Browsing by Issue Date, starting with "2008-12"

Now showing 1 - 20 of 54054

Breaking concept boundaries to enhance creative potential: Using integrated concept maps for conceptual self-awareness
(2008-12-01)
Kao, Gloria Yi-Ming
;
Lin, Sunny S. J.
;
Sun, Chuen-Tsai
;
教育研究所
;
資訊工程學系
The authors address the role of computer support for building conceptual self-awareness-that is, enabling students to think outside of concept boundaries in hope of enhancing creative potential. Based on meta-cognition theory, we developed an integrated concept mapping system (ICMSys) to improve users' conceptual self-awareness in addition to applying concept mapping techniques in traditional learning scenarios. Since the ICMSys accommodates different perspectives, selected ideas made by peers are retained with the help of integrated concept map (ICMap) representations used as stimuli for reflective thinking. Results from a case study with 32 information management undergraduates indicate: (a) increased levels of conceptual self-awareness, (b) evidence of conceptual improvement in the students' redrawn concept maps, (c) that Map viewing frequency exerted a positive impact on level of conceptual self-awareness, and (d) a significant correlation between level of conceptual self-awareness in redrawn personal concept maps and actual conceptual changes as determined by three experts. We describe student perceptions of the ICMSys in terms of comprehension practicality and conceptual self-awareness, and give suggestions for future research. (C) 2008 Elsevier Ltd. All rights reserved.
Human capital externality and chaotic equilibrium dynamics
(2008-12-01)
Chen, Hung-Ju
;
Li, Ming-Chia
;
應用數學系
;
Department of Applied Mathematics
This study develops a two-period overlapping generations model in which adults undertake educational investment decisions oil behalf of young agents. In addition to educational investment, we argue that the accumulation of human capital is also dependent upon the externality from average human capital within the economy. In a departure from the previous literature in this area, we assume that there is a reduction in the overall productivity of human capital accumulation brought about by human capital externality, and show that complicated dynamics will emerge under this circumstance. In addition to displaying the chaotic dynamics in the sense of Li and Yorke, we also verify the existence of Devaney's chaos and Smale's chaos.
Characteristics of HfO(2)/Poly-Si Interfacial Layer on CMOS LTPS-TFTs With HfO(2) Gate Dielectric and O(2) Plasma Surface Treatment
(2008-12-01)
Ma, Ming-Wen
;
Chiang, Tsung-Yu
;
Wu, Woei-Cherng
;
Chao, Tien-Sheng
;
Lei, Tan-Fu
In this paper, high-performance complementary-metal-oxide-semiconductor low-temperature polycrystalline-silicon thin-film transistors (CMOS LTPS-TFTs) with HfO(2) gate dielectric are fabricated on one wafer for the first time. Low threshold voltage and excellent subthreshold swing can be achieved simultaneously for N- and P-channel LTPS-TFTs without hydrogenation. In addition, the impacts of the HfO(2)/poly-Si interfacial layer on N- and P-channel LTPS-TFTs are also specified. In order to enhance the characteristics of HfO(2) LTPS-TFT further, oxygen plasma surface treatment is employed to improve the interface quality and passivate the defects of channel grain boundaries, thus increasing the carrier mobility and reducing the phonon scattering. The CMOS LTPS-TFTs with HfO(2) gate dielectric and oxygen plasma treatment would be suitable for the application of system-on-panel.
An RFID-Based Manufacturing Control Framework for Loosely Coupled Distributed Manufacturing System Supporting Mass Customization
(2008-12-01)
Chen, Ruey-Shun
;
Tsai, Yung-Shun
;
Tu, Arthur
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
In this study we propose a Manufacturing control framework based on radio-frequency identification (RFID) technology and a distributed information system to construct a mass-customization production process in a loosely coupled shop-floor control environment. On the basis of this framework. we developed RFID middleware and in integrated information system for tracking and controlling the manufacturing process flow. A bicycle Manufacturer was used to demonstrate the prototype system. The findings of this study were that the proposed framework can improve the visibility and traceability of the manufacturing process as well as enhance process quality control and real-time production pedigree access. Using this framework, an enterprise can easily integrate an RFID-based system into its manufacturing environment to facilitate mass customization and a just-in-time production model.
Current status of resistive nonvolatile memories
(2008-12-01)
Lin, Chih-Yang
;
Liu, Chih-Yi
;
Lin, Chun-Chieh
;
Tseng, T. Y.
;
電子工程學系及電子研究所
Several emerging nonvolatile memories (NVMs) such as ferroelectric memory, magnetoresistive rams and ovonic universal memory are being developed for possible applications. Resistive random access memory (RRAM) is another interesting competitor in the class of NVMs. The RRAM is based on a large change in electrical resistance when the memory film is exposed to voltage or current pulses, and can keep high or low resistance states without any power. The ideal RRAM Should have the superior properties of reversible switching, long retention tune, multilevel switching, simple structure, small size, and low operating voltage. Perovskite oxides, transition metal oxides, and molecular materials were found to have resistive memory properties. This presentation reviews the ongoing research and development activities on future resistance NVMs technologies incorporating these new memory materials. The possible basic mechanisms for their bistable resistance switching are described. The effect of processing, composition, and structure on the properties of resistive memory materials and consequently the devices are discussed.
Effects of annealing temperature on the resistance switching behavior of CaCu(3)Ti(4)O(12) films
(2008-12-01)
Shen, Yu-Shu
;
Chiou, Bi-Shiou
;
Ho, Chia-Cheng
;
電子工程學系及電子研究所
;
Innovative Packaging Research Center
In this study, a novel material CaCu(3)Ti(4)O(12) (CCTO), for resistance random access memory application, was prepared by sol-gel method and annealed at various temperatures. The crystallinity and microstructure of CCTO film, improve as annealing temperature increases. The CCTO films annealed at 800 degrees C and above endure more switching cycles (> 1000) and exhibit a small degradation of the resistance ratio between the high resistance state and the low resistance state than those annealed at 700 degrees C do. The correlation between resistance switching behaviors and film microstructure is discussed. (C) 2008 Elsevier B.V. All rights reserved.
Investigation of InGaN/GaN power chip light emitting diodes with TiO(2)/SiO(2) omnidirectional reflector
(2008-12-01)
Huang, H. W.
;
Lin, C. H.
;
Yu, C. C.
;
Lee, B. D.
;
Kuo, H. C.
Enhancements of light extraction of GaN-based power chip (PC) LEDs with and without rough surface on p-GaN and TiO(2)/SiO(2) omnidirectional reflector (ODR) on the bottom are presented. Motivated by phosphor-conversion white light applications, the peak-emitting wavelength of our studied PC LEDs is chosen to be 455 nm and the fabricated ODR is designed for the same wavelength regime. At a driving current of 350 mA and a chip size of 1 mm x 1 mm on a TO-can package, the light output power of the PC LED with ODR on the bottom and pit type of rough surface on p-GaN is enhanced by 67% when compared with the same device without ODR and rough surface. Furthermore, by examining the radiation patterns, the PC LED with the ODR and rough surface shows stronger enhancement around the vertical direction. Our results provide promising potential to increase output powers of commercial light emitting devices, especially for white light applications.
A COMPACT CASCADE QUADRUPLET BANDPASS FILTER WITH LOW TEMPERATURE COFIRED CERAMIC TECHNOLOGY
(2008-12-01)
Lin, Hong-Ching
;
Lin, Pang
;
Tang, Ching-Wen
;
Wang, Sea-Fue
;
材料科學與工程學系
In this article, a compact cascade quadruplet bandpass filter has been proposed. This bandpass filter has been realized with the semilumped method and can generate a pair of transmission zeros at the two sides of passband by using the nonadjacent cross coupling. The analysis and design procedures are provided in this article. To miniaturize the size of the circuit and improve its performance, multilayered structure and the low-temperature cofired ceramic technology are employed to design and fabricate the filter. Measurement results agree well with the electromagnetic simulation, which can validate the proposed structure. (c) 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3218-3220, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23910
Enhancement of subband effective mass in Ag/Ge(111) thin film quantum wells
(2008-12-01)
Tang, S. -J.
;
Chang, Wen-Kai
;
Chiu, Yu-Mei
;
Chen, Hsin-Yi
;
Cheng, Cheng-Maw
Subband dispersions of quantum-well states in Ag films on Ge(111) have been determined by angle-resolved photoemission. The effective masses of the subbands at the zone center increase substantially for decreasing film thicknesses. This peculiar behavior is attributed to a kinetic constraint for standing-wave formation governed by a momentum-dependent phase-shift function. No evidence is found for in-plane electron localization within the confined geometry.
Positive Bias Temperature Instability (PBTI) Characteristics of Contact-Etch-Stop-Layer-Induced Local-Tensile-Strained HfO(2) nMOSFET
(2008-12-01)
Wu, Woei-Cherng
;
Chao, Tien-Sheng
;
Chiu, Te-Hsin
;
Wang, Jer-Chyi
;
Lai, Chao-Sung
The positive bias temperature instability (PBTI) characteristics of contact-etch-stop-layer (CESL)-strained HfO(2) nMOSFET are thoroughly investigated. For the first time, the effects of CESL on an HfO(2) dielectric are investigated for PBTI characteristics. A roughly 50% reduction Of V(TH) shift can be achieved for the 300-nm CESL HfO(2) nMOSFET after 1000-s PBTI stressing without obvious HfO(2)/Si interface degradation, as demonstrated by the negligible charge pumping current increase (< 4%). In addition, the HfO(2) film of CESL devices has a deeper trapping level (0.83 eV), indicating that most of the shallow traps (0.75 eV) in as-deposited HfO(2) film can be eliminated for CESL devices.
A Computationally Efficient Method for Large Subcarrier Assignment and Bit Allocation Problem of Multiuser OFDM System
(2008-12-01)
Lin, Shin-Yeu
;
Huang, Jung-Shou
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose a computationally efficient method to solve the large dimension Adaptive Subcarrier Assignment and Bit Allocation (ASABA) problem of multiuser orthogonal frequency division multiplexing system. Our algorithm consists of three Ordinal Optimization (00) stages to find a good enough solution to the considered problem. First of all, we reformulate the considered problem to separate it into subcarrier assignment and bit allocation problem such that the objective function of a feasible subcarrier assignment pattern is the corresponding optimal bit allocation for minimizing the total consumed power. Then in the first stage, we develop an approximate objective function to evaluate the performance of a subcarrier assignment pattern and use a genetic algorithm to search through the huge solution space and select s best subcarrier assignment patterns based on the approximate objective values. In the second stage, we employ an off-line trained artificial neural network to estimate the objective values of the s subcarrier assignment patterns obtained in stage I and select the I best patterns. In the third stage, we use the exact objective function to evaluate the I subcarrier assignment patterns obtained in stage 2, and the best one associated with the corresponding optimal bit allocation is the good enough solution that we seek. We apply our algorithm to numerous cases of large-dimension ASABA problems and compare the results with those obtained by four existing algorithms. The test results show that our algorithm is the best in both aspects of solution quality and computational efficiency.
A 2.4-5.4-GHz Wide Tuning-Range CMOS Reconfigurable Low-Noise Amplifier
(2008-12-01)
Fu, Chang-Tsung
;
Ko, Chun-Lin
;
Kuo, Chien-Nan
;
Juang, Ying-Zong
;
電子工程學系及電子研究所
A 2.4-5.4-GHz CMOS reconfigurable low-noise amplifier (LNA) is designed. It consists of two stages: a broadband input stage for a steady input matching and noise performance, and a reconfigurable band-selective stage which provides a wide-range frequency tuning from 2.4 to 5.4 GHz and a 12-dB stepped gain with linearity adjustment. The frequency tuning is conducted by a multitapped switching inductor and varactors. Careful design of the switching inductor achieves consistent performance among frequency configurations. The stepped gain and linearity adjustment are provided by a size-switchable transistor with a variable biasing. Fabricated in 0.13 mu m CMOS technology this LNA exhibits performance including up to 25 dB power gain, 2.2-3.1 dB noise figure and less than 5 mW power consumption under 1 V power supply.
High-Frequency Characteristic Fluctuations of Nano-MOSFET Circuit Induced by Random Dopants
(2008-12-01)
Li, Yiming
;
Hwang, Chih-Hong
;
電信工程研究所
;
Institute of Communications Engineering
As the dimension of semiconductor device shrunk into nanometer scale (nanoscale), characteristic fluctuation is more pronounced, and become crucial for circuit design. In this paper, discrete-dopant-induced characteristic fluctuation of 16-nm-gate metal-oxide-semiconductor field effect transistors (MOSFET) circuit under high-frequency regime is quantitatively studied. The circuit gain, the 3 dB bandwidth and the unity-gain bandwidth of the tested nanoscale transistor circuit are calculated concurrently capturing the discrete-dopant-number- and discrete-dopant-position-induced fluctuations in the large-scale statistically sound "atomistic" device/circuit coupled simulation. For the 16-nm-gate MOSFET circuit, the number of discrete dopants, varying from zero to 14, may result in 5.7% variation of the circuit gain, 14.1% variation of the 3 dB bandwidth, and 10.4% variation of the unity-gain bandwidth. To suppress the high-frequency characteristic fluctuations, an improved doping distribution along the longitudinal diffusion direction from the MOSFET's surface to substrate is further performed to examine the associated fluctuation. The improved vertical doping profile with less dopants locating near surface of channel effectively reduces the fluctuations of the circuit gain, the 3 dB bandwidth and the unity-gain bandwidth dramatically. Compared with the original doping profile, the reduction is 32.3%, 19.4% and 51.8%, respectively. This study provides an insight into random-dopant-induced intrinsic high-frequency characteristic fluctuations and verifies the potential fluctuation suppression technique on high-frequency characteristic fluctuations of nanoscale transistor circuit.
A layer-integrated approach for shallow water free-surface flow computation
(2008-12-01)
Hung, Meng-Chi
;
Hsieh, Te-Yung
;
Tsai, Tung-Lin
;
Yang, Jinn-Chuang
;
土木工程學系
A novel semi-three-dimensional (semi-3D) layer-integrated approach was proposed in this study for the shallow water free-surface flow computation. A quadratic shape function proposed to approximate the velocity distribution in the layer ensures the continuity of velocities and shear stresses at interfaces. To discretize the governing equations, the finite volume formulation with staggered grid is used. As the two-dimensional (2D) sub-model for locating the free surface is not needed in this approach, the computational time consumption has been dramatically reduced. The model was verified through the wind-induced circulation in a closed basin by comparing the velocity profiles to the analytical solution. The formation of the velocity profiles due to change of viscosity distribution and the evolution process of water surface slope were also investigated. Further, the eddy viscosity is estimated by a function related to discharge, water depth, and Manning's n under the assumption of parabolic distribution of longitudinal velocity along the vertical direction for open channel flows. Two designed hypothetical cases were conducted to examine the proposed eddy viscosity relation and to demonstrate the capabilities of the proposed model. Copyright (C) 2007 John Wiley & Sons, Ltd.
A Decoupling Technique for Increasing the Port Isolation Between Two Strongly Coupled Antennas
(2008-12-01)
Chen, Shin-Chang
;
Wang, Yu-Shin
;
Chun, Shyh-Jong
;
電信工程研究所
;
Institute of Communications Engineering
A compact decoupling network for enhancing the port isolation between two closely spaced antennas is proposed in this paper. In the network, we first connect two transmission lines (TLs) individually to the input ports of two strongly coupled antennas. The length of the TLs is designed so that the trans-admittance between ports changes from a complex one at the antenna inputs to a pure imaginary one. A shunt reactive component is then attached in between the TL ends to cancel the resultant imaginary trans-admittance. Finally, a simple lumped-element circuit is added to each port for input impedance matching. The even-odd mode analysis is adopted to investigate the currents excited on the antennas for predicting the radiation pattern of the two-element antenna array. Two examples of printed antennas at 2.45 GHz are tackled by using the proposed decoupling structure. The measurement results agree quite well with the simulation ones. High antenna isolation and good input return loss are simultaneously achieved in both cases, which demonstrates the feasibility of the structure. The decoupled antenna array in each example radiates, as prediction, toward different but complementary directions when the input power is fed in turn to the two input ports. The array efficiency is estimated better than 75% in each example. This pattern diversity effect is helpful for reducing the channel correlation in a multiple-input multiple-output (MIMO) communication system.
Alkanethiol-based single-molecule transistors
(2008-12-01)
Ma, Chun-Lan
;
Nghiem, Diu
;
Chen, Yu-Chang
;
電子物理學系
;
Department of Electrophysics
We have investigated the transport properties of alkanethiol molecules in the two-terminal and three-terminal junctions by using first-principles approaches. We observe that states around the Fermi levels are introduced in the amino-substituted butanethiol junction. It leads to a sharp increase in the current, which is credited to the resonant tunneling. The current-voltage characteristics suggest that the amino-substituted butanethiol molecular junction may be a promising candidate for field-effect transistors.
Theoretical study on S-1(B-1(3u)) state electronic structure and absorption spectrum of pyrazine
(2008-12-01)
He RongXing
;
Zhu ChaoYuan
;
Chin Chih-Hao
;
Lin Sheng-Hsien
;
應用化學系分子科學碩博班
Making use of a set of quantum chemistry methods, the harmonic potential surfaces of the ground state (S-0((1)A(g))) and the first (S-1(B-1(3u))) excited state of pyrazine are investigated, and the electronic structures of the two states are characterized. In the present study, the conventional quantum mechanical method, taking account of the Born-Oppenheimer adiabatic approximation, is adopted to simulate the absorption spectrum of S-1(B-1(3u)) state of pyrazine. The assignment of main vibronic transitions is made for S-1(B-1(3u)) state. It is found that the spectral profile is mainly described by the Franck-Condon progression of totally symmetric mode v(6a). For the five totally symmetric modes, the present calculations show that the frequency differences between the ground and the S-1(B-1(3u)) state are small. Therefore the displaced harmonic oscillator approximation along with Franck-Condon transition is used to simulate S-1(B-1(3u)) absorption spectra. The distortion effect due to the so-called quadratic coupling is demonstrated to be unimportant for the absorption spectrum, except the coupling mode v(10a). The calculated S-1(B-1(3u)) absorption spectrum is in reasonable agreement with the experimental spectra.
Charge storage characteristics of Mo nanocrystal dependence on Mo oxide reduction
(2008-12-01)
Lin, Chao-Cheng
;
Chang, Ting-
;
Tu, Chun-Hao
;
Chen, Wei-Ren
;
Hu, Chih-Wei
An oxygen incorporated Mo silicide was explored to form the Mo nanocrystals after rapid thermal annealing. Transmission electron microscopy showed the nanocrystals embedded in SiO(x). Charge storage characteristics of Mo nanocrystals influenced by the Mo oxide and the surrounding oxide were investigated through x-ray photoelectron spectroscopy and the electrical measurement. X-ray photoelectron spectra analyses revealed the redox reaction in the oxygen incorporated Mo silicide layer after rapid thermal annealing. The memory window and retention were improved due to reduction in Mo oxide.
【第十一屆校友會會務】財務委員會財務收支報告
(國立陽明大學牙醫校友會, 2008-12)
余宗坤
Segmentation of cDNA microarray images by kernel density estimation
(2008-12-01)
Chen, Tai-Been
;
Lu, Henry Horng-Shing
;
Lee, Yun-Shien
;
Lan, Hsiu-Jen
;
統計學研究所
The segmentation of cDNA microarray spots is essential in analyzing the intensities of microarray images for biological and medical investigation. In this work, nonparametric methods using kernel density estimation are applied to segment two-channel cDNA microarray images. This approach groups pixels into both a foreground and a background. The segmentation performance of this model is tested and evaluated with reference to 16 microarray data. In particular, spike genes with various contents are spotted in a microarray to examine and evaluate the accuracy of the segmentation results. Duplicated design is implemented to evaluate the accuracy of the model. The results of this study demonstrate that this method can cluster pixels and estimate statistics regarding spots with high accuracy. (c) 2008 Elsevier Inc. All rights reserved.