Browsing by Author "Lee, Chi-Hung"

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A New Technology of Scrape-Applied Method for the Manufacturing of MEA of Fuel-Cell System
(2008)
Wu, Shinn-Dar
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Lee, Chi-Hung
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Chou, Chang-Pin
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Wang, Yen-Zen
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機械工程學系
The technical transfer from electrode of lithium battery to MEA of fuel cells (including PEMFC and DMFC) were discussed in this study. There are three common methods for the manufacturing of lithium battery electrode; such as roller-applied method, scrape-applied method and spurt-applied method. The first two methods are the most commonly used method. This study was focused on the development of new scrape-applied equipment for lithium battery electrode. This new method was tested by measure the weight and thickness of dry electrode. The stability and reproducibility on electrode fabrication were also conducted by systematical data analysis. The results can offer an important basis to the future research on academic and commercial field.
Astigmatic diffractive optical element for swing-arm-type optical pickup head
(2009-07-01)
Lee, Chi-Hung
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Chiu, Yi
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Shieh, Han-Ping D.
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電控工程研究所
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光電工程學系
Based on a finite-conjugate objective lens with numerical aperture of 0.62 for a 650-nm wavelength, an optical pickup head composed of a multifunction beamsplitter and a diffractive optical element is designed be used in a swing-arm-type optical pickup head. The diffractive optical element is a lens with an elliptical four-level phase profile to provide both focusing and astigmatism. It is also designed with the goal to simplify the overall optical configuration and provide linear characteristics for the focus error signal. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI:10.1117/1.3158944]
Binary-phase micrograting and polarization beamsplitter for free-space micro-optical pickups
(2007-08-01)
Lee, Chi-Hung
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Chiu, Yi
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Shieh, Han-Ping D.
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電控工程研究所
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光電工程學系
A pop-up binary-phase micrograting and a pop-up micro polarization beamsplitter, for potential use in micro-optical pickups, have been realized on a single silicon chip using a two-layer polysilicon and one-layer silicon nitride micromachining process. In the case of the micrograting, a diffraction efficiency ratio between 4 and 10 can be achieved provided that the duty cycle is between 0.4 and 0.6 and the depth between 455 and 485 nm, respectively. For a grating designed for a diffraction ratio of 7, the measured ratio is 8.31. The polarization beamsplitter is a silicon nitride thin film placed at the Brewster angle. The transmittance of the TM mode was measured to be more than 98.5%, while the reflectance of the TE mode was 21.4%. (c) 2007 Society of Photo-Optical Instrumentation Engineers.
Color separation system with angularly positioned light source module for pixelized backlighting
(2010-01-18)
Chen, Po-Chou
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Lin, Hui-Hsiung
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Chen, Cheng-Huan
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Lee, Chi-Hung
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Lu, Mao-Hong
A color-separation system that angularly positions color LEDs to produce color separation and a lens array to focus this light onto the pixels is proposed. The LED rays from different incident angles are mapped into corresponding sub-pixel positions to efficiently display color image, which can be used to replace the absorbing color filter in the conventional liquid crystal layer. In this paper, the prototype backlight has been designed, fabricated and characterized. The measurement results of this module showed that a gain factor of transmission efficiency three times more than that of conventional color filters efficiency improvement and a larger color gamut are expected. (C)2010 Optical Society of America
Confined martensitic phase transformation kinetics and lattice dynamics in Ni-Co-Fe-Ga shape memory alloys
(2016-05-15)
Cong, Daoyong
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Rule, Kirrily Clair
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Li, Wen-Hsien
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Lee, Chi-Hung
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Zhang, Qinghua
Insights into the phase transformation kinetics and lattice dynamics associated with the newly discovered confined martensitic transformation are of great significance to the in-depth understanding of the phase transformation behavior responsible for the rich new physical phenomena in shape memory alloys and could shed light on the design of novel multifunctional properties through tuning the confined martensitic transformation. Here, we employ in-situ elastic and inelastic neutron scattering techniques to reveal the characteristics of transformation kinetics and lattice dynamics in two Ni55-xCoxFe18Ga27 magnetic shape memory alloys with x = 5.5 and 6.5. With a remarkable difference in transformation temperature, these two alloys show similar vibrational properties. Phonon softening of the TA(2)[xi xi 0] phonon branch, manifested as a dip at xi similar to 033 on the phonon dispersion curves, was disclosed by inelastic neutron scattering experiments; but this phonon softening is much less pronounced than that observed in stoichiometric Ni2MnGa or near-stoichiometric Ni-Fe-Ga Heusler alloys. The dispersion curves for the TA(2)[xi xi 0] phonon branch are only weakly dependent on temperature. The less pronounced phonon softening and very weak temperature dependence of the phonon dispersion curves could be attributed to the martensitic transformation which is confined by local inhomogeneities. This confined martensitic transformation shows a sluggish nature and occurs in a broad temperature range. The sluggish transformation was evidenced by the existence of residual austenite at low temperatures far below the martensitic transformation start temperature. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Design of virtual keyboard using blink control method for the severely disabled
(2013-08-01)
Yang, Shih-Wei
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Lin, Chern-Sheng
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Lin, Shir-Kuan
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Lee, Chi-Hung
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電控工程研究所
In this paper, a human-machine interface with the concept of "blink control" is proposed. The human-machine interface is applied to an assistive device, namely "blink scanning keyboard", which is designed specifically for the severely physical disabled and people suffering from motor neuron diseases or severe cerebral palsy. The pseudo electromyography (EMG) signal of blinking eyes could be acquired by wearing a Bluetooth headset with one sensor on the forehead and the other three on the left ear of the user. Through a conscious blink, a clear and immediate variation will be formed in the pseudo EMG signal from the users' forehead. The occurrence of this variation in pseudo EMG signal could be detected and filtered by the algorithms proposed in this paper, acting like a trigger to activate the functions integrated in the scanning keyboard. The severely physical and visual disabled then can operate the proposed design by simply blinking their eyes, thus communicating with outside world. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
Dye-less color filter fabricated by roll-to-roll imprinting for liquid crystal display applications
(2009-07-20)
Lin, Hui-Hsiung
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Lee, Chi-Hung
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Lu, Mao-Hong
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光電工程學系
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Department of Photonics
A diffractive grating is promising for color separation to effectively replace conventional absorptive dye color filter in liquid crystal displays. In this paper, we demonstrated a color separation module consisting of an aspheric-lenticular lens array and a blazed grating to substitute for the dye color filter. Each component was designed to match the recent fabrication ability of our roll-to-roll imprinting. The measurement results of a prototype module showed a gain factor of transmission efficiency three times more than that of conventional color filters. (C) 2009 Optical Society of America
Effect of Bridging Groups on Sulfonated Poly(imide-Siloxane) for Application in Proton Exchange Membrane
(2010-04-01)
Lee, Chi-Hung
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Chen, Jia-Ru
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Shiu, Hung-Wei
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Ho, Ko-Shan
;
Wu, Shinn-Dar
A series of six-membered sulfonated poly(imide-siloxane)s (SPIs) was synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), aminopropyl-terminated polydimethylsiloxane (PDMS) 2,2-benzidinedisulfonic acid (BDSA), as the sulfonation target diamine groups, and various nonsulfonated diamine monomers behaving as bridging groups. The structure-property relationship of SPI-SXx membranes is discussed in detail according to the chemical structure of the various nonsulfonated diamines of the SPI-SXx membranes from the viewpoints of proton conductivity, ion exchange capacity (IEC), and membrane properties (water uptake and membrane swelling) at equal PDMS content SPI-SXx. The PDMS was introduced to enhance the proton conductivity and water uptake attributed from the high flexibility of the siloxane segments. The conductivity and water uptake of angled SPI-SXm and oxydianiline-based SPI-SX membranes (SPI-SXO) are greater than those prepared from diaminodiphenylmethane-based SPI-SX membranes (SPI-SXD) at a given IEC. These differences resulted from the increased number of entanglements of the SPI-SXx membrane. The SPI-SXD showed almost isotropically dimensional changes with the increase in water uptake, and the volume were slightly smaller than those estimated from the additivity rule. Free volume in the SPI-SXx increased with the increase in bulky irregular packing in nonsulfonated segments, which augmented the water uptake and, in turn, the conductivity of the polymer. With the increase in temperature, conductivity increased more rapidly in SPI-SXx than in Nafion 117. Microscopic analyses revealed that these smaller (<10 nm) and well-dispersed hydrophilic domains contribute to better proton conducting properties. The new sulfonated poly(imide-siloxane) s have proved to be a possible candidate as the polymer electrolyte membrane for polymer electrolyte fuel cells (PEFCs) and direct methanol fuel cells (DMFCs). [DOI: 10.1115/1.3200906]
Eliminating spherical aberration by gradient-indexed lenses: Geometrical derivation and manufacturing methods
(2007-11-01)
Lee, Cheng Chung
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Hsu, Jia-Cherng
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Lee, Chi-Hung
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光電工程學系
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Department of Photonics
Gradient-indexed lenses have been used to eliminate spherical aberration. The design is usually executed using numerical methods. We contribute a new way called concentric gradient-indexed lenses. This gives a new degree of freedom for gradient-indexed lenses design. Furthermore, the geometric nature of derivation makes the results analytical. By using this method, we get better insight into the problem of spherical aberration. We also suggest several manufacturing methods for gradient-indexed spherical shell materials.
Evidence of High-Temperature Superconductivity at 18 K in Nanosized Rhombohedral Bi Enhanced by Ni-Doping
(2019-03-01)
Lee, Chi-Hung
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Lin, Ken-Ming
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Tang, Yu-Hui
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Wu, Bo-Yong
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Ma, Ma-Hsuan
Superconductivity in bulk rhombohedral Bi has recently been detected to appear below 0.53 mK and 5.2 mu T. Here, we unambiguously demonstrate that superconductivity in rhombohedral Bi can be greatly enhanced by incorporating Ni ions onto the Bi sites and reducing the size to the nanometer scale. The superconducting transition temperature T-C of 12 nm rhombohedral Bi nanoparticles (NPs) reaches 4 K at ambient pressure. T-C is significantly enhanced to reach 7, 12, and 18 K in 6, 8, and 10% Ni-doped Bi NPs, respectively, where superconductivity is found to coexist with ferromagnetism. Ni-doping causes a significant amount of electronic charges to shift toward the interconnecting regions between neighboring Bi ions. First-principles calculations reveal that the Ni ions serve as charge and spin suppliers for the developments of superconductivity and ferromagnetism.
Influence of Sulfonationity of Epoxy-Based Semi-Interpenetrating Polymer Networks of Sulfonated Polyimides as Proton Exchange Membranes on the Performance of Fuel Cell Application
(2010-04-01)
Wang, Yen-Zen
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Ho, Ko-Shan
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Wu, Shinn-Dar
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Hsieh, Kuo-Huang
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Lee, Chi-Hung
A novel epoxy-based semi-interpenetrating polymer networks membrane (SPIX-EP40) as the proton exchange membrane was prepared by a flexible epoxy network with sulfonated polyimide. A series of sulfonated polyamic acid (SPAA) were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2-benzidinedisulfonic acid (BDSA) and non-sulfonated diamines, such as 4,4'-diaminodiphenyl sulfone. Solid-state (13)C nuclear magnetic resonance spectra and Fourier transform infrared spectroscopy were used to verify the synchronization of the imidization of SPAA and the crosslinking reactions of epoxy. The sulfonationity of the copolymers was regulated through a variation in the molar ratio of BDSA to diamine. These membranes owned a good thermal stability and exhibited high proton conductivity that was measured as a function of temperature. The resulting SPI0.7-EP40 and SPI0.8-EP40, at 100% relative humidity, displayed proton conductivities higher than those of Nafion (R) 117. The membranes displayed higher conductivities than Nafion (R) membranes because of owning higher activational energies and higher ion exchange capacities. An isotropic swelling phenomenon in water was found for the membrane. From the results of water uptake and the microstructure analyses using transmission electron microscopy (TEM) on different sulfonated levels, it was found that the number of water clusters in SPIX-EP40 membranes increased as the increasing water uptake and the size of water cluster were changed with the sulfonation levels. TEM confirmed the widespread and well-connected hydrophilic domains, demonstrating the presence of the favorable proton-transporting performances of the SPIX-EP40 membrane. [DOI: 10.1115/1.3177383]
Micro actuated grating for multi-beam optical pickups
(2007-02-19)
Lee, Chi-Hung
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Chiu, Yi
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Shieh, Han-Ping D.
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電控工程研究所
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光電工程學系
A stress-induced curved polysilicon actuator with a grating is achieved for the application of recordable optical pickups, which have been realized on a single silicon chip using a two-layer poly-silicon and one-layer silicon nitride micro-machining process. Three diffracted beams with equal intensity in each order from the grating were generated while applying a voltage to the actuator. The switching between the single beam and multiple beams can be applied for writing data and reading data in the disc, respectively. (c) 2007 Optical Society of America.
Micro actuated grating for multi-beam optical pickups - art. no. 66200I
(2007)
Lee, Chi-Hung
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Chiu, Yi
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Shieh, Han-Ping D.
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光電工程學系
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Department of Photonics
A stress-induced curved micro actuator with a grating attached at the end is demonstrated for recordable optical storage applications. The actuator and the grating were fabricated using a two-layer poly-silicon and one-layer silicon nitride micro-machining process. Three diffracted beams with equal intensity from the grating were generated when a voltage is applied to the actuator to switch its position. The single-beam and multi-beam configurations can be used for writing and reading data in the disc, respectively.
Micro-optical pickup
(2009-07-02)
Lee, Chi-Hung
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Chiu, Yi
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Shieh, Han-Ping D
A dynamic micro-machined optical device is applied in a micro-optical pickup. The micro-optical pickup includes an actuator and a dynamic grating, wherein the actuator may be a cantilever beam electrostatic actuator, a scratch drive actuator, a magnetic actuator or an electromagnetic actuator; and the actuator is controlled by applying an external voltage. The position of the dynamic grating is switchable between on and off the optical axis. When the external voltage is applied, the on-axis dynamic grating splits the light from a laser diode into multi-beams and the micro-optical pickup can rapidly retrieve information on the disk by simultaneously reading multi-tracks on the disk with multi low energy beams. When the external voltage is turned-off, the dynamic grating is off the optical axis and the light from the laser diode will pass directly and write information into the disk with single high energy beam.
Thermoelectric Figure-of-Merit of Fully Dense Single-Crystalline SnSe
(2019-03-01)
Wei, Pai-Chun
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Bhattacharya, Sriparna
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Liu, Yu-Fei
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Liu, Fengjiao
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He, Jian
Single-crystalline SnSe has attracted much attention because of its record high figure-of-merit ZT approximate to 2.6; however, this high ZT has been associated with the low mass density of samples which leaves the intrinsic ZT of fully dense pristine SnSe in question. To this end, we prepared high-quality fully dense SnSe single crystals and performed detailed structural, electrical, and thermal transport measurements over a wide temperature range along the major crystallographic directions. Our single crystals were fully dense and of high purity as confirmed via high statistics Sn-119 Mossbauer spectroscopy that revealed < 0.35 at. % Sn(IV) in pristine SnSe. The temperature-dependent heat capacity (C-p) provided evidence for the displacive second-order phase transition from Pnma to Cmcm phase at T-c approximate to 800 K and a small but finite Sommerfeld coefficient gamma(0) which implied the presence of a finite Fermi surface. Interestingly, despite its strongly temperature-dependent band gap inferred from density functional theory calculations, SnSe behaves like a low-carrier-concentration multiband metal below 600 K, above which it exhibits a semiconducting behavior. Notably, our high-quality single-crystalline SnSe exhibits a thermoelectric figure-of-merit ZT similar to 1.0, similar to 0.8, and similar to 0.25 at 850 K along the b, c, and a directions, respectively.