• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.3
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• pp.37-45
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• 2002

The vortex flow and aerodynamic load characteristics of a $65^{\circ}$ sweep delta wing with the leading edge extension in sideslip condition is investigated experimentally. The freestream velocity is 40 m/sec, which corresponds to a Reynolds number per meter of $1.76{\times}10^6$ based on the wing root chord. The angles of attack range from $12^{\circ}$ to $28^{\circ}$, and the sideslip angles treated are $0^{\circ}$ , $-10^{\circ}$, $-20^{\circ}$. The LEX vortex of the leeward side. The LEX and wing vortics coalesce to to become a concentrated strong vortex or to break down at down at downstream position. Due to the interation of the LEX and wing vortices, a high suction pressure is maintained on the windward wing surface, and a low suction pressure is formed on the leeward wing surface

• YAKHAK HOEJI
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• v.54 no.4
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• pp.252-257
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• 2010

The aim of this study was to investigate the effect of resveratrol on the pharmacokinetics of nifedipine in rats. The pharmacokinetic parameters of nifedipine were measured after the oral administration of nifenipine (6 mg/kg) in the presence or absence of resveratrol (0.5, 2.5 and 10 mg/kg, respectively). The effect of resveratrol on the P-glycoprotein (Pgp), CYP 3A4 activity was also evaluated. Resveratrol inhibited CYP3A4 enzyme activity in a concentration-dependent manner with 50% inhibition concentration ($IC_{50}$) of 0.94 ${\mu}M$. In addition, resveratrol significantly enhanced the cellular accumulation of rhodamine 123 in MCF-7/ADR cells overexpressing P-gp. Compared to the control groups, the presence of 2.5 mg/kg and 10 mg/kg of resveratrol significantly (p<0.05, p<0.01) increased the area under the plasma concentrationtime curve (AUC) of nifedipine by 49~75%, and the peak concentration ($C_{max}$) of nifedipine by 48~66%. The absolute bioavailability (AB%) of nifedipine was significantly (p<0.05) increased by 22.9-34.8% compared to the control (19.8%). The terminal half-life ($T_{1/2}$) of nifedipine was significantly (p<0.05) increased compared to the control. While there was no significant change in the time to reach the peak plasma concentration ($T_{max}$) of nifedipine in the presence of resveratrol. It might be suggested that resveratrol altered disposition of nifedipine by inhibition of both the CYP3A and P-glycoprotein efflux pump in the small intestine of rats. In conclusion, the presence of resveratrol significantly enhanced the oral bioavailability of nifedipine, suggesting that concurrent use of resveratrol or resveratrol-containing dietary supplenment with nifedipine should require close monitoring for potential drug interation.

• Journal of Ginseng Research
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• v.17 no.2
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• pp.114-122
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• 1993

0.5 mg of natural ginsenoside mixture and 0.8 $\mu$Ci of synthesized 14C-ginsenosides were administered orally to a rat and killed at one hour after the ginsenoside administration and the liver was fractionated into nuclear fraction, mitrochondria microsomes and cytosol fraction. Radioactivity distribu lion in subcellular fractions of the liver showed that 32o1c of total radioactivity absorbed in the liver was in cytosol fraction but a significant portion of the radioactivity was also found in mitochondria (26.6%) and microsomal fraction (18.l%). 5.8% of the total radioactivity was recovered from the nuclear fraction as well. This suggested that ginsenosides might be distributed into all subcellular fractions. Activities of mitochondrial aldehyde dehydrogenase, lactate dehydrogenase and malate dehydrogenase of the liver of rat at two hours after the ginsenoside administraion were found appreciably stimulated, suggesting that the ginsenoside concentration in the liver might be around 10-5%, since optimum concentrations for most enzyme catalyzed reactions in vitro were known to be 10-6% 10-4%. A significant portion of the radioactivity recovered from subcellular fractions of the liver was found in protein fractions, suggesting that proteins might interact with ginsenosides. Examination of protein-ginsenoside interation by gel filtration, equilibrium dialysis and amonium sulfate precipitation technique suggesting that proteins and ginsenosides do not bound covalently but weakl\ulcorner combined. When purified ginsenoside Rbl and Rgl were incubated with rat liver cytosolic enzymes for 20 min, the above ginsenosides were hydrolyzed quickly, suggesting that ginsenosides might be rapidly hydrolyzed and metabolized in the liver. It was also observed in vitro that the ginsenosides such as Rbl and Rgl were easily hydrolyzed by rat liver cytosol preparation suggesting that absorbed ginsenosides might be quickly hydrolyzed and metabolized in the liver.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.2
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• pp.181-186
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• 2009

In our previous report, we demonstrated that the tyrosine phosphorylation of sperm proteins (TPSP) of guinea pig was associated with capacitation and hyperactivation (CAHA), and $Ca^{2+}$ and ${HCO_3}^-$ were required for the initiation of CAHA and increasing the TPSP. The aim of this study was to further investigate the mechanism underlying the above events. The results showed that addition of cAMP agonists, dibutyryl-cAMP (db-cAMP) and isobutyl-methylxantine (IBMX), to ${HCO_3}^-$ -free medium significantly increased CAHA to the normal level (when sperm were incubated in TALP). Although addition of the cAMP agonists to $Ca^{2+}$-free medium increased CAHA, the percentages of hyperactivated and capacitated sperm were still significantly lower than the normal level. Compared with ${HCO_3}^-$ -free or $Ca^{2+}$-free medium, TPSP was increased when db-cAMP and IBMX were added in the media. H-89, a specific inhibitor of protein kinase A (PKA), inhibited CAHA in a dose-dependent manner and totally blocked TPSP. These results confirm a previous observation that $Ca^{2+}$ and ${HCO_3}^-$ regulated CAHA and TPSP in a cAMP/PKA pathway, and support an interation between TPSP and CAHA of sperm. Besides the cAMP/PKA pathway, $Ca^{2+}$ might have also played a role in regulating CAHA by other pathways since the normal level of CAHA did not recover by adding cAMP agonists in the media.

• Journal of Korean Society of societal Security
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• v.3 no.1
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• pp.33-42
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• 2010

This study predicts the stress history for truss bridge with local damages by using global-local model combination method. For this end, the global structure is modeled by 3D frame elements and the selected local details are modeled by shell elements. Then superposition principle enable the global-local model to be combined interactively. Because the frame model cannot consider the rigidity of gusset plate and the interation of structural members due to the complexity of stress distribution in truss connection. The section modification factors are proposed to calibrate the stiffness of global frame element. The global-local model combination is verified by comparing the numerical results with experimental data obtained from the proof loading test to the operating truss bridge. Furthermore, stress histrories of the truss bridge are generated in the consideration of the rigidity of truss connection with local damage by using the combination method.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.25-34
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• 2002

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia and joint destruction. The synovial fibroblasts express cell adhesion molecules and have a role in adhesive interation with inflammatory cells in synovial tissue. It has been suggested that hypoxic conditioins are thought to exist in arthritic joints, and several studies indicate that reactive oxygen species (ROS) produced in hypoxic condition can initiate events that lead to pro-adhesive changes via increased expression of adhesion molecules. So, this study wsa designed to examine whether antioxidant can inhibit hypoxia-induced expression of ICAM-1 in cultured human synovial fibroblasts. Methods: Synovial fibroblasts were isolated from synovial tissue in patients with RA and cultured at hypoxic condition. Antioxidant, PDTC (pyrrolidine dithiocarbamate) were pre-treated for an hour before the hypoxic culture and synovial fibroblasts were harvested at 0, 6, 12, 24, 48 hours time points. Cell surface ICAM-1 expression in synovial fibroblasts was examined by the flow cytometric analysis. To analyse the expression of ICAM-1 mRNA, reverse-transcriptase polymerase chain reaction (RT-PCR) was performed. The levels of cytokines in culture supernatants were measured by ELISA, and activation of NF-${\kappa}B$ was analysed by electrophoretic mobility shift assay. The adhesive reaction between synovial fibroblasts and lymphocytes was assayed by measurement of fluorescent intensity of BCECF-AM in lymphocytes. Results: Hypoxic stimuli up-regulated the ICAM-1 expression as well as the adhesive interaction of human synvial fibroblasts to lymphocytes in a time-dependent manner, and PDTC inhibited hpyoxia-induced ICAM-1 expression and cell-cell interaction. PDTC also inhibited the hypoxia-induced activation of intracellular transcription factor, NF-${\kappa}B$. PDTC decreased the amount of hypoxia-induced production of IL-$1{\beta}$ and TNF-${\alpha}$. Conclusion: These studies demonstrate that PDTC inhibit the hypoxia-induced expression of the adhesion molecule, ICAM-1 and activation of NF-${\kappa}B$ in cultured human synovial fibroblasts.

• Korean Journal of Clinical Pharmacy
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• v.20 no.1
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• pp.25-29
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• 2010

The purpose of this study was to investigate the effect of atorvastatin on the pharmacokinetics of nifedipine (6 mg/kg) after oral administration of nifedipine with or without atorvastatin (0.5 and 2.0 mg/kg) in rats, and also was to evaluate to the effect of atorvastatin on the CYP3A4 activity. The 50% inhibiting concentration ($IC_{50}$) values of atorvastatin on CYP3A4 activity is 46.1 ${\mu}M$. Atorvastatin inhibited CYP3A4 enzyme activity in a concentration-dependent manner. Coadministration of atorvastatin increased significantly (p<0.05, 2.0 mg/kg) the plasma concentration-time curve (AUC) and the peak concentration ($C_{max}$) of nifedipine compared to the control group. The relative bioavailability (RB%) of nifedipine was increased from 1.15- to 1.37-fold. Coadministration of atorvastatin did not significantly change the terminal half-life ($T_{1/2}$) and the time to reach the peak concentration ($T_{max}$) of nifedipine. Based on these results, we can make a conclusion that the significant changes of these pharmacokinetic parameters might be due to atorvastatin, which possesses the potency to inhibit the metabolizing enzyme (CYP3A4) in the liver and intestinal mucosa, and also inhibit the P-glycoprotein (P-gp) efflux pump in the intestinal mucosa. It might be suggested that atorvastatin altered disposition of nifedipine by inhibition of both the first-pass metabolism and P-glycoprotein efflux pump in the small intestine of rats. In conclusion, the presence of atorvastatin significantly enhanced the oral bioavailability of nifedipine, suggesting that concurrent use of atorvastatin with nifedipine should require close monitoring for potential drug interation.

• Journal of Korean Elementary Science Education
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• v.39 no.1
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• pp.54-68
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• 2020

The purpose of this study is to investigate how elementary teachers perceive and practice using Visual Thinking (VT) in science classes. For this, we collected 161 VT teaching materials for science that uploaded on the elementary teacher's online communities, and analyzed the characteristics. Also we interviewed four elementary teachers who have used VT in science class. The results are as follows. First, VT teaching materials shared in teacher's online communities were most often used to review the science concepts that students learned. Most of the materials required 'remember' among the Cognitive Process, and most of them provided layouts for VT activities. Second, the participants were using VT materials to review the science concepts they learned, so that students remember them. Third, the participants were satisfied because of the beliefs of effects as follows: facilitating learning and reviewing what students had learned; increasing students' positive reactions and confidence; learning through the interation among learners; the formation of habits thinking visually; indirect experiences of science class; possibility of class corresponding to learner characteristics. Fourth, the participants had difficulties in preparing for the VT science class, such as the burden of making VT materials, the long preparation time, concerns over overlapping contents, consideration of learners' VT skills, and the themselves' drawing ability. Furthermore, they also had difficulties in proceeding for the class, like different preference among learners about Visualization and loss of objectives in science class using VT. Fifth, the participants needed support as follows: platform to share students' VT results; VT case books and teachers' guidebooks; physical environment.

• Journal of Korean Medicine Rehabilitation
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• v.28 no.2
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• pp.21-35
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• 2018

Objectives The objective of this study is to determine the antimicrobial effect of Daehwanggyeonu-san(Dahwangqianniu-san,DGE) and synergistic effects with antibiotics oxacillin, ampicillin, and gentamicin against Methicillin-Resistant Staphylococcus aureus(MRSA). Methods The antibacterial activity of DGE extract was evaluated againest MRSA strains by using the Disc diffusion method, broth microdilution method(minimal inhibitory concentration; MIC), checkerboard dilution test. The checkerboard dilution test was used to examined synergetic effect of oxacillin, ampicillin, gentamicin, ciprofloxacin with DGE extract. Results DGE showed antimicrobial activity against MRSA with an MIC value of $125{\sim}250{\mu}g/mL$. In the checkerboard test, the interation of DGE with all tested antibiotics produced almost synergy or partial synergy against MRSA. Conclusions This study shows that DGE reduced the MICs of several antibiotics tested, and a remarkable antibacterial effect of DGE, with membrane permeability enhancers and ATP synthase inhibitors. This study can be a valuable source for the development of a new drug with low MRSA resistance.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.786-792
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• 2012

A microarray is a collection of thousands of DNAs or RNAs arranged on a substrate, and it enables one to navigate large amounts of gene expression. However, a researcher uses his designed experimental methods to focus on particular phenotypes from the available mass of data. In this paper, we used MicroRNAs(miRNAs) and Protein-Protein Interation(PPI) databases to enhance and expand meanings in microarray data. Further, the expanded data are linked with the Online Mendelian Inheritance in Man(OMIM), and International Statistical Classification of Diseases and Related Health Problems, $10^{th}$ Revision(ICD-10), in order to extract common genetic relationships between diseases. This approach, we expect, should provide new biological views.