• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.12 no.2
• /
• pp.1-15
• /
• 2004

In this study, we analyze technical requirements for a 50m unmanned airship order to assure safety in the test flight operation. The 50m class unmanned airship developed by Airship Group in Korea Aerospace Research Institute(KARI). The 50m class unmanned airship was developed as a scale-down model of 200m class stratosphere unmanned airship. This study reviews specifications and characteristics of 50m class unmanned airship and develops Airworthiness Requirements on the basis of current effective Aviation Act, Airworthiness standards, and relevant international documents. The developed requirements can be applied to the safety assessment of the 200m class stratosphere unmanned airship.

• Food Science and Preservation
• /
• v.22 no.4
• /
• pp.607-612
• /
• 2015

The aim of this research was to investigate the whitening effects of rutin and rutin metabolites including 3,4-dihydroxyphenyl acetic acid (DHPAA), 3-hydroxyphenyl acetic acid (HPAA), 3,4-dihydroxytolene (DHT) and homovanillic acid (HVA). The potent whitening effect of rutin and rutin metabolites were determined by mushroom tyrosinase inhibition assay and expressed as the half maximal inhibitory concentration ($IC_{50}$) against tyrosinase activity in vitro. The HVA showed the highest inhibitory effect ($IC_{50}=37.10{\mu}M$) of tyrosinase activity, followed by DHPAA ($IC_{50}=45.87{\mu}M$), HPAA ($IC_{50}=50.96{\mu}M$), rutin ($IC_{50}=57.98{\mu}M$), and DHT ($IC_{50}=66.09{\mu}M$), respectively. To evaluate cell cytotoxicity, MTT assay was performed with JB6 P+ mouse epidermal cells and expressed as a relative percentage of untreated control. The results showed that rutin and rutin metabolites had no cytotoxic effects on JB6 P+ cells up to $100{\mu}M$ except for DHT (up to $50{\mu}M$). These results suggests that rutin metabolites may be utilized as a potential tyrosinase inhibitors and the whitening agents for the future.

• Natural Product Sciences
• /
• v.18 no.1
• /
• pp.1-7
• /
• 2012

Among 90 Vietnamese medicinal plant extracts investigated for their antioxidant activity by DPPH assay at various concentrations from $10-100{\mu}g/mL$, 67 showed an inhibition rate over 50% at $100{\mu}g/mL$; 47 had greater than 50% inhibition at $50{\mu}g/mL$; 17 showed over 50% inhibition at $25{\mu}g/mL$. 8 extracts which exhibited strong inhibitory activity more than 50% inhibition at $10{\mu}g/mL$ were further tested for lipid peroxidation inhibition by TBA assay. They displayed activity with $IC_{50}$ values from 30.6 to $158.9{\mu}g/mL$. Until now, this is the first report on antioxidant activity of the female flower of Borassus flabellifer, and the stem of Combretum latifolium, Embelia ribes, Spatholobus parviflorus, and Tetrastigma erubescens. Fractionations of the EtOAc extract prepared from S. parviflorus led to the isolation of protocatechuic acid (1), ferulic acid (2), epicatechin (3), and gallic acid (4). These compounds showed significant DPPH inhibitory activity with $IC_{50}$ values from 6.5 to $23.6{\mu}M$.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.2
• /
• pp.101-115
• /
• 2022

This study compared the performance of LiDAR in detecting objects in rough weather with that in clear weather. An experiment that reproduced rough weather divided the fog visibility into four stages from 200 m to 50 m and controlled the rainfall by dividing it into 20 mm/h and 50 mm/h. The number of points cloud and intensity were used as the performance indicators. The difference in performance was statistically investigated by a T-Test. The result of the study indicates that the performance of LiDAR decreased in the order in situations of 20 mm/h rainfall, fog visibility less than 200 m, 50 mm/h rainfall, fog visibility less than 150 m, fog visibility less than 100 m, and fog visibility less than 50 m. The decreased performance was greater when the measurement distance was greater and when the color was black rather than white. However, in the case of white, there was no difference in performance at a measurement distance of 10 m even at 50 m fog visibility, which is considered the worst situation in this experiment. This no difference in performance was also statistically significant. These performance verification results are expected to be utilized in the manufacture of road facilities in the future that improve the visibility of sensors.

• Korean Journal of Food Science and Technology
• /
• v.44 no.5
• /
• pp.607-612
• /
• 2012

Dandelions were fermented for 120 days at $15-20^{\circ}C$ in batches containing thirty and fifty percent raw sugar (FD30 and FD50). The total phenolic concentration of FD30 and FD50 were about $78.9{\pm}2.17$ and $59.35{\pm}2.56$ mg/g, respectively, both being higher than the 2$54.{\pm}1.49$ mg/g determined for DWE (dandelion water extract). The DPPH radical scavenging activity of FD30 and FD50 showed $IC_{50}$ values of $118.7{\pm}2.03$ and $123.40{\pm}2.15{\mu}g/mL$, respectively, and FD30 displayed the highest antioxidant activity. 2 mg/mL of FD30 and FD50 showed $8.8{\pm}1.72$ and $11.8{\pm}2.87{\mu}M$ production of NO, respectively, compared with $4.9{\pm}1.20{\mu}M$ of the dandelion extract. The protease, ${\alpha}$-amylase, and lipase activity of FD50 was the highest. The fibrinolytic activity of FD30 and FD50 were $0.56{\pm}0.28$ and $1.39{\pm}0.20$ unit/mg protein, respectively, which was substantially higher than the 0.28 unit/mg protein of DWE. In conclusion, the dandelions fermented by sugar showed improved antioxidant, anti-inflammatory and enzymatic activities.

• Journal of Life Science
• /
• v.16 no.7 s.80
• /
• pp.1174-1180
• /
• 2006

The present study was sought to clarify whether the combination of mental activity with subway noise affects hematological variables. Fifty-six healthy volunteers participated in this experiment and underwent a stress task consisting of combination_of mental activity (mental arithmetic) with subway noise for 50 min and 60min of recovery after the end of the stress task. Venous blood samples were collected for measuring CBC, prothrombin time (PT), activated partial thromboplastin time (aPTT), erythrocyte sedimentation rate (ESR), fibrinogen concentration, D-dimer and high sensitive C-reactive protein (H-CRP) levels before (baseline), 50min of stress task (S-50m), and 60 min of recovery (R-60m). Total leukocyte, neutrophil and lymphocyte counts significantly increased at R-60m compared with baselines. RBC count at S-50m was higher, while monocyte counts at S-50m and R-60m were lower than those of baselines. aPTTs shortened at S-50m and R-60m, but PT reduced at R-60m as compared with baselines. D-dimer and H-CRP levels at S-50m and R-60m were significantly higher than those of baselines. These findings imply that a combination of mental activity with subway noise nay cause leukocytosis, homo-concentration, shortened PT and aPTT, decreased ESR, and raised D-dimer and H-CRP levels, suggesting possible development of inflammation and prothrombogenic reaction attributable to a subway environment.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.1
• /
• pp.14-19
• /
• 2010

This study was to investigate antioxidant effects of mistletoe extracts by extraction conditions. Electron donating ability of 50% ethanol extract had shown 92.27% at 50 mL/g, which was higher than 1.0% and 0.1% L-ascorbate solutions (p<0.05). SOD-like activities were the most effective in all samples at 50 mL/g, which were barely detectable. The total polyphenol contents of water extracts including all extracts were the highest at 50 mL/g extracts (p<0.05). The nitrite scavenging effects were different depending on pH value; they were decreased overall as pH value was increased. Especially, nitrite scavenging effects were the most effective in pH 1.2, which showed more than 80% (p<0.05). Tyrosinase-inhibitory activities ranged at fewer than 10%. These results indicate that mistletoe extracts are potential sources of natural antioxidant.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.8
• /
• pp.1729-1732
• /
• 2009

Bioactivity-guided fractionation led to the isolation of two new phenylpropanoids, 3-O-p-coumaroyl-1-(4-hydroxy- 3,5-dimethoxyphenyl)-1-propanone (1) and 3-O-p-coumaroyl-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-O-$\beta$-gulcopyranosylpropanol (2), together with three known compounds, N-p-coumaroylserotonin (3), N-feruloylserotonin (4) and p-coumaric acid (5) from the leaves of Sasa quelpaertensis Nakai. Their structures were elucidated by spectroscopic methods including 1D and 2D-NMR. Compared to arbutin (I$C_{50}$ 0.048 mM) as a control, compounds 3 and 4 exhibited stronger tyrosinase inhibition activities with an I$C_{50}$ values of 0.027 mM and 0.026 mM, respectively. Compounds 1 (I$C_{50}$ 0.055 mM) and 2 (I$C_{50}$ 0.053 mM) also showed strong activities.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.9
• /
• pp.1307-1311
• /
• 2002

Twelve dietary combinations were prepared using 70 parts of fermented wheat straw (FWS) as the sole roughage supplemented with 30 parts of either the low protein concentrate mixture (Conc.-I), high protein concentrate mixture (conc.-II), maize grains (M), solvent extracted mustard cake (DMC), deoiled rice bran (DRB), uromol bran mixture (UBM), deep stacked poultry litter (DSPL), dried poultry droppings (DPD), M-DMC mixture (50:50), M-UBM mixture (50:50), M-DPD mixture (50:50) or M-UBM-DPD mixture (50:25:25) and evaluated by in-sacco technique. The above dietary combinations were also evaluated by changing the roughage to concentrate ratio to 60:40. The digestion kinetics for DM and CP revealed that FWS:DPD had the highest, whereas, the FWS:M-DMC had the lowest rapidly soluble fraction. The potentially degradable fraction was found to be maximum in FWS:M and minimum in FWS:DPD dietary combinations. The higher degradation rate of FWS:DRB and FWS:UBM combinations was responsible for their significantly (p<0.05) higher effective degradability as compared to other combinations. The highest undegradable fraction noted in FWS:M-UBM-DPD followed by FWS:DMC was responsible for high rumen fill values. The FWS:DRB, FWS:UBM and FWS:DPD combinations had higher potential for DM intake. The dietary combination with higher concentrate level (60:40) was responsible for higher potentially degradable fraction, which was degraded at a faster rate resulting in significantly higher effective degradability as compared to the corresponding dietary combination with low concentrate level (70:30). The low undegradable fraction in the high concentrate diet was responsible for low rumen fill values, which predicted of high potential for DM intake. Out of 24 dietary combinations, FWS with either of UBM, DRB, DMC, Maize, M-DMC or DPD in 70:30 ratio supplemented with minerals and vitamin A in comparison to conventional feeding practice (roughage and concentrate mixture) could be exploited as complete feed for different categories of ruminants.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.4
• /
• pp.771-780
• /
• 2014

The antioxidative effects and component analysis of the Melaleuca quinquenervia leaf extracts were investigated. All experiments were performed with 50% ethanol extract, ethyl acetate fraction and aglycone fraction obtained from dried M. quinquenervia leaves. The DPPH (1,1-phenyl-2-picrylhydrazyl) scavenging activity ($FSC_{50}$) of ethyl acetate fraction ($10.05{\mu}g/mL$) of M. quinquenervia leaf extracts was similar to (+)-${\alpha}$-tocopherol($8.89{\mu}g/mL$) known as a typical antioxidant. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of the ethyl acetate fraction ($1.61{\mu}g/mL$) and aglycone fraction ($1.07{\mu}g/mL$) of leaf extracts of M. quinquenervia on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system using the luminol-dependent chemiluminescence assay were similar to that of L-ascorbic acid ($1.50{\mu}g/mL$). The cellular protective effect of the extracts on the rose bengal sensitized photohemolysis of human erythrocytes was increased in a concentration dependant manner ($1{\sim}50{\mu}g/mL$). Especially, the cellular protective effects of Aglycone fraction (${\tau}_{50}=158.80min$) and 50% Ethanol extract (${\tau}_{50}=50.1{\pm}0.2min$) on the $^1O_2$-induced cellular damage of human cells were exhibited the higher than (+)-${\alpha}$-tocopherol (${\tau}_{50}=38.0min$). TLC and HPLC were used to analyse active components in the ethylacetate fraction of the extracts. Results showed that avicularin and quercetrin were active components of the extracts. These findings suggest that the M. quinquenervia leaf extracts can be applied to new cosmetics products as an effective antioxidant ingradient.