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황기환,고대식,전계석 慶熙大學校 材料科學技術硏究所 1992 材料科學技術硏究論集 Vol.5 No.-
In this paper, using the spectra and the reflection coefficient of surface acoustic wave:SAW, the surface breaking crack-depth is estimated by computer simulation and the experiment. In order to perform this experiment, two type shaped flows half-penny and rectangular of line-crack have been made in the surface of aluminium. Measuring results, for half-penny type, the reflection coefficient have been in proportion to the surface breaking crack-depth. When the spectrum analyzer was used, the spectra analysis method for line crack of rectangular type was measured the average deviation 8.7% to the surface breaking crack-depth.
Scanning Tomographic Acoustic Microscope 시스템의 신호검출 연구
전계석,고대식,황기환 慶熙大學校 레이저 工學硏究所 1995 레이저공학 Vol.6 No.-
In the process, that develop the system for the ultrasonic tomographic image with high resolution, called scanning tomographic acoustic microscope(STAM), this paper is presented to the constitution and operation for the data acquisition with high resolution. The principle of BFP(back-and-forth propagation) associated with STAM image reconstruction are discussion. The transfer function to the knife-edge detector is analysed through simulation. In these results, using the knife-edge demodulation technique is shown that can be acquired the surface displacement data less than laser beam of Gaussian intencity profile.