Browsing by Issue Date, starting with "2003-10-23"

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Scattering and guiding characteristics of waveguides with two-dimensionally periodic walls of finite thickness
(2003-10-23)
Hwang, RB
;
Peng, ST
;
友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
[1] Electromagnetic wave propagation along waveguides having two-dimensionally (2-D) periodic walls with finite thickness is formulated here as an exact boundary-value problem. The dispersion relation of such a class of waveguide is systematically analyzed in terms of both phase and attenuation constants. In addition, the contour map of field components and Poynting vector are also demonstrated in this paper to verify the guiding characteristics of such a class of waveguides. In particular, the strong couplings between an incident plane wave and waveguide modes phase-matching condition are carefully examined and are employed to identify the existence of waveguide modes.
Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent
(2003-10-23)
Kuo, JT
;
Chang, YJ
;
Tseng, CP
;
生物科技學系
;
Department of Biological Science and Technology
In contrast to the ribosomal RNA gene expression increasing with growth rate, transcription of the lac operon is downregulated by cell growth rate. In continuous culture, growth rate regulation of lac promoter was independent of carbon substrate used and its location on the chromosome. Since the lac operon is activated by cyclic adenosine monophosphate (cAMP), which decreases with increasing cell growth rate, expression of plac-lacZ reporter fusion was analyzed in cya mutant under various growth conditions. The results demonstrated that expression of plac-lacZ in cya mutant was both lower and growth rate independent. In addition, ppGpp (guanosine tetraphosphate) was not involved in the mechanism of growth rate regulation of the lac promoter. Thus, the results of this study indicate that cAMP mediates the growth rate-dependent regulation of lac operon expression in Escherichia coli. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.
Improvement of near-ultraviolet InGaN/GaN light-emitting diodes by inserting an in situ rough SiN(x) interlayer in n-GaN layers
(2003-10-27)
Tu, RC
;
Chuo, CC
;
Pan, SM
;
Fan, YM
;
Tsai, CE
Near-ultraviolet 400-nm InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with and without an in situ rough SiN(x) interlayer inserted into the n-GaN underlying layer were grown on c-face sapphire substrates by metalorganic vapor phase epitaxy. Inserting the SiN(x) interlayer into the n-GaN underlying layer slightly reduced leakage current induced by reducing the defect density. Additionally, an enhancement of light extraction for the LED with a SiN(x) interlayer is expected because of the increased intensity of light scattered on the SiN(x) nanomask, changing the directions of propagation of light. Consequently, the emission efficiency of an LED with an in situ rough SiN(x) interlayer doubles that without a SiN(x) interlayer. (C) 2003 American Institute of Physics.
Improvement of near-ultraviolet InGaN/GaN light-emitting diodes by inserting an in situ rough SiNx interlayer in n-GaN layers
(2003-10-27)
Tu, RC
;
Chuo, CC
;
Pan, SM
;
Fan, YM
;
Tsai, CE
Near-ultraviolet 400-nm InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with and without an in situ rough SiNx interlayer inserted into the n-GaN underlying layer were grown on c-face sapphire substrates by metalorganic vapor phase epitaxy. Inserting the SiNx interlayer into the n-GaN underlying layer slightly reduced leakage current induced by reducing the defect density. Additionally, an enhancement of light extraction for the LED with a SiNx interlayer is expected because of the increased intensity of light scattered on the SiNx nanomask, changing the directions of propagation of light. Consequently, the emission efficiency of an LED with an in situ rough SiNx interlayer doubles that without a SiNx interlayer. (C) 2003 American Institute of Physics.
Activation of the calcineurin-nuclear factor of activated T-cell signal transduction pathway in atrial fibrillation
(2003-10-28)
Lai, LP
;
Lin, CC
;
Lin, JL
;
Lin, CS
;
生物科技學系
Planar mode converter used in printed microwave integrated circuits
(2003-10-28)
Tzuang
;
Ching-kuang
;
Lee
;
Cheng-jung
A planar mode converter includes a rectangular waveguide, a microstrip feed-in circuit, and a microstrip feed-out circuit. The rectangular waveguide is filled with dielectric layers and surrounded with metal materials. The lowermost dielectric layer has usually largest thickness and dielectric constant. Except for the lowermost dielectric layer, each of the dielectric layers has a rectangular aperture at its front-end and back-end, respectively. The microstrip feed-in circuit is constituted by first, second and third metal strips, and a feed-in metal ground plane. The first metal strip and the feed-in metal ground plane form a feed-in signal line. The first, second and third metal strips are adhered to the top surface of the lowermost dielectric layer, and the feed-in metal ground plane is adhered to the bottom surface of the lowermost dielectric layer. The microstrip feed-out circuit is constituted of fourth, fifth and sixth metal strips, and a feed-out metal ground plane. The sixth metal strip and the feed-out metal strip form a feed-out signal line.
Evolution of the yeast protein interaction network
(2003-10-28)
Qin, H
;
Lu, HHS
;
Wu, WB
;
Li, WH
;
統計學研究所
To study the evolution of the yeast protein interaction network, we first classified yeast proteins by their evolutionary histories into isotemporal categories, then analyzed the interaction tendencies within and between the categories, and finally reconstructed the main growth path. We found that two proteins tend to interact with each other if they are in the same or similar categories, but tended to avoid each other otherwise, and that network evolution mirrors the universal tree of life. These observations suggest synergistic selection during network evolution and provide insights into the hierarchical modularity of cellular networks.
The electrochemical behavior of tin-doped indium oxide during reduction in 0.3 M hydrochloric acid
(2003-10-30)
Huang, CA
;
Li, KC
;
Tu, GC
;
Wang, WS
;
材料科學與工程學系
The electrochemical behavior of tin-doped indium oxide (ITO) on SiO2 in 0.3 M HCl was studied using voltammetric scanning method. The result showed that an obvious reduction current peak occurred during the first cathodic potential scanning. The reduction reaction became less active after annealing ITO at 500 C for 1 h. The result was attributed to the replenishment of oxygen-deficient site, which acts as current carrier, by the annealing treatment. Many spherical In-Sn particles with sizes about 100-500 nm were formed on the ITO surface adjacent to the grain boundary when the reduction current took place. The In-Sn particles initiated preferentially on the ITO surface near grain boundaries attending the dissolution of ITO grain boundary. In the scanning period, after completion of the reduction current peak, reduction of hydrogen ions occurred in more negative potential region. A schematic illustration for the formation mechanism of the In-Sn reduction particle was postulated based on the metallographical and electrochemical results in this work. (C) 2003 Elsevier Ltd. All rights reserved.
金氧半場效電晶體之閘極結構
(2003-11-01)
崔秉鉞
;
黃誌鋒
本發明係提出一種新的合金系統，用以解決金氧半場效電晶體金屬閘極功函數的不適性，促使表面通道電晶體起始電壓係可有效降低，達到低工作電壓之要求，本合金系統以化學性質不活潑且熱穩定性極佳的鉑金屬(Pt)為主成分，加入不同比例之低功函數材料，例如：鉭(Ta)或鈦(Ti)，以達成調整功函數之目的。合金閘的製作方法可以是同時濺鍍(co-sputter)或是同時蒸鍍(co-evaporation)的物理氣象沉積方式，依所需之成分調整鉑靶及低功函數金屬靶之沉積速率，以合成適當的鉑合金，亦可以使用事先合成之合金靶，以單純物理性濺鍍方式製作。
Characterizing trench-gate power metal-oxide-semiconductor field effect transistor with multi-layer dielectrics at the trench bottom
(2003-11-01)
Lin, MJ
;
Liaw, CW
;
Chang, FL
;
Cheng, HC
;
電子工程學系及電子研究所
Power devices with a high switching speed and a low conduction resistance are crucially important in power conversion circuits. In this study, a trench-gate power metal-oxide-semiconductor field effect transistor (MOSFET) with a high-density cell design 20.6 Mcell/cm(2) was implemented for the first time using multilayer dielectrics with an oxide-nitride-oxide (ONO) structure at the bottom of the trench. The thick ONO dielectric layers at the bottom of the trench compensate for the increase in Miller capacitance per unit area as the cell density increases. The resulting device exhibits excellent characteristics of gate charge, switching power loss, gate oxide quality and practical process stability, superior to those of the conventional structure. An n-channel 25.8 V trench gate MOSFET with a specific on-resistance of 0.15 mOmegam(2), and R-ON x Q(GD) figure-of-merit 41 mOmega.nC is presented.
Special section on bioinformatics - Foreword
(2003-11-01)
Hwang, JK
;
Kao, MY
;
Sun, CT
;
Hsu, WL
;
生物科技學系
Electromigration study in SnAg3.8Cu0.7 solder joints on Ti/Cr-Cu/Cu under-bump metallization
(2003-11-01)
Hsu, YC
;
Shao, TL
;
Yang, CJ
;
Chen, C
;
材料科學與工程學系
This paper investigates the electromigration-induced failures of SnAg3.8Cu0.7 flip-chip solder joints. An under-bump metallization (UBM) of a Ti/Cr-Cu/Cu trilayer was deposited on the chip side, and a Cu/Ni(P)/Au pad was deposited on the BT board side. Electromigration damages were observed in the bumps under a current density of 2 x 10(4) A/cm(2) and 1 x 10(4) A/cm(2) at 100 degreesC and 150 degreesC. The failures were found to be at the cathode/chip side, and the current crowding effect played an important role in the failures. Copper atoms were found to move in the direction of the electron flow to form intermetallic compounds (IMCs) at the interface of solder and pad metallization as a result of current stressing.
Flame stabilization over a Tsuji burner by four-step chemical reaction
(2003-11-01)
Tsa, SS
;
Chen, CH
;
機械工程學系
;
Department of Mechanical Engineering
This investigation applies a four-step chemical kinetics mechanism to implement the original combustion model developed by Chen and Weng (Combustion Science and Technology, Vol. 73, pp. 427-446, 1990). Comparing the blowoff curve of Tsuji (Progress in Energy and Combustion Science, Vol. 8, p. 93, 1982) with that of Chen and Weng reveals that this study yields a much better prediction than that in the latter reference. Also, the data in this study has an excellent agreement with the measured data of Dreier et al. (Berichtc der Bunsen-Gesellschaft-Physical Chemistry, Vol. 90, pp. 1010-1015, 1986). The interested parameter is the in flow velocity U-in. As U-in increases, the envelope diffusion flame, wake flame, liftoff flame, and another wake flame appear in that order before complete extinction. The formal wake flame is transformed from the envelope diffusion flame and the other is from the liftoff flame. The existence of a liftoff flame is verified by a corresponding experimental observation (Tsa et al., 2003). The maximal liftoff height is 1.7 D when U-in is 1.05 m/s, and this height is maintained up to U-in=1.09 m/s. Then the height declines gradually as the in flow velocity increases, which is a process that can be regarded as flashback. No recirculation flow exists behind the cylindrical burner for these liftoff flames. A transition from liftoff to wake flame occurs between 1.13 to 1.15 m/s. The wake flame reappears at U-in=1.16 m/s. Finally, the flame is extinguished completely when U-in>2.12 m/s. The flame's lifting and dropping back is explained.
Fuzzy multiple criteria selection of government-sponsored frontier technology R&D projects
(2003-11-01)
Hsu, YG
;
Tzeng, GH
;
Shyu, JZ
;
科技管理研究所
;
Institute of Management of Technology
Selection of government-sponsored frontier R&D projects is made difficult by the coexistence of the conflicting participating parties, the availability of experts for new frontier technology review, and the ambiguity of new frontier technology. This paper presents a model that includes (1) using the analytical hierarchy process (AHP) method to integrate various expectations from different interest groups into evaluating objectives/criteria, (2) the group-decision method by technical experts based on the predetermined objectives/criteria, and (3) the fuzzy approach in scoring the subjective judgments of the experts. The results reveal that differences of weights toward each criterion exist among various groups. The government and academia care more about social benefits, the researchers are more concerned about intellectual properties, and the experts from industry emphasize the importance of feasibility. The method presented in this paper was applied at a national research institute in Taiwan. The results reveal that: (1) the approach can solve the disparity between the profound knowledge required for evaluation and the different expectation from various interest groups, (2) the fuzzy approach is suitable to frontier technology R&D project selection because of the vagueness of the nature of frontier technology and the difficulties in evaluating quantitatively and accurately.
Decision of double-talk and time-variant echo path for acoustic echo cancelation
(2003-11-01)
Jenq, JC
;
Hsieh, SF
;
電信工程研究所
;
Institute of Communications Engineering
A new double-talk detection (DTD) method is proposed for acoustic echo cancelation (AEC) using the iterative maximal-length-correlation (IMLC) algorithm. Based on the assumption of uniformly distributed time-variant echo-path-change, we develop a simplified likelihood ratio test and plot the detection performance by a receiver operating characteristic. Computer simulation shows the proposed DTD method is effective in discriminating double-talk from time-variant echo-path-change.
Cost benefit analysis of series systems with warm standby components
(2003-11-01)
Wang, KH
;
Pearn, WL
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper deals with the cost benefit analysis of series systems with warm standby components. The time-to-repair and the time-to-failure for each of the primary and warm standby components is assumed to have the negative exponential distribution. We develop the explicit expressions for the mean time-to-failure, MTTF, and the steady-state availability, A(T)(infinity) for three configurations and perform a comparative analysis. Under the cost/benefit (C/B) criterion, comparisons are made based on assumed numerical values given to the distribution parameters, and to the cost of the components. The configurations are ranked based on: MTTF, A(T)(infinity), and C/B where B is either MTTF or A(T)(infinity).
Fabric evolution of granular assembly under K-0 loading/unloading
(2003-11-01)
Liou, JC
;
Pan, YW
;
土木工程學系
;
Department of Civil Engineering
This study attempted to investigate the fabric evolution in K-0 loading/unloading. The work made use of a field simulator to control K-0 loading/unloading in large specimens prepared by air-pluviation. In each loading stage, wave velocities along various propagation directions were measured. On the basis of the theories of micro-mechanics and wave propagation, the microscopic parameters of the granular assembly were back calculated to investigate the fabric evolution of granular soil during K-0 loading/unloading. In this study, the Geometric fabric was modelled by fabric tensors of ranks 2 and 4. The comparison of calibrated results using ranks 2 and 4 revealed the advantage of the usage of rank-4 fabric tensor in modelling fabric evolution in spite of its complexity. By comparing relative magnitudes of vertical and horizontal components of geometric fabric, it was demonstrated that relative constraint in lateral directions increased during K-0-unloading in order to maintain a K-0 condition. It revealed that fabric evolution was responsible for a higher K-0 in unloading than K-0 in loading. Copyright (C) 2003 John Wiley Sons, Ltd.
Electromigration studies of flip chip Sn95/Sb5 solder bumps on Cr/Cr-Cu/Cu under-bump metallization
(2003-11-01)
Shao, TL
;
Lin, KC
;
Chen, C
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The electromigration-induced failure of Sn95/Sb5 flip chip solder bumps was investigated. The failure of the joints was found at the cathode/chip side after current stressing with a density of 1 X 10(4) A/cm(2) at 150degreesC for 13 sec. The growth of intermetallic compounds (IMCs) was observed at the anode side after current stressing. Voids were found near the current crowding area in the cathode/chip side, and the (Cu,Ni)(6)Sn-5 IMC at the cathode/chip end was transformed into the Sn phase. The failure mechanism for Sn95/Sb5 flip chip solder joint is proposed in this paper.
A 30 V high voltage NMOS structure design in standard 5 VCMOS processes
(2003-11-01)
Lin, TC
;
Wu, JC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper describes the robust design of the 30 V high voltage NMOS (HVNMOS) structure implemented in a 0.6 mum 5 V standard CMOS processes without any additional masks or process steps. The structure makes use of the field oxide (FOX) and light doping N-well to increase the drain to gate and drain to bulk breakdown voltages, respectively. By varying the six spacing parameters: the channel length, gate overlap FOX, N-well overlap channel length, poly to the active area of the drain (OD2), metal extend beyond the OD2 and N-well extend beyond the OD2 in HVNMOS structure. the breakdown voltage can be improved. The experimental results show that the breakdown voltage of the normal NMOS is 11V, and the breakdown voltage of the HVNMOS is increased to over 30 V. With the optimized layout parameters of the HVNMOS, it can be increased to 38 V.
Electrically switching bistability of a chiral quasi-homeotropic liquid crystal device with low driving voltage
(2003-11-01)
Hsieh, CY
;
Chen, SH
;
光電工程學系
;
Department of Photonics
We report a new electrically switching bistable chiral quasi-homeotropic liquid crystal device with low driving voltage. This device is operated from the initial twisted-homeotropic state to either +90degrees or -270degrees twisted static state showing dark and bright transmittances, respectively, using different switching processes. The critical applied voltage to achieve the switching bistability of our device is only 4.3 V, which is approximately twice its threshold voltage for Freedericksz transition. In addition, the switching characteristics of this device with different driving waveforms are also investigated in this paper.