• Title/Summary/Keyword: Wavelet transform

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Analysis of Hydrologic Time Series Using Wavelet Transform (Wavelet Transform을 이용한 수문시계열 분석)

  • Kwon, Hyun-Han;Moon, Young-Il
    • Journal of Korea Water Resources Association
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    • v.38 no.6 s.155
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    • pp.439-448
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    • 2005
  • This paper introduces the wavelet transform that was improved by the fourier transform to assess periodicities and trends, we assessed propriety with examples of two monthly precipitation data, annual precipitation, SOI index and SST index. The wavelet transform can effectively assess the power spectrum corresponding to frequency as maintaining chronological characteristics. The results of the analysis using the wavelet transform showed that the monthly precipitation have the strongest power spectrum near that of 1 year, and the annual precipitation represent the dominated spectrum in the band of 2-8 years. Also, the SOI index and SST index indicate the strongest power spectrum in the band of 2-8 years.

Denoising of Speech Signal Using Wavelet Transform (웨이브렛 변환을 이용한 음성신호의 잡음제거)

  • 한미경;배건성
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.5
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    • pp.27-34
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    • 2000
  • This paper deals with speech enhancement methods using the wavelet transform. A cycle-spinning scheme and undecimated wavelet transform are used for denoising of speech signals, and then their results are compared with that of the conventional wavelet transform. We apply soft-thresholding technique for removing additive background noise from noisy speech. The symlets 8-tap wavelet and pyramid algorithm are used for the wavelet transform. Performance assessments based on average SNR, cepstral distance and informal subjective listening test are carried out. Experimental results demonstrate that both cycle-spinning denoising(CSD) method and undecimated wavelet denoising(CWD) method outperform conventional wavelet denoising(UWD) method in objective performance measure as welt as subjective listening test. The two methods also show less "clicks" that usually appears in the neighborhood of signal discontinuities.

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A Study on the Application of Wavelet Transform to Faults Current Discrimination (Wavelet 변환을 이용한 고장전류의 판별에 관한 연구)

  • 조현우;정종원;윤기영;김태우;이준탁
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2002.05a
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    • pp.213-217
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    • 2002
  • Recently the subject of "wavelet analysis" has be drawn by both mathematical and engineering application fields such as Signal Processing, Compression/Decomposition, Wavelet-Neural Network, Statistics and etc. Even though its similar to courier analysis, wavelet is a versatile tool with much mathematical content and great potential for applications. Especially, wavelet transform uses localizable various mother wavelet functions in time-frequency domain. Therefore, wavelet transform has good time-analysis ability for high frequency component, and has good frequency-analysis ability for low frequency component. Using the discriminative ability is more easy method than other conventional techniques. In this paper, Morlet wavelet transform was applied to discriminate the kind of line fault by acquired data from real power transformation network. The experimental result presented that Morlet wavelet transform is easier, and more useful method than the FFW (Fast courier Transform).ransform).

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Analysis of Ultrasonic signal in GIS using Wavelet transform (Wavelet transform을 이용한 GIS내 초음파 신호 분석)

  • Lee, Dong-Zoon;Kwak, Hee-Ro;Park, Jung-Shin;Kim, Du-Suk
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1918-1920
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    • 2000
  • In this paper, acoustic signals in GIS were analyzed by using wavelet transform and FFT to distinguish sound source caused by collision of particles and partial discharges. As a result, the analysis using wavelet transform was more accurate than that using FFT. Therefore, wavelet transform was useful technique to analyze the acoustic signals in GIS.

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Damage Detection of Frame Structure Using Wavelet Transform (골조의 손상부위 추정에 웨이블렛 변환의 이용)

  • 박종열;이의택;박진호;박형기
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2002.09a
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    • pp.173-180
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    • 2002
  • This paper presents a signal processing procedure to detect damage locations of frame structures by using continuous wavelet transform. Morlet wavelet is used as a mother wavelet in wavelet transform. Wavelet transform has the characteristics that allows the use of long time intervals at more precise low-frequency information, and shorter regions at high-frequency information. By this wavelet transform characteristics, Morlet wavelet may be used to identify the locations of damages in the structures. The numerical case studies show that this method can be applied to detect the damage location under a controlled sweeping load.

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Hierarchical classification of Fingerprints using Discrete Wavelet Transform (이산 웨이블릿 변환을 이용한 지문의 계층적 분류)

  • Kwon, Yong-Ho;Lee, Jung-Moon
    • Journal of Industrial Technology
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    • v.19
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    • pp.403-408
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    • 1999
  • An efficient method is developed for classifying fingerprint data based on 2-D discrete wavelet transform. Fingerprint data is first converted to a binary image. Then a multi-level 2-D wavelet transform is performed. Vertical and horizontal subbands of the transformed data show typical energy distribution patterns relevant to the fingerprint categories. The proposed method with moderate level of wavelet transform is successful in classifying fingerprints into 5 different types. Finer classification is possible by higher frequency subbands and closer analysis of energy distribution.

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Architecture Design of 3D-Wavelet Transform encoder based on Lifting Scheme (리프팅 기반의 3차원 웨이블릿 변환 인코더의 아키텍쳐 설계)

  • 조덕은;송낙운
    • Proceedings of the IEEK Conference
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    • 2003.11a
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    • pp.409-412
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    • 2003
  • In this paper, the encoder architecture of 3-D wavelet transform based on lifting scheme is designed. Architecture, here, 3 level wavelet transform for spatial decomposition and 2 level wavelet transform for temporal decomposition is adopted with efficient computation.

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Damping Identification Analysis of Membrane Structures under the Wind Load by Wavelet Transform

  • Han, Sang-Eul;Hou, Xiao-Wu
    • Architectural research
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    • v.11 no.1
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    • pp.7-14
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    • 2009
  • In this paper, we take advantage of Wavelet Transform to identify damping ratios of membrane structures under wind action. Due to the lightweight and flexibility of membrane structures, they are very sensitive to the wind load, and show a type of fluid-structure interaction phenomenon simultaneously. In this study, we firstly obtain the responses of an air-supported membrane structure by ADINA with the consideration of this characteristic, and then conduct Wavelet Transform on these responses. Based on the Wavelet Transform, damping ratios could be obtained from the slope of Wavelet Transform in a semi-logarithmic scale at a certain dilation coefficient. According to this principle, damping ratios could eventually be obtained. There are two numerical examples in this study. The first one is a simulated signal, which is used to verify the accuracy of the Wavelet Transform method. The second one is an air-supported membrane structure under wind action, damping ratios obtained from this method is about 0.05~0.09. The Wavelet Transform method could be regarded as a very good method for the the damping analysis, especially for the large spatial structures whose natural frequencies are closely spaced.

Condition Monitoring in Gear System Using Spike Wavelet Transform (스파이크 웨이블렛 변환을 이용한 기어 시스템의 건전성 감시)

  • 이상권;심장선
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.5
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    • pp.21-27
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    • 2001
  • Impulsive sound and vibration signals in gear system are often associated with their faults. Thus these impulsive sound and vibration signals can be used as indicators in condition monitoring of gear system. The traditional continuous wavelet transform has been used for detection of impulsive signals. However, it is often difficult for the continuous wavelet transform to identify spikes at high frequency and meshing frequencies at low frequency simultaneously since the continuous wavelet transform is to apply the linear scaling (a-dilation) to the mother wavelet. In this paper, the spike wavelet transform is developed to extract these impulsive sound and vibration signals. Since the spike wavelet transform is to apply the non-linear scaling, it has better time resolution at high frequency and frequency resolution at low frequency than that of the continuous wavelet transform respectively. The spike wavelet transform can be, therefore, used to detect fault position clearly without the loss of information for the damage of a gear system. The spike wavelet transform is successfully is applied to detection of the gear fault with tip breakage.

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Detection of Chatter using Wavelet Transform (웨이브렛 변환을 이용한 채터 검출)

  • Oh, Sang-Lok;Chin, Do-Hum;Yoon, Moon-Chul;Ryoo, In-Ill;Ha, Man-Kyung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.3 no.2
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    • pp.32-38
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    • 2004
  • The chatter behaviour in endmilling is a complex and nonlinear phenomenon, so it is very difficult to detect and diagnose this chatter phenomenon, This paper presents new method for the detection of chatter in endmilling operation based on the wavelet transform. In this paper, the fundamental property of the wavelet transform is reviewed by comparing the spectrum of other algorithm such as FFT. This result using wavelet transform shows the possibiling of the chatter detection in endmilling operation.

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