• Journal of Soil and Groundwater Environment
• /
• v.13 no.1
• /
• pp.32-42
• /
• 2008

A surfactant recovery and reuse process by selective adsorption with activated carbon was proposed to reduce surfactant cost in a soil washing process. Mathematical model simulation was performed for the whole process, which consists of soil washing, soil recovery, and soil re-washing. The optimal range of surfactant dosage was $6{\sim}10$-fold critical micelle concentration in soil. The efficiency of surfactant reuse process was decreased with increasing the dosage of activated carbon. Effectiveness factor for activated carbon significantly altered the efficiency of the reuse process unlike effectiveness factor for soil. Total requirement of surfactant was reduced to 20-30% with the reuse process compared to the conventional soil washing process. The contamination of wastewater after soil washing was reduced with the reuse process. This mathematical model can be used to estimate performance of the whole process of soil washing including surfactant recovery and to obtain optimal ranges of operating conditions without extra labor-intensive experimental works.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.2
• /
• pp.1-11
• /
• 2008

Phenanthrene uptake by surfactant sorbed on activated carbon was investigated to recycle of surfactant in washed solution for contaminated soil. The partitioning of phenanthrene to the activated carbon coating with Triton X-100 as a surfactant was also evaluated by a mathematical model. Phenanthrene-contaminated soil (200 mg/kg) was washed in 10 g/L of surfactant solution. Washed phenanthrene in solution was separated by various particle loadings of granular activated carbon through a mode of selective adsorption. Removal of phenanthrene was 99.3%, and surfactant recovery was 88.9% by 2.5 g/L of granular activated carbon, respectively. Phenanthrene uptake by activated carbon was greater than that of phenanthrene calculated by a standard model for a system with one partitioning component. This is accounted for enhanced surface solubilization by hemi-micelles adsorbed onto granular activated carbon. The effectiveness factor is greater than 1 and molar ratio of solubilization to sorbed surfactant is higher than that of liquid surfactant. Results suggest that separation of contaminants and surfactants by activated carbon through washing process in soil is much effective than that of calculated in a theoretical model.

• Economic and Environmental Geology
• /
• v.32 no.4
• /
• pp.385-398
• /
• 1999

The Narim gold mine is located approimately 200km southeast of Seoul within the Muju mineralized district of the Sobaegsan gneiss complex, Korea. Environmental geochemistry were undertaken for various kinds of water (surface, ground and mine water) collected of April, September and November in 1998 from the narim mine creek. Hydrogeochemical compositions of water samples are characterized by the relatively significant enrichment of Na+K, alkali ions, $HCO_{3}$, $NO_{3}$, Cl and F in groundwater, wheras the mine and surface waters are relatively enriched in Ca+Mg, hea표 metals and $SO_{4}$. Therefore, the groundwaters belong to the (Na+Ca)-( $HCO_{3}+SO_{4}$) type, respectively. The pH and EC values of the non-mining creek surfers are relatively lower compared with those of the surface water of the mine and ore dump area. The d values ($\delta$D-8$\delta^{18}$O) of all kinds of water from the Narim mine creek are 5.8 to 13.1 The range of $\delta$D and $\delta^{18}$O values (relative to SMOW) are shown in distinct two groups as follows: for the April waters of -64.8 to -67.8$\textperthousand$ and -9.6 to -10.0$\textperthousand$(d value=10.1 to 13.1), and for the November waters of -65.9 to -70.2$\textperthousand$ and -9.3 to -9.6$\textperthousand$ (d value=5.8 to 7.9), respectively. This range variation indicates that two group water were composed of distinct waters with seasonal difference. Geochemical modeling showed that mostly toxic metals (As, Fe, Mn, Ni, Pb, Zn) may exist largery in the from of metal $(M2^+)$ and metal-sulfate $(MSO_4\;^{2-$\mid$),\; and \;SO_4^{2-$\mid$}$ concentration influenced the speciation of heavy metals in the meteoric water. These metals in the groundwater could be formed of $CO_3 \;and \;(OH)_3$ complex ions. Using computer program, saturation index of albite, calcite, dolomite in meteoric water show undersaturated and progreddively evolved toward the saturation state, however, ground and mine water are nearly saturated. The gibbsited water-mineral reaction and stabilities suggest that the weathering of silicate minerals may be stable kaolinite, illite and Nasmectite. The clay minerals will be transformed to more stable kaolinite owing to the contiunous reaction.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.3
• /
• pp.133-145
• /
• 2010

This study analyzed the characteristics of sediment produce by landslide triggered by rainfall. One-dimensional unsaturated groundwater model and infinite slope stability analysis were used to estimate the behavior of soil moisture and slope stability according to rainfall, respectively. Slope stability analysis was performed considering on soil depth and characteristics of trees. As the results considering on recovery of the failed slopes, much amount of sediment was produced in 1963, 1970, and 2002. As the results of verification of simulation results using Landsat 5 TM images, we can find differences of landslide location between the results from model and satellite images. These differences can be caused by uncertainties of the rough parameters in the model. However, in the case that Obong-dam basin was divided into two subbasin, Wangsan-chun and Doma-chun basin, the results of each subbasin show errors around 20%. And only 4% of error occurred in the case of comparing landslide area on the entire Obong-dam basin. These errors seem insignificant considering on the errors which can be caused from the analyses in this study such as estimation of sediment produce, soil cover classification, and estimation of landslide area.

• Geophysics and Geophysical Exploration
• /
• v.11 no.2
• /
• pp.85-92
• /
• 2008

Magnetotelluric (MT) methods are widely applied as an effective exploration technique to geothermal surveys. Two-dimensional (2-D) analysis is frequently used to investigate a complicated subsurface structure in a geothermal region. A 2-D finite-element method (FEM) is usually applied to the MT analysis, but we must pay attention to the accuracy of so-called auxiliary fields. Rodi (1976) proposed an algorithm of improving the accuracy of auxiliary fields, and named it as the MOM method. Because it introduces zeros into the diagonal elements of coefficient matrix of the FEM total equation, a pivoting procedure applied to the symmetrical band matrix makes the numerical solution far less efficient. The MOM method was devised mainly for the inversion analysis, in which partial derivatives of both electric and magnetic fields with respect to model parameters are required. In the case of forward modeling, however, we do not have to resort to the MOM method; there is no need of modifying the coefficient matrix, and the auxiliary fields can be elicited from the regular FEM solution. The computational efficiency of the MOM method, however, can be greatly improved through a sophisticated rearrangement of the total equation.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.5
• /
• pp.18-28
• /
• 2009

Both feasibility and accuracy of lumped approach to group 12 organic compounds in mixtures into a fewer number of pseudocompounds in sorption processes were evaluated using mixtures containing organic compounds with various physicochemical properties and low-surface-area mineral sorbents. The lumped approach for sorption to simulated mineral sorbents was developed by cluster analysis from statistics. Using the lumped approach, the sorption estimated from both reduced number of pseudocompounds and their sorption parameters (i.e., $K_f$, n) can approximate sorption behavior of complex organic mixtures. Additionally, the pseudocompounds for various mixtures to different types of low-surface-area mineral sorbents can be estimated a priori from the physicochemical properties of organic compound (i.e., ${\gamma_w}^{sat}$). Therefore, the lumped approach may help to simplify the complex fate and transport model of organic contaminant mixtures, reduce experimental efforts, and yet provide results that are statistically identical for practical purposes. Further research is warranted to enhance the accuracy of lumped approach using the multiple regression analysis considering the H-bonding capacity, site concentrations, functional groups for mineral sorbents.

• Journal of Soil and Groundwater Environment
• /
• v.26 no.6
• /
• pp.106-117
• /
• 2021

The purpose of this study is prediction of landslide occurrence reflecting the subsurface flow characteristics within the soil layer in the future due to climate change in a large scale watershed. To do this, we considered the infinite slope stability theory to evaluate the landslide occurrence with predicted soil moisture content by SWAT model based on monitored data (rainfall-soil moisture-discharge). The correlation between the SWAT model and the monitoring data was performed using the coefficient of determination (R²) and the model's efficiency index (Nash and Sutcliffe model efficiency; NSE) and, an accuracy analysis of landslide prediction was performed using auROC (area under Receiver Operating Curve) analysis. In results comparing with the calculated discharge-soil moisture content by SWAT model vs. actual observation data, R² was 0.9 and NSE was 0.91 in discharge and, R² was 0.7 and NSE was 0.79 in soil moisture, respectively. As a result of performing infinite slope stability analysis in the area where landslides occurred in the past based on simulated data (SWAT analysis result of 0.7~0.8), AuROC showed 0.98, indicating that the suggested prediction method was resonable. Based on this, as a result of predicting the characteristics of landslide occurrence by 2050 using climate change scenario (RCP 8.5) data, it was calculated that four landslides could occur with a soil moisture content of more than 75% and rainfall over 250 mm/day during simulation. Although this study needs to be evaluated in various regions because of a case study, it was possible to determine the possibility of prediction through modeling of subsurface flow mechanism, one of the most important attributes in landslide occurrence.

• Tunnel and Underground Space
• /
• v.31 no.3
• /
• pp.167-183
• /
• 2021

It is essential to understand the complex thermo-hydro-mechanical-chemical (THMC) coupled behavior in the engineered barrier system and natural barrier system to secure the high-level radioactive waste repository's long-term safety. The heat from the high-level radioactive waste induces thermal pressurization and vaporization of groundwater in the repository system. Groundwater inflow affects the saturation variation in the engineered barrier system, and the saturation change influences the heat transfer and multi-phase flow characteristics in the buffer. Due to the complexity of the coupled behavior, a numerical simulation is a valuable tool to predict and evaluate the THMC interaction effect on the disposal system and safety assessment. To enhance the knowledge of THMC coupled interaction and validate modeling techniques in geological systems. DECOVALEX, an international cooperation project, was initiated in 1992, and KAERI has participated in the projects since 2008 in Korea. In this study, we introduced the main contents of all tasks in the DECOVALEX-2023, the current DECOVALEX phase, to the rock mechanics and geotechnical researchers in Korea.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.4
• /
• pp.523-531
• /
• 2011

Many of the wells which were constructed to use ground water resource are abandoned and not managed efficiently after its use. And a variety of heavy metals and organic compounds are released from the abandoned wells and this can cause ground water pollution. Therefore in this paper implemented to monitor locational information drill holes and underground water sensing information on real time basis using u-GIS environment to combined ubiquitous sensor node and GIS technology to improve these problems. In addition, this system suggests using system by UML 2.0 by analyzing variety requirement of user and between system internal modules interaction and data flow. It provides graphical user interfaces (GUI) to system users to monitor water-well related property information and its managements for each water-well at remote site by variety platform by GIS map and web environment and mobile device based on smart phone.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.10 no.1
• /
• pp.55-62
• /
• 2012

As an alternative of the high-level radioactive waste disposal in the subsurface repository, a deep borehole disposal is reviewed by several nuclear advanced countries. In this study, the state of the art on the borehole disposal researches was reviewed, and the possibility of borehole disposal in Korean peninsula was discussed. In the deep borehole disposal concept radioactive waste is disposed at the section of 3 - 5km depth in a deep borehole, and it has known that it has advantages in performance and cost due to the layered structure of deep groundwater and small surface disposal facility. The results show that it is necessary to acquisite data on deep geologic conditions of Korean peninsula, and to research the engineering barrier system, numerical modeling tools and disposal techniques for deep borehole disposal.