• 소성∙가공
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• 제21권4호
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• pp.221-227
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• 2012

The automotive and electronic industries have seriously considered the use of magnesium alloys because of their excellent properties such as strength to weight ratio, EMI shielding capability, etc. However, it is difficult to form magnesium alloys at room temperature because of the mechanical deformation related to twinning. Hence, magnesium alloys are normally formed at elevated temperatures. In this study, a temperature dependent constitutive model, the C-H/V model, for the magnesium alloy AZ31B sheet is proposed. A hardening law based on nonlinear kinematic and H/V(Hollomon/Voce) hardening model is used to properly characterize the Bauschinger effect and the stabilization of the flow stress. Material parameters were determined from a series of uni-axial cyclic experiments(C-T-C) with the temperature ranging between 150 and $250^{\circ}C$. The developed models are fit to experimental data and a comparison is made.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.4-7
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• 2002

Samples of $Nb/Al-AlO_x/Nb$ tunnel junction with the size of $50 ${\mu}{\textrm}{m}$ {\times} 50 ${\mu}{\textrm}{m}$$ were fabricated by using self-aligning and reactive ion etching technique In the high quality samples, the $V_m$ value (the product of the critical current and subgap resistance measured at 2 mV) was 34 mV at the critical current density of $J_c: 500 A/cm^2 and the V_g$ value (the gap voltage) was 2.8 mV. For the higher $J_c$ sample, voltage fluctuation at the gap voltage was observed. The $V_m and J_c$ values for this sample were 8 mV and 900 A/cm$^2$, respectively. Also, the relationship between critical current density $J_c$ and specific normal conductance $G_s$ of the junctions with $J_c$ in the range of 28 A/cm$^2$~940 A/cm$^2$was investigated.

• 한국표면공학회지
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• 제39권3호
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• pp.87-92
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• 2006

The characteristic of interface layer and the effect of bias voltage on the microstructure of c-BN films were studied in the microwave plasma hot filament C.V.D process. c-BN films were deposited on a high speed steel(SKH-51) substrate by hot filament CVD technique assisted with a microwave plasma to develop a high performance of resistance coating tool. c-BN films were obtained at a gas pressure of 20 Torr, vias voltage of 300 V and substrate temperature of $800^{\circ}C$ in $B_2H_6-NH_3-H_2$ gas system. It was found that a thin layer of hexagonal boron nitride(h-BN) phase exists at the interface between c-BN layer and substrate.

• 한국재료학회지
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• 제5권8호
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• pp.1020-1025
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• 1995

Au/Si(100) Schotty diode를 l00k~300k 온도범위에서 current voltage(I-V), capacitance-voltage(C-V)측정을 하였다. 얻어진 Schottky barrier height(SBH)갑은 실온에서 두측정값 모두 (0.79$\pm$0.02)eV 이다. 그러나 온도가 감소할수록 I-V측정에서 SBH는 선형적으로 감소하고 C-V측정에서 SBH는 온도에 따른 변화가 관찰되지 않았다. 이것은 낮은 온도에서 열이온 방출 이론을 따르지 않는다는 것을 나타낸다. 이것으로 재결합 전류를 고려하여 계산해 본 결과 I-V에서도 SBH의 변화가 관찰되지 않으므로 C-V측정과 일치됨을 보았다. 이런 상반된 결과를 가져오는 이유는 전류수송현상이 온도에 따라 변화하므로 생긴 것임을 알 수 있었다.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.18-21
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• 1991

청록색 영역에서 발진하는 XeF(C$\longrightarrow$A)엑사이머 레이저 여기용 2.56MeV 전자빔 가속기를 개발하였다. 대출력 전자빔 가속기는 $\pm$80kV로 충전하는 Marx Generator를 동축구조로 꾸밈으로서 낮은 임퍼던스와 인덕턴스를 유지할 수 있었고, 빠른 전압상승과 유사구형파 출력을 얻을 수 있었다. 본 연구에서는 대출력 전자빔가속기 (2.56 MeV, 2.2KJ)의 파라메터와 동작특성, 전압측정 등을 기술한다.

• 한국전자파학회논문지
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• 제12권6호
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• pp.890-898
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• 2001

Modified Materka-Kacprzak 대신호 MESFET(Metal Semiconductor Field Effect Transistor) model을 사용하여 4H-SiC MESFET의 대신호 모델링을 수행하였다. Silvaco사의 소자 시뮬레이터인 ATLAS를 사용하여 4H-SiC MESFET 소자 시뮬레이션을 수행하고, 이 결과를 modified Materka 대신호 모델을 사용하여 모델링 하였다. 시뮬레이션 및 모델링 결과는 -8 V의 pinch off 전압과 $V_{GS}$ =0 V, $V_{DS}$ =25 V에서 $I_{DSS}$270 mA/mm, $G_{m}$ =52.8 ms/mm를 얻을 수 있었고, 전력 특성 시뮬레이션을 통해 2GHz, $V_{GS}$ =-4V, $V_{DS}$ =25 V에서 10dB의 Gain과 34dBm(1 dB compression point)의 출력전력, 7.6W/mm의 전력밀도, 37%의 PAE(power added efficiency)를 얻을 수 있었다.다.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3248-3252
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• 2012

Vibrio extracellular metalloprotease (vEP), secreted from Vibrio vulnificus, shows various proteolytic function such as prothrombin activation and fibrinolytic activities. Premature form of vEP has an N-terminal (nPP) and a C-terminal (C-ter100) region. The nPP and C-ter100 regions are autocleaved for the matured metalloprotease activity. It has been proposed that two regions play a key role in regulating enzymatic activity of vEP. Especially, C-ter100 has a regulatory function on proteolytic activity of vEP. C-ter100 domain has been cloned into the E. coli expression vectors, pET32a and pGEX 4T-1 with TEV protease cleavage site and purified using gel-filtration chromatography followed by affinity chromatography. To understand how C-ter100 modulates proteolytic activity of vEP, structural studies were performed by heteronuclar multi-dimensional NMR spectroscopy. Backbone $^1H$, $^{15}N$ and $^{13}C$ resonances were assigned by data from standard triple resonance and HCCH-TOCSY experiments. The secondary structures of vEP C-ter100 were determined by TALOS+ and CSI software based on hydrogen/deuterium exchange. NMR data show that C-ter100 of vEP forms a ${\beta}$-barrel structure consisting of eight ${\beta}$-strands.

• 자동차안전학회지
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• 제15권3호
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• pp.34-42
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• 2023

Simulation-based virtual testing is known to be a major requirement for verifying the safety of autonomous driving functions. However, in the simulation environment, there is a difficulty in that all driving environments related to the autonomous driving system must be realistically modeled. In particular, C-ITS (Cooperative-Intelligent Transport Systems) is essential for urban autonomous driving of Lv.4, but the approach to modeling for C-ITS service in the MILS (Model in the Loop Simulation) environment is not yet clear. Therefore, this paper aims to deal with V2X (Vehicle to Everything) modeling methods to effectively apply C-ITS-based autonomous cooperative driving services in the MILS environment. First, major C-ITS services and use cases for autonomous cooperative driving are analyzed, and a modeling method of V2X signals for C-ITS service simulation is proposed. Based on the modeled V2X messages, the validity of the proposed approach is reviewed through simulations on the C-ITS service use case.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.63-63
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• 2009

In this work, we demonstrate 800V 4H-SiC power DMOSFETs with several structural alterations to observe static DC characteristics, such as a threshold voltage ($V_{TH}$) and a figure of merit ($V_B^2/R_{SP,ON}$). To optimize the static DC characteristics, we consider four design parameters; (a) the doping concentration ($N_{CSL}$) of current spreading layer (CSL) beneath the p-base region, (b) the thickness of p-base ($t_{BASE}$), (c) the doping concentration ($N_J$) and width ($W_J$) of a JFET region, (d) the doping concentration ($N_{EPI}$) and thickness ($t_{EPI}$) of epi-layer. Design parameters are optimized using 2D numerical simulations and the 4H-SiC DMOSFET structure results in high figure of merit ($V_B^2/R_{SP,ON}$>~$340MW/cm^2$) for a power MOSFET in $V_B{\sim}1200V$ range.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.236-236
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• 2009

This paper describes the fabrication and characteristics of Schottky micro hydrogen sensors for high temperatures by using polycrystalline(poly) 3C - SiC thin film grown on Si substrates with thermal oxide layer using APCVD. Pd/poiy 3C-SiC Schottky diodes were made and evaluated by I-V and C-V measurements. Electric current density and barrier height voltage were $2\times10^{-3}\;A/cm^2$ and 0.58 eV, respectively. These devices could operate stably at about $400^{\circ}C$. According to $H_2$ concentrations, their barrier height($\Phi_{Bn}$) were changed 0.587 eV, 0.579 eV, 0.572 eV and 0.569 eV, respectively. the current was increased. Characteristics of implemented sensors have been investigated in terms of sensitivity, linearity of response, response rate and response time. Therefore, from these results, Pd/poly 3C-SiC Schottky devices have very high potential for high temperature chemical sensor applications.