디포커스를 이용한 고체내부 음향영상의 해상도 개선에 관한 연구

문건 濟州大學校 産業技術硏究所 1999 산업기술연구소논문집 Vol.10 No.1

The most difficult problem has to be solved in acoustic image detection existing in solid-interior is to reduce the strong surface signals. In order to solve this problem, this paper proposed the new technique enhancing the resolution of acoustic images by applying the defocus method which can reduce the reflected surface signals efficiently. The key point of this technique is to find the optimum defocus distance between acoustic transducer and sample object. Using the packaged LSI as the experimental sample, I detected the subsurface IC images applying the proposed defocus technique. The experimental results showed the better resolution and confirmed this technique can be used usefully in acoustic none destructive test.

음향현미경의 V(z)곡선을 이용한 재료의 특성에 관한 연구

문건,고대식,전계석,Moon, G.,Ko, D.S.,Jun, K.S. 한국음향학회 1988 韓國音響學會誌 Vol.7 No.2

본 논문에서는 음향현미경의 V(z)곡선을 해석하고 실험결과와 비교 고찰하였으며 V(z)곡선과 재료의 탄성 특성사이의 관계를 연구분석하였다. V(z)곡선의 이론적인 해석은 angular spectrum과 ray optics 이론을 사용하였고 실험은 동작주파수가 3MHz인 음향현미경을 구성하여 행하였다. 실험결과 V(z)곡선은 재료마다 고유의 형태를 나타내며 V(z) 곡선에서 극대치 사이의 간격은 재료에서 Rayleigh 파의 음향속도를 산출하는 데 이용될 수 있음을 보였다. In this paper, V(z) curve has been analyzed theoretically and compared with the experimental result, and the relation between the V(z) curve and the material characteristic has been studied. Angular spectrum and ray optics theory have been used for theoretical analysis and the acoustic microscope operating at a center frequency of 3 MHz has been used for experiment. In experiment, it has been shown that each material has a V(z) curve of a unique form and the interval of dips appearing in the V(z) curves have been used to determine the Rayleigh wave velocity.

음향횡파를 이용한 고체내부의 영상검출 개선에 관한 연구

문건,Moon, Gun 한국통신학회 1991 韓國通信學會論文誌 Vol.16 No.12

본 연구에서는 음향파의 입사각을 횡파임계각도 이상으로 하여 횡파를 발생시키고 이를 이용하여 종래방식보다 고체 내부에 존재하는 미소결함의 검출한계를 개선시키는 방법을 연구분석하였다. 실험을 위하여 중심주파수3MHz인 반사형 음향현미경 시스템을 구성하였고 서로 다른 깊이에 임의의 결함을 갖는 시료를 제작하였으며 defocus 깊이를 변화시키면서 실험하였다. 실험결과 고체내부 Rayleigh파장의 3배정도 깊이에 존재하는 1mm 크기의 결함을 검출할 수 있었다.

디포커스를 이용한 고체내부 음향영상의 해상도 개선에 관한 연구

문건 濟州大學校工科大學産業技術硏究所 1999 尖端技術硏究所論文集 Vol.10 No.1

The most difficult problem has to be solved in acoustic image detection existing in solid-interior is to reduce the strong surface signals. In order to solve this problem, this paper proposed the new technique enhancing the resolution of acoustic images by applying the defocus method which can reduce the reflected surface signals efficiently. The key point of this technique is to find the optimum defocus distance between acoustic transducer and sample object. Using the packaged LSI as the experimental sample, I detected the subsurface IC images applying the proposed defocus technique. The experimental results showed the better resolution and confirmed this technique can by used usefully in acoustic none destructive test.

집속음향파를 이용한 고체특성 판별에 관한 연구

문건,Moon, Gun 한국통신학회 1993 韓國通信學會論文誌 Vol.18 No.1

본 연구에서는 3MHZ의 접속 음향변환자를 사용하여서 고체 샘플에서 반사되어 오는 음향파를 검출하는 시스템을 구성하였고, 이를 이용하여 음향 변환자의 촛점위치와 고체표면과의 거리(Z)에 따른 음향 반사신호의 특성곡선 V(Z)을 검출하였다. 여러가지 고체재료의 V(Z) 특성곡선을 실험에의해 검출한 결과 고체에따라 그들 고유의 V(Z)특성곡선 모양을 나타내고 있음을 보여 주었다. 본 연구에서는 V(Z)곡선을 분석하면 고체특성을 판별할 수 있음을 제시하였다. On this study. Constructed the system detecting the reflective acoustic waves from the solid-samples using the 3MHZ focused-acoustic transducer and detected the V(Z) charateristics curves varied by the distance between the focusing position and the solid surface. The results of the experimental detection to various solid materials showed that the materials have their own unique shape of V(Z) curves. This paper suggested the possibility distinguishing the solid characteristics by analysing the V (Z) curves.

비파괴검사에 사용되는 음향현미경 렌즈의 설계와 분해능 해석

文建 군산대학교 1986 群山水産專門大學 硏究報告 Vol.20 No.3

It has been necessary during the course of research to develop several new types of transducer for nondestructive testing. One of the best transducers is the scanning acoustic microscope using the acoustic lens. Acoustic microscope can display small opaque material or internal defects of solids. In this paper, I showed design method of acoustic lens and analyzed spherical aberration and diffraction effect which are very important factors in resolution of acoustic microscope.

Wiener 필터를 이용한 물체표면 음향영상의 품질향상

문건 濟州大學校工科大學産業技術硏究所 1996 尖端技術硏究所論文集 Vol.7 No.1

중심주파수 3Mhz의 구면형 음향변환자를 설계하여 음향영상 시스템을 구성하여서 100원 짜리 동전의 음향영상 데이터를 수신한 후에 Wiener 필터 방식을 적용하여 음향영상신호를 개선하여 잡음이 제거된 영상을 구현하였다. 여기서 잡음을 제거하기 위하여 사용한 Wiener 필터방식은 신호와 임펼스 응답신호를 컨벌루숀하여서 잡음신호와는 구별된 수 있도록 하는 방식으로 2차원 영상에 적용한 경우 매우 좋은 결과를 얻을 수 있었다. 음향신호에서 많이 나타나는 영상신호 이외의 간섭잡음 및 충격성 잡음을 제거하는 우수성을 구성한 시스템을 이용한 실험결과로서 확인하였다. 그러나 3차원 적인 영상검출 특히 고체내부의 결함검출을 위한 비파괴 검사에서 발생하는 복잡한 간섭잡음에 대하여 Wiener 필터방식을 적용하는 방안을 연구하여 더 발전해 나아가야 할 것이다. Although acoustic image is an effective and powerful method for image of materials, the technique is limited by the blurring and distortion introduced by limits of the image system. Therefore, some method of image-signal processing is essential to improve and restore the acquired images and to provide a qualitative improvement of the image evaluation process. The Wiener filtering method is one such proven method of image-signal restoration. This paper discusses the implementation of a Wiener filter in two dimensional application for image processing. Theoretical aspects of Wiener filter are briefly discussed. Results of processing acoustic signal and images acquired from coin samples are provided, also compared the methods and results between non-using Wiener filter and using Wiener filter.

마이크로 프로세서를 이용한 CW송신 자동화 시스템

文建,金圭煥 군산대학교 1985 群山水産專門大學 硏究報告 Vol.19 No.3

In this paper, we described as to automatization on CW-transmission being mainly used in the maritime communication nowadays. The experimental results by using the edited programs and the developed interface hardware showed the excellent effectivity and accuracy. The CPU-6502 micro-processor was used in this system. It was proved that CW can be transmitted with good stability on the high speed more than 500CPM (characters per minute). We found that this system is very useful and effective and also save the the educational time of the students who are training the CW-morse code on keying and receiving skill.

음향파를 이용한 금속 부식상태 판별에 관한 연구

문건 제주대학교 산업기술연구소 1999 尖端技術硏究所論文集 Vol.10 No.2

On this study, constructed the reflective acoustic detecting system using 15MHz acoustic transducer. The most difficult problem in metal substance is to discriminate the corrosion state using none destructive method. As the test samples, the six 100 won coins which are issued on the different years are used. The experimental results showed the distinct difference among the coin's acoustic signals accorded to its issued years. I catches the common regulation in acquisited acoustic signals and convinced this technique to be very useful in corrosion discrimination of the metal substances on none destructive testing.

지연시간 변별에 의한 음향영상 분리개선에 관한 연구

문건 濟州大學校 産業技術硏究所 1998 산업기술연구소논문집 Vol.9 No.2

The most difficult problem to be solved in the None-Destructive-Test is the separation of the correlated acoustic images caused by existing more than two images on the same axis. Though various techniques are proposed but satisfactory results are not yet come out. In this paper, I proposed the new technique enhancing the resolution of acoustic images by applying the time-delay signal aquisition method. By using the 500 won coin as the experimental sample, 1 detected and separated the backside image which is correlated with the front surface image by applying proposed technique. I used the variable time delayed pulse to distinguish the complex acoustic signals. The experimental results confirmed the better resolution compare with data thresholding techniques in separating the images.