• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.241-241
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• 2007

• Journal of the Korean Magnetics Society
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• v.11 no.5
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• pp.184-188
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• 2001

Using a DC-sputter and changing the substrate temperature to room temperature and 200$\^{C}$, we manufactured each Co-22%Cr alloy thin-films, which has a uniform micro-structure at room temperature, and a fine self-organized nato structure (SONS) at the inside of the grain at the elevated temperature. We also investigated the microstructure and domain structure using a transmission electron microscope (TEM) and a magnetic force microscope (MFM). We managed to corrode selectively Co-enriched phase, then investigate the microstructure using a TEM. We found that it has a uniform composition when it is manufactured at room temperature, but, we found that it has a unique microstructure, which has a plate-like fine Co-enriched phase, with the formation of SONS at the inside of the grain at the elevated temperature. In MFM characterization, we found maze-type domains at the period of 5000 when the substrate temperature maintains at room temperature. We define that the maze-type domain has a disadvantage at the high density recording because it generates noises easily as the exchange coupling energy between the grains is big. On the other hand, there is only a fine domain structure at the period of 500 when the substrate temperature maintains at 200 $\^{C}$. We define that the fine domain structure has an advantage at the high density magnetic recording because it has thermal stability due to small exchange coupling energy.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.305-308
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• 2008

In this paper, the magnetic domain states and recordability of the molded magnetic nanopillars were examined and analyzed by magnetic force microscopy (MFM) measurement. We focused on the some of the technical issues for MFM measurement regarding the lift height and geometry of the MFM tip. The effects of MFM tip shape and lift height on the MFM resolution were analyzed. Finally, we showed that the magnetic film on each molded nanopillars has a single magnetic domain state.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.514-521
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• 2010

A new one-shot process was employed to fabricate proton exchange membranes (PEMs) over conventional solvent-casting process. Here, PEMs containing nano-dispersed silica nanoparticles were fabricated using one-shot process similar to the bulk-molding compounds (BMC). Different components such as reactive dispersant, urethane acrylate nonionmer (UAN), styrene, styrene sulfuric acid and silica nano particles were dissolved in a single solvent dimethyl sulfoxide (DMSO) followed by copolymerization within a mold in the presence of radical initiator. We have successfully studied the water-swelling and proton conductivity of obtained nanocomposite membranes which are strongly depended on the surface property of dispersed silica nano particles. In case of dispersion of hydrophilic silica nanoparticles, the nanocomposite membranes exhibited an increase in water-swelling and a decrease in methanol permeability with almost unchanged proton conductivity compared to neat polymeric membrane. The reverse observations were achieved for hydrophobic silica nanoparticles. Hence, hydrophilic and hydrophobic silica nanoparticles were effectively dispersed in hydrophilic and hydrophobic medium respectively. Hydrophobic silica nanoparticles dispersed in hydrophobic domains of PEMs largely suppressed swelling of hydrophilic domains by absorbing water without interrupting proton conduction occurred in hydrophilic membrane. Consequently, proton conductivity and water-swelling could be freely controlled by simply dispersing silica nanopartilces within the membrane.

• Polymer(Korea)
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• v.38 no.4
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• pp.544-549
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• 2014

Double layered film consisting of polyimide/polysiloxane and interface with nano domain structure was fabricated through stepwise layer formation and subsequent aging steps. During aging of film, nano phase separation occurred between the top layer polysiloxane and the upper layer of polyimide, which was observed by transmission electron microscope (TEM). A stable and uniform polysiloxane layer was obtained, showing the reproducible pressure-sensitive adhesion (PSA) property with the peel strength of 8-13 g/inch at even $300^{\circ}C$. In addition, the resulting polymide/polysiloxane film was thermo-stable up to $435^{\circ}C$, providing the promising properties suitable for application in microelectronics processing.

• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.144-148
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• 2007

In this paper, we analyzed the effect of the pattern height on the readback signal characteristics of the magnetic nanopillar tops and trench bottoms. In addition, we discuss the applicability of the present method to the production of patterned magnetic media, which can be obtained by depositing magnetic thin films on the molded nanopillars with passive heating. We found that the individual magnetic island deposited on each molded nanopillars with passive heating is a single magnetic domain and confirmed that its magnetization can be successfully reversed by applying an external magnetic field.

• Journal of Adhesion and Interface
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• v.18 no.1
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• pp.13-24
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• 2017

In this study, nanoparticles which encapsulated hydrophobic antimicrobial compounds with 50wt% of payload and 70%of solid content were prepared. These nanoparticles could be dispersed at water as well as various medium. Water dispersible organic-inorganic (O-I) hybrid nanoparticles were first prepared using alkoxysilane-functionalized amphiphilic polymer precursors through a conventional sol-gel process. Hydrophobic antimicrobial compound, Eugenol encapsulated nanoparticles were prepared using these O-I hybrid nanoparticles through a new nanoprecipitation process. The effect of various preparation on the size of nanoparticles, amount of payload, antimicrobial activity, and release rate of encapsulated compounds was investigated. All eugenol-encapsulated O-I nanoparticles regardless of preparation condition showed the same minimal inhibitory concentration (MIC) (50mg/ml) and 99% of antimicrobial activity for every strain. Their antimicrobial activity could maintain longer than two weeks. Especially, eugenol-encapsulated O-I nanoparticles prepared using tetraethoxysilane (TEOS) exhibited the highest payload (50wt%) and the lowest release rate which was owing to higher inorganic content in the O-I nanoparticles. And these O-I nanoparticles dispersed in hexanediol (HD) showed the highest antimicrobial activity and solid content (70wt%) because HD acted as a solvent as well as a antimicrobial agent.

• Polymer(Korea)
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• v.29 no.1
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• pp.1-7
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• 2005

Interpenetrating polymer network (PN) is a mixture of network polymers. The characteristics of IPN material is the control of morphology during the IPN synthesis. By controlling the relative kinetics of chemical reaction (as well as gellation) and phase separation, the morphology of IPN can be controlled to obtain materials with nano-scale domain and also the co-continuous phase. Other important advantage is the fact that the morphology is permanent due to the presence of the physical interlocking between the networks. The combination of hydrophilic polyurethane and hydrophobic polystyrene in IPN form provides enhanced blood compatibility due to the co-existence of the hydrophilic and hydrophobic domains in nano-scale on the surface. The reaction temperature, reaction pressure and the degree of crosslinking were varied during the IPN synthesis and the morphology and blood compatibility of the resulting IPN materials were studied.

• Polymer(Korea)
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• v.35 no.3
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• pp.238-243
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• 2011

Organic/inorganic hybrid materials have a lot of interest in various areas due to their fascinating properties. To control the location and dispersion of inorganic nanoparticles within polymer matrix. thiol-terminated polymeric ligands have been widely used to tune the surface property of nanoparticles. However, the specific binding between the thiol functional group and metal is unstable with increasing temperature. To archive the thermally-stable Au nanoparticles, we previously synthesized various UV-crosslinkable polymeric ligands, which have different compositions of polar, UV-crosslinkable azide unit comparing to non-polar 스티렌 units. After crosslinking the Au nanoparticles, it was found that the nanoparticles had superb stability at high temperature (above $180^{\circ}C$). In this work, we used thermally-stable Au nanoparticles to control the location within the polymer matrix. By changing the amount of polar azide units in the polymeric ligands, we could precisely control the location of nanoparticles from one domain to the interface of block copolymer templates.

• Journal of the Korean Applied Science and Technology
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• v.24 no.2
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• pp.174-181
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• 2007

In this study, $SiO_2/poly(ethylene-co-vinyl$ alcohol)(EVOH) hybrid coating materials with gas barrier property could be produced using sol-gel method. The biaxially oriented polypropylene (BOPP) substrate with surface pretreatment was coated with the prepared hybrid sols containing various inorganic silicate component by a spin coating method. Crystallization behavior of the hybrids was investigated in terms of analysis of X-ray diffraction and cooling thermogram from DSC experiment. From the morphological observation of the $SiO_2/EVOH$ hybrid gel, it was confirmed that there existed an optimum content of inorganic silicate precursor, Tetraethylorthosilicate (TEOS), to produce hybrid materials with dense microstructure, exhibiting uniformly dispersed silica particles with average size below 100 nm. When TEOS was added at below or above the optimum content, particle clusters with large domain were observed, resulting in phase separation. This morphological result was found to be in good agreement with that of oxygen permeability of the hybrid coated films. In the case of film coated with hybrid prepared from addition of 0.01 - 0.02mol of TEOS, a remarkable improvement in barrier property could be obtained, however, with the addition of TEOS more than 0.04 mol, the barrier property was dramatically reduced because of phase separation and micro-crack formation on the film surface.