http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
분산 동영상 부호화 시스템을 위한 부호율 적응적인 LDPC 부호 설계
노현우(Hyeun-Woo Noh),이창우(Chang-Woo Lee) 한국방송·미디어공학회 2011 한국방송공학회 학술발표대회 논문집 Vol.2011 No.7
LDPC(low density parity check) 부호는 낮은 복잡성과 Shannon의 한계에 근접하는 오류 정정 능력을 보이기 때문에 turbo 부호와 함께 많은 응용분야에 적용되고 있다. 본 논문에서는 분산 동영상 부호화(distributed video coding: DVC) 시스템을 위한 부호율 적응적인(rate adaptive) LDPC 부호를 설계하기 위하여 패리티 점검 노드를 병합하는 방법을 제안한다. ACE(approximation cycles EMD) 알고리즘을 기반으로 효율적인 LDPC 부호를 설계하고 부호율 적응적인 특성을 갖기 위해 일정한 범위를 지정하고 지정된 범위에 따라 패리티 점검 노드를 병합한다. 그리고 ACE 알고리즘의 계수와 degree distribution을 변화시키면서 성능을 해석한다.
분산 동영상 부호화 시스템을 위한 LDPC 부호 설계 및 성능 평가
노현우(Hyeun-woo Noh),이창우(Chang-woo Lee) 한국통신학회 2012 韓國通信學會論文誌 Vol.37 No.1A
LDPC(1ow density parity check) 부호는 낮은 복잡성과 Shannon의 한계에 근접하는 오류 정정 능력을 보이기 때문에 turbo 부호와 함께 많은 응용 분야에 적용되고 있다. 최근에는 분산 동영상 부호화(distributed video coding: DVC) 시스템의 Wyner-Ziv 프레임 복호를 위해서도 LDPC 부호가 많이 사용되고 있다. 본 논문에서는 DVC 시스템을 위한 LDPC 부호를 설계하기 위해 패리티 체크 행렬 H를 설계하고 부호율 적응적인(rate adaptive) 특성을 만족하기 위해 H 행렬의 패리티 점검 노드를 효율적으로 병합하는 방법을 제안한다. 이를 위해 cycle의 연결성을 고려한 ACE(approximation cycles EMD) 알고리즘을 기반으로 효율적인 LDPC 부호를 설계하고 부호율 적응적인 특성을 갖도록 하기 위해 H 행렬의 크기와 압축율을 고려하여 병합 범위를 지정하고 지정된 범위에 따라 패리티 점검 노드를 병합한다. 그리고 ACE 알고리즘의 계수와 차수 분포를 변화시키면서 설계한 LDPC 부호의 성능을 해석한다. Low density parity check (LDPC) code is widely used, since it shows superior performance close to Shannon limit and its decoding complexity is lower than turbo code. Recently, it is used as a channel code to decode Wyner-Ziv frames in distributed video coding (DVC) system. In this paper, we propose an efficient method to design the parity check matrix H of LDPC codes. In order to apply LDPC code to DVC system, the LDPC code should have rate compatibility. Thus, we also propose a method to merge check nodes of LDPC code to attain the rate compatibility. LDPC code is designed using ACE algorithm and check nodes are merged for a given code rate to maximize the error correction capability. The performance of the designed LDPC code is analyzed extensively by computer simulations.
노현우(Hyunwoo Noh),최승목(Seungmok Choi),민경덕(Kyungdoug Min) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
In this research, the multi-spray-angle nozzle concept was introduced to reduce NOx and PM on Diesel Combustion as improving spray mixing by increasing spatial efficiency. The multi-spray-angle nozzle which has two spray rows was adopted to keep away from effect of plume to plume spray overlap. The single cylinder diesel engine that has piezo common rail injection system was utilized to investigate various types of nozzle. In this research, 9 holes in single-row nozzle as a reference and two of multi-row nozzles which have 10 holes in multi row were investigated. 10holes nozzles have different hole-diameter respectively. Nozzles were verified in various operating conditions that include injection timing, injection pressure, and SCV etc. In this research, rate of heat release was analyzed based on measured cylinder pressure.
노현우(Hyunwoo Noh),조항진(HangJin Jo),유동인(Dong In Yu),박현선(Hyun Sun Park),모리야마 키요후미(Kiyofumi Moriyama),김무환(Moo Hwan Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Pool boiling experiments were conducted on flat and structured SiO₂ surfaces to investigate the effects of surface structures on boiling performances. A micro-structured surface was prepared with the MEMS fabrication methodology, and has regularly distributed micro-scale pillar array. Critical heat flux was enhanced on micro-structured surface up to ~1.7 ㎿/㎡, compared to flat surface with ~0.8 ㎿/㎡. Heat transfer coefficient of the micro-structured surface was higher than that of flat one at high heat flux region, and the difference became larger as applied heat flux increased. Droplet and bubble dynamics were studied and the results presented pinning behavior of liquid film and smaller bubble departure diameters on the micro-structured surface. At high heat flux region, liquid path was observed only on micro-structured surface, which guarantees consistent liquid supply rate to the heating surface.
노현우(Noh, Hyeon Woo),김동주(Kim, Dong Joo) 한국콘크리트학회 2021 한국콘크리트학회 학술대회 논문집 Vol.33 No.2
본 논문에서는 많은 연구자들로부터 조사된 섬유보강 시멘트 복합재료 (Fiber-reinforced cement composites, FRC)의 동적증가계수 (Dynamic increase factor, DIF)를 기반으로 FRC의 DIF 예측 모델을 제안하였다. 본 연구에서 제시된 예측 모델과 유럽콘크리트위원회 (CEB-FIP)에서 제안한 CEB 모델과의 비교 분석을 통해 높은 변형률 속도에서 CEB 모델이 제안한 예측 모델 보다 과대평가되고 있음을 확인하였다. 또한, FRC의 경우 매트릭스 내에 혼입되는 섬유에 따른 미세균열의 생성과 확장이 하중 조건 하에서 DIF에 영향을 미치는 것으로 조사되었다. In this paper proposed a dynamic increase factor (DIF) prediction model for fiber-reinforced cement composites (FRC). Comparative analysis with the proposed prediction model and the most widely adopted DIF prediction model of concrete proposed by the European Committee for Concrete (CEB) confirms that the CEB prediction model is overestimated than the DIF prediction model of FRC at high strain rates. Moreover, in case of FRC, it was investigated that the occurrence and expansion of micro cracks due to the fibers contained to matrix, unlike normal concrete, affect DIFs under loading conditions.
접촉각에 따른 기포 직경 및 임계열유속 변화에 관한 연구
노현우(Hyunwoo Noh),조항진(HangJin Jo),김설하(Seol Ha Kim),박현선(Hyun Sun Park),김무환(Moo Hwan Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
A pool boiling experiment was conducted to investigate the relation among contact angle, bubble diameter, and critical heat flux. Infrared(IR) thermometry was employed to measure the bubble diameter directly in pool boiling experiment conducted on Si and Teflon surface by visualizing the liquid-vapor interface through IR-transparent silicon substrate. Critical heat flux on Si and Teflon surface were about 1,200kW/m² and 160kW/m², respectively. It was observed that bubble behaviors, i.e., nucleation site density, bubble frequency, and bubble diameter, were drastically changed with respect to contact angle conditions at the same heat flux condition. The bubble diameter decreases as the applied heat flux increases and as contact angle decreases.