• Bulletin of the Korean Chemical Society
• /
• v.21 no.5
• /
• pp.503-509
• /
• 2000

The solvent effects on the relative free energies of solvation and the difference in partition coefficients (log P) for $Rb^+$ to $K^+$ mutation in several solvents have been investigated using Monte Carlo simulation (MCS) of statistical perturbation theory(SPT). In comparing the relative free energies for interconversion of one ion pair, $Rb^+$ to $K^+$, in $H_2O$(TIP4P) in this study with the relative free energies of the computer simulations and the experimental, we found that the figure in this study with the relative free energies of the computert simulations and the experimental, we found that the figure in this study is $-5.00\pm0.11$ kcal/mol and those of the computer simulations are $-5.40\pm1.9$, -5.5, and -5.4 kcal/mol. The experimental is -5.1 kcal/mol. There is good agreement among various studies, taking into account both methods used to obtain the hydration free energies and standard deviations. There is also good agreement between the calculated structural properties of this study and the simulations, ab initio and the experimental results. We have explained the deviation of the relationship between the free energy difference and the Onsager dielectric function of solvents by the electron pair donor properties of the solvents. For the $Rb^+$ and $K^+$ ion pair, the Onsager dielectric function of solvents (or solvent permittivity), donor number of solvent and the differences in solvation dominate the differences in the relative free energies of solvation and partition coefficients.

• Food Science and Biotechnology
• /
• v.14 no.4
• /
• pp.456-460
• /
• 2005

To enforce the maximum residue limit for residual hexane (0.005 g/kg) in commercially available Korean vegetable oil, convenient and accurate quantification methods were investigated. Using dual surrogate standards, pentane and heptane were dissolved in ethanol, and then added to hexane-tree sunflower oil for setting up the calibration curve. Gas Chromatograph-Flame Ionization Detector with a porous layer open tubular column, indicated good chromatographic separation of hexane from other inhibiting matrix components. The lowest calibration level was $0.5\;{\mu}g/g$, not exceeding a relative standard deviation of 10% (RSD%), and 1.0\;{\mu}g/g$ not exceeding a deviation of 22% RSD% using heptane as an internal standard for the Static headspace analysis by using a headspace auto-sampler and manual injection, respectively. The residual hexane was detected in nine of the samples among 87 vegetable oil samples purchased on the local market.

• New & Renewable Energy
• /
• v.7 no.2
• /
• pp.43-50
• /
• 2011

The only practical way to measure wind resource at high-altitude over 100 m above ground for a feasibility study on a high-rise building integrated wind turbine might be ground-based remote sensing. The remote-sensing campaign was performed at a 145 m-building roof in Jamsil where is a center of metropolitan city Seoul. The campaign aimed uncertainty assessment of Leosphere WindCube LIDAR and Scintec MPAS SODAR through a mutual comparison. Compared with LIDAR, the data availability of SODAR was about 2/3 at 550 m altitude while both showed over 90% under 400 m, and it is shown that the data availability decrease may bring a distortion of statistical analysis. The wind speed measurement of SODAR was fitted to a slope of 0.92 and $R^2$ of 0.90 to the LIDAR measurement. The relative standard deviation of wind speed difference and standard deviation of wind direction difference were evaluated to be 30% and 20 degrees, respectively over the whole measurement heights.

• Geotechnical Engineering
• /
• v.4 no.3
• /
• pp.5-18
• /
• 1988

This study aims at scrutinizing the relationships among the frequency distribution of voids the relative density and the shear strength for the three types of different granular materials. The main results summarized are as follows: (1) The frequency distribution of void ratio of glass beads can be approximated by the negative exponential distribution proposed by Shahinpoor (1981), while as the particle shape changes from spherical to angular the frequency of the denser voids decreases and the distributions are well presented by the beta distribution. (2) For all materials, the standard deviation of void ratio increases with decreasing both the relative density of the material and sphericity of particle. (3) It was found that shear strength of the material was a function of not only the mean void ratio and its standard deviation, but also of the shape of the probability density function of the distribution of void ratio. The more the frequency distribution of void inclines towards the denser voids, the higher the shear strength of the material and vice versa.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.2
• /
• pp.79-84
• /
• 1999

An image processing technology was developed to measure the dimension of nuclear fuel rods and the diameter of nuclear fuel rods was measured by this method. It was confirmed that parameters such as camera-to-specimen distance. camera location, light intensity and light characteristic would affect dimension measurement of nuclear fuel rods. The percent relative error and percent standard deviation of measuring the diameter of nuclear fuel rods using image processing method were 4.88%, ${\pm}3.34%$ while the percent relative error and percent standard deviation using conventional method were 12.7%, ${\pm}9.72%$, respectively. The accuracy of diameter measurement of nuclear fuel rods using image processing method was about 3 times as high as that using conventional method.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2002.11a
• /
• pp.59-62
• /
• 2002

Wavelength selection and prediction algorithm for determining hematocrit are investigated. A model based on the difference in optical density induced by the pulsation of heart beat is developed by taking approximation of Twersky's theory on the assumption that the variation of blood vessel size is small during arterial pulsing[1]. A device is constructed with a five-wavelength LED array as light source. The selected wavelengths are two isobestic points and three in compensation for tissue scattering. Data are collected from 549 out-patients who are randomly grouped as calibration and prediction sets. The range of percent hematocrit was 19.3∼51.8. The ratio of the variations of optical density between systole and diastole at two different wavelengths is used as a variable. We selected several such variables that show high reproducibility among all variables. Multiple linear regression analysis is made. The relative percent error is 8% and the standard deviation is 3.67 for the calibration set. The relative % error and standard deviation of the prediction set are 8.2% and 3.69 respectively. We successfully demonstrate the possibility of non-invasive hematocrit measurement, particularly, using the wavelengths below 1000nm.

• Journal of Ginseng Research
• /
• v.36 no.2
• /
• pp.205-210
• /
• 2012

For quality control of components in Korean red ginseng powder and extract, a new method for simultaneous quantification of 12 ginsenosides ($Rg_1$, Re, Rf, $Rh_1$, $Rg_2$[S], $Rg_2$[R], $Rb_1$, Rc, $Rb_2$, Rd, $Rg_3$[S], and $Rg_3$[R]) was studied. Compared to the official method for quantification of marker substances (ginsenosides $Rg_1$ and $Rb_1$), the proposed methods were guaranteed by in-house method validation. Several criteria such as linearity, specificity, precision and accuracy were evaluated. For red ginseng powder, recovery (averaging 95% to 105%) was calculated, and analysis of variance was carried out to estimate the relative standard deviation (0.20% to 2.12%). For red ginseng extract, the average recovery rate was 90% to 99% and the relative standard deviation was 0.39% to 2.40%. These results indicate that the proposed method could be used in the laboratory for determination of 12 ginsenosides in red ginseng powder and extract. In addition, this method was found to be suitable for quality control of ginseng products and potentially offer time and cost benefits.

• Analytical Science and Technology
• /
• v.32 no.2
• /
• pp.48-55
• /
• 2019

The simple and effective analytical method for the quality control of a novel scalp tonic formulation has been developed and optimized in terms of HPLC conditions and sample preparation method, meanwhile, the optimization of preparation condition was using response surface methodology (RSM) based on central composite design (CCD). Oleanolic acid was selected as marker compound because of its bioactivities for alopecia therapy. The developed analytical method and extraction condition were successfully qualified. Coefficient of determination ($r^2$) for the calibration was 0.9997 with a line passing through the origin point in the range of 0.1-100 mg/mL. The limit of detection (LOD) and the limit of quantitation (LOQ) were 17.5 ng/mL and 55.0 ng/mL, respectively. The intra-day and inter-day precision of the method were 0.5-1.4 % and 0.7-1.8 % in relative standard deviation, respectively, while those accuracy were 99.5-100.9 % and 100.0-102.2 %, respectively. The repeatability of oleanolic acid in samples ranged of 0.3-1.9 % based on peak area and 0.3-0.7 % for retention time. Recoveries from samples were 95.0-99.4 % with lower than 1.8 % in relative standard deviation. Overall, the developed analytical method will be used for quality control of this commercial scalp tonic products successfully.

• The Korean Journal of Applied Statistics
• /
• v.34 no.4
• /
• pp.589-597
• /
• 2021

In simple and multiple regression, there is a difference in the meaning of regression coefficients, and not only are the estimates of regression coefficients different, but they also have different signs. Understanding the relative contribution of explanatory variables in a regression model is an important part of regression analysis. In a standardized regression model, the regression coefficient can be interpreted as the change in the response variable with respect to the standard deviation when the explanatory variable increases by the standard deviation in a situation where the values of the explanatory variables other than the corresponding explanatory variable are fixed. However, the size of the standardized regression coefficient is not a proper measure of the relative importance of each explanatory variable. In this paper, the estimator of the regression coefficient in multiple regression is expressed as a function of the correlation coefficient and the coefficient of determination. Furthermore, it is considered in terms of the effect of an additional explanatory variable and additional increase in the coefficient of determination. We also explore the relationship between estimates of regression coefficients and correlation coefficients in various plots. These results are specifically applied when there are two explanatory variables.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.17 no.1
• /
• pp.31-42
• /
• 2007

Recently, concerns regarding indoor air quality in offices have continued to increase. Thirty offices in five metropolitan commercial buildings were surveyed from February to April 2004. Sampling was performed during normal business hours. Thermal comfort factors such as temperature and relative humidity, carbon dioxide ($CO_2$), carbon monoxide (CO), formaldehyde (HCHO), respirable dust, $PM_{10}$ were sampled and analyzed to determine the mean, standard deviation, range, and correlation for each of those parameters. The data was then compared to office as standard of Ministry of Labor, and guideline applicable to the indoor environment. The results represented that the temperature was slightly higher than the standard of American Society of Refrigerating and Air-Conditioning Engineers (ASHRAE), the relative humidity was lower that the standard of ASHRAE. The range of the 8-TWA concentration of $CO_2$ was 639 ~ 786 ppm, but 33.3% of the total thirty offices exceeded the 1000 ppm as ceiling concentration. The concentration of CO was less than 3 ppm, which was similar to that of offices in Japanese. The mean concentration of formaldehyde was 0.032 ppm, and only 2 % of total samples (193) exceeded the 0.1 ppm, standard of formaldehyde in office air. The concentration of respirable dust and $PM_{10}$ was not exceeded the standard of those parameters, $150{\mu}g/m^3$. The concentration of those parameters in the office air was statistically correlated.