• Title/Summary/Keyword: Channel Variation

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Fabrication of a Graphene Nanoribbon with Electron Beam Lithography Using a XR-1541/PMMA Lift-Off Process

  • Jeon, Sang-Chul;Kim, Young-Su;Lee, Dong-Kyu
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.4
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    • pp.190-193
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    • 2010
  • This report covers an effective fabrication method of graphene nanoribbon for top-gated field effect transistors (FETs) utilizing electron beam lithography with a bi-layer resists (XR-1541/poly methtyl methacrylate) process. To improve the variation of the gating properties of FETs, the residues of an e beam resist on the graphene channel are successfully taken off through the combination of reactive ion etching and a lift-off process for the XR-1541 bi-layer. In order to identify the presence of graphene structures, atomic force microscopy measurement and Raman spectrum analysis are performed. We believe that the lift-off process with bi-layer resists could be a good solution to increase gate dielectric properties toward the high quality of graphene FETs.

Optimization for Arrayed Waveguide Grating having MMI Coupler for Flattened Transfer Function

  • Jung, Jae-Hoon
    • Journal of the Optical Society of Korea
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    • v.10 no.4
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    • pp.169-173
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    • 2006
  • This paper describes an efficient optimal design method for an arrayed waveguide grating (AWG) having MMI coupler with flattened transfer function. The objective function is the norm of the difference between calculated and target spectra. To analyze the AWG transfer function, the Fresnel-Kirchhof diffraction formula was employed and the design variable was optical path difference of each array waveguide. The (1+1) Evolution Strategy was applied to an eight-channel coarse wavelength division multiplexing (CWDM) AWG as the optimization tool. For obtaining a broadened spectrum, we use a MMI coupler and the variation in optical path difference at each array waveguide changes the shape of the transfer function to obtain the optimal spectrum shape.

Hydraulic Model Experiment on the Circulation in Sagami Bay, Japan (III) -The Time-Varying States of the Flow Pattern and Water Exchange in Barotropic Rotating Model-

  • Choo Hyo-Sang;Sugimoto Takasige
    • Fisheries and Aquatic Sciences
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    • v.1 no.2
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    • pp.260-268
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    • 1998
  • A flow pattern and water exchange in Sagami Bay is examined using a barotropic hydraulic model. In the model experiments, the volume transports of the Kuroshio Through Flow were changed with time. The results of the model experiments show that when the volume transport is increased with time, water mass and vorticity are transferred to the inner part of the bay by wakes from the western part of the bay. In the case of decrease, as the wakes are ceased, the inner cyclonic circulation water is discharged to the outside of the bay by its southward extension through the Oshima eastern channel. It is found that the water exchange by the short-term variation of volume transport in time is about 20% of all the bay water.

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Incentivizing User Contributions in Idea Crowdsourcing through Quantitative and Qualitative Feedback : A Field Experiment

  • Cho, Sook-Hyun;Lee, Sang-Min;Moon, Jae Yun
    • Journal of Information Technology Applications and Management
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    • v.21 no.3
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    • pp.19-33
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    • 2014
  • Crowdsourcing is a popular tool for firms to harness external knowledge and resources. One variation of crowdsourcing entails the use of corporate channels in social network services (SNS) such as Twitter to hold public idea competitions. This study examined the role of feedback interaction between participants of idea competitions. More specifically, the study examined the impact of incentives to provide feedback on other participants' ideas. We found that idea competitions where explicit incentives were introduced to elicit crowdsourced feedback in the form of qualitative comments resulted in improved idea generation performance-with more ideas generated overall, and more ideas generated through participant collaborations, through increased comment-posting activities. Based on the findings, implications for theory and practice are discussed.

Analysis of High Current Copper Bus Bar Temperature in Smelting Plants (제련설비용 대전류 동 Bus Bar의 온도해석)

  • Kwak, Byung-Kil;Kim, Changl-Hwan;Choi, Byung-Ju;Kim, Kyu-Ho;Rhee, Sang-Bong
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.11
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    • pp.26-32
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    • 2014
  • In electrolysis smelting plants that using high DC current, the bus bar is most important facility for delivering the high current. The copper made bus bar is widely used for various advantages as good electrical and thermal conductivity, resonable malleability, ductility, and not rust easily. However, when high current in copper bus bar, temperature rises and maximum allowable current capacity is restricted by temperature of bus bar. In this paper, we investigated temperature variation of copper bus bar by putting cooling water channel imposed to bus bar construction. For the validity, various simulations were carried out.

Multi-finger MOSFET characteristics with channel width variation (게이트 폭의 변화에 따른 Multi-finger MOSFET의 특성 모델링)

  • Yim, Hyuck-Sang;Kang, Jung-Han;Yun, Il-Gu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.176-177
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    • 2008
  • 이 논문에서는 $0.35{\mu}m$ 공정으로 제작된 MOSFET의 고주파 동작 특성을 분석하였다. Multi-finger 형태인 게이트 폭의 길이 변화에 따른 특성 변화를 BSIM3v3 모델과 외부 기생 파라미터를 포함한 lumped element를 이용해 모델링을 하였다. 또한 Multi-finger 게이트 구조에서 게이트 finger 수의 증가에 따라 생기는 특성 변화를 각각의 구조에 따라 추출된 주요 기생 파라미터의 변화를 통해 분석하였다.

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Chemical Solution Deposition of InGaZnO Thin Films As Active Channel Layers of Thin-Film Transistors

  • Son, Dae-Ho;Kim, Jung-Hye;Kim, Dae-Hwan;Sung, Shi-Joon;Jung, Eun-Ae;Kang, Jin-Kyu;Ha, Ki-Ryong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.927-930
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    • 2009
  • We studied the solution processes of IGZO thin films and investigated the electrical characteristics of thin film transistor (TFT) with sol-gel processed InGaZn-oxide active semiconductor layer. In particular, the effect of composition variation and post annealing temperature were studied by using solutions having various metal cation ratios to optimize transistor performance.

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Packet Loss Fair Scheduling Scheme for Real-Time Traffic in OFDMA Systems

  • Shin, Seok-Joo;Ryu, Byung-Han
    • ETRI Journal
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    • v.26 no.5
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    • pp.391-396
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    • 2004
  • In this paper, we propose a packet scheduling discipline called packet loss fair scheduling, in which the packet loss of each user from different real-time traffic is fairly distributed according to the quality of service requirements. We consider an orthogonal frequency division multiple access (OFDMA) system. The basic frame structure of the system is for the downlink in a cellular packet network, where the time axis is divided into a finite number of slots within a frame, and the frequency axis is segmented into subchannels that consist of multiple subcarriers. In addition, to compensate for fast and slow channel variation, we employ a link adaptation technique such as adaptive modulation and coding. From the simulation results, our proposed packet scheduling scheme can support QoS differentiations while guaranteeing short-term fairness as well as long-term fairness for various real-time traffic.

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A Study on the Implementation of Baseband Channel Simulator for Mobile Communications (이동통신용 기저대역 채널 시뮬레이터의 구현에 관한 연구)

  • 이상천;임명섭;박한규
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.12
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    • pp.1903-1909
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    • 1989
  • In this paper, the mobile communication CH simulator is implemented in the baseband, using the Digital Signal Processor(TMS320C25), A/D and D/A converters. The Rayleigh CH is modeled by shaping the random noise source power spectrum. The statistical characteristics(Level Crossing Rate, Cumulative distribution Function, Probability Density Function) and the received fading signal's power's spectrum is observed when the doppler frequency is varied according to the variation of the vehicular velocity at the 222MHz band. And also the BER is measured when the baseband mobile CH simulator is applied to the GMSK(Gaussian Minimum Shift Keying` transmission rate: 16kbps, Bb T=0.25) modulator. The results shows the similar characteristics to be compared with the theoritically derived BER values of the discriminator type GMSK detection.

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Gate Length Optimization for Minimum Forward Voltage Drop of IGBTs

  • Moon Jin-Woo;Park Dong-Wook;Choi Yearn-Ik;Chung Sang-Koo
    • KIEE International Transactions on Electrophysics and Applications
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    • v.5C no.6
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    • pp.246-250
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    • 2005
  • The forward voltage drop of IGBT is studied numerically and analytically as a function of gate length. An analytical expression is presented for the first time for the surface potential variation along the channel layer under the gate of IGBT. The surface potential drop and the carrier density near the surface allow calculation of the forward voltage drop of IGBT analytically as a function of the gate length. The voltage-drop in the drift region near the gate decreases exponentially, whereas that on the surface increases linearly with increasing the gate length, the sum of which exhibits an optimum gate length, resulting in a minimum forward voltage drop. Based on the surface potential drop, a remodelling of the forward voltage drop of IGBT is also proposed.