• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.203-204
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• 2008

Bacterial Cellulose Actuator with biocompatible and biodegradable properties was newly developed as an electro-active biopolymer under water. The performance of the BC actuator was improved through Li treatment. The mechanical and chemical properties of BC membranes were measured such as the tensile test, proton conductivity. The surface morphology of the bacterial cellulose was observed by using SEM. The electromechanical bending responses under both direct current and alternating current excitations were investigated. In voltage-current test,the power consumption under dynamic excitation increases with increasing voltage. Present results show that the bacterial cellulose actuator can be a promising smart material and may possibly have diverse applications under water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.569-573
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• 2004

RAINBOW(Reduced And Internally Biased Oxide Wafers) are a new class of high-displacement, piezoelectric actuator produced by selectively removing oxygen from one surface of ceramic using a high-temperature chemical reduction process. In this paper, RAINBOW composition of 0.4Pb$(Ni_{1/3}Nb_{2/3})O_3-0.6Pb(Zr_xTi_{1-x})O_3$ were prepared. Its dielectric and piezoelectric properties were investigated in the vicinity of MPB. The strain - electric field characteristics of RAINBOW actuator were significantly improved comparison with the conventional bulk actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.496-503
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• 2001

The suspension of the optical pickup actuator is damped by the presence of silicone rubber damper bond at its termination. In spite of the presence of it, the actuator still exhibits a strong mechanical resonance which affects its settling time and vibrational characteristics. This resonance can cause errors in reading information from the disk, particularly in high speed CD-ROM and DVD-ROM drives. Ferrofluids are stable colloidal suspensions of sub-micron sized magnetic particles in a carrier liquid. In the actuator design, ferrofluid is applied to the surface of the magnets until the quantity is sufficient to maintain intimate contact with the bobbin/carrier assembly. The fluid is retained in the magnetic field and its viscosity provides the desired mechanical damping to the moving assembly, improving the actuators settling time and vibrational characteristics. Access time is also improved, particularly on warped or eccentric discs.

• Smart Structures and Systems
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• v.11 no.6
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• pp.605-621
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• 2013

The paper deals with the design of a device for sound reproduction to be fixed to a supporting surface. The device is made up of two different types of acoustic actuators based on different technologies. This allows to reproduce sound in the range of frequencies from 20 Hz to 20 kHz. The generation of sound at high frequencies is demanded to a magnetostrictive actuator, while a more traditional magnetodynamics actuator is used to generate sound at low frequencies. The coupling between these two actuators leads to a device having small overall dimensions and high performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.687-694
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• 1997

The anisotropy and shape of distributed piezopolymer actuator have advantages over isotropic piezo ceramic materials, since these features of PVDF can be utilized as another design variable in control application. This study is interested in the reduction of sound transmission through elastic plate into interior space by using the PVDF actuator. The plate-cavity system is adopted as a test problem. The vibration of composite plate and the sound fields through plate are analyzed by using the coupled finite element and boundary element method. Some numerical simulations are performed on sound transmission through elastic plates. To investigate the effects of anisotropy and shape of distributed piezopolymer actuator, various kinds of distributed PVDF actuators are applied in sound control simulation for isotropic and anisotropic plates. The PVDF actuators applied are different from each other in their shapes and laminate angles. The results of control simulation show that the control effectiveness of distributed PYDF actuator can be enhanced by using the coupling between shape of actuator and vibration modes of structure and the anisotropy of piezoelectric properties of PVDF.

• International Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.1-8
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• 2016

The improvements in high performance and agility of modern fighter aircraft have led to improvements in survivability as well. Related to these performance increases are rapid response and adequate deflection of the control surfaces. Most control surface failures result from the failure of the actuator. Therefore, the failure and behavior of the actuators are essential to both combat aircraft survivability and maneuverability. In this study, we investigate the effects of flaperon actuator failure on flight maneuvers of a supersonic aircraft. The flight maneuvers were analyzed using six degrees of freedom (6DOF) simulations. This research will contribute to improvements in the reconfiguration of control surfaces and control allocation in flight control algorithms. This paper compares the results of these 6DOF simulations with the horizontal tail actuator failures analyzed previously.

• International Journal of Safety
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• v.8 no.1
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• pp.6-9
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• 2009

The crack in a J85 engine V.G. actuator arm shaft for a bell crank on the engine compressor was investigated. The crack was observed in twenty two shafts during the inspection of 238 shafts. The failure analysis of shaft cracks was performed by chemical composition analysis using ICP(Inductively Coupled Plasma) and by fracture surface and microstructure analysis using FE-SEM and optical microscope. The crack initiated from the top and bottom and propagated to the center along the grain boundaries. From the chemical composition analysis, the fractography of the fracture surface and the microstructure, it was found that the failure mechanism of the shafts is the inclusion-related intergranular decohesion crack. The inclusion was found out from MnS particle by EDS(Energy Dispersive Spectroscopy). The crack initiated MnS inclusion in the grain boundary and propagated with the increase of applied shear stress during long operation. In order to prevent the fracture, NDI(Nondestructive inspection) is needed periodically as recommended.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1334-1338
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• 2005

A limit switch box is used for an indicator of a valve actuator. This device indicates an opening and closing of a valve or a throttle in the valve actuator. In a ship, equipments require safety and robustness because of a rough environment and a specific condition during a voyage. However, the limit switch box has been used in an indoor environment generally. This study developed a new limit switch box which can be used at an outdoor environment. This study designed the new limit switch box. The housing of the limit switch box was made by an aluminum die cast method with surface painting after anodizing or chromate coating. In order to evaluate the endurance of the housing, the endurance tests against salt water have been conducted. Experiment results showed that the proposed device provides a reliable performance against salt water.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.61-67
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• 2002

In this study a control surface/actuator fault detection, identification, and accommodation system for aircraft is designed. This fault tolerant control system tries to return aircraft to its stable trim condition in a short time. The control system is designed using neural networks with Extended Back Propagation Algorithm which shows fast convergence. F-4 aircraft with possible stabilator or aileron failure/stuck is simulated with the proposed scheme.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.151-157
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• 2003

A new type of precision actuator is developed using piezoelectric bimorphs. This type of actuator is applicable for the flat surface or in-pipe system and can make forward and backward motion. Two bimorphs are linked serially and two different phased voltages are applied to each bimorph. Therefore, The end of the bimorph makes ellipsoidal motion. The device moves by the friction force between the rubber attached at the bimorph end and the inner surface of the pipe. As the results, the driving range of the device is about 0~18Hz and the device guarantees very high linearity at low frequency, 0~1 Hz. The maximum velocity of the device is about 6mm/s at 10Hz. The developed mechanism is very simple and use piezoelectric bimorph. So, it is possible to miniaturize and educe the power consumption.