• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.5
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• pp.80-85
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• 1997

Preventive diagnosis technique of power transforms is very important for highly reliable operation of power systems, and especially that of online transformer is needed in view of economy. Acoustic methods for partial discharge points have been studied abroad since 1960's in earnest. Electric-ultrasonic locating method by which partial discharges are found through detecting the electric and ultrasonic signal generated in partial discharge and ultrasonic-ultrasonic locating method by which partial discharges are found through detecting two ultrasonic signal with two ultrasonic sensor have been researched in our country. By using this ultrasonic-ultrasonic locating method, it was proposed of graphical determination technique of partial discharge points one dimension, two dimension, three dimension. But in locating partial discharges, they have assumed that the number of signal origin is one. So in this study we suggests a method of locating and knowing the number of signal origins when there are several origins by using ultrasonic-ultrasonic method.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.87-87
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• 2003

본 연구는 개의 수태율 향상을 위한 인공 수정적기를 구명하기 위하여 발정개시 후 초음파를 이용하여 난소내 난포발달 상태를 진단하였다. 자연적으로 발정이 개시된 Greyhound 2두에 대해서 초음파기(SA 600S, 메디슨, 한국)와 3.SMHz probe를 이용하여 난포발달에 대한 초음파화상을 얻었다. 외음부가 종창하고 출혈이 확인된 첫날을 발정개시일(Day 1)로 하였으며 발정개시 후 11일째, 13일째 및 15일째 난포발달 상태를 조사한 결과 좌우 난소에 각각 3개 및 4개의 난포가 발달중에 있었으며, 난포의 크기는 좌우 각각 11일째에 6, 9, 17mm(좌측)와 6, 9, 6, 5mm(우측)였으며, 13일째에는 각각 10, 11, 11mm 및 9, 14, 13, 12mm였다. 15일째에는 이미 배란이 일어나서 난포상을 관찰할 수 없었으나 배란흔적은 관찰할 수 있었다. 본 실험에서는 발정개시 후 11, 13, 15일째 0.25$m\ell$ 주입기를 이용하여 그레이하운드 동결정액으로 인공수정하였으며, 이때 동결정액(좋은유전자 Co.)의 융해 후 활력 있는 정자수는 3$\times$$10^{7}$ spermatozoa/dose(0.25$m\ell$)였으며, 자궁경관내 주입기선단의 관통 여부를 촉진한 후 자궁내 정액 주입을 확인할 수 있었다. 난포발달에 대한 초음파 진단결과 Greyhound에 있어서 1회 인공수정시에는 발정개시 후 15일째가 높은 수태를 위한 수정적기라고 사료되었으며 이러한 결과는 Concannon 등(1989)이 배란 후 2일째가 수정적기로 판단한 연구 결과와 유사한 경향을 나타내었다.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.421-426
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• 2006

In examining particulate deposits in the pipes of a chemical vapor deposition (CVD) system, vibration diagnostics is compared and studied against ultrasonic diagnostics, The latter method involves pulsing the outer wall of pipes with an ultrasonic sensor and analyzing the resulting echo to observe particulate deposits inside pipes. Vibration diagnostics examines the existence of particulate deposits by analyzing the difference in the frequencies generated when a vibrator is adhered to the outer wall of pipes. With ultrasonic diagnostics, good test results were obtained only when particulate deposits were attached to the inner wall of the pipes, After some time, however, particulate deposits were not detected properly, as the ultrasonic wave failed to cross the fine gaps created between the inner wall of the pipe and the deposits. The ultrasonic wave bounced back because of the dried particulate deposits on the wall. Thus, it has been proven that the ultrasonic diagnostics is not an appropriate means of examining the particulate deposits in a vacuum, On the other hand, vibration diagnostics succeeded in detecting the particulate deposits regardless of the lapsed time. In conclusion, the vibration diagnostics is being expected as the effective method in monitoring the particulate deposits inside pipes in the CVD system where the desired behavior is reduced frequency along with the particulate deposits in comparison to the case where the pipe is clean.

• The Journal of the Acoustical Society of Korea
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• v.22 no.3
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• pp.208-216
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• 2003

In one dimensional linear array type piezoelectric ultrasonic transducers widely used for medical diagnosis, the acoustic cross talk caused by the structural acoustic coupling between the adjacent piezoelectric elements reduces significantly their performance. In the study, we have proposed an acoustic wall to reduce the acoustic cross talk by wave propagation through the surface the transducer which can not be prevented by conventional kerf and have analyzed using a finite element method the acoustic cross talk level with respect to the shape, size and materials of the acoustic wall mounted on a convex one dimensional piezoelectric ultrasonic transducer. We expect that the simulated results provide us with a valuable information to make an optimized design of the way type ultrasonic transducer minimizing the acoustic cross talk level.

• Journal of radiological science and technology
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• v.32 no.3
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• pp.277-283
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• 2009

It is important to get clinical ultrasonic images of good quality for accurate diagnosis. In this study, it observed the change of ultrasonic images against setting frequency, dynamic range(DR) and type of probes on ultrasonic scanner. In the experiment it evaluated image of LCS (Low Contrast Sensitivity) targets(-15, -6, -3, +3, +6, +15 dB) of a standard ultrasonic test phantoms(539,551, ATS, USA) similar to solid and cystic lesions. Its imaged from convex (C3-7IM) and linear probe (L5-12IM) on SA-9900 (Medison Ltd, Korea) scanner. The images obtained altering the setting parameters which are frequency(gen, pen, res, harmonic) mode and DR($40{\sim}100\;dB$). The quality of images evaluated compare with the nominal LCS value of target and measured LCS value. The results show that there was no significant changing of quality images altering DR 40, 60, 80, 100 dB against frequency in Convex probe but the image being the highest in LCS target at DR 60 dB, harmonic of frequency mode in the -15 dB target close to cystic lesion. In Linear probe, DR 40 dB, harmonic mode at -15 dB LCS target close to nominal value. It discussed necessity of evaluation about ROC(Receiver Operating Characteristic) from the psychological viewpoint and limit of evaluation from quantified images.

• The Journal of the Acoustical Society of Korea
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• v.12 no.2E
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• pp.73-79
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• 1993

전력수요의 증가에 따라 전력계통의 대규모, 고엊압화 되는 현실에서 변압기의 사고는 사회여러분야에 큰 영향을 주게 되었다. 이에 세계 여러나라에서는 변압기 사고 예방진단시스템을 연구하고 있으며 일부는 실제 설치, 운영중에 있다. 본 논문에서는 변압기사고진단의 일환으로 변압기 사고의 원인이 되는 부분방전을 제거할 때 방전점을 예측하여 비용과 시간을 줄이고자 하였다. 부분방전의 위치를 예측하는 방법으로 2개의 초음파 신호의 신호상관법을 이용하였으며 모의 변압기를 통한 실험에서 오차가 4%이하로 비교적 정확한 위치 예측이 가능함을 보여 주었다.

• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.78.2-79
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• 1999

• The Journal of the Acoustical Society of Korea
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• v.12 no.4
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• pp.78-85
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• 1993

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.901-904
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• 2007

Nowadays, in many fields of medical treatment, we can make an observation and a diagnosis of inward disease without using a surgical operation. As one of them, ultra-sound diagnosis system can be available widely in its cost and size compared with other medical instruments. This system also make it possible for us to see the inner parts of the body in real time harmlessly for a long time. So it can be utilized to inspect the movement of heart or fetus and to diagnose an internal disease of the soft tissues. Ultra-sound images can be generated by the reflexive and scattered wave through the pulse generator and so in ultrasound images there exist inherently many affective noised signals. In this paper, we are to take an noise-restrained image and to extract a more affective regions of the images.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.351-352
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• 2004

본 논문에서는 초음파 영상 진단기용 선형어레이 변환기를 장착할 수 있는 수조 와 128 채널의 스위칭 회로를 제작하여 변환기의 각 채널별 음향파워를 측정하였다. 실험은 128 채널 중 하나의 채널이 불량인 어레이 프로브를 대상으로 수행되었다. 측정 결과, 불량 채널의 음향 파워가 다른 채널에 비해 현저히 작게 나타남을 확인하였다.