• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.165-168
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• 1997

We have constructed a scanning confocal microscope using a 780 nm semiconductor laser, an actuator of a compact disk player and a quad-detector. This device detects heights and characteristics of a surface. The laser focus was located at the surface of a sample by using the error signal obtained by a quad-dector, and the current supplied to the actuator for lens was displayed as a height. The materials of a surface were classified according to reflected total intensities and was displayed by different color in a monitor. The device has very samll dimensions of 30 mm$\times$20 mm$\times$20 mm and scan field is 1.6 mm$\times$1.6mm. We obtained two images, one using only reflected light and the other using an error signal from a quad-detector and compared these two images.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.663-670
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• 2003

As the micro-technologies in the high precision manufacturing processes are developed, the demand for micro actuating device is increasing. But, it is difficult to achieve high resolution and wide operating range simultaneously with the conventional actuating systems which are contacting and type of dual servo system. So, the contact-free surface actuators whose movers are suspended or levitated were proposed. These systems can be applied to high precision stages and alignment apparatuses. The suspended mover can be assumed to be rigid body, but the mover is a structure in this study, therefore the vibration caused during the operating process has a serious adverse effect on the performance and it is very important to identify the vibrational characteristics. In this paper, a contact-free surface actuator is modeled in finite element method and updated by using the experimental modal data. Finally, the static and dynamic characteristics of the finite element model are predicted and then discussed.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.527-532
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• 2005

Ionic polymer metal composites (IPMC) are soft polymeric smart materials having large displacement at low voltage in air and water. The polymeric electrolyte actuator consists of a thin and porous membrane and metal electrodes plated on both faces, in impregnation electro-plating method. The response and actuation of actuator are governed. Among many factors governing the activation and response of IPMC actuator, the surface electrode plays an important role. In this study, the well-designed modification of electrode surface was carried out in order to improve the chemical stability well as electromechanical characteristics of the IPMC actuator. We employed Ion Beam Assisted Deposition (IBAD) method to prepare the topologically homogeneous thin surface electrode. After roughing the surface of Nafion membrane in order to get a larger surface area, the IPMC was prepared by impregnation for electro-plating and re- coating on the surface through traditional chemical deposition, followed by an additional surface treatment with high conductive metals with IBAD. It was observed that our IPMC specimen shows the enhanced surface electrical properties as well as the improved actuation and response characteristics under applied electric field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.478-485
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• 2001

A dynamic load simulator(DLS) which can reproduce on-ground the aerodynamic hinge moment of control surface is an essential rig for the performance and stability test of aircraft actuation system. By setting up load actuator as counter acting with the control surface driving actuator and designing an appropriate force control system for load actuator, DLS can be mechanized. Obtaining an accurate mathematical model for the DLS is the first step to successfully design an aerodynamic load replicati on system. Two theoretical models are presented and tested for their validities with the experimental results, which turns out to be not successful. An alternative way of using system identification approaches in investigated to develop a good nominal model for DLS dynamics, and suitable uncertainty bounds for this nominal model are proposed with the consideration of experimental results.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.579-584
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• 2003

Solenoid type magnetic actuator is the device, which could translate the electromagnetic energy to mechanical force. The force generated by magnetic flux, could be calculated by Maxwell stress tensor method. Maxwell stress tensor method is influenced by the magnetic flux path. Thus, magnetic force could be improved by modification of the iron case, which is the route of the magnetic flux. Modified design is obtained by parameter optimization using by Response surface methodology.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.40.2-40
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• 2002

This paper presents the reconfigurable flight controller in the presence of jammed actuator fault using the adaptive sliding mode control scheme. It is developed under the assumption that the control surface fault cannot be detected and the positions of stuck control surfaces are unknown. It is well known that sliding mode controller shows good performance for the systems with various uncertainties. None-operating stuck actuator makes the system behave like bias which degrades the system performance and sometimes destabilizes the system. Therefore, the bias term generated by actuator faults has to be compensated by the control system. To the objective, we adopt the adaptive sliding mode cont...

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1010-1014
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• 2002

A new type actuator has been designed and investigated to overcome thermal problems in slim optical disc drive which is adopted in mobile storage devices. Recently, in optical storage device technical trends, the size of optical disc drives is slimmer to adopt notebook computer and the spindle rotate velocity is faster to achieve high transfer rate and the power of actuator is higher to perform tilting, etc. However, these trends of optical disc drives tend to raise the environment temperature of drives, actuator power and parts temperature. Moreover, it is more difficult to remove the heat inside a drive and the temperature of an actuator increases and drive slims. As a result, increase of surface temperature of actuator body caused that second resonance of an actuator moves down to a lower frequency band and the performance of optical parts also deteriorates. Especially objective lens, coil and magnet of the actuator parts are easily damaged. To manage these thermal problems, in this paper an actuator with a hybrid blade, which is composed of vectra which has low thermal conductivity and magnesium which has high thermal conductivity, has been suggested and verified. Despite the high temperature environment, the proposed actuator showed good dynamic performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.11-12
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• 2006

Actuator arm of HDD were machined with the slitting saw of tungsten carbide to clarify the cutting characteristics in terms of the roughness of machined surface, the burr size and the tool wear. An improved performance in all view of the surface machined, the tool life and the cutting efficiency was obtained at the cutting speed of 4,000rpm with the feed of 300m/min. The tool life increases with increasing the t/T value, whereas surface roughness decreases. The tool with alternate type of B and C edges has an effect to decrease the burr size.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.76-83
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• 2003

To cope with stringent performance targets requested in many fields spanning the whole range of industry, the driver is necessary to realize large dynamic range as well as nano resolution, manipulate the mover orientation without additional driver, and be suitable for clean environment. As one of those purposes, authors have developed the planar precision stages with the integrated operating principle of levitation and propel. In this paper, we discuss potential of magnetic suspension technology by comparing various features of non-contact planar stages, that is, repulsive type of surface actuator and attractive type of surface actuator.

• Journal of KSNVE
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• v.5 no.3
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• pp.313-325
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• 1995

Two active/passive vibration dampers were designed to control a cantilever beam first mode of vibration. The active element was a piezoelectric polymer, polyvinlidene fluoride (PVDF). The passive damping was provided by the application of a viscoelastic layer on the surface of the steel beam. Two substantially different damper configurations were designed and tested. One damper consisted of a piezoelectric actuator bonded to one face of the beam, with a viscoelastic layer applied to the other surface of the beam. The second one was composed of a layer viscoeastic layer with one surface bonded to the beam, and with other being constrained by nine piezoelectric actuators connected in parallel. A control law based on the sign of the angular velocity of the cantilever beam was implemented to control the beam first mode of vibration. The piezoelectric sensor output was digitally differentiated to obtain the transverse linear velocity, and its sign was used in the control algorith. Two dampers provided the system a damping increase of a factor of four for the first damper and three for the second damper. Both dampers were found to work well at low levels of vibration, suggesting that they can be used effectively to prevent resonant vibrations in flexible structure from initiating and building up.