• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.526-529
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• 2002

Various fluoride films on a glass substrate were prepared and characterized in order to determine the best seed layer for a microcrystalline silicon (${\mu}c$-Si) film growth. Among the various group-IIA-fluoride systems, the $CaF_2$films on glass substrates illustrated (220) preferential orientation and a lattice mismatch of less than 0.7% with Si. $CaF_2$ films exhibited a dielectric constant between $4.1{\sim}5.2$ and an interface trap density ($D_{it}$ as low as $1.8{\times}10^{11}\;cm^{-2}eV^1$. Using the $CaF_2$/glass structure, we were able to achieve an improved ${\mu}c$-Si film at a process temperature of 300 $^{\circ}C$. We have achieved the ${\mu}c$-Si films with a crystalline volume fraction of 65%, a grain size of 700 ${\AA}$, and an activation energy of 0.49 eV.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.286-286
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• 2010

The lack of homogeneously sized single-walled carbon nanotubes (SWNTs) hinders their many applications because properties of SWNTs, in particular electrical conduction, are highly dependent on the diameter and chirality. Therefore, the preferential growth of SWNTs with predetermined diameters is an ultimate objective for applications of SWNTs-based nanoelectronics. It has been previously emphasized that a catalyst size is the one crucial factor to determine the CNTs diameter in chemical vapor deposition (CVD) process, giving rise to several attempts to obtain size-controllable catalyst by diverse methods, such as solid supported catalyst, metal-containing molecular nanoclusters, and nanostructured catalytic layer. In this work, diameter-controlled CNTs were synthesized using a nanostructured catalytic layer consisting of Fe/Al2O3/Si substrate. The CNTs diameter was controlled by structural modification of Al2O3 supporting layer, because Al2O3 supporting layer can affect agglomeration phenomenon induced by heat-driven surface diffusion of Fe catalytic nanoparticles at growth temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.248-248
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• 2016

We have investigated the crystallinity, preferential ordering, and interfacial stability of 1,4,5,8,9,11-hexaazatriphenylene-hexanitrile (HATCN) thin film interconnected with organic/inorganic multilayer. At the region close to the organic-organic interface, HATCN formed low crystalline order with substantial amorphous phase. As film growth continued, HATCN stacked with high crystalline phase. After a sputtering deposition of the indium zinc oxide (IZO) layer on top of HATCN/organic layer, the volume fraction of preferentially ordered HATCN crystals increased without any structural deterioration. In addition, the HATCN surface was kept quite stable by preserving the sharp interface between HATCN and sputtering deposited IZO layers.

• Journal of The Korean Association For Science Education
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• v.15 no.2
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• pp.158-163
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• 1995

The 40th Annual Southern Arizona Regional Science and Engineering Fair was analyzed in terms of contents of exhibits and research methods. Elementary school students like to choose first, biology; secondly. physics; thirdly, chemistry; fourthly. consumer science; fifthly, S.T.S; sixthly. earth science area topics. Chemistry area topics are 20 %, which are much more than rates appeared in American elementary science textbooks. Elementary school students like topics such as pollutions, energy saving materials and characteristics/selection of products required in every-day life. In the most preferential area, biology, students do experiments or survey about plants growth, microbiology, learning/behavior of animals, health/exercise, which are reconcile with the analysis of American elementary science contents.

• Korean Journal of Materials Research
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• v.17 no.1
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• pp.56-59
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• 2007

Recently, requirement for the ultra thin copper foil increases with smaller and miniaturized electronic components. In this study, we evaluated the surface morphology, crystal phase ana surface roughness of the copper film electrodeposited by pulse method without using additives. Homogeneous and dense copper crystals were formed on the titanium substrate, and the optimum condition was 25% duty cycle. Moreover, the surface roughness(Ra), $0.295{\mu}m$, is the smallest value in this condition. It is thought that this copper foil is good for electromigration inhibition due to the preferential crystal growth of Cu (111)

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.3-6
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• 2000

Liquid-liquid phase separation due to the very different density and composition occurs when the hypermonotectic alloys are solidified on the ground. Besides this, other factors such as preferential wetting and coalescence make it difficult to get uniform microstructures during the directional solidification of hypermonotectic alloys. Therefore a few novel solidification methods to get rid of such a nonuniformity have been reviewed and the recent experimental work using ultrasonic energy in conjunction with directional solidification has been presented. The uniformly solidified structures have been obtained when the ultrasonic of 20kHz applied to transparent organic system, Succinonitrile-Glycerol, varying ultrasonic amplitude and composition etc.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.242-243
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• 2005

The SrS:Ag, Cl thin films have been grown by the hot wall technique with S furnace placed on the outside of the growth chamber in order to investigate the crystallographic and optical characteristics. The XRD patterns indicate a strongly preferential orientation in the [200] direction. The PL spectrum has an emission peak of about 398nm which is assigned by the transition from $4d^{95}s^1$ to $4d^{10}$ of$Ag^+$ center.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.329-334
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• 1992

It has been shown that the application of hydrostatic pressure during superplastic forming of 8090A1 can prevent the cavitaiton normally encountered at atmospheric pressure and cavity growth rate factor .eta. in the plane strain state is greater than that in the equibiaxial stress state. .eta. value shows some difference compared to the theoretical value, which seems to be due to the continuous nucletion and coalescence of voids during superplastic deformation. Scatter of measured data of cavity volume fraction seems to be on preferential nucleation of viods on non-uniformly distributed second phase particles in the deforming matrix.

• Journal of Korea Foundry Society
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• v.24 no.2
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• pp.79-84
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• 2004

In this study, the electromagnetic vibration is adopted for modifying eutectic Si phase and reducing its size. The higher the current density and frequency of electromagnetic vibration(EMV), the finer the size of eutectic Si phase. The tensile strength and elongation of EMVed alloy were highly improved. Measured twin probability of EMVed alloy at a frequency of 1000 Hz was approximately six times as high as that of the normal alloy. The mechanism for the increase in twin density due to EMV during solidification could be supposed from the fact that the preferential growth along <112> in silicon was suppressed by preventing Si atom from attaching to the growing interface of Si phase and by changing the solid/liquid interfacial energy of silicon. According to the result of UTS test, because of modification of eutectic Si, UTS and elongation are highly increased.

• Corrosion Science and Technology
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• v.5 no.6
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• pp.189-195
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• 2006

Effects of tungsten (W) on the precipitation kinetics of secondary phases and the associated resistance to pitting corrosion of 25%Cr duplex stainless steels were investigated through microstructural and electrochemical noise analyses. With the partial substitution of W for Mo in duplex stainless steel, the potential and current noises of the alloy were significantly decreased in chloride solution due to retardation of the ${\sigma}$ phase precipitation. The preferential precipitation of the $\chi$ phase in the W-containing alloy during the early period of aging contributed to retarding the precipitation of the $\sigma$ phase by depleting W and Mo along grain boundaries. In addition, the retardation of the nucleation and growth of the $\sigma$ phase in the W-containing alloy appears to be attributed to the inherently low diffusivity of W compared with that of Mo.