• Journal of The Korean Astronomical Society
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• v.39 no.1
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• pp.9-17
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• 2006

In an attempt to investigate star formation activity and statistical properties of clumps of high Galactic latitude clouds (HLCs), we mapped the Polaris Flare region, PF121.3+25.5, in $^{12}CO\;and\;^{13}CO$ J = 1 - 0 using SRAO 6-m telescope and also observed its 12 $^{13}CO$ peak positions in CS J = 2 - 1 with TRAO 14-m telescope. $^{13}CO$ integrated intensity map shows clearly its clumpy structure and the locations of clumps well agree with $^{12}CO$morphology. CS line is not detected toward the 12 $^{13}CO$ peak positions, so we can conclude there are no dense $(\sim10^4\;cm^{-3})$ in this region. We decomposed 105 clumps from $^{13}CO$ map using GAUSSCLUMPS algorithm. The mass of clumps ranges from $7.8\;M_{\odot}\;to\;7.4{\times}10^{-2}\;M_{\odot}$ with a total mass of $66.4\;M_{\odot}$ The mass spectrum follows a power law, dN/dM ${\propto}\;M^{-\alpha}$ with a power index of ${\alpha}=1.91{\pm}0.13$. The virial masses of clumps are in the range of $10{\sim}100M_{LTE}$ and so these clumps are considered to be gravitationally unbound.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1200-1203
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• 2009

A solution processed polymer tandem cell has been fabricated by using the organic layer coated crystalline $TiO_2$ nanoparticle inter layer. The highly dispersive OL-$TiO_2$ has several advantages in terms of excellent film forming property, crystallinity, optical transparency, and well defined chemical composition. The surface morphology of the $TiO_2$ thin film was found to play a crucial role in the performance of the polymer tandem cell. The stability of the tandem cell, utilizing dense $TiO_2$ nanoparticles inter layer, was superior to the stability of the single junction cell.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.45-49
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• 2014

Well-crystallized $BaSi_2O_5:Eu^{2+}$ phosphor films were synthesized by heat treatment of spin-coated BaO:Eu on $SiO_2$ glass. We investigated luminescence-structure properties of these phosphor films as a function of heat-treatment temperature. From x-ray diffraction patterns, our $BaSi_2O_5:Eu^{2+}$ phosphor films revealed that (111)- and (204)-crystal planes of $BaSi_2O_5$ crystal were dominantly increased with an increase of heat-treatment temperature. Photoluminescence intensities of $BaSi_2O_5:Eu^{2+}$ phosphor films were increased with amount of these crystal planes. It can be explained that $Eu^{2+}$ ions were stably occupied at specific crystal orientation of $BaSi_2O_5$ crystal, enhancing the luminescent intensities of $BaSi_2O_5:Eu^{2+}$ phosphor films. In addition, our $BaSi_2O_5:Eu^{2+}$ phosphor films had transmittance of 70% at 510 nm,.due to the dense morphology and specific crystallinity of $BaSi_2O_5:Eu^{2+}$ phosphor films.

• Journal of Plant Biology
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• v.30 no.4
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• pp.257-266
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• 1987

Investigation on the ability of nitrogen usage by N2-fixing Nostoc muscorum and cultured tobacco cells when they were associately cultured on nitrogen-free media was carried out. Also, effect of polyamines on the associated cultured condition was carried out. In addition, morphological changes of N. muscorum and cultured tobacco cells in associate culture were observed to detect the possibility of induction of nitrogen fixing ability on cultued plant cells. The activity of nitrogenase increased markedly when N. muscorum was grown exclusively on nitrogen-free media. When N. muscorum was cultured associately with cultured tobacco cells on nitrogen-free media containing polyamines, high activity was detected in 10-4 M spermine treated group. Investigation on the change of polyamine amounts showed two times increase in spermidine and eight times increase in spermine on a associate culture. These effects of associated culture were shown through morphological change such as dense loclization of N. muscorum around the cultured tobacco cells as well as inside the cells. These results indicate the viability of N. muscorum in cultured tobacco cells and possible induction of nitrogen fixation ability by symbiosis.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.87.2-87.2
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• 2011

We report our 110 ks Chandra observations of the supernova remnant (SNR) 0104-72.3 in the Small Magellanic Cloud (SMC). The X-ray morphology shows two prominent lobes along the northwest-southeast direction and a soft faint arc in the east. Previous low resolution X-ray images attributed the unresolved emission from the southeastern lobe to a Be/X-ray star. Our high resolution Chandra data clearly shows that this emission is diffuse, shock-heated plasma, with negligible X-ray emission from the Be star. The eastern arc is positionally coincident with a filament seen in optical and infrared observations. Its X-ray spectrum is well fit by plasma of normal SMC abundances, suggesting that it is from shocked ambient gas. The X-ray spectra of the lobes show overabundant Fe, which is interpreted as emission from the reverse-shocked Fe-rich ejecta. The overall spectral characteristics of the lobes and the arc are similar to those of Type Ia SNRs, and we propose that SNR 0104-72.3 is the first case for a robust candidate Type Ia SNR in the SMC. On the other hand, the remnant appears to be interacting with dense clouds toward the east and to be associated with a nearby star-forming region. These features are unusual for a standard Type Ia SNR. Our results suggest an intriguing possibility that the progenitor of SNR 0104-72.3 might have been a white dwarf of a relatively young population.

• Journal of the Korean institute of surface engineering
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• v.37 no.1
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• pp.5-12
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• 2004

The enhancement of adhesion for Cu film on polycarbonate (PC) surface with the $Ar/O_2$ gas plasma treatment and dc-bias sputtering was studied. The plasma treatment with this reactive mixture changes the chemical property of PC surface into hydrophllic one, which is shown by the variation of contact angle with surface modification. The micro surface roughness that also gives the high adhesive environment is increased by the $Ar/O_2$ gas plasma treatment. These results were observed distinctly from the atomic force microscopy (AFM). The negative substrate dc-bias effect for the Cu adhesion on PC was also investifated. Accelerated $Ar^{+}$ lons in sheath area of anode bombard the bare surface of PC during initial stage of dc bias sputtering. PC substrate. therefore, has severe roughen and hydrophilic surface due to the physical etching process with more activated functional group. As dc-bias sputtering process proceeds, morphology of Cu film shows better step coverage and dense layer. The results of peel test show the evidence of superiority of bias sputtering for the adhesion between metal Cu and PC.C.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.116-119
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• 2000

The advantage of plasma-sprayed coating is their good resistance against thermal shock due to the porous state of the coated layer with a consequently low Youngs modules. However, the existence of many pores with a bimodal distribution and a laminar structure in the coating reduces coating strength and oxidation protection of the base metals. In order to counteract these problems, there have been many efforts to obtain dense coatings by spraying under low pressure or vacuum and by controlling particle size and morphology of the spraying materials. The aim of the present study is to survey the effects of the HIP treatment between 1100 and 130$0^{\circ}C$ on plasma-sprayed oxide coating of A1$_2$O$_3$, A1$_2$O$_3$-SiO$_2$ on the metal substrate (type C18N10T stainless steel). These effects were characterized by phase identification, Vickers hardness measurement, and tensile test before and after HIPing, These results show that high-pressure treatment has an advantage for improving adhesive strength and Vickers hardness of plasma- sprayed coatings.

• Korean Journal of Materials Research
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• v.15 no.11
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• pp.717-721
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• 2005

Silica powders were synthesized using emulsion solution containing water, nonionic surfactant of Triton N-57, and cyclohexane. Silica powders were prepared at low cost using inexpensive starting material of sodium silicate and ammonium sulfate. Morphology, size and size distribution were observed and determined using SEM. The powder was identified as silica by FT-IR and XRD analysis. Particle size and size distributions were affected by concentration of reactants, reaction time, and concentration of surfactant. Particle size were increased with increasing concentration of reactants and particles became dense with increasing reaction time. As R value increased, tile particle size was increased, reached a certain value and then decreased again. The silica powders synthesized under optimum condition were spherical in shape, $0.8{\mu}m$ in average particle size, narrow in particles size distribution, and well dispersed.

• 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.

• Journal of the Korean institute of surface engineering
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• v.48 no.5
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• pp.205-210
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• 2015

NbN coatings were prepared by ICP (inductively coupled plasma) assisted magnetron sputtering from a Nb metal target in $Ar+N_2$ atmosphere at various ICP powers. Effect of ICP on the microstructure, crystalline structure and mechanical properties of NbN coatings was investigated by field emission electron microscopy, X-ray diffraction, atomic force microscopy and nanoindentation measurements. The results show that ICP power has a significant influence on coating microstructure, structure and mechanical properties of NbN coatings. With the increasing of ICP power, coating microstructure evolves from the columnar structure of DC process to a highly dense one. Crystalline structure of NbN coatings were changed from cubic ${\delta}$-NbN to hexagonal ${\beta}-Nb_2N$ with increase of ICP power. The maximum nano hardness of 25.4 GPa with Ra roughness of 0.5 nm was obtained from the NbN coating sputtered at ICP power of 200 W.