• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.137-146
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• 2019

The ultrasonic phased arrays are used for treating tumors in the human body by the focus control of the acoustic pressure at the desired position. The magnitude and phase of the surface acoustic pressure in each ultrasonic transducer is controlled by the magnitude and phase of the applied voltage to it. In this paper, the relationship between the applied voltage and the surface acoustic pressure of the ultrasound transducer is modelled, and the desired voltage is realized by PWM technique. The validity of the proposed method is verified by computer simulation of the focus control of a ultrasonic phased array composed of 61 ultrasonic transducers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.224-228
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• 2005

Dynamic control tests for Backhole as a dynamic damper were performed. For the forced oscillation generated by pressure drop in the feed line and internal wave analysis of swirl injector, hydrodynamic pulsator and 1D visualization model injector was produced, respectively We focus on effect of Backhole as a dynamic damper instead of a acoustic one. So, the breakup length and film thickness of liquid sheet on the steady state and the forced oscillation state have been measured and compared.