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공간다중화 MIMO 시스템을 위한 MML-DFE기법의 FPGA 구현
임태호,이규인,박창환,정기철,유성욱,김재권,조용수,Im, Tae-Ho,Lee, Kyu-In,Park, Chang-Hwan,Jeong, Ki-Cheol,Yu, Sung-Wook,Kim, Jae-Kwon,Cho, Yong-Soo 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.11A
ML-DFE(Maximum Likelihood-Decision Feedback Equalization) 기법은 V-BLAST와 같은 공간다중화 MIMO시스템에서 ML 기법의 구현 복잡도를 줄이기 위한 준 최적 신호검출기법으로 불 수 있다. ML-DFE 기법은 ML 기법과 DFE 기법을 결합하여 오차전파를 줄이면서 rich scattering 환경에서 높은 다이버시티 이득을 얻을 수 있다. 본 논문에서는 ML-DFE 기법과 동일한 성능을 보이면서 연산복잡도를 줄일 수 있는 MML-DFE(Modified Maximum Likelihood - Decision Feedback Equalization) 기법을 제안한다. 또한 FPGA 구현을 통하여 제안된 MML-DFE 기법이 기존 ML-DFE 기법에 비하여 구현복잡도를 크게 감소시키면서 동일한 성능을 유지함을 확인한다. The ML-DFE(Maximum Likelihood-Decision Feedback Equalization) can be viewed as either a suboptimal signal detection method for reducing hardware complexity of ML or an enhanced detection method for reducing the effect of error propagation of SIC(Successive Interference Cancellation) in spatially multiplexed MIMO systems such as V-BLAST. The ML-DFE can achieve a higher diversity in rich scattering environments as well as reducing the error propagation effect by combing ML decoding with the DFE. In this paper, an MML-DFE(Modified Maximum Likelihood-Decision Feedback Equalization) is proposed to reduce the hardware complexity of the ML-DFE, without compromising performance. It is shown by FPGA implementation that the proposed MML-DFE can achieve the same performance as the ML-DFE with significantly reduced hardware complexity.
B와 W의 함량이 무전해 Co 합금 박막의 경도에 미치는 영향 연구
임태호,김재정 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.6
In this study, the electroless deposition of Co-B and Co-W-B alloy thin films was developed and the effect of B and W contents on the hardness of the alloy thin films were investigated. An amorphous Co alloy film was successfully formed by electroless deposition and the contents of B and W in the film were controlled by varying the concentrations of dimethylamine borane and sodium tungstate dihydrate, which were used as a reducing agent and W source, respectively. The hardness of the thin films increased as the contents of B and W were increased because B and W act as impurities suppressing the propagation of dislocation in a film. In addition, it was found that the content of B and W in the Co alloy films can be increased significantly when aeration is not performed. Finally, the hardness of Co- W-B alloy thin film was improved up to 8.9 (±0.3) GPa. 본 연구에서는 Co-B, Co-W-B 합금 박막 형성을 위한 무전해 전착법을 고안하고, 이를 통해 형성한 합금 박막의 B과W의 함량이 박막의 경도에 미치는 영향을 살펴보았다. 무전해 전착을 통해 무정형 상태의 Co 합금 박막을 성공적으로형성할 수 있었으며, 환원제인 dimethylamine borane과 W의 원료인 sodium tungstate dihydrate의 농도를 조절함으로써Co 합금 박막 내 혼합되는 B과 W의 함량을 조절하였다. 이를 통해 Co 합금 박막 내 전위(dislocation)의 전파(propagation)를 억제하는 B과 W의 함량이 증가할수록 박막의 경도가 증가함을 확인할 수 있었다. 뿐만 아니라, 무전해 전착 시 포기(aeration)를 수행하지 않을 경우에 포기를 수행한 경우보다 Co 합금 박막 내 B과 W의 함량을 대폭증가시킬 수 있었고 최종적으로 Co-W-B 합금 박막의 경도를 8.9 (±0.3) GPa까지 향상시켰다.
Near-Infrared Reflective Dark-Tone Bilayer System for LiDAR-Based Autonomous Vehicles
임태호,배성희,유성호,백경열,조상호 한국고분자학회 2022 Macromolecular Research Vol.30 No.5
Light Detection and Ranging (LiDAR) is a representative sensor for autonomous v ehicles (AVs) by r ecognizing surrounding obj ects through d etecting the reflected near-infrared (NIR) light. However, this sensor has a weakness in recognizing the conventional carbon black-based dark-tone cars due to their low NIR reflectance. This cognitive impairment is a potential factor in a car accident in the AV system. Therefore, it is necessary to develop a dark-tone paint that can be applied to LiDAR by reflecting NIR. In this work, we developed a NIR reflective dark-tone bilayer system. As the bottom layer (surfacer layer), we used a conventional NIR-reflective surfacer. For the dark-tone top layer (basecoat layer), organic pigment-based paints were prepared. Various combinations of organic pigments such as perylene, copper(II) phthalocyanine, perylene diimide derivatives were studied to give a dark tone. After optimization, the developed bilayers exhibited dark tone with low L* values (less than 25) and high reflectance in the NIR region, over 60%, especially at 905 nm. Therefore, we expect the developed bilayer system to be applied as a dark-tone paint detectable by LiDAR.
공간다중화 방식을 사용하는 다중 안테나 시스템을 위한 감소된 계산량의 QRM-MLD 신호검출기법
임태호,김재권,조용수,Im, Tae-Ho,Kim, Jae-Kwon,Cho, Yong-Soo 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.1C
본 논문에서는 공간다중화 방식을 사용하는 MIMO(Multiple Input Multiple Output)시스템을 위한 수신부 신호 검출기법인 QRM-MLD (Maximum Likelihood Detection with QR Decomposition and M-algorithm)를 다룬다. 최근 산업현장에서는 차세대 이동통신에서 요구되는 보행자 속도로 움직이는 환경에서 1Gbps를 달성하기 위해 $4{\times}4$ MIMO 시스템에 QRM-MLD기법을 사용하여 1Gbps 전송속도의 testbed를 구현하였다. 본 논문에서는 QRM-MLB기법과 동일한 오류성능을 가지지만 계산량을 현격하게 줄이는 새로운 reduced complexity QRM-MLD기법을 제안한다. 두 가지 방식의 계산량을 엄밀하게 비교하여 계산량 감소정도를 정량적으로 표현하고 모의실험을 통해 제안된 방식이 기존의 방식과 동일한 오류성능을 보임을 확인한다. In the paper, we address QRM-MLD (Maximum Likelihood Detection with QR Decomposition and M-algorithm) signal detection method for spatially multiplexed MIMO (Multiple Input Multiple Output) systems. Recently, the QRM-MLD signal detection method which can achieve 1Gbps transmission speed for next generation mobile communication was implemented in a MIMO testbed for the mobile moving at a pedestrian speed. In the paper, we propose a novel signal detection method 'reduced complexity QRM-MLD' that achieves identical error performance as the QRM-MLD while reducing the computational complexity significantly. We rigorously compare the two detection methods in terms of computational complexity to show the complexity reduction of the proposed method. We also perform a set of computer simulations to demonstrate that two detection methods achieve identical error performance.