• Journal of the Korean Applied Science and Technology
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• v.19 no.2
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• pp.86-96
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• 2002

Oligomer type anionic surfactants(RmM-Na or RmD-Na} were synthesized from $C_{8}{\sim}C_{16}$ long chain alkylvinylether and maleic anhydride (or maleic diethylether). And also their fluorescent anionic surfactants (RmF- Na) were obtained from alkali neutralization which opens the lactone ring of the condensing materials produced by maleic anhydride alkylvinylether copolymer and 3-aminophenol. The measurement results for the surface active properties of water soluble oligomer type anionic surfactants with fluorescent structure (RmF-Na) exhibited a remarkable surface tension lowing property, foam breaking property, and a ernulsing power.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.380-385
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• 2004

The efficiency of complex slurry preparation route for developing the high performance SiC matrix of RS-SiCf/SiC composites has been investigated. The green bodies for RS-SiC materials prior to the infiltration of nw/ten silicon were prepared with various C/SiC complex matrix slurries, which associated with both different sizes of starting SiC particles and blending ratios of starting SiC and carbon particles. The characterization of RS-SiC materials was examined by means of SEM, TEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, process optimization methodology is also discussed. The flexural strength of RS-SiC materials greatly depended on the content of residual Si. The decrease of starting SiC particle size in the C/SiC complex slurry was effective for improving the flexural strength of RS-SiC materials.

• Korean Journal of Materials Research
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• v.24 no.1
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• pp.13-18
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• 2014

In order to clarify the effect of Nb addition on the ductile-brittle transition property of sintered TiC, TiC-10 mol% Nb composites were researched using a three-point bending test at temperatures from room temperature to 2020 K, and the fracture surface was observed by scanning electron microscopy. It was found that the Nb addition decreases the ductile-brittle transition temperature of sintered TiC by 300 K and increases the ductility. The room temperature bending strength was maintained at up to 1800 K, but drastically dropped at higher temperatures in pure TiC. The strength increased moderately to a value of 320MPa at 1600 K in TiC-10 mol% Nb composites, which is 40% of the room temperature strength. Pores were observed in both the grains and the grain boundaries. It can be seen that, as Nb was added, the size of the grain decreased. The ductile-brittle transition temperature in TiC-10 mol% Nb composites was determined to be 1550 K. Above 1970 K, yieldpoint behavior was observed. When the grain boundary and cleavage strengths exceed the yield strength, plastic deformation is observed at about the same stress level in bending as in compression. The effect of Nb addition is discussed from the viewpoint of ability for plastic deformation.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.669-674
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• 2020

Liquid-phase-sintered (LPS) SiC materials were briefly examined with their microstructure and mechanical property. Especially, effect of high-temperature exposure on the tendency of fracture toughness of LPS-SiC were introduced. The LPS-SiC was fabricated in hot-press by sintering powder mixture of sub-micron SiC and sintering additives of Al₂O₃-Y₂O₃. LPS-SiC represented dense morphology and SiC grain-growth with some amount of micro-pores and clustered additives as pore-filling. The strength of LPS-SiC might affected by distribution of micro-pores. LPS-SiC tended to decrease fracture toughness depending on increasing exposure temperature and time.

• KSBB Journal
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• v.27 no.5
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• pp.319-323
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• 2012

Vitamin C or L-ascorbic acid, an essential nutrient for humans with antioxidative property, was coated with natural wax to be used as functional additives for cosmetics. Coating of vitamin C was performed using carnauba wax and olive wax in self-designed reaction chamber for 60 min. The yield of coated vitamin C with carnawuba wax and olive wax were up to $94.6{\pm}1.2%$ and $82.5{\pm}1.4%$, respectively. The stability of the carnauba wax-coated vitamin C in the lotion was improved 17.8% than that of uncoated vitamin C during 30 day storage at $25^{\circ}C$. Color and the layer separation of the lotion added with the coated vitamin C showed better property than with the uncoated vitamin C. The coated vitamin C can be applied to cosmetic ingredients as a stable additive.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1682-1684
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• 2004

In this study, the surface properties of PET film were analyzed after plasma surface treatment. After plasma treatment of surface roughness and XPS were evaluated to analyze the chemical property, while the surface potential decay and surface resistivity was measured to analyze the electrical characteristic. When plasma discharge treatment was conducted for less than 10 minutes, the electrical insulating property was found to be improved through evaporation of low molecular weight materials and cleaning of surface. However, when the treatment was conducted for more than 10 minutes, the insulating property was decreased due to excessive discharge energy. Analysis of chemical characteristics showed that 10-minute treatment resulted in increase of C-O and O=C-O. However, when treated for more than 10 minutes, they were relatively decreased.

• Bulletin of the Korean Mathematical Society
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• v.47 no.5
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• pp.997-1000
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• 2010

We prove that the reduced free product of $k\;{\times}\;k$ matrix algebras over abelian $C^*$-algebras is not the minimal tensor product of reduced free products of $k\;{\times}\;k$ matrix algebras over abelian $C^*$-algebras. It is shown that the reduced group $C^*$-algebra associated with a group having the property T of Kazhdan is not isomorphic to a reduced free product of abelian $C^*$-algebras or the minimal tensor product of such reduced free products. The infinite tensor product of reduced free products of abelian $C^*$-algebras is not isomorphic to the tensor product of a nuclear $C^*$-algebra and a reduced free product of abelian $C^*$-algebra. We discuss the freeness of free product $II_1$-factors and solidity of free product $II_1$-factors weaker than that of Ozawa. We show that the freeness in a free product is related to the existence of Cartan subalgebras in free product $II_1$-factors. Finally, we give a free product factor which is not solid in the weak sense.

• Communications of the Korean Mathematical Society
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• v.32 no.1
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• pp.201-214
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• 2017

In this paper, we introduce and study notions of average chain transitivity, average chain mixing, total average chain transitivity and almost average shadowing property. We also discuss their interrelations.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.407-410
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• 2003

We will introduce our new concept deposition system for SMOLED manufacturing in this conference. This system is designed to deposit organic and metal material to downward to overcome the limit of substrate size and process tact time hurdle for OLED mass production, and is organized with organic deposition chamber, substrate pre-cleaning chamber, metal deposition chamber and encapsulation system. These entire process chambers are integrated with linear type substrate transfer system. We also compare our new SMOLED manufacturing system with conventional vacuum deposition systems, and show basic organic thin film property data, organic material deposition property data, and basic device property.

• Honam Mathematical Journal
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• v.39 no.1
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• pp.115-126
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• 2017

In this paper, we aim to prove certain common fixed point theorems for a pair of weakly compatible mappings satisfying (CLRg) (or (E.A)) property in the bicomplex valued metric spaces. We also provide some examples which support the main results here.