• 한국통신학회논문지
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• 제26권9B호
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• pp.1226-1235
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• 2001

The convergence analysis of the improved multiplication free adaptive digital filter (IMADF) with a fractionally-spaced equalizer (FSE) to remove the intersymbol interference (ISI) in fast data transmission is presented. The IMADF structure use the one-step predicted filter in the multiplication-free adaptive digital filter (MADF) structure using the DPCM and Sign algorithm. In the experimental results, the IMADF algorithm has reduced the computational complexity by use of only the addition operation without a multiplier. Also, under the condition of identical stationary-state error, it could obtain the stabled convergence characteristic that the IMADF algorithm is almost same as the sign algorithm, but is better than the MADF algorithm. Here, this algorithm has effective characteristics when the correlation of the input signal is highly.

• 전자공학회논문지
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• 제52권7호
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• pp.100-106
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• 2015

본 논문은 모바일 LCD 디스플레이를 위한 저전력 화질 개선의 가속화 기법을 제안한다. 제안 기법에서는 고해상도 영상을 분석 및 보정 시에 영상의 공간 해상도를 변환하고, 변환된 저해상도에서 영상의 특성을 분석하고 개선함으로써 필요한 연산량을 감소시킨다. 변환된 저해상도에서 영상에 적응적인 최적의 dimming rate을 찾아 적용함으로써 소비전력을 절감한다. 실제 안드로이드 디바이스 상에서 동작하는 어플리케이션 형태로 절전 및 화질 개선 가속화 알고리즘을 구현하였다. 디바이스상의 화질 평가 및 알고리즘 수행속도 측정을 통해 제안하는 기법이 영상의 화질저하를 최소화하는 동시에 연산량을 95% 이상 감소시킴을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.242-242
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• 2000

Comparing to the conventional adaptive filters using LMS algorithm, the proposed adaptive filters can reduce the amounts of computation and have robustness to variance of characteristics of input signals. LMS algorithm is performed in the domain of Hadamard transform after a reference signal and input signal are transformed by fast Hadamard transformation. As a transformation from time domain to Hadamard transformed domain, the proposed filter not only maintains the performance of estimating an input signal but also greatly reduces the number of multiplication. Moreover, the effect of characteristic changes of input signal is decreased. Computer simulation shows the stability and robustness of the proposed filter.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.30-35
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• 2010

As of today, Frequency Hopping techniques are widely used for over-channel interference and anti-jamming communication systems. In this paper, analysis the performance of robustness on the focus of some general jamming channel. In FH/SS systems, usually SFH(Slow Frequency Hopping) and FFH(Fast Frequency Hopping) are took up on many special communication systems, the SFH, FFH are also combined with a channel diversity algorithm likes NED(Normalized Envelop Detection), EGC(Equal Gain Combines) and Clipped Combines to overcome jammer's attack. This paper propose Adaptive-NED and shows A-NED will be worked well than the others in the some general jamming environments.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권12호
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• pp.793-798
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• 2004

In this paper, the problem of adaptively identifying time-varying nonlinear systems is considered. For that purpose, the discrete time-varying Volterra series is employed as a system model, and the filtered weighted least squares (FWLS) algorithm, developed for adaptive identification of linear time-varying systems, is utilized for the adaptive identification of time-varying quadratic Volterra systems. To demonstrate the performance of the proposed approach, some simulation results are provided. Note that the FWLS algorithm, decomposing the conventional weighted basis function (WBF) algorithm into a cascade of two (i.e., estimation and filtering) procedures, leads to fast parameter tracking with low computational burden, and the proposed approach can be easily extended to the adaptive identification of time-varying higher-order Volterra systems.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.375-379
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• 2002

본 논문에서는 수 만개이상의 미지수를 필요로 하는 복잡한 3차원 구조에서의 정전용량 추출을 위한 고속화 알고리즘(Fast mutilpole method)과 결합한 효과적인 적응 삼각요소 분할법(Adaptive triangular mesh refinement algorithm)을 제안하였다. 요소세분화과정은 초기요소로 전하의 분포를 구하고, 전하밀도가 높은 영역에서의 요소세분화를 수행하여 이루어진다. 제안된 방법을 이용하여 많은 미지수를 필요로 하는 IC packaging 구조에서의 정전용량을 추출하였다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제2권1호
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• pp.27-39
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• 1998

We describe a fast numerical method for non-separable elliptic equations in self-adjoin form on irregular adaptive domains. One of the most successful results in numerical PDE is developing rapid elliptic solvers for separable EPDEs, for example, Fourier transformation methods for Poisson problem on a square, however, it is known that there is no rapid elliptic solvers capable of solving a general nonseparable problems. It is the purpose of this paper to present an iterative solver for linear EPDEs in self-adjoint form. The scheme discussed in this paper solves a given non-separable equation using a sequence of solutions of Poisson equations, therefore, the most important key for such a method is having a good Poison solver. High performance is achieved by using a fast high-order adaptive Poisson solver which requires only about 500 floating point operations per gridpoint in order to obtain machine precision for both the computed solution and its partial derivatives. A few numerical examples have been presented.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2003년도 춘계학술발표대회논문집
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• pp.423-426
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• 2003

Adaptive algorithm used in Acoustic Echo Canceller (AEC) needs fast convergence algorithm when reference signal is colored speech signal. Set-Membership Affine Projection (SMAP) algorithm is derived from the constraint, which is the minimum value adaptive filter coefficient error. In this paper, we test the characteristic about noise of the SMAP algorithm and proposed modified version of SMAP algorithm fur using at AEC. As the projection order increase, the convergence characteristic of the SMAP algorithm is improved where no noise space. But if the noise uncorrelated with input signal exists, the AEC shows bad performance. In this paper, we propose normalized version of adaptive constants using estimated error signal for robust to noise and show the good performance through AEC simulation.

• 한국음향학회지
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• 제22권4호
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• pp.293-298
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• 2003

본 논문에서는 NNVQ (nearest neighbor vector quantization)를 위한 고속탐색 알고리듬을 제안하였다. 제안된 알고리듬은 입력 벡터 내 지정된 요소의 부호화 왜곡을 임계값과 비교해서 최적 코드워드가 될 가능성이 없는 코드워드를 탐색 대상 코드워드에서 제외함으로써 코드북 탐색의 범위를 줄인다. 이를 통해 기존의 풀서치(full-search) 알고리듬과 동일한 SD(spectral distortion) 성능을 얻으면서 부호화 과정에서의 처리시간과 복잡도를 감소시킨다. 제안된 알고리듬을 Gauss-Markov 소스에 대해 설계된 일반적인 벡터 양자화기와 3GPP에서 표준화된 AMR (adaptive multi-rate) 음성 코덱의 LSP 양자화기에 각각 적용하여 실험하였다. 실험결과 제안된 알고리듬은 SD 성능감쇄 없이 탐색 대상 범위를 감소시킴으로써 부호화시 복잡도를 50%이상 줄일 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.218-220
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• 2004

Orthogonal frequency division multiplexing(OFDM) is one of the most promising technique for next generation wireless broadband communication systems. In this paper, we propose a new bit allocation algorithm in multiuser OFDM. The proposed algorithm is derived from the geometric progression of the additional transmit power of subcarriers and the arithmetic-geometric means inequality. The simulation shows that this algorithm has similar performance to the conventional adaptive bit allocation algorithm and lower computational complexity than the existing algorithms.