• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.45-50
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• 1998

13 develop an active agent for skin whitening, we examined the inhibitory effects of 285 plant extracts on tyrosinase activity and found some plant extracts have an ability to inhibit tyrosinase activity. Of these plant extracts, ramulus mori extracts showed the highest inhibiting activity on enzyme activity. From these results, we selected ramulus mori as a new active agent for skin whitening. $IC_{50}$/ of this extracts on tyrosinase activity is 12.48$\mu\textrm{g}$/m1. Also, ramulus mori extracts showed inhibitory activity on melanin synthesis in B-16 melanoma cells. We isolated active compound from ramulus mori extracts using various column chromatography and recrystalization and identified its chemical structure using Mass spectroscopy, IR and NMR analysis. So, it is identified as Mulberrin, a maior compound of ramutus mori and turned out that it has potent ability on tyrosinase inhibition. $IC_{50}$/ of this compound for tyrosinase activity is 0.5$\mu\textrm{g}$/ml. Also, this compound showed potent inhibitory activity on melanin synthesis in B-16 melanoma cells. This extracts was turned out to be safe in many safety tests.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.71-95
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• 1995

Bacteria have been regarded as a one of major etiologic factors in root canal infections. In endodontic treatment the effective removal of pathogenic microorganisms in the root canal is the key to successful outcome. Bacterial cell wall components may play an important role in the development of pulpal and periapical disease. The purpose of this study was to evaluate the effect of sonic extracts of Streptococcus spp. on cultured L929 cells and to characterize cell wall protein profiles of Streptococcus spp. Streptococcus spp. were isolated from infected root canals and identified with Vitek Systems(Biomeriux, USA). Five streptococci, namely S. sanguis, S. mitis, S uberis, S. mutans (ATCC 10449) and S. faecalis (ATCC 19433) weere enriched in brain heart infusion broth. Cell pellets were sonicated and cell wall extracts were dialyzed and membrane filtered. Prepared cell wall proteins were applied to cultured L929 cell. The cell reaction were evaluated by monitoring DNA synthesis, cell numbers and the change of cell morphology. The total cell wall protein profiles of microorganisms were characterized by sodium dodecyl sulfate polyacrylamide-gel eledruphoresis(SDS-PAGE). DNA synthesis of L929 cells were reduced by the increasing concentration of sonic extracts. DNA synthesis was significantly suppressed in more than $50{\mu}g$/ml of sonic extract conentration in five streptococci. S. nutans (ATCC 10449) showed stronger suppression on DNA synthesis than remaining four streptococci, which had the similar effect on DNA synthesis. Analysis of DNA synthesis measured by [$^3H$]-thymidine uptake was more sensitvie method than cell counting. Sonic extracts affected the microscopic findings of L929 cells. The protein profiles indicated that all five strains shared two major proteins with molecular masses of 70.8 and 57.5 kD respectively. S. uberis and S. mutans shared common minor proteins of which molecular weights were 147.9 and 112.2 kD respectively. However some minor proteins were unique for S. mitis, S. uberis and S. faecalis.

• Biomedical Science Letters
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• v.6 no.3
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• pp.201-208
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• 2000

The vancomycin, one of the family of glycopeptide antibiotics, inhibits the synthesis of bacterial cell wall peptidoglycan and has been widely used against gram-positive bacterial infections, especially for a treatment of methicillin resistant S. aureus infection. However, clinical isolate which was intermediately resistant to vancomycin (Mu50: MIC 8 $\mu\textrm{g}$/ml) was isolated in recent years. In this study we performed vancomycin susceptibility test with the increment method and population analysis with clinical isolates S. aureus. Also we did several kinds of tests with three selected isolates (s129: MIC 7 $\mu\textrm{g}$/ml, s134: MIC 7 $\mu\textrm{g}$/ml, s135: MIC 8 $\mu\textrm{g}$/ml) to find out possible mechanism of vancomycin resistance. As a result, the prevalence of vancomycin resistant S. aureus isolates among S. aureus strains resistant to methicillin was 23.3% (25/107). The vancomycin resistances of isolated strains of S. aureus were between those of Mu5O and Mu3 strains. By PCR analysis, none of the isolates with decreased vancomycin susceptibility contained known vancomycin resistant genes such as vanA, vanB, vanC1, vanC2, and vanH. Major bands of 81 kDa, 58 kDa, 33 kDa, 28 kDa were demonstrable in whole cell lysates by SDS-PAGE from all three isolates as well as reference strains. And especially,45 kDa protein was overproduced in Mu50 strains. Among them increased production of NAD$^{+}$-linked-$_{D}$-lactate dehydrogenase (dnLDH) were detected from one clinical strain (s135) and Mu5O strain. From these data, we suggest that the mechanism of vancomycin resistance in these isolates are distinct from that in enterococci.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.317-325
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• 2011

In this paper a robust voltage controller for a single-phase UPS inverter is newly presented. The voltage controller is designed using ${\mu}$-based robust control scheme to simultaneously guarantee robust stability and robust tracking performance in the presence of load variations. Firstly the robust performance of the resulting controller is theoretically confirmed via ${\mu}$-analysis. Then simulations and experiments for the single-phase inverter system with linear and nonlinear loads demonstrate feasibility of the proposed control method providing improved performance - good regulation and fast dynamic response.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.562-568
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• 2014

In this work, synthesis, characterization and antimicrobial activity of series of imidazolines-oxazolines scaffolds 5a-f and 10a-d have been investigated. All the imidazolines-oxazolines derivatives were prepared from acid derivatives 1 and 6a-c, and enantiomerically pure (S)-2-amino-3-methyl-1-butanol in four steps with excellent optical purity. The structures of all newly synthesized compounds have been elucidated by $^1H$, $^{13}C$ NMR, GCMS, and IR spectrometry. Their purity was confirmed using elemental analysis. Some newly synthesized compounds were examined to in-vitro antimicrobial activity. Among the prepared products 10d was found to exhibits the most active against all tested bacteria and fungi with minimal inhibitory concentration (MIC) ranged between 21.9 and $42.6{\mu}g/mL$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.2
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• pp.342-348
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• 2000

In this experiment, we show the effects of herbal plant extracts on the production of nitric oxide (NO) and TNF-$\alpha$. The extracts of Angelica gigas, Astragalus membranaceus, Acanthopanax sessiliflorus and Houttuynia cordata had no effect on NO synthesis by itself in mouse macrophage cell line (RAW264.7). However, the stimulation with these extracts in the presence of murine interferon-${\gamma}$(mIFN-${\gamma}$) resulted in increased NO synthesis. When these extracts were used in combination with mIFN-${\gamma}$, there were a marked cooperative induction of NO and TNF-$\alpha$ synthesis in a dose-dependent manner. The same results were obtained in the mouse peritoneal macrophages used. The optimal concentration of these extracts on NO synthesis was shown at 100$\mu\textrm{g}$/mL with 100U/mL of mIFN-${\gamma}$. NO synthesis was inhibited by NG-monomethyl-L-arginine. When cell lines were treated with extracts, the expression of inducible NO synthetase (iNOS) was markedly increased in RT-PCR analysis. In addition, synergy between mIFN-${\gamma}$ and extracts was dependent on extracts-induced tumor necrosis factor-$\alpha$(TNF-$\alpha$). These results suggest that water extracts of herbal plants can induce iNOS, NO and TNF-$\alpha$ synthesis of mouse macrophage cell line (RAW264.7) and peritoneal macrophages in combination with mIFN-${\gamma}$.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.104-109
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• 1991

Carbamates are generally used as insecticide, thus 8-hydroxy-5-chloroquinolinyl-N-ethylcarbamate was newly synthesized. Its physical properties were determined and chemical structure was identified by means of IR, nmr in addition to elemental analysis. The effect of the compound on rat's ileum, and antibacterial activity against Staphylococcus aureus, Salmonella typhi, E. coli, and Pseudomonas aeruginosa were examined. It was observed that the dosage over 100 $\mu$g/ml of the compound relaxed rat's ileum and the same dosage of the compound inhibited growth of the above strains of bacteria.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2627-2634
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• 2012

Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel ${\beta}$-methoxyacrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, $^1H$ nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds (1a-1h) exhibited potent antifungal activities against Colletotrichum orbiculare, Botrytis cinerea Pers and Phytophthora capsici Leonian at the concentration of 50 ${\mu}g/mL$. Exhilaratingly, compound 1d (R=3-trifluoromethylphenyl) showed better antifungal activity against all the tested fungi than the commercial strobilurin fungicide azoxystrobin.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.5
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• pp.401-409
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• 2013

Numerical analysis on RF (Radio-Frequency) thermal plasma treatment of micro-sized Ni metal was carried out to understand the synthesis mechanism of nano-sized Ni powder by RF thermal plasma. For this purpose, the behaviors of Ni metal particles injected into RF plasma torch were investigated according to their diameters ($1{\sim}100{\mu}m$), RF input power (6 ~ 12 kW) and the flow rates of carrier gases (2 and 5 slpm). From the numerical results, it is predicted firstly that the velocities of carrier gases need to be minimized because the strong injection of carrier gas can cool down the central column of RF thermal plasma significantly, which is used as a main path for RF thermal plasma treatment of micro-sized Ni metal. In addition, the residence time of the injected particles in the high temperature region of RF thermal plasma is found to be also reduced in proportion to the flow rate of the carrier gas In spite of these effects of carrier gas velocities, however, calculation results show that a Ni metal particle even with the diameter of $100{\mu}m$ can be completely evaporated at relatively low power level of 10 kW during its flight of RF thermal plasma torch (< 10 ms) due to the relatively low melting point and high thermal conductivity. Based on these observations, nano-sized Ni metal powders are expected to be produced efficiently by a simple treatment of micro-sized Ni metal using RF thermal plasmas.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.1
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• pp.1-7
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• 2001

For a parametric uncertain system, there are many results on stability analysis, but only a few synthesis methods. In this paper, we proposed a new target polynomial decision method for the parametric uncertain system to stabilize the closed loop system with maximal parametric $l_2$ stability margin. To this, we used both Lipatov Theorem and coefficient diagram method(CDM). To show the effectiveness of the proposed method, we designed a robust controller for the inverted pendulum system with parametric uncertainties using fixed order pole assignment(FOPA) method and its performance was compared with that of the ${\mu}$ synthesis methods.