• The Korea Journal of Herbology
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• v.22 no.2
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• pp.97-102
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• 2007

Objectives : This study presents a high performance liquid chromatography - electrospray ionization-mass spectrometer (HPLC-MS/MS) methods for the quantitative and qualitative analysis of various active components in Samul-tang, which is composed of four crude herbs. Methods : HPLC-ESI-MS/MS for the determinations of paeoniflorin and 5-HMF (5-hydroxymethyl 2-furaldehyde) in the Samul-tang, the separation method was performed on an COSMOS1L 5C18-AR-Il (2.0 X 150 mm I.D.) column by gradient elution with 0.1% acetic acid and 5% CH3CN in water (A)-0.1% acetic acid and 5% H20 in CH3CN (B) as the mobile phase at a flow-rate of 300 ${\mu}L/min$ with detection at quadrupole mass spectrometer. The all marker substances were always detected as the base peaks in the positive ion mode. Results : The paeoniflorin of Paeoniae Radix in Samul-tang showed a strong base peak [M+H2O]+ in the positive detection mode to give the following as; paeoniflorin (498.109 [M+H2O]+, 479.8 [M]+, 301 [M-glucose]+, 179.3 [glucose]+). Based on the HPLC retnetion time and MS of standard compounds confirmed the identity of active compounds in Rehmanniae Radix Preparata as follows; 5-HMF (127.0[M+H]+, 109.3 [M-OH]+) in the positive ion mode. Conclusion : According to the above results, HPLC-ESI-MS method permits assignment of tentative structures such as paeoniflorin and 5-HMF in the Samul-tang.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.145-151
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• 1986

Using a new conductometric method, dissociation constants of 3-cyano, 4-cyano, 3-amino and 4-aminopyridine were measured in the temperature range 15 ∼ 40${\circ}C$ and pressure up to 2500bar in aqueous media. This method is convenient to apply to the low dissociative acid and base but have to do tedious extrapolating procedure for the ionic conductance in elaborated temperatures and pressures and have to know any reference dissociation constant. The measured dissociation constants were increased as the temperature increase but decreased as the pressure increase. From the constants, various thermodynamic properties were evaluated and discussed for the dissociation reactions.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.138-144
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• 2011

The transport phenomena of electron and ion around the electrode have been analyzed, herein the computational program to simulate the electrochemical signal of cyclic voltammetry has been implemented. For the dominant mass-transfer system, the governing equation and its boundary conditions are confined to the semi-infinite diffusion model and the reversible reaction at the electrode. In order to obtain the numerical solutions of cyclic voltammetry, MATLAB was used for the explicit finite difference method. Experimental results from the cyclic voltammetry of electrochemical system(10 mM $K_3Fe(CN)_6$ and 0.1M KCl) upon the ITO glass substrate were compared with the numerical solutions. Present program explains the experimental results fairly well, where they approached the simulated ones closely with deceasing the scan rate. Furthermore, the effects of electrode area, electrochemical reaction constants and transfering coefficients in the cyclic voltammetry were discussed quantitatively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.233-240
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• 2006

One of the main factor that effects on the CN's value in SCS Curve Number method for the estimation of direct runoff is the antecedent soil moisture condition (AMC). It is also common to use the AMC-III in hydrologic practice, which provides the largest runoff as possible. In this paper, AMC defending on the rainfall characteristics is analyzed using daily rainfall data at rainy season (June~September) of the Seoul station from 1961 to 2002. The probability mass function of AMC is also investigated to analyze the variation of AMC based on climate change, scenarios from several General Circulation Model (GCM) predictions. As a results we can find that the occurrence of AMC-I is reduced, and AMC-III is increased, whereas AMC-II does not change.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.65-71
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• 1988

In this study, the method of adsorption by activated carbon in the removal of Hg(II) ion in waste water was treated. The influence of kinds of activated carbon and effect of temperature and the influence of coexistent salt on adsorption rates, the influence of pH in the adsorption, equilibrium and adsorption of mercury from activated carbon were investigated. From the adsorption on activated carbon of mercury(II) ion in the presence of cyanide or thiocyanate ion was found that mercury(II) was easily adsorved onto the activated carbon in the form of complex artion such as Hg(CN)$_4^{2-}$, Hg(SCN)$_4^{2-}$ respectively. ZnCl$_2$ activation method had a higher adsorptive ability than steam activation method in adsorption of Hg on activated carbon. Activated carbon adsorbed iodide ion is very effective on adsorption of Hg.

• Water Engineering Research
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• v.4 no.4
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• pp.193-202
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• 2003

SWAT model was applied to estimate daily stream flow for Yongdam and Bocheong watersheds in Korea. The model was calibrated and validated for the two watersheds and a new routine was added to analyze runoff process in paddy fields. The model efficiencies for two watersheds were 0.77 and 0.65 for the calibration period, and 0.76 and 0.50 for the validation period, respectively. It showed that water balance method simulated the runoff from paddy fields more precisely than CN method in SWAT. As results, the SWAT model is applicable to Korean watersheds, and more accurate estimation is possible using daily water balance method in paddy fields.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.58.2-58.2
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• 2020

We present a method for determining the abundance ratio of nitrogen to iron ([N/Fe]) from low-resolution (R~2000) stellar spectra from large spectroscopic surveys such as Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The basic idea of the method is to match a grid of synthetic spectra with an observed spectrum in the CN band region around 3883 Å. To calibrate our estimate of [N/Fe], we make use of the giants observed in Apache Point Observatory Galaxy Evolution Experiment (APOGEE), which are also observed in the SDSS. This method will be applied to the Galactic halo stars to determine [N/Fe], and the measured nitrogen abundance ratios will be used to investigate the C-N anti-correlation, which is observed in globular clusters, to trace their origin with their kinematic properties.

• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.293-301
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• 2011

The material of the dental prosthesis was required bio-compatibility for biological, chemical, and physical stabilities. This study was conducted the stability evaluation of mechanical, biological characteristics through comparing Co-Cr alloy(SC group), Ti alloy(ST group) made by the selective laser melting method with Co-Cr alloy(CC group), Ni-Cr alloy(CN group) made by the casting method. Modulus of elasticity for mechanical characteristic evaluation was measured by the tensile test. And we conducted the release material analysis using lactic acid-NaCl solution for the evaluation of biological stability and were observed cytotoxicity through the content of this release medium. Taking these results into account, the Co-Cr alloy made by the selective laser melting method was observed modulus of elasticity higher than he Co-Cr alloy made by the casting method. And the Co-Cr alloy made by the selective laser melting method had more superior biological stability than the other groups as the result of cytotoxicity evaluation through the release material analysis. By this results, we think that alloys made by the selective laser melting method can be applied as materials for making the dental prosthesis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2431-2442
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• 1994

In this paper the efficient space marching Viscous Shock Layer and Parabolized Navier-Stokes method have been applied to study the complex 3-D hypersonic equilibrium chemically reacting flowfilelds over sphere-cone($10^{\circ}$) vehicle at low angles of attack($0^{\circ}~5^{\circ}), Mach 20, and an altitude of 35km. The current bluntbody/afterbody space marching numerical method predicts the complex flowfields accurately and efficiently even on a small computer. The shock thickness from equilibrium air model is thinner than that from the perfect gas model. The windside wall heat-transfer rate, pressure and skin friction force were increased significantly when compared with those of leeside. The CA, CN, CM were increased almost linearly with the angle of attack in this region. The wall pressure, heat transfer, skin friction and axial force coeffient from equilibrium model were much higher than those from perfect gas model. The center of pressure moved forward with the increase of angle of attack.

• Journal of the Korean Society of Tobacco Science
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• v.12 no.2
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• pp.77-83
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• 1990

This study was conducted to develop the method of hydrocarbon analysis and investigate hydrocarbon contents in flue-cured and burley tobacco leaves harvested in Korea and U.S.A. Tobacco leaf was extract with hexane in soxhlet apparatus. Hydrocarbon was fractionated from hexane extract by silica gel column chromatography, and then separated and indentified by GC, GC/MS using SE-54 fused silica capillary column. The developed method was feasible to analyze neophytadiene, normal and branched hydrocarbons from Clo to Cn. The result of recovery test was decade 99%, eicosane 100%, triacontane 102%. The major hydrocarbon of tobacco leaves were neophytadiene, nC3l, iC31, nC33, aC33, aC32, aC30 and nC29. The amount of total hydrocarbon in burley and flue-cured tobacco leaves harvested in U.S.A. and Korea were 4591, 2931, 2929 and 3015$\mu\textrm{g}$/g, respectively.