• Journal of radiological science and technology
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• v.23 no.2
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• pp.33-37
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• 2000

The authors fabricated ultrasonic transducer with PVDF[poly(vinylidene fluoride)] piezoelectric polymer film. When impulse waves were applied to the PVDF ultrasonic transducer, the dependence of the response properties on the backing material with copper was investigated through not only theoretical calculations using Mason's equivalent circuit but also experimental measurements. The experimental pulse response properties agree with those of the theoretical calculations and the pulses were shorter than those for a PZT transducer. If such short-pulse properties are used in an medical ultrasonic image diagnosis apparatus, the resolution of the apparatus will be improved. When the insertion loss was calculated theoretically to the PVDF ultrasonic transducer, the frequency characteristics of its showed wideband frequency.

• Environmental Engineering Research
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• v.11 no.3
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• pp.143-148
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• 2006

The ultrasonics is a new technology in waste activated sludge(WAS) treatment. Ultrasonic treatment is well known method for the break up of microbial cells to extract out a variety of intercellular materials inside microorganism cell. This study was done to investigate the effects of the ultrasonic frequency and power on disruption of biosolids in WAS and to examine the effect on methane production of WAS treated by ultrasonics. Biosolids disruption with ultrasound is more effective at ultrasonic frequency of 40 kHz and power of 0.3 watt/mL. In the digestion with WAS pretreated by sonication time for 10 minute at 40 kHz and 0.3 watt/mL, the total quantity of generated methane increased by 75%, as compared with experimental control(non-treatment).

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.36-41
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• 2002

This study was carried out develope a ultrasonic transducer displacement generator through 26KHz and 38KHz of the frequency phase modulation on the ultrasonic transducer. This system was producted a power output generation such as 100W, 300W, 400W and 600W. Ultrasonic power output had a change of time. We made use of a Thiram hydration and detected it measurement by the ACAO method. It was to decide the result of ultrasonic power supply for time duration and the result of comparison in the 26KHz & 38KHz by UV/VIS spectrophotometer.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.631-636
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• 1987

The design of ultrasonic transducer energy processing systems requires highly reliable command featuring mechanical frequency tracking and constant velocity control of the ultrasonic transducer with an acoustic load. This paper presents a new conceptional instantaneous current resultant control base high-frequency inverter using self turn-off devices driving an electrostrictive ultrasonic transducer system and its optimum control technique, which is implemented by feed-back of the ultrasonic transducer applied voltage and instantaneous velocity of the transducer vibrating system through a Phase-Locked-Loop control scheme. The feedback voltage corresponding to instantaneous velocity is averaged over a half-period with respect to constant amplitude/constant velocity control strategy. Described are the theory of this signal detection technique and the experimental set-up.

• KSBB Journal
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• v.23 no.4
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• pp.297-302
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• 2008

In this work, the amounts of Flavone C-glycosides homoorientin, orientin extracted from Black bamboo by various ultrasonic waves frequency (35, 72, 170 KHz, 300 Watt $\pm$1) time (15, 30, 60 min) and temperature ($25^{\circ}C$) were compared using 50% aqueous ethanol solution. And describesanalysis of the antioxidant potential of Black bamboo using an high-performance liquid chromatography (HPLC) on-line $ABTS^+$antioxidant screening method. In conjunction with the analysis of their 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid ($ABTS^+$) radical scavenging ability. The optimum operating conditions were experimentally determined to analyze the Flavone C-glycosides homoorientin, orientin in the pretreatment ultrasonic extracts. From the results, the effect on extraction yield of variations in frequency, solvent composition and extraction time was investigated. The highest yield of Black bamboo was obtained by ultrasonic waves with a frequency of 72 KHz and an extraction time of 60 min, The extraction frequency 35 KHz ($25^{\circ}C$), time 30 min was selected as an optimal antioxidant activity condition.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.466-472
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• 2016

In this work, a medical linear array ultrasonic transducer working in the range of 20 MHz has been developed for high-resolution ultrasonic imaging. After devising the structure of the transducer suitable for the transmission of high-frequency waves, we optimized the dimension of constituent components. Then, the process to fabricate the transducer was developed to realize the designed structure, and a prototype of the transducer was fabricated and characterized. The center frequency of the fabricated transducer was measured to be 19 MHz, and the fractional bandwidth to be 84.5 %, and the standard deviation of the sensitivity over the entire channels to be 0.74 dB. These measurement results showed good agreement with design data, which confirmed the validity of the high frequency ultrasonic transducer structure developed in this work. It was confirmed that the developed transducer with new structure had wider frequency bandwidth and uniform sensitivity than a conventional 20 MHz transducer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.505-506
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.256-256
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.783-784
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1097-1098
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• 2011