• 한국해양공학회지
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• 제22권4호
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• pp.8-13
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• 2008

In this study, an investigation of shear wave ultrasonic technique was carried out to detect stacking orientation error for CF/Epoxy quasi-isotropy composite laminates. The ultrasonic shear wave is particularly sensitive to ply orientation and layup sequence in tire CF/Epoxy composite laminates. In the manufacturing of composite laminates, it is important that layup errors be detected in samples. In this work, an effect was mack to develop shear wave techniques that can be applied to composite laminates. During testing, the mast significant problem is that the couplant conditions do not remain the same because of its changing viscosity. The design and use of a shear ware transducer would greatly alleviate the couplant problem. A pyramid of aluminum, with isosceles triangle (two 45o angles) sides, was made to generate shear waves, using two longitudinal transducers based on an ultrasonic-polarized mechanism. A signal splitter was connected to the pulser jack on a pulser/receiver and to the longitudinal transducers. The longitudinal transducers were mounted with mineral oil, and the shear transducer was mounted with burnt honey on the bottom as a receiver. The shear wave was generated at a maximum and a minimum based on the ultrasonic-polarized mechanism. Results show it is feasible to measure layup error using shear wave transducers on a stacking of prepregs in composites.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2006년도 공동학술대회 논문집
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• pp.101-106
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• 2006

최근 디지털 기술이 해양 탄성파탐사에 적용되면서 자료처리의 기술이 개발되었고, 다중채널 해양 탄성파탐사가 보급되기 시작하여 고해상 해양 탄성파탐사의 성과를 거두었다. 해양 탄성파탐사에 사용되는 음원의 주파수 특성에 따라 여러 가지 목적의 탐사가 이루어지는데, 투과심도를 높이기 위해 저주파 성분이 사용되며, 해상도를 높이기 위해 고주파 성분이 사용된다. 본 연구에서는 다중채널 해양 탄성파탐사 시스템에 다중 음원을 사용함으로써 저주파 성분과 고주파 성분의 지층단면도를 동시에 취득할 수 있었다. 서로 다른 투과심도와 해상도의 지층단면도를 이용하여 보다 정밀한 지층해석이 가능할 것으로 보인다. 본 연구에 사용된 다중음원 시스템은 저주파 음원인 버블펄서(Bubble Pulser, 400Hz)와 고주파 음원인 스파커(Sparker, 1.5kHz)로 구성되었다.

• 전자공학회논문지
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• 제51권12호
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• pp.66-71
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• 2014

본 논문에서는 초음파 의료 영상 시스템을 위한 아날로그 front-end 집적회로를 $0.18-{\mu}m$ 표준 CMOS 반도체 공정을 이용하여 설계하였다. 제안 된 front-end 회로는 2.6 MHz에서 15-V 고전압 펄스 신호를 생성하는 송신부와 고전압 차단 스위치 및 저전력 저잡음 증폭기에 해당하는 수신부를 모두 포함하고 있으며, 동작 모드에 따라서 송신부의 출력 드라이버를 수신단의 스위치 회로로 재구성이 가능하도록 설계를 하여 기존 front-end 회로와 비교하였을 때 한 채널 당 70% 이상의 칩 면적을 줄일 수 있다. 설계 된 단일 채널 front-end회로는 $0.045mm^2$ 이하의 작은 칩 면적을 차지함으로써 다중 어레이 방식의 초음파 의료 영상 시스템에 적용 시 작은 면적으로 구현이 가능하다.

• 비파괴검사학회지
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• 제19권4호
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• pp.294-299
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• 1999

본 논문에서는 로타(rotor)의 초음파 탐상 결과의 신뢰성을 향상시키기 위하여 수직탐촉자에 대한 교정시스템을 개발하였다. 본 시스템은 신호처리부 (오실로스코프, 스펙트럼 분석기, 송/수신기), 표준시험편 프로그램으로 구성되어 있으며, 교정을 위한 신호처리는 높은 정밀도로 빠르게 수행할 수 있도록 구성되어 있다. 개발된 시스템을 이용하여 로타 검사에 사용되고 있는 초음파 탐촉자를 교정하고 있으며, 신뢰성 있는 정밀도와 감도를 얻을 수 있었다.

• 한국정밀공학회지
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• 제16권7호
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• pp.32-39
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• 1999

Digital signal processor (DSP) is used to obtain the peak value and the time difference of ultrasonic signals, to make digital filter, and to derive mathematical transformation from analog circuit. In this study, C-scan system and control program have been developed to high speed data acquisition. This system consists of signal processing parts (DSP, oscilloscope, pulser/receiver, digitizer), scanner, and control program. The developed system has been applied to a practical ultrasonic testing in overlay weld, and demonstrated high speed with precision

• Asian-Australasian Journal of Animal Sciences
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• 제8권2호
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• pp.175-178
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• 1995

Semen was collected from Taiwan commercial local chickens, the diluted sperm suspension were placed in the Gene Pulser cuvette for electroporation. The motility, mortality and abnormality of spermatozoa were evaluated. The fertility and hatchability were also investigated. The results showed that smaller motility and greater mortality or abnormality than the control were found when the capacitances were increased either for spermatozoa treated with small capacitances(0.25, 1, 3 and $25{\mu}$ FD) or treated with high capacitances (125, 250, 500 and $960{\mu}$ FD). In general, greater field strengths also resulted in smaller motility and greater mortality or abnormality of spermatozoa. Although the electroporation decrease the fertility there were no effect on the hatchability.

• 한국수산과학회지
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• 제53권2호
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• pp.209-217
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• 2020

The purpose of this study was to compare the model-predicted and experimentally measured target strength (TS) of golden cuttlefish Sepia esculenta cuttlebones. Ultrasonic signals used to estimate frequency-dependent TS and the speed of sound in cuttlebones were measured by pulse-echo and through-transmission techniques, using a chirp sonar system and an ultrasonic pulser/receiver system under controlled laboratory conditions. The model appeared to slightly underestimate the predicted TS values in the frequency range of 100-160 kHz. However, there was good agreement between the predicted and measured TS values in the frequency range of 160-200 kHz. The significant similarity between the model-predicted and experimentally measured TS values supports the use of the Kirchhoff-ray mode (KRM) model for acoustic scattering analysis of cuttlebones. Accordingly, we concluded that the KRM model can be used as a tool to evaluate the frequency-dependent variability of TS due to changes in golden cuttlefish swimming depth.

• Tribology and Lubricants
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• 제26권6호
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• pp.341-345
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• 2010

The NAUT(Non contact Air coupled Ultrasonic Testing) is one of the ultrasonic wave inspection methods. It compensates High power ultrasound Pulser Receiver, pre-amp, air probe of high sensitivity in air to generate loss energy by NAUT methods. Generally, in case of ultrasound inspection, it applies contact methods by using couplant. However it can inspect of UT without couplant by this NAUT. The ultrasound transmission reception is composed in stable condition in NAUT. It can inspect high low material or the specimen of rough part, the narrow spot, too. The spot welding is applying the inosculation of automobile component, car body, all boards. The CFRP is necessity of NDE because of the solidity changes material according to lamella tearing. Therefore it checked on realization whether and commercialization in the spot welding and CFRP inspection that the NAUT would be applied them.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.209-210
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• 2006

Digital technology has been applied to marine seismic survey to develop data processing technology and multi-channel marine seismic survey. In result, high-resolution marine seismic survey ended in a success. Surveys are conducted for various purposes using various frequencies of acoustic sources. A low frequency source is used for deeper penetration and a high frequency source is used for higher resolution survey. In this study, a multi-source system was used for multi-channel marine seismic survey to acquire seismic sections of both low and high frequencies. Variations of depth of penetration and resolution would be used to achieve more accurate analysis of formations. In this study, the multi-source system consists of Bubble Pulser(400 Hz) for low frequency source and Sparker(1.5 kHz) for high frequency source.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2009년도 특별 심포지엄
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• pp.73-87
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• 2009

Geophysical survey for unconformity-type uranium deposit applied to this study area in Athabaska Basin, Canada were carried out airborne TEM and magnetic, resistivity-induced polarization (DC-IP), puser seismic reflection and well-logging method. The results of airborne survey interpreted the lithological boundary, geological structures, and conductors. Also, these results decided to main targets for ground DC-IP survey. The Low resistivity and the high chargeability slices of 3D modeling interpreted from DC-IP survey response for conductors related to hydrothermal alteration zones and fault-controlled graphitic zones occurring at the unconformity-type uranium deposit, and they confirmed by diamond drilling. Seismic results interpreted to lake bottom surface, alluvium layer and intra-sandstone faults. We suggest the resonable field data acquisition of DC-IP method on the land or the lake in Athabaska Basin.