• Membrane Journal
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• v.17 no.4
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• pp.302-310
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• 2007

The effects of various system parameter on the absorption of sulfur dioxide into the absorbent liquid were investigated in a circulatory porous polymer membrane contactor. A feed gas and an absorbent used in the study were the gas mixture of air and $SO_2$ and the $Na_2SO_3$ aqueous solution, respectively. The separation of sulfur dioxide was measured in terms of the concentration of $Na_2SO_3$ absorbent, the concentration of sulfur dioxide, the feed flow rate, the absorbent velocity and the different membrane material. As the concentration of absorbent increased from 0.05 to 0.2 M, the removal efficiency increased from 74 to 100%. By increasing the concentration of sulfur dioxide from 700 to 2,500 ppm, the removal efficiency decreased from 100 to 75%. Also as the absorbent velocity increased from 2.5 to 15 mL/min, the removal efficiency increased from 85 to 100%. As the porosity of the membrane increased, the removal efficiency increased.

• Membrane Journal
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• v.28 no.5
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• pp.320-325
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• 2018

The sorption amounts of butanol/water and isopropanol/water solution on the surface modified with FASs (fluoroalkylsilanes) hydrophobic membrane were measured and analyzed using Hansen's solubility parameters. The difference of the solubility parameter of butanol (${\delta}_t=20.4$) and that of the surface modified with FASs hydrophobic membrane (${\delta}_t=16.9$) was greater than the case of isopropanol (${\delta}_t=24.6$), which might explain the result that the sorption amount of butanol was much higher than that of isopropanol. We might also explain the effect of the polar force (${\delta}_p$) on the sorption amount. The difference (${\Delta}$) between FASs polar force (${\delta}_p=4.6$) and butanol polar force (${\delta}_p=6.3$) was much smaller than that between FASs polar force (${\delta}_p=4.6$) and isopropanol polar force (${\delta}_p=9.0$), which meant that the interaction of butanol-FASs was much greater than that of isopropanol-FASs, and resulted in greater sorption amount of butanol on the FASs. This study showed Hansen's solubility parameters might be used for analysis of sorption characteristics of alcohol on membrane and solubility of solute in solvent.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.4
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• pp.108-114
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• 1980

A deterministic conceptual erosion model which simulates detachment, entrainment, transport and deposition of eroded soil particles by rainfall impact and flowing water is presented. Both upland and channel phases of sediment yield are incorporated into the erosion model. The algorithms for the soil erosion and sedimentation processes including land and crop management effects are taken from the literature and then solved using a digital computer. The erosion model is used in conjunction with the modified Kentucky Watershed Model which simulates the hydrologic characteristics from watershed data. The two models are linked together by using the appropriate computer code. Calibrations for both the watershed and erosion model parameters are made by comparing the simulated results with actual field measurements in the Four Mile Creek watershed near Traer, Iowa using 1976 and 1977 water year data. Two water years, 1970 and 1978 are used as test years for model verification. There is good agreement between the mean daily simulated and recorded streamflow and between the simulated and recorded suspended sediment load except few partial differences. The following conclusions were drawn from the results after testing the watershed and erosion model. 1. The watershed and erosion model is a deterministic lumped parameter model, and is capable of simulating the daily mean streamflow and suspended sediment load within a 20 percent error, when the correct watershed and erosion parameters are supplied. 2. It is found that soil erosion is sensitive to errors in simulation of occurrence and intensity of precipitation and of overland flow. Therefore, representative precipitation data and a watershed model which provides an accurate simulation of soil moisture and resulting overland flow are essential for the accurate simulation of soil erosion and subsequent sediment transport prediction. 3. Erroneous prediction of snowmelt in terms of time and magnitute in conjunction with The frozen ground could be the reason for the poor simulation of streamflow as well as sediment yield in the snowmelt period. More elaborate and accurate snowmelt submodels will greatly improve accuracy. 4. Poor simulation results can be attributed to deficiencies in erosion model and to errors in the observed data such as the recorded daily streamflow and the sediment concentration. 5. Crop management and tillage operations are two major factors that have a great effect on soil erosion simulation. The erosion model attempts to evaluate the impact of crop management and tillage effects on sediment production. These effects on sediment yield appear to be somewhat equivalent to the effect of overland flow. 6. Application and testing of the watershed and erosion model on watersheds in a variety of regions with different soils and meteorological characteristics may be recommended to verify its general applicability and to detact the deficiencies of the model. Futhermore, by further modification and expansion with additional data, the watershed and erosion model developed through this study can be used as a planning tool for watershed management and for solving agricultural non-point pollution problems.

• 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.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.121-131
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• 2007

Despite the close linkage in changes between the ecological and hydrological processes in forest ecosystems, an integrative approach has not been incorporated successfully. In this study, based on the vegetation and hydrologic data of the Gwangneung headwater catchment with the Geographic Information System, we attempted such an integrated approach by employing the Regional Hydro-Ecologic Simulation System (RHESSys). To accomplish this, we have (1) constructed the input data for RHESSys, (2) developed an integrated calibration system that enables to consider both ecological and hydrological processes simultaneously, and (3) performed sensitivity analysis to estimate the optimum parameters. Our sensitivity analyses on six soil parameters that affect streamflow patterns and peak flow show that the decay parameter of horizontal saturated hydraulic conductivity $(s_1)$ and porosity decay by depth (PD) had the highest sensitivity. The optimization of these two parameters to estimate the optimum streamflow variation resulted in a prediction accuracy of 0.75 in terms of Nash-Sutcliffe efficiency (NSec). These results provide an important basis for future evaluation and mapping of the watershed-scale soil moisture and evapotranspiration in forest ecosystems of Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.88-99
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• 2007

Soil moisture is one of the essential components in determining surface hydrological processes such as infiltration, surface runoff as well as meteorological, ecological and water quality responses at watershed scale. This paper discusses soil moisture transfer processes measured at hillslope scale in the Gwangneung forest catchment to understand and provide the basis of stochastic structures of soil moisture variation. Measured soil moisture series were modelled based upon the developed univariate model platform. The modeling consists of a series of procedures: pre-treatment of data, model structure investigation, selection of candidate models, parameter estimation and diagnostic checking. The spatial distribution of model is associated with topographic characteristics of the hillslope. The upslope area computed by the multiple flow direction algorithm and the local slope are found to be effective parameters to explain the distribution of the model structure. This study enables us to identify the key factors affecting the soil moisture distribution and to ultimately construct a realistic soil moisture map in a complex landscape such as the Gwangneung Supersite.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.517-526
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• 2019

The purpose of this study is to find the optimal method for clinical application by analyzing image quality and radiation output according to parameter combination when using the Automatic Exposure Control (AEC). The experimental method combines 70, 81 kVp with sensitivity S200, S400, S800 and S1000 of the Automatic Exposure Control for Entrance Surface Dose (ESD), current volume, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR), Time-to-Radiation Dose Curve in abdomen and pelvis. And then, image quality and radiation output stability were evaluated. As a results, Entrance Surface Dose, current volume, Signal to Noise Ratio, Contrast to Noise Ratio decreased as the tube voltage and sensitivity were set higher. In addition, the higher tube voltage and sensitivity, the Time-to-Radiation Dose Curve showed a poor output stability. In conclusion, the higher the combination of tube voltage and sensitivity in the use of Automatic Exposure Control, the more problems can be seen in image quality and stability of the radiation output. Therefore, a relatively low combination of tube voltage and sensitivity showed that the image quality and radiation output stability could be optimized by minimizing the error range that would occur when the detector recognized a combination of parameters.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.2 s.9
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• pp.99-110
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• 2003

In this study, lightening material weight and normalizing structure of preventing system of landslide soil-rock in trench excavation was tried with focusing in safety construction availability and workability. In other words, risk estimate, safety management method investigation, applicability of bracing material and mechanical stability of bracing structure was studied. From these result, structural stability and structural analysis of light weight bracing structure was carried out with common structural analysis program, for examining movement mechanism of bracing structure and normalization of standard. The result are summarized as following. (1) Mechanical ability of bracing members and soil pressure parameter acting to member for ensuring mechanical propriety of bracing structural and useful of new material considering soil mechanics boundary were proposed. Also theory and method of analysis of bracing structural were proposed. (2) As a result of the structure analysis of geographical profile for light pannel used FRP as hard clay mechanical characteristics(bending moment, shear force, axial force) of panel were changed according to groundwater level and it is proved that the result of mechanical analysis is within allowable stress. Thus, light pannel is available for bracing structure in trench excavation.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.11
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• pp.626-633
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• 2017

The present study investigated the effect of a water-washing process, which is part of the acid hydrometallurgical process for recovery of high purity of zinc, on the removal of alkali metals and chlorides (Na, K, Ca, Cl) from Electric arc furnace dust (EAFD). Two EAFD samples with different properties were characterized by particle size, XRD and element analysis, and their washing efficiencies (%) on alkali metals and chlorides were compared according to pH, washing time, liquid to solid (L/S) ratio and number of washings. The results show that the alkali metals and chlorides could be effectively removed by the washing (at L/S ration of 3 for more than 30 min., pH 10~11) while minimizing loss of zinc (<0.1%), in which the washing efficiency was Na-78%, K-76%, Cl >99%, respectively. Na and K could be removed up to 97% and 89% respectively by 3 times of repeated washings. With increased sample volume (10 times) of the mixed (1:1, w/w) sample with two types of EAFD, it was confirmed that the pH(10~11) can be used as the main process control parameter for the washing of the alkali metals regardless of EAFD properties.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.1 s.20
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• pp.49-58
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• 2006

Rainfall-runoff characteristics are analysed based on the geomorphological instantaneous unit hydrograph(GIUH) derived by geomorphological parameters using geographical information system in watershed ungaged or deficient of field data. Observed data of Seom river experiment watershed at upstream of Hoengseong dam and variable slope method for hydrograph separating of direct non are used. The 4th stream order of Seom river experimental watershed is developed with a regular correlation referred to the Horton-Strahler's law of stream order. The characteristic velocity to determine shape parameter of GIUH is 1.0m/s and its equation is modified for accurate results. Hydrograph at the outlet of 4th stream order of Maeil gage station and at the outlets of 3rd stream order of Sogun and Nonggeori gage stations show a little differences in falling limb of hydrograph but agree well to the observed data in general. The results by hydrological routing with HEC-HMS to the outlet of 4th stream order of Maeil gage station which the hydrograph by GIUH obtained at Sogun and Nonggeori gage stations of 3rd stream oder are applied as upstream inputs give better agreement with observed data than those by hydrograph by GIUH obtained at Maeil gage station of 4th stream order. In general, the rainfall-runoff by GIUH has applicability to the watershed routing of ungaged project regions.