• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1229-1237
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• 2003

The production of hydrogen fuel depends basically on the water electrolysis. The ultrasonic effects the decrease of the overpotential in a water electrolysis. A study on the overpotential which activates the hydrogen production is the core to elevate the hydrogen production efficiency on the principle. A pressure sensor system by a new idea is developed and applied. Solutions are 4 kinds of KOH concentration such as 0%, 10%, 20%, and 30%. Two frequency bands of the ultrasonic transducer are 28kHz and 2MHz. The directions of ultrasonic forcing are the vertical direction and the horizontal direction. The temperatures are two states, i.e., no constant and constant. Experiments are carried out sequentially in order in three cases of no ultrasonic forcing, ultrasonic forcing, and ultrasonic discontinution. In results, it is clarified that the ultrasonic effects the decrease of overpotential to elevate the efficiency of hydrogen production.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.707-710
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• 2007

The sensor network by using Utrasonic transceiver is concerned about the dampness of the signals caused by distance among the nodes, the distortion for speed of data trasmission and the transport protocol. The motes are sized $50mm\times60mm$, the ultrasonic analog part sized $30mm\times40mm$ and record 2% error rate for data transport.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1005-1009
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• 2001

The application of the ultrasonic nozzle has been extended because it is possible atomization of liquid material. In this study, the driving characteristics of the ultrasonic nozzle on the driving circuit were investigated. And the characteristics of the ceramic oscillator were investigated for the temperature stability. The ceramic oscillator were made the Pb[(Sb$\sub$1/2/,Nb$\sub$1/2/)$\sub$0.035/-(Mn$\sub$1/3/Nb$\sub$2/3/)$\sub$0.065/- (Zr$\sub$x/Ti$\sub$l-x/)$\sub$0.9/]O$_3$with mole ratio of Zr/Ti. The ceramis oscillator were need the curie temperature of the over 300[$^{\circ}C$] for the temperature stability. When the Zr/Ti ratio was 49/51, it's curie temperature is 322[$^{\circ}C$] and the electromechanical coupling factor(k$\sub$p/) and mechanical quality factor(Q$\sub$m/) showed the values of 0.555, 1,214, respectively The resonance frequency of ceramic oscillator were from 40KHz to 45KHz. So that, the driving circuit were made a possibility that the frequency are variable. The driving current of ultrasonic nozzle showed the value of maximum 80[mA]. Also, The surface temperature of ceramic oscillator showed 80[$^{\circ}C$] at driving time 10[min]. We knew that the ultrasonic nozzle had stabile driving above 10[min.].

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.525-532
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• 1995

In this paper, a new try to measure nonlinear propagation characteristics of the pulse along blood vessel by using bispectral analysis is introduced, and the possibility of its application to the medical diagnosis is shown. In this method, the waveforms of pulse motion of blood vessel at two separated measuring points on the wall were detected from Doppler frequency modulation of transmitted probing ultrasonic waves. Then the auto- and crossbispectrum of detected waveforms are calculated to estimate the quadratic NTF (nonlinear transfer function) between the two measuring positions. In order to show relationships between the NTF and the nonlinear propagation characteristics, computer simulations have been performed. As the propagation distance increases, harmonic frequency components in NTF increases broadly due to the nonlinear effect in the propagation of blood pulse. In order to represent this phenomena quantitatively, we propose a new parameter, dispersion ratio of WTF. Basic experimental system was constructed by using 3.5MHz probing ultrasonic waves and the preliminary experiments were carried out on ague phantom and human body. Experimental results showed the validity of the measurement system enoughly.