• Structural Engineering and Mechanics
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• v.71 no.5
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• pp.525-544
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• 2019

In the present study, buckling and free vibration analyses of annular thin sector plate made of functionally graded materials (FGMs) resting on visco-elastic Pasternak foundation, subjected to external radial, circumferential and shear in-plane loads is investigated. Material properties are assumed to vary along the thickness according to an power law with Poisson's ratio held constant. First, based on the classical plate theory (CPT), the governing equation of motion is derived using Hamilton's principle and then is solved using the generalized differential quadrature method (GDQM). Numerical results are compared to those available in the literature to validate the convergence and accuracy of the present approach. Finally, the effects of power-law exponent, ratio of radii, thickness of the plate, sector angle, and coefficients of foundation on the fundamental and higher natural frequencies of transverse vibration and critical buckling loads are considered for various boundary conditions. Also, vibration and buckling mode shapes of functionally graded (FG) sector plate have been shown in this research. One of the important obtained results from this work show that ratio of the frequency of FG annular sector plate to the corresponding values of homogeneous plate are independent from boundary conditions and frequency number.

• Journal of Plant Biotechnology
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• v.8 no.1
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• pp.21-25
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• 2006

Phragmites australis (reed) has received much attention as being one of the principle emergent aquatic plants for treating industrial and civil wastewater. Plant regeneration via plant tissue culture in p. australis was investigated. Three types of callus were identified from seeds on N6 medium plus 4.5 UM 2,4-dichlorophenoxyacetic acid (2,4-D). Yellow compact type showed the best redifferentiation, whereas white compact type and yellow friable were not competent to differentiate into plane. Solid medium culture was better than liquid suspension culture for enhancing callus growth when N6 medium supplemented with 4.5 ${\mu}M$ 2,4-D was used. Phytagel, as a gelling agent, was superior to agar in plant regeneration on N6 medium, supplemented with 9.4 ${\mu}M$ kinetin and 0.54 ${\mu}M$ $\alpha$-naphthaleneacetic acid (NAA). Transfer of the plantlets regenerated from kinetin and NAA-supplemented N6 medium to growth regulator-free MS medium enhanced the further development of the plantlets. Plantlets on subsequently grown to maturity when tansferred to potting soil. The regenerated plants exhibited morphologically normal. The system for plant regeneration of P. australis enables to propagate elite lines on a large scale for water purification in the ecosystem

• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.5-9
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• 2007

Zygotic embryos just after harvest of seeds were immature globular to heart stage. Maturation of zygotic embryos rapidly proceed when zygotic embryos together with small excised parts of endosperm were cultured on 1/3-strength MS solid medium with 2% sucrose, and the zygotic embryos were germinated within two months. Embryogenic callus was formed from the excised segments of germinating zygotic embryos of Eleutherococcus pedunclus on Murashige and Skoog (MS) medium with $4.5{\mu}M$ 2,4-D. The embryogenic callus formation occurred at a low frequency (less than 7%) from hypocotyl segments. The embryogenic calli were maintained on the same medium as primary medium. High frequency somatic embryogenesis was obtained after the cells were transferred to medium lacking 2,4-D. Cotyledonary embryos were germinated and converted into plantlets on medium with $20{\mu}M$ $GA_3$. Embryogenic callus and somatic embryos were produced spontaneously on the surfaces of roots and/or hypocotyls of plantlets. The frequency of embryogenic callus formation was 85% in roots and 34% in hypocotyls. Therefore maintain of cell lines performed very easily. Plantlets with developed epicotyls at more than 3 cm acclimatized at high frequency (89%). While plantlets with small epicotyls (less than 1 cm) were acclimatized at low rate (32%). The soil survived plantlets produced new sprouts after over wintering in the field.

• Journal of Pharmaceutical Investigation
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• v.41 no.4
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• pp.239-247
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• 2011

Simvastatin is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which catalyzes the conversion of HMG-CoA to mevalonate, an early and rate-limiting step in the biosynthesis of cholesterol. Simvastatin has good permeability, but it also has low solubility (BCS class II), which reduces its bioavailability. To overcome this problem, a solid dispersion is formed using a spray-dryer with polymeric material carrier to potentially enhance the dissolution rate and extend drug absorption. As carriers for solid dispersion, Gelucire$^{(R)}$44/14 and Gelucire$^{(R)}$ 50/13 are semisolid excipients that greatly improve the bioavailability of poorly-soluble drugs. To avoid any toxic effects of an organic solvent, we used aqueous medium to melt Tween$^{(R)}$ 80 and distilled water. The structural behaviors of the raw materials and the solid dispersion were analyzed by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The DSC and PXRD data indicated that the crystalline structure of simvastatin was transformed to an amorphous structure through solid dispersion. Then, solid dispersion-based tablets containing 20 mg simvastatin were prepared with excipients. Dissolution tests were performed in distilled water and artificial intestinal fluid using the USP paddle II method. Compared with that of the commercial tablet (Zocor$^{(R)}$ 20 mg), the release of simvastatin from solid dispersion based-tablet was more efficient. Although the stability study is not complete, this solid dispersion system is expected to deliver poorly water-soluble drugs with enhanced bioavailability and less toxicity.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.369-372
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• 1998

Microbial insecticide formulations were prepared by liquid and semi-solid fermentations using Bacillus thuringiensis subsp. kurstaki, HL-106 (BTK-HL106), B. thuringiensis subsp. israelensis HL-63 (BTI-HL63) and B. sphaericus 1593 (BS-1593) strains. The liquid fermentation medium contained molasses 2%, dextrose 1.5%, peptone 2%, D-xylose 0.025%, CaCl$_2$ 0.1%, K$_2$HPO$_4$ 0.1%, KH$_2$PO$_4$ 0.1%, MgSO$_4$$.$7H$_2$O 0.03%, FeSO$_4$$.$7H$_2$O 0.002%, ZnSO$_4$$.$7H$_2$O 0.02%. The composition of the semi-solid fermentation medium was rice bran 45.2%, zeolite 31%, yeast powder 0.02%, corn powder 5%, dextrose 3%, lime 0.3%, NaCl 0.06%, CaCl$_2$ 0.02%, and H$_2$O 15.42%. Insecticide formulations produced in the liquid fermentation named BTK-HL106, BTI-HL63 and BS-1593 pesticides and those in the semi-solid fermentation were designated as BTK-HL106-1, BTI-HL63-1 and BS-1593-1 pesticides, respectively. The number of spore (endotoxin crystals) was 2.65${\times}$10$\^$9/ spores per $m\ell$ in the BTK-HL106 and 3.5${\times}$10$\^$10/ in the BTK-HL106-1 3.8${\times}$10$\^$9/ spores in the BTI-HL63 and 7.0${\times}$10$\^$10/ in the BTI-HL63-1, and 7.5${\times}$10$\^$9/ in the BS-1593 and 1.4${\times}$10$\^$10/ in the BS-1593-1. The spores in the BS-1593 formulation was produced two times more than the other formulations. The spores in the BTI-HL63-1 were contained twice than those in the BTK-HL106-1, and five times than those in the BS-1593-1. The results indicated that spore (endotoxin crystals) productions in the semi-solid fermentation increased about ten times than those in the liquid fermentations. $LC_{50}$s of the BTI-HL63 and BS-1593 were 4.5 $\mu\textrm{g}$, and those of the BTI-HL63-1 and BS-1593-1 were 1.5 $\mu\textrm{g}$. $LC_{50}$ of the BTK-HL106 was 1.5 mg and that of the BTK-HL106-1 was 0.9 mg. The $LC_{50}$s of the formulations in the semi-solid fermentations showed about two to three times higher than those in the liquid fermentations.

• Journal of Plant Biotechnology
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• v.35 no.1
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• pp.75-80
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• 2008

In vitro culture of shoot tip of garlic (Allium sativium L. cv. Seosan) was carried out to find medium condition of the induction of multiple shoots and bulbing for muliproduction of virus-free seed bulbs. For this work, tank culture was introduced. In shoot tip culture on MS solid medium the induction of multiple shoots and bulbing were better by adding 3% sucrose than 8%. Supplementation with 2mg/L 2ip and 0.2 mg/L IAA in this medium was effective. Three point three shoots including 2.7 bulbs were formed from a shoot tip after cultivation for 30 days on this medium. Bulbing of garlic in liquid culture with plastic water tank of 20L supplied air at the side of the lower part was better by adding 3% sucrose than 8% by subculture for 45 days with shoots obtained from shoot tip culture for 30 days on soid MS medium. Shoot growth was vigorous at 3% sucrose however bulb growth was more effective on the medium of 8% sucrose. Because of the effectiveness on solid medium added 3% sucrose, 2 mg/L 2ip and 0.2 mg/L IAA for initial production of multi-shoot in stem tip culture and the effectiveness in liquid culture with water tank for growth of bulbs, the method of two-step culture could be introduced for the multiple production of seed bulb of high quality. It was more desirable by supply of 0.2 mg/L BA and 0.02 mg/L NAA at tank culture time. But growth of the bulbs became poor by increasing concentration of NAA of the medium.

• Coupled systems mechanics
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• v.9 no.4
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• pp.343-358
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• 2020

The present research deals with the time-harmonic deformation in transversely isotropic magneto thermoelastic solid with two temperature (2T), rotation due to inclined load and laser pulse. Generalized theory of thermoelasticity has been formulated for this mathematical model. The entire thermo-elastic medium is rotating with uniform angular velocity and subjected to thermally insulated and isothermal boundaries. The inclined load is supposed to be a linear combination of a normal load and a tangential load. The Fourier transform techniques have been used to find the solution to the problem. The displacement components, stress components, and conductive temperature distribution with the horizontal distance are computed in the transformed domain and further calculated in the physical domain using numerical inversion techniques. The effect of angle of inclination of normal and tangential load for Green Lindsay Model and time-harmonic source for Lord Shulman model is depicted graphically on the resulting quantities.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.135-137
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• 2014

Excess enthalpy flame propagating an porous inert medium, which recirculate exhaust heat to the upstream cold mixture, is theoretically analyzed. Using the activation-energy asymptotics, the flame structure is divided into the thin reaction and the gas-phase preheat zone, as is traditionally done. Ahead and behind of the two, there exist an outer preheat zone, where heat is convectively transferred from solid to gas, and a downstream re-equilibrium zone, where thermal equilibrium between phases is established. Asymptotic solutions of species and energy equations in each zone are obtained and then matched to each other, and finally the mass burning rate is obtained as a function of the flame propagation velocity with respect to the solid phase and physical properties of gas and solid.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.379-381
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• 2009

The simulation model for metal-supported Solid Oxide Fuel Cell(SOFC) is developed in this study. Open circuit voltage is calculated using Nernst equation and Gibbs free energy is required by thermodynamic. The exchange current densities are compared with experimental results since exchange current density is most effective factor for the activation loss. Liu's study is used for the exchange current density of cathode, BSCF, and Koide's result is applied for the exchange current density of anode, Ni/YSZ. For the ohmic loss, ionic conductivity of YSZ is described from Kilner's mode and the data are compared with Wanzenberg's experimental data. Diffusivity is an important factor for the mass transfer through the porous medium. Both binary diffusion and Knudsen diffusion are considered as the diffusion mechanism. For validation, simulation results at this work are compared with our experimental results.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1714-1716
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• 1998

The surface breakdown problem has plagued the development of high solid state for more than 30 years, but the physical basis for this flashover phenomenon is still not understood. The only way to overcome those problem and has a workable compact solid state switch is to passivate the surface by a solid state dielectric material, to coating/encapsulation the device in an insulting medium. In this paper, characteristics of flashover in high field Si-dielectric system behavior under high electric field is discussed.