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페이딩 채널환경에서 CDFDM 시스템에 대한 채널 추정과 결합된 심볼검출 방법
조진웅,강철호,Cho, Jin-Woong,Kang, Cheol-Ho The Institute of Electronics and Information Engin 2000 電子工學會論文誌-TC (Telecommunications) Vol.37 No.9
본 논문에서는 페이딩 채널환경에서 COFDM 시스템에 대한 채널 추정과 결합된 심볼 검출 방법에 대해 제안하였다. 제안된 방법은 1) 심볼의 길이에 채널 부호화기의 코드워드 길이를 배합하는 기법과, 2) 세가지 채널 추정 기법과의 조합으로 나타내었다. 첫째 방법은 훈련 신호를 이용한 채널추정 기법과 제안한 심볼 검출 기법을 결합시킨 것이며, 둘째 방법은 첫째 방법에 결정지향 채널추정(Decision-Directed Channel Estimation) 기법을 결합시킨 방법이다. 마지막으로, 근접 부채널간의 AWGN(Additive White Gaussian Noise)의 영향을 줄이기 위해 디인터리브된 평균 채널추정(Averaged Channel Estimation) 기법을 둘째 방법에 결합시켰다. 제안한 3가지 방법들은 영 강압 등화(Zero Forcing Equalizing)방법과 비교하여 커다란 성능 개선 효과가 있음을 컴퓨터 시뮬레이션을 통하여 검증하였다. This paper proposes symbol decoding schemes combined with channel estimation techniques for coded orthogonal frequency division multiplexing (COFDM) systems in fading channels. sThe proposed symbol decoding schemes are consisted of a symbol decoding technique and channel estimation techniques. The symbol decoding based on Viterbi algorithm is achieved by matching the length of branch word from encoder trellis to the codeword length of symbol candidate on decoder trellis. Three combination schemes are described and their error performances are compared. The first scheme is to combine a symbol decoding technique with a training channel estimation technique. The second scheme joins a decision directed channel estimation technique to the first scheme. The time varying channel transfer functions are tracked by the decision directed channel estimation technique and the channel transfer functions used in the symbol decoder are updated every COFDM symbol. Finally, In order to reduce the effect of additive white Gaussian noise (AWGN) between adjacent subchannels, deinterleaved average channel estimation technique is combined. The error performances of the three schemes are significantly improved being compared with that of zero forcing equalizing schemes.
페이딩 채널환경에서 OFDM 시스템에 대한 심볼 검출 및 채널 추정 기법
조진웅,강철호,Cho, Jin-Woong,Kang, Cheol-Ho 대한전자공학회 2001 電子工學會論文誌-TC (Telecommunications) Vol.38 No.3
본 논문에서는 페이딩 채널 환경에서 OFDM 시스템의 채널추정과 심볼 검출이 결합된 방식들을 제안하였다. 제안된 방식들은 결정지향 채널 추정(DDCE) 방식에 근거하여 채널을 추정하며 비터비 알고리즘을 이용한 심볼 검출을 수행한다. 제안된 비터비 결정지향 추정 (VDDCE)방식은 시간상 변화하는 채널을 추척하고 ML 심볼 열을 검출 한다. VDDCE방식에 근거한 순환적 비터비 결정지향(RVDDCE) 방식에서는 복잡도를 줄이기 위해 검출될 심볼 열의 길이를 줄인다. 즉, 훈련 심볼의 간격동안에 채널 추정과 비터비 알고리즘이 일정 간격으로 반복적으로 수행되도록 한다. 또한,AWGN의 효과를 줄이기 위해 평균화 채널 추정(ACE) 방식을 VDDCE와 RVDDCE 방식에 적용하였다. 제안된 방식들은 컴퓨터 시뮬레이션으로 검증하였다. In this paper, we present the joint symbol detection and channel estimation for an orthogonal frequency division multiplexing (OFDM) system in fading channels. The proposed methods are based on decision-directed channel estimation (DDCE) method and their symbol detection is achieved by using Viterbi algorithm. This Viterbi decision-directed channel estimation (VDDCE) method tracks time-varying channels and detects a maximum likelihood symbol sequence. Recursive Viterbi decision-directed channel estimation (RVDDCE) method based on VDDCE method is proposed to shorten the detecting depth. In this method, channel estimate and Viterbi processing are recursively performed every interval of training symbol. Also, average chann'el estimation (ACE) technique to reduce the effect of additive white Gaussian noise (AWGN) is applied VDDCE method and RVDDCE method. These proposed methods arc demonstrated by computer simulation.
콩의 유묘기에 있어서 NaCl Stress 에 의한 생육특성과 광합성 반응
조진웅(Jin Woong Cho),김충수(Choong Soo Kim) 한국환경농학회 1999 한국환경농학회지 Vol.18 No.4
This atudy was conducted to determine the growth characteristics and photosynthesis of soybean (Glycine max L. cv. Keumjongkongl) 30 day old seedling to 100mM NaCl concentration containing 1/2 Hoagland`s nutrient solution in sand culture. The nodule formation of root is not found perfectly with NaCl stress. The leaf dry matter weight (g/plant) of stressed plant is more reduction in 77% to control than any other characters. The water content (%) is tend to increase but water potential (MPa) is tend to decrease at NaCl stress. The chlorophyll content (SPAD) is tend to increase at growing leaf age of control but decrease at NaCl stress. The photosynthesis, stomatal conductance and transpiration are tend to decrease sharply at NaCl stress.
NaCl Stress 에 따른 보리 유묘의 생육특성 및 세포학적 반응
조진웅(Jin Woong Cho),김충수(Choong Soo Kim),이석영(Sok Young Lee),박기선(Ki Sun Park) 한국환경농학회 1998 한국환경농학회지 Vol.17 No.4
This study was conducted to determine the morphological responses of barley seedlings to NaCl stress and to investigate histological changes of cells with transmission electron microscope(TEM) after NaCl stress. Plant height and root length of 10-day old barley seedlings with NaCl stress were reduced and inhibition level was found to be more severe in the plant height than in the root length. The leaf length, leaf width and leaf area were shorter as well with NaCl stress than without NaCl stress. However, there was no difference in the number of roots between NaCl treatments. The weight of dry matter decreased at higher NaCl concentrations, especially at 100mM NaCl. The water content of shoots tend to decrease at higher NaCl concentrations, but there was no difference in the water content of roots, The reduced sugar content was greatly increase than starch. Cellulose content was higher in NaCl stressed-plant than control, and tended to decreased at higher NaCl concentrations. Lignin content also decreased NaCl stressed-plant but there was no tendency at NaCl stress concentrations. Electric conductivity of cell sap with seedlings was high with NaCl stressed-plant. Amount of cell sap gradually increased with time in the roots than in the shoots, The grana of chloroplasts was changed by 150mM NaCl concentration. The christe of mitochondria in root meristematic sells ruined in structure and cell wall of leaf and root was also ruined by NaCl stress.
조진웅(Chin Woong Cho),김병구(Byoung Ku Kim),최수영(Su Young Choi),이태헌(Tae Hun Lee),김미애(Mee Ae Kim),강대송(Dae Song Kang),이순형(Sun Hyoung Lee),김귀완(Kwi Wan Kim),이광민(Kwang Min Lee) 대한내과학회 1995 대한내과학회지 Vol.48 No.6
Primary pulmonary amyloidosis is a rare disorder. It can be classified into tracheo-bronchial, diffuse alveolar septal and nodular parenchymal form. Tracheo-bronchial amyloidosis can be further subdivided into submucosal plaques and pseudotumorial mass. We report a case of pseudotumorial tracheo-bronchial amyloidosis in a 61year-old woman confirmed by bronchofiberscopic biopsy. She has suffered from cough and sputum for 3 months, and recently triangular hazy density in right perihilar area was found on chest X-ray with aggravation of symptoms. The chest CT showed a collapse in superior segment of right lower lobe and pleural thickening with multiple calcifications in posterior pleura of left lower chest. The bronchofiberscopic findings showed that the superior segmental bronchus of right lower lobe was completely obstructed and a solitary mass was in the orifice of right intermedius bronchus. The bronchoscopic biopsy revealed amyloid depositions beneath bronchial mucosa. We discuss this case with review of literature.
NaCl stress 에 의한 몇가지 보리 품종들의 생육시기별 생육 특성
조진웅(Jin Woong Cho),박기선(Ki Sun Park),이석영(Sok Young Lee) 한국환경농학회 2000 한국환경농학회지 Vol.19 No.1
This study was conducted to investigate the growth characteristics of four barley cultivars to NaCl stress of 100mM on 10 March (Tillering stage) and 10 April(Panicle formation stage). Plant grown in Wagner pot(1/5,000 a) with sand culture. Plant height, root length, leaf number and tillering number reduced by NaCl stress and tillering number was shorter than any other character. The reduction of those with NaCl treatment was more severe in 10 March treatment compared to in 10 April it. Leaf, root and straw weight were decreased with NaCl treatment and root weight was more sensitive than any others on 10 March and 10 April treatment. One hundred grain weight (g) in grain component was the most severe in 10 March treatment and panicle number per plant was the most severe in 10 April treatment. The result also varied depending on the cultivars and the time of NaCl stress. In terms of yield component, salt sensitivity was low in order of Bunong, Chalssalbori, Dongbori 1, and Neulssalbori in 10 March and Neulssalbori, Dongbori 1, Bunong and Chalssalbori in 10 April treatment by 100mM NaCl.
HMD착용하고 가상현실 체험 중 현실공간의 물체와의 충돌방지 방법에 대한 연구
조진웅(Jinwoong Cho),고명(Myung Go),홍광민(Kwangmin Hong) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.11
기존 VR기기를 착용하고 플레이를 할 때의 가상 화면은 현실 공간과는 완전히 다른 공간으로 보이기 때문에 현실공간의 물체와 충돌할 위험이 있다. 본 논문은 주변 공간 및 사물을 인식하여 가상현실 속 화면공간에 실시간으로 물체를 감지하여 위험신호를 화면과 소리로 알려주므로, 체험자가 VR기기를 착용하고 체험 할 때 주변 사물과의 충돌을 피할 수 있는 연구를 하였다.