• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.290-291
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• 2008

The most popular speech feature used in speech recognition today is the Mel-Frequency Cepstral Coefficients (MFCC) algorithm, which could reflect the perception characteristics of the human ear more accurately than other parameters. This paper adopts MFCC and its first order difference, which could reflect the dynamic character of speech signal, as synthetical parametric representation. Furthermore, we quote Dynamic Time Warping (DTW) algorithm to search match paths in the pattern recognition process. We use the software "GoldWave" to record English digitals in the lab environments and the simulation results indicate the algorithm has higher recognition accuracy than others using LPCC, etc. as character parameters in the experiment for Digital Isolated Word Recognition (DIWR) system.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 추계학술발표논문집
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• pp.1010-1013
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• 2009

본 논문에서는 STFT을 이용한 이두박근의 근전도 신호 근피로도 측정 방법을 제시한다. 개선된 STFT방식은 기존연구에서 사용되어져 왔던 중간주파수를 이용한 근피로도 측정 방법과 달리 STFT를 이용한 시간, 주파수 평면에서 2차원 영상을 이용하여 근피로도를 측정할 수 있는 방법이다. 제안한 방법은 이두박근에서 수집한 근전도 신호의 근피로도 측정에 사용하여 제안한 방법의 타당성을 검증하였다.

• 한국소음진동공학회논문집
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• 제24권4호
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• pp.324-331
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• 2014

The sensor configuration of the magnetostrictive guided wave system can be described as a single continuous transducing element which makes it difficult to separate the individual modes from the reflected signal. In this work we develop the mode decomposition technique employing chirplet transform based on the maximum likelihood estimation, which is able to separate the individual modes from dispersive and multimodal waveform measured with the magnetostrictive sensor, and estimate the time-frequency centers and individual energies of the reflection, which would be used to locate and characterize defects. Simulation results on a carbon steel pipe are presented, which show the accurate mode separation and more discernible time-frequency representation could become enabled using the proposed technique.

• 전자공학회논문지A
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• 제32A권9호
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• pp.1244-1249
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• 1995

Wavelet transform technique is applied to two important electromagnetic problems:1) to analyze the frequency-domain radar echo from finite-size targets and 2) to the integral solution of two- dimensional electromagnetic scattering problems. Since the frequency- domain radar echo consists of both small-scale natural resonances and large-scale scattering center information, the multiresolution property of the wavelet transform is well suited for analyzing such ulti-scale signals. Wavelet analysis examples of backscattered data from an open- ended waveguide cavity are presented. The different scattering mechanisms are clearly resolved in the wavelet-domain representation. In the wavelet transform domain, the moment method impedance matrix becomes sparse and sparse matrix algorithms can be utilized to solve the resulting matrix equationl. Using the fast wavelet transform in conjunction with the conjugate gradient method, we present the time performance for the solution of a dihedral corner reflector. The total computational time is found to be reduced.

• ETRI Journal
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• 제33권6호
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• pp.945-948
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• 2011

Object-based audio coding can provide new music applications with interactivity. To efficiently compress a lot of target audio objects, a subband-based parametric coding scheme has been adopted for MPEG spatial audio object coding. In this letter, the time-frequency (T/F) subband analysis structure is investigated. A reconfigured T/F structure is also proposed to enhance the generating performance of sound scenes such as 'karaoke' and 'solo' play in interactive music scenarios. From the experimental results, it was confirmed that the proposed scheme remarkably improves the SNR and sound quality.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.190-199
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• 2014

In the last years, fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. The fault problem can cause equipment failure, data and economical losses. And the analyze system require to ensure fault problem and also rectify failures. The current errors on these faults are applied for identified type of faults. This paper presents technique to detection and identification faults in three-phase voltage source inverter (VSI) by using time-frequency distribution (TFD). TFD capable represent time frequency representation (TFR) in temporal and spectral information. Based on TFR, signal parameters are calculated such as instantaneous average current, instantaneous root mean square current, instantaneous fundamental root mean square current and, instantaneous total current waveform distortion. From on results, the detection of VSI faults could be determined based on characteristic of parameter estimation. And also concluded that the fault detection is capable of identifying the type of inverter fault and can reduce cost maintenance.

• 대한전기학회논문지
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• 제34권1호
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• pp.29-37
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• 1985

During Severe emergencies which result in the case of outage of large generator units, an automatic underfrequency protection scheme can prevent the system frequency from decaying and improve the system stability. This paper presents methods and results of a study on the optimum load shedding scheme which covering as follows. 1) Detail representation of governor model 2) Determination of optimum load shedding amount 3) Selection of action time settings of UFR 4) Comparsson of load shedding programs By this study, the optimum system operating method was recommended for reliable operation of power system.

• 대한의용생체공학회:의공학회지
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• 제9권1호
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• pp.135-138
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• 1988

In this paper, computerized BEAM was implemented for the space domain analysis of EEG. Trans-formation from temporal summation to two-dimensional mappings is formed by 4 nearest point inter-polaton method. Methods of representation of BEAM are two. One is dot density method which classify brain electrical potential 9 levels by dot density of gray levels and the other is colour method which classify brain electrical 12 levels by red-green colours. In this BEAM, instantaneous change and average energy distribution over any arbitrary time interval of brain electrical activity could be observed and analyzed easily. In the frequency domain, the distribution of energy spectrum of a special band can easily be distinguished normality and abnormality.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (B)
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• pp.34-36
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• 2006

In this paper we present a method of feature extraction for motor imagery single trial EEG classification, where we exploit nonnegative matrix factorization (NMF) to select discriminative features in the time-frequency representation of EEG. Experimental results with motor Imagery EEG data in BCI competition 2003. show that the method indeed finds meaningful EEG features automatically, while some existing methods should undergo cross-validation to find them.

• Korean Journal of Mathematics
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• 제27권1호
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• pp.1-8
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• 2019

We will deal with an n locus model in which mutation and gene conversion are taken into consideration. Also random partitions of the number n determined by chromosomes with n loci should be investigated. The diffusion process describes the time evolution of distributions of the random partitions. In this paper, we find the probability of distribution of the diffusion process with special diffusion operator $L_1$ and we show that the average probability of genes at different loci on one chromosome can be described by the rate of gene frequency of mutation and gene conversion.