• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.71-79
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• 2008

In the manufacture of flat panel display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic suspension device far glass panels where the glass panel is supported by electrostatic forces without any mechanical contact is proposed. 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. Using this scheme, a $100{\times}100mm^2$ glass panel was levitated stably with airgap variation decreasing down to $1\;{\mu}m$ at an airgap of $100\;{\mu}m$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.125-126
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.34-41
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• 2005

There is a strong demand fur the contactless transportation device fur a hard disk and silicon wafer without contaminating and damaging them. To fulfill this requirements, A transportation device fur them has been proposed. But the device needs many of costly displacement sensors positioned along the transportation interval and possesses a very complicated controller and driving scheme. To overcome those kinds of drawback, in this paper, we present a very simple and cost-effective transportation device which only consists of a linear guide, very simple electrostatic suspension system and driving circuit of stepping motor. The principle of stable suspension by relay feedback control, derivation of lateral restoring force, the design of transportation system are described, fellowed by the experimental system. Experimental results show that a 3.5-inch hard disk has been transported with a speed of approximately 20mm/s while being suspended stably at a gap of 0.25mm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.287-288
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.76-85
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• 2006

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass panels is proposed. This device can directly drive a glass panel and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic farces on the glass panel and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass panels is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass panel has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• Electronics and Telecommunications Trends
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• v.27 no.5
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• pp.134-149
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• 2012

본고에서는 차세대 스마트 인프라 준거틀로서 '만물지능통신 기반 초연결 인프라' 개념을 제시한다. 동 개념이 대두하게 된 근거 기반으로 기술적 관점에서 스마트 기술혁신과 인프라 혁신 간의 상호관계성, 문명사적 관점에서 정보 교통 에너지 인프라 간의 공진화 과정을 거시적으로 개관한다. 그리고 초연결 클라우드 컴퓨팅, 만물지능통신망과의 선순환 관계에서 기존 인프라의 고도화와 동시에 정전교(情電交) 초연결 인프라의 탄생과 발전 방향을 모색한다. 또한 EU의 중장기 R&D 전략의 공통성과 도출을 위한 분산화된 협업시스템으로 부상하고 있는 SoS(System of Systems) 모델을 초연결 인프라의 프로토타입으로 검토한다. 이러한 작업을 기반으로 '물리적 인프라의 추상화' 그리고 '추상화한 인프라의 현실 세계로의 실체화'라는 관점에서 초연결 인프라로의 재편 메커니즘을 분석하고, 초연결 인프라를 지향한 공통 플랫폼과 그 실현을 위한 기술적 정책적 함의를 도출한다.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.6
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• pp.454-461
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• 2000

Electrostatic suspension offers an advantage of directly suspending various materials such as conductive materials, semiconductors and dielectric materials without any mechanical contacts. This is a specific feature compared with electromagnetic suspension which can suspend only ferro-magnetic material. In general, the electrostatic suspension systems require position sensors for stabilizing the suspended object. Therefore, a lot of displacement sensors and a switching circuit are required for moving the object through a long distance. In order to circumvent this problem, this paper proposes a self-sensing method which can provide the gap displacement between electrodes and suspended object without external sensors. Moreover a simple on-off controller is presented for stabilization. Experimental validation of the proposed scheme has been performed through the successful levitation of a 4-inch silicon wafer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.3
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• pp.477-484
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• 2000

Microcontamination caused by particle deposition on the head disk interface threatens the reliability of hard disk drive. Design of slider rail to control contamination becomes an important issue in magnetic recording. In this paper, how particles adhere to the slider and the disk is examined. To investigate accumulation mechanism of the particles, trajectory of the particles in a slider/disk interface is simulated with considering various forces including drag force, gravitational force, Saffman lift force, and electrostatic force. It is found that the charged particles can easily adhere to the slider or disk surface, if an electric field exists between the slider and the disk. It is supposed that the vertical motion of the particles should be related with not only Saffman force but also electrostatic force.

• Fire Science and Engineering
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• v.33 no.4
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• pp.130-139
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• 2019

The electronics factory fire, that occurred at 15:40 on August 21, 2018, killed nine people and injured six. This study analyzes the causes of many of the casualties from the fire, and is based on fire investigation results and so on. The findings suggest that major causes included failure of the automatic alarm system to function, failure of the emergency broadcasting system to function, the fire suddenly spreading due to polyurethane foam in a ceiling on the 4thfloor, a power outage immediately after the fire started, a sprinkler system that was not working, a delay in reporting the fire, and improper management of fire facilities by a fire safety management company.

• Composites Research
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• v.35 no.6
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• pp.378-393
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• 2022

As an emerging power generation technology, triboelectric nanogenerators (TENGs) have received increasing attention due to their boundless promise in energy harvesting and self-powered sensing applications. The recent rise of soft robotics has sparked widespread enthusiasm for developing flexible and soft sensors and actuators. TENGs have been regarded as promising power sources for driving actuators and self-powered sensors, providing a unique approach for the development of soft robots with soft sensors and actuators. In this review, TENG-based soft robots with different morphologies and different functions are introduced. Among them, the design of biomimetic soft robots that imitate the structure, surface morphology, material properties, and sensing/generating mechanisms of nature has greatly benefited in improving the performance of TENGs. In addition, various bionic soft robots have been well improved compared to previous driving methods due to the simple structure, self-powering characteristics, and tunable output of TENGs. Furthermore, we provide a comprehensive review of various studies within specific areas of TENG-enabled soft robotics applications. We first explore various recently developed TENG-based soft robots and a comparative analysis of various device structures, surface morphologies, and nature-inspired materials, and the resulting improvements in TENG performance. Various ubiquitous sensing principles and generation mechanisms used in nature and their analogous artificial TENG designs are demonstrated. Finally, biomimetic applications of TENG enabled in tactile displays as well as in wearable devices, artificial electronic skin and other devices are discussed. System designs, challenges and prospects of TENGs-based sensing and actuation devices in the practical application of soft robotics are analyzed.