• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.1
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• pp.1-9
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• 1989

The convergence analysis of adavtive control schemes has been studied over the past decades, but the importance of structure to fast conversgece of adaptive control systems is still a controversial issue. This paper deals with the relative improvement of the exponential rate of convergence in adaptive error models. The Lyapunov's direct method is applied to adaptive control systems in order to improve the convergence rate by modifying the feedback structure of the error systems. Some simulation examples are illustrated to show fast convergence and robustness of these schemes.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.1-2
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• 2015

본 논문에서는 ANC 시스템의 빠른 수렴을 위하여 2차 경로 필터를 초기화하는 방법을 제안한다. 대부분의 ANC 시스템에서는 2차 경로 필터를 설계하기 위하여 LMS 알고리즘을 사용한다. 그러나 기존의 방법들은 2차 경로 필터의 초기 계수 값을 0으로 설정하기 때문에 필터의 수렴 시간이 길어진다. 이를 해결하기 위하여 본 논문에서는 미리 구한 계수 값을 2차 경로 필터의 초기값으로 설정하여 필터의 수렴 시간을 줄이는 방법을 제안한다. 제안한 방법을 사용하면 2차 경로 필터의 초기 단계부터 에러가 작게 나타내며, 이에 따라 ANC 시스템의 수렴이 빨라진다. 상용 헤드셋을 이용하여 제안하는 방법을 실험하였으며, 기존 방법보다 빠르게 ANC 시스템이 수렴하는 것을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.6
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• pp.308-316
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• 1985

A new implementation of Block Adaptive filter in frequency domain is presented in this paper. Block digital filtering involves the calculation of a block or finite set of filter out put from a block of input values. A fast convergence algorithm of block adaptive filter is developed using Gordar theory and compared with the performance results of Satio algorithm and BLMS algorithm. Form the result we can be shown that the convergence state of given algorithm is not only faster than BLMS algorithm but also the resulting convergence error is less than the convergence error of Satio algorithm.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.179-182
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• 2004

무선통신분야에서 LMS5(Least Mean Square) 알고리즘은 식이 간단하고 계산량이 비교적 적기 때문에 널리 사용되고 있다. 그러나 시간영역에서 처리할 경우 입력신호의 고유치 변동폭이 넓게 분포되어 수렴속도가 저하하는 문제점이 있다. 이를 해결하기 위하여 신호를 FFT(Fast Fourier Trasnform)나 DCT(Discrete Cosine Transform)로 변환하여 신호간의 상관도를 제거함으로써 시간영역에서 LMS알고리즘을 적용할 때 보다 수렴속도를 크게 향강시킬 수 있다. 본 논문에서는 수렴속도 향상을 위해 시간영역의 적응 알고리즘을 직교변환인 고속웨이브렛(wavelet)변환을 이용하여 변환영역에서 수행하며, 짧은 필터계수를 가지는 DWT(Discrete Wavelet Transform)특성에 맞는 Fast running FIR 알고리즘을 이용하여 WTLMS(Wavelet Transform LMS)적응알고리즘을 통신시스템에 적용한다. 적응 알고리즘의 성능향상을 위하여 시간에 따라 적응상수의 크기를 가변시켜 수렴 초기에는 큰 적응상수로 따른 수렴이 가능하도록 하고 점차 적응상수의 크기를 줄여서 misadjustment도 줄이는 방법의 적응 알고리즘을 제안하였다. 제안한 알고리즘을 실제로 적응잡음제거기(adaptive noise canceler)에 적용하여 컴퓨터 시뮬레이션을 하였으며, 각 알고리즘들의 계산량, 수렴속도를 이용하여 각각 비교, 분서하여 그 성능이 우수함을 입증하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.346-347
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• 2020

본 논문에서는 ANC 시스템의 빠른 수렴을 위한 적응 필터의 초기화 방법을 제안한다. 기존 ANC 시스템은 적응 필터의 계수를 0으로 초기화한다. 이러한 초기화 방법은 일반적으로 발생하는 외부 소음의 특성을 고려하지 않은 방법으로 ANC의 수렴 소요시간이 길다. 이와 같은 문제를 해결하고자 본 논문에서는 핑크 노이즈를 입력으로 ANC를 수행하여 얻은 적응 필터의 계수 값을 초기값으로 사용하는 새로운 초기화 방법을 제안한다. 제안한 방법으로 여러 잡음에 대해 실험한 결과, 낮은 초기 에러를 갖고 기존 방법보다 빠르게 수렴하는 것을 확인하였다. 또한, 기존 방법에서 수렴하지 못한 일부 소음에 대해서도 수렴하는 것을 확인하였다.

• Journal of the Korea Convergence Society
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• v.7 no.4
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• pp.217-227
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• 2016

This paper analyzes whether social welfare services converge across the regions. We tested whether local social welfare services converge considering the congestion rate of local social welfare services during the 1985-2013 periods in Korea, using the sixteen higher level local governments panel data. The main findings are as follows. First, the absolute level of local social welfare services converge so that the -convergence exists. Second, the growth rate of local social welfare services increases as the intial level of local social welfare services is lower so that there exists -convergence. The policy implications of our findings are as follows. The local government had better consider the presence of local social welfare services in policy decision making. Also, fundamentally the social welfare policies had better be executed by the central government rather than local governments, since the national minimum welfare must be provided.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.3
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• pp.224-229
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• 2009

In this paper, an efficient signal interference control technique to improve the convergence speed of Adaptive transversal filter with LMS algorithm is introduced. The convergence characteristics of the proposed algorithm, whose coefficients are multiply adapted in a symbol time period by recycling the received data, are analyzed to prove theoretically the improvement of convergence speed. According as the step-size parameter ${\mu}$ is increased, the rate of convergence of the algorithm is controlled. Increasing the eigenvalue spread has the effect of controlling down the rate of convergence of the adaptive equalizer and also increasing the steady-state value of the average squared error and also demonstrate the superiority of signal interference control to the filter algorithm increasing convergence speed by (B+1) times due to the data-recycling LMS Algorithms.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.1
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• pp.27-37
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• 2004

The convergence characteristics of preconditioned Euler equations were studied. A perturbation analysis was conducted to understand the behavior of the preconditioned Euler equations. Various speed flows in a two-dimensional channel with a 10％ circular arc in the middle of the channel were calculated. Roe's FDS scheme was used for spatial discretization and the LU-SGS scheme was used for time integration. It is shown that the convergence characteristics of pressure and velocity were maintained regardless of the Mach numbers but that the convergence characteristics of temperature were strongly related to the Mach number and became worse as the Mach number decreased. The perturbation analysis well explained the trend of the convergence characteristics and showed that the convergence characteristics are strongly related with the behavior o( the Preconditioning matrix.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.2
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• pp.88-94
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• 2013

In this paper, an efficient signal interference control technique to improve the convergence speed of LMS algorithm is introduced. The convergence characteristics of the proposed algorithm,whose coefficients are multiply adapted in a symbol time period by recycling the received data,are analyzed to prove theoretically the improvement of convergence speed. According as thestep-size parameter ${\mu}$ is increased, the rate of convergence of the algorithm is controlled. Increasing the eigenvalue spread has the effect of controlling down the rate of convergence of the adaptive equalizer and also increasing the steady-state value of the average squared error and also demonstrate the superiority of signal interference control to the filter algorithm increasing convergence speed by (B+1) times due to the data-recycling LMS technique.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.1-8
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• 2004

The objective of this study is convergence acceleration of multigrid Navier-Stokes solvers. This study has been performed to enhance the performance of preconditioned multi-stage time stepping method which is a popular smoother for the multigrid Navier-Stokes solvers. Comparative study on the convergence characteristics of the ADI and DDADI preconditioners has been conducted. It is shown that the DDADI preconditioner has better performance than the ADI by numerical tests on the 2-D compressible turbulent flows past airfoils. The Spalart-Allmaras turbulent model and the Baldwin-Lomax turbulent model have been compared with the multigrid calculations.