• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.477-485
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• 2010

Various monitoring sensors are used to predict and detect structural damage. Smart sensors, such as glass-fiber sensors, PZT, and MEMS, among others, have replaced traditional sensors. They are now being used in many areas. This study aims to predict the damage by measuring the PZT voltage attached on the specimen by the applied impact load. In the experiment to detect damages in beam connection, simple $H-400{\times}200{\times}8{\times}13$ beams were spliced with bolts. The results of FFT between PZT sensor and accelrometer were compared to measure the sensitivity of the PZT sensor. The damage to the beam was presumed by loosening the bolt, and then the damage measurement was accompanied. Secondly, a steel $PL600{\times}65{\times}5.8$ plate beam was fabricated for the purpose of experimenting on damage measurement. Impact loading test on three different locations was carried out. Damage width varied between 6~42mm on both sides by cutting, using a steel saw. The ratio of frequencies before and after the damage was computed to quantify the damage level by using FFT, and the change in mode pattern with the increased damage was investigated to measure the damage.

• Composites Research
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• v.17 no.4
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• pp.61-67
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• 2004

Nondestructive damage sensitivity on single-basalt fiber/epoxy composites was evaluated by micromechanical technique and acoustic emission (AE). Piezoelectric lead-zirconate-titanate (PZT), polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer were used as AE sensor, respectively. In single-fiber composite, the damage sensing with different sensor types were compared to each other. Piezoelectric PVDF polymer sensor was embedded in and attached on the composite, whereas PZT sensor was only attached on the surface of specimen. In case of embedded polymer sensors, responding sensitivity was higher than that of the attached case. It can be due to full constraint inside specimen to transfer elastic wave coming from micro-deformation. For both the attached and the embedded cases, the sensitivity of P(VDF-TrFE) sensor was almost same as that of conventional PVDF sensor.

• Proceedings of the Acoustical Society of Korea Conference
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• 1996.10a
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• pp.35-41
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• 1996

본 연구에서는 PZT를 이용한 Bimorph Cantilever형 진동센서의 동특성을 모달해석하고 이를 압전세라믹의 센서방정식과 연계하여 센서출력의 정밀해를 구하였다. 그리고 이론식에 대한 시간응답 특성 및 주파수응답 특성을 알아보고 각각의 특성을 만족시키기 위한 센서의 최적설계 기법을 컴퓨터 Simulation을 통하여 알아보았다. 그리고 PZT를 이용한 Bimorph Cantilever형 진동센서를 직접 제작하고 그 실험적 데이터를 수식적 데이터와 비교하여 이론식의 타당성을 검증하였다.

• Journal of Sensor Science and Technology
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• v.10 no.3
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• pp.173-179
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• 2001

The currently used semiconductor pressure sensors are piezoresistive and capacitive type. Especially, semiconductor micro pressure sensors have a great deal of attention because of their small size. However, its fabrication processes are difficult, so that its yield is poor. For the purpose of resolving the drawbacks of the existing silicon pressure sensors, we demonstrate a new type of pressure sensor using PSFET(pressure sensitive field effect transistor) and investigate its operational characteristics. We used PZT(Pb(Zr,Ti)$O_3$) as a pressure sensing material. PZT thin films were deposited on a gate oxide of MOSFET by an rf-magnetron sputtering method. To abtain the stable phase, perovskite structure, furnace annealing technique have been employed in PbO ambient. The sensitivity of the PSFET was 0.38 mV/mmHg.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.72-78
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• 2010

A CFRP (Carbon Fiber-Reinforced Plastic) strengthening method is being very widely used to increase the load-carrying capacity of host structures, especially for bridges. However, not only flexure and shear failures but debonding failure also might occur in CFRP strengthened concrete structures. The CFRP debonding failure would cause a collapse accident of the host structure. Therefore, real-time health monitoring about the CFRP bonding condition is strongly required. In this study, a feasibility of the impedance-based damage detection method using PZT sensors is investigated through a series of experimental study monitoring both concrete cracks and CFRP debonding defects.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.367-369
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• 2009

본 논문은 저전력 무선 임피던스 기반 구조물 건전성 감시 USN 시스템을 활용하여 electro-mechanical Impedance 센서의 일종인 PZT센서를 부착한 배관 구조물의 건전성을 진단하는 방법과 그 실험 결과에 대해 소개 한다. 기존에는 건설구조물에 가해지는 전기적인 입출력비에 해당하는 임피던스를 계측하기 위해서 비교적 고가의 대형 계측 장비가 필요로 했으며, 구조물에 설치된 센서를 계측장비에 연결하기 위한 유선의 케이블 작업 역시 추가로 필요했었다. 대형 배관 구조물의 경우에는 이러한 문제점 때문에 임피던스를 이용한 능동형 센서가 제대로 활용되지 못하고 있고 비정기적인 비파괴검사에만 국한되어 사용되어 왔다. USN기술은 저전력 소출력 무선통신을 통해 기존의 계측시스템과는 다른 상시모니터링의 장점을 가지고 있는 기술로서 최근 토목/건설 분야에서 적극적으로 활용이 되는 융합기술이다. 본 논문에서 구조물 건전성 감시 분야와 저전력 무선 계측 기술의 통합을 통해 얻어진 최적화된 배관 건전도 진단 센서 노드의 효율성을 정량적 실험 데이터를 통해 입증하고, 앞으로의 연구 방향에 대한 제안으로 끝을 맺는다.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.202-208
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• 2010

This study examined the dependency of crystalline orientation and electric properties of sol-gel PZT film on hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The PZT thin films were prepared by using 2-Methoxyethanol-based sol-gel method and spin-coating on Pt/Ti/$SiO_2$/Si substrates. The 1-${\mu}m$-thick PZT films were coated and then fired in a furnace by direct insert method. The highly (111) oriented PZT film of pure perovskite structure could be obtained. We could control the degree of orientation by various parameters such as hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The highest measured remanent polarization, dielectric constant and piezoelectric coefficient are $24.16\;{\mu}C/cm^2$, 2808, and 159 pC/N, respectively.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.1-9
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• 1999

A study has been made on the fabrication of a dual mode(a longitudinal and shear mode) ultrasonic sensor using a single PZT piezoelectric ceramic element. We investigated the mechanism of the dual mode sensor that generated both of the longitudinal and the shear waves simultaneously with the single PZT element. Through the analysis of analytic wave propagation equations, all the possible crystal cuts have been examined to determine appropriate Euler transformation angles for efficient excitations of the dual modes. We studied the performance of a PZT element as a function of its rotation angle so that its efficiency is optimized to excite the two waves of equal strength. Experimental examination of the waveform on a delay line(STS303) setup confirms that the ultrasonic sensor can transmit and detect both longitudinal and shear waves simultaneously.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.58-63
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• 2019

This research aims at designing a diaphragm made of SUS316L stainless steel for ultra high pressure sensors and evaluating its performance with a PZT driven deformation tester instead of high pressure chamber testing up to 100 MPa. Finite element method analysis indicates that the optimum thickness of a flat diaphragm is 1.5 mm not only to secure safety of sensors up to 100 MPa but also to enhance displacement measuring sensitivity. For this thickness, the maximum displacement at the center of the diaphragm is $5.3{\mu}m$. The PZT actuator must offer a force of 1,669 N to create a pressure of 100 MPa at the diaphragm surface in order to obtain a displacement of $5.3{\mu}m$. The performance evaluation by the PZT driven tester demonstrates nearly the same results as the same results as the sensors tested in the ultra high pressure chamber.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.246-247
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• 2000

최근에 개발된 광섬유 격자소자(FBG)를 이용한 광섬유 수중 음향센서는 기존의 광섬유 센서가 지니고 있는 우수한 장점들을 지니고 있을 뿐만 아니라, PZT센서가 검출할수 없는 저주파수(30Hz∼300Hz)특성에서도 우수한 신호 감지효과를 지니고 있으며, 특히 군사용으로 사용될 수 있는 저주파 신호 검출에 실용화를 기대 할수 있으며, 센서 어레이(array)를 통하여 고감도 다중화로 발전될 수 있다.