• Journal of Soil and Groundwater Environment
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• v.20 no.2
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• pp.41-46
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• 2015

The drag of the excess charge in an electrical double layer at the solid fluid interface due to water flow induces the streaming current, i.e., the streaming potential (SP). Here we introduce a sandbox experiment to study this hydroelectric coupling in case of a tracer test. An acrylic tank was filled up with homogeneous sand as a sand aquifer, and the upstream and downstream reservoirs were connected to the sand aquifer to control the hydraulic gradient. Under a steady-state water flow condition, a tracer test was performed in the sandbox with the help of peristaltic pump, and tracer samples were collected from the same interval of five screened wells in the sandbox. During the tracer test, SP signals resulting from the distribution of 20 nonpolarizable electrodes were measured at the top of the tank by a multichannel meter. The results showed that there were changes in the observed SP after injection of tracer, which indicated that the SP was likely to be related to the solute transport.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.169-177
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• 1994

Dilute Al-Cu and Al-Mg alloys were solidified unidirectionally upward by Bridgman method. It is necessary that solute concentration of initial melt is uniform to be able to control the concentration of crystal. When solute concentration is not uniform, it can cause unusual macro-segregation in grown solid. A non-steady state solidification was observed where the solute concentration in the grown solid decreased with the progress of solidification, when a dilute Al-Cu melt with positive axial temeprature gradient was solidified. This was caused by leaking out of Cu-rich melt into the gap between ingot and crucible during melt-down and its sedimentation after complete melting. In the case of Al-Mg alloy, the solute concentration has a minimum in the middle of grown specimen because Mg-rich melt flowed down the gap between ingot and crucible and floated after complete melting. Uniform initial melt concentration can be achieved by the homogenization of the ingot or by the absence of the gap between ingot and crucible.

• Economic and Environmental Geology
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• v.29 no.6
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• pp.699-712
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• 1996

Field scale experiments using an automated 144-channel TDR system were conducted which monitored the movement of solute through unsaturated loamy soils. The experiments were carried out on two different field plots of 0.54 ha to study the vertical movement of solute plume created by applying a square pulse of $CaCl_2$ as a tracer. The residence concentration was monitored at 24 locations on a transect and 5 depths per location by horizontally-positioning 50 cm long triple wire TDR probes to study the heterogeneity of solute travel times and the governing transport concept at field scale. This paper describes details of experimental methodology and calibration aspects of the TDR system. Three different calibration methods for estimation of solute concentration from TDR-measured bulk soil electrical conductivity were used for each field site. Data analysis of mean breakthrough curves (BTCs) and parameters estimated using the convection-dispersion model (CDE) and the convective-lognormal transfer function model (CLT) reveals that the automated TDR system is a viable technique to study the field scale solute transport providing a normal distribution of resident concentration in a high resolution of time series, and that calibration method does not significantly affect both the shape of BTC and the parameters related to the peak travel time. Among the calibration methods, the simple linear model (SLM), a modified version of Rhoades' model, appears to be promising in the calibration of horizontally-positioned TDR probes at field condition.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.234-239
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• 1998

Unidirectional solidification of $Al-CuAl_2$ eutectic composites was studied under the condition of forced convection by vibration. It has been shown that thermal gradient for solid is different from that for liquid during solidification under force convection by vibration. With increase of vibration, mobility of liquid increases, but decreases with decreasing vibration. The rate of solidification is very high initially, and decreases suddenly. For further solidification, the rate of solidification decrceases slowly, and shows a L-type behavior. The mechanical vibration during solidification effects efficiently on nucleation, and induces a forced convection in liquid. By the forced convection, great thermal gradient of liquid interface between solid and liquid can be obtained. The amount of solute near the interface also decreases as solute distribution is improved by the forced convection.

• Water for future
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• v.23 no.2
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• pp.213-225
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• 1990

A mathematical model is presented for predicting the steady state two-demensional distribution of solute concentration in the meandering nonuniform natural channel. The dispersion equation derived herein employs the transverse cumulative discharge as an independent variable replacing the transverse distance and that it is developed in an orthogonal curvilinear coordinnate system which follows the flow direction of natural channel. The prediction from the results of numerical model are compared with laboratory experiment data. It is found that results from simulation and experiments are in good agreement.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1512-1517
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• 2008

Laboratory column tests were conducted in this study using $Cl^-$ tracers on Jumunjin sand to analyze contaminant transport in mixed contaminated soils. Results obtained from clean soils and soils containing residual diesel verified heterogeneous distribution of residual diesel, and clear acceleration of solute movement. In addition, asymmetric breakthrough curves indicated development of immobile region where solute movement becomes stagnant and creates tailing phenomenon.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.56-62
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• 1992

The GaAs bulk crystals are grown by the Synthesis Solute Diffusion(SSD) method and its properties are investigated. The crystal growth rate at optimum condition is 0.28 cm/day and their temperature dependence is R(T) = 2.92 x 10S04T exp(-1.548eV/kS1BTT) [cmS02T/day.K]. Etch pits density distribution along radial direction is order of 10S04TcmS0-2T and 10S03TcmS0-2T at the edge and middle of the wafers, respectively, and it increased exponentially along vertical direction of ingot. Moreover,it is uniformly distributed as order of 10S03TcmS0-2T in radial direction of In doped GaAs. The carrier concentration and mobilities are measured to 0.34-2.1 x 10S016T cmS0-3T and 2.3-3.3x10S03T cmS02T/V.sec, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.316-319
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• 2005

Contaminated area should be identified for designing polluted groundwater cleanup plan. A methodology was suggested to identify a contaminant plume distribution geostatistically. James & Gorelick (1994) suggested a methodology to evaluate data worth as expected reducing remediation cost. In this study, their methodology was modified to evaluate data worth as expected reducing uncertainty of the contaminant plume distribution. In suggested methodology, the source identification model by Mahar & Datta (2001) using a forward solute transport model is integrated. Suggested methodology was assessed by two simple example problems and its result represented reducing uncertainties of contaminant plume distribution successfully.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.656-662
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• 1999

We have obtained retention data of benzene, toluene, ethylbenzene, phenol, and acetophenone at 25, 30, 35, 40, 45 and 50 $^{\circ}C$ in 30/70, 40/60, 50/50, 60/40, 70/30, and 80/20 (v/v %) methanol/water eluents using a $C_18$ phase with a high ligand density. We drew van't Hoff plots from the data, and computed enthalpies and entropies of solute transfer from the mobile to the stationary phase. The cavity formation effect was found the major factor that governs the solute distribution between the mobile and stationary phases. The hydrophobic effect became significant in highly aqueous mobile phases. We also concluded that the Shodex C18-5B stationary phase was a polymer-like phase with a high ligand density, and followed a partially adsorption-like mechanism.

• Bulletin of the Korean Chemical Society
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• v.1 no.4
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• pp.138-143
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• 1980

Hydrogel membranes were prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidone (VP) in the presence of the solvent and the crosslinker tetraethyleneglycol dimethacrylate (TEGDMA). By changing the monomer composition and the crosslinker content, different membranes were synthesized. Using these membranes, relative permeabilities and distribution coefficients for amides including urea were measured. The water contents in membrane were also measured. On the basis of solute-membrane matrix interaction, the results were interpreted.