• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2044-2046
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• 2000

A system to monitor the ion mass and charge-state as well as plasma potential value during plasma source ion implantation (PSII) has been developed. It was tested with 30-kV PI3D setup using alternatively hot cathode do (HC) and inductively coupled RF (ICP) discharge sources. The design and performance of the system will be described, and experimental results in nitrogen and argon plasmas produced by modular HC-ICP source will be discussed.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.803-808
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• 2006

The neutron induced nuclear cross section data for Ir-191 and Ir-193 were calculated and evaluated from unresolved resonance energy to 20MeV. The energy-dependent optical model potential parameters were determined based on the experimental data and applied up to 20MeV. A spherical optical model, a statistical model in an equilibrium energy region, and a multistep direct and multistep compound model in a pre-equilibrium energy region were used in the calculations. The direct capture model enhanced the fast neutron capture in the pre-equilibrium energy. The theoretically calculated cross sections were compared with the experimental data and the evaluated files. The calculations were found to be in good agreement with the experiment data. The evaluated cross section results were compiled with the ENDF-6 format. The fast energy results will be merged with the resonance parts to create a full evaluation library. The improvement of the neutron-induced cross section data will contribute to an increase in the efficiency of the production of Ir-192 as a radiation source.

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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• pp.80-92
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• 1994

The dynamic response characteristics of a floating ocean city are examined for presenting the basic data for the design of huge offshore structures supported by a large number of floating bodies in waves. The numerical approach which is accurate in linear system is based on combination of a three dimensional source distribution method, wave interaction theory and the finite element method of using the space frame element. The hydrodynamic interactions among the floating bodies are taken into account in their exact form within the context of linear potential theory in the motion and structural analysis. The method is applicable to an arbitrary number of three dimensional bodies having any individual body geometries and geometrical arrangement with the restriction that the circumscribed, bottom-mounted. Imaginary vertical cylinder for each body does not contain any part of the other body. The validity of this procedure was verified by comparing with experimental results obtained in the literature.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.858-862
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• 2001

The purpose of this research was to investigate the effects of nondigestible oligosaccharides (NDO) from red ginseng marc on the growth of Bifidobacterium spp. Red ginseng marc, a fibrous byproduct of ginseng extract from processing, was destarched by ${\alpha}$-amylase and amyloglucosidase treatment, and then treated with a commercial pectinase to produce NDO. The bifidogenic effects of NDO on B. adolescentis, B. animalis, B. breve, and B. longum were investigated in vitro. NDO significantly promoted the growth of Bifidobacterium spp. The growth, decrease of pH, and organic acid formation (acetate, lactate, formate) were markedly different among the species. B. adolescentis showed the best growth and produced the greatest amount of organic acids. When NDO was used as a carbon source in the cocultivation of Bifidobacterium spp. and Clostridium perfringens, the growth of Bifidobacterium spp. was not influenced by the existence of Cl. perfringens. The result strongly suggested that NDO from red ginseng marc could be used as a potential bifidogenic source.

• Transactions on Electrical and Electronic Materials
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• v.18 no.3
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• pp.176-179
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• 2017

Non-vacuum processing technology was used to produce $Cs_3Sb$ photocathodes on substrates and fabricate in-situ panel devices. Electrical properties of these panel devices were characterized by measuring anode current and charge dose as functions of devices operation time. An excitation light source with a 475 nm wavelength was used for photocathodes. Results showed that emission properties of these photocathode emitters depended heavily on the vacuum level of these devices and that $Cs_3Sb$ flat emitters had the potential of operating for a long lifetime with stable electron emission characteristics via re-cesiation process in the panel device. These features make $Cs_3Sb$ photocathodes suitable as flat emitters in panel device applications.

• Nuclear Engineering and Technology
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• v.30 no.6
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• pp.485-495
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• 1998

Migration characteristics of tracers in a rock fracture in a case of line-source and line-collection was studied. The fracture plane was discretized into a square mesh to which variable apertures were assigned. The spatially varying apertures of a fracture were generated using a geostatistical method, based on a given aperture probability density distribution and a specified spatial correlation length. The flow potential and pressure at each node were computed. Calculations showed that fluid flow occurs predominantly through a few preferred paths. Hence, the large range of apertures in the fracture gives rise to flow channeling. The solute transport was calculated using a particle tracking method. The migration plumes of tracer between injection line and withdrawal line are displayed in contour plots. The elution curves are shown to be controlled by the aperture density distribution and to be insensitive to statistical realization and spatial correlation length.

• Environmental Engineering Research
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• v.24 no.2
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• pp.271-278
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• 2019

Mass cultivation of microalgae is necessary to achieve economically feasible production of microalgal biodiesel. However, the high cost of nutrients is a major limitation. In this study, corncob extract (CCE) was used as an inorganic and organic nutrient source for the mass cultivation of Chlorella vulgaris (C. vulgaris). Chemical composition analysis of CCE revealed that it contained sufficient nutrients for mixotrophic cultivation of C. vulgaris. The highest specific grow rate of C. vulgaris was obtained at pH of 7-8, temperature of $25-30^{\circ}C$, and CCE amount of 5 g/L. In the analysis using various growth models, Luong model was found to be the most suitable empirical formula for mass cultivation of C. vulgaris using CCE. Analysis of biomass and production of triacyglycerol showed that microalgae grown in CCE medium produced more than 17.23% and 3% more unsaturated fatty acids than cells cultured in Jaworski's Medium. These results suggest that growing microalgae in CCE-supplemented medium can increase lipid production. Therefore, CCE, agricultural byproduct, has potential use for mass cultivation of microalgae.

• Journal of Environmental Science International
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• v.28 no.2
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• pp.219-224
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• 2019

In this study, we evaluated the energy production from plant-microbial fuel cells using representative indoor plants, such as Scindapsus aureus and Clatha minor. The maximum power density of microbial fuel cell (MFC) using S. aureus ($3.36mW/m^2$) was about 2 times higher than that of the MFC using C. minor ($1.43mW/m^2$). It was confirmed that energy recovery is possible using plant-MFCs without fuel. However, further research is needed to improve the performance of plant-MFCs. Nevertheless, plant-MFCs have proved their potential as a novel energy source to overcome the limitations of the conventional renewable energy sources such as wind power and solar cells, and could be employed to a power source for the sensor in charge of the fourth industrial revolution.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.1-8
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• 2021

Human breast milk is a potential source of bacteria for the development of the intestinal microbiota of infants. Several species within the genera Lactobacillus and Bifidobacterium were demonstrated to shape the gut microbiota of infants. In this study, the bacterial diversity was investigated in the breast milk and feces of a mother-infant pair, and probiotic candidates were identified. Importantly, the novel L. gasseri EJL and B. breve JTL strains were isolated from breast milk and infant feces samples, respectively; their completed genome was resolved using de novo sequencing. In addition, the bacterial composition in the infant's feces at 1 week revealed the prevalence of Bifidobacterium and Streptococcus; a higher diversity was observed after 3 weeks. In particular, the abundance of Akkermansia was sharply increased at 7 weeks, further increasing thereafter, up to 15 weeks. Our results suggest that human breast milk and infant's feces are a source of probiotic candidates.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.663-671
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• 2022

The saccharification of cellulose and hemicellulose is essential for utilizing lignocellulosic biomass as a biofuel. While cellulose is composed of glucose only, hemicelluloses are composed of diverse sugars such as xylose, arabinose, glucose, and galactose. Sulfolobus acidocaldarius is a good potential candidate for biofuel production using hemicellulose as this archaeon simultaneously utilizes various sugars. However, S. acidocaldarius has to be manipulated because the enzyme that breaks down hemicellulose is not present in this species. Here, we engineered S. acidocaldarius to utilize xylan as a carbon source by introducing xylanase and β-xylosidase. Heterologous expression of β-xylosidase enhanced the organism's degradability and utilization of xylooligosaccharides (XOS), but the mutant still failed to grow when xylan was provided as a carbon source. S. acidocaldarius exhibited the ability to degrade xylan into XOS when xylanase was introduced, but no further degradation proceeded after this sole reaction. Following cell growth and enzyme reaction, S. acidocaldarius successfully utilized xylan in the synergy between xylanase and β-xylosidase.