• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.417-423
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• 2005

In order to investigate effects of dyeing conditions on the dyeing characteristics in silk during natural dyeing using indigo plants , various dyeing conditions including the temperature of dyeing solution, dyeing period, the concentration and pH of dyeing solution and mordants were treated. As the temperature of dyeing solution decreases low, the color of silk surface showed lower b value. The color of silk surface showed G line when the dyeing solution was $-5^{\circ}C$ and room temperature and GY line at more than $40^{\circ}C$. Coloring degree increased high as the temperature increases. Dyeing period showed no effect on the surface color, but as dyeing period was longer the coloring degree increased. When the concentration of dyeing solution was $1\~4\%$, the silk was colored to BG line and $5\%$ to B line. The coloring degree increased as the concentration of dyeing solution more increased. The pH of dyeing solution sensitively affected coloring of silk. The pH lower than 7 showed G line, pH 8 showed GY line and pH 9 showed YR line. Coloring degree decreased as pH was more increases. Surface color of silk was different according to the kinds of natural mordants and coloring degree was increased by the natural mordants.

• Corrosion Science and Technology
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• v.4 no.6
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• pp.231-235
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• 2005

The inhibitive effect of extracts of tamarind seeds and jackfruit seeds, curry leaves and henna leaves on corrosion of mild steel in 1M HCl solution have been studied by weight loss, potentiodynamic polarization and impedance measurements. Results obtained from the electrochemical techniques were in good agreement with weight loss results. From the weight loss data, the values of surface coverage ($\Theta$) and corrosion rate were calculated. The inhibition efficiency (IE) increased with increasing inhibitor concentration in 1M HCl solution. In all the cases the adsorption of the natural product extracts on the mild steel surface from 1M HCl follows the Langmuir adsorption isotherm relationship. Potentiodynamic polarization studies reveal the fact that all the four natural product extracts act as mixed type inhibitors. The decrease in the inhibition efficiency follows the order: Extracts of jackfruit seed>henna leaves>curry leaves>tamarind seed.

• Korean Membrane Journal
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• v.5 no.1
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• pp.61-67
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• 2003

Various characteristics of ion transport properties of a charged mosaic membrane with a parallel array of positive and negative functional charges were investigated, From the analysis of the volume flux, it was found that the salt flux based on nonequilibrium thermodynamics, preferential salt transport across the charged mosaic membrane. Transport properties of the magnesium sulfate(MgSO$_4$) and sucrose across the charged mosaic membrane were estimated. As a result, metal salts transport depended largely on the charged states and molecular weight otherwise nonelectrolyte solution was rejected under all experimental conditions. On the other hand, the reflection coefficient s indicated the negative value that suggested preferential material transport and was independent of charged mosaic thickness.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.811-813
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• 2008

To see the effect of magnesium on adhesion to natural zeolites, a series of batch tests were performed in this research. Mixed bacteria were sampled from the digestion tank at a local sewage treatment plant in Seoul. Magnesium-zeolites were synthesized by mixing natural zeolites with 0.096 M, 0.24 M, and 0.48 M of MgCl2 solution. For comparison, manganese and trivalent ferric zeolites were also prepared. Two grams of 0.2 mm $\sim$ 0.3 mm sized zeolites(non-treated, Mg, Mn and Fe(III) treated zeolites) and 20 mL of water were mixed in a Corex 25 mL tube. Five milliliters of culture solution including bacteria was added to the tube. The tubes were equilibrated in a shaking incubator at mesophilic temperature $(30{\pm}2^{\circ}C)$. The bacterial concentrations were measured with a Microluminometer (New Horizons 3550i) and total organic carbon (TOC) spectrophotometer (Multi NC-3100).

• Steel and Composite Structures
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• v.24 no.6
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• pp.697-709
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• 2017

The current study addresses the local buckling analysis of an infinite thin rectangular symmetrically laminated composite plate restrained by a tensionless Winkler foundation and subjected to uniform in-plane shear loading. An analytic method (i.e., one-dimensional mathematical method) is used to achieve the analytical solution estimate of the contact buckling coefficient. In addition, to study the effect of ply angle and foundation stiffness on the critical buckling coefficients for the laminated composite plates, the parametric studies are implemented. Moreover, the convergence for finite element (FE) mesh is analysed, and then the examples in the parametric study are validated by the FE analysis. The results show that the FE analysis has a good agreement with the analytical solutions. Finally, an example with the analytical solution and FE analysis is presented to demonstrate the availability and feasibility of the presented analytical method.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.341.2-341.2
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• 2002

An efficient process for the solution-phase synthesis of biaryl amides has been developed. Girard's reagent T. an inexpensive scanvenger. was found to be very efficient in trapping excess aromatic acid chlorides. resulting in water soluble by-products. which were easily removed from the products by liquid-liquid extraction. The ease of use. and the excellent purity of the amide libraries obtained are important features of this protocol. (omitted)

• Journal of Electrochemical Science and Technology
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• v.13 no.3
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• pp.347-353
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• 2022

Agarose hydrogel, a solid electrolyte, was investigated voltammetrically in terms of transport properties and natural convection effects using a ferrocenyl compound as a redox probe. To confirm the diffusion properties of solute on the agarose interface, the diffusion coefficients (D) of ferrocenemethanol in agarose hydrogel were determined by cyclic voltammetry (CV) according to the concentration of agarose hydrogel. While the value of D on the agarose interface is smaller than that in the bulk solution, the square root of the scan rate-dependent peak current reveals that the mass transport behavior of the solute on the agarose surface shows negligible convection or migration effects. In order to confirm the reduced natural convection on the gel interface, scan rate-dependent CV was performed in the solution phase and on the agarose surface, respectively. Slow scan voltammetry at the gel interface can determine a conventional and reproducible diffusion-controlled current down to a scan rate of 0.3 mV/s without any complicated equipment.

• Proceedings of the PSK Conference
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• 2003.10a
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• pp.88-88
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• 2003

The syntheses of different types of stilbenoid libraries have been studied recently. In these courses, the screening of the generated natural product-mimic focused libraries led to the identification of the novel lead compounds for human cytochrome P450 (CYP) lAs, melanin production, and sortase A. A library of trans-stilbene derivatives was prepared through a new efficient solution pahse synthetic pathway and their inhibitory activities were evaluated on human cytochrome P450s(CYP) 1A1, 1A2, and 1B1 to find a potent and selective CYP1 inhibitor. (omitted)

• Plant Journal
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• v.10 no.1
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• pp.34-39
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• 2014

Simulation works for comparing removal capabilities of acid gases contained in natural gas among several aqueous amine absorbents using commercial process simulator PROMAX(BR&E Co.) were carried out. Amine aqueous solution used in this study were 30 wt% MEA, 30 wt% DEA, 50 wt% MDEA, and 50 wt% MDEA with 3 wt% piperazine as additive. We obtained the simulated results that while MEA aqueous solution is relatively capable of more $CO_2$ gas, but DEA, MDEA, MDEA aqueous solutions with piperazine as additive are capable of more $H_2S$ gas. Also, we found that 30 wt% MDA aqueous solution is the smallest circulate rate of lean amine solution, and 50 wt% MDEA aqueous solution with 3 wt% piperazine as additive is the smallest heat duty in stripping unit. 50 wt% MDEA aqueous solution with 3 wt% piperazine as additive is found less amine circulation rate than 50 wt% MDEA due to the introduction of additive.

• Wind and Structures
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• v.25 no.5
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• pp.459-474
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• 2017

In this study an analytical expression is derived for the natural frequency of the wind turbine towers supported on flexible foundation. The derivation is based on a Euler-Bernoulli beam model where the foundation is represented by a stiffness matrix. Previously the natural frequency of such a model is obtained from numerical or empirical method. The new expression is based on pure physical parameters and thus can be used for a quick assessment of the natural frequencies of both the real turbines and the small-scale models. Furthermore, a relationship between the diagonal and non-diagonal element in the stiffness matrix is introduced, so that the foundation stiffness can be obtained from either the p-y analysis or the loading test. The results of the proposed expression are compared with the measured frequencies of six real or model turbines reported in the literature. The comparison shows that the proposed analytical expression predicts the natural frequency with reasonable accuracy. For two of the model turbines, some errors were observed which might be attributed to the difference between the dynamic and static modulus of saturated soils. The proposed analytical solution is quite simple to use, and it is shown to be more reasonable than the analytical and the empirical formulas available in the literature.