• Title, Summary, Keyword: Information Suppression

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Control Strategy and Characteristic Analysis of Hybrid Active Power Filters with the Resonant Impedance Principle

  • Fang, Lu;Xu, Xian-Yong;Luo, An;Li, Yan;Tu, Chun-Ming;Fang, Hou-Hui
    • Journal of Power Electronics
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    • v.12 no.6
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    • pp.935-946
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    • 2012
  • A new kind of resonant impedance type hybrid active filter (RITHAF) is proposed for dynamic harmonic current suppression and high capacity reactive compensation in medium and high voltage systems. This paper analyzed the different performance of the RITHAF when the active part of the RITHAF is controlled as a current source and as a voltage source, respectively. The harmonic suppression function is defined in this paper. The influences of the changes caused by the grid impedance and the detuning of the passive power filter on the compensating characteristics of the RITHAF are studied by analyzing the suppression function. Simulation and industrial application results show that the RITHAF has excellent performances in harmonic suppression and reactive compensation, which is suitable for medium and high voltage systems.

Information Suppression and Projection Strategies Depending on Personality Traits: Using Social media for Impression Management (사용자의 성격에 따른 정보의 통제와 투사 전략: 인상관리를 위한 소셜미디어의 활용)

  • Yun, Haejung;Lee, Hanbyeol;Lee, Choong C.
    • Knowledge Management Research
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    • v.18 no.3
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    • pp.147-162
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    • 2017
  • As social media started to work as important communication tools, social media users have tried to manage their image, identity, and impression through social media. Social media service providers have been interested in providing various functions effectively disclosing users' emotion, such as posting, commenting, and sharing content; on the other hand, relatively few efforts have been made to provide social media functions for information suppression. In this study, therefore, we attempt to examine the relationship between Facebook users' personality and impression management behaviors. Personal traits of users including public self-consciousness, positive self-expression, and honest self-expression were considered as independent variables. Impression management behaviors are composed of two variables, which are suppression and projection. The survey was conducted, targeting 230 Facebook users. The research findings show that public self-consciousness and positive self-expression are positively associated with information suppression while both positive and honest self-expression is positively associated with information projection.

Adaptive Lattice Step-Size Algorithm for Narrowband Interference Suppression in DS/CDMA Systems

  • Benjangkaprasert, Chawalit;Teerasakworakun, Sirirat;Jorphochaudom, Sarinporn;Janchitrapongvej, Kanok
    • 제어로봇시스템학회:학술대회논문집
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    • pp.2087-2089
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    • 2003
  • The presence of narrowband interference (NBI) in Direct-sequence code division multiple access (DS/CDMA) systems is an inevitable problem when the interference is strong enough. The improvement in the system performance employs by adaptive narrowband interference suppression techniques. Basically there have been two types of method for narrowband interference suppression estimator/subtracter approaches and transform domain approaches. In this paper the focus is on the type of estimator/subtracter approaches. However, the binary direct sequence (DS) signal, that acts as noise in the prediction process is highly non-Gaussian. The case of a Gaussian interferer with known in an autoregressive (AR) signal or a digital signal and also in a sinusoidal signal (Tone) that included in is paper. The proposed NBI suppression is presence in an adaptive IIR notch filter for lattice structure and more powerful by using a variable step-size algorithm. The simulation results show that the proposed algorithm can significantly increase the convergence rate and improved system performance when compare with adaptive least mean square algorithm (LMS).

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TDMA jammer suppression on CDMA overlay

  • 김동구;박형일
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.4
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    • pp.961-971
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    • 1996
  • The effect of inband TDMA narrow band jammers to DS-CDMA system performance and the suppression techniques are investigated using Monte Carlo simulations. TIA stantard North American Digital Cellular wea used as jammer. Levinson Dubin and conventional recursive least square algorithm were emphasized since these techniques can be implemented with a few DSPs for CDMA application. Two filter structures, i.e., complex suppression filter and real suppression filter in each inphase and quadrature channels, are investigated and their performances are compared. Complex suppression filter with Levinson Durbin algorithm of 20msec updata rate is the most promising with respect to implementation and performance poit of view. Implementation feasibility is discussed and the channel capacity lost by suppression is computed.

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Residual Echo Suppression Based on Tracking Echo-Presence Uncertainty (Tracking Echo-Presence Uncertainty 기반의 잔여 반향 억제)

  • Park, Yun-Sik;Chang, Joon-Hyuk
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.10C
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    • pp.955-960
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    • 2009
  • In this paper, we propose a novel approach to residual echo suppression (RES) algorithm based on tracking echo-presence uncertainty (TEPU) to improve the performance of acoustic echo suppression (AES) in the frequency domain. In the proposed method, the ratio of the microphone input and the echo-suppressed output signal power is employed as the threshold value for the decision rule to estimate the echo-presence uncertainty applied to the RES filter. The proposed RES scheme estimates the echo presence uncertainty in each frequency bin and effectively reduces residual echo signal in a simple fashion. The performance of the proposed algorithm is evaluated by the objective test and yields better results compared with the conventional schemes.

Modified Wilkinson Power Divider for nth Harmonic Suppression (고조파 제거 기능을 갖는 윌킨슨 전력분배기의 설계)

  • Kim, Jong-Sung
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.1
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    • pp.46-50
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    • 2013
  • A modified design that can reject the nth harmonic components in the Wilkinson power divider is presented. After adding transmission lines of electrical lengths determined by suppression terms between two transformers of the traditional design, a solution of the modified Wilkinson divider can be found. Experimental results show the second and third harmonic suppression to be -45.3 dB and -46.4 dB, respectively, while maintaining the conventional performance at the fundamental frequency.

Analysis of the JND-Suppression Effect in Quantization Perspective for HEVC-based Perceptual Video Coding

  • Kim, Jaeil;Kim, Munchurl
    • IEIE Transactions on Smart Processing and Computing
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    • v.4 no.1
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    • pp.22-27
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    • 2015
  • Transform-domain JND (Just Noticeable Difference)-based for PVC (Perceptual Video Coding) is often performed in quantization processes to effectively remove perceptual redundancy. This study examined the JND-suppression effects on quantized coefficients of transform in HEVC (High Efficiency Video Coding). To reveal the JND-suppression effect in quantization, the properties of the floor functions were used for modeling the quantized coefficients, and a JND-adjustment process in an HEVC-compliant PVC scheme was used to tune the JND values by analyzing the JND suppression effect. In the experimental results, the bitrate reduction decreases slightly, but the PSNR and perceptual quality are improved significantly when the proposed JND adjustment process is applied.

PN Code Acquisition in a DS/CDMA Overlay Environment

  • Kim, Jin-Young
    • Proceedings of the IEEK Conference
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    • pp.185-188
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    • 2000
  • In this paper, performance of a PN code acquisition scheme is analyzed and simulated for a DS/CDMA overlay system where a CDMA user and a narrowband user coexist in the same frequency band. To suppress the NBI, an interference suppression filter is employed at the receiver front-end. From the simulation results, it is shown that the interference suppression filter is very effective for suppression of the NBI and rapid PN code acquisition in a DS/CDMA overlay environment. It is also shown that the one-sided tap number of 5 fur interference suppression filter is sufficient to suppress the NBI.

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Blooming Suppression of an npn MOS Image Sensor (npn MOS 영상소자의 블루밍억제에 관한 연구)

  • 갑형철;민홍식;이종덕
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.4
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    • pp.417-421
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    • 1988
  • In order to analyze the blooming suppression mechanism of a MOS image sensor, test photodiodes have been fabricated and characterized by attaching a source follower circuit. The blooming suppression ability of npn structure compared to that of np structure is quantitatively analyzed and measured by experiment. The dependency of the blooming current on the substrate voltage, the vertical MOS gate voltage and the video voltage is measured and the optimum condition for blooming suppression is presented.

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Matrix Decomposition for Low Computational Complexity in Orthogonal Precoding of N-continuous Schemes for Sidelobe Suppression of OFDM Signals

  • Kawasaki, Hikaru;Matsui, Takahiro;Ohta, Masaya;Yamashita, Katsumi
    • IEIE Transactions on Smart Processing and Computing
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    • v.6 no.2
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    • pp.117-123
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    • 2017
  • N-continuous orthogonal frequency division multiplexing (OFDM) is a precoding method for sidelobe suppression of OFDM signals and seamlessly connects OFDM symbols up to the high-order derivative for sidelobe suppression, which is suitable for suppressing out-of-band radiation. However, it severely degrades the error rate as it increases the continuous derivative order. Two schemes for orthogonal precoding of N-continuous OFDM have been proposed to achieve an ideal error rate while maintaining sidelobe suppression performance; however, the large size of the precoder matrices in both schemes causes very high computational complexity for precoding and decoding. This paper proposes matrix decomposition of precoder matrices with a large size in the orthogonal precoding schemes in order to reduce computational complexity. Numerical experiments show that the proposed method can drastically reduce computational complexity without any performance degradation.