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1/<i>f</i> noise characteristics of AlGaN/GaN HEMTs with periodically carbon-doped GaN buffer layer
Im, Ki-Sik,Choi, Jinseok,Hwang, Youngmin,An, Sung Jin,Roh, Jea-Seung,Kang, Seung-Hyeon,Lee, Jun-Hyeok,Lee, Jung-Hee Elsevier 2019 MICROELECTRONIC ENGINEERING Vol.215 No.-
<P><B>Abstract</B></P> <P>We investigate the DC and 1/<I>f</I> noise properties in Al<SUB>0.25</SUB>Ga<SUB>0.75</SUB>N/GaN high-electron mobility transistors (HEMTs) with two types of 2 μm-thick periodically carbon-doped GaN buffer layer (PC-doped GaN buffer) with and without inserting the 30 nm-thick Al<SUB>0.05</SUB>Ga<SUB>0.95</SUB>N back barrier layer between the GaN channel layer and the PC-doped GaN buffer. The PC-doped GaN buffer layer consists of multiple layers of 12 nm-thick C-doped GaN layer with doping concentration of 1 × 10<SUP>18</SUP> cm<SUP>−3</SUP> and 50 nm-thick undoped GaN layer with unintentional n-typing concentration of 2 × 10<SUP>16</SUP> cm<SUP>−3</SUP>. A reference AlGaN/GaN HEMT with 2 μm-thick highly-resistive GaN buffer layer without C-doping is also fabricated for comparison. Similarly to the reference AlGaN/GaN HEMT, the AlGaN/GaN HEMTs with PC-doped GaN buffer show typical 1/<I>f</I> noise characteristics mainly due to the trapping effects at the AlGaN/GaN interface from subthreshold region to strong-accumulation region, which indicates that the deep trapping effects in the PC-doped GaN buffer layer is negligible, and experience the correlated mobility fluctuations (CMF), which is convinced from the drain current power spectral density (PSD) versus drain current. At off-state (deep-subthreshold region), on the other hand, the HEMTs with the PC-doped GaN buffer layer exhibit 1/<I>f</I> <SUP>2</SUP> noise characteristics, which are closely related to the generation-recombination (g-r) noise caused by the spatial trapping/detrapping process between the deep acceptor in the C-doped layer and the shallow donor in the undoped layer in the PC-doped GaN buffer, while the reference HEMT still shows typical 1/<I>f</I> noise characteristics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Noise characteristics in AlGaN/GaN HEMTs with/without PC-doped buffer layer were investigated. </LI> <LI> PC-doped buffer layer consists of 12 nm-thick carbon-doped GaN and 50 nm-thick un-doped GaN. </LI> <LI> All devices exhibited 1/<I>f</I> noise properties and CMFs from subthreshold to strong-accumulation. </LI> <LI> At off-state, PC-doped buffer devices exhibited 1/<I>f</I> <SUP>2</SUP> noise properties at frequency > 40 Hz. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
라즈베리파이와 OCR기반의 포터블 차량 번호판 인식기 모듈 개발에 관한 연구
권혁호 ( Hyeok-ho Kwon ),박성현 ( Sung-hyun Park ),임준호 ( Jun-ho Im ),장성원 ( Sung-won Jang ),곽태원 ( Tae-won Kwak ) 한국정보처리학회 2019 한국정보처리학회 학술대회논문집 Vol.26 No.2
이 모듈은 오픈소스인 Tesseract OCR 및 Open CV 라이브러리와 Raspbeny Pi를 사용하여 저렴한 비용으로 구현합니다. 컴팩트한 사이즈로 사람이 직접 들고 움직이면서도 사용이 가능하며 사용자의 니즈에 따라서 한 곳에 위치하여도 사용 가능합니다. Open CV 라이브러리를 사용하여 이미지 이진화, 노이즈 필터링 후에 흑백 이미지를 만들고 윤곽선 검출 알고리즘을 통해서 번호판 영역을 추출하여 Tesseract OCR 엔진을 사용해서 차량 번호판이 추출된 이미지에서 차량 번호를 인식 합니다. 인식된 번호는 Tkinter 와 Python, 데이터베이스를 활용하여 구현된 GUI프로그램을 통해서 유료주차장(선불, 후불) 또는 아파트에서 사용할 수 있는 주차장 관리 서비스를 함께 제공합니다.