• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.6
• /
• pp.144-152
• /
• 2003

Laboratory experiments were carried out to investigate the influence of pore water contamination on the treatment effect of sandy soil which was solidified by Portland cement. In the experiments, setting time of hydraulic cement that was mixed with contaminated mixing water was measured using Vicat equipment and observed the tendency of setting process with the kind of contaminants, organic or inorganic components. It was shown that organic contaminants of the mixing water affect largely on the initial setting process of hydraulic cement and inorganics, expecially heavy metals, did not affect on the initial setting process, otherwise it was appeared that setting time of the sandy soil that was contaminated with inorganic components was apparently faster than the sandy soil that did not include inorganic components even though organic concentrations was relatively low level (COD=200∼300) in the mixing water. The results of unconfined compression strength test (UCST) were well consistent with the results of Vicat equipment test.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.215-218
• /
• 2003

In order to study the frost heaving characteristics of soil stabilitized with a quick lime, a cement and a briquette ash, frost heaving tests were performed with 2 kinds of soil sampled at Chonbuk-Do area. Frost heaving of no-stabilizing soil compacted with water content greater than optimum water content was increased as the frost period was increased but in case of samples with water content smaller than optimum water content, the frost period gave no affect about increase and decrease of the frost heaving. Both frost heaving of stabilizing and no-stabilizing soil with water content greater than optimum water content was decreased with the increase of the repetition number of freezing and thawing. There was no increase or decrease of frost heaving in the frost heaving test after 5 times of freezing and thawing.

• Journal of Korean Society on Water Environment
• /
• v.32 no.1
• /
• pp.60-69
• /
• 2016

In this study, we estimated root zone soil moisture dynamics using remotely sensed (RS) data. A soil moisture data assimilation scheme was used to derive the soil and root parameters from MODerate resolution Imaging Spectroradiometer (MODIS) data. Based on the estimated soil/root parameters and weather forcings, soil moisture dynamics were simulated at spatio-temporal scales based on a hydrological model. For calibration/validation, the Little Washita (LW13) in Oklahoma and Chungmi-cheon/Seolma-cheon sites were selected. The derived water retention curves matched the observations at LW 13. Also, the simulated soil moisture dynamics at these sites was in agreement with the Time Domain Reflectrometry (TDR)-based measurements. To test the applicability of this approach at ungauged regions, the soil/root parameters at the pixel where the Seolma-cheon site is located were derived from the calibrated MODIS-based (Chungmi-cheon) soil moisture data. Then, the simulated soil moisture was validated using the measurements at the Seolma-cheon site. The results were slightly overestimated compared to the measurements, but these findings support the applicability of this proposed approach in ungauged regions with predictable uncertainties. These findings showed the potential of this approach in Korea. Thus, this proposed approach can be used to assess root zone soil moisture dynamics at spatio-temporal scales across Korea, which comprises mountainous regions with dense forest.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.18 no.1
• /
• pp.13-23
• /
• 2015

This study was performed to compare the effects of different drainage layers on tree growth at the exposed sites of Saemangeum sea dike. 4 types of drainage layers including control(dredged soil), specially prepared bark, gravel, and wood chip were set in 150~165cm depth of soil. Pinus thunbergii and Celtis sinensis were planted after 9 months of soil treatment. Electrical conductivity(EC) of soil in all treated plots were decreased under $4dS{\cdot}m^{-1}$, and NaCl(%) was decreased under 0.05% after 1 year from soil treatment. Soil moisture at the 120cm depth of the bark treated plot was higher than that of the 180cm soil depth, below the drainage layer. It is considered that vertical mobility of water was inhibited. Organic matter(OM) at the 120cm soil depth increased at bark and wood chip treated plots. Survival rates after 4 years of P. thunbergii and C. sinensis were 100% in all treatments. The height of P. thunbergii was not significantly different among the treatments while the height of C. sinensis was significantly different among the treatments and it was highest at the bark treated plot.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.5
• /
• pp.27-35
• /
• 2004

The goal of this study is to investigate the feasibility of the reference state approach in determining the generalized soil-water characteristic curve that is essential fur characterization of unsaturated soil behavior. The soil-water characteristic curves are obtained from a number of specimens of fine-grained residual soils compacted with different void ratios. Based on the experimental test results, the feasibility of using the liquid limit state as the reference state for predicting the soil-water characteristic curve is verified. Finally, through the regression analysis of experimental data using the equation of Fredlund and Xing (1994), a reliable method is proposed to predict the generalized soil-water characteristic curve of fine-grained residual soils using the liquid limit state as the reference state.

• Journal of Environmental Science International
• /
• v.3 no.4
• /
• pp.409-416
• /
• 1994

This study was Performed to evaluate the contents of heavy metals in water, sediment and soil of the 7 different sampling points along the West Nakdong river, The results were as follows: the concentrations of Zn, p, Pb, Cd, Mn, Cu and As in the sediment were 197.48, 551.85, 67.01, 2.54, 491.39, 42.95 and 10.52ppm, respectively. The concentrations of Zn, p, Pb, Cd, Mn, Cu and As in the soil was 83.32, 482.89, 17.15, 1.02, 226.02, 26.15 and 7.29ppm, respectively. The concentration ratios of heavy metals In the water to the sediment were 593 - 12700 (Cd >> Cu > Zn > Mn > As > Pb) and that of the water to the soil were 152 - 5100 (Cu > Cd > Zn > Mn > As >Pb). The correlation coefficients of Cu and Pb weve high among the water, sediment and soil. Because the accumulation amounts of heavy metal in the sediment were high, the concentration of heavy metals in the sediment was higher than in soil. The correlation coefficient of heavy metals among water, sediment and soil was high (0.79 - 0.95). Key Words Distribution Characteristics, heavy metals, West Nakdong River.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.55 no.3
• /
• pp.91-104
• /
• 2013

The objectives of this study were to monitor and assess the environmental impacts of indirect wastewater reuse on water quality and soil in paddy fields. Yongin monitoring site (YI) irrigated from agricultural reservoir and Osan monitoring site (OS) irrigated with treated wastewater diluted with stream water were selected as control and treatment, respectively. Monitoring results for irrigation water quality showed a significant statistical difference in salinity, exchangeable cation and nutrients. Pond water quality showed a similar tendency with irrigation water except for the decreased difference in nutrients due to the fertilization impact. Soil chemical properties mainly influenced by fertilization activity such as T-N, T-P, and $P_2O_5$ were changed similarly in soil profiles of both monitoring sites, while the properties, EC, Ca, Mg, and Na, mainly effected by irrigation water quality showed a considerable change with time and soil depth in treatment plots. Heavy metal contents in paddy soil of both control and treatment did not exceed the soil contamination warning standards. This study could contribute to suggest the irrigation water quality standards and proper agricultural practices including fertilization for indirect wastewater reuse, although long-term monitoring is needed to get more scientific results.

• Ocean Systems Engineering
• /
• v.5 no.1
• /
• pp.1-19
• /
• 2015

The water jetting system for a jack-up spudcan requires the suitable design considering the platform/spudcan particulars, environments, and soil conditions, either the surficial clay or surficial sand. The usage of water jetting depends critically on soil conditions. The water jetting is usually used for the smooth and fast extraction of the spudcan in the surficial clay condition. It is also required for inserting spudcan up to the required depth in the surficial sand condition, which is investigated in this paper. Especially, it should be very careful to use the water jetting during an installation of spudcan in the surficial sand condition, because there is a risk of overturning accident related to the punch-through. Therefore, in this study, the effect of water jetting flow rate and time on the change of soil properties and penetration resistance is analyzed to better understand their interactions and correlations when inserting the spudcan with water jetting in surficial sand condition. For the investigation, a wind turbine installation jack-up rig (WTIJ) is selected as the target platform and the multi layered soil (surficial sand overlaying clays) is considered as the soil condition. The environmental loading and soil-structure interaction (SSI) analysis are performed by using CHARM3D and ANSYS. This kind of investigation and simulation is needed to decide the proper water jetting flow rate and time of spudcan for the given design condition.

• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.6
• /
• pp.812-822
• /
• 2010

Water management is the most important and difficult problems in crop cultivation. The farmers are doing irrigation, those when to irrigate and how much to irrigate, depending on their experiences. The irrigation manual as water saving is possible, those irrigation interval and amount of irrigation, are developed based on the lysimeter experiments carried out by the RDA for 11 years about potential evapotranspiration, crop coefficient. The manual can be used with easy to the farmer without soil sampling and any kinds of sensors measuring soil water status.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.281-281
• /
• 2015

Shallow landslide often occurs in areas of this topography where subsurface soil water flow paths give rise to excess pore-water pressures downslope. Recent hillslope hydrology studies have shown that subsurface topography has a strong impact in controlling the connectivity of saturated areas at the soil-bedrock interface. In this study, the physically based SHALSTAB model was used to evaluate the effects of three soil thicknesses (i.e. average soil layer, soil thickness to weathered soil and soil thickness to bedrock soil layer) and subsurface flow reflecting three soil thicknesses on shallow landslide prediction accuracy. Three digital elevation models (DEMs; i.e. ground surface, weathered surface and bedrock surface) and three soil thicknesses (average soil thickness, soil thickness to weathered rock and soil thickness to bedrock) at a small hillslope site in Jinbu, Kangwon Prefecture, eastern part of the Korean Peninsula, were considered. Each prediction result simulated with the SHALSTAB model was evaluated by receiver operating characteristic (ROC) analysis for modelling accuracy. The results of the ROC analysis for shallow landslide prediction using the ground surface DEM (GSTO), the weathered surface DEM and the bedrock surface DEM (BSTO) indicated that the prediction accuracy was higher using flow accumulation by the BSTO and weathered soil thickness compared to results. These results imply that 1) the effect of subsurface flow by BSTO on shallow landslide prediction especially could be larger than the effects of topography by GSTO, and 2) the effect of weathered soil thickness could be larger than the effects of average soil thickness and bedrock soil thickness on shallow landslide prediction. Therefore, we suggest that using BSTO dem and weathered soil layer can improve the accuracy of shallow landslide prediction, which should contribute to more accurately predicting shallow landslides.