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대용량 다중 입력 다중 출력 시스템에서 코드북 갱신 기반의 새로운 계층적 다중 빔 검색 방법
윤성근(Sung-Geun Yoon),이승준(Seung Joon Lee) 한국정보기술학회 2020 한국정보기술학회논문지 Vol.18 No.1
In this paper, a hierarchical codebook based multi-beam search is studied for multiple stream transmission in the massive MIMO systems. For the multi-beam search where multiple beams are serially searched, it is important that the effect of the already selected beams on each beam should be considered in searching for the next beams. A recently reported scheme for considering the effect of the already selected beams is reviewed and its limitation is investigated. A new hierarchical codebook-based multi-beam search scheme using a codebook update is proposed so as to mitigate that limitation. Computer simulation results are presented to verify that the proposed scheme outperforms the conventional one.
윤성근(Sung-Geun Yoon),이승준(Seung Joon Lee) 한국정보기술학회 2020 한국정보기술학회논문지 Vol.18 No.2
The characteristics and demerits of the conventional hierarchical codebooks are investigated, which have been reported for an efficient beam search in millimeter wave massive multi-input multi-output systems. The followings are required for desirable hierarchical codebooks: every codeword should have constant modulus entries for feasible implementation, every codeword should force all the antenna elements to be active for preventing from total antenna power loss, and neighboring codeword beams should have no interference with each other for high SNR. However there is no conventional scheme satisfying all the requirements. In this paper, the gradient descent method, which is one of the iterative optimization approaches, is applied to derive the codebook meeting all the requirements. It is confirmed by computer simulations that the codebook obtained by the proposed method has larger achievable data rates than the conventional ones.
작열통환자에서 Morphine을 이용한 성상신경절 차단 효과
김은미(Eun Mi Kim),윤성근(Sung Geun Yoon),박명혜(M 대한통증학회 1998 The Korean Journal of Pain Vol.11 No.1
The sympathetic nervous system has been implicated as an important factor contributing to causalgia. Basis on reports of presence of opioid receptors in sympathetic autonomic ganglia, including human stellate ganglion, we administered morphine in stellate ganglion block for a patient with causalgia. The patient suffering from brachial plexus injury treated with stellate ganglion block in conjunction with physical therapy. Stellate ganglion block was performed in a paratracheal approach by injection of 1% lidocaine, or 0.25% bupivacaine 8 ml, with morpine 1 mg. Patients symptoms were dramatically improved after 13 stellate ganglion blocks.