• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.5-12
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• 1991

The dielectric properties of natural rubbers for electric safety are very important to investigate the molecular structure. The electric safety characteristics of the dielectric absorption in aging vulcanized natural rubber were studied in the range of frequency from 1$\times$10$^3$［Hz］to 3.2$\times$10$^3$［Hz］l at the temperature of 23［$^{\circ}C$］. As the results, it has been confirmed that in the case of aging natural rubber of above 2 phr the specimens exhibit two kinds of dielectric losses due to the dipole polarization by impurities and sulfurs, and of raw rubber exhibit the kind of losses due to the dipole polarization. Rurthermore, dielectric loss maximum tansspectrum in high freguency region for electric safety, which removed to the low freguency according to increasing sulfur, depends greatly on sulfur.

• Journal of the Korean Applied Science and Technology
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• v.16 no.3
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• pp.199-203
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• 1999

The symmetric benzoxazolo carbocyanine is of industrial importance as green-sensitizing dye in the spectral sensitization of emulsion microcrystals in positive paper and negative film-making. The stability on the solvents of benzoxazolo carbocyanine dye was measured by UV-Vis spectrophotometer, and then all of solvents were stabilized sensitizer. The maximum absorption peak range in methanol, acetonitrile, acetone, DMF, dichloromethane, chloroform solvents was $501nm{\sim}511nm$. But it was identified that only methanol can be used to photographic emulsion. The photographic characteristics have contrast of 2.8, speed of 50-55$(lux{\cdot}sec)^{-1}$, fog of 0.07-0.08, respectively.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.10a
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• pp.246.2-246
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• 1979

Lactobacillus lactis cell was markedly damaged when shocked by freezing and freeze-drying. The supernatant of shocked cells in 1％ phosphate buffer (pH7.3) showed a maximum u.v. absorption spectra at 260nm after further incubation for 90min at $37-^{\circ}C.$ The leakage of cellular constituents by shocking could be prevented by dimethyl sulfoxide, glycerol, dextrose and $MgCl_2.$ Among them, $MgCl_2$ showed the preventing effect before and after freezing wh-ereas the rests, only before the treatment. This leakage was proved not to be related to the cellular repairing mechanism.

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.57-64
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• 1997

The symmetric naphthothiazolo carbocyanine is of industrial importance as green-sensitizing dye in the spectral sensitization of emulsion microcrystals in negative film-making. In this study, green-sensitizing dye was prepared by the reaction of 2-methyl-3-sulfopropyl-5-phenyl-benzoxazolium(inner salt) with triethyl orthoacetate in the presence of triethylamine. The product was identified by using various analytical tools such as Elemental analyzer, IR spectrophotometer, UV-Vis spectrophotometer, $^1H$-NMR spectrometer, TGA and DSC. The maximum absorption peak in methanol solvent was 502nm. Therefore, it was concluded that benzoxazolo carbocyanine dye can be used as green-sensitizing dye for the spectral sensitization of photographic emulsion.

• Journal of KSNVE
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• v.9 no.6
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• pp.1218-1226
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• 1999

In this paper, the extended Biot's semilinear model was developed. Combining the extended Biot model with the dynamic equation yields the nonlinear wave equation in poproelastic sound absorbing materials. Both perturbation and matching techniques are used to find solutions for nonlinear wave equations. By comparing results between linear and nonlinear wave solutions, characteristics of nonlinear waves in poroelastic sound abosrbing materials have been studied. Nonlinear waves were found to be attenuated faster than the linear ones. A maximum amplitude of the nonlinear wave occurred near its surface boundaries and decay quickly with distance from the surface. It has also been found that, if the amplitudes of linear waves are known at the surface boundaries, those of nonlinear ones can be determined. This will be the basis of finding effects of nonlinearity on the absorption coefficient and the transmission loss.

• Journal of KSNVE
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• v.9 no.6
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• pp.1123-1130
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• 1999

A system which is composed of a membrane and an air cavity is studied. To analyze the low frequency characteristics of a single membrane-cavity system, a plane wave model is derived. The relations among system variables, such as tension, density and stiffness, are investigated. Absorption coefficient has a maximum value at a peak frequency. In addition, a membrane-cavity system absorbs the low frequency noise with a band around peak frequency. This band is primarily determined by damping effect of the system. Furthermore, a multiple membrane-cavity system is investigated by using the transfer matrix method. To show the practical applicability of the proposed model, extensive experiments were conducted. Results show that a multiple membrane-cavity system can have broader noise reduction in the low frequency range than single.

• Korean Journal of Pharmacognosy
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• v.1 no.2
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• pp.23-28
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• 1970

One of the indigeneous plants to this country, Syringa dilatata $N_{AKAI}$ (Oleaceae) is known in commerce as 'Ya-Jung-Hyang' (野丁香) and has been known to be of effect as bitter stomachics. Seasonal variations in the content of polyalcohols and free reducing sugars in leaves of this plant which contains syringin glycoside, mannitol and free reducing sugars etc. were studied. Application of chromotropic acid to formaldehyde which was obtained from polyalcohols and reducing sugars by treatment with periodic acid results in reddish violet coloration and the solution has absorption maximum at wave length $570m\;{\mu}$. By the use of ionic exchange resin chromatography, poyalcohols were separated from the above mixture. The content of polyalcohols of this plant was plentiful in the growing season while that of free reducing sugars was decreasing vice versa.

• Analytical Science and Technology
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• v.8 no.4
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• pp.469-475
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• 1995

Di-2-pyridylmethanon 2-thiophenecarboxylie hydrazone(DPMTCH) was synthesized and used as a chromogenic reagent in the spectrophotometric determination of nickel in steel. The proton disc spectrophotometrically, were $pK_{a1}= 2.66$ and $pK_{a2}= 10.98$ ${\mu}=0.5(NaCl)$. Nickel(II) reacts with DPMTCH to form a 1:2 metal-2-ligand ratio complex, the xylene solution of which has an absorption maximum at 417 nm. Beer's law is obeyed over the range $0-1.17\;mg\;ml^{-1}$ of nickel(II). The molar absorptivity of the nickel(II) complex is $4.17{\times}10^4l\;mol^{-1}\;cm^{-1}$. The precision of the method was estimated for 4.7 mg of nickel(II), the coefficient of variation for 15 replicate determinations being 0.34%.

• Journal of Pharmaceutical Investigation
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• v.4 no.1_2
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• pp.1-6
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• 1974

S-Benzylthiuronium chloride reacts with ethylene glycol, derived from hydrolysis of the fluorides, to produce a crystalline substances. Using this, the fluorides can be indentified by measuring melting point. And when the zirconium-alizarin solution reacts with ethylenefluoro hydrin or ${\beta}-fluoroethyl$ acetate, the red-violet color disappears to produce a yellow dye, which exhibits absorption maximum at about $530\;m{\mu}$ using the 250-microgram standard. Using these properties, the fluorine compounds can be determined conveniently by this method.

• Structural Engineering and Mechanics
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• v.44 no.3
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• pp.325-337
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• 2012

In this article, the multi-objective optimization of cylindrical aluminum tubes under axial impact load is presented. The specific absorbed energy and the maximum crushing force are considered as objective functions. The geometric dimensions of tubes including diameter, length and thickness are chosen as design variables. D/t and L/D ratios are constricted in the range of which collapsing of tubes occurs in concertina or diamond mode. The Non-dominated Sorting Genetic Algorithm-II is applied to obtain the Pareto optimal solutions. A back-propagation neural network is constructed as the surrogate model to formulate the mapping between the design variables and the objective functions. The finite element software ABAQUS/Explicit is used to generate the training and test sets for the artificial neural networks. To validate the results of finite element model, several impact tests are carried out using drop hammer testing machine.