• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.5
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• pp.77-86
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• 2010

Hydrologic Simulation Program-Fortran (HSPF) coupled with PEST which is optimization program was calibrated and validated at Bochung watershed by using monitoring data of water quantities and nutrient loading. Although the calibrated data were limited, model parameters of each land use type were optimized and coefficient of determinations were ranged from 0.94 to 0.99 for runoff, from 0.89 to 1.00 for TN loading, and from 0.92 to 1.00 for TP loading. The optimized hydrological parameters indicated that the forested land could retain rainfall within soil layer with high soil layer depth and infiltration rate compared with other land use type. Hydrological characteristics of paddy rice field are low infiltration rate and coefficient of roughness. The calibrated parameters related to nutrient loading indicated generation of nutrient pollution from agricultural area including upland and paddy rice field higher than other land use type resulting from fertilizer application. Overall PEST program is useful tool to calibrate HSPF automatically without consuming time and efforts.

• Journal of the Korean Geosynthetics Society
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• v.7 no.4
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• pp.9-18
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• 2008

Shallow slope failures in residual soil during periods of prolonged infiltration are common in Korea. This study examines an infinite slope analysis to estimate the influence of infiltration on surficial stability of slopes by the limit equilibrium method. Approximate method which is based on the Green-Ampt model have been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods. Pradel & Raad method which is devised to predict the depth of wetting front to decomposed granite soil slopes having measured soil-water characteristic curves. To compare the results with those obtained from the Pradel & Raad method, a series of numerical analysis using SEEP/W were carried out. It was found that the stability analysis of unsaturated soils calculated by using the soil-water characteristic curve of decomposed granite soils was found to be a proper analysis for shallow slope failures due to rainfall.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.4
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• pp.1827-1831
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• 1969

Resulties of research on the capacity of ground water of 994 concrete-pipe-wells and 97 infiltration-gallerys in ground-water-developement-works region executed from March to Julyin 1969, in Choong Chung Nam Do, and research on the quality of ground water for 88 wells for home-use around of River Geum Area, are as fellows: (1) Thickness of aquifer is no more than 2.85m averagely even at river-overflowed plain, alluvial plain and valley plain area that are estimated to contain ground water mostly. And so, it is guessed that ground water capacity is not much especially. (2) Soil of aquifer of the above area is sand or gravel and it is estimated to be good for ground water developement and its mean permeability coefficient is bout $2.5{\times}10^{-3}$(m/sec), and its porosity is about 33.9%. (3) The quality of ground water is good for irrigation water exception of delta plain area. Warm water plan is to need for irrigation water when water temperature is less than 19 degrees below zero. (4) Prospect of ground water developement, judging from quality and quantity, expects to lay infiltration gallery under the ground at river bed in order to utilize under-flow-water of river bed, river-overflowed plain, alluvial plain and valley plain that ground level is less than 50m. (5) Collectable water volume of under-flow-water of river bed is about 450 to $750m^3/day$ to be able to irrigate 3ha to 5ha of the cultivated land in case that infiltration gallery length is 50m and its depth is about 5m. (6) Collectable water volume at river-overflowed plain, alluvial plain and valley plain area, is estimated $150m^3/day$ to be able to irrigated 1ha of the cultivated land.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.281-287
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• 2013

Due to its high salt content and poor physical properties in reclaimed tidal lands, it is important to ameliorate soil physical properties to improve the efficiency of desalination. The objective of this study was to evaluate the changes of soil properties at Saemangeum reclaimed tidal saline soil with various soil amendments. Field experiment was conducted at Saemangeum reclaimed tidal land in Korea and the dominant soil series was Munpo series (coarse loamy, mixed, nonacid, Mesic, Typic, Fluvaquents). Woodchips, crushed-stone, oyster shell, coal bottom ash, and rice hull were added as soil amendments and mixed into surface soil to improve soil physical properties. There was large variability in soil hardness, but oyster shell treatment was significantly lower soil hardness at surface layer. Soil hardness was not significantly different below 15 cm depth. Infiltration rate was also significantly greater at oyster shell treatment. This may be due to the leaching of Ca ions from oyster shell and improved soil properties. However, there was no statistical significant difference of the soil bulk density, moisture content, and porosity. Improved physical properties increased desalinization rate in soil and retarded the resalinization rate when evapotranspiration rate was high. Although soil salinity was significantly decreased with oyster shell amendment, soil pH was increased that should be made up as a soil amendment. Our results indicated that oyster shell application increased infiltration rate and improved soil hardness, and thus oyster shell could be used to improve soil salinity level at Saemangeum reclaimed tidal saline soil.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.3
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• pp.290-298
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• 2018

This study aimed to evaluate surface morphology and resin tag penetration of resin infiltration into primary anterior teeth after enamel deproteinization with sodium hypochlorite (NaOCl) prior to phosphoric acid ($H_3PO_4$) etching. Ninety primary anterior teeth with non-cavitated caries lesion were devided five groups according to enamel pretreatment as follows, group I-15% hydrochloric acid (HCl) 2min. ; group II-5.25% NaOCl 1min., 35% $H_3PO_4$ 1min. ; group III-5.25% NaOCl 2min., 35% $H_3PO_4$ 1min. ; group IV-5.25% NaOCl 1min., 35% $H_3PO_4$ 2min. ; group V-5.25% NaOCl 2min., 35% $H_3PO_4$ 2min. Fifteen teeth were examined etched surface structure using field emission-scanning electron microscope. Seventy five teeth were infiltrated with resin, maximum penetration depth and percentage penetration were analysed using dual fluorescence confocal microscopy. As the application time of NaOCl increased, ratio of enamel type I, II were increased. Percentage penetration (PP) was higher in group V than group II, III (p < 0.05). PP of group IV, V did not show any differences. Non-cavitated caries of primary anterior teeth can be treated with resin infiltration. Enamel deproteinization with NaOCl prior to 35% $H_3PO_4$ etching could be an alternative of 15% HCl etching in resin infiltration.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.227-231
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• 2008

The purpose of this study is to clarify the behavior of stranded crude oil and to estimate the restoration of seawater infiltration by application of dispersant as one of cleaning techniques. We made visualization of infiltration process of seawater and stranded crude oil on the sandy beach sediments by using of a model sandy beach. Major conclusions derived from this study are as follows. The seawater infiltration volume was reduced by the stranded crude oil. However, thirty percentage of the sweater infiltration into the sediments was restored by dispersant application to the penetrated oil in sandy beach. The penetration depth of stranded oil were dropped at first falling tide, but were not significantly fluctuated after that. Moreover, oil concentration was most high within the upper 2 cm. The stranded crude oil was broken into small size droplets and dispersed into the sediments by the dispersant application. Therefore, dispersant applications play an important roles in the large increase of surface area of given volume of oil, and it resulted in promoting to biological degradation process at the oil/water interface, dispersing the stranded oil into the water column and restoration of the supplement of the dissolved oxygen and nutrients to the benthic organisms.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.164-168
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• 2014

BACKGROUND: Increase in application of liquid pig manure(LPM) in agriculture as nutritional source has become a social issue due to its influence on water quality. Also, proper application methods have not been developed with respect to indigenous properties of LPM and soil physical properties. Therefore, we conducted this experiment to observe the infiltration characteristics and distribution of dissolved organic compounds of LPM in soils having different soil textures. METHODS AND RESULTS: To do this experiment, we collected three different soils and LPM. We analyzed the physical and chemical properties of both soils and LPM to determine the dilution ratios of LPM. The LPM diluted to 4 different ratios with distilled water was applied to the top of soil column. Infiltration rates were observed by time and depth until the amount of effluent collected from the bottom of the soil columns were stabilized while maintaining the hydraulic head 3 cm above the soil column. The results showed that infiltration rates increased with increasing dilution ratios in the order of sandy, loamy sand, and sandy loam. The time required to reach steady state was increased with decreasing sand contents clay. CONCLUSION: The size and amount of the dissolved organic compounds in LPM that can determine the efficiency as fertilizer and environmental problems as nonpoint pollution source in water quality have not been investigated with respect to behavior and transport of them in soil. Therefore, it requires further research how we can properly apply LPM as valuable fertilizer substitute for inorganic fertilizers.

• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.11-18
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• 2007

Slope failure triggered by rainfall produces severe effects on the serviceability and stability of railway, Therefore, slope stability problem is one of the major concerns on the operation of railway. In this study, the rainfall conditions triggering slopes failure adjacent to railroads are investigated and the numerical analysis approach in consideration of infiltration and limit equilibrium method based upon multiple slip surfaces are proposed. The rainfall conditions triggering slope failure are as follow: cumulative rainfall is in the range of 150~500 mm, and duration is from 3 to 24 hours. Base upon the rainfall conditions, infiltration analysis and limit equilibrium method for infinite slope condition are carried out. The depth of infinite slope is assumed as 2 m and the multiple slip surfaces modeled with 16.7 cm interval from the bottom slip surface located at the 2 m depth. The assumed bottom slip surface is the location at which factor of safety is converging. The proposed approach shows more reasonable results than the results from the general codes assuming water table at slope surface. In addition, three dimensional plot of cumulative rainfall, rainfall duration, and factor of safety shows that slope stability analysis in consideration of rainfalll must account for cumulative rainfall (rainfall duration).

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.257-265
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• 2020

This study was performed to evaluate the restoration combined with resin infiltration (RI) of early cavitated smooth surface caries lesion in terms of microleakage. Flowable resin and resin-modified glass ionomer cement (RMGIC) were compared. Sound 20 extracted 3rd molars were divided into 2 groups randomly. Artificial decalcified lesion was induced. Cavities were prepared on the mesial and distal surfaces, and randomly set as experimental and control group. RI was applied to the experimental group before cavity restoration. The control group was restored without RI. In group I and II, flowable resin and RMGIC was used for restoration respectively. After thermocycling and silver nitrate immersion, microleakage was assessed by μ-CT. Depth of microleakage was lower in experimental group than control group only in group II (p = 0.05). Microleakage depth was lower in group II than group I in both experimental and control groups (p = 0.05). RI pretreatment before restoration of early cavitated caries lesions might reduce the microleakage and help long-term maintenance of restoration. In this study, RMGIC was less polymerization shrinkage. Restoration with RMGIC after RI pretreatment reduced the microleakage of the restoration compared to the flowable resin.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.1
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• pp.1-10
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• 2012

The concept of resin infiltration which was born in an innovative philosophy to arrest the incipient caries. However, the structural changes of resin infiltrated lesions have not yet explained completely. The liquid resin might contribute not only to maximizing the penetration but to deteriorating physical stability. This study was performed to examine some physical and histological features of resin infiltrated incipient carious lesions. With the specimen of resin infiltrated lesions, microhardness by nanoindentation in depth profile, morphology of resin tags were revealed after HCl dissolution, and degree of microleakage were assessed. The percentage of microhardness of surface layer and lesion body of untreated specimen to sound enamel was 64.6% and 24.6% respectively, while that of resin-infiltrated lesions was 72.1%, showing significant difference (p<0.05). The resin tags observed under SEM had relatively homogeneous length of 433(282~501) ${\mu}m$ on the average. Among 20 specimens for microleakage assessment, 13 specimens showed no leakage while 5 and 2 showed leakage into outer and inner half of lesion respectively. It was thought the infiltrant resin penetrates deeply and homogeneously into lesion body and improves its hardness with relatively good physical stability.