• Journal of Power System Engineering
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• v.17 no.6
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• pp.142-148
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• 2013

High-power ultrasonic promotes a chemical reaction by its own energy, thus it has been used for sonochemistry applications. For example, it has been mostly used for mixing, reaction catalyst, dispersion and disintegration. High-power ultrasonic transducer is made with structure based on a Bolt-clamped Langevin type Transducer (BLT), But it has difficulty in the development because degradation of piezoelectric ceramic by the heat generation of BLT. In this study, for a development of the transducer of 25 kHz and 1000 W used in sonochemistry and industrial cleaning, BLT with a hole in its center and tubular type waveguide of the transducer were designed based on finite element method (FEM). The transducer was fabricated based on the design parameter, and the impedance characteristics are measured experimentally and compared with the numerical results.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.65.3-65
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• 2001

In order to apply for pickling line in cold rolling process, a high power magnetostrictive ultrasonic transducer was developed. The transducer is expected to overcome the shortcomings of conventional high power ultrasonic transducers. The transducer consists of Fe-Co-V alloy sheets for the magnetostrictive material, an ultrasonic horn made of Hastelloy to withstand acid solution, and electric driving circuit. In the development, the transducer was designed with the theoretical and numerical methods such as finite element method, and was characterized with experimental water tanks. The developed transducers turned out to be able to generate the sound pressure up to 20,000 Pa, and to be suitable for application ...

• Journal of Magnetics
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• v.4 no.3
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• pp.98-101
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• 1999

In this work we htave constructed an under water sonar transducer using Terfenol-D rod employing open magnetic circuit. Normally Sonar transducer using Terfenol-D was designed under closed magnetic flux return path, and permanent magnet for dc bias marnetic field, but high magnetic field should be applied to the transducer coil for high sound power and it brings temperature increase inside of the transducer. To improve this heat dissipation problem, we have designed an open magnetic circuit type transducer and we can get 200 dB (re. 1 Pa @ 1m) sound power for the input power of 650 VA.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1404-1411
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• 2016

Pipe wall thinning in the secondary piping system of a nuclear power plant is currently a major problem that typically affects the safety and reliability of the nuclear power plant directly. Regular in-service inspections are carried out to manage the piping system only during the overhaul. Online thickness monitoring is necessary to avoid abrupt breakage due to wall thinning. To this end, a transducer that can withstand a high-temperature environment and should be installed under the insulation layer. We propose a thin plate type of embedded ultrasonic transducer based on magnetostriction. The transducer was designed and fabricated to measure the thickness of a pipe under a high-temperature condition. A number of experimental results confirmed the validity of the present transducer.

• Smart Structures and Systems
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• v.21 no.2
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• pp.151-161
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• 2018

A new type of cascade sandwiched piezoelectric ultrasonic transducer is presented and studied. The cascade transducer is composed of two traditional longitudinally sandwiched piezoelectric transducers, which are connected together in series mechanically and in parallel electrically. Based on the analytical method, the electromechanical equivalent circuit of the cascade transducer is derived and the resonance/anti-resonance frequency equations are obtained. The impedance characteristics and the vibrational modes of the transducer are analyzed. By means of numerical method, the dependency of the resonance/anti-resonance frequency and the effective electromechanical coupling coefficient on the geometrical dimensions of the cascade transducer are studied and some interesting conclusions are obtained. Two prototypes of the cascade transducers are designed and made; the resonance/anti-resonance frequency is measured. It is shown that the analytical resonance/anti-resonance frequencies are in good agreement with the experimental results. It is expected that this kind of cascade transducer can be used in large power and high intensity ultrasonic applications, such as ultrasonic liquid processing, ultrasonic metal machining and ultrasonic welding and soldering.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.383-390
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• 2018

Piezoelectric micro-machined ultrasonic transducers for highly directional speaker need DC bias voltage. Most existing power amplifiers are not suitable for use in highly directional transducers because they are based on AC. In addition, since the piezoelectric micro-machined ultrasonic transducer has a large capacitive reactance, the power efficiency of the power amplifier is very low. Thus this paper proposes a new high efficiency power amplifier with DC bias voltage. In addition, by designing a matching circuit to compensate the capacitive reactance of the micro-machined ultrasonic transducer, the power efficiency of the power amplifier increases. The operating characteristics of the proposed power amplifier was verified by an experimental prototype. The proposed power amplifier is expected to be widely used in designing and implementing other related power amplifiers.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.87-90
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• 1995

When the ultrasonic transducer operating at l MHz for use in cleaning semiconductor wafers or other industsrial materials is driven from the MOS-FET DC-to RF inverter, the output power severely depends on the frequency of operation since the quality factor of the transducer is high. In order to tune to the eresonating frequency of the ultrasonic transducer, the drive signal frequency of the MOS-FET power inverter is automatically scananed until the frequency is set at the resonating frequency of the ultrasonic transducer is maximized. The control circuit consists of an output power sensing circuit, a PLL controller, a frequency standard, and other peripheral circuits. The operation was satisfactory when the transducer having an output of 600 W at 1 MHz was used.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.3
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• pp.278-286
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• 2011

The on-line monitoring for the wall thinning in secondary system has been considered one of main issues for the safety of nuclear power plants. To establish the on-line monitoring technique for the pipe wall thinning, the development of the ultrasonic transducer working in high-temperature is very important. In this investigation, the magnetostrictive transducer is concerned for high temperature condition up to $300^{\circ}C$. The magnetostrictive transducer has many advantages such as high working temperature, durability, cost-effectiveness, and shear waves, most of all. A thin Fe-Co alloy patch whose Curie temperature is over $900^{\circ}C$ was employed as a ferromagnetic material for magnetostriction. Wave transduction experiments in various temperature were carried out and the effect of bias magnets was considered together with the dry coupling performance of the transducer. From experimental results, consequently, it was found that the magnetostrictive transducer works stable even in high temperature up to $300^{\circ}C$ and can be a promising method for the on-line monitoring of the wall thinning in nuclear power plants.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.224-227
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• 1999

A high power deep-water sonar transducer of FFR (Free Flooded Ring) type has been designed using a coupled FE-BEM. The present sonar transducer is composed of rectangular piezoelectric ceramics and pie-shaped steels (or the advantage of simple fabrication. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state frequency response for TX and RX displacement modes, directivity patterns, back-scattering patterns, bandwidths, transmitting voltage responses and receiving sensitivity responses. The TV response shows a very high acoustic pressure of 150 dB/lV (ref $1{\mu}Pa$ at 1m) at 1900 Hz. This ultra high power response of the sonar transducer indicates a new possibility of the sonar transducer development.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.817-820
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• 2006

The Tonpilz transducer is one of the essential elements in active sonar application. The characteristics of transducer depend on the piezoelectric ceramics and mechanical elements such as head mass, tail mass, pre-stress rod and so on. One of the important characteristics is electric and mechanical stability of transducer for long term high power transmitting operation. This parer presents the results about long term endurance tests of the underwater acoustic transducer.