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

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.3
• /
• pp.278-286
• /
• 2022

In this study, a 33-mode Free-Flooded Ring (FFR) transducer was designed to apply piezoelectric single crystal PIN-PMN-PT, which has high piezoelectric constants and electromechanical coupling coefficient. To ensure low-frequency high transmitting sensitivity characteristics with a small size of FFR transducer, the commercial FFR transducer based on piezoelectric ceramics was compared. To develop the FFR transducer with broadband characteristics, a piezoelectric segmented ring structure inserted with inactive elements was applied. The oil-filled structure was applied to minimize the change of acoustic characteristics of the ring transducer. It was verified that the transmitting voltage response, underwater impedance, and beam pattern matched the finite element numerical simulation results well through an acoustic test. The difference in the transmitting voltage response between the measured and the simulated results is about 1.3 dB in cavity mode and about 0.3 dB in radial mode. The fabricated FFR transducer had a higher transmitting voltage response compared to the commercial transducer, but the diameter was reduced by about 17 %. From this study, it was confirmed that the feasibility of a single crystal-applied FFR transducer with compact size and high-power characteristics. The effectiveness of the performance prediction by simulation was also confirmed.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.11a
• /
• pp.144-145
• /
• 2005

In this study, we have developed the high resolution multichannel seismic data acquisition system and shallow marine seismic source. It is easy to operate our source system which utilizes piezoelectric transducer of high electrical power. According to water depth, survey condition and purpose, transducer number of source system can be easily changed in order to maximize field applicability. In the recording part, we used 24 bits and 8 channel high speed A/D board in order to achieve the improvement of data quality and the efficiency of data acquisition. The developed system was tested and varied with the data acquisition parameters such as source-receiver offset, and transducer number versus water depth for the field application.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.959-960
• /
• 2013

• Proceedings of the KIPE Conference
• /
• 2013.11a
• /
• pp.29-30
• /
• 2013

본 논문에서는 수중통신용 Parametric Array Transducer를 구동하기 위한 고효율 전력증폭기를 제안한다. 수중전력증폭기는 증폭부와 전원부로 나뉘며 증폭부는 Class B push-pull type의 전력증폭기를 사용하며 전력증폭기 구동을 위한 전원부는 기존의 일정전압이 아닌 가변전압을 얻는 Phase-shifted PWM AC/DC 컨버터를 사용하여 고효율로 동작한다. 증폭부는 Class B push-pull type 증폭기를 사용함으로써 뛰어난 선형성이 보장되며 전원 또한 ET(Envelope Tracking)기술을 적용한 가변전압 AC/DC컨버터를 사용하여 고효율로 동작한다. 본 논문에서는 고 효율 수중전력증폭기와 가변전압 AC/DC컨버터의 전력회로를 제시하고 시뮬레이션과 실험을 통하여 특성을 확인하였으며, 수중음향센서를 위한 전력증폭기로 유용하게 사용 될 것을 예상한다.

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

• Journal of the Korean Society for Nondestructive Testing
• /
• v.24 no.2
• /
• pp.180-185
• /
• 2004

Conventional ultrasonic examination to detect micro and small surface cracks is based on the pulse-echo technique using a normal immersion focused transducer with high frequency, or an angle-beam transducer generating surface waves. It is difficult to make an automatic ultrasonic system that can detect micro and small surface cracks and position in a large structure like steel and ceramic rolls, because of the huge data of inspection and the ambiguous position data of the transducer. In this study, a high-precision scanning acoustic microscope with a 10MHz large-aperture transducer has been used to assess the existence, position and depth of a surface crack from the real-time A, B, C scans obtained by exploiting the ultrasonic diffraction. The ultrasonic method with large aperture transducer has improved the accuracy of the crack depth assessment and also the scanning speed by ten times, compared with the conventional ultrasonic methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.9
• /
• pp.845-852
• /
• 2012

Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention from not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation on the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100 mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6 % at 2 m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfering distance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.04a
• /
• pp.771-776
• /
• 2012

Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention of not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation for the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6% at 2m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfer distance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.12
• /
• pp.1063-1070
• /
• 2008

The performance of an acoustic transducer is determined by the effects of many design variables, and mostly the influences of these design variables are not linearly independent of each other. To achieve the optimal performance of an acoustic transducer, we must consider the cross-coupled effects of the design variables. In this study, the variation of the performances of underwater acoustic transducer in relation to its structural variables was analyzed. In addition, the new optimal design scheme of an acoustic transducer that could reflect not only individual but also all the cross-coupled effects of multiple structural variables, and could determine the detailed geometry of the transducer with great efficiency and rapidity was developed. The validation of the new optimal design scheme was verified by applying the optimal structure design of a flextensional transducer which are the most common use for high power underwater acoustic transducer. With the finite element analysis(FEA), we analyzed the variation of the resonance frequency, sound pressure, and working depth of a flextensional transducer in relation to its design variables. Through statistical multiple regression analysis of the results, we derived functional forms of the resonance frequency, sound pressure, and working depth in terms of the design variables. By applying the constrained optimization technique, Sequential Quadratic Programming Method of Phenichny and Danilin(SQP-PD), to the derived function, we designed and verified the optimal structure of the Class IV flextensional transducer that could provide the highest sound pressure level and highest working depth at a given operation frequency of 1 kHz.