• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.82-85
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• 2008

Hyungbangjihwang-Tang (HT), an Oriental herbal formula, has been known to play a role which helps to recover vigor of human in the Orient. In this study, antibacterial substance (HTI) was purified from the ethyl-acetate extracts of HT by using $SiO_2$ column chromatography and HPLC, and the antibacterial effects of HTI were investigated. By using the CLSI broth micro-dilution assay, the activity of HTI was evaluated against human pathogenic Gram-positive and Gram-negative bacterial strains including the clinical isolates of methicillin-resistant Staphylococcus aureus. The results demonstrated that HTI showed broad spectrum antibacterial activities against all bacterial strains tested. In conclusion, HTI is an interesting new molecule for its potential in anti-infective drug discovery and for future studies on activity-structure relationship through analysis of its chemical structure.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.273-279
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• 2009

Hyungbangjihwang-Tang (HT), an Oriental herbal formula, has been known to play a role which helps to recover vigor of human in the Orient. In this study, antifungal substance (HTI) was purified from the ethyl-acetate extracts of HT by using $SiO_2$ column chromatography and HPLC, and the antifungal effects of HTI and its mode of action were investigated. By using a broth micro-dilution assay, the activity of HTI was evaluated against fungi. HTI showed antifungal activities without hemolytic effect against human erythrocytes. To confirm antifungal activity of HTI, we examined the accumulation of intracellular trehalose as stress response on toxic agents and effect on dimorphic transition in Candida albicans. The results demonstrated that HTI induced the accumulation of intracellular trehalose and exerted its antifungal effect by disrupting the mycelial forms. To understand its antifungal mode of action, cell cycle analysis was performed with C. albicans, and the results showed HTI arrested the cell cycle at the S phase in yeast. The present study indicates that HTI has considerable antifungal activity, deserving further investigation for clinical applications.

• Mass Spectrometry Letters
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• v.3 no.4
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• pp.93-100
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• 2012

Cellular processes such as proliferation, differentiation, and adaptation to environmental changes are regulated by protein phosphorylation. In order to enhance the understanding of molecular dynamics for biological process in detail, it is necessary to develop sensitive and comprehensive analytical methods for the determination of protein phosphorylation. Neural stem cells hold great promise for neural repair following an injury or disease. In this study, we made differentiated oligodendrocytes from human neural stem cells using over-expression of olig2 gene. We confirmed using quantitative phosphoproteome analysis approach that combines stable isotope labeling by amino acids in cell culture (SILAC) and $TiO_2$ micro-column for phosphopeptide enrichment with $MS^2$ and $MS^3$ mass spectrometry. We detected 275 phosphopeptides which were modulated at least 2-fold between human neural stem cells and oligodendrocytes. Among them, 23 phosphoproteins were up-regulated in oligodendrocytes and 79 phosphoproteins were up-regulated in F3 cells.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3284-3288
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• 2013

This paper describes first development and validation of pentafluorophenylprophyl ligand-based liquid chromatography coupled to tandem mass spectrometry (PFPLC-MS/MS) method to determine metformin, a highly polar compound, in human plasma. Metformin and Phenformin (internal standard) were extracted from human plasma 50 ${\mu}L$ with a single-step protein precipitation. The chromatographic separation was performed using a linear gradient elution of mobile phase involving 5.0 mM ammonium formate solution with 0.1% formic acid (A) and acetonitrile (B) over 3.0 min of run time on a Phenomenex Luna PFP column. The detection was performed using a triple-quadrupole tandem mass spectrometer (Waters Quattro micro) with electrospray ionization in the mode of positive ionization and multiple-reaction monitoring (MRM). The developed method was validated with 5.0 ng/mL of lower limit of quantification (LLOQ). The calibration curve was linear over 5-3000 ng/mL of the concentration range ($R^2$ > 0.99). The specificity, selectivity, carry-over effect, precision, accuracy and stability of the method met the acceptance criteria. The method developed in this study had had rapidness, simplicity and ruggedness. The reliable method was successfully applied to high throughput analysis of real samples for a practical purpose of a pharmacokinetic study.

• Journal of Ginseng Research
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• v.40 no.3
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• pp.220-228
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• 2016

Background: Among the various ginseng strains, Shizhu ginseng is endemic to China, mainly distributed in Kuandian Manchu Autonomous County (Liaoning Province, China); however, not much is known about the compounds (especially saponins) in Shizhu ginseng. Methods: A rapid, sensitive, and reliable ultra-high performance liquid chromatography coupled with MS/MS (UHPLC-MS/MS) method was developed to separate and identify saponins in Shizhu ginseng. Results: The separation was carried out on a Waters ACQUITY UPLC BEH $C_{18}$ column ($100mm{\times}2.1mm$, $1.7{\mu}m$) with acetonitrile and 0.1% formic acid aqueous solution as the mobile phase under a gradient elution at $40^{\circ}C$. The detection was performed on a Micromass Quattro Micro API mass spectrometer equipped with electrospray ionization source in both positive and negative modes. Under the optimized conditions, a total of 31 saponins were identified or tentatively characterized by comparing retention time and MS data with related literatures and reference substances. Conclusion: The developed UHPLC-MS/MS method was suitable for identifying and characterizing the chemical constituents in Shizhu ginseng, which provided a helpful chemical basis for further research on Shizhu ginseng.

• Journal of the Korean Geosynthetics Society
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• v.22 no.2
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• pp.13-21
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• 2023

Mean sea level has recently been rising due to global warming causing coastal erosion. As Korea is peninsula, the land loss due to coastal erosion is critical. An approach in this study is cementing the coastal area using bacteria, which is called microbially induced carbonate precipitation (MICP). This study tried to see how fresh water and sea water work with MICP as a solvent. Ureolytic activity during the MICP reaction was measured with deionized and sea water. A soil column was prepared to evaluate the strength of MICP-treated sand. Sands were treated by MICP with surface percolation method. As the treatmen t style was different with other conventional methods, several methods were proposed to properly evaluate the MICP-treated sand surface. A micro-scale evaluation was performed to assess the mineral structure treated by different solvents. As results, sea water rendered the ureolytic reaction slower. A needle penetrometer worked well to evaluate the MICP-treated sand surface. This study confirmed the utilization of sea water is feasible as the solvent of MICP.

• Korean Journal of Food Science and Technology
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• v.14 no.2
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• pp.122-124
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• 1982

The triglyceride composition of Korean hazel nut (Corylus heterophylla Fisch. var. Japonica koidz) was determined by high performance liquid chromatography (HPLC) using a $C_{18}$ micro Bondapack column with acetonitril-chloroform-tetrahydrofuran(75 : 15 : 10, v/v/v) and acetonitril-tetrahydrofuran (70 : 30, v/v) solvent mixtures as mobile phase. The triglyceride consisted of 4.14% $C_{38}$, 5.23% $C_{40}$, 10.03% $C_{42}$, 24.02% $C_{44}$, 48.73% $C_{46}$ and 7.85% $C_{48}$ with acetonitril-chloroform-tetrahydrofuran (75 : 15 : 10, v/v/v) mobile phase and 4.51% $C_{38}$, 5.98% $C_{40}$, 11.45% $C_{42}$, 25.14% $C_{44}$ and 52.92% $C_{46}$ with acetonitril-tetrahydrofuran (70 : 30, v/v) mobile phase.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.358-368
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• 2011

Responses of plankton populations to nutrient enrichment in mesocosm experiments in Shihwa lake were simulated using FVCOM. Dissoloved oxygen module was added to the FVCOM to simulate impacts of its decreased levels. The ecological model included the major components of the pelagic ecosystem including nutrients, phytoplankton (pico-, nano-, micro-), zooplankton (two groups of protozoa, mesozooplankton), particulate organic matter, dissolved organic matter and bacteria, and was calibrated using trophodynamic data collected from Gyeonggi Bay and Shihwa Lake. The model was able to reproduce major responses of plankton populations to nutrient enrichment, including phytoplankton of different size groups, change of dominance of protozoa from < 20 ${\mu}m$ oligotrichs to scuticociliates, and reponses to bacteria and low levels of dissolved oxygen in water column of the mesocosms.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1083-1087
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• 1999

Microstructures and the gas-sensing characteristics of the $\textrm{SnO}_2$ thin films were studied, which were deposited at various conditions (rf power, sample temperature, $\textrm{O}_2$/Ar ratio) by the rf magnetron sputtering. As a result, six typical microstructures were derived, such as amorphous(A), amorphous mixed with polycrystalline grains (A+P), polycrystalline with random crystalographic orientation (P), fine columnar (FC), coarse columnar (CC) and Zone T (T) with dense fiberous structure. Typically, A, A+ P, and P structures were formed when no $\textrm{O}_2$ was added to the sputter gas, whereas FC, CC, and T structures were obtained when $\textrm{O}_2$ was added. The A structure formed at low rf power and low temperature, the A+P at high rf power and low temperature, and the P at high rf power and high temperature. The FC structure was obtained at low rf power and low temperature. the CC at low rf power and high temperature, and the T at high rf power and low temperature. Results of the gas-sensing test of the sensor chips fabricated from the typical films indicated that the fine columnar microstructure shows the highest sensitivity both at $300^{\circ}C$ and $400^{\circ}C$. It was proposed that this is due to the high specific surface area of the micro-columns.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.259-266
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• 2012

A general earthquake resistant design philosophy of ductile frame buildings allows beams to form plastic hinges adjacent to beam-column connections. In order to carry out this design philosophy, the ultimate bond or shear strength of the beam should be greater than the flexural yielding force and should not degrade before reaching its required ductility. The behavior of RC members dominated by bond or shear action reveals a dramatic reduction of energy dissipation in the hysteretic response due to the severe pinching effects. In this study, a method was proposed to predict the deformability of reinforced concrete members with short-span-to-depth-ratios, which would result in bond failure after flexural yielding. Repeated or cyclic loading produces a progressive deterioration of bond that may lead to failure at lower cyclic bond stress levels. Accumulation of bond damage is caused by the propagation of micro-cracks and progressive crushing of concrete in front of the lugs. The proposed method takes into account bond deterioration due to the degradation of concrete in the post yield range. In order to verify bond deformability of the proposed method, the predicted results were compared with the experimental results of RC members reported in the technical literature. Comparisons between the observed and calculated bond deformability of the tested RC members showed reasonably good agreement.