Browsing by Author "Lee, Cheng-Chung"

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A recognition method in holographic data storage system by using structural similarity
(2013-01-01)
Chen, Yu-Ta
;
Ou-Yang, Mang
;
Lee, Cheng-Chung
;
電機工程學系
;
Department of Electrical and Computer Engineering
The holographic data storage system (HDSS) is a page-oriented storage system with advantages of great capacity and high speed. The page-oriented recording breaks the tradition of the optical storage of one-point recording. As the signal image is retrieved from the storage material in the HDSS, various noises influences the image and then the data retrieve will be difficultly from the image by using the thresholding method. For progressing on the thresholding method, a recognition method, based on the structural similarity, is proposed to replace the thresholding method in the HDSS. The recognition method is implemented that the image comparison between the receive image and reference image is performed by the structural similarity method to find the most similar reference image to the received image. In the experiment, by using recognition method, the bit error rate (BER) results in 26% decrease less than using the thresholding method in the HDSS. Owing to some strong effects, such as non-uniform intensity and strong speckle, still influencing on the received image, the recognition method is seemed to be slightly better than thresholding method. In the future, the strong effects would be reduced to improve the quality of the receive image and then the result of using the recognition method may be vastly better than the thresholding method.
An image based optical lens eccentric error inspection system
(2012)
Chen, Yung-Hsiang
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Hsieh, Yao-Fang
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Hsu, Chia-Wei
;
Ou-Yang, Mang
;
Lee, Cheng-Chung
In this study, we have presented the prototype of optical lens eccentric error inspection system based on image processing algorithms. The traditional inspection by using the transmission or reflection measurements is limited to the geometry and size of the lens. In this study, an image based inspection system has developed target on fast, accurate and low-cost to meet the need for lens eccentric error inspection.
Analysis of pentacene thin film transistors in different atmospheres
(2005)
Wang, Yu-Wu
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Cheng, Horng-Long
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Wang, Yi-Kai
;
Hu, Tang-Hsiang
;
Ho, Jia-Chong
This investigation addresses the electrical properties of pentacene-based thin film transistors in air, dry air and high vacuum. A potential barrier model was applied to explain the gate dependent field effect mobility behavior. The results show the trap density in air higher than that in a vacuum.
Biopsy Diagnosis of Oral Carcinoma by the Combination of Morphological and Spectral Methods Based on Embedded Relay Lens Microscopic Hyperspectral Imaging System
(2015-08-01)
Ou-Yang, Mang
;
Hsieh, Yao-Fang
;
Lee, Cheng-Chung
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
Cytopathological examination through biopsy is very important for carcinoma detection. The embedded relay lens microscopic hyperspectral imaging system (ERL-MHIS) provides a morphological image of a biopsy sample and the spectrum of each pixel in the image simultaneously. Based on the ERL-MHIS, this work develops morphological and spectral methods to diagnose oral carcinoma biopsy. In morphological discrimination, the fractal dimension method is applied to differentiate between normal and abnormal tissues. In spectral identification, normal and cancerous cells are distinguished using five methods. However, the spectra of normal and cancerous cells vary with patient. The diagnostic performances of the five methods are thus not ideal. Hence, the proposed cocktail approach is used to determine the effectiveness of the spectral methods in correlating with the sampling conditions. And then we use a combination of effective spectral methods according to the sample conditions for diagnosing a sample. A total of 68 biopsies from 34 patients are analyzed using the ERL-MHIS. The results demonstrate a sensitivity of 90 +/- 4.53 % and a specificity of 87.8 +/- 5.21 %. Furthermore, in our survey, this system is the first time utilized to study oral carcinoma biopsies.
Bottom-Contact n-Channel Organic Thin-Film Transistors with Naphthalene-Based Derivatives
(2009)
Kao, Chia-Chun
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Lin, Pang
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Chan, Li-Hsin
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Lee, Cheng-Chung
;
Ho, Jia-Chong
We investigated bottom-contact organic thin-film transistors based on n-benzyl naphthalene 1,4,5,8-tetracarboxylic diimides. The electrical characteristics were tested in both air and vacuum environments. n-Type semiconductors which are modified by fluorinated imide can be operated in ambient environment. The close packing of the fluorinated ester imide group leads to carrier mobility as high as 1.6x10(-2) cm(2) V(-1) s(-1). The short distance between each molecule can be found via a single-crystal structure.
Crowning Proteins: Modulating the Protein Surface Properties using Crown Ethers
(2014-11-24)
Lee, Cheng-Chung
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Maestre-Reyna, Manuel
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Hsu, Kai-Cheng
;
Wang, Hao-Ching
;
Liu, Chia-I
Crown ethers are small, cyclic polyethers that have found wide-spread use in phase-transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein-crown ether co-crystals grown in the presence of 18-crown-6. We then employed biophysical methods and molecular dynamics simulations to compare these complexes with the corresponding apoproteins and with similar complexes with ring-shaped low-molecular-weight polyethylene glycols. Our studies show that crown ethers can modify protein surface behavior dramatically by stabilizing either intra- or intermolecular interactions. Consequently, we propose that crown ethers can be used to modulate a wide variety of protein surface behaviors, such as oligomerization, domain-domain interactions, stabilization in organic solvents, and crystallization.
Determination of optimal converting point of color temperature conversion complied with ANSI C78. 377 for indoor solid-state lighting and display applications
(2012-08-27)
Hsieh, Yao-Fang
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Ou-Yang, Mang
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Huang, Ting-Wei
;
Lee, Cheng-Chung
;
電機資訊學士班
In recent years, displays and lighting require color temperature (CT) conversion function because observers have different preferences. This paper proposes effective methods to determine the optimal converting point of CT conversion for display and lighting application. For display application, the concepts of center of gravity and isotemperature line are applied to determine the optimal converting point. The maximal enhancement of luminance between the optimal and average is 18%. For lighting application, this paper proposes two methods to determine the optimal converting point in the CT quadrangle which complies with ANSI C78. 377. The enhancement of luminance in two CT modes (5700K and 6500K) are 14.2% and 23.6%, respectively. (C) 2012 Optical Society of America
Development of GaN-Based Vertical-Cavity Surface-Emitting Lasers
(2009-05-01)
Lu, Tien-Chang
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Chen, Jun-Rong
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Chen, Shih-Wei
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Kuo, Hao-Chung
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Kuo, Chien-Cheng
This paper reviews the fabrication technology and performance characteristics of optically pumped and electrically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs). The lasing action of optically pumped hybrid GaN-based VCSELs has been observed at room temperature due to the employment of high-quality and high-reflectivity AlN/GaN-based distributed Bragg reflectors in the VCSEL structure. Based on the device structure of the optically pumped hybrid GaN-based VCSELs, we further achieved the lasing action of electrically pumped GaN-based VCSELs under continuous-wave operation at 77 K. The laser has a threshold injection current of 1.4 mA and emits a blue wavelength at 462 nm together with a narrow linewidth of about 0.15 nm. The laser beam has a divergence angle of about 11.7 degrees with a polarization ratio of 80%. A very strong spontaneous coupling efficiency of 7.5 x 10(-2) was measured.
Estimation of spectral radiance on a tristimulus color sensor system illuminated under two light sources
(2015-01-01)
Mang, Ou-Yang
;
Hsieh, Yao-Fang
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Lee, Cheng-Chung
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電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
The tristimulus color sensor system, a trichromatic camera, is developed to estimate the spectral radiance of objects. However, since the spectral sensitivity of the system does not match the Commission International de l\'Eclairage (CIE) 1931 color matching function, it yields inaccurate colorimetric and spectral information. This work proposes methods using two light sources for estimating accurate spectral radiance and verifies that the accuracy achieved using these two illuminant methods exceeds that achieved using single illuminant methods. The two illuminant methods successfully reduce the mean color difference in CIELAB from 31.24 to 0.8 and provide a spectral accuracy of 0.0103. Furthermore, a tristimulus color sensor system is developed to verify the performance of these methods. (C) 2015 Elsevier GmbH. All rights reserved.
Finite conjugate embedded relay lens hyperspectral imaging system (ERL-HIS)
(2011-11-20)
Hsieh, Yao-Fang
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Ou-Yang, Mang
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Lee, Cheng-Chung
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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
We present a novel embedded relay lens hyperspectral imaging system (ERL-HIS) with high spectral resolution (nominal spectral resolution of 2.8 nm) and spatial resolution (30 mu m x 8 mu m) that transfers the scanning plane to an additional imaging plane through the internal relay lens so as to alleviate all outside moving parts for the scanning mechanism used in the traditional HIS, where image scanning is achieved by the relative movement between the object and hyperspectrometer. The ERL-HIS also enables high-speed scanning and can attach to a variety of optical modules for versatile applications. Here, we also demonstrate an application of the proposed ERL-HIS attached to a microscopic system for observing autofluorescent images of sliced cancer tissue samples. (C) 2011 Optical Society of America
High-performance bottom-contact devices based on an air-stable n-type organic semiconductor N,N-bis (4-trifluoromethoxybenzyl)-1,4,5,8-naphthalene-tetracarboxylic di-imide
(2007-05-21)
Kao, Chia-Chun
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Lin, Pang
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Lee, Cheng-Chung
;
Wang, Yi-Kai
;
Ho, Jia-Chong
N,N-bis(4-trifluoromethoxybenzyl)-1,4,5,8-naphthalene-tetracarboxylic di-imide was applied to organic semiconductors for bottom-contact thin-film transistors. The carrier mobility was 1.6x10(-2) cm(2) V-1 s(-1), the threshold voltage (V-T) was +5.5 V, and the on/off current ratio was 8.6x10(5). Devices without any further surface treatments were tested in an ambient environment. The threshold voltage shift (Delta V-T) was verified by gate bias stress measurements. A prototype compound, N,N-bis(4-trifluoromethylbenzyl)naphthalene-1,4,5,8-tetracarboxylic di-imide, shows direct correlation to the bottom-contact device with the varied molecular structure. (c) 2007 American Institute of Physics.
Improvement of bit error rate and page alignment in the holographic data storage system by using the structural similarity method
(2012-06-01)
Chen, Yu-Ta
;
Ou-Yang, Mang
;
Lee, Cheng-Chung
;
電機工程學系
;
Department of Electrical and Computer Engineering
Although widely recognized as a promising candidate for the next generation of data storage devices, holographic data storage systems (HDSS) incur adverse effects such as noise, misalignment, and aberration. Therefore, based on the structural similarity (SSIM) concept, this work presents a more accurate locating approach than the gray level weighting method (GLWM). Three case studies demonstrate the effectiveness of the proposed approach. Case 1 focuses on achieving a high performance of a Fourier lens in HDSS, Cases 2 and 3 replace the Fourier lens with a normal lens to decrease the quality of the HDSS, and Case 3 demonstrates the feasibility of a defocus system in the worst-case scenario. Moreover, the bit error rate (BER) is evaluated in several average matrices extended from the located position. Experimental results demonstrate that the proposed SSIM method renders a more accurate centering and a lower BER, lower BER of 2 dB than those of the GLWM in Cases 1 and 2, and BER of 1.5 dB in Case 3. (C) 2012 Optical Society of America
Influence of polymer dielectric surface energy on thin-film transistor performance of solution-processed triethylsilylethynyl anthradithiophene (TES-ADT)
(2012-02-01)
Chen, Liang-Hsiang
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Lin, Pang
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Kim, Choongik
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Chen, Ming-Chou
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Huang, Peng-Yi
This study investigates the correlation between surface energy of polymer dielectrics and the film morphology, microstructure, and thin-film transistor performance of solution-processed 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) films. The low surface energy polyimide (PI) dielectric induced large grains with strong X-ray reflections for spin-cast TES-ADT films in comparison to high surface energy poly(4-vinyl phenol) (PVP) dielectric. Furthermore, thin-film transistors based on spin-cast TES-ADT films on PI dielectric exhibited enhanced electrical performance, small hysteresis, and high stability under bias stress with carrier mobility as high as 0.43 cm(2)/Vs and a current on/off ratio of 10(7). (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Large vacuum Rabi splitting in ZnO-based hybrid microcavities observed at room temperature
(2009-02-09)
Chen, Jun-Rong
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Lu, Tien-Chang
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Wu, Yung-Chi
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Lin, Shiang-Chi
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Liu, Wei-Rein
Wide-band gap ZnO semiconductors are attractive materials for the investigation of microcavity exciton polaritons due to the large exciton binding energy and oscillator strength. We report the growth and characterization of bulk ZnO-based hybrid microcavity. The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based hybrid microcavity structure, which consists of 30 pair epitaxially grown AlN/AlGaN distributed Bragg reflector (DBR) on the bottom side of the 3/2 lambda thick ZnO cavity and 9 pair SiO(2)/HfO(2) DBR as the top mirror. The cavity quality factor is about 221. The experimental results show good agreement with theoretically calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be about 58 meV in the ZnO-based hybrid microcavity.
Large Vacuum Rabi Splitting in ZnO-Based Microcavities
(2009)
Chen, Jun-Rong
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Lu, Tien-Chang
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Wu, Yung-Chi
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Lin, Shiang-Chi
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Liu, Wei-Rein
We report the growth and characterization of bulk ZnO-based hybrid microcavity (MC). The phenomenon of strong exciton-photon coupling at room temperature has been observed in the ZnO-based MC. The cavity quality factor is 221. The experimental results show good agreement with calculated exciton-polariton dispersion curves based on transfer matrix method. From the theoretical and experimental exciton-polariton dispersion curves with two different cavity-exciton detuning values, the large vacuum Rabi splitting is estimated to be 58 meV in the ZnO-based MC.
Measurement of binocular disparity in polarized based stereoscopic display by using digital camera
(2013-06-01)
Chen, Yu-Ta
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Hsu, Shau-Wei
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Pong, Bao-Jen
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Ou-Yang, Mang
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Lee, Cheng-Chung
This work presents an image displacement measurement by using a box pattern and the edge spread function analysis in the polarized based stereoscopic displays. The measurement determines to identify three factors (i.e., box size, image displacement, and spatial frequency response (SFR)) from the box patterns. The polarized based stereoscopic displays might sacrifice pixels for producing 3D images, which might produce errors in the image displacement and then affect the depth perception indirectly. Based on the measurement, the errors can be quantified by using the three factors. Owing to the light leakage distorting the edge spread function to obtain an inferior SFR, exactly how light leakage affects the edge spread function can be resolved on the basis of the SFR results, especially at a frequency (1/display pixel) of 1.9 in the case of the horizontal displacement. Light leakage also induces the error of the box height in even and odd intervals of the vertical displacements more than 2pixels and 0.5pixels, respectively. The image displacement measurement provides a simple and comprehensive means of evaluating the optical characteristics, disparity, and sharpness of the stereoscopic displays, via the three factors.
Observation of Polariton Dispersions for ZnO Microcavities in Strong Couple Regime
(2010)
Chen, Jun-Rong
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Lu, Tien-Chang
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Wu, Yung-Chi
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Lin, Shiang-Chi
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Liu, Wei-Rein
Characteristics of ZnO-based MCs with vacuum Rabi splitting of 72 meV are demonstrated. It is found that only the LPBs can be observed in ZnO MCs since the Rabi splitting pushes UPBs into scattering absorption.
Perylenetetracarboxylic di-imide-based bottom-contact devices: A study on two kinds of source/drain electrodes, ITO and MoW
(2009-01-01)
Kao, Chia-Chun
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Lin, Pang
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Shen, Yu-Yuan
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Yan, Jing-Yi
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Ho, Jia-Chong
High-performance bottom-contact devices based on an air-stable n-type organic semiconductor N,N-bis(4-trifluoromethoxybenzyl)-perylene-3,4,9,10-tetracarboxylic di-imide, were fabricated, and the effects of crystal packing on indium tin oxide and molybdenum-tungsten alloy were shown in two different electric characteristics. The estimated work function of indium tin oxide and molybdenum-tungsten alloy were 4.7 and 5.0eV. The calculated lowest unoccupied molecular orbital energy level of the organic material was 3.7eV. Transistors with indium tin oxide bottom electrodes exhibited a high mobility of 3.37 x 10(2) cm(2) V(-1) s(1), an on/off current ratio of 6.5 x 10(5) and threshold voltage of-4.0 V. (C) 2008 Elsevier B.V All rights reserved.
Polyimide/Ta(2)O(5) nanocomposite gate insulators for enhanced organic thin-film transistor performance
(2011-08-01)
Chen, Liang-Hsiang
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Lin, Pang
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Ho, Jia-Chong
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Lee, Cheng-Chung
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Kim, Choongik
This study reports the preparation and characterization of polyimide/Ta(2)O(5) nanocomposite films as insulators for organic thin-film transistors (OTFTs). The degree of imidization, thermal, electrical, and surface properties of the nanocomposite films were characterized as a function of Ta(2)O(5) precursor contents. The nanocomposite films, with controlled/comparable insulator electrical characteristics and surface properties, have been found to enhance dielectric constant compared to pristine polyimide films, which resulted in improved pentacene TFT performance by a factor of 2-3 with carrier mobility values as high as 0.38 cm(2)/Vs. (C) 2011 Elsevier B.V. All rights reserved.
Polyimide/Ta2O5 nanocomposite gate insulators for enhanced organic thin-film transistor performance
(2011-08-01)
Chen, Liang-Hsiang
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Lin, Pang
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Ho, Jia-Chong
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Lee, Cheng-Chung
;
Kim, Choongik
This study reports the preparation and characterization of polyimide/Ta2O5 nanocomposite films as insulators for organic thin-film transistors (OTFTs). The degree of imidization, thermal, electrical, and surface properties of the nanocomposite films were characterized as a function of Ta2O5 precursor contents. The nanocomposite films, with controlled/comparable insulator electrical characteristics and surface properties, have been found to enhance dielectric constant compared to pristine polyimide films, which resulted in improved pentacene TFT performance by a factor of 2-3 with carrier mobility values as high as 0.38 cm(2)/Vs. (C) 2011 Elsevier B.V. All rights reserved.