• 한국생산제조학회지
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• 제21권3호
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• pp.401-407
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• 2012

The recent manufacturing process in the thin wafers and flat panel necessitate new approaches to reduce handling fragile and surface-sensitive damage of components. This paper presents a new pneumatic levitation for non-contact handling of parts and substrates. This levitation can achieve non-contact handling by blowing air into an air pressure pick-up head with radial passages to generate a negative pressure region. Negative pressure is caused by the radial air flow by nozzle throat and through holes connecting to the bottom region. The numerical analysis deals with the levitational motion with different design factors. The dynamic motion is examined in terms of force balance(dynamic equilibrium) occurring to the flow field between two objects. The stable equilibrium position and the safe separation distance are determined by analyzing the local pressure distribution in the fluid motion. They make considerable design factors consisting the air pressure pick-up head. As a result, in case that the safe separation distance is beyond 0.7mm, the proposed pick-up head can levitate stably at the equilibrium position. Furthermore, it can provide little effect of torque, and obtain more wide picking region according to the head size.

• 한국생산제조학회지
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• 제21권4호
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• pp.563-569
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• 2012

In the semiconductor and display device production processes, the handling of sensitive objects needs new carrying technology. Floating carrying motion is a practical alternative solution for non-contact handling of parts and substrates. This paper presents a study of through paths inside the air pressure pick-up head to generate the floating motion. The air motion by conceptual designed paths inside the head gradually develops positive pressure and vacuum between narrow objects. Positive pressure occurs through the head tip before discharging outside of the head. Negative pressure is developed by evacuating the inside head bottom as result of the radial flow connecting the vertical through-holes. The numerical analysis was done to figure out the stable levitation caused by the two acting forces between surfaces. In comparing with the standard case that the levitation gap gets 0.7-0.9 mm, it confirms the suggested head characteristics to show floating capacity in accordance with the head size, number of through-hole, and locations of through-hole in succession of conceptual design for a prototype.

• 한국생산제조학회지
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• 제22권6호
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• pp.937-944
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• 2013

This paper describes an improved model that can be used for configuring a non-contact pneumatic head to handle a large sheet of glass. The cylindrical head model is of a large size (70 mm). It operates on vortex flow, which can simultaneously generate suction and repulsion over the flat object's surface. The head allows for the minimal non-contact lifting of objects weighing over 3N by using reference conditions (working pressure and head dimensions). Additionally, a functional flow-guide is applied for inducing a developing tangential vortex flow to increase suction and repulsion to the reference head. The cylindrical flow-guide is associated with relatively low tangential velocity. The improved model generates greater lifting force than the reference model, as verified experimentally.

• 한국생산제조학회지
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• 제23권5호
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• pp.435-442
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• 2014

This paper describes an improved design model that can be used to configure a non-contact pneumatic device to turn a large sheet at the in-line system. For rotational moving in the conveyor system, the conventional method is to turn the system itself. The improved non-contact pick-up system mainly uses 8 pairs of L-shaped latches and 12 swirl type heads. It is positioned above the upward air flow table. This system performs the non-contact gripping and side-edge contact support in the vertical and rotational directions to hold the self-weight of a large flat sheet. A non-contact air head can exert a sufficient gripping ability at 4N lower than the standard working pressure. The side latches support 60% of the lifting force required. Through structural and flow analysis, the working conditions were simultaneously considered in accordance with the deflection and flatness of the glass.

• 한국지구과학회지
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• 제30권2호
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• pp.196-209
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• 2009

2005년 1월부터 12월까지 지속적으로 몽골과 중국 북부의 사막과 건조지대에서 모래폭풍의 발생, 이동 그리고 한국에서 먼지침전(황사)을 모니터링하였다. NOAA 위성의 AVHRR(Advanced Very High Resolution Radiometer) 관측 자료를 직접 수신하여 false colour 합성영상을 만들어 모래폭풍의 발생과 이동 사례를 중점 분석하였다. 또한 모래폭풍 발원지의 풍하측에 위치한 한국 중부의 청원에서 PM10 농도가 $190{\mu}g\;m^{-3}$ 이상인 황사 사례에 대한 PM10, PM2.5농도와 시정 그리고 $O_3,\;NO_2,\;CO,\;SO_2$ 농도의 변동을 분석하였다. 2005년에는 발원지에 적설과 강력한 고기압, 저기압의 이동이 미흡하여 강한 모래폭풍의 발생이 적었고 한국에서도 황사의 발생 빈도가 1997-2005년의 평균과 비교하여 적었다. 한국에는 2005년 총 7회, 11일간의 황사 사례가 발생하였다. 여름에는 발원지가 습하고 바람이 약해 모래폭풍의 발생이 적었으며, 한국에서도 황사의 발생이 없었다. 발원지에서 발생한 모래폭풍이 중국의 대도시와 산업지대를 거치지 않고 한국으로 직접 이동할 경우, 먼지침전에 따른 PM2.5 농도는 PM10 농도의 20% 이하였다. 그러나 모래폭풍이 중국 동부의 산업지역을 거쳐 한국으로 이동할 경우 인위적 대기오염 물질이 함께 유입되어 PM2.5 농도가 증가하여 PM10농도의 25%이상을 나타내었다. 또한 2005년에는 사막에서 날아온 모래 먼지의 PM10농도가 $190{\mu}g\;m^{-3}$ 이하여서 황사로는 미흡한 5개 이상 사례를 관측 및 분석하였다.