• 디지털융복합연구
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• 제10권5호
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• pp.233-238
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• 2012

유성음원과 무성음원을 시용하는 음성부호화 방식에 있어서, 같은 프레임 안에 모음과 무성자음이 있는 경우에 음성 파형에 일그러짐이 나타난다. 이것을 해결하기 위하여 본 논문에서는 개별피치와 LMS(Least Mean Square)를 적용한 LMS-MPC를 제시하였으며, 기존의 MPC와 LMS-MPC의 SNRseg를 평가한 결과, LMS-MPC의 남자음성에서 1.5dB, 여자음성에서 1.3dB 개선된 것을 확인할 수 있었다. 결국, MPC에 비해 LMS-MPC의 SNRseg가 개선되어 음성파형의 일그러짐을 제어할 수 있었으며, 본 방법은 셀룰러폰이나 스마트폰과 같이 Low Bit Rate의 음원을 사용하여 음성신호를 부호화 하는 방식에 활용할 수 있을 것으로 기대된다.

• Educational Technology International
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• 제25권1호
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• pp.67-92
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• 2024

This study aims to verify the practical effectiveness of learning management system (LMS) by introducing a LMS enhancing digital assessment utilizing automatic item generation in order to strengthen college student's mathematics performance. Teaching assisted with digital assessment in the LMS was applied to college mathematics classes, and the research question is whether or not students in the classes utilizing the LMS perform better than the regular classes. In particular, a calculus course, which is the foundation of important artificial intelligence technology in the future, was utilized in this study. The participants of this study were 248 freshmen in science and engineering who were taking calculus courses at a small to mid-size university. A total of 156 freshmen were selected after applying a propensity score matching method (PSMM), 78 from classes utilizing the LMS and 78 from regular classes without the LMS assisted with the digital assessment. As a result, it was found that there was a statistically significant difference in the math academic growth of students who used the LMS and those who did not. In other words, when LMS was used in calculus, students' academic growth was greater. The results of this study are meaningful in that they observed students' academic growth and confirmed that LMS enables a positive role in students' academic growth. In addition, if digital assessment is strengthened and LMS that enables individualized learning analysis is introduced and implemented in educational institutions, it is expected to play a major role in strengthening students' academic performance.

• 전기전자학회논문지
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• 제6권2호
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• pp.111-118
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• 2002

본 논문은 가변 스텝사이즈 LMS (Least Mean Square) 알고리듬의 스텝사이즈 결정시 추가되는 계산량을 줄이기 위해 가변 블록을 사용하는 방법을 제안한다. 이 방법에서는 블록 길이를 스텝사이즈의 변화에 반비례하도록 하여 기존의 가변 스텝사이즈 알고리듬의 수렴속도와 정상상태 오차에 대해 성능의 저하 없이 계산량을 줄이고자 한다. 그리고 평균이 영인 백색 가우시안 입력신호 환경하에서 LMS 기반 적응 알고리듬의 초기 스텝사이즈를 최적으로 구하는 방법을 제안한다. 제안한 방법의 우수성을 입증하기 위한 컴퓨터 모의 실험을 통해 기존의 가변 스텝사이즈 알고리듬과 수렴속도, 계산량 면에서 성능을 평가한다.

• Journal of electromagnetic engineering and science
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• 제4권1호
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• pp.23-29
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• 2004

In this paper we analyze convergence constraints and time constant of IT-LMS algorithm and derive a method of making it's time constant independent of signal power by using input variance estimation. The method for estimating the input variance is to use a single-pole low-pass filter(LPF) with common smoothing parameter value, θ. The estimator is with narrow bandwidth for large θ but with wide bandwidth for small θ. This small θ gives long term average estimation(low frequency) of the fluctuating input variance well as short term variations (high frequency) of the input power. In our simulations of multipath communication channel equalization environments, the method with large θ has shown not as much improved convergence speed as the speed of the original IT-LMS algorithm. The proposed method with small θ=0.01 reach its minimum MSE in 100 samples whereas the IT-LMS converges in 200 samples. This shows the proposed, tap-power normalized IT-LMS algorithm can be applied more effectively to digital wireless communication systems.

• 한국전자통신학회논문지
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• 제18권3호
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• pp.535-544
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• 2023

본 논문에서는 희망하는 빔포밍을 실현하기 위하여 LMS 알고리즘(반복법)을 이용하는 경우에 반복 계산과정에서 무게 분포를 조절하기 위한 기울기 벡터의 계산법(해석적인 방법, 중앙유한차분법)이 적응 빔포밍에 미치는 영향을 연구하였다. 이를 위하여 임의로 설정한 빔폭을 갖는 준이상 빔과 회전 빔, 그리고 멀티 빔을 예로 하여 검토하였다. 수치 실험은 적응 빔포밍 시스템에 임의의 초기치와 시행착오를 거쳐서 설정한 적절한 값의 스텝 파라미터를 두 계산법에 동일하게 적용하고, 기울기 벡터의 계산을 위한 두 가지 방법을 이용하여 적응성과 오차를 평가하는 목적 함수의 수렴 특성 등을 비교하였다.

• 전기학회논문지P
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• 제65권3호
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• pp.171-177
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• 2016

Noise problem that occurs in living environment is a big trouble in the economic, social and environmental aspects. In this paper, the filtered-X LMS algorithms, the adjoint LMS algorithms, and the robust adjoint LMS algorithms will be introduced for applications in active noise control(ANC). The filtered-X LMS algorithms is currently the most popular method for adapting a filter when the filter exits a transfer function in the error path. The adjoint LMS algorithms, that prefilter the error signals instead of divided reference signals in frequency band, is also used for adaptive filter algorithms to reduce the computational burden of multi-channel ANC systems such as the 3D space. To improve performance of the adjoint LMS ANC system, an off-line measured transfer function is connected parallel to the LMS filter. This parallel-fixed filter acts as a noise controller only when the LMS filter is abnormal condition. The superior performance of the proposed system was compared through simulation with the adjoint LMS ANC system when the adaptive filter is in normal and abnormal condition.

• 소음진동
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• 제4권1호
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• pp.59-69
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• 1994

A new LMS algorithm titled constrained LMS' is proposed for problems with constrained structure. The conventional LMS algorithm can not be used because it destroys the constrained structures of the weights or parameters. Proposed method uses error-back propagation, which is popular in training neural networks, for error minimization. The illustrative examplesare shown to demonstrate the applicability of the proposed algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.689-692
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• 2003

In this paper, we propose an adaptive beamforming algorithm for array antenna. The proposed beamforming algorithm, based on Block LMS (Block - Least Mean Squares) algorithm, has a variable step size from coefficient update. This method shows some advantages that the convergence speed is fast and the calculation time can reduced using a block LMS algorithm from frequency domain. As the adaptive parameter approaches a stationary state, it could reduce the number of filter coefficient update with the help of various step size. In this paper we compared the efficiency of the proposed algorithm with a standard LMS algorithm which is a representative method of adaptive beamforming.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.82-85
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• 2012

본 논문은 천리안 위성을 이용하여 운용중인 공공 테스트베드의 가용율 및 시스템 throughput 향상을 위해 포워드 링크 ACM(Adaptive Coding & Modulation) 방안에 대해 소개하고, 포워드링크에 ACM 기능을 구현하기 위한 채널 상태를 예측하기위한 알고리즘으로 기울기를 이용한 예측 기법과 LMS(Least Mean Square)를 이용한 예측 기법의 성능을 비교하였다. 시뮬레이션 결과 LMS 기법을 이용한 예측기법은 99%가 3dB 이내의 예측 오차를 보였고, 기울기를 이용한 예측 기법은 99%가 4.5dB 이내의 예측 오차를 갖음을 알 수 있다.

• 한국음향학회지
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• 제12권1호
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• pp.37-46
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• 1993

The adaptive algorithm for the Volterra filter is considered. Owing to its simplicity, the LMS algorithm for adaptive Volterra filter(AVF) is widely used as in linear adaptive filters. However, the convergence speed is unsatisfactory. For improving the convergence speed, the frequency domain LMS second order adaptive Volterra filter(FLMS-AVF) is proposed and analyzed. We show that the time and frequency domain LMS AVF's have the same steady state performance under approprate conditons. Moreover, it can be shown that this algorithm can improve the convergence speed significantly by applying self-orthogonalizing method.