• 한국정밀공학회지
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• 제19권9호
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• pp.179-185
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• 2002

Solid state deformation of PZT is effective for the micron scale displacement. Inch-worm gets large linear displacement by incrementally summing displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the small size and light weight of inch-worm. Mechanical vibration induced by low stiffness may degenerate the motion accuracy of the inch-worm. In this paper, dynamic characteristics of the inch-worm are modeled by using the frequency domain curve fitting based on the experimental frequency response function. SMC (sliding mode control) is examined for motion control of the inch-worm. Simulation and experimental results show that the inch-worm with SMC scheme is feasible for the precise displacement device.

• 한국공작기계학회논문집
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• 제14권5호
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• pp.1-6
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• 2005

Machining is a one of the broadly used manufacturing process to produce the parts, products and various molds and dies. The environmental impact due to aerosol generation via atomization process is a major concern associated with environmental consciousness. This paper presents the experimental results to analyze the characteristics of cutting fluid aerosol generation in grinding process. Experimental results show that the generated fine aerosol which particle size less than 10micron appears near worker's breath zone under given operational conditions. The aerosol concentration is much higher enough to affect human health risk with its generated aerosol quantities. This quantitative analysis can be provided the basic knowledge f3r further research for environmentally conscious machining technology developments.

• 한국표면공학회지
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• 제25권1호
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• pp.1-7
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• 1992

The formation of manganese ferrite has been performed to investigate some properties according to the variation of compositions, pH, current density by electrolysis. It has been found that the amount of oxidized weight of anode were increased with increasing current density. The amount of oxidized weight of anode were most in pH 10. As the result of X-ray diffraction Mn Fe₂O₄ crystal composition in pH13. When the particles of Mn/sub x/ Fe/sub 3-x/O₄ were heated at 300℃, it has been shown typical Mn Fe₂O₄(JCPDS Card No. 10-319) in X=1 composition. As the result of SEM observation, the size of MnFe₂O₄ particles were about 0.1㎛, the shape of particles were spherical type. According to the above mentioned experimental condition, 0.1-0.5㎛ sub-micron particles of manganese ferrite were formed from the wasted manganese dry cell, through washing → reduction → electrloysis.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.808-810
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• 2005

Inexpensive large area arrays of thin film transistors (TFTs) on flexible substrates will enable many new display products that cannot be cost effectively manufactured by conventional means. This paper presents a new approach for low cost manufacturing of electronic devices using roll-to-roll (R2R) processes exclusively. It was developed in partnership by Hewlett Packard Laboratories and Iowa Thin Film Technologies (ITFT), a solar cell manufacturer. The approach combines ITFT's unique processes for vacuum deposition and etching of semiconductors, dielectrics and metals on continuous plastic webs with a method HP has invented for the patterning and aligning the multiple layers of a TFT with sub-micron accuracy and feature size.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.722-723
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• 2006

A new method has been developed to fabricate microcomponents by a combination of photolithography and sintering of metallic powder mixtures, without the need for compression and the addition of Mg. This involves (1) the fabrication of a micromould, (2) mould filling of the powder/binder mixture, (3) debinding and (3) sintering. The starting powdered materials consisted of a mixture of aluminium powder(average size of 2.5 um) and alloying elemental powder of Cu and Sn(less than 70nm), at appropriate proportions to achieve nominal compositions of Al-6wt%Cu, Al-6wt%Cu-3wt%Sn. This paper presents detailed investigation of debinding behaviour and microstructural development.

• Carbon letters
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• 제7권1호
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• pp.27-33
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• 2006

Carbon-ceramic composites were fabricated by using fly ash and PANOX fibers as reinforcement. Fly ash, because of its small size particles e.g. submicron to micron level can be effectively dispersed along with fibrous reinforcements. Phenolic resin was used as carbon precursor. Both dry as well as wet methods were used for forming composites. The resulting composites were characterized for their microstructure, thermal and mechanical properties. The microstructure and mechanical properties of composites are found to be dependent on type of the fly ash, fibrous reinforcements as well as processing parameters. The addition of fly ash improves hardness and the fibers, which get co-carbonized on heat treatment, increase the flexural strength of the carbon-ceramic composites. Composites with dual reinforcement exhibit about 30-40% higher strength as compared to the composites made with single reinforcement, either with fly ash as filler or with chopped fibers.

• 한국세라믹학회지
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• 제26권2호
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• pp.221-227
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• 1989

To investigate the development and densification YBa2Cu3O7-x(1-2-3) superconducting phase, the 1-2-3 phase powders have been prepared by citrate and nitrate processes with changing calcination temperature. Nearly pure 1-2-3 phase peaks have been obtained by calcining the precursor in air at 90$0^{\circ}C$ for 2.5h in citrate process but at 95$0^{\circ}C$ for 2.5h in nitrate process. The sintering density of citrate derived sample calcined at 80$0^{\circ}C$ has been about 4% higher than that calcined at 90$0^{\circ}C$, although the compacting density has been lower at 80$0^{\circ}C$ calcination. This can be explained that the 1-2-3 phase particles formed at 80$0^{\circ}C$ have reactive sub-micron size which has good sinterbililty.

• 전기학회논문지
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• 제57권12호
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• pp.2249-2254
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• 2008

A non-thermal micron size plasma needle is applicable for medical treatment because it includes radicals, charged particles, ultraviolet emission, and strong electric fields. The electric fields around the plasma needle device driven by a radio frequency wave are investigated in order to calculate the power delivered to the cell. A commercial multi-physics code, CFD-ACE, was utilized for the calculation of electric fields for the optimization of the needle structure. The electric field and energy absorption profiles are presented with the variation of the device structure and the distance between the needle and tissues. The living tissues effectively absorb the radio frequency power from the plasma needle device with the covered pyrex structure.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.282-287
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• 2005

This paper presents the experimental results to analyze the characteristics of cutting fluid aerosol generation in grinding process. Machining is a one of the broad manufacturing process to produce the parts, products and various molds and dies. The environmental impact due to aerosol generation via atomization process is a major concern associated with environmental consciousness. Experimental results show that the generated fine aerosol which particle size less than 10 micron appears near worker's breath zone under given operational conditions. The aerosol concentration is much higher enough to affect human health risk with its generated aerosol quantities. This qualitative analysis can be provided the basic knowledge for further research for environmentally conscious machining technology developments.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.129-132
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• 2003

Silica/SUS composite membranes were prepared for CO removal from products of methanol steam reforming. A support was prepared by coating Ni powder of sub-micron and SiO$_2$ sols of particle size of 500nm and 150nm in turns on a porous stainless steel (SUS) substrate. Silica top layer was coated on the modified support using colloidal sol with nanoparticle. As a result of mixture gas permeation test of silica composite membrane using H$_2$(99%)/CO(1%), CO concentration of 10000 ppm was reduced to under 81 ppm, which is acceptable in PEMFC anode gas specification. Permeation mechanism through the membrane was mainly molecular sieving.