• 한국세라믹학회지
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• 제35권8호
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• pp.890-893
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• 1998

• Journal of Welding and Joining
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• 제15권3호
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• pp.128-135
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• 1997

Reaction diffusion and formation of $Ni_3Al$phase with $L1_2$ structure have been studied in temperature range of 1432K to 1573K using the diffusion couple of (Ni-40, 5at%Al)/(Ni-14, 1at%Al) and (Ni-49, 2at%Al)/ (Nickel). The layer growth of Ni$_{3}$Al pyhase in the annealed diffusion couple was measured by optical microscope and electron probe microanalyzer (EPMA). The layer growth of $Ni_3Al$phase in diffusion zone obeyed the parabolic law without any indication of grain boundary effects. The layer growth of $Ni_3Al$phase in temperature range of 1423K to 1573K was mainly controlled by the volume diffusion mechanism. The rate of layer growth of $Ni_3Al$phase was found to be colsely related to the composition of intermetallic compound NiAl phase. The activation energy for layer growth of $Ni_3Al$phase was calculated to be 127kJ/mol.

• 산업식품공학
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• 제21권1호
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• pp.36-41
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• 2017

The release profiles of nisin from nisin-incorporating gel foods and the antimicrobial activities of the gels on the growth of Brochothrix thermosphacta in an aqueous system containing the gels have been investigated. A linear regression model was applied to determine the diffusion coefficient (D) for the diffusion of nisin in the gel. The antimicrobial activities of nisin released from 1, 2 and 3% (w/v) agar gels on the growth of B. thermosphacta in a broth medium with and without nisin were investigated. The D decreased from $1.2{\times}10^{-2}$ to $8.2{\times}10^{-3}$ and $6.4{\times}10^{-3}cm^2/s$ as the agar concentration in the gel increased from 1 to 2 and 3% (w/v), demonstrating the diffusion rate in the gels can be controlled by the agar concentration in gel. The agar gel incorporating nisin inhibited the B. thermosphacta growth in the broth medium by prolonging the lag phase. The growth inhibition was enhanced by the addition of nisin in the medium. The results of this study exhibited that the gel food is a feasible nisin delivery system with a controlled release achieved by the adjustment of agar concentration in the system, demonstrating the potential of nisin-incorporating gel for preserving particulate-containing drinks.

• 열처리공학회지
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• 제11권4호
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• pp.324-332
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• 1998

The grain growth characteristics of dual-phase (${\alpha}+{\gamma}$) containing high Cr-steel have investigate using ${\alpha}$-, ${\gamma}$-single phases and (${\alpha}+{\gamma}$)dual-phase of 12%Cr Steel. The heat treatment has performed at $1000-1200^{\circ}C$ for 1-100hr. The results are as follows : 1) The grain growth rate in (${\alpha}+{\gamma}$) dual phase was substantially slower than that of single grain. 2) The relation between mean grain radius $\bar{{\gamma}}$ and annealing time t is, in general, described as following equation : $$(\bar{{\gamma}})^n-(\bar{{\gamma}_o})^n=K_n{\cdot}t{\cdots}{\cdots}(1)$$ i) In the case of single phase of high Cr steel, Eq.(1) is described as $(\bar{{\gamma}})^2-(\bar{{\gamma}_o})^2=K_2{\cdot}t$ and the grain growth is controlled by boundary migration. ii) In dual phase, the grain growth needs diffusion of alloying elements because the chemical composition of ${\alpha}$- and ${\gamma}$- phases differs from each other. When the volume fraction of ${\alpha}$-, ${\gamma}$-phase was almost equal and ${\gamma}$-phase in the case of 80 and $90%{\gamma}$. Eq.(1) is described as $(\bar{{\gamma}})^3-(\bar{{\gamma}_o})^3=K_3{\cdot}t$ because the grain growth is controlled by volume diffusion iii) In the case of ${\gamma}$-rich phase (80 and $90%{\gamma}$), the grain growth of minor phase (10 and $20%{\alpha}$) is described as $(\bar{{\gamma}})^4-(\bar{{\gamma}_o})^4=K_4{\cdot}t$ because the boundary diffusion is predominent rather than volume diffusion.

• 한국분말재료학회지
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• 제4권3호
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• pp.214-221
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• 1997

The densification and grain growth mechanisms of $UO_{2+x}$ in $H_2$ and in $CO_2$ have been investigated. Uranium dioxide powder compacts were sintered at 1$700^{\circ}C$ in $H_2$ or at 110$0^{\circ}C$ in $CO_2$ for various times from 0.5 h to 16 h. The grain size and density of the specimens were measured. From the measured data, the mechanisms of the densification and grain growth were determined by use of available kinetic equations which express the relations between densification and grain growth. In both atmospheres, it has been found that the densification was controlled by the lattice diffusion and the grain growth by the surface diffusion of atoms around pores. It appears that the surface diffusivity as well as the lattice diffusivity increase considerably with the increase in O/U ratio in the specimen.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.43-45
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• 2003

The empirical model for predicting the prior austenite grain size in low-alloy steel weld HAZ was developed through examining the effect of alloying element. The test alloys were made by vacuum induction melting. Grain growth behaviors were observed and analyzed by isothermal grain growth test and subsequent metallography. As a result, it was found that the grain growth might be controlled by grain boundary diffusion and the empirical model for grain growth was presented.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
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• pp.192-199
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• 2003

Film growth of InP and GaAs using TMIn, TMGa, TBAs and TBP is numerically predicted and compared to the experimental results. To obtain exact thermal boundary conditions at the reactor walls, the gas flow and heat transfer are analyzed for full three-dimensional reactor including outer tube as well as the inner reactor parts. The results indicate that the exact thermal boundary conditions are important to get precise film growth rate prediction since film deposition is mainly controlled by the temperature dependent diffusion. The results also show that thermal diffusion plays an important role in the upstream region.

• The Korean Journal of Ceramics
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• 제5권2호
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• pp.99-103
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• 1999

Compressive creep of dense polycrystalline $BaTiO_3$, with average grain sizes of 19.3-52.4$\mu\textrm{m}$, has been investigated at 1100-$1300^{\circ}C$ in air or under controlled atmospheres $(10^2-10^5Pa \;O_2)$. Some cavity growth occurred during deformation because of non-steady-state damage accumulation in the form of cavitation. Comparison of the creep data of polycrystalline BaTiO3 with existing diffusivity and creep data for perovskite oxides suggested that deformation of polycrystalline $BaTiO_3$ was controlled by the extrinsic lattice diffusion of barium or titanium.

• 한국가시화정보학회지
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• 제6권2호
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• pp.45-50
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• 2008

It has been found that the colony size of bacteria grown on an agar plate decreases with increasing agar gel concentration. Evidenc from recent studies suggests that the bacterial colony dynamics is closely related with the mechanical properties of the substrate. We investigate whether bacterial growth on the agar substrate is controlled mostly by the nutrients' diffusion which is hindered more in porous medium than in solution. The number of bacterial cells in single colonies is found to be inversely correlated with agar concentration. High-resolution live cell imaging at the single bacterium level confirms that the bacterial growth rate is reduced with increasing agar concentration. There is a strong correlation between the slowed diffusion and the reduced number of cells in a high concentration of agar medium.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.2-2
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• 2011

Single-walled carbon nanotubes (SWNTs) have been considered as a promising candidate for nextgeneration electronics due to its extraordinary electrical properties associated with one-dimensional structure. Since diversity in electronic structure depends on geometrical features, the major concern has been focused on obtaining the diameter, chirality, and density controlled SWNTs. Despite huge efforts, the controlled synthesis of SWNTs has not been achieved. There have been various approaches to synthesize controlled SWNTs by preparation of homogeneously sized catalyst because the SWNTs diameter highly depends on catalyst nanoparticles size. In this study, geometrically controlled SWNTs were synthesized using designed catalytic layers: (a) morphologically modified Al2O3 supporting layer (Fe/Al2O3/Si), (b) Mo capping layer (Mo/Fe/Al/Si), and (c) heat-driven diffusion and subsequent evaporation process of Fe catalytic nanoparticles (Al2O3/Fe/Al2O3/Si). These results clearly revealed that (a) the grain diameter and RMS roughness of Al2O3 supporting layer play a key role as a diffusion barrier for obtaining Fe nanoparticles with a uniform and small size, (b) a density and diameter of SWNTs can be simultaneously controlled by adjusting a thickness of Mo capping layer on Fe catalytic layer, and (c) SWNTs diameter was successfully controlled within a few A scale even with its fine distribution. This precise control results in bandgap manipulation of the semiconducting SWNTs, determined by direct comparison of Raman spectra and theory of extended tight binding Kataura plot. We suggest that these results provide a simple and possible way for the direct growth of diameter, density, and bandgap controlled SWNTs by precise controlling the formation of catalytic films, which will be in demand for future electronic applications.