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V-BLAST OFDM 시스템을 위한 그룹화된 부채널 기반의 간단한 형태의 비트 할당 기법
박대진,양석철,김종원,유명식,이원철,신요안,Park Dae-Jin,Yang Suck-Chel,Kim Jong-Won,Yoo Myung-Sik,Lee Won-Cheol,Shin Yo-An 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.7C
본 논문에서는 V-BLAST(Vertical-Bell labs LAyered Space-Time) 검출기를 사용하는 MIMO-OFDM(Multi Input Multi Output-Orthogonal Frequency Division Multiplexing) 시스템에서, 그룹화된 부채널 기반의 간단한 형태의 비트 할당 기법인 SBA-GS(Simplified Bit Allocation based on Grouped Sub-channels)를 제안한다. 2차원 Water Pouring 원리에 기반하여 MIMO-OFDM 시스템 수신단에서 각 부채널별 비트수 및 전력을 결정하여 궤환하는 일반적인 ABPA(Adaptive Bit and Power Allocation)은 비트오율 측면에서 최적의 성능을 보이지만, 수신단에서 송신단으로의 많은 양의 궤환 정보를 필요로 하고 시스템이 복잡하다는 단점을 가진다. 이러한 단점을 보완하기 위해, 상태가 우수한 각 부채널에 동일한 수의 비트를 할당하여 송신단에서 수신단으로의 궤환 정보량과 시스템 복잡도를 감소시킨 SBA가 제안된 바 있다. 본 논문에서 제안하는 SBA-GS 는 부채널들을 그룹화한 뒤 각 그룹별 부채널들의 펑균 신호대잡음비를 구하여 동일한 변조 방식을 적용하는 SBA를 수행한다. 다양한 차세대 이동통신 채널 환경에서의 모의실험 결과, 지연 확산이 작은 다중 경로 채널의 경우에서는 궤환 정보량을 크게 감소하면서도 SBA와 유사한 결과를 얻을 수 있었 으며, 지연확산이 큰 채널 환경에서는 부채널 그룹화에 따른 BER 성능 열화가 상대적으로 증가하였지만 궤환 정보량 감소와의 절충 관계를 감안할 때 실제 시스템 구현시 고려될 수 있는 우수한 결과를 보임을 확인하였다. In this paper, we present a bit allocation scheme based on grouped sub-channels for MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) systems using V-BLAST (Vertical-Bell laboratories LAyered Space-Time) detector. A fully adaptive modulation and coding scheme may provide optimal performance in the MIMO-OFDM systems, however it requires excessive feedback information. Instead, SBA (Simplified Bit Allocation) scheme for reduction of feedback overhead, which applies the same modulation and coding to all the good sub-channels, may be considered. The proposed scheme in this paper named SBA-GS (Simplified Bit Allocation based on Grouped Sub-channels) groups sub-channels and assigns the same modulation and coding to the set of selected sub-channel groups. Simulation results show that the proposed scheme achieves comparable bit error rate performance of the conventional SBA scheme, while significantly reducing the feedback overhead in multipath channels with small delay spreads.
대량객혈 환자에서 기관지 동맥색전술의 효과; 색전술후 재발의 원인과 예측인자
김병철 ( Byeong Cheol Kim ),김정미 ( Jeong Mee Kim ),김연수 ( Yeon Soo Kim ),김성민 ( Seong Min Kim ),최완영 ( Wan Young Choi ),이경상 ( Kyeong Sang Lee ),양석철 ( Suck Cheol Yang ),윤호주 ( Ho Joo Yoon ),신동호 ( Dong Ho Shin 대한결핵 및 호흡기학회 1996 Tuberculosis and Respiratory Diseases Vol.43 No.4
오광택(Kwang Taek Oh),김연수(Yeon Soo Kim),김병철(Byung Cheol Kim),문두섭(Doo Seop Moon),이동석(Dong Suck Lee),이경상(Kyung Sang Lee),양석철(Suck Chul Yang),윤호주(Ho Joo Yoon),신동호(Dong Ho Shin),박성수(Sung Soo Park),이정희(Jung H 대한내과학회 1996 대한내과학회지 Vol.51 No.5
N/A Objectives: Pulmonary sequestration is a relatively rare congenital anomaly. It is a cystic mass of nonfunctioning lung tissue which lacks an obvious communication with the tracheobronchial tree and which receives all or most of its arterial blood supply from anomalous systemic vessels. It has a wide spectrum of various clinical manifestations. But high index of suspicion of sequestration with the aid of characteristic recurrent and longstanding symptoms, its location and invasive or non-invasive diagnostic tools is the key to early diagnosis and successful treatment. So we performed this clinical study to evaluate clinical symptoms and diagnostic methods of pulmonary sequestration. Methods: We reviewed eight cases of pulmonary sequestration seen during the period from 1982 to 1995 retrospectively to define the anatomical, clinical and radiologic features. Results: 1) The eight cases ranged in age from 11 to 35 years and show an even distribution within age decades. Sex ratio of male to female was a 1:1.67. 2) The presenting complaints were symptoms of local recurrent pulmonary infection. And also revealed unique chest pain or no any symptoms. 3) Plain X-ray findings were solitary nodules in three cases, pneumonic infiltration in two cases and cystic mass with air-fluid level, multiloculated cystic mass and solitary large cystic mass in each of the remaining three cases. 4) Preoperative diagnoses were possible in 5 cases and the other diagnoses were lung cancer in two cases and lung abscess in one case. 5) The seven cases were intralobar type and one case was extralobar type. Their location was in the lower lobe of the lung in seven cases and right upper lobe in one case. Among eight cases, the sequestrated lobe was located bilaterally in one case and the others were located unilaterally with a 2.5:1 Rt/Lt ratio. 6) Associated anomalies were esophageal cyst and bronchogenic cyst in two cases. 7) All cases were treated with lobectomy and extirpation without complication. Conclusion: We reviewed eight cases of pulmonary sequestration and its literature. These data reveal that pulmonary sequestration shows variable but characteristic clinical and radiological features. Therefore, a high index of suspicion about its characteristic clinical and radiologic features can provide us a change of early diagnosis and proper treatment of pulmonary sequestration.
류마티스 관절염환자에서 폐침범의 진단에 있어서 면역학적 지표와 폐기능 검사의 유용성
이동석 ( Dong Suk Lee ),이창범 ( Chang Beom Lee ),고희관 ( Hee Kwan Koh ),문두섭 ( Doo Seop Moon ),이재영 ( Jae Young Lee ),이경상 ( Kyung Sang Lee ),양석철 ( Suck Chul Yang ),윤호주 ( Ho Joo Yoon ),배상철 ( Sang Cheol Bae ),신동 대한결핵 및 호흡기학회 1995 Tuberculosis and Respiratory Diseases Vol.42 No.6