• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.81-86
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• 2002

이전에 Magnetic Fluid를 이용하여 의료기기 등에 사용할 목적으로 Linear Actuator를 설계, 제작하였다. 그러나 이 모델은 공극의 높은 자기저항으로 인해 펌핑 압력이 낮고, 그 부피 또한 크다. 따라서 본 논문에서는 Yoke를 이용하여 Linear Actuator를 소형화하고 자기저항을 최소화함으로써 펌핑 압력을 향상시켰다. 또한 Linear Actuator의 3D해석을 통하여 Yoke의 폭, 두께, 간격에 대한 최적 크기를 계산하고 설계하였으며, 실제 제작 및 실험을 하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.93-94
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• 2010

• Journal of Sensor Science and Technology
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• v.27 no.2
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• pp.99-104
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• 2018

A micro electromagnetic actuator with high vibration efficiency is proposed for use in an implantable hearing device. The actuator, which can be implanted in the middle ear, consists of membranes based on the stainless steel 304 (SUS-304), and other components. In conventional actuators, in which a thick membrane and a silicone elastomer are used, the size reduction was difficult. In order to miniaturize the size of the actuator, it is necessary to reduce the size of the actuation potion that generates the driving force, resulting in reduction of the electromagnetic force. In this paper, the electromagnetic actuator is further miniaturized by the metal membrane and the vibration amplitude is also optimized. The actuator designed according to the simulation results was fabricated by using micro-electro-mechanical systems (MEMS) technology. In particular, a $20{\mu}m$ thick metal membrane was fabricated using the erosion process, which reduced the length of the actuator by more than $400{\mu}m$. In the experiments, the vibration displacement characteristics of the optimized actuator were above 400 nm within the range of 0.1 to 1 kHz when a current of $1mA_{rms}$ was applied to the coil.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.147-154
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• 2005

A precision hi-directional actuator for a high precision leveling system with $Z{\Theta}_x{\Theta}_y$ motions is proposed and designed in this paper. The actuator is composed of a force generation structure, a guide mechanism, and a symmetric structure. At first, its driving force is generated by a change of flux in air gaps by permanent and changeable flux. The permanent flux is generated by a permanent magnet. The changeable flux is created by variable current flowing through coil. The combination of permanent and changeable flux makes various flux densities in air gaps between moving part and fixed yokes. And then, the difference between flux densities in lower and upper gaps creates forces fur the $bi-direction({\pm}z)$ motion. The guide mechanism of this actuator is composed of two circular plates and one shaft. Reducing motions generated by forces except z-motion, these circular plates endow the actuator with high stiffness for fast settling time. And the function of the shaft is to transfer motion to an object. At last, total body has a symmetric structure to be stable on thermal error. The actuator is designed by MAXWELL 2D and ProMECHANICA. The designed actuator is evaluated by 8nm laser doppler vibrometer, dynamic signal analyzer, and simple PID controller.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.743-748
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• 2015

This paper reports the enhanced fabrication and characterization of a $3{\times}3$ array tactile actuator composed of cellulose acetate. The array tactile actuator, with dimensions of $15{\times}15{\times}1mm^3$, consists of 9 pillar-supported cells made from a cellulose-acetate molding. The fabrication process and performance test along with the results for the suggested actuator are explained. To improve the cell-array fabrication, a laser cut was adopted after the molding process. The displacement of the unit cell increased the input voltage and frequency. Various top masses are added onto the actuator to mimic the touch force, and the acceleration of the actuator is measured under actuation. When 2 kV is applied to the actuator, the maximum acceleration is 0.64 g, which is above the vibrotactile threshold. The actuation mechanism is associated with the electrostatic force between the top and bottom electrodes.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.979-984
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• 2007

This paper presents a new control mechanism for the proportional pressure control which is accomplished by electro-pneumatic regulator using two PZT actuators. The electro-pneumatic regulator of this study is 2-stage type and consists of two piezoelectric actuators, a controller and a main poppet valve. The piezoelectric actuators are multilayer bender type and are controlled by digital signal. Proportional pressure control technique is very important because that can derive improvement of product quality and driving ability in the pneumatic system. Solenoid actuator method for pressure control is widely used but this actuator has a high power consumption characteristics. So new actuator is required for the energy saving. In this study, PZT actuator for the pressure control was fabricated and experimented instead of the conventional type solenoid actuator. Experiments for the new control mechanism of the elector-pneumatic regulator were operated under the input condition of 0.4[MPa] and it was confirmed that this mechanism has a good control characteristics to the response sensitivity and hysteresis.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1234-1241
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• 2011

In this work the potential, and the perspectives of the dielectric elastomer actuator are overviewed briefly. As an exemplary work, we introduce a novel contractile artificial muscle actuator based on Synthetic Elastomer(SE). SE is the name of new dielectric elastomer material we have developed and its synthesis procedures and evaluations are described in the first. The contractile artificial muscle actuator is made by stacking the actuator unit one by one along the in thickness direction and finished up by bonding the multi-stacked actuator. Its possibility for the robotic actuator is discussed and demonstrated via experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.3
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• pp.253-263
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• 2004

The problem considered in this paper is about the collocation of sensor and actuator for the active control of sound and vibration. It is well-known that a point collocated sensor-actuator pair offers an unconditional stability with very high performance when it is used with a direct velocity feedback (DVFB) control, because the pair has strictly positive real (SPR) property. In order to utilize this SPR characteristics, a matched piezoelectric sensor and actuator pair is considered. but this pair suffers from the in-plane motion coupling problem with the out-of-plane motion due to the piezo sensor and actuator interaction. This coupling phnomenon limits the stability and performance of the matched pair with DVFBcontrol. As a new alternative, a point sensor and distributed piezoelectric actuator pair is also considered, which provides SPR property in all frequency range when the pair is implemented on a clamped-clapmed beam. The use of this sensor-actuator pair is highly expected for the applications to more practical active control of sound and vibration systems with the DVFB control strategy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.777-781
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• 2002

Recently, an optical disc system has been proposed using blue laser diode, high NA objective lens and groove only disc structure. A new method is needed to readout CD and DVD in this blue system. In order to readout CD and DVD in HD-DVD system, we adopted dual-lenses actuator in consideration of optical utilization efficiency, optical performance and insurance of sufficient W.D (working distance). This dual-lenses actuator has two objectives in radial direction, one is for CD/DVD and the other is for HD-DVD. We had to solve the induced problems of DC tilt increase, $2^{nd}$ resonance deterioration and AC sensitivity drop caused by disposing two lenses in an actuator. Especially, to solve AC sensitivity drop, we introduced two 2-pole magnets and separated focus and track magnetic circuits. Consequently we presented that dual-lenses actuator has been possessed good performance. And we measured eye patterns of CD, DVD and HD-DVD by using HD-DVD optical pick-up with dual-lenses actuator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.110-114
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• 2004

This paper deals with the dynamic characteristic analysis of linear actuator(LA) considered with coupling of mechanical spring system This application of linear actuator is increasing due to simple mechanical structure, a high efficiency, and a stable motional action. This paper proposed and analyzed the Serial Piston Actuator(SPA) by using mechanical spring system coupled with linear actuator through the simplified structure which was verified practical experiments.