• Title, Summary, Keyword: CSI

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Linear Precoding Based on the Imperfect CSI Without Knowing the CSI Reliability (신뢰도를 모르는 불완전한 채널 정보에 기초한 선형 프리코딩)

  • Lee, Woong;Yoon, Eunchul
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.9
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    • pp.1678-1685
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    • 2015
  • We propose a linear precoding scheme combining the merits of beamforming and orthogonal space-time block coding based on the imperfect CSI without knowing the CSI reliability. We first investigate the impact of the CSI reliability on precoding performance by assuming various values of the CSI reliability. Then, we propose a method of predicting the CSI reliability based on the received SNR for the design of an efficient precoder. We show the efficiency of the proposed scheme by simulation.

Feasibility of Proton Chemical Shift Imaging with a Stereotactic Headframe

  • 백현만;최보영;손병철;정성택;이형구;서태석
    • Proceedings of the Korean Society of Medical Physics Conference
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    • pp.72-72
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    • 2003
  • Purpose: To prove feasibility of proton chemical shift imaging (lH CSI) during stereotactic procedure, authors performed IH CSI in combination with a stereotactic headframe and selected targets according to local metabolic information, evaluated the pathologic results. Methods: The 1H CSI directed stereotactic biopsy was performed in five patients. 1H CSI was performed before conventional stereotactic MRI with gadolinium enhancement for stereotactic coordinates. The metabolite images expressed as integral ratios, Cho/Cr and Lac/Cr, were displayed in different colors. The stereotactic target coordinates were correlated with the coordinates from the 1H CSI images. Results: The final pathologic results obtained were concordant with the local metabolic information from 1H CSI. We believe that 1H CSI-directed stereotatic biopsy has the potential to significantly improve the accuracy of stereotactic biopsy targeting. Conclusions : Metabolic signals derived from 1H CSI could give us more direct clues for stereotactic target selection during the subsequent conventional stereotactic MR imaging. 1H CSI was feasible with the stereotatic headframe in place. The final pathologic results obtained were concordant with the local metabolic information from 1H CSI. Acknowledgement: This study was supported by a grant of the Center for Functional and Metabolic Imaging Technology, Ministry of Health & Welfare, Republic of Korea (02-PJ3-PG6-EV07-0002).

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Comparison between cerebral state index and bispectral index during desflurane anesthesia

  • Cho, Sang-Hyeon;Kim, Sung-Su;Hyun, Dong-Min;Yoon, Hyeong-Suk;Han, Jung-Woo;Kim, Jin Sun
    • Korean Journal of Anesthesiology
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    • v.71 no.6
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    • pp.447-452
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    • 2018
  • Background: Cerebral state index (CSI) is an anesthesia depth monitor alternative to bispectral index (BIS). Published comparative studies have used propofol or sevoflurane. However, studies using desflurane have not been reported yet. Different volatile anesthetics have different electroencephalography signatures. The performance of CSI may be different in desflurane anesthesia. Therefore, the objective of this study was to compare CSI and BIS during desflurane anesthesia. Methods: Thirty-three patients were recruited. Desflurane and remifentanil were used to maintain general anesthesia. BIS and CSI were recorded simultaneously every minute. End-tidal concentration of desflurane was maintained at 4% from the beginning of surgery for 5 minutes. Pairwise data of CSI and BIS were obtained five times at one-minute intervals. This process was repeated in the order of 6%, 8%, and 10%. Results: BIS and CSI were negatively correlated with the end-tidal concentration of desflurane with a similar degree of correlation (correlation coefficient BIS: -0.847, CSI: -0.844). The relationship between CSI and BIS had a good linearity with a slope close to 1 ($R^2=0.905$, slope = 1.01). For the relationship between CSI and BIS at each end-tidal concentration of desflurane, CSI and BIS showed good linearity in 4% and 10% ($R^2=0.559$, 0.540). However, the linearity and slope were decreased in 6% and 8% ($R^2=0.163$, 0.014). Conclusions: CSI showed an equivalent degree of overall performance compared to BIS in desflurane anesthesia. Accounting for previous literature, CSI can be used as a good substitute for BIS regardless of the kind of anesthetics used.

MIPI CSI-2 & D-PHY Camera Controller Design for Future Mobile Platform (차세대 모바일 단말 플랫폼을 위한 MIPI CSI-2 & D-PHY 카메라 컨트롤러 구현)

  • Hyun, Eu-Gin;Kwon, Soon;Jung, Woo-Young
    • The KIPS Transactions:PartA
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    • v.14A no.7
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    • pp.391-398
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    • 2007
  • In this paper, we design a future mobile camera standard interface based on the MIPI CSI-2 and D-PHY specification. The proposed CSI-2 have the efficient multi-lane management layer, which the independent buffer on the each lane are merged into single buffer. This scheme can flexibly manage data on multi lanes though the number of supported lanes are mismatched in a camera processor transmitter and a host processor. The proposed CSI-2 & D-PHY are verified under test bench. We make an experiment on CSI-2 & D-PHY with FPGA type test-bed and implement them onto a mobile handset. The proposed CSI-2 & D-PHY module are used as both the bridge type and the future camera processor IP for SoC.

Input Current/Torque Ripple Compensation of Current Source Induction Motor Drives using Active Power Filters (능동전력필터에 의한 전류형 인버터 구동 유도모터의 입력전류 및 토크맥동 보상)

  • 정영국;조재연;임영철
    • The Transactions of the Korean Institute of Power Electronics
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    • v.6 no.2
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    • pp.158-163
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    • 2001
  • Current Source Inverter(CSI), operated in square wave mode, is more efficient thant the PWM CSI because of increased cost, greater complexity of control algorithm and substantial switching losses, EMI. But, the square wave output current of CSI, rich in low order harmonics produce motor torque ripples. Therefore, in this paper, describes active power filters for compensating square wave input current of current source induction motor. Also, notch filtering as compensation algorithm is employed. To confirm the validity of proposed system, PSIM simulation results are presented and discussed.

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Interference Tolerant Based CR System with Imperfect Channel State Information at the CR-Transmitter

  • Asaduzzaman, Asaduzzaman;Kong, Hyung-Yun
    • Journal of electromagnetic engineering and science
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    • v.11 no.2
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    • pp.128-132
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    • 2011
  • In interference tolerance based spectrum sharing systems, primary receivers (PRs) are protected by a predefined peak or average interference power constraint. To implement such systems, cognitive radio (CR) transmitters are required to adjust their transmit power so that the interference power received at the PR receivers is kept below the threshold value. Hence, a CR-transmitter requires knowledge of its channel and the primary receiver in order to allocate the transmit power. In practice, it is impossible or very difficult for a CR transmitter to have perfect knowledge of this channel state information (CSI). In this paper, we investigate the impact of imperfect knowledge of this CSI on the performances of both a primary and cognitive radio network. For fixed transmit power, average interference power (AIP) constraint can be maintained through knowledge of the channel distribution information. To maintain the peak interference power (PIP) constraint, on the other hand, the CR-transmitter requires the instantaneous CSI of its channel with the primary receiver. First, we show that, compared to the PIP constraint with perfect CSI, the AIP constraint is advantageous for primary users but not for CR users. Then, we consider a PIP constraint with imperfect CSI at the CR-transmitter. We show that inaccuracy in CSI reduces the interference at the PR-receivers that is caused by the CR-transmitter. Consequently the proposed schemes improve the capacity of the primary links. Contrarily, the capacities of the CR links significantly degrade due to the inaccuracy in CSI.

A Channel State Information Feedback Method for Massive MIMO-OFDM

  • Kudo, Riichi;Armour, Simon M.D.;McGeehan, Joe P.;Mizoguchi, Masato
    • Journal of Communications and Networks
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    • v.15 no.4
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    • pp.352-361
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    • 2013
  • Combining multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) with a massive number of transmit antennas (massive MIMO-OFDM) is an attractive way of increasing the spectrum efficiency or reducing the transmission energy per bit. The effectiveness of Massive MIMO-OFDM is strongly affected by the channel state information (CSI) estimation method used. The overheads of training frame transmission and CSI feedback decrease multiple access channel (MAC) efficiency and increase the CSI estimation cost at a user station (STA). This paper proposes a CSI estimation scheme that reduces the training frame length by using a novel pilot design and a novel unitary matrix feedback method. The proposed pilot design and unitary matrix feedback enable the access point (AP) to estimate the CSI of the signal space of all transmit antennas using a small number of training frames. Simulations in an IEEE 802.11n channel verify the attractive transmission performance of the proposed methods.

Impact of Outdated CSI on the Performance of Incremental Amplify-and-Forward Opportunistic Relaying

  • Zhou, Tsingsong;Gao, Qiang;Fei, Li
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.6
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    • pp.2567-2582
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    • 2016
  • This paper investigates the impact of outdated channel state information (CSI) on the performance of the incremental amplify-and-forward (AF) opportunistic relaying (OR) over dual-hop Rayleigh fading channels. According to the definition of distribution function, we obtain the cumulative distribution function (CDF) of the actual combined signal-to-noise ratio (SNR) received at the destination. Based on this CDF, the closed-form expressions of the average spectral efficiency and outage probability are derived for the incremental AF OR under outdated CSI. Numerical results show that in the low region of the average SNR of the direct link, outdated CSI deteriorates the system performance, whereas in the high region, outdated CSI has almost no impact on the system performance.

Performance Improvement on Adaptive OFDM System with a Multi-Step Channel Predictor over Mobile Fading Channels (이동 페이딩 채널하의 멀티 스텝 채널 예측기를 이용한 적응 OFDM 시스템의 성능개선)

  • Ahn, Hyun-Jun;Kim, Hyun-Dong;Choe, Sang-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.12A
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    • pp.1182-1188
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    • 2006
  • Adaptive OFDM(Orthogonal Frequency Division Multiplexing) improves data capacity and system performance over multipath fading by adaptively changing modulation schemes according to channel state information(CSI). To achieve a good performance in adaptive OFDM systems, CSI should be transmitted from receiver to transmitter in real time through feedback channel. However, practically, the CSI feedback delay d which is the sum of the data processing delay and the propagation delay is not negligible and damages to the reliability of CSI such that the performance of adaptive OFDM is degraded. This paper presents an adaptive OFDM system with a multistep predictor on the frequency axis to effectively compensate the multiple feedback delays $d(\geq2)$. Via computer simulation we compare the proposed scheme and existing adaptive OFDM schemes with respect to data capacity and system performance.

Reliability and Validity of the Korean Version of the Client Satisfaction Inventory (한국어판 사회복지서비스 이용자 만족도 척도(Client Satisfaction Inventory)의 신뢰도와 타당도 평가: 종합사회복지관을 중심으로)

  • Kim, Yong-Seok;Lee, Eun-Young;Ko, Kyung-Eun;Min, Eun-Hee
    • Korean Journal of Social Welfare
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    • v.59 no.4
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    • pp.83-109
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    • 2007
  • Client satisfaction has been getting more attention in the field of social work in Korea. However, there have been very few standardized tools to measure the construct. The purpose of this study is to develop the Korean version of the Client Satisfaction Inventory developed by McMurtry and Hudson. This study was conducted with a total of 259 clients of 6 social service agencies in Seoul metropolitan areas. Based upon the results of factor analysis, the Korean version of the Client Satisfaction Inventory(CSI-K) is considered a two-factor measure. The alpha coefficients of the subscales of the CSI-K are .964 and .885 which are considered very high. The subscales are significantly correlated with convergent variables and very weakly correlated with discriminant variables. It is suggested that scales more suitable for social work settings in Korean be developed.

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