• Carbon letters
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• v.10 no.3
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• pp.190-197
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• 2009

Various silanes, amino silane, vinyl silane, sulfur silane (TESPD), and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB) and CIIR/hard clay/CB compounds and they are investigated with respect to the vulcanization characteristics, the processability, and the mechanical properties. Comparing hard clay and soft clay filled compounds, hard clay (Suprex) filled system shows a higher die C tear than the soft clay (GK) filled one. The other properties (Mooney, extrusion torque/pressure, torque rise ($M_H-M_L$), modulus at 300%) are close to each other. Among various silanes, the ZS treated hard clay (Suprex) compound shows the highest mechanical property following hard clay(S)/vinyl silane(V) and soft clay(GK)/vinyl silane(V) compounds. The TESPD and the ZS effectively helps a formation of a strong 3-dimensional network structure between silica and CIIR via coupling reaction due to bifunctional nature of TESPD. In addition to that, the ZS added compounds show both a better processability and mechanical properties compared to the S2 ones at low concentration due to improved compatibility between zinc soap and CIIR matrix. Only the ZS added compound shows both improved processabilities (Mooney, Extrusion torque-& pressure) and improved mechanical properties (degree of crosslinking, elongation modulus, tear, and fatigue to failure counts) on both CIIR/hard clay/CB and CIIR/soft clay/CB compounds.

• BMB Reports
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• v.34 no.4
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• pp.347-354
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• 2001

$\alpha$-Glucosidase of an extreme thermophile, Thermus caldophilus GK24 (TcaAG), was purified 80-fold from cells to a homogeneous state and characterized. The enzyme exhibited optimum activity at pH 6.5 and $90^{\circ}C$, and was stable from pH 6.0 to 85 and up to $90^{\circ}C$. The enzyme had a half-life of 85 minutes at $90^{\circ}C$. An analysis of the substrate specificity showed that the enzyme hydrolyzed the non-reducing terminal unit of $\alpha$-1,6-glucosidic linkages of isomaltosaccharides and panose, $\alpha$-1,3-glycosidic bond of nigerose and turanose, and $\alpha$-1,2-glycosidic bond of sucrose. The gene encoding the TcaAG was cloned, sequenced, and sequenced in E. coli. The nucleotide sequence of the gene encoded a 530 amino acid polypeptide and had a G+C content of 68.4% with a strong bias for G or C in the third position of the codons (93.6%). A sequence analysis revealed that TcaAG belonged to the $\alpha$-amylase family. We suggest that this monomeric, thermostable, and broad-acting $\alpha$-glucosidase is a departure from previously exhibited specificities. It is, therefore, a novel $\alpha$-glucosidase.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.115-125
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• 2000

Three major hospitals with over 500 beds located in and near Seoul were surveyed for airbone microorganisms from February 1, 1998 to February 18, 1998. The purpose of the study was to identify and quantify microbiological organisms circulating in the air of three different areas in the hospitals. For the study, a RCS air sampler was utilized equipped with two different collection media, the agar strip GK-A for bacteria and the agar strip HS for fungi. The areas investigated were the intensive care unit (ICU) in the Department of internal medicine, the Newborns room in the Department of Obstetrics, and the microbiology laboratory. The results were as follows; 1. The average numbers of general microbiological particles collected on the agar strip GK-A media were $205CFU/m^3$, $232CFU/m^3$, and $128CFU/m^3$ in each hospitals. The highest concentration of $387CFU/m^3$ was found in the ICU of A hospital at 15:00 during the day. Further analysis of the collected bioaerosols by gram staining, revealed that there were gram positive cocci (89.5%), gram positive bacilli (7.2%), gram negative bacilli (2.8%), and fungi (0.5%), in descending order of frequency. 2. Ten different genes were identified from the agar strip GK-A. The most frequently identified organisms were: the Coagulase negative staphylococcus (55.0%), Micrococcus (21.4%), Enterococcus species(10.4%), and Bacillus species (7.2%). A series of antibiotics susceptibility test were conducted against the aforementioned four(4) organisms. Ninety percent of coagulase negative stapylococcus were sensitive to Penicillins. Pathogenic microbes isolated include: Staphylococcus aureus, Acinetobacter species, Klebsiella pneumonia, Klebsiella oxytoca, and Pseudomonas aeroginosa. 3 Although 56.8% of the microorganisms grown on the strip HS media for fungi could not be identified, some of them were successfully identified. The most frequently found fungi were Aspergillus (35.3%), Yeast or Molds (6.2%), and Penicillium (0.7%). Based on the results obtained from the study, it was concluded that some areas in the hospitals had abnormally high bioaerosol concentrations which could be attributed to human activity. Therefore, it is recommended that periodic assessments of indoor bioaerosols aiming to identify the possible sources should be conducted in order to maintain clean indoor environment in the hospitals.

• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.337-342
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• 2019

This letter describes the development of WRI (Wildfire Risk Index) using GDAPS (Global Data Assimilation and Prediction System) and satellite data, and its application to the Goseong-Sokcho and Gangneung-Donghae wildfires in April 4, 2019. We made sure that the proposed WRI represented the change of wildfire risk of around March 19 and April 4 very well. Our approach can be a viable option for wildfire risk monitoring, and future works will be necessary for the utilization of GK-2A products and the coupling with the wildfire prediction model of the Korea Forest Service.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.451-463
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• 2018

The empirical/statistical models to estimate the ground Particulate Matter ($PM_{2.5}$) concentration from Geostationary Ocean Color Imager (GOCI) Aerosol Optical Depth (AOD) product were developed and analyzed for the period of 2015 in Seoul, South Korea. In the model construction of AOD-$PM_{2.5}$, two vertical correction methods using the planetary boundary layer height and the vertical ratio of aerosol, and humidity correction method using the hygroscopic growth factor were applied to respective models. The vertical correction for AOD and humidity correction for $PM_{2.5}$ concentration played an important role in improving accuracy of overall estimation. The multiple linear regression (MLR) models with additional meteorological factors (wind speed, visibility, and air temperature) affecting AOD and $PM_{2.5}$ relationships were constructed for the whole year and each season. As a result, determination coefficients of MLR models were significantly increased, compared to those of empirical models. In this study, we analyzed the seasonal, monthly and diurnal characteristics of AOD-$PM_{2.5}$model. when the MLR model is seasonally constructed, underestimation tendency in high $PM_{2.5}$ cases for the whole year were improved. The monthly and diurnal patterns of observed $PM_{2.5}$ and estimated $PM_{2.5}$ were similar. The results of this study, which estimates surface $PM_{2.5}$ concentration using geostationary satellite AOD, are expected to be applicable to the future GK-2A and GK-2B.

• The Korean Journal of Zoology
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• v.31 no.1
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• pp.56-61
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• 1988

The taxonomic status of Moroco Jagowskii and M oxycephalus a pair of sibling species inhabiting in Korean fresh waters, has been unclear up to date. Recently a sympatric area of these species was found (Kang, 1987). The purpose of this study was to clarify their specific status by analysing specimens collected from the sympatric area of these species. Isozyme analysis and morphometric comparison were performed. Among 26 loci screened 6 loci (Aco, Est-2, E-X, Gk-3, Ipo, Me) showed fixed allelic difference between them and these loci could be used as genetic markers to distinguish them. Isozyme analysis indicates that no hybridization occurs and therefore it is assumed that isolating mechanism is completed and they are distinct species. The mean number of scales above lateral line (SAL) of M Jagowskii and M oxycephalus at sympatric area was 24.93 $\pm$1.95 and 17.33$\pm$0.72 respectively, and it seems as the result of character displacement. A finer microhabitat segregation between them is noticed. M oxycephalus is found along the effluent streams whereas M lagowskii is distributed mostly in the main stream at sympatric area.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.891-907
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• 2023

Compact Advanced Satellite 500-4 (CAS500-4) is scheduled to be launched to collect high spatial resolution data focusing on vegetation applications. To achieve this goal, accurate surface reflectance retrieval through atmospheric correction is crucial. Therefore, a machine learning-based atmospheric correction algorithm was developed to simulate atmospheric correction from a radiative transfer model using Sentinel-2 data that have similarspectral characteristics as CAS500-4. The algorithm was then evaluated mainly for forest areas. Utilizing the atmospheric correction parameters extracted from Sentinel-2 and GEOKOMPSAT-2A (GK-2A), the atmospheric correction algorithm was developed based on Random Forest and Light Gradient Boosting Machine (LGBM). Between the two machine learning techniques, LGBM performed better when considering both accuracy and efficiency. Except for one station, the results had a correlation coefficient of more than 0.91 and well-reflected temporal variations of the Normalized Difference Vegetation Index (i.e., vegetation phenology). GK-2A provides Aerosol Optical Depth (AOD) and water vapor, which are essential parameters for atmospheric correction, but additional processing should be required in the future to mitigate the problem caused by their many missing values. This study provided the basis for the atmospheric correction of CAS500-4 by developing a machine learning-based atmospheric correction simulation algorithm.

• Nutrition Research and Practice
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• v.11 no.3
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• pp.180-189
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• 2017

BACKGROUND/OBJECTIVES: Recent living condition improvements, changes in dietary habits, and reductions in physical activity are contributing to an increase in metabolic syndrome symptoms including diabetes and obesity. Through such societal developments, humankind is continuously exposed to metabolic diseases such as diabetes, and the number of the victims is increasing. This study investigated Cordyceps militaris water extract (CMW)-induced glucose uptake in HepG2 cells and the effect of CMW treatment on glucose metabolism. MATERIALS/METHODS: Colorimetric assay kits were used to determine the glucokinase (GK) and pyruvate dehydrogenase (PDH) activities, glucose uptake, and glycogen content. Either RT-PCR or western blot analysis was performed for quantitation of glucose transporter 2 (GLUT2), hepatocyte nuclear factor 1 alpha ($HNF-1{\alpha}$), phosphatidylinositol 3-kinase (PI3k), protein kinase B (Akt), phosphorylated AMP-activated protein kinase (pAMPK), phosphoenolpyruvate carboxykinase, GK, PDH, and glycogen synthase kinase 3 beta ($GSK-3{\beta}$) expression levels. The ${\alpha}-glucosidase$ inhibitory activities of acarbose and CMW were evaluated by absorbance measurement. RESULTS: CMW induced glucose uptake in HepG2 cells by increasing GLUT2 through $HNF-1{\alpha}$ expression stimulation. Glucose in the cells increased the CMW-induced phosphorylation of AMPK. In turn, glycolysis was stimulated, and glyconeogenesis was inhibited. Furthermore, by studying the mechanism of action of PI3k, Akt, and $GSK-3{\beta}$, and measuring glycogen content, the study confirmed that the glucose was stored in the liver as glycogen. Finally, CMW resulted in a higher level of ${\alpha}-glucosidase$ inhibitory activity than that from acarbose. CONCLUSION: CMW induced the uptake of glucose into HepG2 cells, as well, it induced metabolism of the absorbed glucose. It is concluded that CMW is a candidate or potential use in diabetes prevention and treatment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.283-288
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• 2019

In this paper, there is summarized the validation of ground test results through the telemetry acquired during on-orbit initial activation on solar-array drive assembly(SDA) of GK2A launched at Dec-5, 2018. Especially, the decision logic of SDA initial position and the compensation logic are validated and confirmed. The SDA initial position is needed when GK2A enter to geostationary orbit from transfer orbit and the compensation logic is for the accumulated position error due to the open-loop control. Up to now, it is normal operating. Also the periodic offset between the geostationary orbit and Sun position is found that it is not checked on design phase, and then the proper threshold value is applied.

• Journal of Life Science
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• v.9 no.1
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• pp.26-34
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• 1999

A thermostable pullulanase has been isolated and purified from Thermus caldophilus GK-24 to a homogeneity by gel-filtration and ion-exchange chromatography. The specific activity of the purified enzyme was 431-fold increase from the crude culture broth with a recovery of 11.4%. The purified enzyme showed $M_{r}$ of 65 kDa on denaturated and natural conditions. The pI of the enzyme was 6.1 and Schiff staining was negative, suggesting that the enzyme is not a glycoprotein. The enzyme was most active at pH 5.5. The activity was maximal at $75^{\cire}C$ and stable up to $95^{\cire}C$ for 30 min at pH 5.5. The enzyme was stable to incubation from pH 3.5 to pH 8.0 at $4^{\cire}C$ for 24hr. The presence of pullulan protected the enzyme from heat inactivation, the extent depending upon the substrate concentration. The activity of the enzyme was simulated by $Mn^{2+}$ ion, }$Ni^{2+}$, $Ca^{2+}$, $Co^{2+}$ ions. The enzyme hydrolyzed the ${\alpha}$-1,6-linkages of amylopectin, glycogens, ${\alpha}$, ${\beta}$-limited dextrin, and pullulan. The enzyme caused the complete hydrolysis of pullulan to maltotriose and the activity was inhibited by $\alpha$, $\beta$, or $\gamma$-cyclodextrins. The $NH_{2}$-terminal amino acid sequence [(Ala-Pro-Gln-(Asp of Tyr)-Asn-Leu-Leu-Xaa-ILe-Gly-Ala(Ser)] was compared with known sequences of various sources and that was compared with known sequences of various sources and that was different from those of bacterial and plant enzymes, suggesting that the enzymes are structurally different.