Browsing by Author "Chen, Yi-Ching"

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93% Complexity Reduction of Volterra Nonlinear Equalizer by l(1)-Regularization for 112-Gbps PAM-4 850-nm VCSEL Optical Interconnect
(2018-01-01)
Huang, Wan-Jou
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Chang, Wei-Fan
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Wei, Chia-Chien
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Liu, Jun-Jie
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Chen, Yi-Ching
We successfully transmit a 112-Gbps PAM-4 signal over 200-m OM4 fiber using 850-nm VCSEL and Volterra filter. Adopting l(1)-regularization can reduce 93% of computation complexity of Volterra filter at the KP4 FEC limit.
Acute Type A Aortic Dissection Successfully Managed with One-stage Surgery of Total Aortic Arch Replacement with Supra-aortic Transposition Plus Frozen Elephant Trunk Technique
(2014-09-01)
Lee, Meng-Lin
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Sun, Shen
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Chen, Yi-Ching
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Lee, Ying-Chun
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Lin, Jiunn-Miin
Acute type A aortic dissection has long been a challenging issue. The surgical techniques traditionally vary with the anatomic extent of the aortic dissection. Simple ascending aortic grafting can be lifesaving, but the lesions beyond the aorta, which include the arch vessels and descending aorta, remain potential hazards. In this paper, we present a patient in which acute type A aortic dissection with lesions extending into descending thoracic aorta was successfully managed by total arch replacement with supra-aortic transposition plus the frozen elephant trunk technique to the descending aorta. A 67-year-old gentleman presented with severe tearing pain from the anterior to posterior chest. Computed tomography confirmed the diagnosis of acute type A dissection extending to the level of the right common iliac artery. An emergent operation was performed as in the aforementioned technique. The surgery went well and the patient was discharged without comorbidities on postoperative day 25. The patient had regular outpatient clinical follow-up. The follow-up computed tomography images showed adequate results with the obliteration of the false lumen. In conclusion, total aortic arch replacement with supra-aortic transposition plus frozen elephant trunk technique is a safe and feasible operative method for patients with detrimental acute type A aortic dissection. Copyright (C) 2014, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC. All rights reserved.
Design and Analysis of Multi-User Association and Beam Training Schemes for Millimeter Wave Based WLANs
(2020-07-01)
Shen, Li-Hsiang
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Chen, Yi-Ching
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
Millimeter wave (mmWave) in the unlicensed 60 GHz band provides extremely large spectrum utilization, which is a promising technique due to the rapid growth of wireless communication services. With wireless devices explosively increasing, the limited number of association and beamforming training (A-BFT) opportunities in conventional protocol leads to high packet collisions. In this paper, we design a novel non-slotted A-BFT frame structure for multi-users in order to alleviate packet collisions providing flexible training slots. To further reduce collision occurrence, we propose two association mechanisms including the time-based distributed coordination function (TDCF) and time-based beam collision avoidance (TBCA) schemes. The theoretical closed-forms of both TDCF and TBCA methods are also derived, and proved to outperform the random association. Furthermore, the adaptive beam search (ABS) and dynamic A-BFT adjustment (DAA) schemes are proposed to consider historical beam training information by adjusting the number of training beams and A-BFT length, respectively. Simulations are conducted to show that our proposed ABS, DAA, and TDCF/TBCA mechanisms outperform existing methods; whereas higher spectrum efficiency can be achieved by proposed non-slotted frame structure compared to conventional slotted structure.
Effects of supercritical fluids activation on carbon nanotube field emitters
(2007-01-01)
Liu, Po-Tsun
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Tsai, Chih-Tsung
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Chang, Ting- Chang
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Kin, Kon-Tsu
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Chang, Pei-Lin
This paper proposes a novel method to enhance the emission characteristics of carbon nanotubes (CNTs). It is extremely possible for CNTs to adsorb moisture and other contaminants during the fabrication processes, leading to the degraded field emission characteristics. In., this work, CNT emitters are activated with commonly used heating process and supercritical carbon dioxide (SCCO2) fluids technology for removing adsorbed residue moisture. Experimental results have demonstrated that the electrical stability and field emission enhancement of CNT emitters are effectively achieved by the SCCO2 fluids treatment compared to the heating process, due to the minimization of residuary moisture in CNTs.
Enhanced Multi-User Beamforming Protocol for Millimeter Wave Wireless Local Area Networks
(2018-01-01)
Chen, Yi-Ching
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Shen, Li-Hsiang
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
MmWave in the unlicensed 60GHz band is highly discussed due to the rapid growth of wireless communication services. The utilization of microwave spectrum below 10 GHz is almost reaching its limit. Beamforming (BF) has become an essential technique to compensate the high path loss phenomenon of mmWave. IEEE 802.11ad and 802.11ay standardization task group institute directional multi-gigabit (DMG) wireless local area networks (WLANs) supporting mmWave techniques. With wireless devices explosively increasing, the limited number of BF slots in conventional DMG protocols leads to high packet collision probability, which potentially degrades the system performance. Most of the existing research does not take the multi-user BF contention problem into consideration. In this paper, we design a non-slotted association beamforming training (A-BET) frame structure for multi-users without separating A-BFT slots in order to alleviate packet collisions due to the shortage of contention and training frames. This new proposed structure allows collisions with useful information left in remaining non-collided slots or frames in order to leverage the insufficiency of BF training for multiple devices. Furthermore, in order to further reduce BF collision probability, we propose two multiuser beamforming training mechanisms, including the time-based distributed coordination function (TDCF) and time-based beam-collision avoidance (TBCA) schemes. Simulation results demonstrate that our new proposed frame structure along with proposed TDCF and TBCA mechanisms outperforms 802.11ad protocol.
Improvement of quantum efficiency in green light-emitting diodes with pre-TMIn flow treatment
(2011-06-08)
Lee, Ya-Ju
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Chen, Yi-Ching
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Lu, Tien-Chang
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光電工程學系
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Department of Photonics
The effects of pre-trimethlyindium (TMIn) flow on the improved electrical characteristics and highly stable temperature properties of InGaN green light-emitting diodes (LEDs) are discussed. For the LED sample with a pre-TMIn flow treatment, the tunnelling of injected carriers associated with threading defects is significantly reduced, which promotes the diffusion-recombination of injected carriers, as well as the overall emission efficiency of the LED. In addition, the pre-TMIn flow treatment evidently reduces the dependence of external quantum efficiency on temperature and efficiency droop of green LEDs. As a result, we conclude that the pre-TMIn flow treatment is a promising scheme for the improvement of output performance of InGaN-based green LEDs.
Mobility-Aware Fast Beam Training Scheme for IEEE 802.11ad/ay Wireless Systems
(2018-01-01)
Shen, Li-Hsiang
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Chen, Yi-Ching
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Feng, Kai-Ten
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電機工程學系
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Department of Electrical and Computer Engineering
Millimeter wave (mmWave) technology provides multi-Gbps services thanks to huge spectrum usage. IEEE 802.11ad/ay standardizes the next generation wireless local area networks (WLANs) for high data rate transmissions at 60 GHz band. Directional beamforming (BF) transmissions overcome the difficulty of high signal attenuation. In addition, a beam sector based scheme for BF training is taken by 802.11ad/ay to tackle sophisticated indoor environments. However, conventional exhaustive beam search (EBS) takes much time and some literatures try to design to reduce training latency. Also, most of papers do not consider about the mobility effect of moving devices, which deteriorates the beam matching outcomes. With the consideration of beam matching accuracy and mobility effects corresponding to historically observed transmitted beams, we propose the mobility-aware fast beam training (MFBT) algorithm. Simulation results show how mobility affects the system in terms of latency and throughput. There are trade-offs when operating with different beamwidth and matching accuracy requirements. Moreover, our proposed algorithm achieves lower latency and higher throughput than other existing beam training schemes.
Pharmacologically upregulated carcinoembryonic antigen-expression enhances the cytolytic activity of genetically-modified chimeric antigen receptor NK-92MI against colorectal cancer cells
(2018-08-03)
Shiozawa, Masayuki
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Chang, Chuan-Hsin
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Huang, Yi-Chun
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Chen, Yi-Ching
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Chi, Mau-Shin
Background: The natural killer cell line, NK-92MI, is cytotoxic against various types of cancer. The aim of this study was to develop chimeric antigen receptor-modified (CAR) NK-92MI cells targeting carcinoembryonic antigen-expressing (CEA) tumours and increase killing efficacy by pharmacologically modifying CEA-expression. Result: We generated anti-CEA-CAR NK-92MI cells by retroviral vector transduction. This genetically-modified cell line recognised and lysed high CEA-expressing tumour cell lines (LS174T) at 47.54 +/- 12.60% and moderate CEA-expressing tumour cell lines (WiDr) at 31.14 +/- 16.92% at a 5:1 effector: target (E/T) ratio. The cell line did not lyse low CEA-expressing tumour cells (HCT116) as they did their parental cells (NK-92MI cells). The histone deacetylase-inhibitor (HDAC) sodium butyrate (NaB) and the methylation-inhibitor 5-azacytidine (5-AZA), as epigenetic modifiers, induced CEA-expression in HCT116 and WiDr cells. Although the IC50 of 5 fluorouracil (5-FU) increased, both cell lines showed collateral sensitivity to anti-CEA-CAR NK-92MI cells. The cytolytic function of anti-CEA-CAR NK-92MI cells was increased from 22.99 +/- 2.04% of lysis background to 69.20 +/- 11.92% after NaB treatment, and 69.70 +/- 9.93% after 5-AZA treatment, at a 10:1 UT ratio in HCT116 cells. The WiDr cells showed similar trend, from 22.99 +/- 4.01% of lysis background to 70.69 +/- 10.19% after NaB treatment, and 59.44 +/- 10.92% after 5-AZA treatment, at a 10:1 E/T ratio. Conclusions: This data indicates that the effector-ability of anti-CEA-CAR NK-92MI increased in a CEA-dependent manner. The combination of epigenetic-modifiers like HDAC-inhibitors, methylation-inhibitors, and adoptive-transfer of ex vivo-expanded allogeneic-NK cells may be clinically applicable to patients with in 5-FU resistant condition.
Stable Temperature Characteristics and Suppression of Efficiency Droop in InGaN Green Light-Emitting Diodes Using Pre-TMIn Flow Treatment
(2010-09-01)
Lee, Ya-Ju
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Chen, Yi-Ching
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Lee, Chia-Jung
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Cheng, Chun-Mao
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Chen, Shih-Wei
We present experimental results on the improved performance and high stable temperature characteristics of the InGaN green light-emitting diode (LED) with pre-trimethlyindium (pre-TMIn) flow treatment. By using pre-TMIn flow treatment, a relatively large radiative coefficient (B = 3.34 x 10(-11) cm(3).s(-1))corresponding to a 9.2% enhancement in the internal quantum efficiency, as well as a significant reduction of leakage paths for injected carriers, was obtained. Most important, the pre-TMIn flow treatment evidently reduces the dependence of the external quantum efficiency on temperature and efficiency droop of green LEDs. The improvement is thought to be attributable to the preferential formation of In-rich dots upon pre-TMIn flow treatment, which effectively suppresses the trapping of excitons by threading dislocations and the overflowing of injected carriers outside the active regions at elevated temperatures.