• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.159-162
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• 2010

This paper presents a new Kurtosis driven Variable Step-Size Normalized Least Mean Square (KVSSN-LMS) algorithm to prevent repeater from oscillation due to feedback signal of radio frequency (RF) repeater. To get better Mean Square Error (MSE) performance, step-size is adjusted using the kurtosis. The proposed algorithm shows the better performance of steady state MSE. The proposed algorithm shows a better ERLE performance than that of KVSS-LMS, VSS-NLMS, NLMS algorithms.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.224-227
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• 1993

In this paper, a new LMS algorithm with a variable step size (VVS LMS) is presented. The change of step size .mu. at each iteration, which increases or decreases according to the misadaptation degree, is computed by a proportional fuzzy logic controller. As a result the algorithm has very good convergence speed and low steady-state misadjustment. The norm of the cross correlation between the estimation error and input signal is used. As a measure of the misadaptation degree. Simulation results are presented to compare the performance of the VSS LMS algorithm with the normalized LMS algorithm.

• 산업기술연구
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• 제13권
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• pp.33-41
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• 1993

In this paper, a new LMS algorithm with a fuzzy variable step size (FVS LMS) is presented. The change of step size ${\mu}$, at each iteration which is increases or decreases according to the misadaptation degree, is computed by a proportional fuzzy logic controller. As a result the algorithm has very good convergence speed and low steady-state misadjustment. As a measure of the misadaptation degree, the norm of the cross correlation between the estimation error and input signal is used. Simulation results are presented to compare the performance of the FVSS LMS algorithm with the normalized LMS algorithm.

• Journal of Power Electronics
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• 제12권1호
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• pp.164-171
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• 2012

Variable step size maximum power point trackers (MPPTs) are widely used in photovoltaic (PV) systems to extract the peak array power which depends on solar irradiation and array temperature. One essential factor which judges system dynamics and steady state performances is the scaling factor (N), which is used to update the controlling equation in the tracking algorithm to determine a new duty cycle. This paper proposes a novel stability study of variable step size incremental resistance maximum power point tracking (INR MPPT). The main contribution of this analysis appears when developing the overall small signal model of the PV system. Therefore, by using linear control theory, the boundary value of the scaling factor can be determined. The theoretical analysis and the design principle of the proposed stability analysis have been validated using MATLAB simulations, and experimentally using a fixed point digital signal processor (TMS320F2808).

• Journal of Power Electronics
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• 제14권1호
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• pp.156-164
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• 2014

The power-voltage (P-V) characteristic of a photovoltaic (PV) array is nonlinear and time varying with the change in atmospheric conditions. As a result, the maximum power point tracking (MPPT) technique must be applied in PV systems to maximize the generated energy. The incremental conductance (INC) algorithm, one of the MPPT strategies, is widely used for its high tracking accuracy, good adaptability to rapidly changing atmospheric conditions, and easy implementation. This paper presents a modified asymmetrical variable step size INC MPPT method that is based on the asymmetrical feature of the P-V curve. Compared with conventional fixed or variable step size method, the proposed method can effectively improve tracking accuracy and speed. The theoretical foundation and design principle of the proposed approach are validated by the simulation and experimental results.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.7-11
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• 2015

In this paper, an automatic focusing method has been proposed for speedy and reliable measurement and inspection in industry. It is very difficult to determine focusing step size and moving direction in one camera autofocusing. The proposed method can improve speed and accuracy of focusing by using the optical axis interval of two cameras, which is automatically set up as focusing step size. Also, it can determine moving direction from focus value comparisons of two cameras, and then solve ambiguity of one camera focusing. Its performance is verified by experiments. It is expected that it can apply to optical system for measurement and inspection in industry fields.

• 한국멀티미디어학회논문지
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• 제8권6호
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• pp.753-760
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• 2005

This paper introduces a variable step-size adaptive algorithm for blind source separation. From the frequency characteristics of mixed input signals, we need to adjust the convergence speed regularly in each frequency bin. This algorithm varies a step-size according to the magnitude of input at each frequency bin. This guarantee of the regular convergence in each frequency bin would become more efficient in separation performances than conventional fixed step-size FDICA. Computer simulation results show the improvement of about 5 dB in signal to interference ratio (SIR) and the better separation quality.

• 한국인터넷방송통신학회논문지
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• 제16권3호
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• pp.89-95
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• 2016

본 논문에서는 결정 지향 오차 신호의 크기 값을 이용하여 두개의 블라인드 등화 알고리즘이 자동으로 전환되는 이중 모드 블라인드 등화 알고리즘을 제안한다. 제안한 알고리즘은 등화초기에는 주로 큰 고정 스텝 크기를 가지는 MSAGF-SMMA를 통하여 보다 빠른 수렴 속도를 얻도록 하고, 어느 정도 등화가 이루어진 시점부터는 주로 가변 스텝 크기를 가지는 MSAGF-SMMA가 동작하도록 함으로써 정상상태에서 보다 작은 잔류 오차를 얻도록 하였다. 가변 스텝 크기는 고정 스텝 크기에 결정 지향 오차 신호의 크기 값을 곱하여 구한다. 본 논문에서 제안한 알고리즘에 대한 성능을 분석하였다. 컴퓨터 모의실험을 통하여 제안한 알고리즘이 MMA, SMMA, 그리고 MSAGF-SMMA에 비해 정상상태에서의 잔류 심볼간 간섭과 잔류 오차 등에서 크게 향상된 성능을 가짐을 확인하였다.

• 한국음향학회지
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• 제33권5호
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• pp.309-315
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• 2014

본 논문은 능동 소음 제어 시스템에 적합한 새로운 가변 수렴 상수 filtered-x gradient adaptive lattice(NVSS-FxGAL) 알고리즘을 제안한다. Gradient adaptive lattice(GAL) 알고리즘은 협대역 특성을 가지는 소음을 효과적으로 제어할 수 있다. GAL 알고리즘의 수렴 성능을 개선하기 위한 가변 격자 필터의 각 단계에 동일하게 적용하면 입력 신호의 특성 변화에 강인하게 대처하지 못한다. 제안 알고리즘은 격자 필터의 각 단계에 적합한 로컬 가변 수렴상수를 이용하여 안정적이고 일관성 있는 수렴 성능을 보장한다. 실험을 통해 제안 알고리즘은 빠른 수렴 속도와 낮은 정상 상태를 보임을 확인하였다.

• 전기전자학회논문지
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• 제23권4호
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• pp.1430-1439
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• 2019

FMI를 기반으로 하는 co-simulation의 마스터 알고리즘(MA)에서 시뮬레이션 결과의 정확도를 높이는 방법으로 zero crossing 포인트를 찾기 위한 Bisectional algorithm을 사용할 수 있다. 그러나 이 알고리즘은 많은 Rollback을 야기한다. 따라서 본 논문에서는 제안하는 MA는 Bisection algorithm을 통해 zero crossing 포인트를 검출하면서도 반복되는 구간 그래프를 분석하여 그 값을 Markov chain을 적용하여 다음 구간을 예측하여 이를 step size에 적용한다. 시뮬레이션에서 실제 Rollback이 발생했을 때 그래프 형태별로 변화되는 step size를 배열로 저장하고, 이룰 다음 예측 구간에 적용함으로서 Rollback을 최소화하는 알고리즘을 제안한다. 시뮬레이션 결과를 통해 제안하는 알고리즘이 기존 알고리즘에 비해 최대 20% 이상의 시뮬레이션 시간이 감소되는 것을 확인하였다.