• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1179-1183
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• 2007

Electro-Active paper(EAPap) is a new smart material that has a potential to be used in biomimetic actuator and sensor. It is made by cellulose that is abundant material in nature. EAPap is fascinating with its biodegradability, lightweight, large displacement, high mechanical strength and low actuation voltage. Actuating mechanism of EAPap is known to be the combined effects of ion migration and piezoelectricity. However, the electromechanical actuation mechanisms are not yet to be established. This paper presents the modeling of the actuation behavior of water infused cellulose samples and their composite dielectric constants calculated by Maxwell-Wagner theory. Electro-mechanical forces were calculated using Maxwell stress tensor method. Bending deflection was evaluated from simple beam model and compared with experimental observation, and which result in good correlation with each other.

• Journal of Sensor Science and Technology
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• v.20 no.1
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• pp.58-63
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• 2011

A low loss radio frequency(RF) micro electro mechanical systems(MEMS) switch driven by a low actuation voltage was designed for the development of a new RF MEMS switch. The RF MEMS switch should be encapsulated. The glass cap and fabricated RF MEMS switch were assembled by the Au/Sn eutectic bonding principle for wafer-level packaging. The through-vias on the glass substrate was made by the glass dry etching and Au electroplating process. The packaged RF MEMS switch had an actuation voltage of 12.5 V, an insertion loss below 0.25 dB, a return loss above 16.6 dB, and an isolation value above 41.4 dB at 6 GHz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.275-278
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• 2004

Electro-Active Paper (EAPap) is attractive for EAP actuator due to its merit in terms of light weight, dry condition, large displacement output, low actuation voltage and low power consumption. The EAPap is based on cellulose paper, and is shown to involve primarily transport of ions in response to an external electric field. This actuating mechanism is similar to conductive polymer based actuators. For performance improvement of EAPap, hybrid actuators are tried. The actuators based on cellulose paper attached conducting polypyrrole, polyaniline and single wall carbon nanotube/polyaniline(emeraldine base) have been achieved by Electro chemical deposition and mechanical deposition of the polymers onto cellulose paper.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.225-230
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• 2013

This paper presents a novel shunt radio frequency microelectromechanical system switch on a quartz substrate with stiff ribs around the membrane. The buckling effects in the switch membrane and stiction problem are the primary concerns with RF MEMS switches. These effects can be reduced by the proposed design approach due to the stiffness of the ribs around the membrane. A lower mass of the beam and a reduction in the squeeze film damping is achieved due to the slots and holes in the membrane, which further aid in attaining high switching speeds. The proposed switch is optimized to operate in the k-band, which results in a high isolation of -40 dB and low insertion loss of -0.047 dB at 21 GHz, with a low actuation voltage of only 14.6 V needed for the operation the switch. The membrane does not bend with this membrane design approach. Finite element modeling is used to analyze the stress and pull-in voltage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.1-6
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• 2008

This paper presents muscle-inspired serial digital actuators, achieving the improvement of the range-to-precision and range-to-voltage performance. We propose a weight-balanced design for the serial actuators with serpentine springs using serial arrangement of digital actuators. We have measured the displacement range, precision, and drive voltage at unit and serial actuation of 1Hz. The serial digital actuators produce a full range displacement of $28.44{\pm}0.02{\mu}m$, accumulating the unit displacement of $2.8{\pm}0.5{\mu}m$ at the operating voltage of $4.47{\pm}0.07V$. In addition, the serial digital actuators having the displacement precision of $37.94{\pm}6.26nm$ do not accumulate the precision of the unit actuators, $36.0{\pm}17.7nm$. We experimentally verify that the serial digital actuators achieve the range-to-squared-voltage ratio of $1.423{\mu}m/V^2$ and the range-to-precision ratio of 749.6.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.12
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• pp.601-607
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• 2002

IPMC(Ionic Polymer Metal Composite)actuators were optimized for producing improved forces by changing multiple parameters including repetition of number of plating, surface electroding and additive(PVP)-treatment on reduction. The platinum electrode is deposited on the surface of the material where platinum particle stay in a dense form that appears to introduce a significant level of surface electrode resistance. Actuation tests were performed for such IPMC actuators under a low voltage. The test results show that the lower surface-electrode resistance generates higher actuation capability in the IPMC actuators. In order to investigate relaxation behavior of bending and repeatability in dry condition, the IPMC was coated by$rubber(KRATON^{TM})$to minimize the effect of water evaporation from IPMC. This actuator can be used in air with surface coating to avoid membrane drying.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1521-1527
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• 2000

A micromirror actuated by piezoelectric unimorph cantilevers is proposed as a tine-tracking device for high-density optical data storage. Bending motions of the metal/PZT/metal unimorphs translate an integrated micromirror along the out-of-plane vertical direction. The micromirror alters the optical path of the incident laser beam and linearly steers the reflected laser beam by its out-of-plane parallel actuation. Numerical analysis shows that the actuated micromirror can satisfy the tracking speed imposed by the requirement on the access time for the high-density optical data storage up to few tens Gbitlin2 owing to the light mass of the micromirror. In this paper, preliminary characteristics of the micro-machined PZT actuated micromirror (PAM) are reported. Only a 360 nm-thick PZT film deposited by sol-gel process shows both good electrical and mechanical characteristics for the fine-tracking actuator. The micromirror can be easily actuated up to several micrometers under low voltage operation condition well below 10 volts.

• Journal of Power Electronics
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• v.18 no.3
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• pp.871-878
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• 2018

In this paper, the conducted EMI reduction performances of active feed-forward current-sensing current-actuation (CSCA) and voltage-sensing current-actuation (VSCA) filters for a three-phase induction motor drive system are evaluated by experiments. For comparison purposes, the conducted EMI (CM emission, DM emission and total emission) of a three-phase induction motor drive with a conventional CM choke, a conventional CM choke in series with an active VSCA filter, and an active CSCA filter (where the CM choke was modified and used as a sensing current transformer) were compared to the case of a system without any filter inserted. Experimental results show that the active CSCA and VSCA filters can improve the CM reduction performance of the conventional CM choke by about 5 dB especially at low-frequencies. However, for DM comparisons, it shows that there is no different between cases with and without filters inserted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1387-1390
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• 2006

Several actuation mechanism for carton nanotubes has teen reported recently, including actuation by double-layer charge injection and ac voltages applyied to multiple electrodes. Carbon nanotube actuator based on double layer charge injection work well in electrolyte at low voltage. AC dielectrophoresis based on four electrode geometry demonstrated carton nanotubes in solution phase can be oriently manipulated by dielectrophoresis. From this point of view, and in regard to their performance, bucky paper actuator may alternate natural muscle. also, applied AC signal with appropriate magnitude and frequency together with four electrode arrangement has potential to realize nanotube electrokinetics.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.286-289
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• 2004

This paper presents the fatigue characteristics of LIPCA (LIghtweight Piezo-Composite Actuator) device system. The LIPCA device system is composed of a piezoelectric ceramic layer and fiber reinforced lightweight composite layers. Typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (coefficient of thermal expansion) and base layers with high CTE. The advantages of the LIPCA design are weight reduction by using the lightweight fiber reinforced plastic layers without compromising the generation of high force and large displacement and design flexibility by selecting the fiber direction and the size of prepreg layers. To predict the degradation of actuation performance of LIPCA due to fatigue, the cyclic electric loading tests using PZT specimens were performed and the strain for a given excitation voltage was measured during the test. The results from the PZT fatigue test were implemented into CLPT (Classical Laminated Plate Theory) model to predict the degradation of LIPCA's actuation displacement. The fatigue characteristic of PZT was measured using a test system composed of a supporting jig, a high voltage power supplier, data acquisition board, PC, and evaluated.