• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1996년도 춘계학술대회
• /
• pp.14-17
• /
• 1996

Evoked Potentials signals occur as a result of neuroelectric responses of the brain to sensory stimulation. In this paper, to analysis such signals we utilize a time-frequency analysis technique called wavelet transform. The wavelet analysis is performed based on a single prototype function,which can be thought of as a bandpass filter. Because the wavelet transform in a fine temporal analysis decomposes time-varying signals in EP into a dilated lowpass and a contracted highpass components, EP signal fetures can be obtained and analysed quantitatively at the levels of resolution. In the results, we analyze the VEP signal with the wavelet transform.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제50권3호
• /
• pp.149-157
• /
• 2001

In the video retrieval system, visual clues of still images and motion information of video are employed as feature vectors. We generate the temporal textures to express the motion information whose properties are simple expression, easy to compute. We make those temporal textures of wavelet coefficients to express motion information, M components. Then, temporal texture feature vectors are extracted using spatial texture feature vectors, i.e. spatial gray-level dependence. Also, motion amount and motion centroid are computed from temporal textures. Motion trajectories provide the most important information for expressing the motion property. In our modeling system, we can extract the main motion trajectory from the temporal textures.

• 대한전자공학회논문지SP
• /
• 제41권4호
• /
• pp.39-44
• /
• 2004

움직임 보상을 고려한 3차원 웨이블릿 변환은 공간적, 시간적인 상관관계에 중복된 정보를 효과적으로 제거한다. 그러나 웨이블릿 방식으로 압축된 영상이라 하더라도 압축률이 높은 경우 고주파 서브밴드의 변환계수가 상당수 손실되어 압축복원 시에 링 현상과 같은 왜곡이 생긴다. 본 논문에서는 이러한 3차원 웨이블릿의 압축왜곡을 줄이기 위하여 적응적 반복 복원 기법을 사용하는 새로운 알고리듬을 제안하였다. 제안된 적응적 기법에서는 에지의 방향에 따라 서로 다른 고역통과필터를 정칙화 복원에 사용하였다.

• 대한음성학회지:말소리
• /
• 제61호
• /
• pp.63-74
• /
• 2007

Discrimination of music and speech from the multimedia signal is an important task in audio coding and broadcast monitoring systems. This paper deals with the problem of feature parameter extraction for discrimination of music and speech. The wavelet transform is a multi-resolution analysis method that is useful for analysis of temporal and spectral properties of non-stationary signals such as speech and audio signals. We propose new feature parameters extracted from the wavelet transformed signal for discrimination of music and speech. First, wavelet coefficients are obtained on the frame-by-frame basis. The analysis frame size is set to 20 ms. A parameter $E_{sum}$ is then defined by adding the difference of magnitude between adjacent wavelet coefficients in each scale. The maximum and minimum values of $E_{sum}$ for period of 2 seconds, which corresponds to the discrimination duration, are used as feature parameters for discrimination of music and speech. To evaluate the performance of the proposed feature parameters for music and speech discrimination, the accuracy of music and speech discrimination is measured for various types of music and speech signals. In the experiment every 2-second data is discriminated as music or speech, and about 93% of music and speech segments have been successfully detected.

• 산업기술연구
• /
• 제25권B호
• /
• pp.89-97
• /
• 2005

Application of proper orthogonal decomposition (POD) and continuous wavelet transform (CWT) is introduced to study wind speed and building roof pressures of flow separation region. In this study, a detailed analysis of the approach wind flow, wind-induced building pressure and the relation between the two fields was carried out using the POD technique and CWT analysis. The results show potential of the application of POD and CWT in characterization of spatio-temporal and spectral properties of the approach wind and its induced dynamic pressure events. Some of findings resulting from the application of this analysis can be summarized as follows: (1) The POD first principal coordinate of the roof pressure in the separated shear layer is closely correlated with the longitudinal component of oncoming flow. (2) The CWT analysis suggests that the extreme peak pressure in the separated shear layer is due to condensed large-scale eddy motions.

• 한국통신학회논문지
• /
• 제21권5호
• /
• pp.1096-1108
• /
• 1996

In this paper, we propose a temporal adaptive tranform 3D SBC coder with motion compensation, exploiting redundancy in the temporal domain. We propose a temporal adaptivity measure, by which the R-D optimal temporal transform can be chaosen. The base temporal subband frame is coded using H.261-like MC-DCT coder, while the higher temporal subband frames are coded using the 2D adaptive wavelet packet bases, considering the various energy distribution which results from the temporal variation. In encoding the subbands, we employ adaptive scanning methods, uniform step-size quantization with VLC, and coded/not-coded flag reduction technique using the quadtree structure. From the simulation results, the proposed adaptive 3D subband coder shows about 0.29~3.14 dB gain over the H.261 and the fixed 3D subband coder techniques.

• 대한전자공학회논문지TC
• /
• 제47권8호
• /
• pp.85-90
• /
• 2010

본 논문에서는 디지털 주파수 판별기 (digital frequency discriminator)와 웨이블릿 변환 (wavelet transform)을 이용한 주파수 도약 확산 스펙트럼 시스템 (frequency hopping spread spectrum systems) 신호의 도약 시간 (hop timing)과 도약 주기(hop duration)를 블라인드 (blind)로 추정하는 알고리듬을 제안한다. 제안하는 알고리듬은 기존에 제안된 시간 상관함수(temporal correlation function) 기반 도약 시간 추정 알고리듬에 비하여 구현 복잡도가 낮을 뿐만 아니라 추정 성능이 우수하다.

• 한국멀티미디어학회논문지
• /
• 제17권3호
• /
• pp.287-293
• /
• 2014

인명과 물질적 손실을 줄이기 위해서는 화재의 조기 감지는 매우 중요하다. 비디오 기반의 연기 감지방법은 야외에서 연기 감지의 어려움이 있는 기존의 센서 기반의 연기 감지 방법의 단점을 극복할 수 있다. 본 논문에서는 비디오 기반의 새로운 연기 감지 방법을 제안한다. 제안한 방법은 웨이블릿 변환 영역에서 각 부대역의 에너지의 비율을 이용하여 연기 영역을 검출한다. 잘못된 연기 검출을 감소시키기 위하여 YUV 칼라 공간에서 움직임, 색도의 감소, 블록의 명도를 이용하여 후보 연기 블록을 검출한다. 최종적으로, 웨이블릿 변환 영역에서 후보 연기 블록에 대한 부대역 에너지의 시간적 변화를 이용하여 연기 블록을 결정한다. 실험을 통하여 제안한 방법이 기존의 웨이블릿을 이용한 연기 감지 방법보다 연기의 검출율과 오검출율이 현저히 향상되는 것을 확인하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
• /
• pp.841-844
• /
• 2001

This paper introduces a new technique for estimating the speed of a mobile station in a wireless system. The proposed method is based on the feature extraction of the received signal envelope. The undecimated discrete wavelet transform via lifting captures local minimum points of the received signal, which is used for the speed estimation. This technique requires neither knowledge of the average received power of the nonstationary signal nor adaptation of a temporal observation window, in contrast to other speed estimators given in the literature. Simulations show that the proposed speed estimator tracks the variable speed of the mobile station.

• International Journal of Computer Science & Network Security
• /
• 제22권2호
• /
• pp.123-130
• /
• 2022

During the past decades, detection of gear defects remains as a major problem, especially when the gears are subject to non-stationary phenomena. The idea of this paper is to mixture a multilevel wavelet transform with a fast EMD decomposition in order to early detect gear defects. The sensitivity of a kurtosis is used as an indicator of gears defect burn. When the gear is damaged, the appearance of a crack on the gear tooth disrupts the signal. This is due to the presence of periodic pulses. Nevertheless, the existence of background noise induced by the random excitation can have an impact on the values of these temporal indicators. The denoising of these signals by multilevel wavelet transform improves the sensitivity of these indicators and increases the reliability of the investigation. Finally, a defect diagnosis result can be obtained after the fast transformation of the EMD. The proposed approach consists in applying a multi-resolution wavelet analysis with variable decomposition levels related to the severity of gear faults, then a fast EMD is used to early detect faults. The proposed mixed methods are evaluated on vibratory signals from the test bench, CETIM. The obtained results have shown the occurrence of a teeth defect on gear on the 5th and 8th day. This result agrees with the report of the appraisal made on this gear system.