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Semi-Blind Channel Estimation for OFDM with Multiple Receive Antennas
Jin-Goog Kim,Kyun-Sang Park,Hyun-wook Jo,Jong-Tae Lim 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
This paper presents a semi-blind channel estimation scheme for OFDM systems with multiple receive antennas. Using the statistical property of the received signal, we combine the pilot-based least-squares estimator with the subspace-based blind estimator. To improve the performance of the subspace-based method, we reduce the effect on the residual error which affects the accuracy of the noise subspace. Simulation results show that the proposed method is effective and improves the performance.
Subspace-Based Iterative Semiblind Channel Estimation for MIMO-OFDM Considering Residual Error
Jin-Goog Kim,Jong-Tae Lim IEEE 2009 IEEE Transactions on Vehicular Technology VT Vol.58 No.8
<P>A new approach to subspace-based channel estimation for multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems is proposed. The proposed method exploits both the receive diversity and the statistical property of the received signal based on the iterative algorithm. To reduce the effect of residual error affecting the accuracy of the noise subspace, a measure called the Hermitian angle is introduced. In addition, the forgetting factor is used to consider a time-varying channel.</P>
MAP-Based Channel Estimation for MIMO–OFDM Over Fast Rayleigh Fading Channels
Jin-Goog Kim,Jong-Tae Lim IEEE 2008 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.57 No.3
<P>This paper presents a channel estimation scheme for multiple-input multiple-output with orthogonal frequency-division multiplexing (MIMO-OFDM) in fast varying Rayleigh channels. To handle rapid variation of channels within a transmission block, we propose a novel maximum a posteriori probability-based channel estimation scheme using pilot symbols. With the estimate of the channel matrix for the current symbol interval, a zero-forcing (ZF) receiver is applied to detect the spatially multiplexed data. In simulation results, the effectiveness of the proposed method is shown, as compared with the polynomial and the perfect channel estimates.</P>
Subspace-based Semi-blind Channel Estimation for SIMO-OFDM Systems by using Antenna Diversity
Jin-Goog Kim,Jong-Tae Lim 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
A new approach to semi-blind channel estimation for single-input multiple-output orthogonal frequency division multiplexing (SIMO-OFDM) systems is proposed. The proposed method exploits both the antenna diversity and the statistical property of the received signal. By exploiting the receive antenna diversity, the residual error is reduced. In addition, we provide a method resolving ambiguity by using pilot symbols. Simulation results show that the proposed method results in better performance compared with the existing methods.
SNR에 기초한 순환적 전치 부호를 가지는 시스템에서 고유필터를 사용한 잡음 제거
김진국(Jin-Goog Kim) 한국통신학회 2014 韓國通信學會論文誌 Vol.39 No.10(네트워크)
본 논문에서는 순환적 전치 부호를 가지는 시스템에서 수신기에 나타나는 잡음신호를 제거하는 기법에 대해 다룬다. 수신된 블록의 SNR을 추정하여 잡음신호가 작을 때 수신된 블록으로부터 자기상관행렬을 구하고, 신호 부분공간(signal subspace)에 속하는 고유벡터를 자기상관행렬의 고유치 분해를 통해 얻는다. 신호 고유벡터를 위한 자기상관행렬은 수신된 블록의 순환적 특성을 사용하여 얻는다. 일반적인 OFDM 시스템에서는 순환적 전치 부호를 가지는 심볼을 전송하기 때문에 본 논문에서 제안한 방법은 송·수신기의 구조를 변경하지 않는 장점을 가진다. 고유필터를 위해 얻어진 신호 고유벡터를 사용하여 수신된 블록을 필터링함으로써 잡음신호를 제거한다. 제안된 방법의 타당성 검증을 위해 송신 신호에 대한 영구 여기(persistency of excitation) 조건을 확인하고 시뮬레이션을 통해 검증한다. In this paper, we propose the noise reduction method by using the eigenfilter in cyclic prefix system based on SNR. To obtain the signal eigenvectors for the eigenfiltering, we propose a method of obtaining the autocorrelation matrix by exploiting the circulant property of the received block which results from the cyclic extension of the OFDM symbol. Since the structures of the transmitter and the receiver are not changed, the proposed method is easy to apply to the conventional OFDM system. To verify the proposed method, we evaluate the persistency of excitation (POE) criterion for the input and demonstrate the effectiveness of the proposed method in the simulation results.
이윤국(Youn-Goog Lee),김난희(Nan-Hee Kim),최영섭(Young-Seop Choi),김선정(Sun-Jung Kim),박주현(Ju-Hyun Park),강유미(Yu-Mi Kang),배석진(Seok-Jin Bae),서계원(Kye-Won Seo),김종민(Jong-Min Kim) 한국환경보건학회 2020 한국환경보건학회지 Vol.46 No.2
Objective: This study is designed to measure the concentration of DBPs (disinfection by-products) in pool water and in air and to estimate the carcinogenic potential through the evaluation of inhalation exposure. Methods: The subjects were six indoor swimming pools with many users in Gwangju. Samples of pool water and indoor air were taken every one month from August 2018 to August 2019 and analyzed for eight swimming pool standards. Three-liter air samples were collected and the VOCs were analyzed using GC/MS directly connected to thermal desorption. Results: pH was 6.8-7.5 and the concentration of free residual chlorine in pool water was 0.40-0.96 ?/ℓ. Physicochemical test items such as KMnO₄ consumption and heavy metal items such as Aluminum met existing pool hygiene standards. No VOC materials were detected except for the DBPs. The concentration of THMs in the pool water was 11.05-41.77 µg/L and the THMs mainly consist of Chloroform (63-97%) and BDCM (3- 31%). The concentration of indoor air THMs is 13.24-32.48 µg/m3 and consists of Chloroform. The results of carcinogenic assessment of chloroform in the indoor swimming pool via inhalation exposure were 2.0 to 6.4 times higher than the ‘acceptable risk level’ suggested by the US EPA. Conclusions: The concentration of THMs in the pool water is 11.05-41.77 µg/L, most of which is chloroform. In addition, the concentration of indoor air THMs is 13.24-32.48 µg/㎥ . The result of carcinogenic assessment of chloroform was 2.0 to 6.4 times higher than the ‘acceptable risk level’ suggested by the US EPA.
이윤국 ( Youn Goog Lee ),박옥현 ( Ok Hyun Park ),안상수 ( Sang Su An ),김연희 ( Yun Hee Kim ),김종민 ( Jong Min Kim ),배석진 ( Seak Jin Bae ),백계진 ( Kye Jin Paik ),문용운 ( Young Woon Moon ) 한국환경분석학회 2011 환경분석과 독성보건 Vol.14 No.3
This study was performed to investigate the quality of spring water during the rainy periods in Mudeung mountain, in April, May, July and August 2010. The variation of physicochemical items such as pH, TDS, NO3-N, Cl-, SO4(2-) was not signigicant and the concentration at each sites satisfied with drinking water guideline except that of turbidity. The content variation of minerals like Ca2+, Mg2+, K+, Na+ showed generally stable during the rainy periods. Even though a photo catalyte sterilizer was used, total coliforms and fecal coliforms were detected in every sample collected, except for the one from Neutjae. That is why the sterilizing facility is exposed to many environmental variables such as insolation and rainfall. According to the distribution of species, at Jungmeorijae, total coliforms proliferate because of fecal contamination. However, at Neutjae, total coliforms were caused by plant, soil and water, rather than fecal.
굴삭기 주행모터 기어 케리어의 위상 최적설계에 관한 연구
김동은(Dong-Eun Kim),김찬희(Chan-Hea Kim),김홍태(Hong-Tae Kim),허도은(Do-Eun Hea),한국남(Goog-Nam Han),이석순(Seok-Soon Lee),황영진(Young-Jin Hwang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The excavator travel on off-road and on-road. So traveling motor's gear carrier must be more stiffness and lightweight. In this study we performed FEA(Finite Element Analysis) for the traveling motor's gear carrier and performed topology optimization base on the results of FEA. We performed topology optimization with the control of the shape size which is the results of topology optimization and suggested the shaped of the excavator traveling motor's gear carrier of topology optimization.