• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.290-290
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• 2011

In this study Diamond-like carbon (DLC) films were deposited on p-type Si substrates using a Radio-Frequency magnetron Sputtering system. The DLC film was deposited by bombarding graphite target with a N2/Ar plasma mixture with various conditions: substrate, pressure, deposition time, temperature of substrate, power and ratio of gas mixture. The effect on the conduction and hardness of DLC thin films were investigated. The conduction of DLC films were measured by I-V measurement. In addition, Raman analysis was performed to study the chemical bonding structure. The hardness was measured by Nano indentation. Atomic Force Microscopy was used for determined surface morphology of DLC film.

• Macromolecular Research
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• v.13 no.5
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• pp.441-445
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• 2005

Thermoplastic polyurethane elastomer (TPUe) fiber mats were successfully fabricated by electrospinning method. The TPUe fiber mats were subjected to a series of cycling tensile tests to determine the mechanical behavior. The electrospun TPUe fiber mats showed non-linear elastic and inelastic characteristics which may be due to slippage of crossed fiber (non-bonded or physical bonded structure) and breakage of the electro spun fibers at junctions (point-bonded or chemical bonding structure). The scanning electron microscopy (SEM) images demonstrated that the point-bonded structures of fiber mats played an important role in the load-bearing component as determined in loading-unloading component tests, which can be considered to have a force of restitution.

• Journal of Powder Materials
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• v.10 no.3
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• pp.157-160
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• 2003

Phase contents and elemental composition of ultradispersed powders obtained by the electrical explosion of tin-leadalloy powders are investigated. It is demonstrated that during the explosion and subsequent cooling, surface layers of powder particles are enriched in lead compared to the initial alloy. The thermal stability of powders oxidizing in air is also investigated.

• Ceramist
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• v.9 no.6
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• pp.42-48
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• 2006

The structural ceramic, such as $A1_2O_3,\;ZrO_2\;and\;Si_3N_4$ have applied as several parts of precision machines, automotives and instruments for semiconductor. The mechanical properties depended on purity, morphology and microstructure of the ceramic and its fabrication process. High purity and fine starting powder for the structural ceramic was prepared mainly by wet process and powder processing such as milling, mixing, drying and granulating strongly influenced on the fabrication process. Powder processing included powder synthesis technology is essential for ceramic manufacture. Also, the advanced mechanical treat[neat in powder processing to create nano composite powder was developed to improve several properties of ceramic materials. Innovation of powder processing will lead to improve mechanical and functional properties of the ceramics.

• Transactions on Electrical and Electronic Materials
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• v.7 no.3
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• pp.118-122
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• 2006

Diamond-like carbon (DLC) films were prepared on silicon substrates by the RF PECVD (Plasma Enhanced Chemical Vapor Deposition) method using methane $(CH_4)$ and hydrogen $(H_2)$ gas. We examined the effects of the post annealing temperature on the tribological properties of the DLC films using friction force microscopy (FFM). The films were annealed at various temperatures ranging from 300 to $900^{\circ}C$ in steps of $200^{\circ}C$ using RTA equipment in nitrogen ambient. The thickness of the film was observed by scanning electron microscopy (SEM) and surface profile analysis. The surface morphology and surface energy of the films were examined using atomic force microscopy and contact angle measurement, respectively. The hardness of the DLC film was measured as a function of the post annealing temperature using a nano-indenter. The tribological characteristics were investigated by atomic force microscopy in FFM mode.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.469-477
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• 2016

The application of nanomaterials for electrodes of intermediate temperature solid oxide fuel cells (SOFC) is introduced. In conventional SOFCs, the operating temperature is higher than 1073 K, and so application of nanomaterials is not suitable because of the high degradation rate that results from sintering, aggregation, or reactions. However, by allowing a decrease of the operating temperature, nanomaterials are attracting much interest. In this review, nanocomposite films with columnar morphology, called double columnar or vertically aligned nanocomposites and prepared by pulsed laser ablation method, are introduced. For anodes, metal nano particles prepared by exsolution from perovskite lattice are also applied. By using dissolution and exsolution into and from the perovskite matrix, performed by changing $P_{O2}$ in the gas phase at each interval, recovery of the power density can be achieved by keeping the metal particle size small. Therefore, it is expected that the application of nanomaterials will become more popular in future SOFC development.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.676-677
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• 2006

Synthesis of zinc oxide nanorods, sheets and flower like structure were done by the sol-gel method using zinc acetate dihydrate and sodium hydroxide at $80^{\circ}C$ with 12 hours refluxing time nanorods, in case of as synthesized powder, with diameter of 20-60nm. Annealing at higher temperature (300 and $500^{\circ}C$,) in air ambient changes the morphology to sheet and flower like structure. The standard peak of zinc oxide was observed in IR at $523cm^{-1}$. The UV-VIS spectroscopy of zinc oxide shows a characteristic peak at 375nm.

• Macromolecular Research
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• v.16 no.2
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• pp.163-168
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• 2008

Polystyrene/gold nanoparticle (PS/AuNP) composite fibers were fabricated using an electrospinning technique. Transmission electron microscopy (TEM) showed that the diameters of the naphthalenethiol-capped gold nanoparticles (prior to incorporation into the PS fibers) ranged from 2 to 5 nm. UV-vis spectroscopy revealed the surface plasmon peaks of the gold nanoparticles centered at approximately 512 nm, indicating that nano-sized Au particles are well-dispersed in solution. This was consistent with the TEM observations. The electrospun nanofibers of PS/AuNP composites were approximately 60-3,000 nm in diameter. The surface morphology of the PS/AuNP composite and the dispersability of the Au nanoparticles inside of PS after electrospinning process were investigated by SEM and TEM. The thermal behavior of the pure PS and PS/AuNP nanocomposites and fibers were examined by DSC.

• Macromolecular Research
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• v.15 no.3
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• pp.211-215
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• 2007

Hybrid thin film nanostructures composed of metal nanoparticles (NPs) and self-assembled polymer films with different spatial distributions of NPs were analyzed by optical waveguide spectroscopy (OWS). Specifically, the dielectric constants were calculated using effective medium theory for the incorporation of 1 vol% Au NP into the block copolymer (BCP) films having a cylindrical nanodomain morphology. Three cases were considered: uniform distribution of NPs in the film; selective distribution of NPs only in the cylindrical domains; and segregation of NPs to the center of the cylindrical domains. The optical waveguide spectra derived from the calculated dielectric constants demonstrate the feasibility of experimentally distinguishing the composite nanostructures with different inner morphologies in the hybrid metal NP-BCP nanostructures, by the measurement of the dielectric constants using OWS.

• Bulletin of the Korean Chemical Society
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• v.21 no.6
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• pp.604-610
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• 2000

Drying-step in sol-gel processing was bypassed by exchanging alcoholic solvent in forsterite alcogel directly with MMA. By in-situ polymerization of the MMA, organic-inorganic nano-composite of PMMA-forsterite was prepared. As porous nature of inorganic networks in the gel was preserved and fixated in the composite, spherical morphology of PMMA was resulted. The PMMA-forsterite composite was optically transparent, machinable,mechanically sustainable, and thermally more stable than pristine PMMA. When doped with $Eu^{+3}$, inorganic moiety in the composite provided site environment that is very different from that in pristine PMMA. Prominent $^{5}D_0$ → $^{7}F_0$ transition at 578 nm, broken degeneracy in $^{5}D_0$ → $^{7}F_1$ and $^{5}D_0$ →$^{7}F_2$ transitions suggested that $Eu^{+3}$ was exclusively doped in the inorganic moiety of the composite, which had lower symmetry than the organic counterpart.