• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1245-1246
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• 2015

광대역 표면 탄성파(Surface Acoustic Wave)를 이용하여 도파로 층의 빛을 특정 각도로 변조하여 편향 휴대용 홀로그램 디스플레이를 구현하기 위한 음향 광학(Acoustic-Optic) 장치를 개발했다. 개발된 시스템은 프리즘, 도파로층, 표면탄성파를 일으키는 IDT 및 스크린으로 구성된다. 도파로내에서 전파하는 빛은 표면탄성파에 에너지가 가해지지 않으면 도파로층의 진행중 경로 변화가 발생하지 않지만 표면 탄성파에 에너지를 가하면 빛의 편향된다. 큰 편향 각도와 고효율을 위해서 표면탄성파의 파워, 표면탄성파의 중심주파수, IDT aperture length, waveguide thickness 등을 조절하여 빛 편향각도 및 효율변화를 관찰하였다.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.351-356
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• 2012

Ultrasonic cavitation is a physical phenomenon that generates and collapses microbubbles in media (mainly fluids) under conditions of strong ultrasonic irradiation. In this study, changes in the ultrasonic acoustic characteristics of bubble clouds in relation to ultrasonic irradiation were observed by the quantitative evaluation of cavitation yields. Concave-type single ultrasonic transducers with center frequencies of 500 kHz and 1.1 MHz were used to produce cavitation, and 2.25 MHz interference ultrasonic waves that would traverse any bubble clouds generated were used to analyze the cavitation. The parameters used for the evaluation of cavitation yields (changes in the center frequency, attenuation characteristics, and the propagation time of penetrating waves) were analyzed in relation to the cavitation-generating conditions (irradiation intensity, excitation signal, and center frequency). On the basis of these results, correlations between the changes in the center frequency and irradiation intensity were identified. Although the correlation coefficient was low, notable changes were observed in the center frequency under certain irradiation conditions. Attenuation trends in the interference ultrasonic waves showed high correlations with all the irradiation conditions, and it was noted that these trends were not affected by the forms of cavitation generated. No differences in the propagation time were observed among different irradiation conditions. These findings suggest that bubble yields can be quantitatively evaluated effectively by evaluating the diverse irradiation conditions and that such a quantitative evaluation could be used to study the basic cavitation phenomenon occurring in high-intensity ultrasonic wave treatment.