• The Journal of the Acoustical Society of Korea
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• v.30 no.6
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• pp.344-352
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• 2011

In this paper, the resonant characteristic of a Tonpilz transducer with a fixed tail mass has been studied by means of an equivalent circuit approach. An equivalent circuit has been designed to describe the characteristic of a Tonpilz transducer that has an additional resonance because of its fixed tail mass. The transmitting voltage response of the transducer calculated by the designed circuit has been compared with that by the FEA (finite element analysis) to confirm the validity of the circuit. This equivalent circuit approach produces identical results with the FEA, in which the variation of resonant frequencies and TVR has been clearly figured out in relation to the stiffness of the mounting fixture and the mass of the tail mass. The suggested equivalent circuit can be utilized to figure out the characteristics of the Tonpilz transducer more efficiently than FEA that requires much calculation time and revision of the models in accordance with the variation of design variables.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.656-664
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• 2017

This paper presents the design and fabrication of a high power piezoelectric ultrasonic surgery unit for multi-purpose dental implantation. A conventional piezoelectric ultrasonic surgery units consists of a transducer and a tip. However, the drawback of this simple structure is that the output performance of the transducer considerably changes with the change of the tips. An ultrasonic surgery unit that has an additional booster between the transducer and the tip can solve this problem to some extent; for this, an optimal structural design for the transducer is required. We used the Bolted Langevin Transducer (BLT) as the basic transducer; it consists of piezoelectric ceramics and a metal body. It's structure was optimized using mathematical methods to determine the length and radius of the tail and head masses. Additionally, the booster was also subjected to the same methods. Using these mathematical methods, optimal results in terms of the resonance frequency (24.96 kHz), displacement ($14.27{\mu}m$), and pressure (2.8 MPa), could be obtained. The validity of this proposed surgery unit was confirmed experimentally, exhibiting a cutting force of around 7% higher than that of a conventional surgery unit.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.120-127
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• 2015

In this paper, a linear-array transducer capable of overcoming the faults of a single element and phased array transducers with convex shape for non-destructive ultrasonic testing was designed and fabricated. A 5.5 MHz linear-array transducer was designed using the PiezoCAD program based on the KLM analysis and the PZFlex program based on the FEM analysis. A 2-2 composite structure was employed to achieve broad-band characteristics. A 128 element linear-array transducer was fabricated and its performance was compared with the simulation results. The center frequency of the fabricated transducer was 5.5 MHz and the -6 dB frequency bandwidth was 70 %. Thus, we expect that the designed transducer can provide an effective inner image of the test material during non-destructive ultrasonic testing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.1-11
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• 2000

A low frequency, high power hydroacoustic transducer with 7 tonpilz piston elements assembled in a circular array suitable for marine application, such as the transmission of underwater information and the development of new fisheries resources in the deep sea zone was designed. A modified Mason's model was applied to monitor and to simulate the transducer behavior at each step during the fabrication. The in air, and in water constructed tonpilz transducer was tested experimentally and numerically by changing the size and the type of the material for head, tail and acoustic window. Also, the developed transducer was excited by pulse signals and the received waveform was analyzed. The resonance peaks in the transmitting voltage response(TVR) of a single tonpilz element without housing were observed at 11.33kHz in air and 10.93kHz in air and 10.93 kHz in water, respectively, with the overall electrical-acoustic efficiency of 43.7%. The value of TVR of single tonpilz element with aluminum housing in water was 129.87dB re 1 $\mu$Pa/V at 12.25 kHz with the frequency bandwith of 2.15 kHz and half beam angle of 30.2$^{\circ}$at -3dB.The resonance peaks in the transmitting voltage response of the 7 element circular transducer were observed at 11.50 kHz in air and 11.45 kHz in water, respectively. The value of TVR in water 144.84 dB re 1$\mu$Pa/V at 11.5kHz with the frequency bandwith of 4.25 kHz and the half beam angle of $22.3^{\circ} $ at -3dB.Reasonable agreement between the experimental measurements and the theoretical predictions for the directivity patterns, TVRs and the impedance characteristics of the designed transducer was achieved.

• Journal of the Korean Society for Nondestructive Testing
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• v.37 no.1
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• pp.37-43
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• 2017

Ultrasonic transducers with high resolution and resonant frequency are required to detect small defects (less than hundreds of ${\mu}m$) by ultrasonic testing. The resonance frequency and resolution of an ultrasonic transducer are closely related to the thickness of piezo-electric materials, backing materials, and the electric impedance matching technique. Among these factors, electrical impedance matching plays an important role because it can reduce the loss and reflection of ultrasonic energy differences in electrical impedance between an ultrasonic transducer and an ultrasonic defects detecting system. An LC matching circuit is the most frequently used electric matching method. It is necessary for the electrical impedance of an ultrasonic transducer to correspond to approximately $50{\Omega}$ to compensate the difference in electrical impedance between both connections. In this study, a 15 MHz immersion ultrasonic transducer was fabricated and an LC electrical impedance circuit was applied to that for having broad-band frequency characteristic.

• The Journal of the Acoustical Society of Korea
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• v.34 no.2
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• pp.117-129
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• 2015

A parametric array is a nonlinear phenomenon that generates a narrow beam of low-frequency sound using the nonlinearity of the medium. The low-frequency sound so generated has a low sound pressure compared with that of sound generated directly. Consequently, a transducer that can generate a primary wave with high directivity and level is required. This study designed, fabricated, and evaluated a multi-resonance transducer as a parametric array source. The designs of the unit transducers and array transducer were based on an analysis model. The design process was repeated to fabricate the optimum transducer. The fabricated transducer array can generate a 189 dB, 190 dB primary wave level at 6.3 m and a 134 dB difference frequency wave using the parametric array phenomenon. The difference frequency wave has a frequency of 15 kHz and high directivity with an $8^{\circ}$ half power beam width in a $12{\times}18{\times}10m$ water tank.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.1
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• pp.45-48
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• 2016

The treatment of obesity have been developed various devices for the treatment of obesity, the ultrasound is to be made after the state changes to become easy fat decomposition by heat and vibrations to facilitate the flow of blood and lymph fatty acid released into the blood. There is such ultrasonic transducer array is used in obesity therapy focusing angle of the transducer array and the frequency may have a significant impact on the degradation of fat. In this paper, we set the frequency that reaches the shortest time to a set temperature 27kHz, 1MHz, by applying a transducer with a diameter of 5mm, 10mm, 16mm for the frequency of 3MHz, obtain the wavelength and near the stomach in order to set the frequency of the transducer array, which was set to the focusing angle of the transducer with three contact surfaces. As a result, the time to reach the set temperature was short days when 3MHz frequency, the focusing angle is titrated is $40^{\circ}$.

• Journal of Sensor Science and Technology
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• v.14 no.5
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• pp.322-330
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• 2005

A new type of transducer, piezoelectric floating mass transducer (PFMT) which has advantages of piezoelectric and electromagnetic transducer has been proposed and implemented for the implantable middle ear hearing devices. By the uneven bonding of piezoelectric material to the inner bottom of transducer case, the PFMT can vibrate back-and-forth along the longitudinal axis of the transducer even though the piezoelectric material within the cylindrical case produces only the bilateral expansion and contraction according to the applied electrical signal. To improve efficiency of the PFMT, the multi-layered piezoelectric material has been adapted. The small number of components in the PFMT enables the simple manufacturing and the easy implanting into the middle ear. In order to examine the characteristics of vibration, mechanical modeling and finite element analyses of the proposed transducer have been performed. From the result of theoretical analyses and the measured data from the experiment, it is verified that the implemented PFMT can be used in implantable middle ear hearing devices.

• The Journal of the Acoustical Society of Korea
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• v.27 no.6
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• pp.271-278
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• 2008

The electro-mechanical characteristics were theoretically analyzed for the wideband ultrasonic transducer made of non-uniform thickness piezoelectric vibrator. This paper proposes a combination of exponential functions which describes the thickness variation along the length of the vibrator to derive the input admittance and power transfer function of the transducer. The bandwidth and the power transfer function of the transducer were investigated while the lateral shape of the vibrator changes. The results showed there is an optimum shape for the wideband characteristics of the transducer, and the bandwidth has increased up to over 100% as the ratio of minimum value of thickness to maximum value decreases. However, the power transfer function had a downward trend as the ratio of thickness decreases. Also we confirmed that even though the value of transfer function increases as the length of the piezoelectric vibrator increases, the shape providing wideband characteristics is very limited. It means that precision processing is required to manufacturing a wideband ultrasonic transducer with high efficiency.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.1
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• pp.77-84
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• 2014