
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Lin, B. M. T.
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
Two-machine flowshop scheduling to minimize makespan is one of the most well-known classical scheduling problems. Johnson's rule for solving this problem has been widely cited in the literature. We introduce in this paper the concept of composite job, which is an artificially constructed job with processing times such that it will incur the same amount of idle time oil the second machine as that incurred by a chain of jobs in a given processing sequence. This concept due to Kurisu first appeared in 1976 to deal with the two-machine flowshop scheduling problem involving precedence constraints among the jobs. We show that this concept can be applied to reduce the computational time to solve some related scheduling problems. We also establish a link between solving the two-machine flowshop makespan minimization problem using Johnson's rule and the relocation problem introduced by Kaplan. We present an intuitive interpretation of Johnson's rule in the context of the relocation problem. (c) 2007 Elsevier B.V. All rights reserved.
Performance Improvement of Polycrystalline Silicon Nanowire Thin-Film Transistors by a High-k Capping Layer
(2009-02-01)
Lee, Ko-Hui
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Hsu, Hsing-Hui
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Lin, Horng-Chih
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Huang, Tiao-Yuan
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電子工程學系及電子研究所
In this work, a novel polycrystalline silicon (poly-Si) nanowire thin-film transistor (NW-TFT) with side-gated configuration and a high-k material capping was fabricated and characterized. It was found that the gate fringing field effect via the high-k passivation layer can effectively improve the device performance in terms of higher ON current, larger ON/OFF current ratio, and steeper subthreshold slope (SS). The drain-induced barrier lowering (DIBL) effect is also effectively suppressed owing to better gate control. (C) 2009 The Japan Society of Applied Physics
Investigating Importance Weighting of Satisfaction Scores from a Formative Model with Partial Least Squares Analysis
(2009-02-01)
Wu, Chia-Huei
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Chen, Lung Hung
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Tsai, Ying-Mei
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經營管理研究所
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Institute of Business and Management
This study introduced a formative model to investigate the utility of importance weighting on satisfaction scores with partial least squares analysis. Based on the bottom-up theory of satisfaction evaluations, the measurement structure for weighted/unweighted domain satisfaction scores was modeled as a formative model, whereas the measurement structure for global satisfaction scores was modeled as a reflective model according to top-down theory. The purpose was to see if the predictive effect of importance-weighted domain satisfaction scores is stronger than unweighted domain satisfaction scores in predicting global satisfaction scores. Three datasets in life, self, and job satisfaction were analyzed. In the life satisfaction dataset, 237 undergraduates at Central Taiwan University of Science and Technology voluntarily provided their responses. The mean age of respondents was 20.80 years (SD = 1.05). In the self-satisfaction dataset, 269 undergraduates at National Taiwan University provided their responses. The mean age of respondents was 19.78 years (SD = 1.44). Finally, in the job satisfaction dataset, 557 staff members in seven Taiwan provincial hospitals provided their responses. The mean age of respondents was 35.87 years (range from 21 to 65, SD = 8.60). Three measures of domain satisfaction, domain importance, and global satisfaction were collected in each dataset. Partial least squares analysis was used in model estimation. All the results revealed that unweighted domain satisfaction scores have a stronger predictive effect for global satisfaction measures than importance-weighted domain satisfaction scores, indicating that importance weighting on satisfaction scores did not have an empirical benefit.
I Want Products My Own Way, But Which Way? The Effects of Different Product Categories and Cues on Customer Responses to Web-based Customizations
(2009-02-01)
Chang, Chia-Chi
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Chen, Hui-Yun
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管理科學系
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Department of Management Science
Mass customization is a strategy that has been adopted by companies to tailor their products in order to match customer needs more precisely. Therefore, to fully capture the value of mass customization, it is crucial to explore how customers react to mass customization. In previous studies, an implied premise has been that consumers are keen to embrace customized products, and this assumption has also been treated by firms as a prerequisite for successful mass customization strategies. However, an undesirable complexity may result from difficult configuration processes that may intimidate and confuse some customers. Hence, this study explores strategies that marketers can employ to facilitate the customization process. Specifically, this study investigates how to enhance customer satisfaction and purchase decision toward customized products by providing cues compatible with the product category. It is hypothesized that for search products, customers rely more on intrinsic cues when making configuration decisions. On the other hand, for experience products, customers perceive extrinsic cues to be more valuable in assisting them to make configuration decisions. The results suggest that consumers tend to respond more favorably toward customized search products when intrinsic cues are provided than when extrinsic or irrelevant ones are provided. In contrast, when customizing experience products, customers tend to depend more on extrinsic cues than on intrinsic or irrelevant ones.
Selective Device Structure Scaling and Parasitics Engineering: A Way to Extend the Technology Roadmap
(2009-02-01)
Wei, Lan
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Deng, Jie
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Chang, Li-Wen
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Kim, Keunwoo
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Chuang, Ching-Te
We propose a path for extending the technology roadmap when currently considered technology boosters (e.g., strain, high-kappa/metal gate) reach their limits and physical gate length can no longer be effectively scaled down. By judiciously engineering the device parasitic resistance and parasitic capacitance, and considering the impact of the interconnect wiring capacitance, we propose scenarios of selective device structure scaling that will enable technology scaling and contacted gate pitch scaling for several generations beyond the currently perceived limits.
An overview of theory and practice on process capability indices for quality assurance
(2009-02-01)
Wu, Chien-Wei
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Pearn, W. L.
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Kotz, Samuel
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工業工程與管理學系
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Department of Industrial Engineering and Management
Process capability indices (PCIS), C(p), C(a), C(pk), C(pm), and C(pmk) have been developed in certain manufacturing industry as capability measures based on various criteria, including process consistency, process departure from a target, process yield, and process loss. It is noted in certain recent quality assurance and capability analysis works that the three indices, C(pk), C(pm), and C(pmk) provide the same lower bounds on the process yield. In this paper, we investigate the behavior of the actual process yield, in terms of the number of non-conformities (in ppm), for processes with fixed index values of C(pk) = C(pm) = C(pmk), possessing different degrees of process centering. We also extend Johnson's [1992. The relationship of C(pm) to squared error loss. journal of Quality Technology 24, 211-215] result formulating the relationship between the expected relative squared loss and PCIs. Also a comparison analysis among PCIs is carried out based on various criteria. The result illustrates some advantages of using the index C(pmk) over the indices C(pk) and C(pm) in measuring process capability (yield and loss), since C(pmk) always provides a better protection for the customers. Additionally, several extensions and applications to real world problem are also discussed. The paper contains some material presented in the Kotz and Johnson [2002. Process capability indices-a review, 1992-2000. journal of Quality Technology 34(1),1-19] survey but from a different perspective. It also discusses the more recent developments during the years 2002-2006. (C) 2009 Elsevier B.V. All rights reserved.
Application of Pd/Ge/Cu alloyed ohmic contact system to n-type GaAs for fully Cu-metallized InGaP/GaAs HBTs
(2009-02-01)
Chen, Ke-Shian
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Chang, Edward Yi
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Lin, Chia-Ching
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Lee, Cheng-Shih
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材料科學與工程學系
Use of the Pd/Ge/Cu multilayers as the emitter and collector ohmic metal for the fully Cu-metallized InGaP/GaAs heterojunction bipolar transistors is studied. The Pd/Ge/Cu ohmic contact exhibited a very low contact resistance of 5.73 x 10(-7) Omega cm(2) at a low annealing temperature (250 degrees C) and the microstructure evolution of Pd/Ge/Cu ohmic contact was investigated using transmission electron microscopy and energy dispersive spectrometer. We also did some comparisons between the Pd/Ge/Cu, Pd/Ge/Ti/Pt/Cu, and the traditional Au/Ge/Ni/Au ohmic contact structures to n-type GaAs. The common emitter I-V curves and Gummel plot of these Cu-metallized HBTs using Pd/Ge/Cu ohmic contact and Cu interconnects showed similar electrical characteristics as those HBTs with conventional Au-metallization. The cutoff frequency (f(T)) of 3 x 20-mu m-emitter-area devices was about 38 GHz. During both the current-accelerated stress test (110 kA/cm(2) stress for 24 h) and the thermal stability test (annealing at 250 degrees C for 24 h), the fully Cu-metallized HBT with Pd/Ge/Cu ohmic contact and Cu interconnects showed almost no obvious degradation in electrical characteristics. The results show that the Pd/Ge/Cu ohmic contact in combination with the Cu interconnects can be used on HBT devices to achieve the Au-free fully Cu-metallized lnGaP/GaAs HBTs, and the devices exhibit good device performance. (C) 2008 Elsevier Ltd. All rights reserved.
Feasibility study of high performance field emitter pattern with the horizontally oriented carbon nanotubes by electrophoresis
(2009-02-01)
Lin, Chen-Chun
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Chen, Ying-Chun
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Wang, Terry
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Kuo, Cheng-Tzu
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材料科學與工程學系
For the field emitter applications, electrophoretic deposition (EPD) followed by post air annealing treatment was developed to selectively deposit the single-walled carbon nanotubes (SWNTs) pattern made of Al and SiO(2) coatings. The EPD was conducted from a solution mixture of SWNTs and various dispersants or surfactants, including sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide and trictylphosphine oxide. Effects of the processing parameters of EPD and the post air annealing treatment on SWNTs dispersion, morphology, field emission (FE), and film-substrate adhesion were examined. The results indicate that the SIDS is the best surfactant in terms of SWNTs dispersion and solution stability, and the EPD parameters have no significant effects on their FE and adhesion properties of the deposited films. However. a higher post annealing temperature combined with an optimum annealing time is required to improve the film-substrate adhesion, so to reduce its electrical resistance and to enhance FE properties. The high performance annealed films with negligible internal stress are made of the micro-sized islands with the horizontally oriented SWNTs between them. The results also show that the pattern made of conductive and nonconductive coatings, such as Al and SiO(2), can be successfully used to deposit SWNTs pattern by EPD. (c) 2008 Published by Elsevier B.V.
An experimental study of the heat transfer in PS foam insulation
(2009-02-01)
Tseng, Pen-Chang
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Chu, Hsin-Sen
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機械工程學系
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Department of Mechanical Engineering
Heat transfer mechanisms in 14 samples of vacuum insulation panels (VIPs) are examined to reveal the influence of porous foam structure on VIP performance. The samples were produced by in-house equipment that was able to vary the foam structure by modulating the process temperature and pressure. Two parameters are proposed to describe the foam structure, namely, the broken cell ratio and the average cell size. Under a specific solid volume fraction, the average cell size shows a linear dependence on the broken cell ratio. Furthermore, the radiation and conduction heat transport data correlate well with these parameters. Radiation heat transfer increases as the broken cell ratio (cell size) increases, but solid conduction decreases as the broken cell ratio (cell size) increases. Consequently, an optimum broken cell ratio (cell size) exists such that the total heat transport is minimum under a specific solid volume fraction. However, the majority of VIP heat transfer is solid conduction. Solid conduction accounts for more than 80% of the total heat transport and is largely affected by the solid volume fraction. A rule of thumb for improving VIP performance is to reduce the solid volume fraction as much as possible to eliminate solid conduction, and maintain the cell size at an optimum value that is dependent on the solid volume fraction.
Criteria for the evaluation of linear two-port stability using two geometrically derived parameters
(2009-02-01)
Meng, Chinchun
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Wei, Hung-Ju
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Sun, Po-Hsing
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電信工程研究所
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Institute of Communications Engineering
Two geometrically derived stability parameters, mu' (or mu) and nu' (or nu), are used to analyze the stability of a two-port network. The magnitudes of both mu' (or nu) and nu' (or nu) parameters determine geometrical relations between the stability circle and the unit Smith chart in the Gamma(S) (or Gamma(L)) plane, vertical bar mu'vertical bar (or vertical bar mu vertical bar) is defined as the minimum distance from the stability circle to the origin of the unit Smith chart in the Gamma(S) (or Gamma(L)) plane, while vertical bar nu'vertical bar (or vertical bar nu vertical bar) is defined as the maximum distance. Moreover, the signs of nu' (or nu) and mu' (or mu) parameters determine which region of the stability circle is stable (inside or outside) and whether the stable region includes the origin of the Smith chart, respectively. There are totally 12 situations between the stability circle and the unit Smith chart in the Gamma(S) (or Gamma(L)) plane by using mu' (or mu) and nu' (or nu) parameters. This paper classifies 12 situations in the Gamma(S) plane and also presents the corresponding practical two-port networks.
Ordinal Optimization of G/G/1/K Polling Systems with k-Limited Service Discipline
(2009-02-01)
Horng, S. -C.
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Lin, S. -Y.
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電控工程研究所
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Institute of Electrical and Control Engineering
In this paper, we propose an ordinal optimization theory based algorithm to solve the optimization problem of G/G/1/K polling system with k-limited service discipline for a good enough solution using limited computation time. We assume that the arrival rates do not deteriorate visibly within a very short period. Our approach consists of two stages. In the first stage, we employ a typical genetic algorithm to select N=1024 roughly good solutions from the huge discrete solution space Omega using an offline trained artificial neural network as a surrogate model for fitness evaluation. The second stage consists of several substages to select estimated good enough solutions from the previous N, and the solution obtained in the last substage is the good enough solution that we seek. Using numerous tests, we demonstrate: (i) the computational efficiency of our algorithm in the aspect that we can apply our algorithm in real-time based on the arrival rate assumption; (ii) the superiority of the good enough solution, which achieves drastic objective value reduction in comparison with other existing service disciplines. We provide a performance analysis for our algorithm based on the derived models. The results show that the good enough solution that we obtained is among the best 3.31x10(-6)% in the solution space with probability 0.99.
Biomedical nanoparticle carriers with combined thermal and magnetic responses
(2009-02-01)
Liu, Ting-Yu
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Hu, Shang-Hsiu
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Liu, Dean-Mo
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Chen, San-Yuan
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Chen, I-Wei
Several biocompatible polymers are capable of large responses to small temperature changes around 37 degrees C In water, their responses include shrinkage and swelling as well as transitions in wettability. These properties have been harnessed for biomedical applications such as tissue engineering scaffolds and drug delivery carriers. A soft material/hard material hybrid in which a magnetic: metal or oxide is embedded in a temperature-responsive polymer matrix can combine the thermal sensitivity with magnetic signatures. Importantly, nanosizing such construct brings about new desirable features of extremely fast thermal response time, small magnetic hysteresis and enhanced magnetic susceptibility. Remote magnetic maneuvering and heating of the hybrid nanocolloids makes possible such applications as high-throughput enzyme separation and cell screening. Robust drug release on demand may also be obtained using these colloids and nanoparticle-derived thin film devices of combined thermal magnetic sensitivity. (C) 2008 Elsevier Ltd. All rights reserved.
A Broadband and Scalable Lossy Substrate Model for RF Noise Simulation and Analysis in Nanoscale MOSFETs With Various Pad Structures
(2009-02-01)
Guo, Jyh-Chyurn
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Tsai, Yi-Hsiu
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
An enhanced lossy substrate model is developed with important features of broadband accuracy and scalability. The broadband accuracy is justified by a good match with open pad S-parameters measured up to 110 GHz and MOSFETs' S- and Y-parameters over 40 GHz. The proven model can accurately simulate four noise parameters (NF(min), R(n), Re(Y(opt)), and Im(Y(opt))) and power spectral density of current noises (S(id) and S(ig)). The scalability has been validated over nanoscale MOSFETs with different finger numbers and adopting various pad structures (lossy, normal, and small pads). This scalable lossy substrate model attributed to two substrate RLC networks under the pads and transmission lines (TMLs) can consistently predict the abnormally strong finger number dependence and nonlinear frequency dependence of noise figure (NF(min)) revealed in devices with lossy pads. The enhanced model is useful in guiding pad and TML layouts for effective reduction of extrinsic noises and low noise design. Using a normal pad structure, the NF(min) can be effectively suppressed to approach the intrinsic performance, which is nearly independent of finger numbers.
Electrophoretic deposition of PtRu nanoparticles on carbon nanotubes for methanol oxidation
(2009-02-01)
Hsu, Yu-Kuei
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Yang, Ju-Lan
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Lin, Yan-Gu
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Chen, San-Yuan
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Chen, Li-Chyong
Electrophoretic deposition technique was successfully utilized to deposit the PtRu nanoparticles on carbon nanotubes, which were directly grown on carbon cloths (CNTs/CC). We applied an external dc field to drive the PtRu nanoparticles. which were surrounded by negatively charged glycolate in an ethylene glycol process, toward the positively biased CNTs. Systematic studies to achieve optimal size and loading amount by varying the bias potential and deposition time have been carried out. An average PtRu particle size of 2.08 nm with catalytic activity of 1.6 A/cm(2)/mg in electro-oxidation methanol could be achieved, which is highly desirable for fuel cell applications. (C) 2008 Published by Elsevier B.V.
FORMOSAT-3/COSMIC Spacecraft Constellation System, Mission Results, and Prospect for Follow-On Mission
(2009-02-01)
Fong, Chen-Joe
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Yen, Nick L.
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Chu, Chung-Huei
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Yang, Shan-Kuo
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Shiau, Wen-Tzong
The FORMOSAT-3/COSMIC spacecraft constellation consisting of six LEO satellites is the world's first operational GPS Radio Occultation (RO) mission. The mission is jointly developed by Taiwan's National Space Organization (NSPO) and the United States' UCAR in collaboration with NSF, USAF, NOAA, NASA, NASA's Jet Propulsion Laboratory, and the US Naval Research Laboratory. The FORMOSAT-3/COSMIC satellites were successfully launched from Vandenberg US AFB in California at 0 140 UTC 15 April 2006 into the same orbit plane of the designated 516 km altitude. The mission goal is to deploy the six satellites into six orbit planes at 800 kin altitude with a 30-degree separation for evenly distributed global coverage. All six FORMOSAT-3/COSMIC satellites are currently maintaining a satisfactory good state-of-health. Five out of six satellites have reached their final mission orbit of 800 kin as of November 2007. The data as received by FORMOSAT-3/COSMIC satellites constellation have been processed in near real time into 2500 good ionospheric profiles and 1800 good atmospheric profiles per day. These have outnumbered the worldwide radiosondes (similar to 900 mostly over land) launched from the ground per day. The processed atmospheric RO data have been assimilated into the Numerical Weather Prediction (NWP) models for real-time weather prediction and typhoon/hurricane forecasting by many major weather centers in the world. This paper describes the FORMOSAT-3/COSMIC satellite constellation system performance and the mission results that span the period from April 2006 to October 2007; and reviews the prospect of a future follow-on mission.
Single-Stage Soft-Switching AC-DC Converter With Input-Current Shaping for Universal Line Applications
(2009-02-01)
Liu, Yen-Ming
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Chang, Lon-Kou
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電控工程研究所
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Institute of Electrical and Control Engineering
In this paper, a novel single-stage soft-switching ac-dc converter for universal line applications is presented. Unlike the conventional single-stage designs, the proposed input-current shaping scheme is intentionally arranged to be charged in the duty-off time. With this design, the switch current stress in the duty-on time is significantly reduced. Meanwhile, this design produces ac modulation effect on the charging time of the boost inductor so that the input i-v curve drawn by the proposed converter has nearly linear relationship. Moreover, an active-clamp flyback-forward topology is used as the downstream de-de cell to alleviate voltage stress across the bulk capacitor. By deactivating the flyback subconverter and keeping the forward subconverter supplying the output power at light-load condition, the bulk-capacitor voltage can be alleviated effectively and guaranteed below 450 V in wide ranges of output load and line input (90-265 V(rms)). Experimental results, obtained from a prototype circuit with 20-V/100-W output, have verified that three achievements can be obtained simultaneously, including the compliance with the line-current harmonic regulations, the reliable alleviation of the bulk-capacitor voltage stress, and the substantially promoted conversion efficiency.
Accurate Rank Ordering of Error Candidates for Efficient HDL Design Debugging
(2009-02-01)
Jiang, Tai-Ying
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Liu, Chien-Nan Jimmy
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Jou, Jing-Yang
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
When hardware description languages (HDLs) are used in describing the behavior of a digital circuit, design errors (or bugs) almost inevitably appear in the HDL code of the circuit. Existing approaches attempt to reduce efforts involved in this debugging process by extracting a reduced set of error candidates. However, the derived set can still contain many error candidates, and finding true design errors among the candidates in the set may still consume much valuable time. A debugging priority method [21] was proposed to speed up the error-searching process in the derived error candidate set. The idea is to display error candidates in an order that corresponds to an individual's degree of suspicion. With this method, error candidates are placed in a rank order based on their probability of being an error. The more likely an error candidate is, a design error (or a bug), the higher the rank order that it has. With the displayed rank order, circuit designers should find design errors quicker than with blind searching when searching for design errors among all the derived candidates. However, the currently used confidence score (CS) for deriving the debugging priority has some flaws in estimating the likelihood of correctness of error candidates due to the masking error situation. This reduces the degree of accuracy in establishing a debugging priority. Therefore, the objective of this work is to develop a new probabilistic confidence score (PCS) that takes the masking error situation into consideration in order to provide a more reliable and accurate debugging priority. The experimental results show that our proposed PCS achieves better results in estimating the likelihood of correctness and can indeed suggest a debugging priority with better accuracy, as compared to the CS.