• 한국소음진동공학회논문집
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• 제19권9호
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• pp.915-921
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• 2009

Cellulose based electro-active paper(EAPap) is considered as a new smart material which has a potential to be used for biomimetic actuators and sensors. Beside of the natural abundance, cellulose EAPap is fascinating with its biodegradability, lightweight, high mechanical strength and low actuation voltage. When the external stress is applied to EAPap, it can generate the electrical output due to its piezoelectric property. Using piezoelectric behavior of EAPap, we studied the feasibility of EAPap as mechanical strain sensor applications and compared to commercial strain sensor. By measuring the induced output voltage from the thin piezoelectric cellulose EAPap under static and dynamic force, we propose cellulose EAPap film as a potential strain sensor material.

• 한국전기전자재료학회논문지
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• 제25권4호
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• pp.286-289
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• 2012

In this paper, we have proposed piezoelectric energy harvester employing the pillar structure with the diameter size of 500 um. So we have selected the Su-8 photo-resist and modified lithography process to manufacture the pillar structure with height above the $500{\mu}m$. Simultaneously, we tried to make a comparative study to use ceramic bulk - polymer structure In this paper, we will report the process and properties of micro pillar structure based on the PMN-PZT ($Pb(Mg_{1/3}Nb_{2/3})O_3-PbZrTiO_3$) materials. Finally, We will propose a method for generating electrical energy with a piezoelectric element using vibration, an energy source can be obtained from the "clean" energy.

• Composites Research
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• 제35권3호
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• pp.134-138
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• 2022

본 연구에서는 기존 폴리머 콘크리트의 진동 감쇠 효과를 향상시키기 위해 압전 재료 중 하나인 PZT 파우더를 첨가하여 티타늄 파우더/폴리머 콘크리트 복합재료를 제작하였다. 티타늄 파우더는 압전 효과를 이용한 진동특성 변화를 극대화하기 위해 일정한 비율로 유지하였고, PZT 파우더를 첨가하지 않은 시편, PZT 파우더를 2.5 wt%, 5 wt% 첨가한 세 가지 종류의 복합재료 시편을 제작하였으며, 모든 시편에 대해 진동 특성 및 압축 물성 분석을 진행하였다. 그 결과, PZT 파우더 첨가 비율이 높아질수록 티타늄 파우더/폴리머 콘크리트에서 발생한 진동이 전달될 때 압전 효과로 인해 공진주파수에서 전달 함수 Inertance 값이 작아지는 것을 확인하였고, 특히 PZT 파우더 5 wt% 첨가 시편의 경우, 공진주파수에서 Inertance 값은 PZT가 첨가되지 않은 시편에 비해 약 19.3% 감소하는 것으로 나타났다. 시간에 따른 가속도 변화 폭 역시 PZT 파우더가 첨가됨에 따라 크게 감소하는 것으로 나타나 PZT 첨가에 따른 효과를 확인할 수 있었다. 또한, 압축강도 시험을 통해 5 wt%까지의 PZT 첨가에 의한 압축 물성 저하 정도는 미미한 것으로 나타났고, 시편 단면 분석을 통해 파우더가 고르게 분산된 것을 확인하였다.

• Smart Structures and Systems
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• 제13권4호
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• pp.567-585
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• 2014

The piezoelectric transverse $d_{15}$ shear sensing mechanism is firstly assessed experimentally for a cantilever smart sandwich plate made of a piezoceramic axially poled patched core and glass fiber reinforced polymer composite faces. Different electrical connections are tested for the assessment of the sensor performance under a varying amplitude harmonic (at 24 Hz) force. Also, the dynamic response of the smart sandwich composite structure is monitored using different acquisition devices. The obtained experimentally sensed voltages are compared to those resulting from the benchmark three-dimensional piezoelectric coupled finite element simulations using a commercial code where realistic features, like equipotential conditions on the patches' electrodes and mechanical updating of the clamp, are considered. Numerically, it is found that the stiffness of the clamp, which is much softer than the ideal one, has an enormous influence on the sensed voltage of its adjacent patch; therefore, sensing with the patch on the free side would be more advantageous for a cantilever configuration. Apart from confirming the latter result, the plate benchmark experimental assessment showed that the parallel connection of its two oppositely poled patches has a moderate performance but better than the clamp side patch acting as an individual sensor.

• Smart Structures and Systems
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• 제9권6호
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• pp.535-547
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• 2012

Controlling the balance of motion in a context involving a biped robot navigating a rugged surface or a step is a difficult task. In the present study, a $3{\times}5$ flexible piezoelectric tactile sensor array is developed to provide a foot pressure map and zero moment point for a biped robot. We introduce an innovative concept involving structural electrodes on a piezoelectric film in order to improve the sensitivity. The tactile sensor consists of a polymer piezoelectric film, PVDF, between two patterned flexible print circuit substrates (FPC). Additionally, a silicon rubber bump-like structure is attached to the FPC and covered by a polydimethylsiloxane (PDMS) layer. Experimental results show that the output signal of the sensor exhibits a linear behavior within 0.2 N ~ 9 N, while its sensitivity is approximately 42 mV/N. According to the characteristic of the tactile sensor, the readout module is designed for an in-situ display of the pressure magnitudes and distribution within $3{\times}5$ taxels. Furthermore, the trajectory of the zero moment point (ZMP) can also be calculated by this program. Consequently, our tactile sensor module can provide the pressure map and ZMP information to the in-situ feedback to control the balance of moment for a biped robot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.341-344
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• 1989

A Modified equivalent circuit by combining a series and parallel of polymer matrix for estimating the dielectric constant ${\bar{K}}_{33}$ values changing the volume percent of $PbTiO_3$, the dependences of frequency for the 713 and dissipation factor for 0 - 3 composites was derived. The difference of the dielectric constant and dissipation factor between the calculated and measured values became smaller at higher volume percent of $PbTiO_3$. There was, good agreement between the calculated and observed results for 70 volume percent of $PbTiO_3$ and 30 volume percent of Eccogel composite at 1(KHz), 25($^{\circ}C$). The optimized variable x was 0.94 in $PbTiO_3$ ceramics. $PbTiO_3$ powder and Eccogel polymer were used as piezoelectric fillers and matrix, respectively.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.216-219
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• 2002

Conventional piezoelectric lead-zirconate-titanate (PZT) senor has high sensitivity, but it is very brittle. Recently polymer films such as polyvinylidene fluoride (PVDF) have been used use as a sensor. The advantages of PVDF are the flexibility and mechanical toughness. Simple process and possible several shapes are also additional advantages. PVDF sensor can be directly embedded and attached to a structure. In this study, PVDF sensor was embedded in single glass fiber/epoxy composites whereas PZT sensor with AE was attached to single fiber composites (SFC). Piezoelectric sensor responds to interfacial damage of SFC. The signals measured by PVDF sensor were compared to PZT sensor. PZT sensor detected the signals of fiber fracture, matrix crack, interfacial debonding and even sensor delamination, whereas PVDF sensor only detected fiber fracture signals so far, because PZT sensor is much more sensitive than current PVDF sensor. Wave voltage of fiber fracture measured by PVDF sensor was lower than that of PZT sensor, but the results of fast Fourier transform (FFT) analysis were same. Wave velocity using two PZT sensors was also studied to know the internal and surface damage effect of epoxy specimens.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
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• pp.103.1-103
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• 2003

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.145-146
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• 2008

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 추계총회 및 연구발표회 초록집
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• pp.94.2-94
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• 2003