• E2M - 전기 전자와 첨단 소재
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• 제9권8호
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• pp.825-830
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• 1996

In this study, Characteristics of Ultrasonic Transducer fabricated with porous piezoelectric resonator, 3-D underwater object restoration using the self made ultrasonic transducer and modified SCL(Simple Competitive Learning) neural network are investigated. The self-made transducer was satisfied the required condition of ultrasonic transducer in water, and the modified SCL neural network using the acquired object data 16*16 low resolution image was used for object restoration of $32{\times}32$ high resolution image. The experimental results have shown that the ultrasonic transducer fabricated with porous piezoelectric resonator could be applied for SONAR system.

• The Journal of the Acoustical Society of Korea
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• 제25권3E호
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• pp.110-114
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• 2006

In a previous theoretical paper, we have derived a unified formula by considering 2-D coupled mode vibrations. The unified formula for electromechanical coupling coefficient of piezoelectric resonator was verified experimentally. The capacitance change near the resonant frequency was investigated to estimate the effective coupling coefficient of the resonator instead of the conventional method based on I-D model. The susceptance spectra were measured for the seven samples of piezoelectric resonator with different aspect ratio. Excellent agreement between theoretical and experimental results was obtained.

• 대한전자공학회논문지
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• 제23권4호
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• pp.515-521
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• 1986

Performances of a piezoelectric ultrasonic transducer are analyzed considering the internal losses of a piezoleelctric material and fabricated layers. The KLM-model is adopted for the equivalent circuit of a piezoelectric resonator, and the attenuation coefficient is introduced to represent the internal losses of the transducer. The attenuation coefficient of a piezoelectric resonator is inversely proportional to the maximum value of the input electrical resistance, and is confirmed to be an efficient parameter for the analysis of the considerable lossy piezo-electric resonator operating in a thickness mode. Also, the experimentla RTII is obtained by pulse-echo method. The experimental result is deviated from the predicted one within 3 dB over the 20dB frequency bandwidth.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.156-159
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• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be fabricated as monolithic integrated devices with compatibility to semiconductor process, leading to small size, low cost and high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible Suspended FBAR using surface micromachining. It is possible to make Si$_3$N$_4$/SiO$_2$/Si$_3$N$_4$membrane by using surface micromachining and its good effect is to remove the substrate silicon loss. FBAR was made on 2$\mu\textrm{m}$ multi-layered membrane using CVD process. According to our result, Fabricated film bulk acoustic wave resonator has two adventages. First, in the respect of device Process, our Process of the resonator using surface micromachining is very simple better than that of resonator using bull micromachining. Second, because of using the multiple layer, thermal expansion coefficient is compensated, so, the stress of thin film is reduced.

• 소음진동
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• 제5권4호
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• pp.577-583
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• 1995

The sandwich type piezoelectric resonator is widely used for the acoustic sources of underwater acoustic transducers, whose important design parameters are shapes, materials, dimensions and supporting methods. Practical design method of resonators consists of manufacturing, experiments and modification so that it requires much time and expenses. In this study, an analytical design method of sandwich type piezoelectric resonators is presented based on the nonlinear optimization technique. The proposed method is applied to the design of an example resonator model in order to maximize the output powers. For the investigation of performance according to the division and their electrical connection, three types of resonators are manufactured. In addition, their dynamic characteristics such as electrical admittance and transmitting voltage response are measured and compared.

• E2M - 전기 전자와 첨단 소재
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• 제10권9호
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• pp.916-921
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• 1997

In this study Characteristics of 3-D underwater object recognition independent of translation using the self-made ultrasonic sensor fabricated with porous piezoelectric resonator and presented. The sensor was satisfied with requirement of ultrasonic sensor. The recognition rates for the training data and the testing data are 97.45 and 91.25[%] respectively using the self-made ultrasonic sensor and SCL(Simple Competitive Learning) neural network. According to the experimental results It is believed that the self-made ultrasonic sensor can be applied as sensor of SONAR system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.316-319
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• 1996

In this study, characteristics of ultrasonic transducer fabricated with porous piezoelectric resonator are investigated, 3-D underwater object recognition using the self-made ultrasonic transducer and SOFM(Self-Organizing Feature Map) neural network are presented. The self-made transducer was satisfied the required condition of ultrasonic transducer in water, and the recognition rates for the training data and the testing data were 100 and 95.3% respectively. The experimental results have shown that the ultrasonic transducer fabricated with porous piezoelectric resonator could be applied for sonar system.

• 한국전기전자재료학회논문지
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• 제18권2호
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• pp.159-163
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• 2005

This paper gives characterization of ZnO thin film deposited by RF magnetron sputtering method, which is concerned in deposition process and device fabrication process, to fabricate solidly mounted resonator(SMR)-type film bulk acoustic resonator(FBAR). A piezoelectric layer of 1.1${\mu}{\textrm}{m}$ thick ZnO thin films were grown on thermally oxidized SiO$_2$(3000 $\AA$)/Si substrate layers by RF magnetron sputtering at the room temperature. The highly c-axis oriented ZnO thin film was obtained at the conditions of 265 W of RF power, 10 mtorr of working pressure, and 50/50 of Ar/O$_2$ gas ratio. The piezoelectric-active area was 50 ${\mu}{\textrm}{m}$${\times}$50${\mu}{\textrm}{m}$, and the thickness of ZnO film and Al-3 % Cu electrode were 1.4 ${\mu}{\textrm}{m}$ and 180${\mu}{\textrm}{m}$, respectively. Its series and parallel frequencies appeared at 2.128 and 2.151 GHz, respectively, and the qualify factor of the resonator was as high as 401.8$\pm$8.5.

• E2M - 전기 전자와 첨단 소재
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• 제10권6호
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• pp.562-569
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• 1997

The resonance characteristics on vibration mode of a transverse type ceramic resonator and the output voltage characteristics of a piezoelectric ceramic transformer are discussed in the effects of partial electrode arrangement (one sided, centered and both sided). A resonance characteristics of resonator depended strongly on both a vibration mode and a electrode structure because of a strain distribution. The maximum resonance current of a piezoelectric ceramic transformer [PCT] with partial centered electrode appeared in λ/2 mode, and that of a PCT with partial both sided electrode appeared in 3λ/2 mode. But the maximum output voltage of those samples appeared in λ/2 mode. In the PCT with partial both sided electrode, the ration of output voltage to input current was highest out of all samples and the poling voltage was a half times of 깬두 type transformer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.111-111
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• 2009

In this work, we discuss simulation of surface acoustic wave device using Comsol Multiphysics. The structure SAW device based on piezoelectric thin film aluminum-nitride (AlN) on silicon was simulated. Some parameters of SAW device such as surface velocity, displacement of piezoelectric thin film were evaluated by software. Many modes and shapes of wave are also discussed in this paper. For evaluation physical parameters of AlN piezoelectric layer, the SAW resonator was modeled and simulation results were also compared with experiment results. we simulated arid evaluated the surface Rayleigh wave of AlN thin film on silicon substrate. Results simulation and experiment showed the surface velocity of AlN thin film was about 5200 m/s and shape of surface wave was also displayed. This paper has also proposed as method to study SAW characteristic of piezoelectric thin film and found out measurement values accurately of film such as stiffness matrix, piezoelectric matrix. These values are very important in calculation and design SAW device or MEMS device based on AlN piezoelectric layer.