• Title, Summary, Keyword: Stationary wavelet transform (SWT)

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SWT (Stationary Wavelet Transform)을 이용한 영상 잡음 제거

  • Yu, Hye-Rim;Jo, Hyeon-Suk;Lee, Hyeong;Lee, In-Jeong
    • Proceedings of the Korea Society of Information Technology Applications Conference
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    • pp.9-28
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    • 2007
  • It is well known that wavelet transform is a signal processing technique which can display the signals on in both time and frequency domain. In this paper, we proposed a new approach based on stationary wavelet transform to provide an enhanced approach for eliminating noise. A 'stationary wavelet transform', where the coefficient sequences are not decimated at each stage, is described. The testing result on sample iris images has shown an enhanced image quality and also show that it has a superior performance than traditional discrete wavelet transform.

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Development of Fault Location Method Using SWT and Travelling Wave on Underground Power Cable Systems (SWT와 진행파를 이용한 지중송전계통 고장점 추정 기법 개발)

  • Jung, Chae-Kyun;Lee, Jong-Beom
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.2
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    • pp.184-190
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    • 2008
  • The fault location algorithm based on stationary wavelet transform was developed to locate the fault point more accurately. The stationary wavelet transform(SWT) was introduced instead of conventional discrete wavelet transform(DWT) because SWT has redundancy properties which is more useful in noise signal processing. In previous paper, noise cancellation technique based on the correlation of wavelet coefficients at multi-scales was introduced, and the efficiency was also proved in full. In this paper, fault section discrimination and fault location algorithm using noise cancellation technique were tested by ATP simulation on real power cable systems. From these results, the fault can be located even in very difficult and complicated situations such as different inception angle and fault resistance.

A Study on the Comparison of Denoising Performance of Stationary Wavelet Transform for Discharge Signal Data in Cast-resin Transformer (SWT(Stationary Wavelet Transform)를 이용한 몰드변압기 방전 측정신호의 디노이징 특성 연구)

  • Choi, Myeong-Il;Kim, Jae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.3
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    • pp.84-90
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    • 2014
  • The partial discharge of Cast-resin Transformer has a difficulty to be analyzed, because it is an abnormal condition signal of which stochastic characteristics varies with time variance. In this study, background noise coming from the outside of the cast-resin transformers through ground wire can be removed and only a discharge signal of which defects are simulated can be obtained, using the wavelet transform method, which is a time-frequency domain analysis technique. As a result, it was confirmed that de-noising using the SWT technique is the best efficient among three methods of the wavelet transform techniques.

SWT -based Wavelet Filter Application for De-noising of Remotely Sensed Imageries

  • Yoo Hee-Young;Lee Kiwon;Kwon Byung-Doo
    • Proceedings of the KSRS Conference
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    • pp.505-508
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    • 2005
  • Wavelet scheme can be applied to the various remote sensing problems: conventional multi-resolution image analysis, compression of large image sets, fusion of heterogeneous sensor image and segmentation of features. In this study, we attempted wavelet-based filtering and its analysis. Traditionally, statistical methods and adaptive filter are used to manipulate noises in the image processing procedure. While we tried to filter random noise from optical image and radar image using Discrete Wavelet Transform (DW1) and Stationary Wavelet Transform (SW1) and compared with existing methods such as median filter and adaptive filter. In result, SWT preserved boundaries and reduced noises most effectively. If appropriate thresholds are used, wavelet filtering will be applied to detect road boundaries, buildings, cars and other complex features from high-resolution imagery in an urban environment as well as noise filtering

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Fault Location Using Noise Cancellation Technique on Underground Power Cable Systems (노이지 제거기법을 이용한 지중송전계통 고장점 추정)

  • Jung, Chae-Kyun;Lee, Jong-Beom
    • Proceedings of the KIEE Conference
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    • pp.440-441
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    • 2006
  • The fault location algorithm based on wavelet transform was developed to locate the fault more accuracy after the operation of relay. The stationary wavelet transform(SWT) was introduced instead of conventional discrete wavelet transform(DWT) because SWT has redundancy properties which is more useful in noise signal processing. The algorithm was based on the correlation of wavelet coefficients at multi-scales. Fault location algorithm was tested by simulation on real power cable system. From these results, the fault can be located even in very difficult situations, such as at different inception angle and fault resistance.

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웨이브렛 필터를 이용한 위성영상에서의 잡음 제거

  • Ryu, Hui-Yeong;Lee, Gi-Won;Gwon, Byeong-Du
    • 한국지구과학회:학술대회논문집
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    • pp.400-407
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    • 2005
  • 웨이브렛 변환(Wavelet Transform)은 시간영역과 주파수영역에서 동시에 분석이 가능하고 불연속적인 자료를 분석하는데 유리하기 때문에 그동안 영상을 처리하고 분석하는데 널리 이용되어 왔다. Discrete Wavelet Transform(DWT)는 주어진 영상에서 특성 정보는 유지하면서 다른 여러 종류의 계수로 분해 할 수 있게 해주기 때문에, 계수에 임계치를 적용해 고주파 성분을 제거하면 잡음을 줄일 수 있다. Stationary Wavelet Transform(SWT)는 DWT에서 다운샘플링에 의해 발생하는 문제점을 해결하기 위한 변환방법으로 잡음제거에 DWT보다 효과적이라고 알려져 있다. 이 연구에서는 DWT와 SWT에 의한 필터링을 광학영상과 레이더 영상에 적용하여 보고, 기존의 필터링 기법과 그 결과를 비교하였다. 그 결과 SWT에 의한 방법이 경계성분은 보존하면서 잡음을 가장 효과적으로 줄일 수 있었다.

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A Study on the Fault Location Using Multiscale Correlation in Underground Power Cable Systems (Multiscale Correlation을 이용한 지중송전계통 고장점 추정에 관한 연구)

  • Jung Chae Kyun;Lee Jong Beom;Kang Ji Won
    • Proceedings of the KIEE Conference
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    • pp.557-559
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    • 2004
  • The study of applying wavelet transform in power cable system fault location has been recognized by many researchers and investigated. For performance of fault location, the fault generated transients can be captured at one end of the cable or both ends. Between two approaches, single-ended approach is less expensive and more reliable as it doesn't need communication link between the ends of the cable. So, we performs the approach based on the one. In this paper, we are going to introduce a new algorithm to discriminate the transient and the reflected signal using wavelet coefficient. For wavelet transform, the stationary wavelet transform(SWT) is applied instead of conventional DWT because SWT has redundancy properties which is more useful in noisy signal processing.

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Abnormal Detection of CTLS Aircraft Wing Structure using SWT (SWT를 이용한 CTLS항공기 날개 구조물 이상탐지)

  • Shin, Hyun-Sung;Hong, Gyo-Young
    • The Journal of Advanced Navigation Technology
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    • v.22 no.5
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    • pp.359-366
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    • 2018
  • In this paper, the noise is removed by using CTLS aircraft installed FBG sensor inside the aircraft wing. We suggest a normal wavelet transform scheme with motion - invariant characteristics for noise reduction. In the case of installing FBG sensors inside the composite material as in CTLS, large and small empty spaces and parts or sections are generated between the adhesive layers, and a signal splitting problem occurs. FBG sensor is not affected by noise. but eletromagnetic, light source, light detector and signal processing device are influeced by noise because these are eletronic components what affected by eletromagnetic wave. because of this, errors are occured. Experimental results show that the noise can be removed using normal wavelet transform and more accurate data detection is possible.

An Efficient Selective Method for Audio Watermarking Against De-synchronization Attacks

  • Mushgil, Baydaa Mohammad;Adnan, Wan Azizun Wan;Al-hadad, Syed Abdul-Rahman;Ahmad, Sharifah Mumtazah Syed
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.476-484
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    • 2018
  • The high capacity audio watermarking algorithms are facing a main challenge in satisfying the robustness against attacks especially on de-synchronization attacks. In this paper, a robust and a high capacity algorithm is proposed using segment selection, Stationary Wavelet Transform (SWT) and the Quantization Index Modulation (QIM) techniques along with new synchronization mechanism. The proposed algorithm provides enhanced trade-off between robustness, imperceptibility, and capacity. The achieved watermarking improves the reliability of the available watermarking methods and shows high robustness towards signal processing (manipulating) attacks especially the de-synchronization attacks such as cropping, jittering, and zero inserting attacks. For imperceptibility evaluation, high signal to noise ratio values of above 22 dB has been achieved. Also subjective test with volunteer listeners shows that the proposed method has high imperceptibility with Subjective Difference Grade (SDG) of 4.76. Meanwhile, high rational capacity up to 176.4 bps is also achieved.

Wavelet based multi-step filtering method for bridge health monitoring using GPS and accelerometer

  • Yi, Ting-Hua;Li, Hong-Nan;Gu, Ming
    • Smart Structures and Systems
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    • v.11 no.4
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    • pp.331-348
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    • 2013
  • Effective monitoring, reliable data analysis, and rational data interpretations are challenges for engineers who are specialized in bridge health monitoring. This paper demonstrates how to use the Global Positioning System (GPS) and accelerometer data to accurately extract static and quasi-static displacements of the bridge induced by ambient effects. To eliminate the disadvantages of the two separate units, based on the characteristics of the bias terms derived from the GPS and accelerometer respectively, a wavelet based multi-step filtering method by combining the merits of the continuous wavelet transform (CWT) with the discrete stationary wavelet transform (SWT) is proposed so as to address the GPS deformation monitoring application more efficiently. The field measurements are carried out on an existing suspension bridge under the normal operation without any traffic interference. Experimental results showed that the frequencies and absolute displacements of the bridge can be accurate extracted by the proposed method. The integration of GPS and accelerometer can be used as a reliable tool to characterize the dynamic behavior of large structures such as suspension bridges undergoing environmental loads.