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레이더 센서 장착 자동차의 전방충돌경고·보호 장치 오작동 시험 분석 연구
박지양(Jiyang Park),권영문(yeongmun Gwon),정재환(Jaehwan Jeong),나대영(Daeyoung Ra),박상협(Sanghyeop Park),이효열(Hyoyeol Lee),최수광(Sookwang choi) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6
Advanced device-equipped Vehicles are actively developed and legislation is underway around the world. As a result, Automobile manufacturers and others aim to continue research on high-tech devices and develop high-performance devices. These state-of-the-art vehicles are the most basic devices of autonomous vehicles. The automobile industry is progressing very quickly, but the number of malfunctions in high-tech devices is also increasing. In particular, in the case of Autonomous Emergency Braking(AEB), it is essential to lead to an Accident when a malfunction occurs. Typical high-tech devices include camera sensors and radar sensors. Both sensors are connected and operated, but radar sensors are mainly longitudinal and camera sensors are mainly lateral. Accordingly, this study analyzes AEB devices that can cause accidents when malfunctioning, it deliberately malfunctions the highly relevant radar sensor to determine to what extent the radar sensor’s performance persists. We want to analyze the risk of malfunction and the limitations of radar sensors through comparative analysis with existing automobile manufacturing standards and CAN data.
Hwang, Younghun,Um, Youngho,Park, Hyoyeol Springer 2012 Nanoscale research letters Vol.7 No.1
<P>In this paper, we report a systematic investigation of band-edge photoluminescence for Cd<SUB>1-<I>x</I></SUB>Mn<I><SUB>x</SUB></I>Te crystals grown by the vertical Bridgman method. The near-band-edge emissions of neutral acceptor-bound excitons (labeled as L1) were systematically investigated as a function of temperature and of alloy composition. The parameters that describe the temperature variation of the energy were evaluated by the semiempirical Varshni relation. From the temperature dependence of the full width at half maximum of the L1 emission line, the broadening factors <I>Γ</I>(<I>T</I>) were determined from the fit to the data. The activation energies of thermal quenching were obtained for the L1 peak from the temperature dependence of the bound exciton peaks and were found to decrease with increasing Mn concentration.</P>
황영훈,Youngho Um,Hyekyeong Kim,Hyoyeol Park,Sunglae Cho 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
We investigated the magneto-optical properties of diluted magnetic semiconductor Cd$_{0.63-y}$ Mn$_{0.37}$Co$_{y}$Te single crystals grown using a vertical Bridgman method. From the temperature dependence of the band-gap energy, the Varshni temperature parameter $\alpha$ was found to increase linearly with increasing Co concentration $y$ while $\beta$ decreased with $y$. The Faraday rotation as a function of photon energy with various Co compositions for CdMnCoTe in the temperature range of 10 to 300 K was measured. The Verdet dispersion curves were enhanced near the fundamental band gap energy. The Verdet constant becomes larger since because the effect of the $sp$-$d$ exchange interaction is enhanced as the temperature is lowered. At 10 K, the Verdet constants of the Faraday rotation for the samples with $y$ = 0, 0.01, 0.02, and 0.04 were observed to be --0.94, --1.41, --1.69, and --2.11 deg/G cm at 610 nm, respectively. The Verdet constant showed a maximum for the sample with $y$ = 0.04, and the value was approximately 2.3 times larger than that of the Cd$_{0.63}$Mn$_{0.37}$Te crystal. The Faraday rotation increased as Co content was increased, and the origin of the enhancement of the Faraday rotation in CdMnCoTe crystals could be explained in terms of the magnetization.
Optical, Electrical, and Magneto-Optical Properties for Bulk Cd0.63-yMn0.37HgyTe Single Crystals
황영훈,Youngho Um,Hyekyeong Kim,Hyoyeol Park,Sunglae Cho 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
We investigated the magneto-optical properties of diluted magnetic semiconductor Cd$_{0.63-y}$ Mn$_{0.37}$Hg$_{y}$Te single crystals grown using a vertical Bridgman method. This material crystallizes in the zinc-blende structure for values of $y$ $\leq$ 0.07. The band gap energy increases with increasing for $y$ $\leq$ 0.03, while decreasing with increasing for $y$ $\geq$ 0.03. An anomalous behavior was also observed in the magnetic susceptibility and the electrical resistivity. The Verdet dispersion curves were enhanced near the fundamental band gap energy. The Verdet constant showed a maximum for the sample with $y$ = 0.03, and the value was approximately four times larger than that of the Cd$_{0.63}$Mn$_{0.37}$Te crystal. The Verdet constant had a maximum around Hg compositions with $y~\sim$ 0.03, and this result agrees well with the behavior of the magnetic susceptibility. This result reflects that Hg ion mediates and enhances the spin-spin interaction between Mn$^{2+}$ ions with increasing Hg composition up to $y~\sim$ 0.03.
신유리미,황영훈,엄영호,Duong Anh Tuan,조성래,Hyoyeol Park 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.6
Here, we report on the structural and the optical properties of polycrystalline NiO thin filmsprepared by using the thermal oxidation of metallic Ni. After the deposition of the Ni films, theywere placed in a thermal oxidation furnace at different temperatures (400, 500, 600, 700, and 1000C), resulting in mean crystallite sizes between 6 nm and 40 nm. From the optical absorptionspectra, we determined the energy gaps of these films. Interestingly, the energy gaps were in therange of 3.13 3.29 eV, which were smaller than those of the bulk.
Spectral Dependence of the Dielectric Function of Quaternary CdMnCoTe by Spectroscopic Ellipsometry
황영훈,Youngho Um,Hyekyeong Kim,Hyoyeol Park 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.III
Spectroscopic ellipsometry measurements of the complex dielectric function of a series of Cd$_{0.63-y}$Mn$_{0.37}$Co$_y$Te single crystals grown by the vertical Bridgman method have been performed in the 1.5 $\sim$ 5.5 eV energy range at room temperature. The measurement data were analyzed by fitting the second-derivative spectra ($d^2 \varepsilon$/$d \omega^2$) with a theoretical model, namely, the standard critical-point (SCP) line shapes. The $E_1$, $E_1$+$\Delta_1$ and $E_2$ energies decreased with increasing Co composition $y$, which is due to the hybridization effect of the valence and conduction bands in Cd$_{1-x}$Mn$_x$Te with Co $3d$ levels.
Faraday Rotation of Diluted Magnetic Semiconductors Cd₁-x-yMnxHgyTe Single Crystals
황영훈(Younghun Hwang),김혜경(HyeKyeong Kim),엄영호(YoungHo Um),박효열(Hyoyeol Park),진광수(Gwangsoo Jeen) 한국자기학회 2004 한국자기학회 학술연구발표회 논문개요집 Vol.14 No.2
Cd_(1-x-y)Mn_xHg_yTe single crystals were grown by using the vertical Bridgman method. The Verdet constant was evaluated as a function of the photon energy by using the result for the Faraday rotation. Th Verdet curve was well fitted by using a single-oscillator method and shifted downward at y≥0 due to the exchange interaction. The Faraday rotation decreased linearly with increasing magnetic field from 0 KG to 8 KG.
Electronic and optical properties of layered chalcogenide FeIn2Se4
Younghun Hwang,Jeongyong Choi,Yang Ha,Sunglae Cho,Hyoyeol Park 한국물리학회 2020 Current Applied Physics Vol.20 No.1
We investigated the spectral-dependent dielectric function and temperature-dependent bandgap energy of layered chalcogenide FeIn2Se4 crystals. The critical-point energy and Lorentzian broadening were analyzed by fitting second-derivative spectra using the standard critical point model. The temperature effect of the bandgap energy was analyzed based on an analytical model considering both thermal lattice expansion and electron– phonon interactions. We also extensively analyzed the temperature dependence of absorption tails and identified their possible origins. The dielectric functions and absorption coefficient in the photon-energy range of 0.75–4.75 eV were obtained. The results also showed that optical phonon modes associated with the electron– phonon interactions could be closely related to the average phonon energy.