• Membrane and Water Treatment
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• v.2 no.4
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• pp.239-250
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• 2011

A photovoltaic powered ultrafiltration and reverse osmosis system was tested with a number of natural groundwaters in Australia. The objective of this study was to compare system performance at six remote field locations by assessing the impact of water composition and fluctuating energy on inorganic contaminant removal using a BW30-4040 membrane. Solar irradiance directly affected pressure and flow. Groundwater characteristics (including TDS, salts, heavy metals, and pH), impacted other performance parameters such as retention, specific energy consumption and flux. During continual system operation, retention of ions such as $Ca^{2+}$ and $Mg^{2+}$ was high (> 95%) with each groundwater which can be attributed to steric exclusion. The retention of smaller ions such as $NO_3{^-}$ was affected by weather conditions and groundwater composition, as convection/diffusion dominate retention. When solar irradiance was insufficient or fluctuations too great for system operation, performance deteriorated and retention dropped significantly (< 30% at Ti Tree). Groundwater pH affected flux and retention of smaller ions ($NO_3{^-}$ and $F^-$) because charge repulsion increases with pH. The results highlight variations in system performance (ion retention, flux, specific energy consumption) with real solar irradiance, groundwater composition, and pH conditions.

• Journal of Soil and Groundwater Environment
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• v.24 no.1
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• pp.10-16
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• 2019

Alkalinity is an essential parameter for understanding geochemical processes and calculating partial pressure of $CO_2$, dissolved inorganic carbon, and mineral saturation indices. The Gran Titration Method (GTM) is one of the most accurate methods for measuring the alkalinity in water samples. However, this method has not been widely employed in measuring groundwater alkalinity in Korea, probably due to inadequate and insufficient understanding of the method. In this regard, this article was prepared to introduce GTM and related know-hows learned from the authors' experiences in measuring alkalinity. This paper also introduces a MS Excel-based alkalinity calculator as a handy tool for GTM.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.415-424
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• 2004

This paper presents the effect of groundwater on tunneling performance. The interaction between the tunneling and groundwater was examined using a 3D stress-pore pressure coupled finite-element analysis, The results of the 3D coupled analysis were then compared with those of a total stress analysis. Examined items included pore pressures around lining and lining forces. Also examined include face displacements and ground surface movements, The results indicated that the interaction between the tunneling and ground water significantly increases the lining forces and ground deformations, and that the effect of ground water on tunneling can only be captured through a fully coupled analysis, Implementations of the findings from this study arc discussed in great detail.

• Geotechnical Engineering
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• v.8 no.4
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• pp.41-50
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• 1992

In general, the conceptual lumped-parameter groundwater flow model to predict the groundwater fluctuations in hillside slopes has unknown model parameters to be estimated from the known input -output data. The purpose of this study is to estimate the optimal model parameters of the groundwater flow model developed by authors. The Mazilnum A Posteriori( MAP) estimation method is utilized for this purpose and it is applied to a site which shows the typical landslide in Korea. The result of application shows tllat the 반AP estimation method can estimate the unknown parameters properly well. The groundwater model developed along with estimation technique applied in this paper will be used for assessing risk of landslides.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.5-16
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• 2016

This study aims to assess the influence of rainfall patterns on shallow landslides initiation. Doing so, five typical rainfall patterns with the same cumulative amount and intensity components comprising Advanced (A1 and A2), Centralized (C), and Delayed (D1 and D2) were designed based on a historical rainstorm event in Jinbu. Mt area. Those patterns were incorporated as the hydrological conditions into the Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) to assess their influences on groundwater pressure and changes in the stability of the slope. The results revealed that not only the cumulative rainfall thresholds necessary to initiate landslides, but also the rate at which the factor of safety decreases and the time required to reach the critical state, are governed by rainfall patterns. The sooner the peak rainfall intensity, the smaller the cumulative rainfall threshold, and the shorter the time until landslide occurrence. Left-skewed patterns were found to have a greater effect on landslide initiation. Specifically, among five rainfalls, pattern (A1) produced the most critical state. The severity of response was followed by patterns A2, C, D1, and D2. Our conclusion is that rainfall patterns have a significant effect on the cumulative rainfall threshold, the build-up of groundwater pressure, and the occurrence of shallow landslides.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.1-6
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• 2015

The objectives of this study were to calculate the radius of influence (ROI) of well for an air-sparging (AS)/soil vapor extraction (SVE) system and to evaluate the applicability of the system applied for the remediation of the petroleum contaminated rail site. For air permeability test, three monitoring wells were installed at a location of 1.3 m, 2.3 m, 3.0 m from the extraction well. And the pressure of each monitoring well was measured by extracting air from the extraction well with the pressure and flow of $(-)2,600mmH_2O$ and $1.58m^3/min$. The ROI for an extraction well was calculated as 4.31 m. Air was injected into the injection well with the pressure and flow of $3,500mmH_2O$ and $0.6m^3/min$ to estimate the radius of influence for oxygen transfer. Oxygen concentrations of air from three monitoring wells were measured. The ROI of an injection well for oxygen transfer was calculated as 3.46 m. The 28 extraction wells and 19 injection wells were installed according to the ROI calculated. The AS/SVE system was operated eight hours a day for five months. The rail site was contaminated with the petroleum and concentrations of benzene, toluene, and xylene were over the 'Worrisome Standard' of the 'Soil Environment Conservation Act'. The contaminated area was estimated as $732m^2$ and contaminants were dispersed up to (-)3 m from the ground. During the operation period, soil samples were collected from 5 points and analyzed periodically. With the AS/SVE system operation, concentrations of benzene, toluene, and xylene were decreased from 7.5 mg/kg to 2.0 mg/kg, from 32.0 mg/kg to 23.0 mg/kg, from 35.5 mg/kg to 23.0 mg/kg, respectively. The combined AS/SVE system applied to the rail site contaminated with volatile organic compounds (VOCs) exhibited a high applicability. But the concentration of contaminants in soil were fluctuated due to the heterogeneous of soil condition. Also the effect of the remediation mechanisms was not clearly identified.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.1-8
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• 2015

Deep geological disposal is the preferred storage method for high-level radioactive waste, because it ensures stable long-term storage with minimal potential for human disruption. Because of the risk of groundwater contamination, a buffer of steel and bentonite layers has been proposed to prevent the leaching of radionuclides into groundwater. Quartz is one of the most common minerals in earth's crust. To understand how deformation and dissolution phenomena affect waste disposal, here we study quartz samples at pressure, temperature, and pH conditions typical of deep geological disposal sites. We perform a dissolution experiment for single quartz crystals under different pressure and temperature conditions. Solution samples are collected and the dissolution rate is calculated by analyzing Si concentrations in a solution excited by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). After completing the dissolution experiment, deformation of the quartz sample surfaces is investigated with a confocal laser scanning microscope (CLSM). An empirical formula is introduced that describes the relationship between dissolution rate, pressure, and temperature. These results suggest that bentonite layers in engineering barrier systems may be vulnerable to thermal deformation, even when exposed to higher temperatures on relatively short timescales.

• Journal of Soil and Groundwater Environment
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• v.16 no.3
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• pp.10-16
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• 2011

The experimental studies for remediation of diesel contaminated soils were performed using subcritical water in laboratory scale. Contaminated soils from industrial area and artificially contaminated soils were utilized for soil remediation. Experimental system was composed for subcritical water to flow upward through the soil packed column for extracting contaminants. 10 g of contaminated soil was packed into the column and water flow rate was 2 mL/min. To evaluate the effects of temperature, pressure and treatment time on the removal efficiency, temperature was changed from 100$^{\circ}C$ to 350$^{\circ}C$, pressure from 50 bar to 220 bar and treatment time at the predetermined temperature from 0 min to 120 min. The purification efficiency increased as temperature increased. However, the effect of pressure and treatment time was low. Temperature 250$^{\circ}C$, pressure 50 bar and treatment time 30 min were selected for optimal operating condition for this study.

• Journal of Soil and Groundwater Environment
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• v.29 no.1
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• pp.1-9
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• 2024

As part of monitoring technology aimed at verifying the stability of CO₂ geologic storage and mitigating concerns about leakage, a method for measuring the pH and alkalinity of high-pressure fluid samples was established to obtain practical technology. pH measurement for high-pressure samples utilized a high-pressure pH electrode, and alkalinity was measured using the Gran titration method for samples collected with a piston cylinder sampler (PCS). Experimental samples, referencing CO₂-rich water and CO₂ geologic storage studies, were prepared in the laboratory. The PCS controls the piston, preventing CO₂ degassing and maintaining fluid pressure, allowing mixing with KOH to fix dissolved CO₂. Results showed a 6.1% average error in high-pressure pH measurement. PCS use for sample collection maintained pressure, preventing CO₂ degassing. However, PCS-collected sample alkalinity measurements had larger errors than non-PCS measurements, limiting PCS practicality in monitoring field settings. Nevertheless, PCS could find utility in preprocessing for carbon isotope analysis and other applications. This research not only contributes to the field of CCS monitoring but also suggests potential applications in studies related to natural analogs of CCS, CO₂-rock interaction experiments, core flooding experiments, and beyond.

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.101-113
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• 2012

The degradation of a tunnel drainage system leads to increases in pore water pressure around the tunnel and the lining stress, which results in affecting the tunnel stability. In the present study of the Namsan 3th tunnel, more than 30 year old tunnel, the effects of the drainage performance reduction due to drain hole clogging on the tunnel lining stability were investigated by examining pore water pressure distribution around the tunnel and the lining stresses through numerical analysis. Groundwater flow modeling on the Mt. Namsan region was done first and 3D seepage and coupled stress-pore water pressure finite element analysis were performed on the tunnel using the results of the groundwater flow modeling. The pore water pressure distribution and the tunnel lining stresses could be predicted using a drain hole outflow data measured in the tunnel site. This analysis method may be used to evaluate the current stability of old tunnels for which in most cases field investigations and related information are not readily available.