• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.556-559
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• 2008

용접부 내에 존재하는 결함의 형태, 위치, 크기 등의 정보를 정량적으로 파악하기 위하여 초음파 탐상 검사가 많이 활용되는데, 최근 들어 용접부의 결함 탐상을 위해, 검사과정을 기계적 스캐너로 자동화한 자동 초음파 탐상 시스템이 많은 산업분야에서 활용되고 있고, 특히 배관 용접부의 건전성 평가를 위한 비 파괴안전진단에서 그 활용 폭이 커지고 있다. 배관 용접부 건전성 제고를 위해 본 연구를 통해 용접부 결함 영상화 프로그램을 구현하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권6호
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• pp.456-461
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• 1999

In this study, the characteristics of Ultrasonic Transducer fabricated with PZT-Polymer 1-3 type piezoelectric ceramic/polymer composite are investigated. 3-D underwater object restoration using the self-made ultrasonic transducer and modified SCL(Simple Competitive Learning) neural network was presented. The ultrasonic transducer was satisfied with the required condition of commerical ultrasonic transducer in underwater. The modified SCL neural network using the acquired object data $16\times16$ low resolution image was used for object restoration of $32\times32$ high resolution image. The experimental results have shown that the ultrasonic transducer fabricated with PZT-Polymer 1-3 type piezoelectric ceramic/polymer composite could be applied for SONAR system.

• 한국재료학회지
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• 제13권10호
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• pp.651-657
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• 2003

Ultrasonic microscope has been used to detect the defects on surface or inner solid. Conventionally, it has used at a single operating frequency. The resolution and quality of the measured images are determined by a characteristic of the transducer of the ultrasonic microscope. The conventional ultrasonic microscope has been used envelope detector to detect the amplitude of reflected signal, but the changes in amplitude is not sensitive enough for specimen with microstructure that in phase. In this paper, we have studied multi-frequency depth resolution enhancement with ultrasonic reflection microscope for the reflectors of a stainless steel reference specimen and a reference calibration block to be used as the material in nuclear power plants for ISI, PSI. Increased depth resolution can be obtained by taking two, three-dimensional images at more that one frequency and numerically combining the results. As results of the experiment, we could get enhanced images with the rate of contrast in proportion and high quality signal distribution for the image to the changing rate of depth for the reflectors of the two kinds of specimens.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.403-408
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• 1999

In this paper, ultrasonic tomography by the Mode-Converted Rayleigh wave (MCRW) in the back-scattered direction is presented. When a beam with a short pulse and narrow beam width enters a reflector with smooth surface, in general, two major arrivals can be observed in the output waveform: the specular reflection and the radiation of the MCRW from the reflector surface. The time-delay between the two waves is relatively large and thus can be measured easily. This large time-delay is due to the fact that the MCRW is slower than incident wave. In our method, this large time- delay is used for ultrasonic image reconstruction. To effectively detect the MCRW, the arrayed-receiving transducers are circularly arranged around the transmitter. In addition, a deconvolution method is employed to remove specular echo signals for reconstructing the MCRW image.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권12호
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• pp.577-582
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• 2002

The objective of this paper is to produce a weighted graph map for path-planning of an autonomous mobile robot(AMR) based on the measurements from a single ultrasonic sensor, which are acquired when the autonomous mobile robot explores unknown indoor circumstance. The AMR navigates in th unknown space by following the wall and gathers the range data using the ultrasonic sensor, from which the occupancy grid map is constructed by associating the range data with occupancy certainties. Then, the occupancy grid map is converted to a weighted graph map suing morphological image processing and thinning algorithms. the path- planning for autonomous navigation of a mobile robot can be carried out based on the occupancy grid map. These procedures are implemented and tested using an AMR, and primary results are presented in this paper.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.45-48
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• 1995

Visualization of three dimensional medical images has been studied in many ways. For CT and MRI data, 3D rendering schemes are commercially available and widly used. However visualization of ultrasonic 3D data is not popular yet, even though its potentional in medical diagnosis seems very high. In this paper we try to visualize 3D ultrasonic data. The basic method is adopted from the volume rendering technique. Based on the characteristics of the ultrasonic images, 3D visualization algorithm is developed and applied for the 3D image set of a dog heart.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.628-631
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• 2017

정상초음파가 인가된 탄화수소계 연료별/공기 혼합물의 당량비에 따른 연소특성 비교를 실험적 연구 결과로 제시한다. 전파화염의 이미지는 고속카메라를 이용하여 획득하였으며, 이미지 후처리를 통해 연료별 연소특성을 면밀히 관찰하였다. 정상초음파를 인가하면 탄화수소계 연료/공기 예혼합기의 이론당량비조건에서 연소반응을 촉진시킨다는 점을 확인하였다.

• 센서학회지
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• 제20권2호
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• pp.124-130
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• 2011

In this study, in order to evaluate the yield of bubble by ultrasonic cavitation in HIFU sonication, the bubble image analysis was performed. The changing phenomenon of cavitation effect according to the sonication condition was discussed by analyzing the bubble image. Especially the appearance of bubble cloud, the size of micro-bubble, and the yield of bubble were considered. The 500 KHz and 1.1 MHz concave type ultrasonic transducers were used for HIFU sonication. Computer controlled digital camera was used to obtain the bubble image, and the binary image processing(binarization coefficient : 0.15) was performed to analyze them. In results of 500 KHz and 1.1 MHz transducer, the area of bubble cloud was increased in proportion to the rise in sonication intensity($R^2$ : 0.7031 and 0.811). The mean size of single microbubble was measured as 98.18 um in 500 KHz sonication, and 63.38 um in 1.1 MHz sonication. In addition, the amount of produced bubble was increased in proportion to sonication intensity. Through the result of this study and further study for variable image processing method, the quantitative evaluation of ultrasonic cavitation effects in HIFU operation could be possible with the linearity associated with the sonication conditions.

• 대한중풍순환신경학회지
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• 제14권1호
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• pp.102-106
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• 2013

■ Objectives The purpose of the this study was to investigate organization change(pennation angle) of lower extremity muscle in elderly with knee osteoarthritis through ultrasonic image. Also, we examined organizational change of muscle was by influenced after total knee replacement(TKR). ■ Methods Rectus femoris image was taken at 50% of the distance between the anterior superior iliac spine and the superior border of the patella. Vastus medialis image was taken at the most distal insertion level of vastus medialis on the medial border of the patella. measurements included the most distal insertion level of the vastus medialis on the medial border of the patella. ■ Results Change of pennation angle in rectus femoris showed decrease from 5.11° in preoperation to 4.29° in 1 week after operation. Change of pennation angle in vastus medialis showed decrease from 6.94° in preoperation to 5.76° in 1 week after operation. ■ Conclusion We consider decrease of pennation angle after total knee replacement in this study was casued by organizational change of muscle and this pennation angle was influenced force created by muscle. Therefore, we thinks that this pennation angle through ultrasonic image will be available to plane individual muscle exercise program and to confirm muscle mass by muscle strength training.

• 한국음향학회지
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• 제8권4호
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• pp.23-28
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• 1989

본 논문에서는 컴퓨터에 의한 초음파 홀로그램의 구성과 영상 재생방법을 연구하였으며 이를 광학적 재생방법과 비교 분석하였다. 초음파 홀로그램은 초음파 변환자를 기계적으로 c-scan $(128\times128 step)$하여 구성하였고 물체에 대한 영상은 Rayleigh-Sommerfeld 식과 DFT 알고리즘을 이용하여 컴퓨터 재생하였다. 본 실험에서 는 중심주파수가 5MHz이고 촛점 거리가 5cm 인 초음파 변환자와 기계적인 c-scanning 시스템을 사용하여 음향 홀로그래피 시스템을 구성하였고 알루미늄 판에 S자 형태를 새긴 샘플을 제작하여 실험하였다. 실험결과 컴퓨터에 의해 재생된 영상은 실체와 동일한 고질의 영상임을 확인하였다.