• Korean Journal of Pharmacognosy
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• v.41 no.1
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• pp.62-66
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• 2010

In result of analysis for the content determination of ursolic acid(UA) and oleanolic acid(OA) in extract of Eriobotryae folium using HPLC with UV detector, UA in chloroform extract of Moo-mok variety was showed highest content(2.7843 mg/g). And OA in ethyl acetate extract of Dae-bang variety was showed highest content(0.5898 mg/g). These result suggest that direct extraction using organic solvent(chloroform or ethyl acetate) was useful method for rapid quantitative analysis of UA and OA without preprocessing such as drying or fractionation.

• Nuclear Engineering and Technology
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• v.1 no.1
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• pp.33-38
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• 1969

Determinations of the isotopic contents of U$^{235}$ and U$^{238}$ in ten uranium samples containing 0.72-89.70 at % U$^{235}$ were carried out in two ways utilizing high resolution Ge (Li) gamma-ray spectrometer. One method is based upon the fact that the intensity of 185.5 kev gamma-ray vary linearly with U$^{235}$ content for a given geometry. Another method applied for the direct determination of the U$^{235}$ / U$^{238}$ isotopic ratios is the precision gamma-ray spectrometric analysis of reactor irradiated uranium samples after allowing a fixed cooling time for one hour. The results obtained by both methods well agree with the values calculated from the isotopic contents of highly enriched original uranium samples measured by mass spectrometer. The precision obtained was well below 5% for most of the isotopic ratios investigated.

• Structural Engineering and Mechanics
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• v.20 no.3
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• pp.279-292
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• 2005

In this study, element loading matrices are defined for static application of classical M$\ddot{u}$ller-Breslau principle to finite element method. The loading matrices are derived from existing element matrices using Betti's law and known governing equations of F.E.M. Thus, the ordinates of influence lines and influence surfaces may be easily obtained from structural analysis for the loading matrices derived from governing equations, instead of through introduced unit force or displacement techniques. An algorithm for a computer program and comparative numerical examples are also presented to illustrate the procedure for determination of influence line and surface ordinates.

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1127-1132
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• 2006

A new salicylate-selective electrode based on the complex N,N'-1,4-butylene bis(3-methyl salicylidene iminato) copper(II) as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of 59.1 ${\pm}$ 1.0 mV/decade and a linear range of $1.0\;{\times}\;10^{-6}$-1.0 M for salicylate. The limit of detection was $5.0\;{\times}\;10^{-7}$ M. It has a fast response time 10 s and can be used for more than three months. The selective coefficients were determined by the fixed interference method (FIM) and could be used in the pH range 4.5-10.5. It was employed as an indicator electrode for direct determination of salicylate in pharmaceutical samples.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.593-595
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• 1995

X-Ray Diffraction method that gives direct information about the deformation of crystal lattice is used for the determination of profiles of the residual stress along the depth of heavily boron doped silicon. The residual stress distribution is obtained by XRD method as measuring the deformation of the front surface of the $p^+$ silicon layer fabricated through different etch time. It is determined that the compressive residual stress exists in the most region except the font surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1048-1052
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• 2003

This study aims to derive frequency weighting curves for the estimation of driver's discomfort by steering wheel vibration in the vertical and rotational direction with respect to a steering column. Subjective tests for the determination of equal sensation curves, inverse of frequency weighting curves, for the two kinds of vibrations were performed using the sinusoidal signals with reference amplitudes from 0.2m/s$^2$ to 0.4 m/s$^2$ in the frequency range from 5㎐ to 100㎐. Twelve subjects joined at the tests, and median values of the twelve judgments were used to determine the frequency weighting curves. Second experiment was followed to determine relative magnitude between the two frequency weighting curves by direct comparison of discomfort due to the two kinds of vibrations at 50㎐, which showed discomfort by the rotational vibration was 1.5 times of that by the vertical vibration.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.277-279
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• 1976

A potentiometric titration method has been developed for the titration of copper with 2,5-dimercapo-1,3,4-thiadizole in aqueous solution using a silver electrode as an indicator electrode vs. the standard calomel electrode as a reference electrode. The 2,5-dimercapto-1,3,4-thiadiazole is very sensitive reagent for copper, which has been found to be highly selective for potentiometric determination of copper. Direct titration of trace amount of copper (0.02${\sim}$0.1 mg) is possible in the presence of a number of foreign ions in aqueous solution containing potassium hydrogen phthalate and sodium fluoride as masking agent under atmosphere.

• Journal of Preventive Medicine and Public Health
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• v.16 no.1
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• pp.193-198
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• 1983

In the determination of organic solvents in workplaces direct reading tube method have been used in Korea for decades. But this method is less accurate and couldn't measure TWA(Time Weighted Average) for 8 hours. Authors tried to detect Toluene concentration in S factory by using charcoal tube according to NIOSH method. The concentration was 158.8ppm. We propose this charcoal tube method should be substituted to get accurate results and to protect employee in workplaces related with solvents.

• Korean Journal of Pharmacognosy
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• v.31 no.4
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• pp.416-420
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• 2000

Ursolic acid was isolated from Prunellae Herba (Prunella vulgaris var. lilacina) and identified by direct comparison with an authentic sample. A method of analysis for the evaluation of ursolic acid was developed based on extraction of ground plant material, followed by quantitative determination using capillary gas chromatography of the TMS derivative. Quantitative analysis by GC after derivatisation under mild silylating conditions showed 0.31% ursolic acid in 20 samples collected throughout regions of Korea while no ursolic acid was detected in the samples of the whole plant of Thesium chinense, a substitute for Prunellae Herba in southern regions of Korean peninsula.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.696-700
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• 1999

A method has been developed for the determination of trace anion impurities in concentrated hydrogen peroxide. The method involves on-line decomposition of hydrogen peroxide, ion chromatographic separation and subsequent suppressed-type conductivity detection. H2O2 is decomposed in Pt-catalyst filled Gore-Tex membrane tubing and the resulting aqueous solution containing analytes is introduced to the injection valve of an ion chromatograph for periodic determinations. The oxygen gas evolving within the membrane tubing escapes freely through the membrane wall causing no problem in ion chromatographic analysis. Decomposition efficiency is above 99.99% at a flow rate of 0.4mL/min for a 30% hydrogen peroxide concentration. Analytes are quantitatively retained. The analysis results for several brands of commercial hydrogen peroxides are reported.