• Journal of Korean Society for Atmospheric Environment
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• v.29 no.4
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• pp.390-406
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• 2013

In Korea, photochemical air pollution has drawn public attention as one of the major environmental issues since 1990s. To abate ozone and air pollution, new legislation was enacted and regulation was reinforced in conjunction with basic researches. As a result, the air quality has been much improved in terms of primary pollutant such as CO and the occurrence of extremely high ozone concentration. In Seoul, on the other hand, concentrations of ozone and exeedance hours of its national standard have increased since 2005, which is intimately coupled with $NO_2$ variations. It indicates the need for further research at long-term bases to improve our understanding on complex processes determining ozone concentrations. In this paper, the characteristics of ozone variation was analyzed with 13-year measurement data obtained in Seoul. In addition, the previous studies and their main results were summarized that have been performed in association with photochemical air pollution in Korea over the last three decades.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.764-767
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• 2006

Ni/YSZ $(Y_2O_3-stabilized\;ZrO_2)$ composite as an electrode component for High Temperature Electrolysis (HTE) was fabricated by mechanical alloying method using Ni and YSZ powders. Characterization of the synthesized composite was investigated with various analysis tools, including XRD, SEM and PSA, and a self-supporting planar unit cell prepared with the Ni/YSZ composite was prepared to study the electrochemical reactions for the production of hydrogen. The Ni/YSZ cermet is composed of crystalline Ni and YSZ, in a sub-micro scale, and has an even distribution without aggregated particles. In addition, under an electrochemical reaction, the unit cell showed an $H_2$ evolution rate from steam of 14 Nml/min and $600mA/cm^2$ of current density at the electrode.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.198.2-198.2
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• 2016

Reactive oxygen and nitrogen species (RONS) can be generated by using non-thermal atmospheric pressure plasma jet which have profound biomedical applications [1, 2]. In this work, reactive oxygen species like hydroxyl radical (OH) are generated by using non-thermal direct plasma jet above water surface using Ar gas and their properties have been studied using ultraviolet absorption spectroscopy. OH radicals are found to be generated simultaneously with the discharge current with concentration of $2.7{\times}1015/cm3$ at 7mm above water surface while their persistence time have been measured to be $2.8{\mu}S$. In addition, it has been shown that plasma initiated ultraviolets play a major role to generate RONS inside water. Further works are going on to measure the temporal behavior of OH and $O2^*-$.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.693-698
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• 1996

Optimal cultural conditions were investigated for the maximal productivity of nucleoside oxidase and peroxidase from Flavobacterium meningosepticum. Sucrose and Polypepton were the best as a carbon source and a nitrogen source. Fe$^{2+}$, Fe$^{3+}$ and Cu$^{2+}$ increased the activities of the two enzymes and were essential in medium containing peptone as a nitrogen source. Nucleoside derivatives such as 2'-deoxyguanosine, 2'-deoxyadenosine, N$^{6}$ -methyladenosine and 1-methyladenosine were effective for the production of the two enzymes. Especially, the addition of N$^{6}$ -methyladenosine and 1-methyladenosine decreased cell growth, but increased the two enzyme activities. High level of oxygen also was an essential factor for formation and/or induction of these enzymes. From the summary of this study about optimal medium and environmental conditions, nucleoside oxidase was biosynthesized in proportion to peroxidase. These results suggested that the role of peroxidase should be degradation of H$_{2}$O$_{2}$ generated by nucleoside oxidase in the cell of Flavobacterium meningosepticum.

• Clean Technology
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• v.9 no.2
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• pp.57-61
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• 2003

A novel nitric acid-free desmut solution has been developed to remove smut, which is produced from a NaOH etching, on the surface of aluminum alloy metal in metal surface treatment processes. Comparing with the performance of 5% $HNO_3$ desmut solution, the mixed acid solution containing 2% $H_2O_2$, 0.5% HF, and 10% $H_2SO_4$ shows the same effect of smut removal for aluminum alloy samples of A16061 and A15052. To examine the surface alterations of the aluminum samples, in addition, the surface analysis is carried out with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA).

• Journal of Nutrition and Health
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• v.25 no.7
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• pp.597-607
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• 1992

The present study examined effects of caffeine on coronary circulation myocardial oxygen me-tabolism and calcium release in isolated perfused guinea pig hearts. Intracoronary caffeine({{{{ {10 }^{-5 } }}}}∼{{{{ { 10}^{-3 } }}}}M) was employed for 10 minutes to measure coronary perfusate flow(CF) and coronary vascular sresistance(CVR) at a constant coronary perfusion pressure of 80 cmH2O Perfusate myocardial oxygen consumption(MVO2) and percent oxygen extraction(%EC2) were calcula-ted. In addition calcium contents in both perfusate samples were measured to calculate calcium release in coronary venous effluent. Caffeine significantly decreased CF and increased CVR during 10 minutes of caffeine perfusion regardless of dose of caffeine perfused exhibiting time-response. While % EO2 was significantly enhanced with caffeine MVO2 was markedly reduced. The coronary venous perfusate pH dcreased during the perfusion with caffeine. These changes were consistent with caffeine-induced metabolic acidosis. Calcium release appeared to be dose-dependent and high dose of caffeine greatly increased venous calcium release even 2 minutes after perfusion with carffeine. These finding in dicate that caffeine produced coronary vasoconst-riction with increased calcium release in isolated perfused guinea pig hearts. Additionaly this vasoconstrictor response mignt be due tin part to the direct actions of caffeine.

• Journal of Ginseng Research
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• v.9 no.2
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• pp.154-162
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• 1985

We report a newassay method on the measurement of the catalase activity, whose utilzation value is considered to be remarkable in the field of plant biochemistry. We named this method as a De-Coupling method. The essence of de-coupling method is the separation between the enzyme reaction and the indicator reaction. The optimum condition of the enzyme reaction was found to be following: on addition of 1 ml of substrate (H2O2: 20mM) to the fixture of the crude extract of enzyme (volume: 0.2 ml) and the ammonium phosphate buffer (volume: 1.8 ml; 0.93 M phosphate, 1.6M NHB, 2.5 M methanol, pH 7.0). After 30, 60 and 90 seconds of the enzyme reactions are proceeded, the reactions are terminated by 25% of tai-chloro-acetate (final concentration of 5%), respectively. The precipitated materials by tai-chloro-acetate was removed by the centrifugation (2000g, 10minutes). Formaldehyde produced in the enzymatic reaction was reacted with 2ml of acetylacetone (60mM). The indicator reaction -(HANTSCH REAKT10N)- in which lutidine is formed, was proceeded for 60 minutes at $25^{\circ}C$.

• Composites Research
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• v.35 no.2
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• pp.98-105
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• 2022

In this study, polyvinyl alcohol (PVA)/graphene oxide (GO)/iron oxide (Fe₃O₄) magnetic microgels were prepared using a microfluidic approach and the dye adsorption capacity of the microgels was confirmed. The adsorption capacity (q_e) of the gels was evaluated by varying the dye concentration, pH, and contact time with the microgels. The dyes used in this work were methylene blue (MB), crystal violet (CV), and malachite green (MG), and microgels showed the highest adsorption capacity (191.1 mg/g) in methylene blue. The microgels exhibited the highest adsorption capacity in the dye aqueous solution at pH 10 due to the presence of atomic nitrogen ions (N⁺) on the dye molecules. The adsorption isotherm studies revealed that the Langmuir isotherm is the best fit isotherm model for the dye adsorption on the microgels, indicative of monolayer adsorption. The kinetic analysis exhibited that the pseudo-second order model fits better than the pseudo-first order model, confirming that the adsorption process is chemisorption. In addition, the magnetic microgels showed good reusability and recovery efficiency. It was confirmed that the adsorption capacity of the gels maintains more than 70% of the initial capacity after 5 times of cycle experiments.

• Textile Coloration and Finishing
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• v.14 no.1
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• pp.1-10
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• 2002

The aim of study was to elucidate dyeability and antimicrobial and antifungal activity of silk fabrics dyed with Sophora Radix extracts according to different mordants. Dyes were extracted from Sophora Radix using ethanol. Then, silk fabrics were dyed with extracts two times by post-mordanting method in which the extract was 60%(owf), the mordant was 3%(owf), L.R was 1:20, the temperature was $60~60^\circ{C}$, the time of dyeing was 60min., and the time of mordanting was 60min. The dyeability was evaluated by surface color, K/S values and durability of dye. The skin microorganisms used in this study was S. sureus, B. subtilis, S. epidermidis, P. acnes, P. aeruginosa, E coli, A. niger, C. albicans and T. mentatrophytes. The results are as follows; 1. When mordants were added, K/S value of silk dyed was not improved much and surface color was 2.2Y to 8.8Y in H(hue) value which indicated greenish yellow to raddish yellow 2. The color fastness tests to light, perspiration, dry-cleaning, rubbing, and stain fabric washing show 4~5th degree which were valuated excellent. The color fastness to fade washing was improved to 3~4th degree by addition of $K_2CrO_7$ mordants. 3. Antibacterial activity of silk dyed using no-mordant as well as mordants was excellent on S. aureus, B. subtilis, S.epidermidis and P.acnes, but showed poor antibacterial activities on P.aeruginosa and E.coli such as gram negative baterials 4. Antifungal activity of silk dyed with ethanol extracts was good on A.niger, C.candida and T.mentagrophytes. Especially, on T. mentagrophytes there was no growth of fungus during 72 gous in silk dyed mordanting with $SnCl_2\cdot{2H}_2O$.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.639-644
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• 2011

A simple and highly sensitive chemiluminescence method to determine norfloxacin (NFLX) has been proposed by measuring the chemiluminescence (CL) intensities using a flow injection (FI) system. The CL intensity of the luminol-$H_2O_2$ system is strongly enhanced by the addition of Cu (II) in alkaline condition. The CL intensity is substantially increased after the injection of NFLX into the luminol-$H_2O_2$-Cu (II) system. The enhancement effect is attributed to a catalytic effect of Cu (II) due to the interaction with NFLX which forms a complex with the catalyst. Under the optimal conditions, the sensitizing effect of the CL intensity is proportional to the concentration of NFLX in the range of $1.5{\times}10^{-9}-5.9{\times}10^{-7}molL^{-1}$ (r = 0.9994) with a detection limit ($3{\sigma}$) of $2.98{\times}10^{-10}molL^{-1}$. The proposed method had good reproducibility with the relative standard deviation (RSD, n = 5) of 1.6% for $1{\times}10^{-7}molL^{-1}$ of NFLX. The possible reaction mechanism of the CL reaction is also discussed. This method has been successfully applied for the determination of trace amount of NFLX in pharmaceutical preparations and serum samples.