• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.680-683
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• 2011

This study deals with damage detection in beam structure by using modal strain energy-based technique with three different sensor types: accelerometer, lead zirconate titanate (PZT) piezoelectric sensor and electrical strain gage. First, the use of direct piezoelectric effect of PZT sensor for dynamic strain response are presented. Next, a modal strain energy-based damage detection method is outlined. For validation, forced vibration tests are carried out on lab-scale aluminum cantilever beam. The dynamic responses are measured for several damage scenarios. Based on damage localization results, the performance of three different sensor types is evaluated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.82.2-82.2
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• 2012

캐패시터, 액추에이터와 같이 MIM (Metal-Insulator-Metal) 구조를 갖는 디바이스는 높은 소결온도를 갖는 세라믹 유전체/압전체와 고온 내산화성이 낮은 금속 전극의 적층 형태로 인하여 동시 열처리 공정에 있어서 많은 제약이 따른다. 본 연구에서는 소결온도를 대폭 낮춘 저온 소결용 PZT 압전체 테이프를 니켈 금속 포일에 적층하여 동시 열처리를 통하여 소결을 시도하였다. 동시 열처리된 MIM 디바이스의 세라믹과 금속 전극 계면의 미세구조 및 성분 분석을 통하여 계면 반응 기구를 확인하였고, 계면 반응층이 디바이스의 특성에 미치는 영향에 대한 정량적 분석을 수행하였다. 또한 열처리 시간에 따른 계면 반응층의 변화를 관찰하고 반응층의 변화가 특성에 미치는 영향을 분석하였다. 니켈 이외에 니켈 합금인 INCONEL 718과 PZT 세라믹과의 동시 소성을 시도하여 니켈, INCONEL 두 금속 기판과 PZT 사이에 생성되는 계면 반응층의 미세구조와 특성의 차이점을 비교하였고 디바이스로서 사용하기 위한 적합성 여부를 확인하였다.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1069-1074
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• 1999

본 연구에서는 PbZr(sub)0.53Ti(sub)0.47O$_3$(PZT) 박막을 복수 도포함에 따른 박막내의 응력을 온도의 함수로 실시간(in situ) 측정하였으며, 응력발생의 원인에 박막의 건조, 열분해(pyrolysis), 치밀화 및 결정화 현상과 연관시켜 설명하였다. 도포직후 단층박막에 생성된 55MPa의 인장응력은 가열됨에 따라$ 300^{\circ}C$-$350^{\circ}C$에서 최대 145MPa로 증가하였으며, 박막내의 응력은 모든 온도구간에서 항상 인장응력을 나타내었더. 다층도포시 $650^{\circ}C$까지 열처리 주기를 완료한 층이 두꺼워질수록 새로 도포한 층의 영향은 점차 감소하였으며, 9층박막에 이르러서는 가열과 냉각에 따라 응력이 동일하게 변화하였다. 응력측정 결과 다층박막의 치밀화는 $350^{\circ}C$에서 시작되어 $520^{\circ}C$-$550^{\circ}C$ 부근에서 완료되는 것으로 나타났으며 치밀화가 시작하는 온도는 미세경도 측정결과와 일치하였다. $PbTiO_3$(PT)와 달리 PZT 다층박막은 Si 기판 위에서 perovskite로의 결정화가 일어나지 않았다.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1078-1084
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• 2002

The formation temperature for the perovskite lead zirconate titanate [Pb(Zr,Ti)O3, PZT] derived from sol-gel route was lowered by more than $100^{\circ}C$ with the addition of crystallographically suitable seed particles, such as barium titanat e (BT) or PZT. We investigated the effect of seeding on the crystallization of perovskite phase and in the microstructure of the sol-gel derived PZT powder by varying the concentration, size and chemical species of seed particles. The phase transition as a function of temperature was monitored by DTA, XRD, and Raman spectroscopy, and the interface between the seed particle and grown PZT layer was analyzed by SEM and high resolution TEM techniques. It was found that both the heterogeneous and homogeneous nucleation contributes competitively in the formation of perovskite PZT grains.

• Journal of the Korean Ceramic Society
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• v.28 no.12
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• pp.943-952
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• 1991

Lead zirconate titanate(PZT) powders and thin films were prepared from an alkoxide-based solution by sol-gel method. Gelation of synthesized complex solutions, pyrolysis and crystallization behaviors of the dried powder were studied in accordance with a water content and a catalyst. PZT thin films were formed by spin-casting method on silicon and platinum substrates, and characterized. Ester produced from the reactions was completely removed when drying of the gel was finished. Pyrolysis property of the dried PZT gels were changed in order water content, class of catalyst, and quantity of catalyst. Crystalline Pb phase was transiently formed near 250$^{\circ}C$. Basic catalyst is good additive for a formation of perovskite phase in the films, and acidic catalyst for a densified film structure. By the analysis of RBS, Pb element in the PZT films were diffused into silicon substrate, and the pores, may be produced due to local densification around some grains in the films, make an origin of fault in microstructure when holding time goes to be longer at 700$^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.55 no.1
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• pp.67-73
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• 2018

A poled lead zirconate titanate (PZT) cube specimen that is switched by an electric field at room temperature is subject to temperature increase. Changes in polarization and thermal expansion coefficients are measured during temperature rise. The measured data are analyzed to obtain changes in pyroelectric coefficient and strain during temperature change. Empirical formulae are developed using linear or quadratic curve fitting to the data. The nonlinear behavior of the materials during temperature increase is predicted using the developed formulae. It is shown that the calculation results can be compared successfully with the measured values, which proves the accuracy and reliability of the developed formulae for the nonlinear behavior of the materials during temperature changes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.50-53
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• 1988

Lead titanate powders were prepared by mixed-oxide and sol-gel method. O-3 composites were prepared with these powders using Eccogel polymer. According to the volume percent of the PbTiO$_3$ powders, dielectric, piezoelectric properties and poling conditions were investigated. Relative dielectric constants were exponentially increased with volume percent of PbTiO$_3$. Piezoelectric strain coefficients (d$_{33}$ ) were increased with volume percent of PbTiO$_3$. Figure of merit (d$_{h}$.g$_{h}$) for the O-3 composites prepared by the mixed-oxide and sol-gel method were 2728(x10$^{-15}$ $m^2$/N) and 3100(x10$^{-15}$ $m^2$/N) at 70 volume percent of PbTiO$_3$, respectively.ely.

• Smart Structures and Systems
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• v.17 no.6
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• pp.1055-1065
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• 2016

An anisotropic ultrasonic transducer is proposed for Lamb wave applications, such as passive damage or impact localization based on ultrasonic guided wave theory. This transducer is made from a PMNPT single crystal, and has different piezoelectric coefficients $d_{31}$ and $d_{32}$, which are the same for the conventional piezoelectric materials, such as Lead zirconate titanate (PZT). Different piezoelectric coefficients result in directionality of guided wave generated by this transducer, in other words, it is an anisotropic ultrasonic transducer. And thus, it has different sensitivity in comparison with conventional ultrasonic transducer. The anisotropic one can provide more information related to the direction when it is used as sensors. This paper first shows its detailed properties, including analytical formulae and finite elements simulations. Then, its application is described.

• Smart Structures and Systems
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• v.17 no.6
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• pp.881-901
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• 2016

In this study, a method to compensate the effect of temperature variation on impedance responses which are used for prestress-loss monitoring in prestressed concrete (PSC) girders is presented. Firstly, an impedance-based technique using a mountable lead-zirconate-titanate (PZT) interface is presented for prestress-loss monitoring in the local tendon-anchorage member. Secondly, a cross-correlation-based algorithm to compensate the effect of temperature variation in the impedance signatures is outlined. Thirdly, lab-scale experiments are performed on a PSC girder instrumented with a mountable PZT interface at the tendon-anchorage. A series of temperature variation and prestress-loss events are simulated for the lab-scale PSC girder. Finally, the feasibility of the proposed method is experimentally verified for prestress-loss monitoring in the PSC girder under temperature-varying conditions and prestress-loss events.

• Korean Journal of Materials Research
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• v.14 no.2
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• pp.115-120
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• 2004

Perovskite barium-strontium titanate, $(Ba, Sr)TiO_3$ was prepared and effects of $Sb_2$O$_3$ additives on its PTCR properties were investigated. $The (Ba,Sr)TiO_3$ with 0.05～0.25 mol% $Sb_2$$O_3$ showed semiconducting PTCR behavior and anomalous grain growth was also observed when it was sintered above $1330^{\circ}C$. It was considered that charge compensation by doping 8b203 as well as abnormal grain growth by sintering lead to resistivity reduction from insulating to semiconducting transition.