• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.548-548
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• 2012

Thermomechanical and surface chemical properties of composite films of poly(D, L-lactic-co-glycolic acid) (PLGA) were significantly improved by the addition of graphene oxide (GO) nanosheets as nanoscale fillers to the PLGA polymer matrix. Enhanced thermomechanical properties of the PLGA/GO (2 wt.%) composite film, including an increase in the crystallization temperature and reduction in the weight loss, were observed. The tensile modulus of a composite film with increased GO fraction was presumably enhanced due to strong chemical bonding between the GO nanosheets and PLGA matrix. Enhanced hydrophilicity of the composite film due to embedded GO nanosheets also improved the biocompatibility of the composite film. Improved thermomechanical properties and biocompatibility of the PLGA composite films embedded with GO nanosheets may be applicable to biomedical applications such as scaffolds.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.315-315
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• 2011

The ring formation and electronic properties of furan adsorbed on graphene layers grown on 6H-SiC(0001) has been investigated using atomic force microscopy (AFM), near edge X-ray absorption fine structure (NEXAFS) spectra for the C K-edge, and high resolution photoemission spectroscopy (HRPES). Moreover, we observed that furan molecules adsorbed on graphene could be used for chemical functionalization via the lone pair of electrons on the oxygen group, allowing chemical doping. We also found that furan spontaneously formed rings with one of three different bonding configurations and the electronic properties of the ring formed by furan on graphene can be described using by AFM, NEXAFS and HRPES, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.478-478
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• 2011

The thermomechanical and surface chemical properties of nanocomposite of poly( D, L-actic-co-glycolic acid) (PLGA) were improved significant due to concentration of graphene oxide (GO) nanosheets as nanoscale fillers to PLGA film. Thermomechanical properties of the PLGA/GO (2wt.-%.) nanocomposite were decreased crystallization and melting temperature, weight loss. The storage and loss moduli of the nanocomposite were enhanced by chemical bonding between the oxygenated functional groups of the GO nanosheets and the polymer chains in the PLGA matrix. Enhanced hydrophilicity of nanocomposite caused by embedded GO nanosheets also improved for good biocompatibility. Our findings indicate that thermomechanical properties and biocompatibility of nanocomposite embedded with GO nanosheets are attractive candidates for use in biomedical applications such as scaffolds.

• Journal of the Korean Graphic Arts Communication Society
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• v.19 no.1
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• pp.75-85
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• 2001

This study confirmed different results according to the molecular weight and pore properties of treated pulp. In this study the pre-treated enzyme material was increasing the beating speed compared with non-treated one. And it was observed that the change of freeness according to the combination ratio depended upon the pores size of pulp and that fibers became flexible owing to the physical deformation of fibers themselves through pre-treated enzyme increasing the flexibility of fibers to increase the contact area of fiber and thus resulting in the increase of specific surface area, the increase of fiber bonding strength and the increase of beating speed.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.57-62
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• 2009

N-Halamines are compounds which have covalent bonding between nitrogen and halogen. N-Halamine materials possess strong antimicrobial properties against wide spectrum of bacteria. The aim of this study is to prepare N-halamine membranes using m-aramid and poly(vinyl alcohol) (PVA). Surface characteristics using scanning electron microscope (SEM), pore size distribution, liquid permeability and mean pore size were measured to confirm feasibility as membrane. The results indicated that increased PYA portion up to 15% in the m-aramid/PVA blend resulted in improved pore size distribution, liquid permeability as well as mean pore size. Furthermore, antibacterial efficacy of the membranes after chlorination was confirmed and the results showed that bacteria in water were inactivated.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.70-75
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• 2015

Fasciclin 1 (FAS1) is an extracellular protein whose aggregation in cornea leads to visual impairment. While a number of FAS1 mutants have been studied that exhibit enhanced/decreased aggregation propensity, no structural information has been provided so far that is associated with distinct aggregation potential. In this study, we have investigated the structural and thermodynamic characteristics of the wild-type FAS1 and its two mutants, R555Q and R555W, by using molecular dynamics simulations and three-dimensional reference interaction site model (3D-RISM) theory. We find that the hydrophobic solvent accessible surface area increases due to hydrophobic core repacking in the C-terminus caused by the mutation. We also find that the solvation free energy of the mutants increases due to the enhanced non-native H-bonding. These structural and thermodynamic changes upon mutation contribute to understand the aggregation of these mutants.

• Journal of Korea Foundry Society
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• v.29 no.5
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• pp.198-203
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• 2009

In order to manufacture copper ultra fine wire used for bonding wire in integrated circuit package, continuous casting process, which can produce high purity copper rod with small cross section, and wiredrawing process have to be optimized to prevent wire brakeage during entire manufacturing process of fine wire. The optimum condition for producing copper rod with mirror surface has to established by investigation of the effects of several parameters such as withdrawal speed, superheat and rod diameter on grain morphology of the cast rod and on its drawing characteristics to fine wire. The purpose of this study is to propose the optimized process parameters in continuous casting process in order to produce cast rod without internal defects, and to predict microstructure orientation suitable for wire drawing process.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.89-90
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• 2000

A new technology realizing interconnection between Plastic Film LCDs panel and a driving circuit was developed under the processing condition of low temperature and pressure with ACFs developed for Plastic Film LCDs. The conduction failure of interconnection of the two resulted from elasticity, low thermal resistance and high thermal expansion of plastic substrates. Conductive particles with elasticity similar to the plastic substrate did not damaged a ITO electrode on plastic substrates, and low temperature and pressure process also did not deform the surface of plastic substrates. As a result highly reliable interconnection with minimum contact resistance was accomplished.

• The Korean Journal of Ceramics
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• v.3 no.3
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• pp.163-168
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• 1997

Most of heteroepitaxial $\beta$-SiC thin films have been successfully grown on Si(100) adapting a carburizing process, by which a few atomic layers of substrate surface is chemically converted to very thin SiC layer using hydrocarbon gas sources. Using an organo-silicon precursor, bis-trimethylsilymethane (BTMSM, [$C_7H_{20}Si_2$]), heteropitaxial $\beta$-SiC thin films were successfully grown directy on Si substrate without a carburized buffer layer. The defect density of the $\beta$-SiC thin films deposited without a carburized layer was as low as that of $\beta$-SiC films deposited on carburized buffer layer. In addition, void density was also reduced by the formation of self-buffer layer using BTMSM instead of carburized buffer layer. It seems to be mainly due to the characteristic bonding structure of BTMSM, in which Si-C was bonded alternately and tetrahedrally (SiC$_4$).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.12
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• pp.1011-1015
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• 2002

In this study, Au thin films were etched with a Cl$_2$/Ar gas combination in an inductively coupled plasma. The highest etch rate of the Au thin film was 3500 A/min at a Cl$_2$/(Cl$_2$+Ar) gas mixing ratio of 0.2. The surface reaction of the etched Au thin films was investigated using x-ray photoelectron spectroscopy (XPS) analysis. There is Au-Cl bonding by chemical reaction between Cl and Au. During the etching of Au thin films in Cl$_2$/Ar plasma, Au-Cl bond is formed, and these products can be removed by the physical bombardment of Ar ions[l].