• Smart Structures and Systems
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• 제14권3호
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• pp.445-468
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• 2014

The objective in this research is to determine the feasibility of using changes on the dynamic properties of a reinforced concrete (RC) structure to identify different levels of seismic induced damage. Damping ratio and natural frequency changes in a RC bridge column are analyzed using different signal processing techniques like Hilbert Transforms, Random Decrement and Wavelet Transforms. The data used in the analysis was recorded during a full-scale RC bridge column shake table test. The structure was subjected to ten earthquake excitations that induced different levels of inelastic demand on the column. In addition, low-intensity white noises were applied to the column in-between earthquakes. The results obtained show that the use of the damping ratio and natural frequency of vibration as damage indicators is arguable.

• 한국정보통신학회논문지
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• 제4권2호
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• pp.461-468
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• 2000

디지털 기술 발전에 따른 오디오 데이터의 증가는 여러 컴퓨터 응용에 사용되면서 데이터를 관리하고 사용하기 위해, 내용기반 질의와 유사성 검색과 같은 새로운 기능을 갖는 데이터베이스 시스템의 개발이 불가피하게 됐다. 내용 기반 질의를 위한 빠르고 정확한 검색은 이러한 응용 시스템들에 필요하다. 효율적인 내용기반 색인과 유사성 검색의 설계는 관련성 있는 데이터의 빠른 검색을 제공하기 위한 주된 요소이다. 본 논문에서는 소파(Wavelet) 변환을 이용한 한국 전통 음악 데이터베이스의 오디오 색인을 위한 방법을 제안한다. 또한 소파 변환을 이용해 오디오 데이터에 대한 색인의 가능성을 보인다.

• The Journal of the Acoustical Society of Korea
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• 제18권1E호
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• pp.13-19
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• 1999

This paper introduces an adaptive wavelet transform based on the lifting scheme, which is applied to signal denoising. The wavelet representation using orthogonal wavelet bases has received widespread attention. Recently the lifting scheme has been developed for the construction of biorthogonal wavelets in the spatial domain. Wavelet transforms are performed through three stages: the first stage or Lazy wavelet splits the data into two subsets, even and odd, the second stage calculates the wavelet coefficients (highpass) as the failure to interpolate or predict the odd set using the even, and the third stage updates the even set using neighboring odd points (wavelet coefficients) to compute the scaling function coefficients (lowpass). In this paper, we adaptively find some of the prediction coefficients for better representation of signals and this customizes wavelet transforms to provide an efficient framework for denoising. Special care has been given to the boundaries, where we design a set of different prediction coefficients to reduce the prediction error.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 봄 학술발표논문집 Vol.28 No.1 (B)
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• pp.151-153
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• 2001

Feature Simplification is an essential method for multiple representations of spatial features in GIS. However, spatial features re various, complex and a alrge size. Among spatial features which describe spatial information. linear feature is the msot common. Therefore, an efficient linear feature simplification method is most critical for spatial feature simplification in GIS. This paper propose an original method, by which the problem of linear feature simplification is mapped into the signal processing field. This method avoids conventional geometric computing in existing methods and exploits the advantageous properties of wavelet transform. Experimental results are presented to show that the proposed method outperforms the existing methods and achieves the time complexity of O(n), where n is the number of points of a linear feature. Furthermore, this method is not bound to two-dimension but can be extended to high-dimension space.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2052-2054
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• 2002

장비 플라즈마의 감시는 장비의 신뢰성과 생산성의 유지에 중요하다. 이산 웨이블릿 기술(Discrete Wavelet Transform)을 에칭 프로파일 표면의 이상(Anomaly)을 검출하는 데 응용하였다. 플라즈마 이상은 $SF_6$ 유량에 변화를 주면서 모의실험 되어졌다. 프로파일의 수직, 수평 그리고 수직과 수평부분이 합해진 부분에 대한 변환된 계수의 변화를 개별적, 그리고 총체적으로 평가하였다. 그 결과 각 부분에 대해 4번째의 계수가 가장 높은 민감도를 보였으며, 총체적인 평가에 있어서는 합해진 부분에 대한 민감도가 가장 높았다.

• ETRI Journal
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• 제40권1호
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• pp.133-145
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• 2018

Robustness, payload, and imperceptibility of audio watermarking algorithms are contradictory design issues with high-level security of the watermark. In this study, the major issue in achieving high payload along with adequate robustness against challenging signal-processing attacks is addressed. Moreover, a security code has been strategically used for secure transmission of data, providing tamper detection at the receiver end. The high watermark payload in this work has been achieved by using the complementary features of third-level detailed coefficients of discrete wavelet transform where the human auditory system is not sensitive to alterations in the audio signal. To counter the watermark loss under challenging attacks at high payload, Daubechies wavelets that have an orthogonal property and provide smoother frequencies have been used, which can protect the data from loss under signal-processing attacks. Experimental results indicate that the proposed algorithm has demonstrated adequate robustness against signal processing attacks at 4,884.1 bps. Among the evaluators, 87% have rated the proposed algorithm to be remarkable in terms of transparency.

• 대한전기학회논문지:전력기술부문A
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• 제49권12호
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• pp.608-613
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• 2000

This paper describes a fault location technique using wavelets in underground transmission power cable system. Estimation of fault location is performed using data smapled at two ends underground system. In the case of 50% fault of total underground transmission line, fault location is calculated using sampled single-end data in underground transmission line. Traveling wave is utilized in capturing the travel time of the transients along the monitored lines between the relay and the fault point. This traveling time information is provided by the wavelet. Simulation was performed using EMTP, ATP Draw and MATLAB. The results of fault location shown in this paper will be evaluated as an effective suggestion for fault location in real underground transmission line.

• 전기학회논문지P
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• 제57권4호
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• pp.377-382
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• 2008

For stator winding protection of AC generator, KCL(Kirchhoff's Current Law) is widely applied. Actually a CRDR(Current Ratio Differential Relay) based on DFT(Discrete Fourier Transform) has been used for protecting generator. It has been pointed out that defects can occur during the process of transforming a time domain signal into a frequency domain one which can lead to loss of time domain information. Wavelets techniques are proposed for the analysis of power system transients. This paper introduces an algorithm to choose a suitable Mother Wave1et for generator stator fault detection. For optimal selection, we analyzed db(Daubechies), sym(Symlets), and coif(Coiflects) of Mother Wavelet. And we compared with performance of the choice algorithm using detail coefficients energy and RMS(root mean square) error. It can be improved the reliability of the conventional DFT based CRDR. The feasibility and effectiveness of the proposed scheme is proved with simulation using collected data obtained from ATP (Alternative Transient Program) package.

• Smart Structures and Systems
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• 제22권6호
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• pp.711-725
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• 2018

Most of the practical engineering structures exhibit nonlinearity due to nonlinear dynamic characteristics of structural joints, nonlinear boundary conditions and nonlinear material properties. Hence, it is highly desirable to detect and characterize the nonlinearity present in the system in order to assess the true behaviour of the structural system. Further, these identified nonlinear features can be effectively used for damage diagnosis during structural health monitoring. In this paper, we focus on the detection of the nonlinearity present in the system by confining our discussion to only a few selective time-frequency analysis and multivariate analysis based techniques. Both damage induced nonlinearity and inherent structural nonlinearity in healthy systems are considered. The strengths and weakness of various techniques for nonlinear detection are investigated through numerically simulated two different classes of nonlinear problems. These numerical results are complemented with the experimental data to demonstrate its suitability to the practical problems.

• 한국인터넷방송통신학회논문지
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• 제13권4호
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• pp.179-191
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• 2013

영상처리에서 quincunx 격자를 사용하는 기법은 대표적인 비분리의 표본화 기법이다. 이 방법은 기존의 이차원 분리가능처리 기법보다 더 많은 다양한 방향성을 가지며 대역적 특성도 우수하다. 고밀도 이산 웨이브렛 변환은 N개의 입력 신호를 M개의 변환 계수들로 확장하는 변환이다(M>N). 이차원 처리에서 이 고밀도 이산 웨이브렛 변환의 이동불변의 장점은 표준 이산 웨이브렛 변환보다 더 우수하다. 그래서 이 변환은 다른 많은 웨이브렛보다 더 유용하게 사용될 수 있지만 표본화율이 높은 단점도 존재한다. 본 논문에서는 quincunx 표본화를 사용하는 고밀도 이산 웨이브렛 변환을 제안하였다. 이 방법은 고밀도 이산 웨이브렛과 비분리 처리의 특징을 유지하고 조합하는 방법이다. 제안된 방법은 영상처리 응용분야에서 좋은 성능을 갖는다.