• Title/Summary/Keyword: Recursive Convolution

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Computational Speed Comparison between FFT Convolution and Recursive Filtering

  • Lee, Hyeong-Ho
    • Proceedings of the KIEE Conference
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    • 1979.08a
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    • pp.166-167
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    • 1979
  • Performances of three computational algorithms for one-dimensional frequency filtering are compared and tradeoffs are studied. If the size of the filter impulse response is small, it is well-known that the conventional convolution is superior than the FFT convolution. If the size of the impulse response is large, it was suggested that the recursive filter might be competitive in terms of speed to the FFT convolution. We, therefore, have developed an computational, algorithm for the recursive filter to compare the speed advantages over the FFT convolution and the results are presented.

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A Note on Oceanographic Applications of Digital Filters (디지탈필터의 海洋學的 應용)

  • Kim, Hee Joon;Kang, Yong Q
    • 한국해양학회지
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    • v.19 no.2
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    • pp.133-140
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    • 1984
  • Oceanographic applications of digital filters are studied with special emphasis on the convolution filter with Hamming window and the recursive filters. Convolution filters are simple to understand and easy to design but not efficient for a long data set. Recursive filters, despite of the complexities, have advantages on economy and filter characteristic. By means of digital filtering technique we find that the alongshore wind at Pusan and the sea surface temperature at Gampo in summers during 1973 to 1979 are negatively correlated at low frequencies (periods longer than 5 days) but not so at high frequencies.

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A Dispersive APML using Piecewise Linear Recursive Convolution for FDTD Method (FDTD법을 이용하여 분산매질을 고려하기 위한 PLRC-APML 기법)

  • Lee Jung-Yub;Lee Jeong-Hae;Kang No-Weon;Jung Hyun-Kyo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.10 s.89
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    • pp.977-982
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    • 2004
  • In this paper, a dispersive anisotropic perfectly matched layer(APML) is proposed using piecewise linear recursive convolution(PLRC) for finite difference time domain(FDTD) methods. This proposed APML can be utilized for the analysis of a nonlinear dispersive medium as absorbing boundary condition(ABC). The formulation is simple modification to the original AMPL and can be easily implemented. Also it has some advantages of the PLRC approach-fast speed, low memory cost, and easy formulation of multiple pole susceptibility. We applied this APML to 2-D propagation problems in dispersive media such as Debye and Lorentz media The results showed good absorption at boundaries.

Memory-Efficiently Modified JEC (FD)2TD Method for Debye Medium (Debye 매질에 대한 메모리 효율적인 JEC (FD)2TD 수치 해석 기법)

  • Kim Hyun;Hong Ik-Pyo;Yook Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.5 s.96
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    • pp.447-454
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    • 2005
  • JEC method for Debye medium is required more memory resources and long calculation time than already well-known method such as RC method. It has been observed that JEC method would be converted to a memory effcient method by a change of discrete convolution integral range. The modified JEC method proposed here requires memory and calculation time similar to RC method, while it has a same or a smaller dispersion error than conventional methods, RC and JEC.

A FLUID TRANSIENT ANALYSIS FOR THE PROPELLANT FLOW WITH AN UNSTEADY FRICTION IN A MONOPROPELLANT PROPULSION SYSTEM (단일추진제 추진시스템의 비정상 마찰을 고려한 과도기유체 해석)

  • Chae Jong-Won
    • Journal of computational fluids engineering
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    • v.11 no.1 s.32
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    • pp.43-51
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    • 2006
  • A fluid transient analysis on the Koreasat 1 & 2 pipeline system is conducted through numerical parametric studies in which unsteady friction results are compared with quasi-steady friction results and show relatively accurate prediction of the response curve with the unsteady friction. The code developed and used in this analysis has finished verification through comparing with the original Zielke model, the full and recursive convolution model and quasi-steady model as a reference. The unsteady friction is calculated by the recursive convolution Zielke model in which a complete evolution history of velocity field is no longer required so that it makes the fluid transient analysis on the complicated system possible. The results show that the application of quasi-steady friction to model cannot predict the entire response curve properly except the first peak amplitude but the application of unsteady friction to model can predict reasonably the response curve, therefore it is to know the characteristics of the propulsion system.

A fluid transient analysis for the propellant flow with an unsteady friction in a monopropellant propulsion system

  • Chae Jong-Won;Han Cho-Young
    • 한국전산유체공학회:학술대회논문집
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    • 2006.05a
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    • pp.320-323
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    • 2006
  • A fluid transient analysis on the Koreasat 1 & 2 pipeline system is conducted through numerical parametric studies in which unsteady friction results are compared with quasi-steady friction results and show relatively accurate prediction of the response curve with the unsteady friction. The code developed and used in this analysis has finished verification through comparing with the original Zielke model, the full and recursive convolution model and quasi-steady model as a reference. The unsteady friction is calculated by the recursive convolution Zielke model in which a complete evolution history of velocity field is no longer required so that it makes the fluid transient analysis on the complicated system possible. The results show that the application of quasi-steady friction to model cannot predict the entire response curve properly except the first peak amplitude but application of unsteady friction to model can predict reasonably he response curve, therefore it is to know the characteristics of the propulsion system.

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Design of a Recursive Structure-based FIR Digital Filter (재귀 구조에 기반한 FIR 디지털 필터의 설계)

  • Jae-Jin Lee;David Tien;Gi-Yong Song
    • Journal of the Institute of Convergence Signal Processing
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    • v.5 no.2
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    • pp.159-164
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    • 2004
  • This paper proposes a new digital filter implementation which adopts an identical structure at both behavioral and logic level in top-down design. This methodology is based on the observation that multiplication is a form of convolution and carrying, and therefore multiplication is implemented with the same structure as that of a convolution in a recursive manner at the logic level. In order to demonstrate a recursive structure-based FIR digital filter, we select L-tap transposed and systolic FIR filters, and implement them to have a single structure. The proposed filter design becomes regular and modular because of the recursive adoption of a single structure for convolutions, and is very compact in that it needs only two 1-bit I/O ports in addition to significant improvement on hardware complexity without time penalty on the output sequence.

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Fast Bilateral Filtering Using Recursive Gaussian Filter for Tone Mapping Algorithm

  • Dewi, Primastuti;Nam, Jin-Woo;Cha, Eui-Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2010.05a
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    • pp.176-179
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    • 2010
  • In this paper, we propose a fast implementation of Bilateral filter for tone mapping algorithm. Bilateral filter is able to preserve detail while at the same time prevent halo-ing artifacts because of improper scale selection by ensuring image smoothed that not only depend on pixel closeness, but also similarity. We accelerate Bilateral filter by using a piecewise linear approximation and recursive Gaussian filter as its domain filter. Recursive Gaussian filter is scale independent filter that combines low cost 1D filter which makes this filter much faster than conventional convolution filter and filtering in frequency domain. The experiment results show that proposed method is simpler and faster than previous method without mortgaging the quality.

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Single Image Super-resolution using Recursive Residual Architecture Via Dense Skip Connections (고밀도 스킵 연결을 통한 재귀 잔차 구조를 이용한 단일 이미지 초해상도 기법)

  • Chen, Jian;Jeong, Jechang
    • Journal of Broadcast Engineering
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    • v.24 no.4
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    • pp.633-642
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    • 2019
  • Recently, the convolution neural network (CNN) model at a single image super-resolution (SISR) have been very successful. The residual learning method can improve training stability and network performance in CNN. In this paper, we propose a SISR using recursive residual network architecture by introducing dense skip connections for learning nonlinear mapping from low-resolution input image to high-resolution target image. The proposed SISR method adopts a method of the recursive residual learning to mitigate the difficulty of the deep network training and remove unnecessary modules for easier to optimize in CNN layers because of the concise and compact recursive network via dense skip connection method. The proposed method not only alleviates the vanishing-gradient problem of a very deep network, but also get the outstanding performance with low complexity of neural network, which allows the neural network to perform training, thereby exhibiting improved performance of SISR method.

Frequency-Domain RLS Algorithm Based on the Block Processing Technique (블록 프로세싱 기법을 이용한 주파수 영역에서의 회귀 최소 자승 알고리듬)

  • 박부견;김동규;박원석
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.240-240
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    • 2000
  • This paper presents two algorithms based on the concept of the frequency domain adaptive filter(FDAF). First the frequency domain recursive least squares(FRLS) algorithm with the overlap-save filtering technique is introduced. This minimizes the sum of exponentially weighted square errors in the frequency domain. To eliminate discrepancies between the linear convolution and the circular convolution, the overlap-save method is utilized. Second, the sliding method of data blocks is studied Co overcome processing delays and complexity roads of the FRLS algorithm. The size of the extended data block is twice as long as the filter tap length. It is possible to slide the data block variously by the adjustable hopping index. By selecting the hopping index appropriately, we can take a trade-off between the convergence rate and the computational complexity. When the input signal is highly correlated and the length of the target FIR filter is huge, the FRLS algorithm based on the block processing technique has good performances in the convergence rate and the computational complexity.

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