• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.787-792
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• 2012

The objective of this study was to investigate the proper concentration of D-xylose which is expected to reduce the GI (Glycemic index) value of sucrose in the human body. When subjects took a sucrose mixture containing 5% and 10% D-xylose, the blood glucose levels were lowered by approximately 27.5% and 25.9%, respectively, compared to those of sucrose. The GI values of sucrose mixtures containing 5% and 10% D-xylose were 49.3 and 50.4, respectively. The reduction in GI value was not dependent on the D-xylose concentration, as the GI value of sucrose mixture containing 5% D-xylose (XyloSugar) was similar to that of sucrose mixture containing 10% D-xylose (XyloSugar10). D-xylose is not only more expensive but also less sweet than sucrose. So, low concentration of D-xylose has the advantage in the price and taste. It was determined that the proper concentration of D-xylose expected to reduce GI value of sucrose was 5% (w/w).

• Journal of Applied Biological Chemistry
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• v.50 no.1
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• pp.17-21
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• 2007

1-C-(p-Hydroxyphenyl)-glycerol (1) was isolated and purified by column chromatography and recrystallization from the rhizome of Trichosanthes kirilowii, firstly in this species. Isolated compound showed inhibitory effects on the growth of five bacteria (Bacillus cereus, Escherichia coli, Streptococcus faecalis, etc) completely at the concentration higher than 10 ppm as well as delayed the growth of three bacteria (Bacillus substilis, Staphylococcus aureus, Pseudomonas aeroginosa) at the concentration of 25 ppm for 60 h. Moreover, this compound showed potent antioxidant activity against DPPH radical ($IC_{50}$ = 56.0 ppm)

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.701-706
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• 2003

A study on the electrosorption of U(VI) onto porous activated carbon fibers (ACFs) was performed to treat uranium-containing lagoon sludge. Effective U(Ⅵ) removal is accomplished when a negative potential is applied to the activated carbon fiber(ACF) electrode. For a feed concentration of 100mg/L, the concentration of U(VI) in the cell effluent is reduced to less than 1mg/L. The adsorbed uranium could be deserted from the ACF by passing a 1M NaCl solution through the cell and applying a positive potential onto the electrode. The regeneration of ACF from the cycling experiments was confirmed.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.41-41
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• 2011

The aims of this study were to examine the efficacy of phytochemicals of Rumex crispus as anti-oxidant and anti-browning agent. The bioactive properties of Rumex crispus as natural colorants were studied by total phenolic contents, DPPH radical scavenging, ABTS radical scavenging,lipid peroxidation, cell viability, singlet oxygen quenching and photoprotection effect. Among all of the results ($IC_{50}$: the concentration of various extracts required to exert 50% reducing effect), the higher activity of the extract was found in the ethyl acetate and butanol extracts. Anti-browning activity was evaluated by monitoring the change $L^*$, $a^*$, $b^*$ values and total color differences(${\Delta}E$). It was found that ethyl acetate and butanol extracts effectively inhibited browning in apple juice at a concentration below 0.3 mg/ml. Rumex crispus extracts used natural colorants could be of good resources as anti-oxidant and anti-browning agents. The results suggest that our study may contribute to the development of natural and functional materials with potential application to reduce oxidative damage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.63-76
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• 2016

Most previous studies found a positive relationship between the value of a firm and its R&D investments. This research measures the impact of the timescale of the R&D investment of a firm on its value using panel vector autoregression. By measuring the time required for R&D to impact the value of a firm, this study demonstrates that the lead time is an essential factor in the analysis of the effect of R&D investment on a firm's value. Our study finds that the length of the lead time varies according to the firm's size, industry concentration, and book to market ratio. Firms with a higher industry concentration show a shorter lead time. Also, firms with a larger size and higher book to market ratio generally show a shorter lead time.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.86-91
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• 2024

In this study, we investigated the effect of Na₂SiO₃ concentration on the Plasma Electrolytic Oxidation(PEO) film formation of Al6061 alloy. The morphology of the PEO films were examined by Optical Microscope(OM) and Scanning Electron Microscope(SEM). PEO film thickness increases as the Na₂SiO₃ concentration increases. The elemental analysis of PEO films was conducted using Dispersive X-ray Spectrometer(EDS). The cross-sectional elemental analysis result shows that the Si concentration tends to increase as the concentration of Na₂SiO₃ increases. X-Ray Diffraction(XRD) analysis was performed to confirm the degree of phase change according to Na₂SiO₃ concentration. In addition, Vickers hardness was measured to confirm the mechanical strength of the PEO film. As the concentration of Na₂SiO₃ increases, the hardness value also tends to increase.

• Journal of Technology Innovation
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• v.11 no.1
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• pp.79-97
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• 2003

R&D expenditure of Korean firms has been increasing drastically since 1980 and occupied 84% of total R&D expenditure in 1994. After 1994, however, the growth rate of industry R&D expenditure has dropped below single digit. R&D concentration rate of upper 20 companies declined from 61.9% in 1999 to 49.8% in 2001. The technology trade balance has diverged by 2.8 billion dollars in 2000 compared to around 0.3 billion dollars in 1985. We find several reasons on declining the industry R&D growth rate in Korea. First, we carefully say there might be an crowding out effect in increasing government R&D investment from Granger causality test between industry R&D and government R&D. Second, the decreasing benefit of tax credit since 1992 on industry R&D expenditure has caused the decrease of industry R&D growth rate. Third, the type of R&D cost becomes to similar to matured countries type of cost, which means the portion of capital expenditure has been decreased since late of 1980s. Therefore, industry R&D growth rate gets to saturation point. We draw several policy implications from the changing structure of business R&D of Korean company. Firstly, to stimulate industry R&D investment Korean government needs to strengthen tax credit policy. Secondly, to induce foreign direct investment Korean government needs to establish technology infrastructures and high quality of manpower. To utilize foreign technology resources Korean government need to introduce global R&D program executed by foreign scientist as an Project Leader.

• Journal of Animal Environmental Science
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• v.15 no.2
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• pp.107-114
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• 2009

Civil appeals on odor from swine barn have been increasing. This study was conducted to compile basic data of odor from swine barns as civil appeals on odor have been increasing. Odor was monitored from two gestating sow barns and the boundary of those barns in Suwon and Hwaseong city from June to November, 2008. Mean ammonia concentration measured at the boundary of A piggery in Suwon city was 0.9 ppm with occasional breaks of permissible limit (1.0 ppm). Mean concentrations of hydrogen sulfide and methyl mercaptan were 0.37 ppb and 0.01 ppb, which were lower than permissible limits of 20 ppb and 2 ppb, respectively. Mean ammonia concentration was 3.22 ppm and was maintained under 5.0 ppb. Ammonia concentration had increased since November when the barns were closed. Hydrogen sulfide and methyl mercaptan were lower than the permissible limits. Mean ammonia concentration measured at the boundary of B piggery in Hwaseong city was 16.3 ppm and steep increase of concentration was monitored after October when the barn was sealed up. Hydrogen sulfide and methyl mercaptan were 26.66 ppb and 7.45 ppb, respectively. In appropriate ventilation and raising environment would cause high ammonia concentration in swine barns. Emitted ammonia from barns and composting facilities were mixed, which would cause higher ammonia concentration on the boundary of barns. Hence improvement of raising environment, rapid manure treatment, and correct use of microbial preparation would be needed.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.113-118
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• 1986

Optimum temperature and pH of glutamine synthetase activity (E.C. 3.6.1.2.) of R. sphaeroides D-230 was $35^{\circ}C$ and 6.8, respectively. The adenylated state of GS in R. sphaeroides D-230 was stabilized by addition of 0.2mg/ml of cethyltrimethylammoniumbromide. Valine, histidine, proline, isoleucine, and lysine were good nitrogen source for the growth of R. sphaeroides D-230. The growth of R. sphaeroides D-230 in $N_2,\;NaNO_3\;or\;NH_4Cl$ as sole nitrogen source was lower than in any otherculture conditions. GS activity was inhibited, more or less, by various amino acid. THe relative inhibition rate of the enzyme by added 7mM arginine, $NH_4Cl,\;N_2,\;and\;NaNO_3$ was 63.8%, 26.79%, 6.24%, and 10.64%, drespectively. THe hydrogen evolution of R. sphaeroides D-230 grown in N-limited media was inhibited by 0.1mM MSX, irreversible GS inhibitor. GS activity was completely inhibited by 1.0mM MSX but ammonia released maximally at the same concentration of MSX. Ammonia release by added MSX was increased up to 1.0mM MS, but decreased above 1.0mM MSX. It is probably due to inhibition of nitrogenase actixity by MSX. Nitrogenase activity was not inhibited at low concentration of MSX. These results suggests that the inhibition of nitrogenase activity by ammonia is mediated by products of ammonia assimilation rather than by ammonia itself.

• Korean Journal of Medicinal Crop Science
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• v.20 no.6
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• pp.454-460
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• 2012

In this study, kaempferol and its rhamnosides (${\alpha}$-rhamnoisorobin, afzelin, kaempferitrin) were isolated electively by bioconversion technology from Hibiscus cannabinus L. leaves to evaluate the anti-wrinkles effects and anti-microbial effects. In order to evaluate anti-wrinkles activity, reduction of expression matrix metalloproteinase-1 (MMP-1) protein and proliferation/ pro-collagen production were investigated. Kaempferol and ${\alpha}$-rhamnoisorobin showed inhibition activity of MMP-1 generated to compared to positive control. In HaCaT cell proliferation assay, kaempferol and ${\alpha}$-rhamnoisorobin significantly promoted cell proliferation in a concentration-dependent manner. In addition, procollagen synthesis assays (by HDF-N cell) showd that TGF-${\beta}$ induced procollagen production and also, all four kinds of experimental significantly promoted procollagen synthesis in a concentration-dependent manner. Kaempferol and ${\alpha}$-rhamnoisorobin exhibited strong antimicrobial activities on five of microbes, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger.