• 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.

• Smart Structures and Systems
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• v.17 no.5
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• pp.837-857
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• 2016

In the present study, for first time the size dependent vibration behavior of a rotating functionally graded (FG) Timoshenko nanobeam based on Eringen's nonlocal theory is investigated. It is assumed that the physical and mechanical properties of the FG nanobeam are varying along the thickness based on a power law equation. The governing equations are determined using Hamilton's principle and the generalized differential quadrature method (GDQM) is used to obtain the results for cantilever boundary conditions. The accuracy and validity of the results are shown through several numerical examples. In order to display the influence of size effect on first three natural frequencies due to change of some important nanobeam parameters such as material length scale, angular velocity and gradient index of FG material, several diagrams and tables are presented. The results of this article can be used in designing and optimizing elastic and rotary type nano-electro-mechanical systems (NEMS) like nano-motors and nano-robots including rotating parts.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1435-1440
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• 2003

Although Dielectric Barrier Discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs(Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by electrostatic precipitator(ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl($20{\sim}100$ nm) and DOS($50{\sim}800$ nm) were generated by tube furnace and atomizer, respectively. For experimental conditions of 60 Hz, 11 kV, and 60 lpm, the particle collection efficiency for the hybrid system comprising DBD charger and ESP was over 85 %, based on the number of particles captured.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.338-342
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• 2010

Co, $Fe_3O_4$ and Co/$Fe_3O_4$ nanoparticles were synthesized by a polyol process in order to develop their new applications and improve chemical, magnetic properties. The synthesis involved a polyol process using Fe, Co acetylacetonate as precursors and 1-2 hexadecanediol as the polyol. The synthesized $Fe_3O_4$ and Co/$Fe_3O_4$ nanocomposite particles were monodispersed and self arrayed ranging in size of 8~10 and 10~25 nm, respectively. The Co nanoparticle has a crystallite size of 10~40 nm. The synthesized nanoparticles were characterized by their structural, morphological, compositional and magnetic properties using TEM-EDS, XRD, and PPMS techniques.

• Journal of Dairy Science and Biotechnology
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• v.23 no.1
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• pp.27-37
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• 2005

The development of functional foods started booming from several years ago in the world. The size of functional materials are in the range of micrometer level. This size can be much smaller into nanometer level to be more effective. We face some problems from the materials, such as flavor, taste, color, viscosity, etc. in functional materials. The problems can be solved by micro / nanoencapsulation technique. This paper showed some results of the research related on the technique for functional milks and dairy products. The nono / microcapsules are the form of liquid instead of solid. Coating materials used were fatty acid esters, and core materials were lactase, iron, ascorbic acid. isoflavone, and chitooligosaccharide. The ranges of capsules are from 100 nm to 200 ${\mu}$m. The sample milks added nano/microcapsules were homogeneous and prevented the defects of core materials. It was observed that nano / microcapsules in milk and dairy products were effective as functional material without defaults. It was indicated that targeted functional foods can be developed further in various foods by nanotechnology.

• Carbon letters
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• v.7 no.4
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• pp.271-276
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• 2006

Porous carbon materials were prepared with a thermal treatment of coal tar pitch at 550 in the Ar gas. Growth, merger, and distribution of pore were characterized with scanning electron microscopy as variation ascending temperature gradient and chamber pressure. After graphitizing at the 2600 (1 hr.), walls and connecting parts between pores were investigated with X-ray diffraction patterns. Wall thickness and pore size decreases as increasing ascending temperature gradient, and pore size becomes homogeneous. Graphite quality and thermal conductivity become higher due to the enhanced orientation of walls and connecting parts between pores.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1573-1574
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• 2009

Fullerene/polystyrene nanoparticles having the average size of 300 nm ~ 1 ${\mu}m$ were prepared by emulsion polymerization in aqueous medium. Poly(vinyl pyrrolidone) and potassium persulfate were used as a dispersant and an initiator, respectively. The contents of fullerene in the nanoparticle were controlled to be from 10 to 57 wt% by varying the feed ratio, which was confirmed by IR-spectroscopy, thermogravimetric analyses, and elemental analyses. Dynamic light scattering experiments revealed the particles have a broad size distribution. Further characterizations of the nanoparticles were performed by using SEM and TEM observation. The high content of fullerene in the particles will find applications in photovoltaic and organic semiconducting area.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.937-939
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• 2007

Carbon nanotubes (CNTs) have used as an electron field emitter of the field emission display (FED) due to their characteristics of high-electron emission, rapid response and low power consumption. However, to commercialize the FED with CNT emitter, some fundamental problems regarding life time and emission efficiency have to be solved. In this study, we investigated the $TiO_2$ coated CNT as a field emitter. $TiO_2$ nanoparticles can coated on CNT surface by chemical solution method. $TiO_2$ nanoparticles had uniform size with the average size of about 2.4 nm to 3.1 nm. Field emission performance of CNT coated with $TiO_2$ nanoparticles was evaluated and discussed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.152-153
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• 2006

We demonstrate the methodology of engineering the multi-component ceramic nanopowder with precise morphology by nanoblast calcinations decomposition of preliminary engineered nanoreactors. Multiple explosions of just melted $C_3H_6N_6O_6$ embedded into preliminary engineered nanoreactors break apart the agglomerates due to the highly energetic impacts of the blast waves. Also, the solid-solubility of one component into the other is enhanced by the extremely high local temperature generated during each nano-explosion in surrounding area. This methodology was applied for production of agglomeratefree nano-aggregates of $Gd_{20}Ce_{80}O_{1.95}$ with an average size of 42 nm and $LaSrGaMgO_{3-x}$ nanopowder with an average aggregate size of 83 nm.

• 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.