• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.347-351
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• 1997

A micromachined piezoelectic cantilever transducer,which works both as a microphone and as a microspeaker,has been fabricated and tested. The 2000*2000*3.mu.m .sap2. cantilever has oxide(ZnO)piezoelectric thin film on a supporting layer of low-pressure chemical-vapor-deposited(LPCVD)low-stress siliconnitride. A highlight of the fabrication process which may also be relevant for other micromachined stuctures is the technique for producing a flat,multilayer cantilever. The measured microphone sensitivity is fairly constant at 2 mV/.mu.bar in the low frequency range and rise to 20 mV/.mu.bar at the lowest resonant frequency of 890 Hz. The 2 mV/.mu.bar sensitivity is the highest report to data for a microphone with a micromachined diaphragm. When measured into a 2 cm/sap3 coupler with 4V (zero-park)drive,the microspeaker output sound pressure level(SPL) is 75 dB at 890 Hz. It increases to approximately 100dB SPL at 4.8kHz with 6V(zero-park)drive. The measured microphone frequency response agrees well with the results of an ABAQUS simulation.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.135-138
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• 2004

Conventional piezoelectric lead-zirconate-titanate (PZT) senor has high sensitivity, but it is very brittle. Recently polymer films such as polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride­trifluoroethylene) (P(VDF-TrFE)) copolymer have been used as a sensor. The advantages of polymer sensor are the flexibility and mechanical toughness. Simple process and possible several shapes are also additional advantages. Polymer sensor can be directly embedded in a structure. In this study, nondestructive damage sensitivity of single basalt fiber/epoxy composites was investigated with sensor type and thermal damage using AE and oscilloscope. And AE waveform for epoxy matrix with various damage types was compared to each other. The damage sensitivity of two polymer sensors was rather lower than that of PZT sensor. The damage sensitivity of PVDF sensor did not decrease until thermal damage temperature at $80^{\circ}C$ and they decreased significantly at $110^{\circ}C$ However, the damage sensitivity of P(VDF-TrFE) sensor at $110^{\circ}C$ was almost same in no damage sensor. For both top and side impacts, the difference in arrival time increased with increasing internal and surface damage density of epoxy matrix.

• Journal of Magnetics
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• 제16권3호
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• pp.271-275
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• 2011

This paper proposes a magnetoelectric (ME) composite transducer structure consisting of a magnetostrictive H-type Fe-Ni fork substrate and piezoelectric PZT plates. The fork composite structure has a higher ME voltage coefficient compared to other ME composite structures due to the higher quality (Q) factor. The ME sensitivity of the fork structure reaches 12 V/Oe (i.e., 150 V/cm Oe). The fork composite with two PZT plates electrically connected in series exhibits over 5 times higher ME voltage coefficient than the output of the rectangle structure in the same size. The experiment shows the composite of a Fe-Ni fork substrate and PZT plates has a significantly enhanced ME voltage coefficient and a higher ME sensitivity relative to the prior sandwiched composite laminates. By the use of a lock-in amplifier with 10 nV resolution, this transducer can detect a weak magnetic field of less than $10^{-12}$ T. This transducer can also be designed for a magnetoelectric energy harvester due to its passive high-efficiency ME energy conversion.

• 한국음향학회지
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• 제32권1호
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• pp.32-42
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• 2013

일반적인 수중 탐지용 압전 구형 센서는 무지향성이어서 스칼라 양인 수신 음압의 크기만 측정할 뿐 전파 방향은 측정 할 수 없는 한계를 가지고 있다. 본 논문에서는 이러한 구형 센서를 이용해 음파의 크기와 방향을 동시에 찾을 수 있는 방법을 제안한다. 제안한 방법은 구형 센서의 압전 세라믹을 8등분하여 배열한 다음, 각 압전 세라믹 출력전압을 특정한 방법으로 조합하여 음압의 크기와 방향을 파악할 수 있도록 하였다. 또한 압전세라믹 구의 반경과 두께와 같은 구조 변수들의 변화에 따른 감도 변화를 분석하여, 벡터 센서의 감도를 향상 시킬 수 있는 방안을 제시하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.5115-5118
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• 2015

Background: The $p16^{INK4a}$ is a protein that expressed in Liquid-based cervical cytology specimens and has been proved link to cervical cancer. The $p16^{INK4a}$ could be detection by piezoelectric immunosensor and the immobilization of the $p16^{INK4a}$ antibody influence the sensitivity of the piezoelectric immunosensor. Materials and Methods: $5{\mu}L$ mouse polyclonal antibody against $p16^{INK4a}$ was bound onto the surface of immonosensor through two methods. (directly immobilized method; protein A method). Absorb of the $p16^{INK4a}$ antibody on the surface of immonosensor caused a shift in the resonant frequency of the immunosensor and The frequency changes recorded showed a better reproducibility. The activity of the immobilization antibody with the directly method and protein A method was tested with $p16^{INK4a}$ antigen. Results: The resonant frequency for different antibody immobilization methods were different, and the sensitivity for $p16^{INK4a}$ detection also different. Conclusions: The protein A method was found to be much more better than the directly method for the immobilization of the p16INK4A antibody on the gold electrode of the quartz crystal for cervical lesion detection. The Protein A method created more reproducible and stable immobilization antibody layers with p16INK4A antigen.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.979-984
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• 2007

This paper presents a new control mechanism for the proportional pressure control which is accomplished by electro-pneumatic regulator using two PZT actuators. The electro-pneumatic regulator of this study is 2-stage type and consists of two piezoelectric actuators, a controller and a main poppet valve. The piezoelectric actuators are multilayer bender type and are controlled by digital signal. Proportional pressure control technique is very important because that can derive improvement of product quality and driving ability in the pneumatic system. Solenoid actuator method for pressure control is widely used but this actuator has a high power consumption characteristics. So new actuator is required for the energy saving. In this study, PZT actuator for the pressure control was fabricated and experimented instead of the conventional type solenoid actuator. Experiments for the new control mechanism of the elector-pneumatic regulator were operated under the input condition of 0.4[MPa] and it was confirmed that this mechanism has a good control characteristics to the response sensitivity and hysteresis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1994년도 추계학술대회논문집; 한국종합전시장, 18 Nov. 1994
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• pp.165-169
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• 1994

외팔보의 진동문제를 외란에 대한 감도최소화 문제로 공식화하여 현재 많이 개발되어 있는 H$_{\infty}$ 제어기법의 해를 이용하여 접근하고, 이의 성능을 비교하기 위하여 H$_{2}$ 공간에서의 특수한 문제인 LQG를 다루었다. 작동기는 압전소자를 사용하였고, 실제 항공익 등의 문제와 일치를 꾀하기 위하여 기반가진 형태의 외란을 가하였다. 모의 실험이 수행되었으며, 제시된 제어기가 많은 상황에서 좋은 성능을 가진다는 것이 밝혀졌다.

• 전자공학회논문지SC
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• 제43권4호
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• pp.30-34
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• 2006

외접형 초음파 유량센서용 압전 트랜스듀서의 송수신 특성을 개선하기 위하여 구성 부품의 재질 및 형상에 따른 특성 변화를 유한요소법으로 해석하였으며, 실제 실험을 통해 그 결과를 검증하였다. 두께모드 중심주파수가 1MHz가 되도록 직경 10mm의 압전소자를 제작하고, 매칭 레이어의 재질 및 구조 변화를 통하여 유량센서의 지향각을 $25^{\circ}$로 조절하였다. 이상의 결과를 통해 개발된 외접형 초음파 유량센서용 압전 트랜스듀서를 실제 산업용 배관에 적용 평가한 결과 기존 상엽용 센서에 비해 10배 이상의 감도를 나타내었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권4호
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• pp.293-298
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• 2006

Thermopiezoelectric method, using poly silicon heater and a piezoelectric sensor, was proposed for writing and reading in a probe based data storage system. Resistively heated tip writes data bits while scanning over a polymer media and piezoelectric sensor reads data bits from the self-generated charges induced by the deflection of the cantilever. 34${\times}$34 array of thermopiezoelectric nitride cantilevers were fabricated by a single step wafer level transfer method. We analyzed the noise level of the charge amplifier and measured the noise signal. With the sensor and the charge amplifier 20mn of deflection could be detected at a frequency of 10KHz. Reading signal was obtained from the cantilever array and the sensitivity was calculated.

• Journal of Magnetics
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• 제16권4호
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• pp.398-402
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• 2011

A novel laminate composite of FeCuNbSiB/FeNi /PZT is proposed, where FeCuNbSiB has a permeability of around 100000, which is much larger than that of FeNi. The high-permeability FeCuNbSiB was laminated with piezomagnetic FeNi rather than attached to its ends. It is expected that the effect produced by the high permeability will act on the whole of the piezomagnetic layer. While a FeNi layer was laminated with a FeCuNbSiB layer, the strong demagnetization produced by the latter was expected to be imposed on the FeNi layer as well as the applied fields. The distribution of applied fields was altered by the high-permeability material (both bias and ac field) and the field variation positively contributed to the ME effect in piezomagnetic/piezoelectric composites. Thus the ME voltage coefficient along with the field sensitivity were improved.