• Journal of the Korea Institute of Building Construction
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• v.14 no.2
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• pp.170-176
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• 2014

This study examined the effect of chemical attack on the stress-strain relationship of alkali-activated Hwangtoh concrete. Water-to-binder ratio and air content were selected as mixture parameters. The stress-strain relationship of concrete was measured at chemical immersion times of 0, 7, 28, 56, and 91 days from an age of 28 days. Based on the test results, the reduction in compressive strength of alkali-activated hwangtoh concrete owing to chemical attack was formulated. In sddition the present study demonstrated that the stress-strain behavior of concrete under chemical attack is significantly dependent on the air content and chemical immersion time, indicating the rate of decrease of modulus of elasticity was greater than that of compressive strength at the same immersion time. As a result, the stress-strain behavior of concrete under chemical attack was significantly inconsistent with the conventional models specified in the CEB-FIP provision.

• Progress in Superconductivity
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• v.14 no.1
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• pp.39-44
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• 2012

The fabrications condition and superconducting properties of top-seeded melt growth (TSMG) processed $GdBa_2Cu_3O_{7-y}$ (Gd123) bulk superconductors were studied. Processing parameters (a maximum temperature ($T_{max}$), a temperature for crystal growth ($T_G$) and a cooling rate ($R_G$) through a peritectic temperature ($T_P$) for the fabrication of single grain Gd123 superconductors were optimized. The magnetic levitation forces, trapped magnetic fields, superconducting transition temperature ($T_c$) and critical current density ($J_c$) of the Gd123 bulks superconductors were estimated. Single grain Gd123 bulk superconductors were successfully fabricated at the optimized processing condition. The $T_c$ of a TSMG processed Gd123 sample was 92.5 K and the $J_c$ at 77 K and 0 T was approximately $50kA/cm^2$. The trapped magnetic field contour and magnetic levitation forces were dependent on the top surface morphology of TSMG processed Gd123 samples. The single grain Gd123 samples, field-cooled at 77 K using a Nd-B-Fe permanent magnet with 5.27 kG and 30 mm dia., showed the trapped magnetic field contour of a single grain with a maximum of 4 kG at the sample center. The maximum magnetic levitation forces of the single grain Gd123 sample, field-cooled or zero field-cooled, were 40 N and 107 N, respectively.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.289-296
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• 2020

Type VI secretion system (T6SS) is a contact-dependent secretion system, employed by most gram-negative bacteria for translocating effector proteins to target cells. The present study was conducted to investigate T6SS in Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial blight in rice, and to unveil its functions. Two T6SS clusters were found in the genome of Xoo PXO99^A. The deletion mutants, Δhcp1, Δhcp2, and Δhcp12, targeting the hcp gene in each cluster, and a double-deletion mutant targeting both genes were constructed and tested for growth rate, pathogenicity to rice, and inter-bacterial competition ability. The results indicated that hcp in T6SS-2, but not T6SS-1, was involved in bacterial virulence to rice plants. However, neither T6SS-1 nor T6SS-2 had any effect on the ability to compete with Escherichia coli or other bacterial cells. In conclusion, T6SS gene clusters in Xoo have been characterized, and its role in virulence to rice was confirmed.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.51-62
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• 2010

The high concentration of N in the wastewater from livestock farming generally renders the efficiency of the wastewater treatment. Therefore, removal of N in livestock wastewater is crucial for successful treatment. The current study was conducted to investigate the optimum conditions for partial nitrification under anaerobic condition following nitritation in TPAD-BNR(two-phase anaerobic digestion-biological nitrogen removal) operating system. Sequential operating test to stimulate partial nitrification in reactor showed that partial nitrification occurred at a ratio of 1.24 in $NO_2{^-}$-N:$NH_4{^+}$-N. With this result, a wide range of factors affecting stable nitritation were examined through regression analysis. In the livestock wastewater treatment procedure, the hydraulic retention time (HRT) and pH range for optimum nitrite accumulation in the reactor were 1-1.5 days and 7-8, respectively. It was appeared that accumulation of $NO_2{^-}$-N in the reactor is due to inhibition of the $NO_2{^-}$-N oxidizer by free ammonia (FA) while the effect of free nitrous acid was minimal. Nitrification was not influenced by DO concentration at a range of 2.0-3.0 mg/L and the difference in the growth rate between $NH_4{^+}$-N oxidizer and $NO_2{^-}$-N oxidizer was dependent on the temperature in the reactor.

• Journal of Korean Society of Transportation
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• v.33 no.6
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• pp.520-530
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• 2015

This paper formulates the methodologies to estimate optimal congestion tolls from long-run and short-run perspectives and applies them to the highways of Seoul. An optimal long-run congestion toll is estimated with an optimal volume-capacity-ratio to minimize the total costs which consist of two components: road construction and maintenance costs and traveler costs. By contrast, an optimal short-run congestion toll is estimated with a supply-demand equilibrium which is determined by using a speed-flow function and a disaggregate modal choice model. The results of a long-run analysis for the Seobu urban expressway suggest the optimal volume-capacity-ratio of 1.35 and the optimal congestion toll of 503 Won per automobile kilometer. By contrast, those of a short-run analysis for the Mia-ro urban arterial suggest 1.31 and 420 Won, respectively. Although our results are to some degree dependent on the interest rate and time value assumed, one basic conclusion holds up: the congestions toll tested could generate substantial gains in social welfare if applied to Seoul.

• Korean Journal of Medicinal Crop Science
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• v.25 no.6
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• pp.404-410
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• 2017

Background: Hair loss related syndromes are increasing due to environmental pollution and stress. Hair care products are mainly prepared by mixing chemicals and natural extracts, such as those obtained from medicinal plants. The purpose of this study was to investigate the effects of 70% ethanol extracts from the flowers of Calendula officinalis, fruit body of Phellinus linteus, and the whole plant of Houttuynia cordata on the growth of CCD-986 cells, hair follicle dermal papilla cells (HFDPC), and 3T3-L1 cells. Methods and Results: All sample extracts at all concentrations, except for that from P. linteus fruit body at $500{\mu}g/m{\ell}$, were cytotoxic to CCD-986 cells. However, none of the sample extracts were cytotoxic to HFDPC. The lipid differentiation of 3T3-L1 cells regulates hair regeneration via secretion of platelet derived growth factor. The 70% ethanol extract of H. cordata whole plant promoted hair growth. Adipogenesis rate significantly increased in a treatment concentration-dependent manner. Conclusions: These results suggest that 70% ethanol extracts of C. officinalis flower, P. linteus fruit body and H. cordata could be used for the development of hair care products.

• Journal of Oriental Neuropsychiatry
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• v.16 no.1
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• pp.171-183
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• 2005

Objective : The Korean famous medicinal prescription of Subi-jeon was investigated for their antidepressant effects by tail suspension test, hot plate test, reserpine-induced hypothermia test. In addition, the monoamine oxidase activity was determined in vivo. Methods : The methanol extract reduced dose-dependently the duration of immobility in the tail suspension test, by 31.4 and 34%(p<0.05) at doses of 500mg/kg and 1g/kg, respectively, compared with control group. In comparison with this, the effect of the water extract was very weak. Results : 1. In the hot plate test, the methanol extract potently increased the jump latency time(p<0.05) compared to the control group, exhibiting the inhibition rate of 197% and 256% at doses of 500mg/kg and 1g/kg(per os), respectively, which is more effective than the water extract. 2. Both extracts suppressed the fall of body temperature induced by reserpine(reserpine-induced hypothermia) in a dose-dependent manner, showing the less effect at lower doses and better effect at higher doses compared to the water extract. 3. Both extracts inhibited the brain monoamine oxidase activity in an in vivo assay compared to the control group, the activity of water extract was better than that of the methanol extract. Conclusion : The prescription of Subi-jeon can be useful for the prevention and treatment of depression.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.3
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• pp.273-280
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• 2015

In this study, we used the mixture made from the Rice bran 45 ㎏, Dendropanax 5 ㎏, the sugar of the 10% of the total weight, and the enzyme of the 0.1% of the total weight. After the mixture were fermented for 90 days under 20 $^{\circ}C$, we measured the cell viability and the inhibition rate of the melanin biosynthesis, the activity of tyrosinase and superoxide dismutase (SOD) in malignant melanoma, B16F10 cells, in order to survey the whitening effect and the mechanism of the effects on the sample. As a result, the samples significantly suppressed the cell viability of B16F10 in more than 500 ${{\mu}g}$/㎖ and significantly inhibited the generation of melanin induced by ${\alpha}$-MSH in more than 1,000 ${{\mu}g}$/㎖. Sample decreased the activity of tyrosinase while increased the activity of SOD in dose dependent manner. Therefore, we considered that the fermentation extract made from a Rice bran and Dendropanax will be able to produce high value-added products, if used as a commercial.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.3
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• pp.626-633
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• 2007

To access the safety and efficacy of Chungyeoldodam-tang(CDT), a traditional herbal medicine prescription, on hypertension we examined various parameters involved in the pathogenesis of hypertension. CDT seems to be safe because CDT at the concentrations lower that 250 ug/ml showed no toxic effects in cultured human fibroblast and no toxic effects on liver function. The production of reactive oxygen species (ROS) were greatly decreased in CDT treated group compared with control, and angiotensin converting enzyme activities were reduced by CDT in a dose dependent manner. There was no differences in weight of hearts between control and CDT treated group. The blood pressure and pulse rate were significantly decreased. CDT greatly reduced the levels of plasma hormones including aldosterone, dopamine, and norepinephrine, but not epinephrine, and serum electrocytes including Na$^+$ and Cl$^-$, but not K$^+$. were also decreased. The levels of uric acid, BUN and creatinine were significantly decreased compared with control. These results suggested that CDT has suppressive effects on various pathologic factors in hypertension, and CDT has potential as a safe and effective therapeutics for hypertension.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.758-762
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• 1998

In preparing void latex particles by emulsion polymerization, the weight mean particle size of which is ranged $0.3{\mu}m{\sim}1.5{\mu}m$, reaction parameters were investigated in order to elucidate their effects on the size distribution and the solid content of emulsion polymer. Experimental results showed that the weight mean particle size of hydrophillic core polymer was reduced as the concentration of sodium dodecylbenzene sulfonate (SDS) increased. The size of void polymethyl-methacrylate-polystyrene composite latex particles became larger as the concentration of styrene monomer and the sodium persulfate increased. However, the size of void latex particles was reduced as the feeding rate of acrylic acid increased. The solid content of emulsion polymer was strongly dependent on the addition of stylene monomer. By increasing the concentration of styrene monomer the solid content of emulsion polymer increased linearly.