• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.309-314
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• 2015

Adsorption of brilliant blue FCF dye from aqueous solution using coconut shell based activated carbon was investigated. Batch experiments were carried out as function of adsorbent dose, initial concentration, contact time and temperature. The equilibrium adsorption data were analyzed by Langmuir and Freundlich model. The results indicate that Freundlich model provides the best correlation of the experimental data. Base on the estimated Freundlich constant (1/n=0.129~0.212), this process could be employed as effective treatment method. Adsorption kinetics experimental data were modeled using the pseudo-first-order and pseudo-second-order kinetic equation. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. Base on the negative Gibbs free energy value (-4.81~-10.33 kJ/mol) and positive enthalpy value (+78.59 kJ/mol) indicate that the adsorption is spontaneous and endothermic process.

• The Journal of Engineering Geology
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• v.30 no.2
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• pp.147-160
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• 2020

Unsaturated hydraulic conductivity of near-surface unconsolidated layers depends on the physical properties and water content of the unconsolidated layers. So far, many studies have been conducted on the unsaturated hydraulic conductivity of near-surface unconsolidated layers. However, researches on hydraulic conductivity of unsaturated fractured rocks have been relatively rare. In relation to the construction of a low/intermediate level radioactive waste surface-disposal facility, this study compared and analyzed van Genuchten parameters (α, n) in the laboratory and the hydraulic conductivity obtained in field tests for fractured hornfels at a radioactive-waste disposal site of Korea. The relationship between the field hydraulic conductivity and van Genuchten parameters using data from the ten depth intervals of three boreholes resulted in that the correlation coefficient (R) between the hydraulic conductivity and the van Genuchten parameter α was 0.7607, showing positive correlation whereas the R between the hydraulic conductivity and the van Genuchten shape-defining parameter n was -0.8720, showing negative correlation. Hence, this study confirmed the relationship between the field hydraulic conductivity and the van Genuchten unsaturated functions for the unsaturated fractured hornfels.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.819-825
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• 2006

The objective of the present study is to verify the validity of a new truss model for evaluating the contribution by arch action to shear resistance in shear-critical reinforced concrete beams. The new truss model is based on the relationship between shear and bending moment in a beam subjected to combined shear and bending. The compatibility condition of the shear deformation that deviates from Bernoulli bending plane is formulated utilizing the smeared truss idealization with an inclined compression chord. The Modified Compression Filed Theory is employed to calculate the shear deformation of the web, and the relative axial displacements of the compression and the tension chord by the shear flow are also calculated. From this shear compatibility condition in a beam, the shear contribution by the arch action is numerically decoupled. Then the validity of the model is examined by applying the model to some selected test beams in literatures. On the basis of the analytical results, the contribution by the web to shear resistance can be constant and have an excellent linear correlation with the web reinforcement ratio. The present decoupling approach may provide a simple way for the assessment of the role of each parameter or mechanism that affects the ultimate shear behavior of reinforced concrete beams.

• Environmental and Resource Economics Review
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• v.23 no.2
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• pp.187-224
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• 2014

We present key issues to consider in estimating damages from price-fixing cases and then apply the procedure addressing those issues to a transportation fuel market. Among the five methods of overcharge calculation, the regression analysis incorporating the yardstick method is the best. If the price equation relates the domestic price to the foreign price and the exchange rate as in the transportation fuel market, the functional form satisfying both logical consistency and modeling flexibility is the log-log functional form. If the data under analysis is of time series in nature, then the ARDL model should be the base model for each market and the regression analysis incorporating the yardstick method combines these ARDL equations to account for inter-market correlation and arrange constant terms and collusion-period dummies across component equations appropriately so as to identify the overcharge parameter. We propose a two-step test for the benchmarked market: (a) conduct market-by-market Spearman or Kendall test for randomness of the individual market price series first and (b) then conduct across-market Friedman test for homogeneity of the market price series. Statistical significance is the minimal requirement to establish the alleged proposition in the world of uncertainty. Between the sensitivity analysis and the model selection process for the best fitting model, the latter is far more important in the economic analysis of damage in price-fixing litigation. We applied our framework to a transportation fuel market and could not reject the null hypothesis of no overcharge.

• Korean Journal of Agricultural Science
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• v.22 no.1
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• pp.103-109
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• 1995

The model foods were prepared by simulating mositure, protein and starch, and they were heated for 30 mins, at $80^{\circ}C$ and then cooled at $25^{\circ}C$ in water bath. Their rheological properties were investigated by the use of Brookfield wide-gap rotational viscometer at $30{\sim}60^{\circ}C$, and the rotation speed ranged from 0.6 to 6 rpm and solid content ranged from 8% to 11%, the results obtained were as follows. 1. All the model foods ($P_1S_3$, $P_2S_2$, $P_1S_1$, $P_2S_1$, $P_3S_1$, $P_4S_0$) exhibited pseudoplastic behaviors with yeild stress and were thixotropic foods which showed time - dependent structural decays, but the starch food of 8 ~ 11 % solid content did not show the flow behavior. 2. The correlation between the rheological parameters and the protein content of model foods in various moisture content did not appeared a constant relationship. 3. The change of shear stress against shear rate in high starch foods was larger than that in high protein foods and the structure at initial shear time was decayed with a quatic equation according to the Tiu's Model and structural decay was in parallel with the increase of shear rate. 4. The temperature dependency of the apparent viscosity of $P_1S_2$, and $P_2S_1$ was fully expressed by Arrhenius equation and activation energies of their food were 2.35 and $1.34Kcal/g{\cdot}mol$, respectively.

• The Korean Journal of Financial Management
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• v.26 no.2
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• pp.155-180
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• 2009

This study is to estimate and compare hedging effectiveness in emerging currency and advanced currency futures markets. Emerging currency futures includes Korea won, Mexico peso, and Brazil real and advanced currency futures is Europe euro, British pound, and Japan yen. Hedging effectiveness is measured by comparing hedging performance of the naive hedge model, OLS model, error correction model and constant condintional correlation bivariate GARCH(1, 1) hedge model based on rolling windows. Analysis data is used daily spot and futures rates from January, 2, 2001 to March. 10, 2006. The empirical results are summarized as follows : First, irrespective of hedging period and model, hedging using Korea won/dollar futures reduces spot rate's volatility risk by 97%. Second, Korea won/dollar futures market produces the best hedging performance in emerging and advanced currency futures markets, i.e. Mexico peso, Brazil real, Europe euro, British pound, and Japan yen. Third, there are no difference of hedging effectiveness among hedging models.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.112-118
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• 2018

Adsorption equilibrium, kinetic and thermodynamic parameters of a brilliant green from aqueous solutions at various initial dye concentration (10~30 mg/L), contact time (1~24 h) and temperature (298~318 K) on zeolite were studied in a batch mode operation. The equilibrium adsorption values were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich model. The results indicate that Langmuir and Freundlich model provides the best correlation of the experimental data. Base on the estimated values of Langmuir dimensionless separation factor ($R_L=0.041{\sim}0.057$) and Freundlich constant (1/n=0.30~0.47), this process could be employed as effective treatment method. calculated values of adsorption energy by Dubinin-Radushkevich model were 1.564~1.857 kJ/mol corresponding to physical adsorption. The adsorption kinetics of brilliant green were best described by the pseudo second-order rate model and followed by intraparticle diffusion model. Thermodynamic parameters such as activation energy, free energy, enthalpy and entropy were calculated to estimate nature of adsorption. negative Gibbs free energy (-10.3~-11.4 kJ/mol), positive enthalpy change (49.48 kJ/mol) and Arrehenius activation energy (27.05 kJ/mol) indicates that the adsorption is spontaneous, endothermic and physical adsorption process, respectively.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.43-48
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• 2005

To search of a new porcine pheromonal odorants for biostimulation control system technologies to offer a potentially useful and practical way to improve reproductive efficiency in livestock species, the holographic quantitative structure activity relationship (HQSAR) model between odorants, 2-phenoxytetrahydrofurane (A), 2-cyclohexyl-oxytetrahydrofurane (B), derivatives and binding affinity constants (p[Od.]/sub 50/) for porcine odorant-binding protein (pOBP) as receptor of pig pheromones were derivated and disscused. The binding affinity constants of cyclohexyl substituents (A) for pOBP were higher (A>B) than that of phenyl substituents (B). It was revealed that the optimum HQSAR model XI using PLS analyses had a fragment length (5∼8) with chirality at 5 components and hologram length 97 bin, which had a cross-validated q²(predictablities) of 0.916, and a conventional correlation coefficient r² (fitness) of 0.988, respectively. From the atomic contribution, the C3 and C5 atom in 2-oxyfuryl group contributed to binding affinity constants, whereas the central carbon atom in tert-butyl group on the cyclohexyl ring and the C4 atom of furyl group parts showed no contribution.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.845-851
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• 1995

To improve the utilization of pear in its processing, the cloudy and clear juice concentrates were prepared and their rheological properties were investigated in the range of temperatures($5{\sim}60^{\circ}C$) and concentrations($15{\sim}60^{\circ}Brix$). Pear juice concentrates showed flow behavior close to Newtonian fluids. Their flow behavior was also explained by applying Power law model and Herschel-Bulkley model. Flow behavior index did not have good correlation with concentration, but decreased with the increase of temperature, showing pseudoplastic properties. Consistency index increased with the increase of concentration and with the decrease of temperature. The effect of temperature and concentration on the apparent viscosity at 1500 1/s shear rate was examined by applying Arrhenius equation. The activation energy for flow of the cloudy and clear pear juice concentrates increased from $1.5140{\times}10^4\;to\;3.4141{\times}10^4\;J/kg{\cdot}mol$, and from $1.4762{\times}10^4\;to\;3.4963{\times}10^4\;J/kg{\cdot}mol$ with the increase of concentration, respectively. The influence of temperature on the apparent viscosity was more pronounced at higher concentration. And the concentration-dependent constant A decreased from $0.0789\;to\;0.0484^{\circ}Brix^{-1}$, and from $0.0786\;to\;0.0476^{\circ}Brix^1$ with the increase of temperature, respectively.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.353-356
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• 2012

We present new constraints on the cosmic optical background (COB) obtained from an analysis of the Pioneer 10/11 Imaging Photopolarimeter (IPP) data. After careful examination of the data quality, the usable measurements free from the zodiacal light are integrated into sky maps at the blue (${\sim}0.44{\mu}m$) and red (${\sim}0.64{\mu}m$) bands. Accurate starlight subtraction was achieved by referring to all-sky star catalogs and a Galactic stellar population synthesis model down to 32.0 mag. We find that the residual light is separated into two components: one component shows a clear correlation with the thermal $100{\mu}m$ brightness, whilst the other shows a constant level in the lowest $100{\mu}m$ brightness region. The presence of the second component is significant after all the uncertainties and possible residual light in the Galaxy are taken into account, thus it most likely has an extragalactic origin (i.e., the COB). The derived COB brightness is ($(1.8{\pm}0.9){\times}10^{-9}$ and $(1.2{\pm}0.9){\times}10^{-9}\;erg\;s^{-1}\;cm^{-2}\;sr^{-1}\;{\AA}^{-1}$ in the blue and red spectral regions, respectively, or $7.9{\pm}4.0$ and $7.7{\pm}5.8\;nW\;m^{-2}\;sr^{-1}$. Based on a comparison with the integrated brightness of galaxies, we conclude that the bulk of the COB is comprised of normal galaxies which have already been resolved by the current deepest observations. There seems to be little room for contributions from other populations including "first stars" at these wavelengths. On the other hand, the first component of the IPP residual light represents the diffuse Galactic light (DGL)-scattered starlight by the interstellar dust. We derive the mean DGL-to-$100{\mu}m$ brightness ratios of $2.1{\times}10^{-3}$ and $4.6{\times}10^{-3}$ at the two bands, which are roughly consistent with previous observations toward denser dust regions. Extended red emission in the diffuse interstellar medium is also confirmed.