• Nuclear Engineering and Technology
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• v.45 no.7
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• pp.827-838
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• 2013

Interaction layer growth between U-Mo alloy fuel particles and Al in a dispersion fuel is a concern due to the volume expansion and other unfavorable irradiation behavior of the interaction product. To reduce interaction layer (IL) growth, a small amount of Si is added to the Al. As a result, IL growth is affected by the Si content in the Al matrix. In order to predict IL growth during fabrication and irradiation, empirical models were developed. For IL growth prediction during fabrication and any follow-on heating process before irradiation, out-of-pile heating test data were used to develop kinetic correlations. Two out-of-pile correlations, one for the pure Al matrix and the other for the Al matrix with Si addition, respectively, were developed, which are Arrhenius equations that include temperature and time. For IL growth predictions during irradiation, the out-of-pile correlations were modified to include a fission-rate term to consider fission enhanced diffusion, and multiplication factors to incorporate the Si addition effect and the effect of the Mo content. The in-pile correlation is applicable for a pure Al matrix and an Al matrix with the Si content up to 8 wt%, for fuel temperatures up to $200^{\circ}C$, and for Mo content in the range of 6 - 10wt%. In order to cover these ranges, in-pile data were included in modeling from various tests, such as the US RERTR-4, -5, -6, -7 and -9 tests and Korea's KOMO-4 test, that were designed to systematically examine the effects of the fission rate, temperature, Si content in Al matrix, and Mo content in U-Mo particles. A model converting the IL thickness to the IL volume fraction in the meat was also developed.

• Journal of Magnetics
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• v.18 no.4
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• pp.400-404
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• 2013

Grain boundary diffusion technique with $DyH_3$ nanoparticles was applied to fabricate Dy-less sintered Nd-Fe-B permanent magnets with high coercivity. The magnetic properties and microstructure of magnets were systematically studied. The coercivity and remanence of grain boundary diffusion magnet were improved by 60% and reduced by 7% compared with those of the original magnet, respectively. Meanwhile, both the remanence temperature coefficient (${\alpha}$) and the coercivity temperature coefficient (${\beta}$) of the magnets were improved after diffusion treatment. Investigation shows that Dy is preferentially enriched as (Nd, Dy)$_2Fe_{14}B$ phase in the surface region of the $Nd_2Fe_{14}B$ matrix grains indicated by the remarkable enhancement of the magneto-crystalline anisotropy field of the magnet. As a result, the magnet diffused with a small amount of Dy nanoparticles possesses enhanced coercivity without remarkably sacrificing its magnetization.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.232-232
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• 2012

The doping of semiconducting elements is essential for the development of silicon quantum dot (QD) solar cells. Especially the doping elements should be activated by substitution at the crystalline sites in the crystalline silicon QDs. However, no analysis technique has been developed for the analysis of the activated dopants in silicon QDs in $SiO_2$ matrix. Secondary ion mass spectrometry (SIMS) is a powerful technique for the in-depth analysis of solid materials and the impurities analysis of boron and phosphorus in semiconductor materials. For the study of diffusion behaviour of B and P by SIMS, Si/$SiO_2$ multilayer films doped by B or P were fabricated and annealed at high temperatures for the activated doping of B and P. The distributions of doping elements were analyzed by SIMS. Boron found to be preferentially distributed in Si layer rather than the $SiO_2$ layer. Especially the B in the Si layers was separated to two components of an interfacial component and a central one. The central component was understood as the activated elements. On the other hand, phosphorus did not show any preferred diffusion.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1975-1979
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• 2011

The modification of a gas diffusion layer (GDL), a vital component in polymer electrolyte fuel cells, is described here for use in the electrochemical detection of antibody-antigen biosensors. Compared to other substrates (gold foil and graphite), mouse anti-rHBsAg monoclonal antibody immobilized on gold-coated GDL (G-GDL) detected analytes of goat anti-mouse IgG antibody-ALP using a relatively low potential (-0.0021 V vs. Ag/AgCl 3 M NaCl), indicating that undesired by-reactions during electrochemical sensing should be avoided with G-GDL. The dependency of the signal against the concentration of analytes was observed, demonstrating the possibility of quantitative electrochemical biosensors based on G-GDL substrates. When a sandwich method was employed, target antigens of rHBsAg with a concentration as low as 500 ng/mL were clearly measured. The detection limit of rHBsAg was significantly improved to 10 ng/mL when higher concentrations of the 4-aminophenylphosphate monosodium salt (APP) acting on substrates were used for generating a redox-active product. Additionally, it was shown that a BSA blocking layer was essential in improving the detection limit in the G-GDL biosensor.

• Journal of the Korean Society of Food Culture
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• v.34 no.4
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• pp.411-423
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• 2019

This study conducted qualitative research through in-depth interviews on the diffusion process of Korean food in accordance with the length of residence of Chinese students in Korea. As the analysis method, the qualitative analysis method such as NVivo12.0 was used, and the analysis was performed through word frequency, word cloud, and coding matrix. The images of taste of Korean food were revealed as 'Spicy', 'Sweet', and 'Light taste' by both short-term Chinese residents and long-term Chinese residents. The long-term Chinese residents showed their dissatisfaction with the institutional food, and they also pointed out the importance of the matter of cooking for quick adaptation to life in Korea. The long-term Chinese residents also thought of Korean food as 'High-fiber food', and this was influenced by the 'Less-oil' cooking method of Korean food, which is different from the cooking method of Chinese food. The length of residence was used as a main variable of this study, and it was one of the factors having positive effects on the diffusion of Korean food and acculturation. It would be difficult to generalize the results because this study used the convenience sampling method and snowball sampling.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.58-59
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• 2012

Surface hardening mechanism of H13 steel was investigated when ion niriding after shot peening process was applied. Severe plastic deformation induced nanocrystallized grains at surface region. Higher nitrogen concentration was achieved in ion nitrided specimen with shot peening treatment than in single nitrided specimen. The elemental mapping on chromium and nitrogen by TEM-EELs showed chromium dissolved in matrix enhanced bulk nitrogen diffusion at surface region. Higher nitrogen diffusion also caused lattice distortion. Nano-sized grains, higher nitrogen concentration, and lattice diffustion contributed to the surface hardening.

• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.366-371
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• 1999

The effect of VC addition on the microstructural evolution of Fe-TiC cermet has been investigated. The microstructures of the Fe-TiC varied with the amount of VC addition. The addition of 1wt% VC enhanced the instability of liquid-solid interface ; the dissolving interface showed round shape instead of facetted one which was ascribed to the increase of lattice mismatch between TiC and solid-solution carbide. in the speci-men with 10wt% VC the new set of solid-solution carbide grains of uniform and small size was formed in-side coarse TiC particles by diffusion induced recrystallizatin (DIR). With increasing the heat-treatment time fine recrystallized grains were dispersed homogeneously in the matrix and resulted in the increase in fracture strength.

• Korean Journal of Metals and Materials
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• v.50 no.9
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• pp.691-695
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• 2012

Calcium phosphate ceramic composites, consisting of hydroxyapatite(HA) and tricalcium phosphate (TCP), were fabricated by solid state sintering in order to investigate the effect of their initial compositions on microstructural evolutions and biocompatibility. All the sintered calcium phosphate ceramics exhibited almost full densification, while the grain growth of the composites increased with an increasing TCP content in the green body. The TCP phase transformed into a Ca-deficient HA phase during sintering via the diffusion of calcium ions from the HA phase into the TCP phase. The phases formed in the composites significantly affected the biocompatibility of the composites. The HA-matrix ceramic composites with TCP had a better cellular response than the pure HA ceramics, presumably due to the newly formed Ca-deficient HA.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1096-1101
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• 2008

Concrete is shown the time dependent behavior after placing. The time dependent behavior of normal strength concrete that is used usually in present, were already examined closely lots of parameters by several investigators. however, high strength concrete is that the material characteristics are not definite and the experimental data are lacking. So, The goal of this study is to propose the material characteristics models, and to develop the routine of the time dependent behavior above 60 MPa. The thermal conductivity, the specific heat, the moisture diffusion coefficient, and the surface coefficient are proposed the suitable models through the parametric study. The structural element is used the 8-node solid element. The matrix equation is developed considering the transient heat transfer and moisture diffusion theory. The application of the time dependent behavior is used the finite differential method.

• Journal of Wellbeing Management and Applied Psychology
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• v.5 no.3
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• pp.1-5
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• 2022

Purpose: The purpose of this study is to investigate whether wetland has antimicrobial activity on pathogenic bacteria in the toilet bowl. Research design, data and methodology: Air-dried mud obtained from "Jilmoe Bog" wetland was packed and dissolved in the autoclaved saline. Antimicrobial susceptibility was assessed against three Gram-negative bacteria using disk diffusion method and broth dilution method. Identification of specific bacterium presented in wetland supernatant was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Results: Incubation of three Gram-negative bacteria with wetland supernatant inhibited bacterial growth of the bacteria, otherwise increased prevalence of specific bacterium. It was confirmed that Pseudomonas putida was presented in wetland supernatant. Conclusions: The results presented in this study might provide the possibility to utilize wetland supernatant as a bioremediation of toilet bowl bacteria.