Browsing by Author "Lin, Chih-Wei"

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Atomic layer deposition of epitaxial ZnO on GaN and YSZ
(2007-01-01)
Lin, Chih-Wei
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Ke, Dong-Jie
;
Chao, Yen-Cheng
;
Chang, Li
;
Liang, Mei-Hui
ZnO thin films were epitaxially grown by atomic layer deposition on both of GaN/c-sapphire and yttria-stabilized zirconia (YSZ) substrates for comparison. X-ray diffraction, cross-sectional transmission electron microscopy (TEM) and photoluminescence (PL) measurements show that epitaxial ZnO films have better structural qualities and optical properties on GaN than on YSZ, whereas atomic force microscopy (AFM) shows that the surface of ZnO films on YSZ is smoother than on GaN. From the ZnO thickness measured by TEM, the growth rate of ZnO on GaN is about one (0 0 0 2) monolayer per cycle, which is roughly four times of that on YSZ. (c) 2006 Elsevier B.V. All rights reserved.
Digital Primary-Side Sensing and PFC Control of a Flyback Converter
(2011)
Lin, Chih-Wei
;
Tzou, Ying-Yu
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電控工程研究所
;
Institute of Electrical and Control Engineering
Primary-side sensing (PSS) technique can be used for the output voltage or current regulation of a flyback converter by employing an auxiliary winding for the indirect detection of output voltage and conduction period of the output rectifier diode. However, errors in the estimation of output voltage or current may be induced by the voltage drop of the secondary diode, secondary leakage inductance, secondary winding resistance, and measurement error due to limited bandwidth of the sensing circuits. In this paper, a sampling instant modulation technique is developed to reduce the sensing error in primary-side sensing of flyback converters. This new PSS sampling technique is then implemented for the power factor correction (PFC) of a flyback converter. A multi-mode control strategy can improve sampling accuracy at the zero-crossing of the rectified input voltage. Experimental results are shown to verify the feasibility of PSS technique realized with digital control technique.
Digital Voltage Control of Boost CRM PFC AC/DC Converters with TRIAC Phase Control Dimmer
(2012)
Lin, Chih-Wei
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Tzou, Ying-Yu
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電機工程學系
;
Department of Electrical and Computer Engineering
This paper presents a digital voltage control scheme for boost critical conduction mode (CRM) power-factor-correction (PFC) AC/DC converters with TRIAC phase control dimmer to use in the lighting equipment ex. LED or fluorescent lamp. The TRIAC is a standard type of dimmer and work fine with resistive load such as ordinary Tungsten filament light bulb (incandescent lamp), however, for non-resistive lighting sources, a well-designed AC-DC converter must be designed to provide good power quality as well as wide linear non-flickering dimming control range. A variable PFC output voltage modulation method is proposed to enhance the dimming control range. The TRIAC dimmer will cause switching oscillations due to the PFC input filter, a damper circuit is designed to minimize this effect. The proposed control scheme has been verified by using simulation software PSIM in applications to a 50 W prototype of boost CRM PFC AC/DC converter with TRIAC phase control dimmer. Simulation and experimental results are given to illustrate the feasibility of the proposed control scheme.
Discovering role-based virtual knowledge flows for organizational knowledge support
(2013-04-01)
Liu, Duen-Ren
;
Lin, Chih-Wei
;
Chen, Hui-Fang
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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 knowledge-intensive work environments, workers need task-relevant knowledge and documents to support the execution of tasks. A knowledge flow (KF) represents an individual's or group's knowledge-needs and referencing behavior of codified knowledge during the performance of organizational tasks. Through knowledge flows, organizations can provide workers with task-relevant knowledge to satisfy their knowledge-needs. In teamwork environments, knowledge workers with different roles and task functions usually have diverse knowledge-needs, but conventional KF models cannot satisfy such needs. In a previous work, we proposed a novel concept and theoretical model called Knowledge Flow View (KFV). Based on workers diverse knowledge-needs, the KFV model abstracts knowledge nodes of partial KFs and generates virtual knowledge nodes through a knowledge concept generalization procedure. However, the KFV model did not consider the diverse knowledge-needs of workers who play different roles in a team. Therefore, in this work, we propose a role-based KFV model that discovers role-based virtual knowledge flows to satisfy the knowledge-needs of different roles. First, we analyze the level of knowledge required by workers to fulfill various roles. Then, we develop role-based knowledge flow abstraction methods that generate appropriate virtual knowledge nodes to provide sufficient knowledge for each role. The proposed role-based ITV model enhances the efficiency of KF usage, as well as the effectiveness of knowledge sharing and knowledge support in organizations. (c) 2013 Elsevier B.V. All rights reserved.
From electrostatic precipitation to nanoparticle generation
(2012-09-01)
Lin, Chih-Wei
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Huang, Sheng-Hsiu
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Kuo, Yu-Mei
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Chang, Kuang-Nan
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Wu, Chong-Sin
This work demonstrated that an electrostatic precipitator (ESP), originally designed for dust collection, could become a nanoparticle generator under specific operating conditions. A lab-scale wire-plate positive ESP was built for measuring aerosol penetration and generation rate. The carrier air was filtered by activated charcoal, silica gel and HEPA filters to remove potential contaminants. The data, obtained in both power-on and power-off modes, were utilized to calculate penetration and generation rate of aerosol. The results showed that air temperature appeared to have a strong effect on ESP nanoparticle generation. At temperature above 37 C and flow rate below 9 L/min, the nanoparticle penetration of ESP exceeded 100%, indicating that the ESP was generating aerosol particles. Sputtering on the corona discharger appeared to be the key mechanism of aerosol generation. The ozone concentration increased with increasing corona current. The ESP reached a maximum number concentration at the electric field strength of 4.8 kV/cm when the air flow and temperature were fixed at 6 L/min and 40 C, respectively. The particle size ranged from 5 to 40 nm, with a mode around 12 nm. Elementary components of the discharge wire were detected on the filter samples collected downstream the ESP and ground plates, indicating that nanoparticles were generated from the discharge wire. (C) 2012 Elsevier Ltd. All rights reserved.
From electrostatic precipitation to nanoparticle generation (vol 51, pg 57, 2012)
(2012-10-01)
Lin, Chih-Wei
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Huang, Sheng-Hsiu
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Kuo, Yu-Mei
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Chang, Kuang-Nan
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Wu, Chong-Sin
Growth and structural characterization of ZnO on Y2O3/YSZ by pulsed laser deposition
(2008-03-15)
Lin, Chih-Wei
;
Ho, Yen-Teng
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Chang, Li
;
材料科學與工程學系
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Department of Materials Science and Engineering
Pulsed laser deposition was used to form epitaxial Y2O3 buffer layers on yttria-stabilized zirconia (YSZ) (111) substrates, followed by formation of epitaxial ZnO. Structural characterization by X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) shows that Y2O(3) has high-quality crystalline characteristics with a smooth (111) surface, providing a good buffer for deposition of ZnO films on YSZ. For ZnO deposition, a two-step growth process had been adopted, which consisted of low-temperature nucleation and high-temperature growth. ZnO films on Y2O3/YSZ have good structural qualities in c-axis orientation with smooth surfaces. Electron diffraction patterns show an orientation relationship of [2 (1) over bar(1) over bar0](ZnO)//[0 (1) over bar1](Y2O3) and (0002)(ZnO)//(222)(Y2O3). High-resolution TEM clearly reveals that both the interfaces of ZnO/Y2O3 and Y2O3/YSZ are flat without the formation of any interlayers. (C) 2007 Elsevier B.V. All rights reserved.
Growth of epitaxial ZnO thin film on yttria-stabilized zirconia single-crystal substrate
(2007-01-01)
Chao, Yen-Cheng
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Lin, Chih-Wei
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Ke, Dong-Jie
;
Wu, Yue-Han
;
Chen, Hou-Guang
ZnO growth on yttria-stabilized zirconia (YSZ) (I 1 1) single-crystal substrate has been carried out by metalorganic chemical vapor deposition (MOCVD). High-quality epitaxial ZnO has been evidenced by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cross-sectional TEM from all deposited films reveals that the interface between ZnO and YSZ is atomically flat, and orientation relationship is deduced to be [1 (1) over bar 100](ZnO//)[11 (2) over bar](YSZ,) (2 (1) over bar(1) over bar0)(ZnO)//[001](YSZ) and (0 0 0 2)(ZnO)//(111)(YSZ). It has been found that surface roughness increases with the substrate temperature in the range of 500-700 degrees C. The growth rate also varies with the temperature. (c) 2006 Elsevier B.V. All rights reserved.
Growth of nonpolar (11(2)over-bar0) ZnO films on LaAlO(3) (001) substrates
(2008-09-22)
Ho, Yen-Teng
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Wang, Wei-Lin
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Peng, Chun-Yen
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Liang, Mei-Hui
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Tian, Jr-Sheng
Nonpolar (11 (2) over bar0) ZnO films were grown on LaAlO(3) (001) single crystal substrates at temperature from 300 to 750 S C by pulsed laser deposition method. The films were examined using x-ray diffraction, reflection high energy electron diffraction, and photoluminescence measurements for the crystallinity. The surface morphology of ZnO films from atomic force microscopy exhibits L-shaped domains. Cross-sectional transmission electron microscopy with selected area diffraction reveals two types of a-plane ZnO domains perpendicular to each other with in-plane orientation relationships of [0001](ZnO)
Growth of zinc oxide thin films on Y2O3/Si substrates by chemical vapor deposition
(2005-02-15)
Lin, Chih-Wei
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Cheng, Tsan-Yao
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Chang, Li
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Juang, Jenh-Yih
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電子物理學系
Epitaxial ZnO was deposited on Si(1 1 1) substrate by atmospheric pressure metal-organic chemical vapor deposition (MOCVD) at 500 degrees C. A Y2O3 buffer layer in epitaxy with Si substrate has successfully suppressed the Si oxidation before ZnO deposition. The Y2O3 film was grown by pulsed laser deposition (PLD) on Si(1 1 1) substrate at 800 degrees C. Also, ZnO was deposited by PLD for comparison with MOCVD. X-ray diffraction and cross-sectional transmission electron microscopy was used to characterize microstructures of the ZnO films and their interfaces with Y2O3. The result shows ZnO(0 0 0 2) parallel to Y2O3(1 1 1). With the increase of the deposition time, the grain morphology of ZnO thin films evolved from flat structure to columnar structure. Most of the columnar ZnO grains are c-axis oriented perpendicular to the interface. (C) 2004 Elsevier B. V. All rights reserved.
Modeling the knowledge-flow view for collaborative knowledge support
(2012-07-01)
Liu, Duen-Ren
;
Lin, Chih-Wei
;
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 knowledge-based organizations, workers need task-relevant knowledge and documents to support their task performance. A knowledge flow (KF) represents the flow of an individual's or group members' knowledge-needs and the referencing sequence of documents in the performance of tasks. Through knowledge flows, organizations can provide task-relevant knowledge to workers to fulfill their knowledge-needs. Nevertheless, in a collaborative environment, workers usually have different knowledge-needs in accordance with their individual task functions. Conventional KF models do not provide workers with the different views of a knowledge flow that they require to meet these knowledge-needs. Several researchers have investigated KF models but they did not address the concept of the knowledge-flow view (KFV). This study proposes a theoretical model of the KFV using innovative methods. Basically, a KFV is a virtual knowledge flow derived from a base knowledge flow that abstracts knowledge concepts for individual workers based on their knowledge-needs. The KFV model in this study builds knowledge-flow views by abstracting knowledge nodes in a base knowledge flow to generate corresponding virtual knowledge nodes through an order-preserving approach and a knowledge concept generalization mechanism. The knowledge-flow views not only fulfill workers' different knowledge-needs but also facilitate knowledge support in teamwork. (C) 2012 Elsevier B.V. All rights reserved.
Self-Pulsation in Two-Section Laser with an air gap
(2012)
Lin, Chien-Chung
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Lin, Chih-Wei
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Chien, Chen-Yu
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Kuo, Hao-Chung
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光電系統研究所
This study explores the optical field distribution of 1.55 mu m InGaAsP distributed feedback Laser with an air gap in the middle section. The optical field distribution was analyzed by different depth and width of an air gap. From the calculation, we could observe how the gap affect the coupling of the optical field into the other cavity. The percentage of the coupling is a crucial factor to the injection-locking operation. Both effective index model and commercial software were used to predict this coupling.
THE CHEMICAL STAIN INSPECTION OF POLYSILICON SOLAR CELL WAFER BY THE FUZZY THEORY METHOD
(2013-08-01)
Lin, Chern-Sheng
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Lin, Chih-Wei
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Yang, Shih-Wei
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Lin, Shir-Kuan
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Chiu, Chuang-Chien
This study proposed an automatic optical inspection (AOI) technique to improve the inspection of chemical stains on solar wafers. Poly-silicon solar cell wafers were inspected for chemical stains, and the inspection was rapid and stable. The system used a laser-reflection-point-based AOI method for solar wafer chemical stain inspection. Based on the fuzzy theory, the image binarization algorithm could efficiently filter irrelevant image information, and the back-propagation method was also utilized to determine if the image was stained. The inspection algorithm integrated fuzzy theory and the back-propagation method in order to shorten the comparison time and quickly find the target. The experiment proved that the validity of the proposed method could achieve a recognition rate of 98% from among 1000 images.
Tunable Microwave Generation by Photonic Integrated Distributed Feedback Lasers
(2012)
Lin, Chien-Chung
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Lin, Chih-Wei
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Chien, Chen-Yu
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Kuo, Hao-Chung
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光電系統研究所
We demonstrated a novel air/semiconductor mirrors integrated distributed feedback lasers by focused ion beam technology. When two DFB lasers are powered together, an injection-locking operation can produce strong microwave signals up to 25.5 GHz.