• Journal of Radiation Industry
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• v.5 no.3
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• pp.197-202
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• 2011

In this study, an Ag-polyaniline-silica (Ag-PANI-silica) nanoparticle was evaluated as a radioisotope carrier. An Ag-PANI-silica nanoparticle was incubated in the $^{125}I$ solution for a duration of 24 hr to test its radioisotope absorptivity. During the incubation, radioactivity of the nanoparticle was measured at 3, 6, 12, and 24 hr. After a 24 hr incubation, $^{125}I$-Ag-PANI-silica nanoparticle was incubated in a fresh saline for a duration of 48 hr to check its stability. Additionally, the $^{125}I$-Ag-PANI-silica nanoparticle was injected to the ICR mouse to investigate its in-vivo distribution characteristics. The $^{125}I$ absorption yield of the Ag-PANI-silica nanoparticle was higher than 95% after a 6 hr incubation period in the $^{125}I$ solution. And $^{125}I$-Ag-PANI-silica was stable for 48 hr at 80% yield at room temperature. The SPECT/CT image of a mouse that received $^{125}I$-Ag-PANI-silica complex showed that the $^{125}I$-Ag-PANI-silica complex was distributed in the lung, stomach and thyroid at 30 min post injection. From these results, the Ag-PANI-silica nanoparticle has good radio-iodine carrying property and can be applicable for the purpose of diagnosis and therapy.

• Current Optics and Photonics
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• v.6 no.6
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• pp.521-549
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• 2022

Fiber lasers have made remarkable progress over the past three decades, and they now serve far-reaching applications and have even become indispensable in many technology sectors. As there is an insatiable appetite for improved performance, whether relating to enhanced spatio-temporal stability, spectral and noise characteristics, or ever-higher power and brightness, thermal management in these systems becomes increasingly critical. Active convective cooling, such as through flowing water, while highly effective, has its own set of drawbacks and limitations. To overcome them, other synergistic approaches are being adopted that mitigate the sources of heating at their roots, including the quantum defect, concentration quenching, and impurity absorption. Here, these optical methods for thermal management are briefly reviewed and discussed. Their main philosophy is to carefully select both the lasing and pumping wavelengths to moderate, and sometimes reverse, the amount of heat that is generated inside the laser gain medium. First, the sources of heating in fiber lasers are discussed and placed in the context of modern fiber fabrication methods. Next, common methods to measure the temperature of active fibers during laser operation are outlined. Approaches to reduce the quantum defect, including tandem-pumped and short-wavelength lasers, are then reviewed. Finally, newer approaches that annihilate phonons and actually cool the fiber laser below ambient, including radiation-balanced and excitation-balanced fiber lasers, are examined. These solutions, and others yet undetermined, especially the latter, may prove to be a driving force behind a next generation of ultra-high-power and/or ultra-stable laser systems.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.1
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• pp.13-22
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• 2022

In this study, we investigated the water quality and fish community of the Gudam Wetland, a riverine wetland in the middle-upper reaches of the Nakdong River, during March-October 2020. The main results were as follows: average annual flow rate: 45.0±23.7 m³/s, flow velocity: 0.4±0.3 m/s, water depth: 1.4±0.4 m, water temperature: 17.5±0.8℃, pH: 7.8±0.2, electrical conductivity: 121.6±19.0 ㎲/cm, dissolved oxygen concentration: 11.4±0.9 mg/L, suspended solids concentration: 3.8±2.0 mg/L, and the water quality was classified as Ia (very good). A total of 754 individual fish belonging to 4 orders, 7 families, and 19 species were investigated. Cyprinidae was the dominant group, with 13 species. The dominant species was Zacco platypus (39.3%), followed by Pseudogobio esocinus (17.5%). There were 8 (42.1%) endemic Korean species and 1 exotic species, Micropterus salmoides. Four species were carnivores, six were insectivores, and nine were omnivores. Regarding tolerance to environmental changes, 6 species were tolerant, 11 had intermediate tolerance, and 2 were sensitive. Fish community analysis revealed dominance of 0.57, diversity of 2.04, evenness of 0.69, and richness of 2.72, indicating a diverse and stable fish community. The fish assessment index showed that the assessment class was B (average 62.5), which was higher than that of major streams of the Nakdong River (class C). For sustainable conservation of the Gudam Wetland, management strategies such as minimizing aggregate collection and preventing inflow of non-point pollutants are required.

• IMMUNE NETWORK
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• v.24 no.2
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• pp.18.1-18.12
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• 2024

Acute necrotizing encephalopathy (ANE) is a rare but deadly complication with an unclear pathogenesis. We aimed to elucidate the immune characteristics of H1N1 influenza virus-associated ANE (IANE) and provide a potential therapeutic approach for IANE. Seven pediatric cases from a concentrated outbreak of H1N1 influenza were included in this study. The patients' CD4⁺ T cells from peripheral blood decreased sharply in number but highly expressed Eomesodermin (Eomes), CD69 and PD-1, companied with extremely high levels of IL-6, IL-8 in the cerebrospinal fluid and plasma. Patient 2, who showed high fever and seizures and was admitted to the hospital very early in the disease course, received intravenous tocilizumab and subsequently showed a reduction in temperature and a stable conscious state 24 h later. In conclusion, a proinflammatory cytokine storm associated with activated CD4⁺ T cells may cause severe brain pathology in IANE. Tocilizumab may be helpful in treating IANE.

• Journal of the Korean Geographical Society
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• v.28 no.1
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• pp.1-15
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• 1993

This research aims to investigate some respects of chemical weathering processes, espcially the amount of solute leaching, formation of clay minerals, and the chemical weathering rate of granite rocks under present climatic conditions. For this purpose, I investigated geochemical mass balance in a small catchment and the mineralogical composition of weathered bedrocks including clay mineral assemblages at four res-pective sites along one slope. The geochemical mass blance for major elements of rock forming minerals was calculated from precipitation and streamwater data which are measured every week for one year. The study area is a climatically and litholo-gically homogeneous small catchment($3.62Km^2$)in Anyang-shi, Kyounggi-do, Korea. The be-drock of this area id Anyang Granite which is composed of coarse-giained, pink-colored miner-als. Main rock forming minerals are quartz, K-Feldspar, albite, and muscovite. One of the chracteristics of this granite rock is that its amount of Ca and Mg is much lower than other granite rock. The leaching pattern in the weathering profiles is in close reltion to the geochemical mass balance. Therefore the removal or accumulation of dissolved materials shows weathering patterns of granite in the Korean peninsula. Oversupplied ions into the drainage basin were $H^+$, $K^+$, Fe, and Mn, whereas $Na^2+$, $Mg^2+$, $Ca^2+$, Si, Al and $HCO-3^{-}$ were removed from the basin by the stream. The consumption of hydrogen ion in the catchment implies the hydrolysis of minerals. The surplus of $K^+$ reflects that vegetation is in the aggravation stage, and the nutrient cycle of the forest in study area did not reach a stable state. And it can be also presumed that the accumulation of $K^+$ in the top soil is related to the surplus of $K^+$. Oversupplied Fe and Mn were presumed to accumulate in soil by forming metallic oxide and hydroxide. In the opposite, the removal of $Na^+$, Si, Al resulted from the chemical weathering of albite and biotite, and the amount of removal of $Na^+$, Si, Al reflected the weathering rate of the bedrock. But $Ca^2+$ and $Mg^2+$ in stream water were contaminated by the scattered calcareous structures over the surface. Kaolinite is a stable clay mineral under the present environment by the thermodynamical analysis of the hydrogeochemical data and Tardy's Re value. But this result was quite different from the real assemblage of clay miner-als in soil and weathered bedrock. This differ-ence can be explained by the microenvironment in the weathering profile and the seasonal variation of climatic factors. There are different clay forming environments in the stydy area and these differences originate from the seasonal variation of climate, especially the flushing rate in the weathering profile. As it can be known from the results of the analysis of thermodynamic stability and characteristics of geochemical mas balance, the climate during winter and fall, when it is characterized by the low flushing rate and high solute influx, shows the environmental characteristics to from 2:1 clay minerals, such as illite, smectite, vermiculite and mixed layer clay minerals which are formed by neoformation or transformation from the primary or secondary minerals. During the summer and spring periods, kaoli-nite is a stable forming mineral. However it should consider that the other clay minerals can transformed into kaolinite or other clay minerals, because these periods have a high flushing rte and temperature. Materials which are directly regulated by chemical weathering in the weathered bedrock are $Na^+$, Si, and Al. The leaching of Al is, however, highly restricted and used to form a clay mineral, and that of Si falls under the same category. $Na^+$ is not taked up by growing veget ation, and fixed in the weathering profile by forming secondary minerals. Therefore the budget of $Na^+$ is a good indicator for the chemical weathering rate in the study area. The amount of chemical weathering of granite rocks was about 31.31g/$m^2+$/year based on $Na^+$ estimation.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.492-497
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• 2015

VOCs (Volatile Organic Compounds) are generally generated in the painting process, or at the company and laundry where use organic solvents. The VOCs consist of various hydrocarbons and has low calorific value due to its dilution with atmospheric air. Therefore, the VOCs are difficult to burn by a conventional fuel combustor. In this study, a novel plasma dump combustor was proposed for the treatment of low calorific VOC gases. This combustor was designed a combination of the characteristics in a plasma burner, a dump combustor and a 3D matrix burner. The combustor has good structure for maintaining enough residence time and reaction temperature for stable flame formation and VOC destruction. For investigating the performance characteristics of the plasma dump combustor, an experiment was achieved for VOC feed rate, VOC injector position, etc. Toluene was used as a surrogate of VOC. The novel combustor gave better performance than a conventional combustor, showing that VOC destruction rate and energy efficiency were 89.64% and 12.27 kg/kWh respectively, at feeding rate of 450 L/min of VOC of 3,000 ppm of toluene concentration.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.6-12
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• 1998

To extract insoluble proteins and to improve functional properties of abolished proteins, a protease producing Aspergillus sp. MS-18 was isolated from soil. The enzyme was purified and its enzymological characteristics were investigated. It was found that production of protease reached to the maximum when the wheat brae medium containing, 3% arabinose, 0.5% polypepton, 0.1% $(NH_4)_2SO_4$ and 0.2% magnesium chloride was cultured for 3 days. Protease was purified 16.9 folds after ion exchange chromatography and gel filtration and the specific activity was 340.4 unit/mg. Purified enzyme was confirmed as a single band by the polyacrylamide gel electrophoresis. The molecular weight of protease was estimated to be 30,000. Crystalization form of purified protease was a stick shape with rounding edges. The optimum pH and temperature for the protease activity were 9.0 and $60^{\circ}C$, respectively. The enzyme was stable in pH 7.0-12.0 at $50^{\circ}C$. The activity of purified enzyme was inhibited by $Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$ and $Pb^{2+}$, whereas it was activited by $Na^+$, $Mg^{2+}$ and $Mn^{2+}$. The activity of the protease was inhibited by the treatment with ethylenediaminetetraacetic acid and phenylmethane sulfonyl fluoride. The result suggests that the purified enzyme is a serine protease with metal ion at active site. Km and Vmax of purified protease were $29.33\;{\mu}mole/L$ and $5.13\;{\mu}g/min$, respectively.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1008-1014
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• 2012

The amount of domestic carbon dioxide emissions is more than 600 million tons/year. The emitted $CO_2$ should be captured and stored, however, suitable storage sites have not been found yet. A lot of researches on the conversion of captured carbon dioxide to useful carbon source have been conducted. The purpose of this study is to convert stable carbon dioxide to useful resources using less energy. For this purpose reducing gas and metallic oxide (activator) are required. Hydrogen was used as reducing gas and cobalt ferrite was used as activator. Considering that activator has different physical properties depending on synthesis methods, activator was prepared by hydrothermal synthesis and solid method. Decomposition characteristics of carbon dioxide were investigated using synthesized powders. Temperature programmed reduction/oxidation (TPR/TPO) and thermogravimetric analyzer (TGA) device were used to observe the decomposition characteristics of carbon dioxide. Activator prepared by solid method with 5 and 10 wt% CoO content showed an excellent performance. In TGA experiments with samples prepared by the solid method, reduction by hydrogen was 29.0 wt% and oxidation by $CO_2$ was highest in 27.5 wt%. 95% of adsorbed $CO_2$ was decomposed with excellent oxidation-reduction behaviors.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.34-39
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• 2015

This study confirmed the characteristics of hydrogen production according to electrode materials by producing non-diaphragm alkaline water electroanalyzer that can be controlled at medium temperature to produce hydrogen. As a result of the electrochemical characteristics by electrode material ($IrO_2/Ti$, $RuO_2/Ti$, Ti), the highest efficiency was found in $RuO_2/Ti$, as a result of hydrogen production experiment by electrolyte concentration, electrolyte concentration has a tendency to be proportional to hydrogen production and the condition of 30% KOH showed the highest hydrogen production as $118.9m^3/m^3/day$. In the experiment that confirmed hydrogen production according to electrode materials, in case of combination of anode ($IrO^2/Ti$) and cathode ($RuO^2/Ti$), it was $157.55m^3/m^3/day$ that showed a higher hydrogen production by around 6.97% than that of $IrO^2/Ti$ and cathode. It is presumed that the improvement of electrochemical activation of DSA electrode increases hydrogen production and influences the improvement of durability compared to the former electrode so that it enables stable alkaline water electrolysis.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1143-1149
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• 2003

To elucidate a method of preventing dental caries, strains producing lytic enzymes were isolated and their characteristics were investigated. Among 5,00 alkalophilic strains isolated from soil, 22 strains showed lytic activity against Streptococcus mutans. Strain No. 4830, with the highest lytic activity, was selected for further study. Strain 4830 showed 94% sequence homology with the 16S rDNA sequence of Bacillus alcalophilus, but it was concluded to be different from Bacillus alcalophilus because of its biochemical characteristics. The strain was named Bacillus sp. 4830. The lytic enzyme from Bacillus sp. 4830 was purified by ethanol precipitation and CM-agarose column chromatography. The molecular weight of the lytic enzyme was determined to be 28 kDa by SDS-PAGE. The lytic enzyme was stable between pH 5.0 and pH 11 and up to $40^{\circ}C$. The optimal pH and temperature for the lytic activity was 9.0 and $50^{\circ}C$, respectively.