Browsing by Author "Chen, Yu-Sheng"

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A Beam-Switching Tapered Slot Antenna Array with an 8 x 8 Butler Matrix
(2015)
Chen, Yu-Sheng
;
Chou, Te-Hsin
;
Lin, Yu-De
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, a planar beam-switching array was realized by combining a tapered slot antenna array with an 8 x 8 Butler matrix. The 8 x 8 Butler matrix was implemented in the microstrip-line form, with hybrid couplers and delay lines appropriately arranged. The tapered slot antenna array was designed with suitable length and inter-element spacing to fully utilize the beam-switching capability. Measured radiation patterns of the integrated planar array showed the desired beam-switching feature when the array was fed through various input ports.
Angular color variation in micron-scale light-emitting diode arrays
(2019-08-05)
Yang, Shu-Mei
;
Wang, Po-Hsun
;
Chao, Chia-Hsin
;
Chu, Chun-Wen
;
Yeh, Yin-Tien
A simulation scheme was developed to explore the light distribution of full-color micron-scale light-emitting diode (LED) arrays. The influences of substrate thickness, patterning, and cutting angle of the substrate on several important features, such as light field pattern, light extraction efficiency, and color variation, were evaluated numerically. An experiment was conducted; the results were consistent with simulation results for a 225 x 125 mu m(2) miniLED and those for an 80 x 80 mu m(2) microLED. Based on the simulation results, the light extraction efficiency of LED devices with a substrate increases by 67.75% over the extraction efficiency of those without a substrate. The light extraction efficiency of LED devices with a substrate increases by 113.55% when an additional patterned design is used on green and blue chips. The calculated large angle Delta u'v' can be as low as 0.015 for miniLED devices. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Chemical mimicry of viral capsid self-assembly via corannulene-based pentatopic tectons
(2019-08-01)
Chen, Yu-Sheng
;
Solel, Ephrath
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Huang, Yi-Fan
;
Wang, Chien-Lung
;
Tu, Tsung-Han
Self-assembly of twelve pentatopic tectons, which have complementary edges or can be linked using either digonal or trigonal connectors, represents the optimal synthetic strategy to achieve spherical objects, such as chemical capsids. This process requires conditions that secure uninterrupted equilibria of binding and self-correction en route to the global energy minimum. Here we report the synthesis of a highly soluble, deca-heterosubstituted corannulene that bears five terpyridine ligands. Spontaneous self-assembly of twelve such tectons with 30 cadmium(II) cations produces a giant icosahedral capsid as a thermodynamically stable single product in high yield. Nuclear magnetic resonance (NMR) methods, mass spectrometry analyses, small-angle X-ray scattering, transmission electron microscopy, and atomic force microscopy indicate that this spherical capsid has an external diameter of nearly 6 nm and shell thickness of 1 nm, in agreement with molecular modeling. NMR and liquid chromatography evidences imply that chiral self-sorting complexation generates a racemic mixture of homochiral capsids.
Design Space Analysis for Cross-Point 1S1MTJ MRAM: Selector-MTJ Cooptimization
(2020-08-01)
Chiang, Hung-Li
;
Chen, Tzu-Chiang
;
Song, Ming-Yuan
;
Chen, Yu-Sheng
;
Chiu, Jung-Piao
To increase the density of magnetoresistive random accessmemory (MRAM) beyond the 1T1MTJMRAM cell in use today, the design space for 1S1MTJ MRAM array is analyzed by cooptimizing both selectors and MTJs. Current low-resistance MTJs for 1T1MTJ MRAM are not suitable for 1S1MTJ MRAM. Threshold-type selectors would induce a strong read disturb on the MTJ due to the snapback voltage (V-TH-V-HOLD) when the selector is turned on. Also, exponential-type selectorswould degrade the read margin (RM) due to its large ON-state resistance. When using existing selectors to achieve a 1-M-bit 1S1MTJ array, it is necessary to adjust the product of resistance and area (RA) and the diameter of the MTJ. An MTJ with the RA = 15 Omega . mu m(2) and the diameter = 50 nm can meet the criterion of RM > 10% for both exponential-type selectors (exponential slope = 300-500 mV/decade with the current density similar to 1 MA/cm(2)) and threshold-type selectors (V-TH-V-HOLD similar to 250 mV). A design space accommodating a selector variation of around 1% can be found for MTJs with tunnel magnetoresistance ratio (TMR) < 250%. With an increased TMR of 250%-350% of the MTJ, the tolerance of variations for exponential-type selectors and threshold-type selectors can be improved to 2% and 4%, respectively. This provides a chance for the 1S1MTJ MRAM with existing selectors.
Forming-free HfO2 Bipolar RRAM Device with Improved Endurance and High Speed Operation
(2009)
Chen, Yu-Sheng
;
Wu, Tai-Yuan
;
Tzeng, Pei-Jer
;
Chen, Pang-Shiu
;
Lee, Heng-Yuan
Fur regulation of the capsular polysaccharide biosynthesis and iron-acquisition systems in Klebsiella pneumoniae CG43
(2011-02-01)
Lin, Ching-Ting
;
Wu, Chien-Chen
;
Chen, Yu-Sheng
;
Lai, Yi-Chyi
;
Chi, Chia
The ferric uptake regulator Fur has been reported to repress the expression of rmpA, a regulatory gene for the mucoid phenotype, leading to decreased capsular polysaccharide (CPS) biosynthesis in Klebsiella pneumoniae CG43. Here, quantitative real-time FOR (qRT-PCR) analyses and electrophoretic mobility shift assays showed that Fur also repressed the expression of the CPS regulatory genes rmpA2 and rcsA. Interestingly, deletion of rmpA or rcsA but not rmpA2 from the Delta fur strain was able to suppress the deletion effect of Fur. The availability of extracellular iron affected the amount of CPS, suggesting that Fur regulates CPS biosynthesis in an Fe(II)-dependent manner. Increased production of siderophores was observed in the Delta fur strain, suggesting that uptake of extracellular iron in K. pneumoniae is regulated by Fur. Fur titration assays and qRT-PCR analyses demonstrated that at least six of the eight putative iron-acquisition systems, identified by a BLAST search in the contig database of K. pneumoniae CG43, were directly repressed by Fur. We conclude that Fur has a dual role in the regulation of CPS biosynthesis and iron acquisition in K. pneumoniae.
Prefetching for Array Data in Embedded Java Hardware Accelerator
(2009)
Wu, Yi-Ruei
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Chen, Yu-Sheng
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Shann, Jean Jyh-Jiun
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資訊工程學系
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Department of Computer Science
For improving the efficiency of a program, it is important to reduce stalls caused by memory access. Traditional programs usually spend much time on memory stalls when accessing lower-level memory, and so do Java programs. In order to reduce memory stall time, prefetching is a feasible solution. We observed some obvious properties of array access so that we could prefetch array data by taking advantage of these properties. We analyzed these properties and proposed a suitable array prefetching mechanism for embedded Java hardware accelerators so as to reduce the time spent on memory stalls, Our approach eliminates about 25% of array stall time on average and even up to 50% for some array-based programs.
Simulation-based study of negative-capacitance double-gate tunnel field-effect transistor with ferroelectric gate stack
(2016-04-01)
Liu, Chien
;
Chen, Ping-Guang
;
Xie, Meng-Jie
;
Liu, Shao-Nong
;
Lee, Jun-Wei
The concept of ferroelectric (FE) negative capacitance (NC) may be a turning point in overcoming the physical limitations imposed by the Boltzmann tyranny to realize next-generation state-of-the-art devices. Both the body factor (m-factor) and the transport mechanism (n-factor) are simultaneously improved by integrating an NC with a tunnel FET (TFET). The modeling approach is discussed in this study as well as the NC physics. By optimizing the thicknesses of FE, semiconductor, and interfacial layers, the capacitance of the FE layers is modulated to match that of a MOS resulting in the smallest subthreshold swing that is also hysteresis-free. An ultrathin-body double gate tunnel FET (UTB-DG-TFET) exhibits a steep slope (a subthreshold swing below 10 mV/dec over more than 4 orders of magnitude) for low-power applications (<0.2V switching voltage) to realize next-generation state-of-the-art devices. (C) 2016 The Japan Society of Applied Physics
Simulation-based study of negative-capacitance double-gate tunnel field-effect transistor with ferroelectric gate stack
(2016-04)
Liu, Chien
;
Chen, Ping-Guang
;
Xie, Meng-Jie
;
Liu, Shao-Nong
;
Lee, Jun-Wei
The concept of ferroelectric (FE) negative capacitance (NC) may be a turning point in overcoming the physical limitations imposed by the Boltzmann tyranny to realize next-generation state-of-the-art devices. Both the body factor (m-factor) and the transport mechanism (n-factor) are simultaneously improved by integrating an NC with a tunnel FET (TFET). The modeling approach is discussed in this study as well as the NC physics. By optimizing the thicknesses of FE, semiconductor, and interfacial layers, the capacitance of the FE layers is modulated to match that of a MOS resulting in the smallest subthreshold swing that is also hysteresis-free. An ultrathin-body double gate tunnel FET (UTB-DG-TFET) exhibits a steep slope (a subthreshold swing below 10 mV/dec over more than 4 orders of magnitude) for low-power applications (<0.2V switching voltage) to realize next-generation state-of-the-art devices. (C) 2016 The Japan Society of Applied Physics
The photonic properties of micro/mini LED arrays with different substrate thickness
(2020-01-01)
Yang, Shu-Mei
;
Wang, Po-Hsun
;
Chao, Chia-Hsin
;
Chu, Chun-Wen
;
Chen, Yu-Sheng
In this study, we review our progress in micro/mini LED arrays and their numerical simulation in optical fields. The variation in substrate thickness will be included in the calculation and the results can provide detailed insight for the optimization of the micro/mini LED structures.