• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.89-95
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• 1996

In this ppaer, temeprature dependent transport and heat transport models have been incorperated to the two dimensional device simulator SNU-2D provides a solid bse for nonisothermal device simulation. As an example to study the nonisothermal problem. we consider SOI MOSFET's I-V characteristics have been simulated and compared with the measurements. It is shown that negative slopes in the Ids-Vds characteristics are casused by the temperature dependence of the saturation velocity and the degradation of the temperature dependence mobility. Also it is shown that the kink effect occurs when impact ionization near the drain produces a buildup of holes in this isolated device island, and the hysteresis is caused by the creation of holes in the channel and their flow to the source.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.209-210
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• 2016

최근 SDN (Software-Defined Networks)에 대한 관심이 증가함에 따라 개인, 학교, 연구소에서 쉽고 간편하게 가상의 네트워크를 구성하고 SDN 기반 네트워크를 테스트를 수행할 수 있는 Mininet이 많이 활용되고 있다. 또한, 여러 SDN 컨트롤러 중에서 ONOS 컨트롤러는 OpenSource로 공개되어 GUI를 이용해 네트워크의 전반적인 토폴로지와 Flow 관리를 쉽게 할 수 있는 성숙된 컨트롤러로 인식되고 있다. 본 논문에서는 Mininet과 ONOS 컨트롤러를 이용하여 SDN 네트워크를 구성하고, 노드가 각 스위치를 이동하여 다닐 때에도 통신이 올바르게 유지되도록 컨트롤하는 시나리오를 구현하고 그 실험 결과를 제시하였다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.9
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• pp.609-618
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• 1988

Two dimensional numericl analysis program of power VDMOSFET structure has been developed. Modeling for equipotential distribution, current flow pattern and carrier distribution are presented. I-V characteristic curves due to saturation velocity, mobility value, transconductance and on-resistance are studied by comparison of computer simulated results and exeperimental data. These are found to agree with the simulated results and experimental data.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.512-518
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• 2006

In this paper, we investigated the deposition of pentacene thin film on a large area substrate by Organic Vapor Phase Deposition(OVPD) and applied it to fabrication of Organic Thin Film Transistor(OTFT). We extracted the optimum deposition conditions such as evaporation temperature of $260^{\circ}C$, carrier gas flow rate of 10 sccm and chamber vacuum pressure of 0.1 torr. We fabricated 72 OTFTs on the 4 inch size Si Wafer, Which produced the average mobility of $0.1{\pm}0.021cm^2/V{\cdot}s$, average subthreshold slope of 1.04 dec/V, average threshold voltage of -6.55 V, and off-state current is $0.973pA/{\mu}m$. The overall performance of pentacene TFTs over 4 ' wafer exhibited the uniformity with the variation less than 20 %. This proves that OVPD is a suitable methode for the deposition of organic thin film over a large area substrate.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.4
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• pp.551-565
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• 1996

We present the required handover capacity of personal communication service exchange(PCX). We use the flow-based mobility model. The dimension of PCX area and the number of radio port controller(RPC) in a PCX are determined according to the traffic carrying capacity of switching system and RPC. For the rectangular or square-shaped PCX/RPC area and the personal communication service environment with pedestrian traffic, we perform numerical computations to investigate the sensitivity to cell size, portable station(PS) terminating traffic, its density, and its average speed. The results how that the size of PCX/RPC area decreases as the PS terminating traffic and the PS density increase, and the PCX handover capacity required is more than 73,000 in the number of transactions per hour.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.12
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• pp.559-561
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• 2003

We report a new excimer laser annealing method which successfully results in a single grain boundary formation in the channel of polycrystalline silicon thin film transistor. The proposed method is based on lateral grain growth and employs aluminum patterns which act as selective beam mask and lateral heat sink. The maximum grain size obtained by the proposed method is about 1.6${\mu}{\textrm}{m}$ in the length. The grainboundaries should be arranged parallel with the direction of current flow for the best device performance, so we propose a new device fabrication method and a new poly-Si TFT structure. Poly-Si TFT fabricated by the proposed method exhibits considerably improved electrical characteristics, such as high field effect mobility exceeding 240 $cm^2$/Vsec.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.374-374
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• 2010

Charge transfer mechanism of poly(4,4'-aminotriphenylene hexafluoroisopropylidenediphthalimide) (TP6F PI) which exhibits bistable ON and OFF switching has been studied using photoemission electron spectroscopy (PES) and near-edge x-ray absorption fine structure (NEXAFS). Here, we demonstrate novel set-up in which holes are injected by photoemission process instead of direct charge carrier injection via metal electrode. The accumulated charges on the PI surface in the OFF state abruptly flow across the PI film when the bias voltage of a back electrode reaches a specific value, indicating that the film is changed to the ON state. Core level and x-ray absorption spectra probed at charge injection region via photoemission process do not show any evidences implying structural modification of TP6F PI during the phase change. Whereas, in valence band spectra, the highest occupied molecular orbital (HOMO) is shifted toward Fermi level, responsible for improved hole-mobility of TP6F PI of ON state.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.69-72
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• 2018

최근 5G 네트워크의 출현은 전송속도의 진화에 따라 서비스를 확장하고 있는 추세이다. 네트워크에서 사용하는 단말의 수가 증가하며, 단말에서 사용하고 있는 서비스 수는 다양해지고 있다. 이러한 점은 이동성관리 연구가 필수적이며 다양한 기존 연구들이 있다. 하지만 기존 연구에서는 handover delay로 인한 QoE 저하 문제, 활성 링크 수 증가로 인한 패킷 손실 및 네트워크 자원 부족 문제점이 발생을 한다. 이러한 점을 해결하기 위해 단말에서 사용하는 flow 타입을 실시간과 비실시간 서비스로 구별한다. 이동성 요구사항을 필요로 하는 실시간 서비스 앵커를 설정하는 동작과정을 수행하여 라우팅의 경로를 최소화하여 네트워크에서 발생하는 여러 가지 문제점들을 해결한다. 본 논문에서는 수학적 수식을 통한 성능평가를 통해 기존 SDN 기반 이동성관리 보다 제안하는 아이디어가 handover delay 시간을 50% 줄일 수 있다는 점을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.39.2-39.2
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• 2010

In this work we have investigated electrical and optical properties of interface for ITO/Si with shallow doped emitter. The ITO is prepared by DC magnetron sputter on p-type monocrystalline silicon substrate. As an experimental result, The transmittance at 640nm spectra is obtained an average transmittance over 85% in the visible range of the optical spectrum. The energy bandgap of ITO at oxygen flow from 0% to 4% obtained between 3.57eV and 3.68eV (ITO : 3.75eV). The energy bandgap of ITO is depending on the thickness, sturcture and doping concentration. Because the bandgap and position of absorption edge for degenerated semiconductor oxide are determined by two competing mechanism; i) bandgap narrowing due to electron-electron and electron-impurity effects on the valance and conduction bands (> 3.38eV), ii) bandgap widening by the Burstein-Moss effect, a blocking of the lowest states of the conduction band by excess electrons( < 4.15eV). The resistivity of ITO layer obtained about $6{\times}10^{-4}{\Omega}cm$ at 4% of oxygen flow. In case of decrease resistivity of ITO, the carrier concentration and carrier mobility of ITO film will be increased. The contact resistance of ITO/Si with shallow doped emitter was measured by the transmission line method(TLM). As an experimental result, the contact resistance was obtained $0.0705{\Omega}cm^2$ at 2% oxygen flow. It is formed ohmic-contact of interface ITO/Si substrate. The emitter series resistance of ITO/Si with shallow doped emitter was obtained $0.1821{\Omega}cm^2$. Therefore, As an PC1D simulation result, the fill factor of EWT solar cell obtained above 80%. The details will be presented in conference.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.617-624
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• 2015

The conflict of opposing pedestrian traffic-flow in a subway station(made up of stair, passageway, and escalator) diminishes the convenience and mobility of its users. In addition, the station's efficiency would be negatively affected by the growth of delay and queue length in pedestrian facilities. As these phenomena have been resulted by the overlapping in pedestrian's traffic-line, the separation of it would alleviate these problems. For the criteria and methodology of separation, this paper has investigated the bi-directional queue length and delay on the entrance of each facility (stair, passageway and escalator). Since the pedestrian flow exists bidirectionally, we have used the weighted average by inflow rate for the delay value. For the optimization of the separation, the Genetic Algorithm has been utilized in order to minimize the delay.