• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.256-265
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• 2019

Several types of cymbal transducers used for underwater detection have been studied. Representative types are Moonie, convex cymbal, and concave cymbal transducers. In this study, we analyzed the characteristics of these three types of transducers for underwater broadband projectors and compared them together. First, the influence of structural variables on the acoustic characteristics of the transducers was analyzed. Based on this, we derived the structure of each transducer type to have a specific center frequency and the maximum bandwidth. As a result of comparing the performance of the optimized transducers, the convex cymbal transducer turned out to be best in terms of both broad bandwidth and high power.

• The Journal of the Acoustical Society of Korea
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• v.33 no.2
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• pp.94-101
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• 2014

In this work, we present an underwater acoustic transducer with a cavity-type head mass to achieve a wide frequency bandwidth. We analyzed the effects of design variables on the transducer characteristics, and optimized the structure of the Tonpilz transducer based on the analysis results. Further, validity of the design was verified by manufacturing a prototype of the transducer and measuring its properties. The designed transducer had a far wider -6 dB fractional bandwidth which is 131 % than that of a single mode transducer, and the measured results were confirmed to be in good agreement with the analysis results.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.1
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• pp.27-34
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• 2016

The type of ultrasound transducer used influences the quality of a reconstructed ultrasound image. This study analyzed the effect of transducer type on ultrasound computed tomography (UCT) image quality. The UCT was modeled in an ultrasound simulator by using a 5 cm anatomy model and a ring-shape 5 MHz 128 transducer array, which considered attenuation, refraction, and reflection. Speed-of-sound images were reconstructed by the Radon transform as the UCT image modality. Acoustic impedance images were also reconstructed by the delay-and-sum (DAS) method, which considered the speed of sound information. To determine the optimal combination of transducers in observation, point-source, flat, and focused transducers were tested in combination as trasmitters and receivers; UCT images were constructed from each combination. The combination of point-source/flat transducer as transmitting and receiving devices presented the best reconstructed image quality. In UCT implementation, the combination of a flat transducer for transmitting and a point transducer for receiving permitted acceptable image quality.

• The Journal of the Acoustical Society of Korea
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• v.34 no.3
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• pp.210-218
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• 2015

When the driving voltage of an ultrasound transducer is increased to improve the quality of ultrasound images, heat is generated inside the transducer that can cause patient's skin burn and degradation of transducer performance. Hence, in this paper, a method to disperse the heat of the transducer has been studied. The phased array transducer having 3 MHz center frequency and 32 channels was selected for analyses of the thermal dispersion. First, mechanism of the heat generation was investigated in relation to the transducer operation through theoretical analysis, and material damping and sound pressure amplitude were confirmed to be influential on the heat generation. Further, we investigated the effects of the properties of the materials constituting the transducer on the thermal dispersion through finite element analysis. Based on the analysis results, we determined the thermal properties of the constituent materials that could facilitate the thermal dispersion inside the transducer. The determined thermal properties were applied to the finite element model, and the results showed that the maximum temperature at an acoustic lens contacting with a patient was decreased to 51 % of its initial value.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.107-114
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• 2000

This work is aimed to develop a new type of the Push-Pull ultrasonic transducer that can provide higher sound pressure level and simpler internal structure than conventional types. The driving part of the newly designed transducer is positioned in the middle of the cylinder, and its optimum geometry is determined by using the FEM package, ANSYS. Through FEM model analysis, the effects of all of its geometrical variables such as transducer length, transducer radius, and the edge shape of the end cap have been examined, and the results have led to the optimum geometry. The newly designed transducer has been found to give better performance than that of traditional ones.

• The Journal of the Acoustical Society of Korea
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• v.29 no.7
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• pp.439-447
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• 2010

In this paper, the resonant characteristic of a Tonpilz transducer with a fixed tail mass has been researched and the feasibility to utilize the transducer in that resonant frequency has been analyzed. The additional resonance is occurred by adhering an elastic tube to the tail mass of a conventional Tonpilz transducer and fixing the other end of the tube. The characteristic of this low resonant mode is analyzed by means of the finite element method, then it is shown that this mode is affected by the variation of the stiffness of the tube as well as the mass of the head mass and tail mass. Based on the analysis results, the Tonpilz transducer is designed to meet specific performance conditions.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.199-207
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• 2013

In this paper, a $64{\times}8$ channel 1.75D ultrasonic transducer made of piezoelectric single crystals was designed, fabricated, and evaluated. First, a structure of the transducer was selected to be suitable for wiring on a planar array, and components were fabricated to correspond to the structure. Detailed structure of the transducer was designed through finite element analyses. As main performance factors, the crosstalk between neighboring elements was reduced through the control of kerf width and material, and desired frequency bandwidth of the transducer was achieved by designing the optimal thicknesses of the piezoelectric single crystal and matching layers. An experimental prototype of the transducer was fabricated following the design, and its performance was measured. Then the experimental results were compared with those of the finite element analysis, which led to the evaluation of the transducer developed in this work.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.171-182
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• 2002

The differential electromagnetic transducer for IME(implantable middle ear) system, which have two small permanent magnets glued with the same pole facing each other in the coil, has high vibration efficiency and does not influenced by external magnetic field. In this paper, using finite element method, highly efficient structure of the transducer was proposed and vibration force of the transducer was calculated by electromagnetic theory. And the necessary vibration force of transducer to transmit the sound signal to inner ear when the transducer is attached at stapes was calculated and the design parameters of the transducer were investigated. Using the parameters, the differential electromagnetic transducer was manufactured in small size to implant in confined human middle ear. And it was examined by unloaded and loaded vibration experiment using temporal bone sampled from cadaver.

• The Journal of the Acoustical Society of Korea
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• v.22 no.8
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• pp.629-636
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• 2003

It will be very convenient if the directivity characteristics of ultrasonic transducer array are controllable by the purpose of use in the fields of sonar system or ultrasonic diagnostic system, In this paper, a control method of the directivity characteristics was suggested. The transducer array was consisted of two-layered piezoelectric vibrators. Efficiency of each vibrator is controlled in 2nd harmonic mode by electrical capacitance. Therefore, the beam width of the transducer array can be controlled by changing the capacitance. The directivity characteristics of the array were analyzed experimentally and theoretically. As the results, it is confirmed that -3 dB beam width of main lobe can be controlled in the range of 7.6°∼16.2°.