• Title/Summary/Keyword: 초음파 절대변위

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Measurement of Absolute Displacement-Amplitude of Ultrasonic Wave Using Piezo-Electric Detection Method (압전형 수신 기법을 이용한 초음파 절대변위진폭 측정)

  • Park, Seong-Hyun;Kim, Jongbeom;Jhang, Kyung-Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.37 no.1
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    • pp.7-12
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    • 2017
  • A nonlinear ultrasonic parameter is defined by the ratio of displacement amplitude of the fundamental frequency component to that of the second-order harmonic frequency component. In this study, the ultrasonic displacement amplitude of an SUS316 specimen was measured via a piezo-electric-based method to identify the validity of piezo-electric detection method. For comparison, the ultrasonic displacement was also determined via a laser-based Fabry-Pérot interferometer. The experimental results for both measurements were in good agreement. Additionally, the stability of the repeated test results from the piezo-electric method exceeded that of the laser-interferometric method. This result indicated that the piezo-electric detection method can be utilized to measure a nonlinear ultrasonic parameter due to its excellent stability although it involves a complicated process.

A Study on the 3-Dimensional Implementation of Computer-Aid Management of Stereo Images (입체 화상의 3차원 전산모사기 구현에 관한 연구)

  • Lee, Joong;Yoon, Do-Young
    • Korean Chemical Engineering Research
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    • v.47 no.2
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    • pp.179-184
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    • 2009
  • Recent evolution of computer technology enhances the effectiveness of CFD(Computational Fluid Dynamics) analysis for the 3-dimensional complex transport phenomena including turbulent flows. Cheaper and easier than laser and ultra-sonic methods, the windows simulator name by CAMSI(Computer-Aided Management of Stereo Images) has been developed in order to implement the 3-dimensional image using a disparity histogram extracted from left and right stereo images. In our program using the area-based method, the matching pixel finding methods consist of SSD(Sum of Squared Distance), SAD(Sum of Absolute Distance), NCC(Normalized Correlation Coefficient) and MPC(Matching Pixel Count). On performing the program, stereo images on different window sizes for various matching pixel finding methods are compared reasonably. When the image has a small noise, SSD on small window size is more effective. Whereas there is much noise, NCC or MPC is more effective than SSD. CAMSI from the present study will be much helpful to implement the complex objects and to analyze 3-dimensional CFD around them.