• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.125-125
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• 2003

• 전기의세계
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• v.37 no.4
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• pp.58-70
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• 1988

이하에서는 자기부상철도의 기본적인 동작원리와 특징, 개발 및 실용의 현상, 고속 시스템의 실용화의 전망, 종래의 철차륜, 철레일 방식의 철도와 비교했을 경우의 특징등에 대해서 설명한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.969-974
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• 2003

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a dc voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to 1 $\mu\textrm{m}$ at an airgap of 100 $\mu\textrm{m}$

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.63-72
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• 2008

A new method for the electrostatic suspension of disk-shaped objects is proposed which is based on a time-optimal control scheme and deploys only high-voltage power supplies that can deliver dc voltages of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification and objects can be suspended stably even in vacuum environment. Using this scheme, an aluminium disk used in a 3.5-inch HDD was suspended stably at an airgap of 0.3mm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.263-264
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• 2006

A new method for the electrostatic suspension of disk-shaped objects is proposed which is based on a time-optimal control scheme and deploys only high-voltage power supplies that can deliver do voltages of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification and objects can be suspended stably even in vacuum environment. Using this scheme, an Aluminium disk employed in a 3.5-inch HDD was suspended stably at an airgap of 0.3mm.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.60-69
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• 2005

In electrostatic suspension system of thin plates like a silicon wafer or an aluminum disk for hard disk applications, the lateral restoring force exerted on a suspended object plays an important role since the lateral motion of the suspended object, owing to the inherently stable restoring forces, can be passively stabilized without any active control of it. This paper reports about the measurement apparatus of the lateral restoring force originating from a relative translation of the suspended object with respect to the electrodes-for-suspension. An approximate calculation of the lateral force in disk-shaped objects, the structure of the measurement apparatus, a measurement method, stabilization condition and the guideline in designing the measurement apparatus are described. Experimental results obtained by using a 3.5-inch aluminum disk as a suspended object are presented as well in order to assess the magnitude of lateral force and stiffness, and also verify the usefulness of the measurement apparatus.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.56-64
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• 2005

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to $1 {\mu}m$ at an airgap of $100{\mu}m$.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.80-91
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• 2008

Electrostatic forces have an advantage of directly levitating not only non-ferromagnetic metals but also semiconductors, such as silicon wafers, and dielectric materials like glass. This paper describes the characteristics of electrostatic forces and electrostatic suspension system, followed by the basic principle of 1-DOF(degree of freedom) electrostatic suspension system, and the structures of electrodes-for-suspension and voltage supplying methods to the electrodes in 1-DOF model. This paper also discuss about the minimum number of electrodes needed to control n-DOF motion of the suspended object and represents some desirable electrode patterns to stabilize the 6-DOF motion of the object. In the near future, electrostatic suspension system is expected to be applied to industrial manufacturing processes, for example, to the manufacture of semiconductor devices and/or flat panel display devices.

• Electric Engineers Magazine
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• v.221 no.1
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• pp.30-40
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• 2001

규제완화가 진행되고 있는 미국에서는 거대화 복잡화하는 전력거래에 대한 전력계통에 신뢰도를 유지하는 것이 중요한 과제로 되어있다. 그 중에서 1996년도 여름철에 연달아서 발생한 수백만호 규모로 영향이 미친 광역 정전사고를 계기로 공급신뢰도의 문제가 크게 부상되고 있다.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.104-110
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• 2006

A design and control of electrostatic suspension system for flexible objects is presented. A number of electrode pairs of which the number depends on the object flexibility are positioned above the object and the voltages applied to each electrode pair are controlled, independently on the others, on the basis of the gap length. To implement the system with low cost and compactness, switched-voltage control scheme that is based on the relay feedback control is utilized. Relay feedback control method deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity and thus high voltage amplifiers that are costly and bulky are not needed any more. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping originating from the electrodes and levitated object. Employing fourteen electrode pairs, a thin aluminum plate with a thickness of 0.1 mm has been suspended at a gap length of 0.75mm.