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제한된 되먹임의 송신 빔성형 MIMO OFDM 시스템에서 PAPR 감소 기법
신준우,정의림,이용훈,Shin, Joon-Woo,Jeong, Eui-Rim,Lee, Yong-Hoon 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.8c
높은 주파수 효율 때문에 무선 통신에 널리 쓰이고 있는 직교 주파수 분할 다중화 방식의(orthogonal frequency division multiplexing: OFDM) 문제점 중 하나는 높은 첨두대평균 전력비(peak to average power ratio: PAPR) 이다. 본 논문에서는 제한된 되먹임 정보를 가지는 송신 다중 안테나(multiple input single output: MISO) 빔성형 OFDM(beamforming OFDM) 시스템을 위한 PAPR 감소 기법을 제안한다. 제안된 방식은 채널의 영공간(null space)에서 생성된 부가신호를 원 신호에 더하여 PAPR을 줄이는 방법에 기반한다. 먼저 전체 채널 되먹임을 가정한 기존의 시스템을 부분 채널 정보 되먹임 시스템에 적용할 때의 문제점을 파악하고, 이를 바탕으로 수신 성능 열화를 줄이면서 PAPR을 감소시키는 부가 신호에 대한 가중 함수를 제안한다. 가중 함수는 수치적으로 구하며 컴퓨터 모의 실험을 통해 제안된 방식이 비트오류율(bit error rate: BER) 성능 손실은 거의 없으면서 2.5dB 정도의 PAPR감소 효과를 얻을 수 있음을 보인다. High peak-to-average power ratio(PAPR) is one of serious problems in the orthogonal frequency division multiplexing(OFDM) systems. This paper proposes a PAPR reduction technique for limited feedback multiple input multiple output(MIMO) OFDM systems. The proposed method is based on the null space of the MIMO channel where a dummy signal is made in the channel's null space and then, subtracted from the original signal to reduce the PAPR. First, we show that a problem occurs when the existing method is directly applied to limited feedback MIMO case. Then, a weight function for the dummy signal is proposed to mitigate the degradation of the receiver performance while still reducing PAPR significantly. The weight function is derived from a constrained nonlinear optimization problem to minimize the mean square error between the received signal and its ideal signal. Simulation results shows that the proposed technique provides about 2.5dB PAPR reduction with 0.2dB bit-error probability loss.
신준우(Joon-woo Shin),이진석(Jin-seok Lee),이중만(Jung mann Lee) 한국기술혁신학회 2009 기술혁신학회지 Vol.12 No.1
본 논문은 효율적인 IT고급인력양성정책 추진을 위하여 IT고급인력을 정의하고, 지금까지 추진되어온 정부의 IT고급인력양성 정책의 변천과정을 살펴보았다. 또한 국내외의 고급인력양성정책 비교 및 문제점을 분석하여 미래지향적 IT고급인력양성 정책방향을 설정 하였다. 이를 위해 IT분야 국가 R&D로드맵과 연계한 고급인력양성체계 구축, 공급확대 유지 및 글로벌 경쟁력을 배양하는 고급인력양성으로의 비전 전환, IT기반 융합인력양성으로의 범위 확대, R&D연계형 인력양성사업의 성과제고를 위한 연구방향의 명확화 등 4가지 기본방향과 이에 따른 세부추진 방향을 제시하였다. This study attempts to define IT high-level human resources and to investigate past IT high-level human resources development (HRD) policies in order to promote IT HRD policy efficiently. Benchmarking implications were derived from comparative studies of foreign high-level HRD policies and we suggest IT high-level HRD Policy in the framework of National Future Strategy. The results of this study are rich in implications for implementation of IT HRD related to national R&D road-map in the field of information technology, the supply spread maintenance and the vision change of high-level HRD to cultivate global competitiveness, IT-based Fusion Technology HRD, and R&D related HRD policies and action plans.
김동수,최혁원,신준우,문상웅,김재석,이주화.Dong Su Kim. M.D.. Hyuk Won Choi. M.D.. Joon Woo Shin. M.D.. Sang Woong Moon. M.D.. Jae Suk Kim. M.D.. Joo Wha Lee. M.D. 대한안과학회 2007 대한안과학회지 Vol.48 No.3
Purpose: There has not been any reports of Ralstonia paucula causing any ophthalmologic disease. However, we have detected Ralstonia paucula in the lens washing agents of a corneal ulcer patient wearing contact lens. Methods: A 26-years-old female patient was admitted to our hospital complaining of loss of visual acuity and hyperemia. Slit lamp biomicroscopy and smear culture was done to the anterior segment of the eye and the lens cleansing agent. The patient was treated with antibiotic eye drop and intravenous antibiotic medication. Results: The results of both smear and culture showed the presence of Ralstonia pacula and responded well to antibiotics treatment with ceftazidime.
개방각녹내장환자의 황반 망막 및 시신경유두주위 망막신경섬유층 두께와 시야변화와의 상관관계
정원도,이동은,이주화,신준우,Won-Do Jeong,Dongeun Lee,Joo-Hwa Lee,Joon-Woo Shin 대한안과학회 2009 대한안과학회지 Vol.50 No.2
Purpose: This study was performed to evaluate the macular and peripapillary retinal nerve fiber layer (RNFL) thickness and to evaluate their association with glaucomatous visual field change. Methods: Forty normal eyes of 24 subjects, 30 ocular hypertension eyes of 15 patients, 30 pre-perimetric glaucoma eyes of 18 patients and 90 open angle glaucoma eyes of 59 patients. The macularand peripapillary RNFL thickness were measured by the optical coherence tomography (Stratus OCTTM model 3000, Carl Zeiss Meditec) and visual field tests were performed by the Humphrey's automated perimetry. Results: There was a significant decrease of both the macular (p<0.05) and peripapillary RNFL thickness (p<0.001) in the open angle glaucoma group compared with the normal group. In 190 eyes, statistically significant positive relationship was demonstrated between mean deviation (MD) and all areas of peripapillary RNFL thickness (p<0.001) as well as between MD and all areas of macular thickness except the fovea, central ring (p<0.01). Conclusions: The macular and peripapillary RNFL thickness were significantly decreased and the findings indicated a significant association with the visual field change in open angle glaucoma eyes.