Journal of Korea Multimedia Society (한국멀티미디어학회논문지)

Korea Multimedia Society (한국멀티미디어학회)
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Colorization of C-Scan Ultrasonic Image and Automatic Evaluation Algorithm of Welding Quality

C-Scan 초음파 영상 컬러화 및 용접 품질 자동 평가 시스템

  • Kim, Tae-Kyu (School of Electronics Engineering, Kyungpook National University) ;
  • Kwon, Seong-Geun (Department of Electronics Engineering, KyungIl University)
  • Received : 2018.09.13
  • Accepted : 2018.10.23
  • Published : 2018.11.30
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Abstract

The NDT using ultrasonic is largely divided into A-Scan and C-Scan methods. Since A-Scan method is subject to subjective judgement by trained personnel, C-Scan method has been introduced, which presents the weld area in two dimensions by placing the transducers two dimensionally used in the A-Scan method. Therefore, it is necessary to develop equipment that can provide weld quality without the help of a welding expert and the presentation of effective C-Scan images. Thus, in this paper, the algorithms that express a low resolution 2-dimensional gray image formed by C-Scan method as a high-resolution color C-Scan image and automatically determine the weld quality from the generated C-Scan color image. The high resolution color C-Scan images proposed in this paper allow the exact shape of the weld point to be expressed, and an objective algorithm to use this image to automatically determine weld quality.

Keywords

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Fig. 4. Gray level matching according to echo signal reflected at the welding point.

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Fig. 5. Proposed block diagram consisting of C-Scan image colorization and automatic welding quality evaluation algorithm.

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Fig. 6. C-Scan image (a) with improved brightness and spatial resolution, (b) filtered by Gaussian filter with variance of 8, (c) by closing operation of the morphology and (d) by color mapping.

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Fig. 7. C-Scan image of (a) binarization of closing image, (b) edge detection, (c) circumscribed circle, and (d) in-scribed circle of welding point.

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Fig. 8. Circumscribed circle and inscribed circle ma-tched on (a) color C-Scan image and (b) weld-ing image.

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Fig. 9. Structure of 2D ultrasonic transducer with 64 channel.

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Fig. 1. (a) Measuring using ultrasonic probe and (b) echo signal presentation in A-Scan mode.

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Fig. 2. (a) Measuring using ultrasonic probe and (b) echo signal presentation in C-Scan mode.

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Fig. 3. (a) Front image and (b) both side expressed im-ageby S-Scan probe

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Fig. 10. (a) C scan color images and (b) welding images found to be“defective.”

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Fig. 11. (a) C scan color images and (b) welding images found to be“good.”

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Fig. 12. (a) C scan color images and (b) welding images found to be“very good.”

References

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