Browsing by Issue Date, starting with "2007-01-21"

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照度均勻的直下式背光模組裝置及其製法
(2007-01-21)
馮致華
;
陸懋宏
本發明提供一種直下式背光模組裝置，包括各式光源，如各型燈管、LED等，在光源上方之擴散板；其中，擴散板為鏤空之楔型構造，或引入多段式傾斜角，光經由光源發射後進入擴散板之鏤空區內，可將板內全反射的光及由鏤空構造導往兩旁的光，該區域光照度下降，但整個模組裝置之光均勻度上升。
雙抗諧振反射光波導馬赫任德干涉式感測器
(2007-01-21)
許世欣
;
黃遠東
本發明之雙抗諧振反射光波導(ARROW)馬赫任德干涉式感測器的用途在偵測外在環境的折射率變化，以供化學和生化感測之用。此一感測元件係由分光區域、感測區域及合光區域等三個區域構成，其中分光與合光區域的結構為具高耦合效率的雙抗諧振反射光波導，而感測區域則是不耦合之雙抗諧振反射光波導。藉由調整結構之對稱性以控制其耦合行為，可達成小巧且不使用彎折結構之積體化馬赫任德干涉式感測器。
助銲劑
(2007-01-21)
徐享文
;
黃和悅
;
曾光宏
;
林仁治
;
張肇芳
一種助銲劑，包含有一基質以及一活化添加物：基質係為氧化鉬，而活化添加物係選自氧化鐵、氧化矽，以及碳酸鎂所組成之群組；藉此，本發明可應用於碳鋼材料之銲接加工，提高銲接過程的銲道熔接深度，達到節省加工時間，減少整體製造成本之目的。
High power passively Q-switched ytterbium fiber laser with Cr4+: YAG as a saturable absorber
(2007-01-22)
Huang, J. Y.
;
Liang, H. C.
;
Su, K. W.
;
Chen, Y. F.
;
電子物理學系
We report an efficient high-peak-power and high-average-power passively Q-switched ytterbium fiber laser with a Cr4+: YAG crystal as a saturable absorber in an external-resonator configuration. At an incident pump power of 17.5 W, the passively Q-switched fiber laser produces an average power greater than 6.2 W with a pulse repetition rate of 48 kHz. The output pulses noticeably display a mode-locking phenomenon that leads to the maximum peak power to be higher than 20 kW. (c) 2007 Optical Society of America.
Tunable S-band erbium-doped triple-ring laser with single-longitudinal-mode operation
(2007-01-22)
Yeh, C. -H.
;
Huang, T. -T.
;
Chien, H. -C.
;
Ko, C. -H.
;
Chi, S.
We propose and demonstrate a tunable and stable single-longitudinal-mode (SLM) erbium fiber laser with a passive triple-ring cavity structure in S-band operation. The proposed laser is fundamentally structured by using three different lengths of ring cavities, which serve as the mode filters. When a mode-restricting intracavity fiber Fabry-Perot tunable filter (FFP-TF) is combined, the proposed resonator can guarantee a tunable and stable SLM laser oscillation. Moreover, the performances of the output power, wavelength stability, tuning range, and side-mode suppression ratio (SMSR) are studied. (c) 2007 Optical Society of America.
Bright-white light-emitting devices based on a single polymer exhibiting simultaneous blue, green, and red emissions
(2007-01-23)
Chuang, Chu-Ying
;
Shih, Ping-I
;
Chien, Chen-Han
;
Wu, Fang-Iy
;
Shu, Ching-Fong
We have developed efficient white-light-emitting polymers through the incorporation of low band gap green-light-emitting benzothiadiazole and red-light-emitting bisthiophenylbenzothiadiazole moieties into the backbone of a blue-light-emitting bipolar polyfluorene copolymer. Partial energy transfer from the blue-fluorescent polyfluorene backbone to the green- and red-fluorescent components resulted in individual emissions from the three emissive species. By carefully controlling the concentrations of the low-energy-emitting species in the resulting copolymers, the emission of white light, with contributions from each of the three primary colors, was achieved. Efficient polymer light-emitting devices prepared using these copolymers exhibited luminance efficiencies as high as 4.87 cd/A with color coordinates (0.37, 0.36) that were very close to the ideal CIE chromaticity coordinates for pure white light (0.33, 0.33). In addition, the color coordinates remained almost unchanged over a range of operating potentials. A mechanistic study suggested that energy transfer from the fluorene segments to the low band gap units, rather than charge trapping, was the main operating process involved in the electroluminescent process.
Investigation of InGaN/GaN light emitting diodes with nano-roughened surface by excimer laser etching method
(2007-01-25)
Huang, Hung-Wen
;
Kao, Chih-Chiang
;
Chu, Jung-Tang
;
Wang, Wei-Chih
;
Lu, Tien-Chang
The InGaN/GaN light emitting diodes (LEDs) with a nano-roughened top p-GaN surface fabricated by using Ni nano-masks and laser etching methods were demonstrated and analyzed. The experiment results observed the maximum light output power of the InGaN/GaN LED with a nano-roughened top p-GaN surface etched with the laser energy of 300 mJ/cm(2) was 1.55 times higher than that of a conventional LED, and the wall-plug efficiency was enhanced 68% at 20 mA. The series resistance of InGaN/GaN LED was reduced by 32% by the increase in the contact area of the nano-roughened surface. (c) 2006 Elsevier B.V. All rights reserved.
東埔之梅 ,漁人
(2007-01-27)
管管
Enhanced photoresponse of a metal-oxide-semiconductor photodetector with silicon nanocrystals embedded in the oxide layer
(2007-01-29)
Shieh, Jia-Min
;
Lai, Yi-Fan
;
Ni, Wei-Xin
;
Kuo, Hao-Chung
;
Fang, Chih-Yao
The authors report a two-terminal metal-oxide-semiconductor photodetector for which light is absorbed in a capping layer of silicon nanocrystals embedded in a mesoporous silica matrix on p-type silicon substrates. Operated at reverse bias, enhanced photoresponse from 300 to 700 nm was observed. The highest optoelectronic conversion efficiency is as high as 200%. The enhancements were explained by a transistorlike mechanism, in which the inversion layer acts as the emitter and trapped positive charges in the mesoporous dielectric layer assist carrier injection from the inversion layer to the contact, such that the primary photocurrent could be amplified. (c) 2007 American Institute of Physics.
Evanescent-field optical amplifiers and lasers
(2007-01-30)
Chen
;
Nan-Kuang
;
Chi
;
Sien
;
Tseng
An optical amplifier and a laser generator based on the fiber side-polished technology, having a high pumping efficiency, a low noise figure and a small footprint are provided in this application. The optical amplifier and the laser, which have a very long effective interaction length in conjunction with highly doped Erbium glass attached to its surface and an addition of a slanted fiber grating inscribed in the guiding core at the polished region can spatially separate the signal and pump power to simultaneously improve the pumping efficiency and optimize the penetrated depth of the signal evanescent-field. The spontaneous emission is kept from being amplified and therefore a high quality amplified signal is produced.
SODOCK: Swarm optimization for highly flexible protein-ligand docking
(2007-01-30)
Chen, Hung-Ming
;
Liu, Bo-Fu
;
Huang, Hui-Ling
;
Hwang, Shiow-Fen
;
Ho, Shinn-Ying
Protein-ligand docking can be formulated as a parameter optimization problem associated with an accurate scoring function, which aims to identify the translation, orientation, and conformation of a docked ligand with the lowest energy. The parameter optimization problem for highly flexible ligands with many rotatable bonds is more difficult than that for less flexible ligands using genetic algorithm (GA)-based approaches, due to the large numbers of parameters and high correlations among these parameters. This investigation presents a novel optimization algorithm SODOCK based on particle swarm optimization (PSO) for solving flexible protein-ligand docking problems. To improve efficiency and robustness of PSO, an efficient local search strategy is incorporated into SODOCK. The implementation of SODOCK adopts the environment and energy function of AutoDock 3.05. Computer simulation results reveal that SODOCK is superior to the Lamarckian genetic algorithm (LGA) of AutoDock. in terms of convergence performance, robustness, and obtained energy, especially for highly flexible ligands. The results also reveal that PSO is more suitable than the conventional GA in dealing with flexible docking problems with high correlations among parameters. This investigation also compared SODOCK with four state-of-the-art docking methods, namely GOLD 1.2, DOCK 4.0, FlexX 1.8, and LGA of AutoDock 3.05. SODOCK obtained the smallest RMSD in 19 of 37 cases. The average 2.29 angstrom of the 37 RMSD values of SODOCK was better than those of other docking programs, which were all above 3.0 angstrom. (C) 2006 Wiley Periodicals, Inc.
Two-dimensional densely packed DNA nanostructure derived from DNA complexation with a low-generation poly(amidoamine) dendrimer
(2007-01-30)
Su, Chun-Jen
;
Liu, Yi-Chun
;
Chen, Hsin-Lung
;
Li, Yen-Cheng
;
Lin, Hsien-Kuang
One of the keys for using deoxyribonucleic acid (DNA) as a nanomaterial relies on how the individual DNA chain can be aligned and how a multitude of DNA chains can be packed into ordered nanostructures. Here we present a simple method for constructing a 2-D densely packed DNA nanostructure using the electrostatic complex of DNA with a poly(amidoamine) (PAMAM) dendrimer of generation two. Ordered DNA arrays are formed by drop-casting an aqueous solution containing positively overcharged complexes onto mica followed by a prolonged incubation. During the incubation, the complexes tend to adsorb onto the negatively charged mica surface through electrostatic attraction. The rodlike complexes organize to form ordered arrays to increase the surface density of the adsorbed complexes and hence the attractive free energy of adsorption. The densely packed nanostructure obtained here is distinguished from the previously reported spheroid or toroid structure derived from DNA complexations with the higher-generation dendrimers.
Protein complexity, gene duplicability and gene dispensability in the yeast genome
(2007-01-31)
Lin, Yeong-Shin
;
Hwang, Jenn-Kang
;
Li, Wen-Hsiung
;
生物科技學系
;
Department of Biological Science and Technology
Using functional genomic and protein structural data we studied the effects of protein complexity (here defined as the number of subunit types in a protein) on gene dispensability and gene duplicability. We found that in terms of gene duplicability the major distinction in protein complexity is between hetero-complexes, each of which includes at least two different types of subunits (polypeptides), and homo-complexes, which include monomers and complexes that consist of only subunits of one polypeptide type. However, gene dispensability decreases only gradually as the number of subunit types in a protein complex increases. These observations suggest that the dosage balance hypothesis can explain well gene duplicability of complex proteins, but cannot completely explain the difference in dispensabilities between hetero-complex subunits. It is likely that knocking out a gene coding for a hetero-complex subunit would disrupt the function of the whole complex, so that the deletion effect on fitness would increase with protein complexity. We also found that multi-domain polypeptide genes are less dispensable but more duplicable than single-domain polypeptide genes. Duplicate genes derived from the whole genuine duplication event in yeast are more dispensable (except for ribosomal protein genes) than other duplicate genes. Further, we found that subunits of the same protein complex tend to have similar expression levels and similar effects of gene deletion on fitness. Finally, we estimated that in yeast the contribution of duplicate genes to genetic robustness against null mutation is similar to 9%, smaller than previously estimated. In yeast, protein complexity may serve as a better indicator of gene dispensability than do duplicate genes. (c) 2006 Elsevier B.V All rights reserved.
Covalently bonded polyhedral oligomeric silsesquioxane/polyimide nanocomposites and process for synthesizing the same
(2007-02-01)
Wei, Kuang-Hwa
;
Leu, Chyi-Ming
Polyhedral oligomeric silsesquioxane/polyimide nanocomposites with certain mechanical properties and low dielectric constant is synthesized by covalently tethering functionalized polyhedral oligomeric silsesquioxane molecules to polyimide. These nanocomposites appear to be self-assembled systems. A process for synthesizing said polyhedral oligomeric silsesquioxane/polyimide nanocomposites also is provided, comprising a step of forming porous type polyhedral oligomeric silsesquioxane, and a subsequent step of reacting with dianhydride or directly reacting with synthesized polyimide.
Three-dimensional thermoelectrical simulation in flip-chip solder joints with thick underbump metallizations during accelerated electromigration testing
(2007-02-01)
Liang, S. W.
;
Chang, Y. W.
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In flip-chip solder joints, thick Cu and Ni films have been used as under bump metallization (UBM) for Pb-free solders. In addition, electromigration has become a crucial reliability concern for fine-pitch flip-chip solder joints. In this paper, the three-dimensional (3-D) finite element method was employed to simulate the current-density and temperature distributions for the eutectic SnPb solder joints with 5-mu m Cu, 10-mu m Cu, 25-mu m Cu, and 25-mu m Ni UBMs. It was found that the thicker the UBM is the lower the maximum current density inside the solder. The maximum current density is 4.37 x 10(4) A/cm(2), 1.69 x 10(4) A/cm(2), 7.54 x 10(3) A/cm(2), and 1.34 x 10(4) A/cm(2), respectively, when the solder joints with the above four UBMs are stressed by 0.567 A. The solder joints with thick UBMs can effectively relieve the current crowding effect inside the solder. In addition, the joint with the thicker Cu UBM has a lower Joule heating effect in the solder. The joint with the 25-mu m Ni UBM has the highest Joule heating effect among the four models.
Evaluation research of polishing methods for large area diamond films produced by chemical vapor deposition
(2007-02-01)
Tsai, H. Y.
;
Ting, C. J.
;
Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
The current study compared several polishing techniques of chemical vapor deposition (CVD) diamond films. Although research on various diamond polishing techniques has been carried for years, some issues still need to be examined in order to facilitate application on large areas in a cost-efficient manner. In the present work, microwave plasma enhanced chemical vapor deposition (CVD) was used to obtain diamond films with full width half magnitude (FWHM) less than 10 wavenummbers at 1332 cm(-1) Raman peak. The diamond films were processed through mechanical polishing, chemical-assisted mechanical polishing, thermo-chemical polishing, excimer laser ablation, and catalytic reaction assisted grinding. A profilometer, an atomic force microscope, and a scanning electron microscope have been used to evaluate the surface morphology of diamond Films before and after polishing. The results obtained by using the above mentioned techniques were analyzed and compared. (c) 2006 Elsevier B.V. All rights reserved.
Laboratory astrophysics in Taiwan
(2007-02-01)
Lin, G. -L.
;
Liu, T. -C.
;
Huang, M. A.
;
Hwang, W-Y. P.
;
Chen, C. -C.
We report the development of laboratory astrophysics program in Taiwan. We begin with outlining Taiwan's participation in the FLASH collaboration for measuring the fluorescence yield using SLAC 28.5 GeV electron beam. We then report the domestic effort of studying cosmic ray shower properties using NSRRC 1.5 GeV electron beam.
Optimum power-saving method for power MOSFET width of DC-DC converters
(2007-02-01)
Chen, K.-H.
;
Chien, C.-C.
;
Hsu, C.-H.
;
Huang, L.-R.
;
電控工程研究所
An optimum power metal-oxide-semiconductor field effect transistor (MOSFET) width technique is proposed for enhancing the efficiency characteristics of switching DC-DC converters. By implementing a one-cycle buck DC-DC converter, it is demonstrated that the dynamic power MOSFET width controlling technique has a much improved power reduction whether the load current is light or heavy. The maximum efficiency of the buck converter is similar to 92% with a 3% efficiency improvement for the heavy load condition. The efficiency is further improved by similar to 16% for the light load condition as a result of the power reduction from the large power MOSFET transistors. Also proposed is a new error-correction loop circuit to enable a better load regulation than that of previous designs. Compared with the adaptive gate driver voltage technique, the optimum power MOSFET width can achieve a significant improvement in power saving. It is also superior to the low-voltage-swing MOSFET gate drive technique for switching DC-DC converters.
Effect of oxygen concentration on characteristics of NiOx-based resistance random access memory
(2007-02-01)
Lee, Ming-Daou
;
Ho, Chia-Hua
;
Lo, Chi-Kuen
;
Peng, Tai-Yen
;
Yao, Yeong-Der
The resistance bistability and the switching effect has been systematically studied in nickel oxide films with variable oxygen concentrations. Both the switching bias voltage and the resistance ratio of RESET to SET were found to be strongly concentration dependent. Meanwhile, the electrical characteristics can be exactly examined by an Schottky emission. By means of mathematical fitting, the resistance bistability seems to be related to the alternating of dielectric constant and the barrier height. Furthermore, the room temperature cycle endurance with a distinguishable operation window was found to exceed 800. This indicates that the nickel oxide has the potential to be a promising material on resistance random access memory.
Fast and versatile algorithm for nearest neighbor search based on a lower bound tree
(2007-02-01)
Chen, Yong-Sheng
;
Hung, Yi-Ping
;
Yen, Ting-Fang
;
Fuh, Chiou-Shann
;
資訊工程學系
In this paper, we present a fast and versatile algorithm which can rapidly perform a variety of nearest neighbor searches. Efficiency improvement is achieved by utilizing the distance lower bound to avoid the calculation of the distance itself if the lower bound is already larger than the global minimum distance. At the preprocessing stage, the proposed algorithm constructs a lower bound tree (LB-tree) by agglorneratively clustering all the sample points to be searched. Given a query point, the lower bound of its distance to each sample point can be calculated by using the internal node of the LB-tree. To reduce the amount of lower bounds actually calculated, the winner-update search strategy is used for traversing the tree. For further efficiency improvement, data transformation can be applied to the sample and the query points. In addition to finding the nearest neighbor, the proposed algorithm can also (i) provide the k-nearest neighbors progressively; (ii) find the nearest neighbors within a specified distance threshold; and (iii) identify neighbors whose distances to the query are sufficiently close to the minimum distance of the nearest neighbor. Our experiments have shown that the proposed algorithm can save substantial computation, particularly when the distance of the query point to its nearest neighbor is relatively small compared with its distance to most other samples (which is the case for many object recognition problems). (c) 2005 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.