• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.836-841
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• 2008

CFRD (Concrete Faced Rockfill Dam) has been world-widely constructed due to a lot of advantages compared with rockfill dam and recently, sand/gravel materials, instead of crushed rock materials, are also utilized as a main rockfill material to overcome geological and environmental problems. In this paper, the process of water infiltration into the originally unsaturated sand/gravel-fill dam is studied using two-dimensional saturated-unsaturated seepage theory. According to the results of seepage analysis, if the effective drainage zone is installed in the dam, the reservoir water infiltrate into the dam along a downward flow path towards the lower drainage area. The main body constructed with sand/gravel materials, therefore, remains unsaturated.

• Advances in environmental research
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• v.5 no.4
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• pp.263-282
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• 2016

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

• Journal of the Speleological Society of Korea
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• v.46 no.47
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• pp.9-18
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• 1996

우리나라에는 수 많은 석회동굴이 있다. 현재까지 파악된 것만 해도 총 1,000 여개 소에 달하는 것으로 추정되고 있으나 실제로는 이보다 많은 동굴이 있을 것이다. 이들 석회동굴의 용식미형태는 다양하다. 따라서 본 연구에서는 포화수대에서 형성된 동굴 속의 용식작용으로 이루어진 동굴 미지형, 동굴 지물들에 대하여 논하고저 한다. 순환수대에서의 동굴 생성물과 미지형은 단조롭고 뚜렷하다고 하겠지만, 이와 반대로 포화수대 동굴 속의 미지형들은 그 모두가 용식작용으로만 이루어지는 것이다. 이들 미지형은 계속 순환수대 동굴로의 이행 때문에 침식ㆍ삭박작용도 가해지는 경우가 있어 이른바 복합적인 미지형이 남게 되는 것이다. 현재 우리나라에는 수 많은 석회동굴이 있으나 개발되어 공개되고 있는 동굴 중에서는 단양의 고수동굴과 동해시의 천곡동굴에서 이와 같은 용식미지형을 볼 수 있다. 앞으로 이들에 대한 보다 계측적이고 구체적인 학술적 연구가 기대되는 바이다.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.33-36
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• 2007

In recent years the convective-dispersive equation has been often discredited in predicting subsurface solute transport under field conditions due to presence of preferential flow paths. Kim et al. (2005) proposed a simple equation that can predict the breakthrough of solutes without excessive data requirements. In their Generalized Preferential Flow Model (GPFM), the soil is conceptually divided in a saturated "distribution layer" near the surface and a "conveyance zone" with preferential flow paths below. In this study, we test the model with previously published data, and compare it with a classical convective-dispersive model (CDM). With three parameters required-apparent water content of the distribution zone, and solute velocity and dispersion in the conveyance zone-GPFM was able to describe the breakthrough of solutes both through silty and sandy loam soils. Although both GPFM and CDM fitted the data well in visual, variables for GPFM were more realistic. The most sensitive parameter was the apparent water content, indicating that it is the determining factor to apply GPFM to various soil types, while Kim et al. (2005) reported that changing the velocity of GPFM reproduced solute transport when same soils were used. Overall, it seems that the GPFM has a great potential to predict solute leaching under field conditions with a wide range of generality.

• Journal of the Korean GEO-environmental Society
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• v.16 no.8
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• pp.21-35
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• 2015

Electrical resistivity survey (2D and 3D) were employed for detection of possible weak zone of core zones of three central core earth-rockfill dams in Korea. In the 2D results, the core zones is lower resistivity zone with less than $50{\sim}400ohm{\cdot}m$, and the basement is relatively higher resistivity zone with over $1,000ohm{\cdot}m$. In the 3D results, especially, the weak zone with under $100ohm{\cdot}m$ was detected spatial distribution area in the dam. We also drilled boreholes to collect soil samples of core zones of each dam. Water was not used during boring, because water for rotary wash boring could cause structural damages in earth dams. We found that the soil samples of core zones from all of the boreholes correspond to CL (USCS), but we also found that the fluidized or water-saturated soil samples were found in lower resistivity zones. Therefore, the electrical resistivity survey and drilling method without water are a quick and efficient method for structural-health evaluation which is detection of possible weak zones in earth core rockfill dams.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.191-206
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• 2007

The general theoretical solutions for the wavespeed and damping derived in Part 1 of this work, are incorporated into the computer code. In this paper the code is used in a parametric study of the influence of excitation frequency and variations in material properties on propagation velocity and damping. Compressional wave velocity for waves of the first kind is shown to vary as a function of the frequency-permeability product, with a zone where wavespeed transitions from a lower bound value to a higher bound value with increasing values of the product. Damping is seen to be a maximum where the rate of change in wavespeed is greatest. Waves of the second kind also show a transition in wavespeed from near zero at low values of the frequency-permeability product to an upper bound value at higher values of the product.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.590-598
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• 2006

In-situ Air sparging (IAS) is a groundwater remediation technique, in which organic contaminants volatilize into air form the saturated to vadose zone. This study was carried out to evaluate the effect of sludge and soil microbial community structure on air sparging of Total Petroleum Hydrocarbons (TPH) contaminated groundwater soils. In the laboratory, diesel (10,000 mg TPH/kg) contaminated saturated soil. The Air was injected in intermittent (Q=1500 mL/min, 10 minute injection and 10 minute idle) modes. For Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis of eubacterial communities in sludge of wastewater treatment plants and soil of experiment site, the 16S rDNA was amplified by Polymerase Chain Reaction (PCR) from the sludge and the soil. The obtained 16S rDNA fragments were digested with Msp I and separated by electrophoresis gel. We found various sequence types for experiment with sludge soil samples that were closely related to Agrococcus, Flavobacterium, Thermoanaerobacter, Flexibacter and Shewanella, etc, in the clone library. The results of the present study suggests that T-RFLP method may be applied as a useful tool for the monitoring in the TPH contaminated soil the fate of microorganisms in natural microbial community.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.19-29
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• 2008

Hot air sparging is a groundwater remediation technique, in which organic contaminants volatilized into hot air from the saturated to vadose zone. In the laboratory diesel (10,000 mg TPH/kg) was spiked in contaminated saturated aquifer soil. The hot air ($34.9{\pm}2.7^{\circ}C$) was injected in intermittent (Q=1,500 mL/min, 10 minute injection and 10 minute idle) modes. We performed microcosm tests using the groundwater samples to assess TPH reductive remediation activity. For Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis of eubacterial communities in sludge of wastewater treatment plants and soil of experiment site, the 16S rDNA was amplified by Polymerase Chain Reaction (PCR) from the sludge and the soil. The obtained 16S rDNA fragments were digested with Msp I and separated by electrophoresis gel. We found various sequence types for hot air sparging experiment with sludge soil samples that were closely related to Bacillus (149 bp, Firmicutes), Methlobacterium (149 bp, Euryarchaeotes), Pseudomonas (492 bp, ${\gamma}$-Proteobacteria), etc., in the clone library. In this study we find that TPH-water was reduced to 78.9% of the initial value in this experiment aquifer. The results of the present study suggests that T-RFLP method may be applied as a useful tool for the monitoring in the TPH contaminated soil fate of microorganisms in natural microbial community.

• Journal of Korea Water Resources Association
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• v.37 no.2
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• pp.97-108
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• 2004

Recently the ground-water development using the ground-water dam was proposed for the efficient use of the limited water resources especially for islands or seaside area. But in operating the ground-water dam adjacent to seaside an excessive pumping causes the sea-water intrusion which is caused by the drawdown of ground-water level. In this study, the effect of the recharging well method to reduce the sea-water intrusion was evaluated, and was applied to the downstream of the Ssangcheon ground-water dam site. The SUTRA model was used to simulate the salinity transport in the unsaturated and saturated zone. As the results, the effect of recharging method on the downstream of the ground-water dam was proven to be very efficient to reduce the salinity in the pumping well, and especially the best result was shown at the case that the recharging well is located at 40∼60m from the cutoff wall and the recharging rate is up to 6∼7％.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.423-431
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• 2008

In general, water-saturated silt or clay alluvium is characterized with relatively low-resistivity. Thus we often encountered the problem that such a low-resistivity layer is misguided to be good aquifer of high-permeability and low-resistivity in the development of groundwater. This research was conducted with an emphasis on the identification of saturated silt or clay layer from the aquifer by performing the laboratory experiment of IP and resistivity methods on the various materials consisting of alluvium aquifer. Silt or clay layer is found to be characterized with the higher chargeability zone, compared to the sand layer. Regarding the mixture of sand and clay, the higher clay volume, the lower resistivity and the higher chargeability. Subsequently chargeability decreases.