• Title, Summary, Keyword: Electrical and physical performance

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High-Performance a-IGZO Thin-Film Transistor with Conductive Indium-Tin-Oxide Buried Layer

  • Ahn, Min-Ju;Cho, Won-Ju
    • Journal of the Korean Physical Society
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    • v.71 no.7
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    • pp.408-412
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    • 2017
  • In this study, we fabricated top-contact top-gate (TCTG) structure of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with a thin buried conductive indium-tin oxide (ITO) layer. The electrical performance of a-IGZO TFTs was improved by inserting an ITO buried layer under the IGZO channel. Also, the effect of the buried layer's length on the electrical characteristics of a-IGZO TFTs was investigated. The electrical performance of the transistors improved with increasing the buried layer's length: a large on/off current ratio of $1.1{\times}10^7$, a high field-effect mobility of $35.6cm^2/Vs$, a small subthreshold slope of 116.1 mV/dec, and a low interface trap density of $4.2{\times}10^{11}cm^{-2}eV^{-1}$ were obtained. The buried layer a-IGZO TFTs exhibited enhanced transistor performance and excellent stability against the gate bias stress.

Rate-capability response of graphite anode materials in advanced energy storage systems: a structural comparison

  • Farooq, Umer;Doh, Chil-Hoon;Pervez, Syed Atif;Kim, Doo-Hun;Lee, Sang-Hoon;Saleem, Mohsin;Sim, Seong-Ju;Choi, Jeong-Hee
    • Carbon letters
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    • v.17 no.1
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    • pp.39-44
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    • 2016
  • The work presented in this report was a detailed comparative study of the electrochemical response exhibited by graphite anodes in Li-ion batteries having different physical features. A comprehensive morphological and physical characterization was carried out for these graphite samples via X-ray diffraction and scanning electron microscopy. Later, the electrochemical performance was analyzed using galvanostatic charge/discharge testing and the galvanostatic intermittent titration technique for these graphite samples as negative electrode materials in battery operation. The results demonstrated that a material having a higher crystalline order exhibits enhanced electrochemical properties when evaluated in terms of rate-capability performance. All these materials were investigated at high C-rates ranging from 0.1C up to 10C. Such improved response was attributed to the crystalline morphology providing short layers, which facilitate rapid Li+ ions diffusivity and electron transport during the course of battery operation. The values obtained for the electrical conductivity of these graphite anodes support this possible explanation.

Functional Electrical Stimulation with Augmented Feedback Training Improves Gait and Functional Performance in Individuals with Chronic Stroke: A Randomized Controlled Trial

  • Yu, Kyung-Hoon;Kang, Kwon-Young
    • The Journal of Korean Physical Therapy
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    • v.29 no.2
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    • pp.74-79
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    • 2017
  • Purpose: The purpose of this study was to compare the effects of the FES-gait with augmented feedback training to the FES alone on the gait and functional performance in individuals with chronic stroke. Methods: This study used a pretest and posttest randomized control design. The subjects who signed the agreement were randomly divided into 12 experimental groups and 12 control groups. The experimental groups performed two types of augmented feedback training (knowledge of performance and knowledge of results) together with FES, and the control group performed FES on the TA and GM without augmented feedback and then walked for 30 minutes for 40 meters. Both the experimental groups and the control groups received training five times a week for four weeks. Results: The groups that received the FES with augmented feedback training significantly showed a greater improvement in single limb support (SLS) and gait velocity than the groups that received FES alone. In addition, timed up and go (TUG) test and six minute walk test (6MWT) showed a significant improvement in the groups that received FES with augmented feedback compared to the groups that received FES alone. Conclusion: Compared with the existing FES gait training, augmented feedback showed improvements in gait parameters, walking ability, and dynamic balance. The augmented feedback will be an important method that can provide motivation for motor learning to stroke patients.

An Effective Parallel Implementation of Sound Synthesis of Guitar using GPU (GPU를 이용한 기타의 음 합성을 위한 효과적인 병렬 구현)

  • Kang, Sung-Mo;Kim, Jong-Myon
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.8
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    • pp.1-8
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    • 2013
  • This paper proposes an effective parallel implementation of a physical modeling synthesis of guitar on the GPU environment. We used appropriate filter coefficients and adjusted the length of delay line for each open string to generate 44,100 six-polyphonic guitar sounds (E2, A2, D3, G4, B3, E4) by using physical modeling synthesis. In addition, we analyzed the physical modeling synthesis algorithm and observed that we can exploit parallelism inherent in the length of delay line. Thus, we assigned CUDA cores as many as the length of delay line and effectively implemented the physical modeling synthesis using GPU to achieve the highest performance. Experimental results indicated that synthetic guitar sounds using GPU were very similar to the original sounds when we compared their spectra. In addition, GPU achieved 68x and 3x better performance than high-performance TI DSP and CPU, respectively. Furthermore, this paper implemented and evaluated the performance of multi-GPU systems for the physical modeling algorithm.

Electrical Degradation on DC and RF Characteristics of Short Channel AlGaN/GaN-on-Si HEMT with Highly Doped Carbon Buffer

  • Kim, Dong-Hwan;Jeong, Jun-Seok;Eom, Su-Keun;Lee, Jae-Gil;Seo, Kwang-Seok;Cha, Ho-Young
    • Journal of the Korean Physical Society
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    • v.71 no.10
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    • pp.711-716
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    • 2017
  • In this study, we investigated the effects of highly doped carbon (C) buffer on the microwave performance of AlGaN/GaN-on-Si high electron mobility transistor (HEMT). We fabricated AlGaN/GaN-on-Si HEMTs with two different buffer structures. One structure had an un-doped buffer layer and the other structure had C-doped buffer layer with the doping concentration of ${\sim}1{\times}10^{19}cm^{-3}$ with GaN channel thickness of 350 nm. Despite higher leakage current, the device fabricated on the un-doped buffer structure exhibited better transfer and current collapse characteristics which, in turn, resulted in superior small-signal characteristics and radio frequency (RF) output power. Photoluminescence and secondary ion mass spectrometry measurements were carried out to investigate the effects of the highly-doped C buffer on microwave characteristics.

Physical Layer Design of Dual-Band Guardian Modem based on Quasi-Orthogonal Code (유사 직교 부호 기반 이중 대역 Guardian 모뎀의 물리계층 설계)

  • Lee, Hyeon-Seok;Cho, Jin-Woong;Hong, Dae-Ki
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.1
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    • pp.127-132
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    • 2013
  • In this paper, we design the physical layer of Guardian modem for wireless public networks. The physical layer is composed of a dual-band RF (Radio Frequency) transceiver and a baseband-processor with quasi-orthogonal codes. The 2.4/5GHz dual-band RF transceiver can overcome the communication difficulty of dense 2.4GHz band for wireless public environment. Also the quasi-orthogonal code can reduce the required ASIC (Application Specific Integrated Circuit) design area. Finally, we analyze the performance of the developed system in viewpoint of data rate, BER (Bit Error Rate), PER (Packet Error Rate). Moreover we verify the performance of the dual-band RF communication.

Performance Comparison of Coherent and Non-Coherent Detection Schemes in LR-UWB System

  • Kwon, Soonkoo;Ji, Sinae;Kim, Jaeseok
    • Journal of Communications and Networks
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    • v.14 no.5
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    • pp.518-523
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    • 2012
  • This paper presents new coherent and non-coherent detection methods for the IEEE 802.15.4a low-rate ultra-wideband physical layer with forward error correction (FEC) coding techniques. The coherent detection method involving channel estimation is based on the correlation characteristics of the preamble signal. A coherent receiver uses novel iterated selective-rake (IT-SRAKE) to detect 2-bit data in a non-line-of-sight channel. The non-coherent detection method that does not involve channel estimation employs a 2-bit data detection scheme using modified transmitted reference pulse cluster (M-TRPC) methods. To compare the two schemes, we have designed an IT-SRAKE receiver and a MTRPC receiver using an IEEE 802.15.4a physical layer. Simulation results show the performance of IT-SRAKE is better than that of the M-TRPC by 3-9 dB.

Physical Layer Secrecy Performance of RF-EH Networks with Multiple Eavesdroppers

  • Truong, Tien-Vu;Vo, Nhan-Van;Ha, Dac-Binh;Tran, Duc-Dung
    • Journal of information and communication convergence engineering
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    • v.14 no.3
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    • pp.171-176
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    • 2016
  • In this study, we investigate the physical layer secrecy performance of RF energy harvesting (EH) networks over Rayleigh fading channels. The RF-EH system considered here consists of one power transfer station, one source, one destination, and multiple passive eavesdroppers. The source harvests energy from the power transfer station and transmits the information to the destination by using a time switching-based relaying protocol. The eavesdroppers try to extract the transmitted information without an active attack. By using the statistical characteristics of the signal-to-noise ratio (SNR), the exact closed-form expressions of the existence probability of the secrecy capacity and the secrecy outage probability are derived. Further, we analyze the secrecy performance of the system with respect to various system parameters, such as the location of the system elements and the number of eavesdroppers. Finally, the equivalent Monte Carlo simulation results are provided to confirm the correctness of our calculations.

A New Comb Circular Polarizer Suitable for Millimeter-Band Application

  • Eom, Soon-Young;Korchemkin, Y.B.
    • ETRI Journal
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    • v.28 no.5
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    • pp.656-659
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    • 2006
  • This letter presents a new polarizer which has a simple comb structure inside a circular waveguide. The electrical performance of the proposed comb polarizer is optimized by a circular waveguide radius and by the physical parameters of the comb plates. This polarizer is suitable for providing good performance in millimeter-band application because of its simple structure and low fabrication cost. In our experiments the dual-band comb polarizer designed in band 1(K) and band 2(Ka) showed good electrical performance without any tuning elements.

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Electrical Characteristic of Blend with LLDPE and EVA Due to Mixing Ratio (혼합비에 따른 선형저밀도 폴리에틸렌과 에틸렌비닐아세테이트 블랜드의 전기적 특성)

  • 신종열;이충호;홍진웅
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.6
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    • pp.525-532
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    • 2001
  • In this paper, physical properties and electrical characteristics of linear low density polyethylene(LLDPE) films blended with ethylene vinyl acetate(EVA), containing polar groups within it, were investigated to improve defects of polyethylene(PE) such like space charge accumulation and tree growth. Blending method changes super-structure of LLDPE, having a great influence on electrical characteristics. For analysis of physical properties, FTIR, XRD and DSC methods were executed, and for electrical characteristics, volume resistivity and dielectric strength were measured with the varying temperature. From the results, it is confirmed that bled specimens tend to be safe to varying temperature, and specially of 70:30 and 50:50 have a good performance.

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