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능동소나 linear frequency modulation 신호의 fractional Fourier transform 분석에 기반한 표적의 거리 추정
형성웅,박명호,황수복,배건성,Hyung, Sungwoong,Park, Myungho,Hwang, Soobok,Bae, Keunsung 한국음향학회 2016 韓國音響學會誌 Vol.35 No.1
Fractional 푸리에 변환(Fractional Fourier Transform : FrFT)은 기존의 푸리에 변환의 일반화된 형태로서, 변환차수 ${\alpha}$에 따라 임의의 시간-주파수 영역에서의 신호해석이 가능하다. FrFT는 특히 LFM(Linear Frequency Modulation) 신호의 분석에 있어 잡음에 강한 특성으로 인해 많은 장점을 가진다. 본 논문에서는 능동소나에서 표적에 맞고 반향된 수신신호의 FrFT 스펙트럼으로부터 표적과의 거리를 추정하는 새로운 방법을 제안하였다. 합성한 표적 신호를 통해 제안한 방법의 타당성을 검증하였으며, 실제 수중 실험을 통해 얻은 잡음 및 잔향 환경에서의 신호에서도 신뢰성 있는 표적과의 거리 추정이 가능함을 확인하였다. As a generalized form of the conventional Fourier transform, fractional Fourier transform (FrFT) can analyze a signal at intermediate domain between time and frequency domains with a transform order ${\alpha}$. Especially, FrFT has a number of advantages in the analysis of LFM (Linear Frequency Modulation) signals due to its robustness to noise. In this paper, we have proposed a new method to detect and estimate the distance of the target from the FrFT spectrum of the received echo signal. Experimental results have validated the proposed method, and shown that reliable target distance could be estimated in noise and reverberation environments.
성김,석호 최,형선 황,Kyung Joong Kim 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.I
Single-, double-, and 50- period SiOx/SiO2 have been prepared on Si wafers by ion beam sputtering deposition and subsequently annealed to form Si nanocrystals (NCs) in the SiOx layer. For 50-period SiOx/SiO2 multilayers, the flat-band voltage shift (VFB) of the C-V curves is found to be inversely proportional to the photoluminescence peak wavelength and intensity, which indicates that larger-sized and more dense Si NCs will exhibit a stronger nonvolatile memory. In single-layer devices, a reduction in the tunnel-oxide thickness strongly enhances VFB, and an asymmetry exists between electron and hole storage. The retention time is improved by increasing the thickness of the tunnel oxide rather than the control oxide. The defect states in these devices are considerably reduced by hydrogenation passivation, enhancing VFB in the hole storage. VFB is enhanced on both polarities by reducing the thickness of the center oxide in doubly-stacked devices. A longer retention time is found in the doubly-stacked memory, which seems to result from suppressed charge leakage between the upper NC layer and the substrate due to an energy barrier in the lower NC layer.
철도역사에서의 교통약자 이용만족도 향상을 위한 지원시스템 설계
황 종 규,김 경 희,안 태 기,이 태 형 대한전기학회 2019 전기학회논문지 P Vol.68 No.1
In case of the railway station where several routes are passing by, it is difficult to find a path wanted by user since it is very complex. Especially in case of the mobility handicapped and for these complex railway stations, it is difficult for them to find a platform, toilet, elevator or any station facilities where they want to go, and it is even more difficult to find an available path including elevator, etc. to reach a platform where they want to go than the general public does. Therefore, it is our actual status that the satisfaction of using railway stations by the mobility handicapped is very low in comparison with that of the general public. Accordingly, this paper proposes the supporting system for the mobility convenience service and its design to provide a system that can guide optimal paths within the railway station through which these mobility handicapped can use railway stations easily and the escort service for the mobility handicapped.