• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.144-149
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• 2000

The demands for robotic and automatic system are continually increasing in manufacturing fields. There have been many studies to monitor and predict the system, but they have mainly focused upon measuring cutting force, and current of motor spindle, and upon using acoustic sensor, etc. In this study, time series sequence of cutting force was acquired by taking advantage of piezoelectric type tool dynamometer. Radial cutting force was obtained from it and was available for useful observation data. The parameter was estimated using PAA(parameter adaptation algorithm) from observation data. ARMA(auto regressive moving average) model was selected for system model and second order was decided according to parameter estimation. Uncorrelation test was also carried out to verify convergence of parameter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.690-693
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• 2002

This paper is concerned on method of simultaneous force(stress) and temperature sensing with PVDF film. PVDF film has piezoelectric and pyroelectric properties. Therefore, it senses changes of stress and temperature. But it's output is affected with two properties. Using different medium in a sensing element, this problem is solved. Two structures induce different equations that its solutions are changes of stress and temperature. This method and result is applicable in skin sensor that has complexity of material and structure.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.40-45
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• 1999

The demands for robotic and automatic system are continually increasing in manufacturing fields. There have been many studies to monitor and predict the system, but they have mainly focused upon measuring cutting force, and current of motor spindle, and upon using acoustic sensor, etc.In this study, time series sequence of cutting force was acquired by taking advantage of piezoelectric type tool dynamometer. Radial cutting force was obtained from it and was available for useful observation data. The parameter was estimated using PAA (parameter adaptation algorithm) from observation data. ARMA(auto regressive moving average) model was selected for system model and second order was decided according to parameter estimation. Uncorrelation test was also carried out to verify convergence of parameter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.390-396
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• 2010

An 80MHz surface acoustic wave (SAW)-based gyroscope utilizing a progressive wave was developed on a piezoelectric substrate. The developed sensor consists of two SAW oscillators in which one is used for sensing element and has metallic dots in the cavity between input and output IDTs. The other is used for a reference element. Coupling of mode (COM) modeling was conducted to determine the optimal device parameters prior to fabrication. According to the simulation results, the device was fabricated and then measured on a rate table. When the device was subjected to an angular rotation, oscillation frequency differences between the two oscillators were observed because of the Coriolis force acting on the metallic dots. Depending on the angular rate, the difference of the oscillation frequency was modulated. The obtained sensitivity was approximately 52.35 Hz/deg.s within the angular rate range of 0~1000 deg/s. The performances of devices with three IDT structures for two kinds of piezoelectric substrates were characterized. Good thermal stability was also observed during the evaluation process.

• Journal of the Ergonomics Society of Korea
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• v.11 no.2
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• pp.23-33
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• 1992

The distribution of the pressure between the sole of a feet and a supporting surface can reveal the information about the structure and fonction of the foot and the posural control of the whole body. In particular, the measurement of the vertical contact forces between the plantar surface of the foot and the shoe insole is of great importance to reveal the loading distributio patterns incurred from a particular shoe midsole design. In order to investigate the plantar surface pressure distribution, an insole-type sensor with a piezoelectric material is developed and tested. The present paper describes a new method to completely reduce both the shear force and pyroelectric effects that are normally caused from piezoelectric materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.313-320
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• 2005

Stick-slip friction is one of the material removal mechanisms in tribology. It occurs when the static friction force is larger than the dynamic friction force, and make the friction curve fluctuated. In the friction monitoring of chemical mechanical polishing(CMP), the friction force also vibrates just as stick-slip friction. In this paper, an attempt to show the similarity between stick-slip friction and the friction of CMP was conducted. The prepared hard pa(IC1000/Suba400 stacked/sup TM/) and soft pad(Suba400/sup TM/) were tested with SiO₂ slurry. The friction force was measured by piezoelectric sensor. According to this experiment, it was shown that as the head and table velocity became faster, the stick-slip time shortened because of the change of real contact area. And, the gradient of stick-slip period as a function of head and table speed in soft pad was more precipitous than that of hard one. From these results, it seems that the fluctuating friction force in CMP is stick-slip friction caused by viscoelastic behavior of the pad and the change of real contact area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.983-989
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• 2005

The effects of mechanical parameters on the characteristics of chemical mechanical polishing(CMP) can be directly evaluated by friction force. The piezoelectric quartz sensor for friction force measurement was installed, and friction force could be detected during CMP process. Furthermore, friction energy can be calculated by multiplying relative velocity by integration of the friction force throughout the polishing time. $SiO_2$ slurry for interlayer dielectric(ILD) CMP was used in this experiment to consider the relation of frictional characteristics and polishing results. From this experiment, it is proven that the friction energy is an essential factor of removal rate. Also, the friction force is related to removal amount per unit length(dH/ds) and friction energy has corelation to the removal rate(dH/dt) and process temporature. Moreover, within wafer non-unifornity(WIWNU) is related to coefficient of friction because of the mechanical moment equilibrium. Therefore, the prediction of polishing result would be possible by measuring friction force.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.13-13
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• 2010

Piezoelectric sensors are extensively used to measure force because of their high sensitivity and low cost. however, the development of device with reduced size but with improved sensitivity is highly important. Low-temperature co-fired ceramic (LTCC) is one of promising materials for this application than a silicon substrate because it has very good electrical and mechanical properties as well as possibility of making various three dimensional (3D) structures. In this work, piezoelectric pressure sensors based on hybrid LTCC technology were presented. The LTCC diaphragms with thickness of $400\;{\mu}m$ were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The piezoelectric sensing layer consists of PZT thin film deposited by RF magnetron sputtering method on between top and bottom Au electrodes. The PZT films deposited on LTCC diaphragms were successfully grown and were analyzed by using X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM).

• Explosives and Blasting
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• v.35 no.3
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• pp.15-20
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• 2017

In order to obtain the dynamic response behavior of the rock subjected to blasting loading, a shock-proof high sensitivity impact sensor which can measure high frequency dynamic force and strain events should be adopted. Because the impact sensors which uses quartz and piezoelectric element are costly, generally the strain measurement-based impact (SMI) sensors are applied to high speed loading devices. In this study, dynamic Brazilian tension tests of granitic rocks was conducted using the Nonex Rock Cracker (NRC) reaction driven-high speed loading device which adopts SMI sensors. The dynamic response of the granite specimens were monitored and the intermediate strain rate dependency of Brazilian tensile strengths was discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.442-448
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• 2008

This paper presents an approach to define an optimal piezoactuator length to actively control structural vibration. The optimal ratio of the piezoactuator length against beam length when a pair of piezoceramic actuator and accelerometer is used to suppress unwanted vibration with direct velocity feedback (DVFB) control strategy is not clearly defined so far. It is well known that direct velocity feedback (DVFB) control can be very useful when a pair of sensor and actuator is collocated on structures with a high gain and excellent stability. It is considered that three different collocated pairs of piezoelectric actuators (20, 50 and 100 mm) and accelerometers installed on three identical clamped-clamped beams (300 * 20 * 1 mm). The response of each sensor-actuator pair requires strictly positive real (SPR) property to apply a high feedback gain. However the length of the piezoactuator affects SPR property of the sensor-actuator response. Intensive simulation and experiment shows the effect of the actuator length variation is strongly related with the frequency range of SPR property. A shorter actuator gave a wider SPR frequency range as a longer one had a narrower range. The shorter actuator showed limited control performance in spite of a higher gain was applied because the actuation force was relatively small. Thus an optimal length ratio (actuator length/beam length) was suggested to obtain relevant performance with good stability with DVFB strategy. The result of this investigation could give important information in the design of active control system to suppress unwanted vibration of smart structures with piezoelectric actuators and accelerometers.