• Title/Summary/Keyword: 고속퓨리에 변환

Search Result 34, Processing Time 0.024 seconds

A Study on Local Filtering of Signal in Wavelet Plane (웨이브렛 평면에서 신호의 국부 필터링에 관한 연구)

  • Bae Sang-Bum;Kim Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2006.05a
    • /
    • pp.477-480
    • /
    • 2006
  • To represent the accurate feature of signal and system, many researches have been done in many fields of basic and engineering science which led a great development of modem society. Even until currently, in order to acquire useful information from signals at high speed, many methods and transforms have been processed. In these methods, the Fourier transform which represents signal as the combination of the frequency component has been applied to the most fields. But as transform not to consider time information, the Fourier transform does not provide time information of the time and presents only overall features of signals. The wavelet transform, which is proposed to overcome this problem and recently expands the range of the application, presents time-frequency localization and many kinds of the wavelet can be applied according to the environment of application. In this paper, we detect the features of signals using the function which is considered as the wavelet and do research for filtering locally in the wavelet plane.

  • PDF

A Study of Roughness Measurement of Rock Discontinuities Using a Confocal Laser Scanning Microscope (콘포컬 레이저 현미경을 이용한 불연속면의 거칠기 측정 연구)

  • Byung Gon Chae;Jae Yong Song;Gyo Cheol Jeong
    • The Journal of Engineering Geology
    • /
    • v.12 no.4
    • /
    • pp.405-419
    • /
    • 2002
  • Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

Background Music Identification in TV Broadcasting Program Algorithm using Audio Peak Detection (오디오 피크 검출을 적용한 TV 방송 프로그램 내 배경음악 식별 알고리즘)

  • Lee, Jung-Sung;Kim, Hyoung-Gook
    • Proceedings of the Korean Society of Broadcast Engineers Conference
    • /
    • 2013.06a
    • /
    • pp.34-35
    • /
    • 2013
  • 본 논문에서는 오디오 피크 검출을 적용한 TV 방송 프로그램내 배경음악 식별 알고리즘을 제안한다. 제안한 알고리즘은 음악 핑거프린트 추출 및 전송부, 음악구간 검출부, 음악 핑거프린트는 고속 매칭 및 정보전송부 세 부분으로 구성되어 있다. 음악 핑거프린트 추출 및 전송부에서는 음악 원음 오디오 데이터를 퓨리에 변환하여 스펙트럼 계수를 추출한다. 추출된 스펙트럼의 성분 중에서 일정한 문턱값 이상의 에너지를 가지는 값을 피크로 검출하고 검출된 피크를 이용하이 핑거프린트를 생성하고 데이터 베이스화한다. 음악구간 검출부에서는 입력된 방송 프로그램 오디오 데이터에 GMM(Gaussian Mixture Model)을 적용하여 음악과 음악 외 오디오 데이터를 분류한다. 음악 핑거프린트 고속 매칭 및 정보전송부에서는 음악구간이라고 인식된 쿼리 오디오 데이터를 음악 핑거프린트 추출 및 전송부와 동일한 과정을 통해 핑거프린트를 생성하고 데이터 베이스화된 음악 원음의 핑거프린트들과 비교하여 가장 유사한 음원의 정보를 TV의 화면에 자막으로 보여준다.

  • PDF

Wireless Transmitter earpiece for Sensibility Ergonomics (감성공학을 위한 무선 이어폰 전송 장치)

  • Lim, Chae-Young;Jeon, Ki-Man;Kim, Kyung-Ho
    • Proceedings of the Korean Society of Computer Information Conference
    • /
    • 2011.06a
    • /
    • pp.273-276
    • /
    • 2011
  • 우리는 감성 공학에 기반하여 일상 생활 속에서 비침습적이면서 사용하기 간편한 광전용적맥파신호를 계측하고 분석하는 이어폰형 생체 신호 측정 시스템에 관하여 연구하였다. 생체 신호 측정 시스템에서는 광전용적맥파(photoplethysmograph, PPG)와 3축 가속도로 생체 신호와 운동 신호를 활용하였다. 수신된 생체 신호인 광전용적맥파 신호는 Peak 검출 및 전처리 알고리즘을 통하여 심박동변동성(heart rate Variablity,HRV)에 대한 시계열 정보로 변환하고 고속 퓨리에 변환(Fast Fourier Transfirm, FFT)과 전력 스펙트럼 밀도 분석(Power Spectrum Density, PSD)방법으로 교감과 부교감 신경 활성도 변화를 관측하였고, 운동 센서로 움직임을 관측하였다. 수신부 시스템은 안드로이드 기반의 자바 어플리케이션으로 스마트 폰에서 구현하였고, 송신부인 이어폰 생체정보 측정모듈로 맥파를 측정하여 상황에 따라 변화하는 자율 신경계의 활성도비율을 확인하였다.

  • PDF

Measurement of natural frequency of aluminum honeycomb sandwich beams using high speed digital cameras (고속 디지털 카메라를 이용한 알루미늄 하니콤 샌드위치 보의 고유 진동수 계측)

  • Goo, Nam Seo;Vang, Hoang My;Le, Vinh Tung;Jin, Tailie
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.45 no.1
    • /
    • pp.30-35
    • /
    • 2017
  • In this study, we measured the natural frequencies of aluminum honeycomb sandwich beams using digital image correlation technique. The vibration images were captured using two high speed digital cameras and the images were converted to displacements by the digital image correlation technique. Displacement data in time domain were tranformed to frequency domain data by fast Fourier transform software. To reduce noise invoked by random exitation, a spectrum averaging technique and Savitsky-Golay digital filter were adopted. A conventional vibration measurement using an accelerometer and a finite element analysis were performed to compare the results by high speed digital camera measurement method. In conclusion, new method using high speed digital cameras and digital image correlation technique can measure the vibration of beam structures and can be applied to bio-structures where sensors cannot be attached.

The Efficient Eye Image Check Algorithm for The Robust Iris Recognition System (강인한 홍채 인식 시스템을 위한 효율적인 눈 영상 검사 알고리즘)

  • 장자인;김귀주;손진호;이일병
    • Proceedings of the Korean Information Science Society Conference
    • /
    • 2003.04c
    • /
    • pp.328-330
    • /
    • 2003
  • 홍채 인식 시스템의 성능향상을 위해서는 전처리 단계에서 위조된 데이터나 잡음이 섞인 데이터를 걸러내는 과정이 매우 중요하다. 이 논문에서는, 강인한 홍채 인식 시스템을 위해서 두 단계로 이루어진 눈 영상 검사 알고리즘을 제안한다. 알고리즘의 첫 번째 단계에서는 동공 반지름과 눈꺼풀 움직임 변화량의 상관계수(coefficient)와 2차원 고속 퓨리에 변환(Fast Fourier Transform) 스펙트럼을 이용해 위조된 데이터를 찾아낸다. 두 번째 단계에서는 눈 영상에 눈 깜박임이나 속눈썹의 홍채영역 침범, 홍채 영상이 부분적으로 잘렸을 경우 등의 시스템의 성능저하의 원인이 되는 부적절한 데이터를 찾아낸다. 111영의 1734개의 눈 영상을 대상으로 실험한 결과, 제안된 알고리즘의 성공률은 96.5%였고 이러한 전처리 과정을 통해서 전체적인 시스템의 정확률을 향상시킬 수 있다.

  • PDF

Computationally Efficient Rotor Fault Detection Algorithm Based on Motor Current Signature Analysis (효율적인 MCSA 기반 회전자 고장 검출 알고리즘)

  • Jeong, Chun-Ho;Song, Myung-Hyun;Kang, Eui-Sung;Kim, Kyung-Min
    • Proceedings of the KIEE Conference
    • /
    • 2002.07d
    • /
    • pp.2310-2312
    • /
    • 2002
  • 전류 신호에 대한 고속 퓨리에 변환(FFT)은 유도전동기의 고장 검출에 널리 사용되어 왔다. 본 논문에서는 고정자 전류 스펙트럼 중에서 회전자 고장에 의해서 많은 영향을 받는 주파수 성분들로 특징 벡터를 구성하고, 이를 단순한 산술 연산만으로 처리함으로써 회전자 고장을 검출한다. 제안한 방법에서는 고장의 유무를 검출하기 위해서 기준 벡터와 입력 고정자 전류 신호로부터 추출된 특징 벡터 간의 차이 신호만을 이용하기 때문에 신경망에 의한 고장 검출 알고리즘 등에 비해서 훨씬 적은 계산량 만으로도 모터의 고장을 효율적으로 검출할 수 있다.

  • PDF

Development and Performance Analysis of Radar Signal Processing for Autonomous Unmanned Ground Vehicle (자율주행 무인차량용 레이더 신호처리부 개발 및 성능 분석)

  • Shin, Seung-Yong;Choi, Jun-Hyeok;Park, Sang-Hyun;Yeom, Dong-Jin;Kim, Jeong-Ryul
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.16 no.4
    • /
    • pp.514-522
    • /
    • 2013
  • In this paper, we present signal processing procedure and carry out performance analysis of FMCW(Frequency Modulation Continuous Wave) radar for Autonomous Unmanned Vehicle(AUV). In order to detect range profile and velocity of the unknown target, we must implement two step FFT(Fast Fourier Transform) procedure. And the DBF(Digital Beam Forming) algorithm has to be performed to obtain the angle information of the unknown target. To verify the performance of manufactured autonomous unmanned ground vehicle FMCW radar, we use the data of the real corner reflecter target.

A Study on Gas Pressure Fluctuation Characteristics inside Pipe Line Passing Through a Snubber at Hydrogen Compressor (수소압축기 스너버 관로 내부의 맥동파 특성에 관한 연구)

  • Shim, K.J.;Yi, C.S.;Akbar, Wanda Ali;Chung, H.S.;Jeong, H.M.
    • Journal of Power System Engineering
    • /
    • v.10 no.4
    • /
    • pp.165-171
    • /
    • 2006
  • An experiment to observe reduction of pressure fluctuation in the compressing system utilizing snubber has done. The experiment measured pressure at inlet and outlet of snubber. It used an air compressor as a model of hydrogen one. Snubber with buffer and snubber without buffer were used to get comprehensive comparison between both of that snubber. An analysis by using Fast Fourier Transform (FFT) method was conducted to verify working pressure frequency. With this method pure signal of static pressure was filtered from noisy signal. The experiment was run for several speeds of piston movement. It was controlled by adjustable frequency regulator that controled rotation of actuator motor. This was connected to the piston-reciprocating compressor with V-belt. From result obtained, the fluctuation was increasing proportionally when frequency of driver motor was increased.

  • PDF

Fast Motion Artifact Correction Using l$_1$-norm (l$_1$-norm을 이용한 움직임 인공물의 고속 보정)

  • Zho, Sang-Young;Kim, Eung-Yeop;Kim, Dong-Hyun
    • Investigative Magnetic Resonance Imaging
    • /
    • v.13 no.1
    • /
    • pp.22-30
    • /
    • 2009
  • Purpose : Patient motion during magnetic resonance (MR) imaging is one of the major problems due to its long scan time. Entropy based post-processing motion correction techniques have been shown to correct motion artifact effectively. One of main limitations of these techniques however is its long processing time. In this study, we propose several methods to reduce this long processing time effectively. Materials and Methods : To reduce the long processing time, we used the separability property of two dimensional Fourier transform (2-D FT). Also, a computationally light metric (sum of all image pixel intensity) was used instead of the entropy criterion. Finally, partial Fourier reconstruction, in particular the projection onto convex set (POCS) method, was combined thereby reducing the size of the data which should be processed and corrected. Results : Time savings of each proposed method are presented with different data size of brain images. In vivo data were processed using the proposed method and showed similar image quality. The total processing time was reduced to 15% in two dimensional images and 30% in the three dimensional images. Conclusion : The proposed methods can be useful in reducing image motion artifacts when only post-processing motion correction algorithms are available. The proposed methods can also be combined with parallel imaging technique to further reduce the processing times.

  • PDF