Browsing by Issue Date, starting with "2009-03-23"

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Directional light extraction enhancement from GaN-based film-transferred photonic crystal light-emitting diodes
(2009-03-23)
Lai, Chun-Feng
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Chao, Chia-Hsin
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Kuo, Hao-Chung
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Yen, His-Hsuan
;
Lee, Chia-En
Experimental investigation of the directionality in the far-field pattern and light extraction enhancement in collected cone were performed in GaN-based film-transferred photonic crystal (PhC) light-emitting diodes (FTLEDs). Angular-resolved measurement revealed directional profile and azimuthal anisotropy in the far-field distribution with guided modes extraction. Good agreement according to Bragg's diffraction theory and free photon band structure were achieved. The light enhancement in PhC FTLEDs compared to non-PhC FTLEDs within the collection cone angle was obtained according to measured three-dimensional far-field patterns. In a +/- 20 degrees collection cone, collected light was enhanced by a factor of similar to 2.4 for the collimated PhC FTLED.
Domain growth dynamics in single-domain-like BiFeO3 thin films
(2009-03-23)
Chen, Y. C.
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Lin, Q. R.
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Chu, Y. H.
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材料科學與工程學系
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Department of Materials Science and Engineering
We present a quantitative study of 180 degrees domain wall motion in epitaxial BiFeO3 (111) films, which can be treated as a nearly ideal single-domain environment. The domains were dynamically written by applying voltage pulses and examined by the piezoresponse force microscope technique. A transition of domain growth behaviors from the activated type to the nonactivated type was observed when increasing the pulse voltages. The obtained activation field was close to the ideally thermodynamic switching field of BiFeO3. The asymmetry of activated fields showed the preference of the downward polarization in the BiFeO3/SrRuO3 films.
Domain growth dynamics in single-domain-like BiFeO(3) thin films
(2009-03-23)
Chen, Y. C.
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Lin, Q. R.
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Chu, Y. H.
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材料科學與工程學系
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Department of Materials Science and Engineering
We present a quantitative study of 180 degrees domain wall motion in epitaxial BiFeO(3) (111) films, which can be treated as a nearly ideal single-domain environment. The domains were dynamically written by applying voltage pulses and examined by the piezoresponse force microscope technique. A transition of domain growth behaviors from the activated type to the nonactivated type was observed when increasing the pulse voltages. The obtained activation field was close to the ideally thermodynamic switching field of BiFeO(3). The asymmetry of activated fields showed the preference of the downward polarization in the BiFeO(3)/SrRuO(3) films.
Nanotip fabrication of zinc oxide nanorods and their enhanced field emission properties
(2009-03-25)
Yao, I-Chuan
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Lin, Pang
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Tseng, Tseung-Yuen
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材料科學與工程學系
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電子工程學系及電子研究所
The ZnO nanorods on ZnO/Si substrates were synthesized by using the low temperature growth aqueous solution method. The chemical and plasma etching treatments were carried out on the as-grown ZnO nanorods to provide the nanorods with various tip angles. The crystal structure and morphology of the ZnO nanorods were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The nanorods grew along the [ 0001] direction and had various tip angles formed after the above etching processes. The field emission properties of the ZnO nanorods with tip angles of 110 degrees and 85 degrees are: the turn-on electric fields (at the current density of 10 mu A cm(-2)) are about 3.03 and 1.70 V mu m(-1), respectively, while field enhancement factors are 1972 and 3513, respectively. The lifetime measurement result indicates the turn-on field of the ZnO nanostructures reaches a stable value during 1000 cycle times. The enhanced field emission properties are believed to benefit from decreased tip angle of the nanorod emitter.
The characterization of a single discrete bionanodot for memory device applications
(2009-03-25)
Miura, Atsushi
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Tanaka, Ryota
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Uraoka, Yukiharu
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Matsukawa, Nozomu
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Yamashita, Ichiro
We investigated electronic properties of a biochemically synthesized cobalt oxide bionanodot (Co-BND) by means of scanning tunneling microscopy/spectroscopy (STM/STS) and Kelvin-probe force microscopy (KFM). Experimentally obtained I-V characteristics and numerically obtained dI/dV and (dI/dV)/(I/V) from I-V revealed the band gap energy, band position of valence and conduction band of the Co-BND. KFM observation shows that bias polarity dependent surface potential change after charge injection. The observed surface potential change indicates that the Co-BND has a charge storage capability. We demonstrated the application of Co-BNDs for electronic devices by choosing flash memory as the example device. The fabricated Co-BND embedded MOS memory showed clear memory operation due to the charge confinement in the embedded Co-BNDs.
Combined Experimental and Theoretical Study of Long-Range Interactions Modulating Dimerization and Activity of Yeast Geranylgeranyl Diphosphate Synthase
(2009-03-25)
Lo, Chia-Hsiang
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Chang, Ying-Hsuan
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Wright, Jon D.
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Chen, Shih-Hsun
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Kan, Daphne
We present here how two amino acid residues in the first helix distal from the main dimer interface modulate the dimerization and activity of a geranylgeranyl diphosphate synthase (GGPPs). The enzyme catalyzes condensation of farnesyl diphosphate and isopentenyl diphosphate to generate a C(20) product as a precursor for chlorophylls, carotenoids, and geranylgeranylated proteins. The 3D structure of GGPPs from Saccharomyces cerevisiae reveals an unique positioning of the N-terminal helix A, which protrudes into the other subunit and stabilizes dimerization, although it is far from the main dimer interface. Through a series of mutants that were characterized by analytic ultracentrifugation (AUC), the replacement of L8 and 19 at this helix with Gly was found sufficient to disrupt the dimer into a monomer, leading to at least 10(3)-fold reduction in activity. Molecular dynamics simulations and free energy decomposition analyses revealed the possible effects of the mutations on the protein structures and several critical interactions for maintaining dimerization. Further site-directed mutagenesis and AUC studies elucidated the molecular mechanism for modulating dimerization and activity by long-range interactions.
A hybrid controller design for bi-axial inverted pendulum system
(2009-03-25)
Chang, Long-Hong
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Lee, An-Chen
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機械工程學系
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Department of Mechanical Engineering
This study presents the use of Tustin's friction model and a disturbance observer (DOB) to improve the steady-state error (SSE) of a bi-axial inverted pendulum-cart system (IPCS). Furthermore, a hybrid controller contains a feedback linearization control for pendulum angle in the region of 3-12 degrees to enlarge the angle of operation and an H(infinity) control using loop shaping design procedure (LSDP) for cart position and pendulum angle in the region of 0-3 degrees to stabilize the IPCS, respectively. Experimental results reveal that the pendulum maximum angle of operation is improved from 7 to 12; the SSE of the angle of the pendulum is reduced from 0.85 to 0.1 degrees, and the SSE of the position of the cart is reduced from 10 to 1.4 mm. Experimental results are illustrated and films are provided at the web site http://hinfinity.myweb.hinet.net to show the effectiveness and robustness of the hybrid controller with Tustin's friction model and DOB compensation. Copyright (c) 2008 John Wiley & Sons, Ltd.
Method of alignments of liquid crystal employing magnetic thin films
(2009-03-26)
Chao, Ru-Pin
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Wu, Hsin-Ying
Alignments of liquid crystal are obtained. A transparent magnetic thin film provides a homeotropic alignment of liquid crystal molecules. Or, a homeotropic or homogeneous alignment having an adjustable pretilt angle is further obtained through rubbing the transparent magnetic thin film. The present invention has a simple procedure with a low cost. The present invention is used in equipment with a plasma source while providing high transmittance, hardness and insulation. And the transparent magnetic thin film has potential uses in the applications of non-contact multi-domain alignment without extra procedure for alignment treatment.
Convertible multi-authenticated encryption scheme with one-way hash function
(2009-03-27)
Tsai, Jia-Lun
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數位內容製作中心
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Center for Digital Content Production
To send the message to the recipient securely, authenticated encryption schemes were proposed. In 2008, Wu et al. [T.S, Wu, C.L. Hsu, K.Y. Tsai, H.Y. Lin, T.C. Wu. Convertible multi-authenticated encryption scheme, Information Sciences 178 (1) 256-263.] first proposed a convertible multi-authenticated encryption scheme based on discrete logarithms. However, the author finds that the computational complexity of this scheme is rather high and the message redundancy is used. To improve the computational efficiency and remove the message redundancy. the author proposes a new convertible multi-authenticated encryption scheme based oil the intractability of one-way hash functions and discrete logarithms. As for efficiency, the computation cost of the proposed scheme is smaller than Wu et al.'s scheme. (C) 2008 Elsevier B.V. All rights reserved.
Structural change of ionic association in ionic liquid/water mixtures: A high-pressure infrared spectroscopic study
(2009-03-28)
Umebayashi, Yasuhiro
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Jiang, Jyh-Chiang
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Shan, Yu-Lun
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Lin, Kuan-Hung
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Fujii, Kenta
High-pressure infrared measurements were carried out to observe the microscopic structures of two imidazolium-based ionic liquids, i.e., 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [EMI(+)(CF(3)SO(2))(2)N(-), EMI(+)TFSA(-)] and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide [EMI(+)(FSO(2))(2)N(-), EMI(+)FSA(-)]. The results obtained at ambient pressure indicate that the imidazolium C-H may exist in two different forms, i.e., isolated and network structures. As the sample of pure EMI(+)FSA(-) was compressed, the network configuration is favored with increasing pressure by debiting the isolated form. For EMI(+)TFSA(-)/H(2)O mixtures, the imidazolium C-H peaks split into four bands at high pressures. The new spectral features at approximately 3117 and 3190 cm(-1), being concentration sensitive, can be attributed to the interactions between the imidazolium C-H and water molecules. The alkyl C-H absorption exhibits a new band at approximately 3025 cm(-1) under high pressures. This observation suggests the formation of a certain water structure around the alkyl C-H groups. The O-H stretching absorption reveals two types of O-H species, i.e., free O-H and bonded O-H. For EMI(+)TFSA(-)/H(2)O mixtures, the compression leads to a loss of the free O-H band intensities, and pressure somehow stabilizes the bonded O-H configurations. The results also suggest the non-negligible roles of weak hydrogen bonds in the structure of ionic liquids.
Earthlings
(2009-03-29)
趙祿平
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Department of Communication and Technology
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傳播與科技學系
“如果我能讓世界上每一個人看一部電影的話，我會要他們看《地球上的生靈》（Earthlings）。”～哲學家與倫理學家彼德‧辛格（Peter Singer）
甜食之王巧克力
(2009-03-29)
洪效凡
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Department of Communication and Technology
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傳播與科技學系
巧克力稱霸於甜食界，出現在許多舞台上，它可做為蛋糕原料、甜食副料、或者成為甜點主食。在名瑯滿目的巧克力世界裡，消費者臣服在它的魅力之下，甘願與之陪伴到天長地久。
莫妮卡的芒果雨
(2009-03-29)
梁素茵
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Department of Communication and Technology
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傳播與科技學系
莫妮卡的芒果雨
青春。搖滾。《海洋熱》
(2009-03-29)
楊純芳
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Department of Communication and Technology
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傳播與科技學系
每年七月，全台大大小小的樂團為了站上福隆海邊的大舞台，無不卯足全力奮戰，希望有一天能站上夢幻般的演唱會大舞台，對著台下萬人聽眾表演。導演陳龍男於2003年拍攝長達二小時的記錄片《海洋熱》，記載2003年第四屆貢寮海洋音樂祭的選拔實錄，記錄五個入圍樂團的青春搖滾追夢之旅。
紅與藍之間　桑傑里拉說愛
(2009-03-29)
陳怡秀
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Department of Communication and Technology
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傳播與科技學系
寶萊塢專題
眾星雲集《花樣男子》再掀熱潮　
(2009-03-29)
鄭秀芳
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Department of Communication and Technology
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傳播與科技學系
0
中性正夯！挑戰你的審美觀
(2009-03-29)
徐苾芬
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Department of Communication and Technology
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傳播與科技學系
中性風正夯
自傳改編電影一窺社會端倪
(2009-03-29)
楊睿愷
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Department of Communication and Technology
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傳播與科技學系
《無家可歸的中學生》、《佐賀的超級阿嬤》、《東京鐵塔》相互對照
向日葵大叔與葵瓜子小姐
(2009-03-29)
曾韋澐
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Department of Communication and Technology
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傳播與科技學系
我上面寫了"圖文"，就不要幫我加"圖說"了喔~謝謝
我希望的喀報
(2009-03-29)
邵奕儒
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Department of Communication and Technology
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傳播與科技學系
這不是藝文手冊