• The Journal of Engineering Geology
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• v.15 no.3
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• pp.303-307
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• 2005

Severe drawdown of Groundwater level(CWL) is observed from the analysis of the relationship between precipitation and CWL data during dry seasons in Ssangchun watershed. For Ssangchun watershed, the correlation was the strongest when we apply 70 day Moving Average(MA) for Groundwater dam Operation Index(COI) calculation. To determine the critical infiltration, which is the spatially averaged maximum daily infiltration, a certain value is fixed as the maximum infiltration and precipitation data is modified. COI is recalculated after the data modification and the correlation between COI and GWL is checked. The critical infiltration is determined when the best correlation is obtained after we repeat the above procedure with different fixed values. The critical infiltration is 40m for Ssangchun watershed. The correlation between CWL and COI is higher when we consider critical infiltration than we neglected it.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.313-321
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• 2009

The relationship between precipitation and groundwater level and the correlation between the moving average of precipitation and goundwater level were analyzed for the Han river watershed in Korean peninsular. Fourteen regions in the watershed were selected and there were somewhat different patterns of seasonal fluctuation of groundwater level data. The groundwater level data tends to decrease in dry spell and increase in wet spell however the range between maximum and minimum values is quite different for each gauging point. We could have stronger correlation between groundwater level for fractured rock aquifer and the moving average of precipitation than the groundwater level for alluvial aquifer. The critical infiltration, which is the maximum daily infiltration averaged throughout watershed, value is turned out to have the range of 10 to 90 mm. We could have stronger correlation when we consider critical infiltration and modify the original precipitation data than we use original precipitation data. We also could have higher correlation coefficient when we consider snowmelt effect for the watershed that has considerable snow event.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.67-74
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• 2019

Apparent changes in the natural hydrologic cycle causing more frequent floods in urban areas and surface water quality impairment have led stormwater management solutions towards the use of green and sustainable practices that aims to replicate pre-urbanization hydrology. Among the widely documented applications are infiltration techniques that temporarily store rainfall runoff while promoting evapotranspiration, groundwater recharge through infiltration, and diffuse pollutant reduction. In this study, a laboratory-scale infiltration device was built to be able to observe and determine the factors affecting flow variations and corresponding solids removal through a series of experiments employing semi-synthetic stormwater runoff. Results reveal that runoff and solids reduction is greatly influenced by the infiltration capability of the underlying soil which is also affected by rainfall intensity and the available depth for water storage. For gravel-filled structures, a depth of at least 1 m and subsoil infiltration rates of not more than 200 mm/h are suggested for optimum volume reduction and pollutant removal. Moreover, it was found that the length of the structure is more critical than the depth for applications in low infiltration soils. These findings provide a contribution to existing guidelines and current understanding in design and applicability of infiltration systems.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1237-1245
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• 2018

We developed the assessment method for weekly groundwater resources management vulnerability. To consider the effect of precipitation on groundwater level, we calculated correlation coefficient between groundwater level and precipitation applying critical infiltration concept. We developed the vulnerability assessment criteria and calculated weights for criteria using the entropy method. Weekly groundwater resources management vulnerability of small administrative districts were estimated using developed method in this research. The developed method can be a basis for the establishment of the spatio-temporal groundwater resources management plan.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.130-130
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• 2021

The increasing effect of urbanization has been more apparent through flooding and downstream water quality especially from heavy rainfalls. In response, stormwater runoff management solutions have focused on runoff volume reduction and treatment through infiltration. However, there are areas with low infiltration soils or are experiencing more dry days and even drought. In this study, a lab-scale infiltration system was used to compare the applicability of two types of soil as base layer in gravel-filled infiltration systems with emphasis on runoff capture and suspended solids removal. The two types of soils used were sandy soil representing a high infiltration system and clayey soil representing a low infiltration system. Findings showed that infiltration rates increased with the water depth above the gravel-soil interface indicating that the available depth for water storage affects this parameter. Runoff capture in the high infiltration system is more affected by rainfall depth and inflow rates as compared to that in the low infiltration system. Based on runoff capture and pollutant removal analysis, a media depth of at least 0.4 m for high infiltration systems and 1 m for low infiltration systems is required to capture and treat a 10-mm rainfall in Korea. A maximum infiltration rate of 200 mm/h was also found to be ideal to provide enough retention time for pollutant removal. Moreover, it was revealed that low infiltration systems are more susceptible to horizontal flows and that the length of the structure may be more critical that the depth in this condition.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.57-63
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• 1999

The fabrication of $Al_2O_3/Al$ composites by pressureless infiltration technique was made to investigate the effects of processing variables such as content of Mg, processing temperature and time on the infiltration behavior of molten Al and microstructure. When the pure Al was infiltrated into mixtures of Mg and $Al_2O_3$ powder, processing temperature required to spontaneous infiltration was decreased and critical processing temperature and Mg content were $700^{\circ}C$ and 3wt% respectively. The content of Mg was found the most powerful variable for infiltration of molten Al. The infiltration ratio increased with Mg content and processing temperature, however the $Al_2O_3/Al$ composites which were fabricated by high Mg content and processing temperature resulted in non uniform dispersion of $Al_2O_3$ particles by excessive interfacial reaction. XRD pattern indicated that $MgAl_2O_4$ and AIN was observed at the interface of $Al_2O_3$ particles and in the Al matrix as reaction products.

• Journal of Korea Foundry Society
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• v.12 no.2
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• pp.149-154
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• 1992

The wetting behaviour of SiC/Al-Li composite interface has been investigated by using an infiltration method. The critical pressure for melt infiltration into SiC particulate preform has been determined by measuring the melt infiltration distance changes with the variation of applied pressure. The threshold pressure of pure Al, Al-0.2wt%Li, Al-0.5wt%Li for melt infiltration are 3.94, 3.93, $3.7Kg/cm^2$ respectively, which implies a slight improvement in wettability of SiC/Al composite by addition of Li. The threshold pressure for melt infiltration also changes with the variation of other parameters such SiC particulate size, SiC particulate fraction and melt temperature.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.393-403
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• 2008

The relationship between precipitation and groundwater level and the correlation between the moving average of precipitation and goundwater level were analyzed for the southern area of Korean peninsular. There were somewhat different patterns of seasonal fluctuation of groundwater level data. The groundwater level data tends to decrease in dry spell and increase in wet spell however the range between maximum and minimum values is quite different for each gauging point. The maximum correlation coefficient for each gauging station is obtained in a range of 20- to 130-day moving average period of precipitation. The critical infiltration, which is the maximum daily infiltration averaged throughout watershed, value is turned out to have the range of 10 to 90 mm and the moving average period is 10 to 150 days. We could have stronger correlation when we consider critical infiltration and modify the original precipitation data than we use original precipitation data.

• Tuberculosis and Respiratory Diseases
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• v.82 no.3
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• pp.264-265
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• 2019

• Progress in Superconductivity
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• v.11 no.1
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• pp.42-46
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• 2009

With an aim of comparison, single grain Y-Ba-Cu-O (YBCO) bulk superconductors were fabricated using a liquid infiltration growth (LIG) process and a conventional melt growth (MTG) process with top seeding. The MTG process uses an $YBa_2Cu_3O_{7-x}$(Y123) powder as a precursor, while the LIG process uses $Y_2BaCuO_5(Y211)/Ba_3Cu_5O_8(Y035)$ pre-forms. The growth of a single Y123 domain on the top seed was successful in the both processes. Different feature between the two processes is the interior microstructure regarding the critical current density ($J_c$). The LIG-processed YBCO sample showed a lower porosity, more uniform distribution of Y211 particles and the enhanced Y211 refinement compared to the conventional MTG process. The $J_c$ improvement in the LIG process is attributed to the dispersion of finer Y211 particles as well as lower porosity within the Y123 superconducting matrix.