• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.15-18
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• 2001

Sorption/desorption studies were conducted to determine sorption/desorption characteristics of phenolic compounds (phenol and 4-chlorophenol) in organically modified natural bentonite. The cationic exchange capacity (CEC) of bentonite was exchanged with a cationic surfactant, hexadecyltrimethylammonium (HDTMA), to enhance the removal capacity of organic phenol contaminants dissolved in aqueous solution. This modification produces a change of the surface property of bentonite from hydrophilic to organophilic. The single-solute and bi-solute competitive adsorptions were performed In batch mode to investigate the removal of two toxic organic Phenols, chlorophenol and 4-chlorophenol on the HDTMA-bentonite. The adsorption affinity of the 4-chlorophenol was higher than phenol due to higher octanol:water partition coefficient (Kow). The single-solute and bi-solute competitive desorptions were also performed investigate the competitive desorption of the phenolic compounds from HDTMA-bentonite. Freundlich model was used to analyze the single-solute adsorption/desorption results, while the IAST model predicted the hi-solute adsorption/desorption equilibria. The IAST model well predicted hi-solute competitive adsorption/desorption behaviors.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.89-92
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• 2001

This study aims at investigating the relationship between dispersion coefficient ratio to molecular diffusion coefficient (D$_{l}$ /D$_{m}$) and Peclet number (Pe) for multi-solute system in non-Darcian flow regime. Existing understanding on solute dispersion is primarily derived from one-solute system in Darcian flow regime. We found that solute dispersion in rock fractures can be characterized by the mechanism of both macrodispersion and Taylor dispersion, even for non-Darcian f]ow domain. For the Darcian flow regime even different solutes lead to the same D$_{l}$ /D$_{m}$ at same Pe. However, as the flow becomes non-Darcian, solute with a higher molecular diffusion coefficient result in higher D$_{l}$ /D$_{m}$ at tile same Pe than that with a lower diffusion coefficient.cient.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.127-136
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• 2013

In this study, atomistic simulations are performed to study the effect of Al solute on the behaviour of edge dislocation in Mg alloys. After the dissociation of an Mg basal edge dislocation into two Shockley partials using molecular mechanics, the interaction between the dislocation and Al solute at different temperatures is studied using molecular dynamics. It appears from the simulations that the critical shear stress increases with the Al solute concentration. Comparing with the solute effect at T = 0 K, however, the critical shear stress at a finite temperature is lower since the kinetic energy of the atoms can help the dislocation conquer the energy barriers created by the Al atoms. The velocity of the edge dislocation decreases as the Al concentration increases when the external shear stress is relatively small regardless of temperature. The Al concentration effect on the dislocation velocity is not significant at very high shear stress level when the solute concentration is below 4.0 at%. Drag coefficient B increases with the Al concentration when the stress to temperature ratio is below 0.3 MPa/K, although the effect is more significant at low temperatures.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1997년도 총회 및 춘계 학술발표회 논문집
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• pp.25-29
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• 1997

In many solute transport studies, either flux or resident concentration has been used. Choice of the concentration mode was dependent on the monitoring device in solute displacement experiments. It would be questionable, however. to accept the equivalency in the solute transport parameters between flux and resident concentrations in structured soils exhibiting preferential movement of solute. In this study, we investigate how they differ in the monitored breakthrough curves (BTCs) and transport parameters for a given boundary and flow condition by performing solute displacement experiments on a number of undisturbed soil columns. Both flux and resident concentrations have been simultaneously obtained by monitoring the effluent and resistance of the Horizontally-positioned TDR probes. The study reveals that soil columns having relatively high flux densities exhibited great differences in the degree of peak concentration and travel time of peak between flux and resident concentrations. The peak concentration in flux mode was several times higher than that in resident one. This was mainly due to the bypassing of solute through soil macropores.

• Bulletin of the Korean Chemical Society
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• 제20권10호
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• pp.1209-1212
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• 1999

The entropies and chemical potentials of hard-sphere solutes solvated in hard-sphere solids were calculated by Monte Carlo method using the radial free-space distribution function. This method is based on calculating the entropy by comparing the free volume of a molecule with that of an ideal gas, and is applicable even when the size of solute is very large and the solvent is a solid. When the diameter of hard-sphere solute is small the solute molecule behaves as like as a fluid in solid structures, but when the diameter of solute becomes large, a fluid-to-solid phase transition takes place. The fluid-to-solid phase transition occurs at the region of the smaller size of solute with the more increase of solvent density. The least square fit values of analytical form of the radial free-space distribution functions of solute molecules are presented for future uses.

• 대한화학회지
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• 제34권4호
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• pp.377-383
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• 1990

용매 존재하에서 2-hydroxyethylmethacrylate와 acrylamide, N, N-dimethylamide 및 methylmethacrylate를 함량에 따라 3종류의 공중합체 수화겔막을 제조한 다음 이들 막에 알코올용질의 투과 및 분배계수를 측정하였으며, 이 측정값들을 이용하여 용질의 투과 메카니즘을 논의하였다. 수화겔막에서 유기용질의 투과계수는 그 분자의 크기에 주로 의존하였다. 그러나 수화겔막 내에 존재하는 물의 함량이 낮아지면 막에 대한 용질의 용해도가 점차 중요해짐을 또한 알 수 있었다. 분배계수의 측정 결과에 의하면 수화겔막에서의 용질의 분배는 주로 막과 용질사이에 존재하는 소수성 상호작용에 의해 조절되었다. 그리고 수화겔막에 유기용질의 확산은 전적으로 빈자리에 의존하며, 물분자와 용질 사이에 극성-편극성 및 수소결합도 부분적으로 영향을 미치나 그 정도가 아주 미약함을 확인하였다.

• 한국재료학회지
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• 제24권5호
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• pp.229-235
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• 2014

In this paper, the effects of precipitates and Mn-solute atoms on the recrystallization behavior of an Al-Mn alloy was studied using micro-Vickers hardness, electrical conductivity measurements and optical microscopy. Various thermo-mechanical processes were designed to investigate the different morphologies, and the solute concentration, of Mn in the matrix. The results indicate that the recrystallization temperature, $T_R$ and time, $t_R$, are influenced by the amount of M-solute atoms in the matrix, and that the recrystallization microstructure is influenced by the amount of precipitates. Recrystallization in the Slow-Cooling specimen was rapid due to its low concentration of Mn-solute atoms, and the crystal-grain size was the smallest due to finely distributed precipitates. However, in the case of the No-Holding specimen, elongated grains were observed at the low annealing temperature and the largest recrystallized grains were observed at the high annealing temperatures (compared with Slow-Cooling and Base specimens) due to the high Mn-solute atoms in the matrix.

• 한국막학회:학술대회논문집
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• 한국막학회 1996년도 추계 총회 및 학술발표회
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• pp.3-7
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• 1996

A rigorous analysis on the effect of colloidal interactions on the separation characteristic has been extended to the case of non-dilute charged solute concentration. The solute partitioning within slit pores for a wide range of solute concentration has been predicted by performing the Monte Carlo technique. Using a hindered transport model, rejection coefficients have been estimated from the predicted concentration profile.

• 멤브레인
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• 제28권4호
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• pp.286-295
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• 2018

폴리에틸렌이민(분자량 800)에 다가이온을 갖는 정삼투용 새로운 유도용질을 합성하고 특성을 분석하였다. 폴리에틸렌이민과 메틸 아크릴레이트의 중화반응으로 중간체를 합성하고, KOH로 가수분해하여 수용성의 카복실산 금속염 형태의 폴리에틸렌이민을 합성하였다. NMR, 점도, 삼투압을 측정하여 유도용질의 특성을 평가하였다. 그 염이 유도용질로서 사용할 수 있는지의 여부를 정삼투 실험을 통하여 알아보았다. 유도용질로서 수투과도와 역염 투과도를 측정하여 NaCl과 비교하였다. 정삼투와 나노여과의 혼성공정을 통하여 유도용질의 회수가능성을 보였다.

• 대한토목학회논문집
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• 제29권1B호
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• pp.73-81
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• 2009

본 연구에서는 개수로 흐름에서 오염물질 이동 현상에 대한 이차흐름의 영향을 분석하였다. 운동량 방정식과 스칼라 수송 방정식에서의 난류 폐합을 위해 레이놀즈응력 모형 및 GGDH 모형을 사용하였다. 개발된 모형을 이용하여 조 세립상의 횡방향 연속구조를 갖는 개수로 흐름에서의 오염물질 이동에 대한 이차흐름의 영향을 분석하였다. 그 결과, 이차흐름의 영향으로 인해 최대 농도 값의 발생 위치가 이동하는 것으로 나타났으며, 농도 분포 역시 정규 분포에서 거리에 따라 점차 왜곡 되는 것으로 확인되었다. 또한, 이차흐름의 영향으로 자유수면 근처에서는 매끄러운 하상에 비해 거친 하상에서의 오염물질 농도가 더 크게 발생되었으며, 스칼라-흐름률을 계산한 결과, 오염물질의 수직방향 확산은 매끄러운 하상에 비해 거친 하상에서 더 빨리 진행되는 것으로 확인되었다. 한편, 농도 분포 변화에 대한 이차흐름 및 스칼라-흐름률의 영향을 살펴보기 위하여 스칼라 수송률 분석을 수행하였다.