• Journal of the Mineralogical Society of Korea
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• v.17 no.2
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• pp.157-168
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• 2004

The surface chemical properties of aqueous kaolinite and halloysite were studied using a potentiometric titration experiment and a computer program FITEQL3.2. Among the surface complexation models a constant capacitance model was selected for this study. The 2 sites - 3 p $K_{a}$ s model, in which the surfaces were assumed to have tetrahedral and octahedral sites, was reasonable for the description of the experimental data. The surface charges of both minerals were negative above pH of 4. The higher the pH, the lower the proton surface charge densities of both minerals. The ≡ $SiO^{[-10]}$ site played an important role in cation adsorption in acid and neutral pH range; whereas the ≡ Al $O^{[-10]}$ site was in an alkaline pH range. The optimized intrinsic constants of kaolinite, p $K_{a2(Si)}$$^{int}$, p $K_{al(Al)}$$^{int}$ and p $K_{a2(Al)}$$^{int}$ were 4.436, 4.564, and 8.461 respectively, and those of halloysite were 7.852, 3.885, and 7.084, respectively. The total Si and Al surface sites concentrations of kaolinite were 0.215 and 0.148 mM, and those of halloysite were 0.357 and 0.246 mM. The ratio of Si and Al surface site densities ([≡SiOH]:[≡AlOH]) of both minerals was 1 : 0.69. The total surface site density of kaolinite, 3.774 sites/n $m^2$, was 1.6 times larger than that of halloysite, 2.292 sites/n $m^2$./TEX>.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.345-351
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• 2008

Fe-impregnated activated carbon(Fe-AC) was prepared by Fe(III) loading on activated carbon(AC) in various preparation pH. In order to evaluate the stability of Fe-AC, dissolution of iron from Fe-AC in acidic conditions was measured. In addition, batch experiments were conducted to monitor the removal efficiency of copper by Fe-AC. Results of stability test for Fe-AC showed that the amount of extracted iron increased with contact time but decreased with increasing solution pH. The dissolved amount of iron gradually increased at solution pH 2 and finally 13% of the total iron loaded on activated carbon was extracted after 12 hr. However dissolution of iron was negligible over solution pH 3. Removal of Cu(II) by Fe-AC was greatly affected by solution pH and was decreased as solution pH increased as well as initial Cu(II) concentration decreased. Surface complexation modeling was performed by considering inner-sphere complexation reaction and using the diffuse layer model with MINTEQA2 program.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.3
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• pp.173-181
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• 2007

A three-dimensional ecological model (EMT-3D) was applied to Tokyo Bay for the simulation of PFOA. EMT-3D was calibrated with seawater analysis data obtained from the study area in 2004. The simulated results of dissolved PFOA were in good agreement with the observed values, with a correlation coefficient(R) of 0.7115${\sim}$0.8759 and a coefficient of determination $(R^2)$ of 0.5062${\sim}$0.7672. The results of sensitivity analysis showed that partition rate, adsorption rate and settling rate were important factors for PFOA in particulate organic matter. In the case of PFOA in phytoplankton, bioconcentration factor, uptake rate and partition rate were important factors. Therefore, the parameters must be carefully considered in the modeling. In the case of 50% and 80% total loads reduction, concentration of dissolved PFOA was shown to be lower than 20ng/L and 10ng/L, respectively. In the case of reduction of loads from rivers in each prefecture, Tokyo prefecture was found to have the most influence on the change of dissolved PFOA in surface water while Chiba prefecture was found to have the most influnce on the change of dissolved PFOA in bottom water.

• Journal of Korea Water Resources Association
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• v.46 no.11
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• pp.1115-1128
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• 2013

The purpose of this study is to evaluate the suspended solids and eutrophication processes relationships in Chungju lake using CE-QUAL-W2, two-dimensional (2D) longitudinal/vertical hydrodynamic and water quality model. For water quality modeling, the lake segmentation was configured as 7 branches system according to their shape and tributary distribution. The model was calibrated (2010) and validated (2008) using 2 years of field data of water temperature, suspended solids (SS), total nitrogen (TN), total phosphorus (TP) and algae (Chl-a). The water temperature began to increase in depth from April and the stratification occurred at about 10 m early July heavy rain. The high SS concentration of the interflow density currents entering from the watershed was well simulated especially for July 2008 heavy rainfall event. The simulated concentration range of TN and TP was acceptable, but the errors might occur form the poor reflection for sedimentation velocity of nitrogen component and adsorption-sediment of phosphorus in model. The concentration of Chl-a was simulated well with the algal growth patterns in summer of 2010 and 2008, but the error of under estimation may come from the use of width-averaged velocity and concentration, not considering the actual to one side inclination by wind effect.

• KSBB Journal
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• v.21 no.3
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• pp.224-229
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• 2006

FEMLAB is a powerful interactive environment for modeling, solving all kinds of scientific and engineering problems based on partial differential equations(PDEs). Separation process of chiral compound in HPLC columns was simulated by FEMLAB. To study change of elution profile with isotherm models, non-competitive and competitive Langmuir adsorption isotherm were adopted. Separated material was (R, S)-ibuprofen [(R, S)-2-(4-isobutyl phenyl) propionic acid], an anti-inflammatory agent, which retain the pharmacological activity in the (S)-(+)-enantiomer. Sample concentrations were changed from 0.5 mg/ml to 2.0 mg/ml at a flow rate of 1 ml/min and flow rate varied from 1 ml/min to 3 ml/min at an ibuprofen concentration of 2.0 mg/ml and $20{\mu}l$ of injection volume. Simulated results were well fitted with experimental data.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.1-13
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• 2019

The accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) resulted in the deposition of large quantities of radionuclides over parts of eastern Japan. Radioactive contaminants have been observed over a large area including forests, cities, rivers and lakes. Due to the strong adsorption of radioactive cesium by soil particles, radioactive cesium migrates with the eroded soil, follows the surface flow paths, and is delivered downstream of population-rich regions and eventually to coastal areas. In this study, we developed a model to simulate the transport of contaminated sediment in a watershed hydrological system and this model was compared with observation data from eroded soil observation instruments located at the Korea Atomic Energy Research Institute. Two methods were applied to analyze the soil particle size distribution of the collected soil samples, including standardized sieve analysis and image analysis methods. Numerical models were developed to simulate the movement of soil along with actual rainfall considering initial saturation, rainfall infiltration, multilayer and rain splash. In the 2019 study, a numerical model will be used to add rainfall shield effect by trees, evaporation effect and shield effects of surface water. An eroded soil observation instrument has been installed near the Wolsong nuclear power plant since 2018 and observation data are being continuously collected. Based on these observations data, we will develop the numerical model to analyze long-term behavior of radionuclides on land as they move from land to rivers, lakes and coastal areas.