• Journal of Powder Materials
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• v.10 no.1
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• pp.51-56
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• 2003

To investigate the effect of the parameters of the plasma arc discharge process on the particle formation and particle characteristics of the iron nano powder, the chamber pressure, input current and the hydrogen volume fraction in the powder synthesis atmosphere were changed. The particle size and phase structure of the synthesized iron powder were studied using the FE-SEM, FE-TEM and XRD. The synthesized iron powder particle had a core-shell structure composed of the crystalline $\alpha$-Fe in the core and the crystalline $Fe_3O_4$ in the shell. The powder generation rate and particle size mainly depended on the hydrogen volume fraction in the powder synthesis atmosphere. The particle size increased simultaneously with increasing the hydrogen volume fraction from 10% to 50%, and it ranged from about 45nm to 130 nm.

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.21-26
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• 2006

A optical head unit for nano optical probe array was developed. The optical probe array is generated by Talbot effect. The shape and thickness of microlens array(MLA) were designed to minimize the spot size at the foci of MLA. To increase the optical efficiency of the system and obtain the large tolerance for fabrication, aperture size was theoretically optimized. Then microlens illuminated aperture array(MLIAA) as an optical head unit was fabricated using a ultra violet(UV) molding process on aluminum aperture array. In this process, Al aperture array was fabricated separately using the photolithography and reactive ion etching(RIE) process. Optical properties of the generated optical probes were measured and compared at Talbot distance from the aperture array having a diameter of $1{\mu}m$ and MLIAA.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1043-1047
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• 2003

With the advancement of micro-systems and nanotechnology, the need for ultra-precision fabrication techniques has been steadily increasing. In this paper, a novel nano-structure fabrication process that is based on the fundamental understanding of nano-scale tribological interaction is introduced. The process, which is called Mechano-Chemical Scanning Probe Lithography (MC-SPL), has two steps, namely, mechanical scribing for the removal of a resist layer and selective chemical etching on the scribed regions. Organic monolayers are used as a resist material, since it is essential for the resist to be as thin as possible in order to fabricate more precise patterns and surface structures. The results show that high resolution patterns with sub-micrometer scale width can be fabricated on both silicon and various metal surfaces by using this technique.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.71-75
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• 2006

The application of focused ion beam (FIB) technology in micro/nano machining has become increasingly popular. Its usage in micro/nano machining has advantages over contemporary photolithography or other micro/nano machining technologies such as small feature resolution, the ability to process without masks and being accommodating for a variety of materials and geometries. The target of this paper is the analysis of FIB sputtering process according to tilt angle, dwell time and overlap for application of 3D micro and pattern fabrication and to find the effective beam scanning conditions using Taguchi method. Therefore we make the conclusions that tilt angle is dominant parameter for sputtering yield. Burr size is reduced as tilt angle is higher.

• Journal of the Korean Ceramic Society
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• v.39 no.4
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• pp.336-340
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• 2002

Pure and nano-sized $TiO_2$ and $CaTiO_3$ powders were fabricated by a polymeric steric entrapment route and planetary milling process. An ethylene glycol was used as a polymeric carrier for the preparation of organic-inorganic precursors. Titanium isopropoxide and calcium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. At the optimum amount of the polymer, the metal cations were dispersed in solution and a homogeneous polymeric network was formed. The dried precursor ceramic gels were turned to porous powders through calcination process. The porous powders were crystallized at low temperatures and the crystalline powders were planetary milled to nano size.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.321-322
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• 2006

Nano-structured ceramics, which consist of structural elements with nanometer-size crystallites, are expected to show various unusual properties. We developed the novel nano-structured ceramics which consists of $Si_3N_4$ and TiN and a self-lubricant material. The ceramics was fabricated by powder metallurgy process using mechano-chemical grinding process and short-time sintering process. Each grain size of matrix and the self-lubricant particle was under about 50 nm and a few namometer. It showed high wear resistance and low friction coefficient by controlling of microstructure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.29-34
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• 2005

A optical head unit for nano optical probe away was developed. The optical probe array is generated by Talbot effect. The shape and thickness of microlens array(MLA) were designed to minimize the spot size at the foci of MLA. To increase the optical efficiency of the system and obtain the large tolerance for fabrication, aperture size was theoretically optimized. Then microlens illuminated aperture array(MLIAA) as an optical head unit was fabricated using a ultra violet(UV) molding process on aluminum aperture array. In this process, Al aperture array was fabricated separately using the photolithography and reactive ion etching(RIE) process. Optical properties of the generated optical probes were measured and compared at Talbot distance from the aperture array having a diameter of $1{\mu}m$ and MLIAA.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.628-631
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• 2003

This study describes a new mastless nano-fabrication technique of Pyrex 7740 glass using the combination of nanomachining by nano-indenter XP and HF wet etching. First, the surface of a Pyrex 7740 glass specimen was machined by using the nano-machining system, which utilizes the mechanism of the nano-indenter XP. Next, the specimen was etched by HF solution. After the etching process, the convex structure or deeper hole is made because of masking or promotion effect of the affected layer generated by nano-machining. On the basis of this interesting fact. some sample structures were fabricated.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.30-35
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• 2009

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1921-1926
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• 2003

Nano-imprint technology has been vigorously studied by many researchers for it is one of the most promising technologies for manufacturing the pattern with its critical dimension below 100nm. In the nano-imprint technology, nano patterns are transferred on a polymer film and the transferred patterns are used as an etch mask to define the designed patterns on a substrate or a metal layer. To this end, it is important to keep the residual thickness of the imprinted polymer film uniform. In this study, a novel measurement technique to measure the residual thickness of films is proposed based on nanoindentation theory. This technique has advantages of saving time and measuring the residual thickness of highly-localized portions in comparison with other techniques, but has limitation of requiring calibration process.