• Title/Summary/Keyword: noise robustness

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Shift and noise tolerance encryption system using a phase-based virtual image (가상위상영상을 이용한 잡음 및 변이에 강한 암호화 시스템)

  • 서동환;조규보;신창목;박상국;김성용;김수중
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.02a
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    • pp.62-63
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    • 2003
  • We propose an improved image encryption and the shift-tolerance method in the Fourier space using a virtual phase image. The encrypted image is obtained by the Fourier transform of the product of a phase-encoded virtual image, not an original image, and a random phase image. We demonstrate the robustness to noise, to data loss and shift of the encrypted image or the Fourier decryption key in the proposed technique.

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Vibration Control of a Rotating Cantilevered Beam Using Piezoceramic Actuators (압전 세라믹 작동기를 이용한 회전 외팔 보의 진동 제어)

  • 박종석;최승복;정재천
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.10a
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    • pp.255-259
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    • 1996
  • This paper presents active vibration control of a rotating cantilevered beam using piezoceramic actuators. A governing equation of motion is obtained by the Hamilton's principle and expressed in the state space representation. Subsequently, an H$_{\infty}$ control which is robust to system uncertainties is synthesized through the loop shaping design procedure. Computer simulations for the steady-state vibration control are undertaken in order to demonstrate the effectiveness and robustness of the proposed control methodology..y.

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Time delay control with state feedback for azimuth motion of the frictionless positioning device

  • Jeong, Ho-Seop;Lee, Chong-Won
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10a
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    • pp.385-388
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    • 1996
  • A time delay controller with state feedback is proposed for azimuth motion control of the frictionless positioning device which is subject to the variations of inertia in the presence of measurement noise. The time delay controller, which is combined with a low-pass filter to attenuate the effect of measurement noise, ensures the asymptotic stability of the closed loop system. It is found that the low-pass filter tends to increase the robustness in the design of time delay controller as well as the gain and phase margins of the closed loop system. Numerical and experimental results support that the proposed controller guarantees a good tracking performance irrespective of the variation of inertia and the presence of measurement noise.

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Robust Design of an ER Damper using Taguchi Method (다구찌법을 이용한 ER 댐퍼의 강건 설계)

  • 윤영민;배광식;김재환;최승복
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.157-162
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    • 2003
  • This Paper presents a robust design of an Electrorheological(ER) damper using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Electrode length, electrode gap, base oil viscosity and the weight ratio of ER particles are chosen for the control parameters and the temperature is considered to be a noise factor. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the electrode length and base oil viscosity of the ER fluid mostly affect the damping force in the absence of electric field. On the other hand, when the voltage is applied to the ER damper, the electrode length and the weight ratio of ER fluid exhibit significant effect. Based on the Taguchi method, an optimal configuration was designed and the robustness of the designed ER damper was validated by comparing the analysis and experimental results.

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A Robustness Performance Improvement of QE-MMA Adaptive Equalization Algorithm based on Dithering (Dithering을 이용한 QE-MMA 적응 등화 알고리즘의 Robustness 성능 개선)

  • Lim, Seung-Gag
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.3
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    • pp.93-98
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    • 2017
  • This paper relates with the robustness performance improvement of QE-MMA (Quantized Error-MMA) adaptive equalization algorithm based on the dithering in order to reduce the intersymbol interference by nonlinear distortion occurs at channel. The QE-MMA was appeared for the easiness of H/W implementation in place of multiplication to shifting in the tap coefficient updates applying the power-of-two operation to the magnitude of error signal in currently SE-MMA, it's performance were degraded by this. For improving it's performance, the proposed DQE-MMA adds the dither signal which has constant statistical characteristics in the prestage of power-of-two operation. It was confirmed by simulation that the DQE-MMA gives better robustness performance than current QE-MMA in the same channel and signal to noise ratio.

Robustness of Bayes forecast to Non-normality

  • Bansal, Ashok K.
    • Journal of the Korean Statistical Society
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    • v.7 no.1
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    • pp.11-16
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    • 1978
  • Bayesian procedures are in vogue to revise the parameter estimates of the forecasting model in the light of actual time series data. In this paper, we study the Bayes forecast for demand and the risk when (a) 'noise' and (b) mean demand rate in a constant process model have moderately non-normal probability distributions.

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CAE-based DFSS Study for Road Noise Reduction (Road Noise 개선을 위한 CAE 기반 DFSS Study)

  • Kwon, Woo-Sung;Yoo, Bong-Jun;Kim, Byoung-Hoon;Kim, In-Dong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.04a
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    • pp.735-741
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    • 2011
  • In the early phase of vehicle development, CAE is conducted as tool for vehicle performance assessment. To maintain acceptable road noise performance, solution for reduced vehicle sensitivity is required. Chassis interface dynamic stiffness characteristics are key component to isolating vibration and noise of road from the vehicle interior. This research provide how to set up the optimized dynamic characteristics under noise effect through DFSS study. CAE-based DOE is performed to build prediction math model, CMS process involves DOE to achieve very fast run times while giving results very comparable. Minimized $95^{th}$ percentile of performance distribution is applied to minimize vehicle sensitivity and road noise levels variation during the optimization process. Finally, the results of optimization were reviewed for performance and robustness.

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Echo Canceller with Improved Performance in Noisy Environments (잡음에 강인한 반향 제거기 연구)

  • 이세원;박호종
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.4
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    • pp.261-268
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    • 2003
  • Conventional acoustic echo cancellers using ES algorithm have simple structure and fast convergence speed compared with those using NLMS algorithm, but they are very weak to external noise because ES algorithm updates the adaptive filter taps based on average energy reduction rate of room impulse response in specific acoustical condition. To solve this problem, in this paper, a new update algorithm for acoustic echo canceller with stepsize matrix generator is proposed. A set of stepsizes is determined based on residual error energy which is estimated by two moving average operators, and applied to the echo canceller in matrix from, resulting in improved convergence speed. Simulations in various noise condition show that the proposed algorithm improves the robustness of acoustic echo canceller to external noise.

Robust Modal Parameter Idnentification Using Total Least Square Method (전최소자승법을 이용한 강인한 모드매개변수)

  • Jeong, Weui-Bong;Kim, Jun-Yeop;Kim, Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.3
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    • pp.843-849
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    • 1996
  • The least square estimation is used frequently in experimental modal analysis techinque to eliminate noise signals. However, identified modal parameters are sometimes inaccurate, since the least squre estimation is sensitive to noise. In this paper, a new total least squre estimation, which is robust to noise signals, is developed and applied to experimental modal analysis technique such as Prony method and Circle Fit method. Several simulated results show that the proposed method is robuster to noise than conventional method.

Constructing a Noise-Robust Speech Recognition System using Acoustic and Visual Information (청각 및 시가 정보를 이용한 강인한 음성 인식 시스템의 구현)

  • Lee, Jong-Seok;Park, Cheol-Hoon
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.8
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    • pp.719-725
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    • 2007
  • In this paper, we present an audio-visual speech recognition system for noise-robust human-computer interaction. Unlike usual speech recognition systems, our system utilizes the visual signal containing speakers' lip movements along with the acoustic signal to obtain robust speech recognition performance against environmental noise. The procedures of acoustic speech processing, visual speech processing, and audio-visual integration are described in detail. Experimental results demonstrate the constructed system significantly enhances the recognition performance in noisy circumstances compared to acoustic-only recognition by using the complementary nature of the two signals.