Browsing by Author "Tsai, CY"

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A fully all-planar integrated Ka-band FSK transceiver module
(2001)
Lee, CJ
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Hung, TP
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Lin, SC
;
Wu, HS
;
Tsai, CY
An open RFIC (Radio Frequency Integrated Circuit) architecture employing ACSS (Advanced Coplanar Strips System) guiding technology is presented in this paper. This approach can integrate all the RF front-end components in one module using conventional PCB (printed circuit board) fabrication process. A 10 Mb/s FSK signal is upconverted to 30.18 GHz and 30.28 GHz and broadcasted through a cone-shaped antenna at power level of 10 dBm. The received signal is directly converted to baseband by even harmonic quadrature mixer, which shows a great isolation of 30 dB between RF and LO signal. The measured waveforms of the reported transceiver demonstrate the potential of constructing the wireless system with all-planar integrated circuits.
Advances of MPEG scalable video coding standard
(2005)
Peng, WH
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Tsai, CY
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Chiang, TH
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Hang, HM
;
交大名義發表
To support clients with diverse capabilities, the MPEG committee is defining a novel scalable video coding (SVC) framework that can simultaneously support multiple spatial, temporal and SNR resolutions under the constraints of low complexity and low delay. To fulfill the requirements, two major approaches have been considered as the potential technologies. One is the wavelet-based scheme and the other is the scalable extension of MPEG-4 AVC/H.264. This paper aims to give a brief overview for the latest advances of these technologies.
Applications of microtube array on transtlective liquid crystal displays for backlight efficiency enhancement
(2004-12-01)
Yang, YS
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Huang, YP
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Shieh, HPD
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Tsai, MC
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Tsai, CY
A novel transflective liquid crystal display (LCD) with a microtube array structure to make the most effective use of backlight was demonstrated. By redefining the area ratio of transmissive and reflective regions, high light efficiency in both transmissive and reflective subpixels can be attained. Based on the principle of light collection, a simulation model was established to characterize the features and optimize the microtube array structure. Furthermore, a typical TFT-LCD process was utilized to fabricate the optimized structure. A prototype microtube array was fabricated, and the measured enhancement of backlight utilization efficiency can be as high as a factor of 1.81.
Applying electric-magnetic-electric (EME) composite metal strips to reduce the size of patch antennas
(2001)
Tsai, CY
;
Tzuang, CKC
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電信工程研究所
;
Institute of Communications Engineering
This paper presents a novel technology to reduce the size of microstrip patch antennas. Utilizing this recently developed periodic structure (EME metal strips), we can increase the slow-wave factor of microstrip lines. This benefit can help us to reduce the size of patch antennas. According to our experimental results, the resonant length and area of the EME patch can be reduced to be 76% and 57% when compared with the conventional one.
Carrier depletion by defects levels in relaxed In0.2Ga0.8As/GaAs quantum-well Schottky diodes
(2000-02-01)
Chen, JF
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Wang, PY
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Wang, JS
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Tsai, CY
;
Chen, NC
An increase in leakage current accompanied by a drastic carrier depletion is found for InGaAs/GaAs Schottky diodes when the InGaAs thickness is larger than its critical thickness. Due to drastic carrier depletion, free-carrier concentration around the InGaAs region for relaxed samples cannot be obtained from capacitance-voltage data but from resistance-capacitance time constant effect observed in capacitance-frequency measurement. A trap at 0.33 to 0.49 eV is observed for relaxed samples by deep-level transient spectroscopy. The resistance caused by carrier depletion has an activation energy close to that of the trap, supporting that the carrier depletion is caused by capture from the trap. (C) 2000 American Institute of Physics. [S0021-8979(00)00603-4].
Color reproduction of twist nematic LCD by polynomial regression applied in primary-invariance model
(1999)
Tsai, CY
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Liaw, MJ
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Shieh, HPD
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光電工程學系
;
Department of Photonics
As primary-shifts on LCDs is non-negligible, primary-invariance model, widely used to characterize the color reproduction on CRT monitors, can not be applied well on LCDs. To obtain average color difference of less than 3 Delta E-uv* for LCDs, primary-invariance forward model should be modified by at least a 3x9 regression analysis matrix. In backward model, polynomial regression method can transfer data in both RGB and XXZ domains. However, only in XYZ domain, desired colors can be reproduced sufficiently.
Compositional dependence of the oxidation behavior of SiC-ZrO2-mullite composites
(1999)
Tsai, CY
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Lin, CC
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材料科學與工程學系
;
Department of Materials Science and Engineering
The oxidation of hot-pressed SiC-particle (SiCp)/zirconia/mullite composites with various zirconia contents, exposed in air isothermally at 1000 and 1200 degrees C respectively for up to 500 hours, was investigated. A clear critical volume fraction of zirconia existed for exposure at either 1000 or 1200 degrees C. The oxidation rate increased dramatically beyond 20 vol% ZrO2,. Additionally, oxidation modes of SiC/zirconia/mullite composites were classified on the basis of the gradient of the silica layer (formed on individual SiC particles) thickness versus depth curve. When the volume fraction of ZrO2, was below a threshold limit, the composites exhibited Mode I behavior; otherwise, Mode II was observed. For composites with zirconia content above the threshold limit, the formation of zircon, as a result of the reaction between zirconia and oxidation product (i.e. silica), might change the oxidation behavior from Mode II to Mode I.
Demosaicing: Heterogeneity-projection hard-decision adaptive interpolation using spectral-spatial correlation
(2006-01-01)
Tsai, CY
;
Song, KT
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電控工程研究所
;
Institute of Electrical and Control Engineering
A novel heterogeneity-projection hard-decision adaptive interpolation (HPHD-AI) algorithm is proposed in this paper for color reproduction from Bayer mosaic images. The proposed algorithm aims to estimate the optimal interpolation direction and perform hard-decision interpolation, in which the decision is made before interpolation. To do so, a new heterogeneity-projection scheme based on spectral-spatial correlation is proposed to decide the best interpolation direction from the original mosaic image directly. Exploiting the proposed heterogeneity-projection scheme, a hard-decision rule can be designed easily to perform the interpolation. We have compared this technique with three recently proposed demosaicing techniques: Lu's, Gunturk's and Li's methods, by utilizing twenty-five natural images from Kodak PhotoCD. The experimental results show that HPHD-AI outperforms all of them in both PSNR values and S-CIELab Delta E-ab* measures.
Demosaicing: Heterogeneity-projection hard-decision adaptive interpolation using spectral-spatial correlation - art. no. 606906
(2006)
Tsai, CY
;
Song, KT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A novel heterogeneity-projection hard-decision adaptive interpolation (HPHD-AI) algorithm is proposed in this paper for color reproduction from Bayer mosaic images. The proposed algorithm aims to estimate the optimal interpolation direction and perform hard-decision interpolation, in which the decision is made before interpolation. To do so, a new heterogeneity-projection scheme based on spectral-spatial correlation is proposed to decide the best interpolation direction from the original mosaic image directly. Exploiting the proposed heterogeneity-projection scheme, a hard-decision rule can be designed easily to perform the interpolation. We have compared this technique with three recently proposed demosaicing techniques: Lu's, Gunturk's and Li's methods, by utilizing twenty-five natural images from Kodak PhotoCD. The experimental results show that HPHD-AI outperforms all of them in both PSNR values and S-CIELab Delta E-ab* measures.
Dependence of oxidation modes on zirconia content in silicon carbide zirconia mullite composites
(1998-12-01)
Tsai, CY
;
Lin, C
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材料科學與工程學系
;
Department of Materials Science and Engineering
Two basic oxidation modes of silicon carbide/zirconial mullite (SiC/ZrO2/mullite) composites were defined based on the plotted curve of the gradient of the silica (SiO2) layer thickness (formed on individual SiC particles) versus depth. Mode I, where oxygen diffusivity was much slower in the matrix than in the SiO2 layer, exhibited a relatively large gradient and limited oxidation depth. Mode II, where oxygen diffusivity was much faster in the matrix than in the SiO2 layer, displayed a relatively small gradient and an extensive oxidation depth. When the volume fraction of ZrO2 was below a threshold limit, the composites exhibited Mode I behavior; otherwise, Mode II behavior mas observed. For composites with a ZrO2 content above the threshold limit, the formation of zircon (ZrSiO4), as a result of the reaction between ZrO2 and the oxidation product (i.e., SiO2), might change the oxidation behavior from Mode II to Mode I.
Effect of zirconia content on the oxidation behavior of silicon carbide/zirconia/mullite composites
(1998-09-01)
Tsai, CY
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Lin, CC
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Zangvil, A
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Li, AK
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材料科學與工程學系
The oxidation of hot-pressed SiC-particle (SiCp)/zirconia (ZrO2)/mullite composites with various ZrO2 contents, exposed in air isothermally at 1000 degrees and 1200 degrees C for up to 500 h, was investigated; an emphasis was placed on the effects of the ZrO2 content on the oxidation behavior. A clear critical volume fraction of ZrO2 existed for exposures at either 1000 degrees or 1200 degrees C: the oxidation rate increased dramatically at ZrO2 contents of >20 vol%. The sharp transition in the oxidation rate due to the variation of ZrO2 content could be explained by the percolation theory, when applied to the oxygen diffusivity in a randomly distributed two-phase medium. Morphologically, the composites with ZrO2 contents greater than the critical value showed a large oxidation zone, whereas the composites with ZrO2 contents less than the critical value revealed a much-thinner oxidation zone. The results also indicated that the formation of zircon (ZrSiO4) at 1200 degrees C, through the reaction between ZrO2 and the oxide product, could reduce the oxidation rate of the composite.
Enhanced motion estimation for interframe wavelet video coding
(2004)
Tsai, CY
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Hsu, HK
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Huang, HC
;
Hang, HM
;
Wu, GZ
An enhanced motion estimation scheme is incorporated into the interframe wavelet coding architecture in this paper. Interframe wavelet coding has the advantage of SNR, temporal, and spatial scalability, and is a potential candidate for the on-going MPEG-21 scalable video coding standard. Motion-compensated temporal Filtering (MCTF) is one of its essential components. Therefore, motion estimation plays an important role in deciding the coding performance. In this paper, we modified the motion estimation syntax/scheme originally specified in the MPEG Advanced Video Coding (AVC) and use it in the interframe wavelet structure. Besides, the techniques of I-block, bi-directional motion estimation, lambda-value adjustment and motion information partitioning are employed. Simulation results show very promising performance particularly on subjective quality.
Fast parking control of mobile robots: A motion planning approach with experimental validation
(2004-09-01)
Lee, TC
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Tsai, CY
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Song, KT
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a solution to the general parking problem of nonholonomic mobile robots based on motion planning and tracking controller design. A new global tracking controller is first proposed to achieve global uniformly asymptotic stability and local exponential convergence. The parking problem is then transformed into a tracking one by adding a redesigned virtual trajectory to the original trajectory, thus guaranteeing practical stability with exponential convergence. Further improvement in parking performance is obtained through. linearization and pole-placement methods. One feature of our approach is that fast convergence in parking and tracking can be treated at the same time without switching between two controllers. Moreover, a tuning function is used to enhance parking performance. With the proposed framework, various tracking controllers given in the literature can be adopted to handle parking problems. The effectiveness of the proposed methods is verified by several interesting experiments including parallel parking and back-into-garage parking.
FGS-based video streaming test bed for MPEG-21 universal multimedia access with digital item adaptation
(2003)
Wang, CN
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Tsai, CY
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Lin, HC
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Chaung, HC
;
Lin, YC
It is a challenging problem to stream real-time video over heterogeneous networks with time-varying channel conditions and devices with different capabilities. In this paper, we present an FGS based unicast video streaming test bed, which is now being considered by the MPEG-4/21 committee as a reference test bed. The proposed system supports resource adaptation delivery of MPEG-21 DIA scheme which leads to a more strict evaluation methodology according to the MPEG committee specified common test conditions for scalable video coding. It provides easy control of media delivery with duplicable network conditions. To provide the best quality of service for each client, we propose relevant rate control, error protection, and transmission approaches in the content server, network interface, and clients, respectively.
Observation of carrier depletion and emission effects on capacitance dispersion in relaxed In0.2Ga0.8As/GaAs quantum wells
(1999-10-18)
Chen, JF
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Wang, PY
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Tsai, CY
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Wang, JS
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Chen, NC
Strong changes in capacitance over frequency are found for highly relaxed In0.2Ga0.8As/GaAs quantum well. The high-frequency dispersion is explained by a resistance-capacitance time constant effect due to the existence of a high resistive layer while the low-frequency dispersion is due to carrier emission from traps. The high-resistance layer is created by carrier depletion when InGaAs thickness increases beyond the critical thickness. Excellent agreement is found between the data from capacitance-frequency spectra and deep-level transient spectroscopy, permitting us to conclude that both the carrier depletion and emission effects observed in capacitance-frequency spectra are due to the existence of an acceptor trap at 0.33 eV. This trap is generated when the InGaAs thickness is beyond its critical thickness and is due to defect states associated with misfit dislocations. (C) 1999 American Institute of Physics. [S0003-6951(99)02342-6].
Periodic stepped-impedance ring resonator (PSIRR) bandpass filter with a miniaturized area and desirable upper stopband characteristics
(2006-03-01)
Kuo, JT
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Tsai, CY
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電信工程研究所
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Institute of Communications Engineering
A periodic stepped-impedance ring resonator (PSIRR) is proposed to design dual-mode bandpass filters with a miniaturized area and desirable upper stopband characteristics. Design parameters of a PSIRR include impedance ratio R of the hi-Z to low-Z sections, their lengths, and number of impedance steps 2N. The resonant characteristics of PSIRRs with various N and R values are investigated by both the transmission-line theory and electromagnetic simulation. Proper choice of the above parameters leads to an optimal reduction of circuit area and extension of upper rejection bandwidth. Two extra transmission zeros exist in the upper stopband and are tunable via changing the arm lengths of the line-to-ring coupling structure. Realized by the standard microstrip technology, the dual-mode PSIRR bandpass filter has not only the first spurious response at higher than 3.7 x the passband frequency, but also, an area reduction of better than 60% against a conventional ring filter. Experimental results of several fabricated circuits validate the analysis and theoretical prediction.
Real-time implementation of H.263+ using TI TMS320C6201 digital signal processor
(2003)
Shih, KT
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Tsai, CY
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Hang, HM
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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
In this paper, we use a digital signal processor (DSP) to implement a real-time H.263+ codec. We use fast algorithms to reduce the codec computational complexity. Furthermore, the C programs are modified to take advantages of the DSP architecture and its C compiler features to reduce the on-chip memory and to increase the processing speed. In addition, a simple but effective rate-control algorithm is implemented to maintain the target bit rate. We can encode about 20 QCIF frames/second using one TI DSP. And the average decoding speed is about 26 QCIF frames/second.
Visual tracking control of a mobile robot using a new model in image plane
(2005)
Tsai, CY
;
Song, KT
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電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a novel visual tracking model in image plane for autonomous mobile robots. Based on this control model, a single visual tracking controller is proposed for both static and moving objects in a two-dimensional plane. In this design, the mobile robot is equipped with a fixed camera for environment detection. The visual feedback is used to control the robot pose for tracking a moving object of interest. A novel state space representation of the camera-object visual interaction model fully defined in the image plane is first derived, a closed-loop stabilizing control law is then designed. The visual tracking control scheme achieves exponential convergence of the closed-loop visual tracking system through pole-placement method. Simulation results verify the effectiveness of the proposed control scheme, both in terms of tracking performance and system convergence.