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홍진철(Hong, Jin-Chul),선경호(Sun, Kyung-Ho),김윤영(Kim, Yoon-Young) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.4
For successful guided-wave damage inspection, the appropriate signal processing of measured wave signals is very important. The objective of this paper is to introduce an efficient signal processing technique especially suitable for the guided-waves used for damage detection. The key idea of this technique is to model guided-waves by chirp functions of special form considering the dispersion phenomenon. To determine the parameter of the chirp functions simulating guided-waves, the matching pursuit algorithm is employed. The damage information in waveguides can be extracted by pulse-characterizing parameters. The effectiveness of present method is checked with the guided wave-based damage inspection.
유도 초음파 신호 분석을 위한 적응 단시간 푸리에 변환
홍진철(Hong, Jin-Chul),선경호(Sun, Kyung-Ho),김윤영(Kim, Yoon-Young) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.3
Although time-frequency analysis is useful for dispersive wave analysis, conventional methods such as the short-time Fourier transform do not take the dispersion phenomenon into consideration in the tiling of the time-frequency domain. The objective of this paper is to develop an adaptive time-frequency analysis method whose time-frequency tiling is determined with the consideration of signal dispersion characteristics. To achieve the adaptive time-frequency tiling, each of time-frequency atoms is rotated in the time-frequency plane depending on the local wave dispersion. To carry out this adaptive time-frequency transform, dispersion characteristics hidden in a signal are first estimated by an iterative scheme. To examine the effectiveness of the present method, the flexural wave signals measured in a plate were analyzed.