Browsing by Issue Date, starting with "2003-07-01"

Now showing 1 - 20 of 72566

Identification of trans-regulatory factors of the efflux pumps involved in drug resistance in Candida albicans.
(2003-07-01)
Chen, CG
;
Shih, HI
;
Yang, YL
;
Lo, HJ
;
生物科技學系
Fiber-lens-based module for optical recording applications
(2003-07-01)
Tien, CH
;
Chou, HL
;
Chiu, Y
;
Hsu, W
;
Milster, TD
An optical fiber-lens-type pickup with numerical aperture (NA) congruent to 0.27 was demonstrated for thermal recording of continuous 1.6-mum-wide lines on MO disks with 50% throughput efficiency. Moreover, a Si-micromachined near-field module integrated with a fiber lens, solid immersion lens (SIL), and submicron aperture was fabricated to improve the mechanical fragility and increase the NA of the optical-fiber-based pickup. The preliminary configuration design and measurement suggest the feasibility of the module as a submicron heat source for high-density optical data storage.
An enhanced congestion avoidance mechanism for TCP vegas
(2003-07-01)
Chan, YC
;
Chan, CT
;
Chen, YC
;
資訊工程學系
;
Department of Computer Science
TCP Vegas detects network congestion in the early stage and successfully prevents periodic packet loss that usually occurs in traditional schemes. It has been demonstrated that TCP Vegas achieves much higher throughput than TCP Reno. However, TCP Vegas cannot prevent unnecessary throughput degradation when congestion occurs in the backward path. In this letter, we propose an enhanced congestion avoidance mechanism for TCP Vegas. By distinguishing whether congestion occurs in the forward path or not, it significantly improves the connection throughput when the backward path is congested.
On topology improvement of a packet radio network by power control
(2003-07-01)
Huang, CF
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
The packet radio network (PRN) is an attractive architecture to support wireless data communication. The code assignment problem in PRN is a classical problem that has been extensively studied. However, in this paper, we observe that the power control issue has been ignored by most works but may have significant impact on the PRN's performance. Given a set of PRN stations, the network topology can be changed by adjusting each station's transmission power. All existing works, nevertheless, assume that the network topology is given before solving the code assignment problem. In this paper, we regard code assignment as an independent problem and show how to improve the network topology by power adjustment without violating the original code assignment. The improvement in topology (such as more links in the network) may result in improvement in network throughput. Through simulations, we demonstrate that although the code assignment problem is NP-complete, our power adjustment schemes can easily improve the network performance by about 10% with polynomial costs.
A parallel monotone iterative method for the numerical solution of multi-dimensional semiconductor Poisson equation
(2003-07-01)
Li, YM
;
友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
Various self-consistent semiconductor device simulation approaches require the solution of Poisson equation that describes the potential distribution for a specified doping profile (or charge density). In this paper, we solve the multi-dimensional semiconductor nonlinear Poisson equation numerically with the finite volume method and the monotone iterative method on a Linux-cluster. Based on the nonlinear property of the Poisson equation, the proposed method converges monotonically for arbitrary initial guesses. Compared with the Newton's iterative method, it is easy implementing, relatively robust and fast with much less computation time, and its algorithm is inherently parallel in large-scale computing. The presented method has been successfully implemented; the developed parallel nonlinear Poisson solver tested on a variety of devices shows it has good efficiency and robustness. Benchmarks are also included to demonstrate the excellent parallel performance of the method. (C) 2003 Elsevier B.V. All rights reserved.
DiffServ edge routers over network processors: Implementation and evaluation
(2003-07-01)
Lin, YD
;
Lin, YN
;
Yang, SC
;
Lin, YS
;
資訊工程學系
Network processors are emerging as a programmable alternative to the traditional ASIC-based solutions in scaling up the data plane processing of network services. This work, rather than proposing new algorithms, illustrates the process of, and examines the performance issues in, prototyping a DiffServ edge router with IXP1200. The external benchmarks reveal that although the system can scale to wire speed of 1.8 Gb/s in simple IP forwarding, the throughput declines to 180-290 Mb/s when. DiffServ is performed due to the double bottlenecks of SRAM and microengines. Through internal benchmarks, the performance bottleneck was found to be able to shift from one place to another en different network services and algorithms. Most of the results reported here should be applicable to other NPs since they have similar architectures and components.
Stability investigation of single-wafer process by using a spin etcher
(2003-07-01)
Kang, TK
;
Wang, CC
;
Tsui, BY
;
Yang, WL
;
Chien, FT
Etch rate instability was found in a spin etcher. When chemical was pumped to the spin etcher, the flow rate became unstable; possibly resulting in a chemical deficiency due to low mass transport at the wafer edge. Consequently, the etch rate and etch uniformity are unstable. The detailed etch mechanism has been investigated and the mass transport deficiency can be avoided. Less than 2% of etch nonuniformity and a stable process can be achieved by achieving a stable flow rate and control of the surface reaction over the whole wafer in spin etching. (C) 2003 The Electrochemical Society.
A priority TCAM IP-Routing lookup scheme
(2003-07-01)
Lin, PC
;
Chang, CJ
;
電信工程研究所
;
Institute of Communications Engineering
A priority TCAM IP-routing lookup scheme, which combines a priority ternary content addressable memory (TCAM) technique with a compact IP-routing lookup scheme, is proposed in this letter. It not only completes an IP-routing lookup with two memory accesses but also achieves small lookup table size and fast table reconstruction time.
Physical and barrier properties of plasma-enhanced chemical vapor deposited alpha-SiC : H films from trimethylsilane and tetramethylsilane
(2003-07-01)
Chiang, CC
;
Chen, MC
;
Ko, CC
;
Wu, ZC
;
Jang, SM
This work investigates the thermal stability and physical and barrier properties of two species of plasma-enhanced chemical vapor deposited (PECVD) alpha-SiC:H silicon carbide films (with k-values less than 5) deposited using trimethylsilane, (CH3)(3)SiH (3MS) and tetramethylsilane, (CH3)(4)Si (4MS) organosilicate gases. It is found that the 4MS alpha-SiC:H film contains a higher content of carbon and has a lower dielectric constant. Both of the 3MS and 4MS alpha-SiC:H films are thermally stable at temperatures up to 500degreesC. However, degraded barrier property and moisture resistance were observed for the 4MS alpha-SiC:H film; this is attributed to the porosity enrichment caused by the film's high carbon content. The 3MS alpha-SiC:H film, which exhibits a superior Cu-barrier property, is a potential candidate for replacing the higher dielectric constant Si3N4 film as a Cu-cap barrier and etching stop layer in the Cu damascene structure.
Automatic schedule integration for highway projects
(2003-07-01)
Dzeng, RJ
;
Wang, WC
;
土木工程學系
;
Department of Civil Engineering
The construction of a highway/expressway, which involves a complex combination of roads, bridges, and tunnels, is generally separated into several projects. Various contractors thus execute different projects and often apply differing scheduling practices. Since all projects involved in highway construction must be completed for the highway to be useful, the management of the various projects should preferably be integrated. To assist project controllers in schedule integration, this study proposes algorithms based on standardized codes and network modules. A computer system was also designed to help contractors use these modules for scheduling, and ultimately to let project controllers combine these schedules electronically. A questionnaire survey and industry feedback revealed the potential benefits of using the proposed algorithms for generating and integrating schedules, respectively. Contractors' computation capabilities must be improved before the proposed scheduling algorithms can be fully implemented. (C) 2003 Elsevier Science B.V. All rights reserved.
A dynamic thermal management circuit for system-on-chip designs
(2003-07-01)
Chiueh, H
;
Draper, J
;
Choma, J
;
電信工程研究所
;
Institute of Communications Engineering
A novel fully integrated dynamic thermal management circuit for system-on-chip design is proposed. Instead of worst-case thermal management used in conventional systems, this design yields continual monitoring of thermal activity and reacts to specified conditions. With the above system, we are able to incorporate on-chip power/speed modulation and integrated multi-stage fan controllers, which allows us to achieve nominal power dissipation and ensure operation within specification. Both architecture and circuitry are optimized for modern system-on-chip designs. This design yields intricate control and optimal mangement with little system overhead and minimum hardware requirements, as well as provides the flexibility to support different thermal mangement algorithms.
Minimum copper loss flux-weakening control of surface mounted permanent magnet synchronous motors
(2003-07-01)
Chen, JJ
;
Chin, KP
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機械工程學系
;
Department of Mechanical Engineering
This study presents a novel current loop design method capable of automatic flux-weakening control with minimum copper loss for surface mounted permanent magnet synchronous motors (SPMSM). The proposed current controller can automatically re-compute the d-axis current command to defer output voltage saturation. Consequently, the motor operations in the flux-weakening region are also contained in the stable operating region. Analysis results indicate that since the output voltage vector in the flux-weakening region produced by this controller is consistently on the boundary of the maximum output voltage vector allowed by the inverter, the corresponding flux-weakening current is the optimal value in the sense of minimum copper loss. This minimum copper loss design differs from the maximum output torque design and the constant power design of the flux-weakening control methods found in the literature. Experimental results further demonstrate the feasibility of the proposed current controller and its ability to maximize the speed range of the motor drive for a given inverter capacity.
An untraceable blind signature scheme
(2003-07-01)
Hwang, MS
;
Lee, CC
;
Lai, YC
;
資訊工程學系
;
Department of Computer Science
In this paper, the authors intend to propose a new untraceable blind signature scheme based on the RSA cryptosystem. This paper applies the Extended Euclidean algorithm to our blind signature scheme. Compared with other blind signature schemes, our proposed scheme can meet the all requirements of a blind signature scheme. The security of the proposed scheme, as did that of the RSA cryptosystem, depends on the difficulty of solving the factoring problem.
Characteristics of the erbium doped fiber amplifier with polarization mode dispersion compensation
(2003-07-01)
Dung, JC
;
Chi, S
;
Chen, CC
;
光電工程學系
;
Department of Photonics
We have experimentally demonstrated the characteristics of the reflective type erbium-doped fiber amplifier (R-EDFA) which is composed of a circulator and a Faraday rotator mirror. It is shown that the gain spectrum of the R-EDFA is shifted to longer wavelength when compared with that of the conventional single-pass EDFA. For the R-EDFA. the forward pumping is better than the backward pumping in gain and noise figure. Besides, the reflective structure can be used as a broad band light source because its ASE spectrum is wider and the output power is higher. We also show that, by using the reflective type configuration, the polarization dependent gain is reduced and the polarization mode dispersion of EDF can be completely compensated but the polarization mode dispersion from the circulator is still survived. (C) 2003 Elsevier Science B.V. All rights reserved.
Investigation of grain boundary control in the drain junction on laser-crystalized poly-Si thin film transistors
(2003-07-01)
Chen, TF
;
Yeh, CF
;
Lou, JC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This letter investigates the influences of grain boundaries in the drain junction on the performance and reliability of laser-crystalized poly-Si thin film transistors (TFTs). A unique test structure where the channel. region includes 150-nm-thick laser-crystalized poly-Si with, small grain sizes and a 100-nm-thick one with large grain sizes is fabricated. Different behaviors in the electrical characteristics and reliability of a single TFT are observed under measurements of the forward mode and then under first measurements of the reverse mode. This is due to the different number of, grain boundaries in the drain junction. Grain boundaries in the drain junction were found to cause reduced ON/OFF current ratio, variations in threshold voltage With drain bias, significantly, increased kink effect in the output characteristics, and poor hot-carrier stress endurance.
Effects of temperature on surface clusters by molecular dynamics simulation
(2003-07-01)
Jian, SR
;
Fang, TH
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
This article discusses the physical mechanisms for the evaporation phenomena of argon clusters on surfaces under various temperatures with the aid of molecular dynamics analysis by means of the Stoddard-Ford potential. Our simulated results indicate that the evaporation rate of the argon clusters increased drastically when the temperature was increased but the contact angle decreased. Furthermore, the thermal stability of the argon clusters is also discussed here. The evaporation mechanisms of argon clusters are clearly shown with the aid of molecular dynamics. (C) 2003 Elsevier Science B.V. All rights reserved.
Taiwanese science students' and teachers' perceptions of the laboratory learning environments: exploring epistemological gaps
(2003-07-01)
Tsai, CC
;
教育研究所
;
師資培育中心
;
Institute of Education
;
Center of Teacher Education
The purpose of this study was to explore the differences between science students' and teachers' perceptions of laboratory environments. More than 1000 junior high school students and their science teachers in Taiwan were surveyed. The students showed much more dissatisfaction with approaches to laboratory activities than their teachers. They preferred a much more student-cohesive, open-ended, integrated and rule-clear laboratory environment than their teachers expected or preferred. However, the teachers sampled showed higher preferences for better equipment and material environments for laboratory work than did their students. Data from follow-up interviews with participant teachers suggested that epistemological views about science might be one of the important factors causing differences in perceptions between students and teachers of laboratory learning environments.
A new duration modeling approach for Mandarin speech
(2003-07-01)
Chen, SH
;
Lai, WH
;
Wang, YR
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, a new duration modeling approach for Mandarin speech is proposed. It explicitly takes several major affecting factors as multiplicative companding factors (CFs) and estimates all model parameters by an EM algorithm. Besides, the three basic Tone 3 patterns (i.e., full tone, half tone and sandhi tone) are also properly considered via using three different Us to separate their affections on syllable duration. Experimental results showed that the variance of the syllable duration was greatly reduced from 180.17 to 2.52 frame(2) (1 frame =5 ms) by the syllable duration modeling to eliminate effects from those affecting factors. Moreover, the estimated Us of those affecting factors agreed well to our prior linguistic knowledge. Two extensions of the duration modeling method are also performed. One is the use of the same technique to model initial and final durations. The other is to replace the multiplicative model with an additive one. Lastly, a preliminary study of applying the proposed model to predict syllable duration for TTS is also performed. Experimental results showed that it outperformed the conventional regressive prediction method.
Via-filling capability of copper film by CVD
(2003-07-01)
Lin, CL
;
Chen, PS
;
Lin, YC
;
Tsui, BY
;
Chen, MC
The via-filling properties of chemically-vapor-deposition (CVD) Cu film filled in deep submicrometer vias (diam of 0.11, 0.15 and 0.18 mum) were investigated with respect to various deposition parameters. A superior void-free via-filling by Cu film can be achieved at low temperature, low pressure, and high concentration of precursor species in the gas phase. However, these favorable conditions for void-free via-filling of Cu film also lead to slightly degraded film properties, including higher resistivity, higher content of impurities, degraded adhesion to substrate, and lower deposition rate, as compared with those obtained under the optimal deposition condition. Thus, a trade-off is needed between void-free via-filling and a superior film property. The key to achieve a void-free via-filling is to have a high probability of a re-emission event for the Cu-containing species inside the vias. Using helium (He) as the carrier gas is preferable to using hydrogen (H-2), because the hydrogen reduction reaction would enhance the deposition of Cu, resulting in a decreased probability of a re-emission event and thus degrading the capability of void-free via-filling. In this study, we have achieved void-free filling by CVD Cu film in deep submicrometer 0.11 mm diam vias with an aspect ratio of 9.1 at and below deposition temperatures of 160degreesC, using a precursor flow rate of 0.4 cm(3)/min and at a deposition pressure of 60 mTorr. (C) 2003 The Electrochemical Society.
Study of titanium tungsten nitride and tungsten nitride Schottky contacts on n-GaN
(2003-07-01)
Lee, CS
;
Chang, EY
;
Chang, L
;
Fang, CY
;
Huang, YL
The Schottky diode behaviors of the TiWNx and the WNx Schottky contacts to n-GaN were investigated at different annealing temperatures. Both TiWNx and WNx films were deposited by the reactive DC sputtering method. The WNx/n-GaN contact exhibited excellent electrical characteristics even after rapid-thermal annealing up to 850degreesC for 10s. The ideality factor and barrier height remained 1.09 and 0.8OeV, respectively, after 850degreesC annealing. However, the TiWNx/n-GaN contact was thermally stable only up to 650degreesC annealing; the values of the ideality factor and the barrier height were 1.14 and 0.76 eV, respectively, after 650degreesC annealing and started to degrade when annealed at higher temperatures. The deterioration of the TiWNx/n-GaN contact at higher temperatures was due to the inter-diffusion of the TiWN film and the GaN material.