• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.889-893
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• 2012

전 국토의 약 7.6%를 차지하고 있는 밭은 장마철이나 집중호우에 의해 하천의 탁수문제를 유발할 뿐만 아니라, 수생태계에도 악영향을 미치기 때문에 비점오염원을 저감시켜야 한다. 이러한 비점오염원을 줄이기 위한 여러 최적관리방법 중 침사구를 밭의 유출부에 적용하여 비점오염물질의 유출저감효과를 평가 하고자 하였다. 평가 방법은 6개(각 110m2)의 무밭을 조성하여 무 재배기간(2011년 4월부터 7월) 동안 시험포에서 발생하는 강우유출수를 1.125 m3($1.5m{\times}1.5m{\times}0.5m$) 크기의 침사구 3개로 각각 유입되도록 하였다. 침사구로 유입된 유출수는 토양으로 침투 및 저류 또는 증발되도록 하였고, 강우에 의한 유출수의 양이 침사구의 용량보다 클 경우 침사구 유출부를 통해 유출되도록 하였다. 연구 결과 평균 64.1%의 유출량 저감효과가 있는 것으로 나타났으며, 수질농도는 BOD5 39.0%, SS 62.1%, CODMn 43.4%, DOC 43.5%, T-N 40.0%, T-P 41.2%의 저감효과가 있는 것으로 나타났다. 유출량과 수질농도를 고려한 오염부하 저감효과는 유출량이 적었던 #2와 #3의 침사구에서 모든 수질항목에서 각각 80%와 90% 이상의 저감효과가 나타났다. 본 연구의 결과를 바탕으로 밭에서 발생하는 비점오염물질 저감을 위해 밭의 유출부에 작은 웅덩이와 같은 침사구를 설치할 경우 비점오염을 저감하는데 매우 효과적인 것으로 판단된다. 또한 강우유출수가 적을 경우 침사구에 의한 유사량의 저감효과도 매우 클 것으로 판단된다. 따라서 밭에서 발생하는 비점오염원을 줄이기 위해서는 본 연구와 같이 밭의 지표를 볏짚이나 다른 피복재 등으로 피복하여 토양의 이동을 최소한으로 줄여 오염부하량을 저감하고, 유출이 발생할 경우 밭의 유출부에 침사구를 설치하여 하천으로 유입되는 오염물질을 저감해야 할 것으로 판단된다.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.567-571
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• 1997

Numbers of chemical agents which have been shown to inhibit either auxin signal transduction pathway or ethylene formation in plant cells were applied to cut flower stems of snapdragon (Antirrhinum majus L.) and their effects on the postharvest gravitropic response were studied. The chemical treatments were done by submerging either the stem base or the top part of cut flower, which involves the gravistimulus-sensitive region, for 1 h at $25^{\circ}C$. When the chemicals were supplied from the cut stem base, the gravitropic upward bending of flower stalks kept horizontally after the treatments with 20 mM CDTA or 10 mM $CoCl_2$ was comparable to that of the untreated control, but o-vanadate showed a certain degree of effectiveness for suppressing the bending response. In contrast, the direct application of those agents to the gravitropically sensitive region of cut flowers in the presence of 0.01% Triton X-100 resulted in a substantial reduction of the gravitropic response. In the case of 20 mM $CoCl_2$ treatment, almost total elimination of gravitropism without any significant deterioration of flower quality was observed. The results indicate the possibility of preparation of a protocol involving $CoCl_2$ and a proper surfactant for commercial use to suppress the gravitropic response of cut flowers during postharvest storage and transportation.

• Journal of Life Science
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• v.20 no.9
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• pp.1365-1372
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• 2010

We investigated the inhibitory effects of solvent extracts from dried yam on $H_2O_2$-induced oxidative stress and growth of cancer cell lines (HT1080 human fibrosarcoma and HT-29 human colon cancer cells). Yam (Dioscoreacea) has been recognized as a healthy food due to its various biological activities, such as anti-obesity, anti-constipation, anti-proliferation, and anti-mutagenic activities, as well as its ability to decrease blood glucose and cholesterol levels. In order to determine the protective effect on $H_2O_2$-induced oxidative stress, DCFH-DA (dichlorodihydrofluorescin diacetate) assay was conducted. Acetone with methylene chloride (A+M) extract of dried yam appeared to reduce the levels of intracellular reactive oxygen species (ROS) with dose responses. Among the fractions, 85% aq. methanol fraction showed the highest protective effect on production of lipid peroxides. Inhibitory effects of A+M and methanol (MeOH) extracts on the growth of HT1080 and HT-29 cancer cells increased in a dose dependent manner. The treatments of n-hexane, 85% aq. methanol and n-butanol fractions (${\geqq}0.5$ mg/ml concentrations) significantly inhibited the growth of both cancer cells (p<0.05). From these results, 85% aq. methanol fraction showed inhibitory effects on cellular oxidation and growth of human cancer cells, suggesting that this fraction may contain active compounds of dried yam.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.4
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• pp.293-300
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• 2009

In this study, we investigated the antioxidative activity and inhibitory effects on elastase and tyrosinase of Persicaria hydropiper L. extracts. The free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities ($FSC_{50}$) of ethyl acetate fractions of Persicaria hydropiper L. was $5.23\;{\mu}g/mL$. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of some Persicaria hydropiper L. extracts on ROS generated in $Fe^{3+}$-EDTA/$H_2O_2$ system were investigated using the luminol - dependent chemiluminescence assay. The ROS scavenging activities ($OSC_{50}$) of ethyl acetate fractions of Persicaria hydropiper L. was $0.40\;{\mu}g/mL$. The protective effects of extract / fractions of Persicaria hydropiper L. on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The Persicaria hydropiper L. extracts suppressed photohemolysis in a concentration dependent manner ($1\;{\sim}\;10\;{\mu}g/mL$). Inhibitory effects ($IC_{50}$) on tyrosinase of aglycone fraction of Persicaria hydropiper L. extracts was $8.90\;{\mu}g/mL$. Inhibitory effects ($IC_{50}$) on elastase of aglycone fraction of Persicaria hydropiper L. extracts was $2.37\;{\mu}g/mL$. These results indicate that extract / fractions of Persicaria hydropiper L. can function as antioxidants in biological systems, particularly skin exposed to UV radiation by anti-oxidative activity and protect cellular membranes against ROS. Persicaria hydropiper L. extract / fractions could be used as a new cosmeceutical for whitening and anti-wrinkle products.

• Food Science and Preservation
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• v.21 no.4
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• pp.549-559
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• 2014

This study investigated the hypoglycemic effects of mulberry leaf (M), green tea (G), and a mixture of mulberry leaf and green tea (MG) in rats with streptozotocin-induced diabetes. Male Sprague-Dawley rats were divided into the non-diabetic (N) and diabetic groups. The experimental animals were divided into four groups and fed the following for four weeks: a normal diet (N), the STZ+normal diet (STZ), the STZ+5% mulberry leaf (STZ-M), STZ+5% green tea (STZ-G), and the STZ+5% mixture of mulberry leaf and green tea (STZ-MG). The whole blood glucose level of the STZ-M, STZ-G and STZ-MG groups significantly decreased compared to the STZ group two weeks later. The serum glucose and fructosamine, and urine glucose levels in the STZ-M, STZ-G and STZ-MG groups were lower than in the STZ group. The levels of serum insulin were higher in the STZ-M, STZ-G and STZ-MG groups than in the STZ group. However, serum glucose, fructosamine and insulin levels, and urine glucose levels were not significantly different among the STZ-M, STZ-G and STZ-MG groups. These results indicate that mulberry leaf, green tea, and their mixture help prevent or attenuate the progression of diabetes in rats with STZ-induced diabetes.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.23-31
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• 2012

The purpose of this study is to analyze earth pressure acting on a circular shaft-tunnel considering arching effect by centrifuge modeling test on sands. The centrifuge testing method provides a way to model an in-situ stress state condition with a stress gradient within a laboratory specimen. A small-scale model of circular shaft-tunnel, which has a real diameter of 6.0 m and height of 15.0 m, was designed and tested twice under 75g-level. Additionally, an effect of excavation was presented by separating two segments of circular shaft wall to find behavioral properties and strength of earth pressure along with excavating ground. The test results were compared with those of the proposed earth pressure equation. The test results showed that earth pressure decreased by about 70% in comparison with existing two-dimensional earth pressure. This fact might be attributed to three-dimensional arching effects.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1167-1172
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• 2018

Carbon nanotubes (CNTs) are structures of carbon atoms bonded together in hexagonal honeycomb shapes, with multi-walled CNTs having a very high thermal conductivity of $3000W/m{\cdot}K$ and single-walled CNTs having a conductivity of $6000W/m{\cdot}K$. In this work, the transmittance and the thermal diffusivity of a multi-walled carbon nanotube dispersion with a concentration of 1.5 M were measured using a single beam method, a dual beam method, and the thermal lens effect. The nonlinear optical coefficients were obtained by using the z-scan method, which moved the sample in the direction of propagation of the single laser beam, propagation and the thermal diffusivity was measured using a double laser beam. As a pump beam, a diode-pumped solid state (DPSS) laser with a wavelength of 532 nm and an intensity of 100 mW was used. As the probe beam, a He-Ne laser having a wavelength of 633 nm and an intensity of 5 mW was used. The experimental result shows that when the concentrations of the sample were 9.99, 11.10, 16.65, and 19.98 mM, the nonlinear absorption coefficients were 0.046, 0.051, 0.136 and 0.169 m/W, respectively. Also, the nonlinear refractive indices were 0.20, 0.51, 1.25 and $1.32{\times}10^{-11}m^2/W$, respectively, and the average thermal diffusivity was $1.33{\times}10^{-6}m^2/s$.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.64-70
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• 2015

In order to control garlic white rot (Sclerotium cepivorum), which threatens garlic production in farmers fields, soil solarization (solar sterilization), sclerotia germination inducers and effective microorganisms as biological control agents, and chemical fungicides have been used. Among them, fungicide has been largely used to reduce garlic white rot. In this study, the antifungal activities of five fungicides, prochloraz(a.i. 25%, EC), tebuconazole (a.i. 25%, WP), flutolanil (a.i. 15%, EC), iminoctadine tris-albesilate (a.i. 40%, WP) and isoprothiolane (a.i. 40%, EC) with different mode of action, in mycelial growth, sclerotia germination and sclerotia production, were tested. The inhibitory effects of the 5 fungicides on the mycelial growth, and sclerotia germination and production of garlic white rot pathogen (S. cepivorum T11-2) were investigated on potato dextrose agar (PDA) and their control efficacies were evaluated on garlic flakes. There was no mycelial growth of S. cepivorum T11-2 on PDA amended with $0.8{\mu}g\;mL^{-1}$ of prochloraz or $100{\mu}g\;mL^{-1}$ of tebuconazole. Also prochloraz and tebuconazole inhibited perfectively the sclerotia germination of the pathogen at 10 and $1.0{\mu}g\;mL^{-1}$, respectively. In spite of a very low activity of isoprothiolane in mycelial growth and sclerotia germination of S. cepivorum T11-2, it showed a good inhibitory activity against sclerotia production of S. cepivorum T11-2 on PDA amended with $1.67{\mu}g\;mL^{-1}$. Prochloraz, tebuconazole and flutolanil showed above 70% of control value when they were treated at $100{\mu}g\;mL^{-1}$ using the garlic flake cutting-method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.10
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• pp.1469-1473
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• 2011

The efficacy of antimicrobial agents and heat treatments on spore inactivation was investigated. Grapefruit seed extract (GFE) and ethylenediaminetetraacetic acid (EDTA) were used and as antimicrobial agents, and heat treatments were conducted at $70^{\circ}C$, $80^{\circ}C$, and $90^{\circ}C$ for 30 minutes. Heat treatments at $90^{\circ}C$ were the most effective on spore inactivation as a single treatment and caused a 2.3 log reduction. When combined with a single treatment to discover synergistic effects, 1% GFE with $80^{\circ}C$ heat treatments and 0.5 mM EDTA with $80^{\circ}C$ heat treatments resulted in 2.1 log and 3.2 log reductions, respectively, though they did not show reductions at each single treatment (GFE 1% (v/v), EDTA 0.5 mM, $80^{\circ}C$). So it was concluded that by combining GFE, EDTA in low concentration treatment, and heat treatment, B. cereus spores can be effectively inactivated.

• Korean journal of applied entomology
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• v.55 no.2
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• pp.109-117
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• 2016

We investigated the control of Bemisia tabaci adults in tomato greenhouses using the eggplant as a trap plant with 4 systemic chemicals. The control effect of dinotefuran SG 50% on tobacco whitefly adults was 80% mortality, the highest than that cyantraniliprole, pyridaben and clothianidin, 51.0%, 12.4% and 11.0% respectively when all chemicals with recommended doses were used. Dinotefuran was applied at various doses and was observed to be most effective above 200ppm (88.4%)t. The control effect of dinotefuran lasted for appromimately nine 9 days and the density of tobacco whitefly adults increased there after. In field tests, the densities of tobacco whitefly adults on tomato shoots were highest at points 0, 15 and 20 m from the eggplant traps and lowest at 5 and 10 m. When the density of tobacco whitefly was low and the eggplants with dinotefuran SG 50% were placed in the tomato greenhouse at 10 m intervals, the overall density of tobacco whitefly adults was lower. In addition, densities were higher at the side of the greenhouse than in the interior and further away from the eggplant. When the density of tobacco whitefly was high and the eggplants with dinotefuran were placed at 5 m intervals, the density of tobacco whitefly at each 5 m point decreased. Theses results confirm that the eggplant is an effective trap plant for attracting tobacco whitefly audlts and combined with dinotefuran SG 50% decreases the density of tobacco whitefly in tomato greenhouses.