• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.29-35
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• 1999

Soil structure and organic matter have been known to strongly affect water flow and solute transport, yet little information is available concerning soil hydraulic properties related to soil physical and chemical properties in the forest site. The purpose of this study was to quantify the spatial variability and spatial correlation of the measured parameter values from the plots established with the rainfall simulator on Japanese larch(Larix leptolepis) dominated site in Kwangju. Kyunggi-Do. Measurement of soil water flux and retention were made with the inherent soil texture, soil structure, and organic matter. The method was based on the observation that when water was applied at a constant rate to the soil surface on each plot. The method was simple to apply and consists of following steps: (i) Wet the soil from a rainfall simulator with several known discharge rates on a relatively leveled soil surface with and without organic matter. (ii) Once the borders of the ponded zone were steady, saturated hydraulic conductivity( $K_{s}$) and the matric flux function(F) was evaluated from a regression of flux vs. the reciprocal of the ponded area. A conductivity of the form $K_{i+}$$_1$ $_{c}$= $K_{i}$( $_{c}$) [1-d /dz] where flux continuity implies. For this, continuity of matric potential at the interface at all times are as follows: $_1$( $Z_{c}$) = $_2$( $Z_{c}$) = $_{c}$ for steady state intake from water ponded on the soil surface. Results of this investigation showed the importance of understanding spatial variability in wide differences of water retention and saturated hydraulic conductivity with respect to pore geometry and organic matter contents which influenced the water flux throughout the soil profile.l profile.ile.

• Tunnel and Underground Space
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• v.27 no.3
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• pp.146-160
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• 2017

$CO_2$ sequestration for alleviating global warming is a hot issue in the world. In this study, TOUGH2 and FLAC3D were combined for analyzing the hyro-mechanical coupling behaviors expected in $CO_2$ sequestration and applied it to Sleipner project carried out in Norway. In the analysis, the influence of pore pressure on in situ stress was considered and the influence of caprock permeability on hydro-mechanical behaviors was analyzed. In the condition of constant injection rate, pressure and saturation at the injection well, liquid and gas saturation in rock, major and minor stress variations with time and distance from the injection well, and horizontal and vertical displacements after injection could be investigated. The major principal stress was quickly increased in the early stage and then slowly decreased to a stable value, which was higher than the initial value. In contrast, the minor principal stress returned to initial value after some increase in the early stage. Surface upheaval was steadily increased and it was up to 15mm in 2 years after injection. When the caprock's permeability was changed from $3e-15m^2{\sim}3e-18m^2$, it was found that the injection well pressure and surface upheaval were inversely propotional to the permeability.

• Journal of Korea Water Resources Association
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• v.52 no.1
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• pp.35-49
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• 2019

This study proposes a new method for categorizing the hydrological soil groups by considering the recent revision results of soil series. Also, the proposed method is evaluated by comparing the categorizing result with those based on existing three different methods. As an example, the proposed method is applied to Jeju Island to estimate the CN value, which is then compared with CN values estimated by applying the existing three different methods. Summaries of the results are as follow. (1) The revision result since 2007 shows that the soil texture has been changed in the 43 soil series, the drainage class in the 1 soil series, the permeability in the 15 soil series, and the impermeable layer in the 26 soil series. (2) The categorizing result of hydrological soil groups by applying the proposed method shows that the group B is the most dominant group covering up to 49.25%. On the other hand, one of the existing method of 1987 provides the group C as the most dominant group (46.43%). Method of 1995 defines the group B as the most dominant group (27.69%). The other method of 2007 distinguishes the group D (35.82%) to be the most dominant group. (3) Also, the CN value estimated by applying the proposed method to Jeju Island is found to be smaller than those based on existing three methods. This result indicates the possible overestimation of the CN value when applying the existing three methods.

• Korean Journal of Soil Science and Fertilizer
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• v.13 no.1
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• pp.1-6
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• 1980

The infiltration rates of the upland soils on hill side slope were investigated in situ using rainulator of which rainfall intensity was 100mm/hr. The soil moisture profile after the water infiltration was compared with that calculated from Youngs' equation. The results obtained are as follows: 1. Time required for infiltration rate to reach constant during rainfall was 15 to 25 min. The infiltration rate measured after 30 min was considered to be final infiltration rate. 2. The final infiltration rates of clay soils were lower than 10mm/hr., loamy soils 10 to 20., coarse loamy soils 20 to 30, and sandy soils higher than 30mm/hr., respectively. 3. The saturated hydraulic conductivity of the surface soil of Samgag sandy loam was 0.47mm/min., Songjeong clay loam0.16 mm/min., and Jeonnam silty clay loam 0.14mn/min., respectively. 4. The soil moisture profile calculated from Young's equation was in close agreement with measured in situ.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.59-64
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• 2013

Effects of weathering intensity on the adsorption of heavy metals such as lead(Pb) and copper(Cu) onto decomposed granite soils were investigated by a series of batch tests. The chemical components such as $SiO_2$, $K_2O$ and $Na_2O$ having relatively high solubility were reduced and the oxidized $Fe_2O_3$ content was increased with the increase of weathering intensity. Weathering of granite soils increased the ignition loss and specific surface area, while it decreased the permeability. The lead and copper adsorptions onto the decomposed granites were enhanced with the increase of weathering intensity, mainly due to the increase of specific surface area and clayed contents. Adsorption of lead and copper onto the weathered granites could be more adequately described by the pseudo-second-order kinetic model than the pseudo-first-order model.

• Geotechnical Engineering
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• v.14 no.4
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• pp.47-60
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• 1998

A series of conventional tests and CRS consolidation tests with different rates of strain were performed to investigate the consolidation characteristics of marine clay. Preconsolidation pressures were evaluated by applying previously proposed methods for both the conventional tests and CRS tests results in order to check the legitimacy of those methods. The effects of strain rate on effective consolidation stress strain relationship, porewater pressure, and preconsolidation pressure were also discussed It was found that the effective stress strain relationship and the preconsolidation pressure are a function of strain rate imposed during consolidation test, but compression index isn't. The preconsolidation pressure ratio ($a_2=\sigma'_{pCRS}/\sigma'_{pConv}$)of marine clay appears proportional to the logarithm of strain rate, with average values ranging from 1.11 to 1.30 for strain rates between $1\timesx10^{-4} %/sec\; and\; 4\times10 %/sec$. The porewater pressure ratio during CRS teats does not exceed 6.0% except when the strain rate is $6.67\times10^{-4} %/sec$. Coefficient of consolidation or coefficient of permeability at normally consolidated range was not affected by the type of consolidation tests and the strain rate. Typical values of compression index (C.), coefficient of consolidation(c.), and coefficient of permeability (k.) at normally consolidated range were 0.56-0.95, $0.56\times10^{-4}~3.0\times10^{-4}cm2/sec,\; and\; 2.0\times10^{-8}~7.0\time10^{-4}cm/sec,$ respectively.

• Journal of the Korean GEO-environmental Society
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• v.8 no.5
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• pp.31-38
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• 2007

The practical design method on sandmat uses a drain length, rate of consolidation settlement and permeability of sand as a major design factors. And, on the basis of this design process, it has been installed beneath the embankment with same thickness. However, the possibility the underestimation on the thickness of sandmat and the delayed drain have been pointed out by several authors caused by a differential settlement at the center and the end of embankment. In this study, therefore, the effect of the differential settlement on the thickness of sandmat and delayed drain through the numerical analysis of embankment was analyzed. As a result, a substantial sandmat thickness becomes small and the possibility of the delayed drain can be certified because of the development of differential settlement at the center and ends of embankment. As a countermeasure to overcome this problem, the applicability of the mound type sandmat was also investigated by the numerical method. It can be concluded that it maintains the designated substantial sandmat thickness throughout consolidation process, and is useful method to maintain the drain capacity. Especially, the mound type sandmat is effective method for a construction site where can cause a differential settlement such as embankment. Furthermore, it has to be designed on the basis of the accurate prediction of consolidation settlement as well as rate of consolidation settlement, drain length and permeability of sand.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.39-46
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• 2008

Due to the growth in industrialization, potential hazards in subsurface environments are becoming increasingly significant. The extraction of the contaminant from the soil and movement of the water are restricted due to the low permeability and adsorption characteristics of the reclaimed soils. There are a number of approaches to in-situ remediation that are used in contaminated sites for removing contaminants. These include soil flushing, dual phase extraction, and soil vapor extraction. Among these techniques, soil flushing was the focus of the investigation in this paper. Incorporated technique with PVDs has been used for dewatering from fine-grained soils for the purpose of ground improvement by means of prefabricated vertical drain systems. The laboratory model tests were performed by using the flushing tracer solutions for silty soils and recorded the tracer concentration changes with the elapsed time and flow rates. The modeling was intended to predict the effectiveness and time dependence of the remediation process. Modeling has been performed on the extraction, considering tracer concentration and laboratory model test characteristics. The computer model used herein are SEEP/W and CTRAN/W, this 2-D finite element program allows for modeling to determine hydraulic head and pore water pressure distribution, efficiency of remediation for the subsurface environment. It is concluded that the coefficient of permeability of contaminated soil is related with vertical velocity and extracted flow rate. The vertical velocity and extracted flow rate have an effect on dispersivity and finally are played an important role in-situ soil remediation.

• Applied Biological Chemistry
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• v.8
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• pp.65-73
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• 1967

For the study of method for salt elimination aimed at reforming tidal land into normal paddy fields in a short period with reduction of periods requiring for elimination of saline, CHP (a kind of Ca-hum ate), a soil conditioner made of peat as a main material was tried. In the pot experiment, effect on elimination of salt, improvement of physical-chemical characteristics and rice cultivation test were studied. The results of these tests are as follows: 1, CHP treatment somewhat improves aggregation state with some effect on aggregation. 2. CHP treatment is remarkably effective in permeability which increases with 1.0 percent treatment by three times in percolation rate, and by 4.5 times in volume of leached water respectively. 3. With the increase of CHP amounts, salt was eliminated in short period. When 80% of the total Na was leached in 1.0% CHP-A treated pot, control pot begins permeable. 4. CEC and phosphorous absorption capacity are not influenced by CHP treatment. 5. Growing state of rice is greatly influenced by rainfalls. Growth of rice in tidal land however are almost similar to those in normal paddy fields with layer amounts of CHP treatment. With salt content in the soils, saline hazard and numbers of ineffective stems, amounts of unmatured grain are increased. 6. With the treatment of CHP yields of rough rice were increased. With 0.5% CHP treatment the yields were similar to those of the normal paddy fields. With 1.0% CHP-A treatment, the yields were increased by 15 times more than those of none treated soil and by 25 percent more than normal paddy soils.

• The Journal of Engineering Geology
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• v.28 no.2
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• pp.297-312
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• 2018

In order to assess the safety diagnosis and grouting reinforcement effect of old reservoir facility, local governments and public offices mainly use electrical resistivity survey. However, electrical resistivity survey is a qualitative evaluation that varies the resistivity value by various exploration conditions. It is also difficult to grasp the stiffness change directly related to the stability of reservoir, thus an electrical resistivity survey is not applicable to continuous stability monitoring after grouting. The purpose of this study is to investigate and validate the quantitative evaluation of reinforcement effect of reservoir with cement grouting through shear velocity (Vs), which is closely related to the stiffness (${\mu}$) of the ground. This study was carried out on two reservoir facilities. The reinforcement effect was evaluated by comparing the permeability test, standard penetration test, down-hole test and MASW(Multi-channel Analysis of Surface wave) survey before and after cement grouting. Shear wave velocity changes before and after grouting were analyzed by phase velocity difference and inversion analysis, respectively, and the reliability of the analytical results was evaluated by comparing with field test results. Shear wave velocity increases to 5~10% in case of the D levee, and 10~20% in the levee of H reservoir. These results are showed similar pattern to the field test results.