• Economic and Environmental Geology
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• v.44 no.4
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• pp.289-302
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• 2011

Since the frequency of the earthquake occurrence in Korean peninsular is continuously increasing, the possibility that massive landslides are triggered by earthquake is also growing in Korea. Previously, the landslide is known to be induced by large magnitude earthquake, whose magnitude is larger than 6.0. However, the landslide can be induced by only small magnitude earthquake, especially in the fully saturated soil. Therefore, the susceptibility of landslide caused by small magnitude earthquake in fully saturated soil is analyzed in this study. For that, the topographical and geological characteristics of the site were obtained and managed by GIS software. In the procedure of the study, slope angle, cohesion, friction angle, unit weight of soil were obtained and constructed as a spatial database layer. Combining these data sets in a dynamic model based on Newmark's displacement analysis, the landslide displacements were estimated in each grid cell. In order to check out the possibility of the earthquake induced landslides, the level of the groundwater table is varied from dry to 80% saturated soil. In addition, in order to analyze the effect of the magnitude of earthquake and distance to epicenter, four different earthquakes epicenters were considered in the study area.

• Journal of the Korean Geographical Society
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• v.42 no.3 s.120
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• pp.344-354
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• 2007

Estuarine wetlands for 33 watersheds in the Han River estuary were delineated on topographic maps from the 1910s, 1970s, and 2000s. Then, these data were used to address the issue of spatial distribution and temporal variation. Watershed characteristics such as drainage density, location, watershed size, slope, and elevation were identified for each watershed to determine the relationship between watershed characteristics and spatial distribution of estuarine wetlands. The analysis of estuarine wetlands indicated that wetlands in the estuary had declined gradually between the 1910s and the 1970s, although most wetlands were lost since the 1970s mainly caused by the large development projects related to urban expansion in metropolitan Seoul. The sediment composition and formation processes of the wetlands differed with watershed location; mud flats dominate in the lower part of the estuary, and relatively more sandy and emergent-plant wetlands occur near the main channel and tributaries of the Han River. Relatively more estuary wetlands occur in large watersheds, which have high slopes and low elevations. Estuarine wetlands have been lost dramatically in the densely populated watershed regions (i.e., Han River Seoul, Han River Goyang, West Han River), while relatively more wetlands have remained in undeveloped regions, including the Lower Imjin River and Lower Han River. In particular, anthropogenic disturbance has played an important role in the loss of wetland through the conversion of wetland into agricultural and developed land.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.540-545
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• 1992

Kinetics and mechanism on the solvent extraction of nickel(Ⅱ) with 8-hydroxyquinoline (HOx) was studied spectrophotometrically. Absorbance variation was measured by changing the 8-hydroxyquinoline concentration in the chloroform organic phase and the pH values in the aquous phase. By analyzing absorbance data the reaction rate was found to be the first order for 8-hydroxyquinoline concentration and the inverse first one for [H$^+$]. Therefore the rate determining step of the extraction reaction is the formation of the one-to-one metal chelate NiOx$^+$ and the rate equation is as follows; -d[Ni$^{2+}$]/dt = k[Ni$^{2+}$][Ox$^-$] = k'[Ni$^{2+}$][HOx]$_0$/[H$^+$]. The value of k' was evaluated from the slope of plot of log [Ni$^{2+}$]$_0$/[Ni$^{2+}$]$_t$ versus time and the rate constant k was calculated according to the equation k' = k ${\times}$ K$_{HOx}$ / K$_{D,HOx}$. From the temperature dependence of the extraction rate, the activation energy E$_a$ = 6.26 kcal/mol is calculated, and activation parameters, ${\Delta}$G$^{\neq}_{298}$ = 6.59 kcal/mol, ${\Delta}$H$^{\neq}_{298}$ = 5.68 kcal/mol, ${\Delta}$S$^{\neq}_{298}$ = -3.09 eu/mol are estimated.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.66-73
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• 2007

The various output characteristics of a pulsed Ti:sapphire laser oscillator with a plane-parallel resonator, pumped longitudinally by the second harmonic wave of a Nd:YAG laser, and the output of a Ti:sapphire laser amplifier operated along the single path of the oscillator beam were investigated and analyzed. In the case of the oscillator, we measured the spectrum, the pulse buildup time, the temporal duration time of the pulse, and the output energy according to the variation of the pumping energy, resonator length, and the reflectance of the output coupler. And, in the case of the amplifier, we investigated and analyzed the output energy of the amplifier as a function of the time difference between the two pump beams of the oscillator and the amplifier, the pumping energy of the oscillator, and the pumping energy of the amplifier When pump energies of both the oscillator and the amplifier were 18 mJ/pulse, we could find that the output energy of the amplifier increased linearly and gradually up to the time difference of 35 ns. Finally, we determined that the slope efficiencies of the oscillator and the amplifier were 23.5 % and 11.6 %, respectively.

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.837-847
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• 2017

Land Surface Model (LSM) was developed for the Soyang river basin located in Korean Peninsula to clarify the spatio-temporal variability of hydrological weather parameters. Variable Infiltration Capacity (VIC) model was used as a LSM. The spatial resolution of the model was 10 km and the time resolution was 1 day. Based on the daily flow data from 2007 to 2010, the 7 parameters of the model were calibrated using the Isolated Particle Swarm Optimization algorithm and the model was verified using the daily flow data from 2011 to 2014. The model showed a Nash-Sutcliffe Coefficient of 0.90 and a correlation coefficient of 0.95 for both calibration and validation periods. The hydrometeorological variables estimated for the Soyang river basin reflected well the seasonal characteristics of summer rainfall concentration, the change of short and shortwave radiation due to temperature change, the change of surface temperature, the evaporation and vegetation increase in the cover layer, and the corresponding change in total evapotranspiration. The model soil moisture data was compared with in-situ soil moisture data. The slope of the trend line relating the two data was 1.087 and correlation coefficient was 0.723 for the Spring, Summer and Fall season. The result of this study suggests that the LSM can be used as a powerful tool in developing precise and efficient water resources plans by providing accurate understanding on the spatio-temporal variation of hydrometeorological variables.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.173-185
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• 2014

Climate change has caused detrimental phenomena such as heavy rainfall which could aggravate soil erosion. Accordingly, it is needed to evaluate the groundwater recharge, baseflow, and soil erosion for the efficient management of water resources and quality. In this study, future climate change scenarios were applied to the H aean-myeon watershed which is a steep sloping watershed in South Korea to analyze groundwater recharge, baseflow, sediment. Also, the variation of groundwater recharge, baseflow, sediment was analyzed according to the change of slope (5 %). Simulated periods were divided into three terms (2013 ~ 2040 years, 2041 ~ 2070 years, 2071 ~ 2100 years). As a result of this study, average groundwater recharge and baseflow increased by 50 %, 42 %, and sediment decreased by 72 %, respectively. In these regards, the suggested method will positively contribute to hydro-ecosystem and reduction of muddy water at a steep sloping watershed.

• 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.

• Archives of Pharmacal Research
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• v.26 no.1
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• pp.70-75
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• 2003

The objective of the present study was to investigate the uptake process of 4-Phenylazobenzoxycarbonyl-Pro-Leu-Gly-Pro-D-Arg (Pz-peptide), a hydrophilic and collagenase-labile pentapeptide, by isolated hepatocytes. For comparison, the uptake of Pz-peptide by Caco-2 cells and colonic cells, two known paracellular routes of Pz-peptide, was also evaluated. A simple and sensitive reversed-phase HPLC assay method using UV detection has been developed. The coefficient of variation for all the criteria of validation were less than 15%. The method was, therefore, considered to be sutable for measuring the concentration of Pz-peptide in the biological cells. Pz-peptide was extensively uptaked into hepatocytes. The initial velocity of Pz-peptide uptake assessed from the initial slope of the curve was plotted as Eadie-Hofstee plots. The maximum velocity ($V_{max}$) and the Michaelis constant ($K_m$) were 0.190$\pm$0.020 $nmol/min/10^6$ cells and 12.1$\pm$3.23 $\mu$M, respectively. The permeability-surface area product ($PS{influx}$) was calculated to be 0.0157 ml/min/10^6$ cells. $V_{max}$ and $K_m$ values for Caco-2 cells were calculated to be 6.22$\pm$0.930 pmol/min/10^6$ cells and 82.8$\pm$8.37 $\mu$M, respectively, being comparable with those of colonocytes (6.04$\pm$1.03 pmol/min/10^6$ cells and 87.8$\pm$13.2 $\mu$M, respectively). $PS_{influx}$ values for Caco-2 cells and colonocytes were calculated to be 0.0751 $\mu$l/min/10^6$ cells and 0.0688 $\mu$l/min/10^6$ cells, respectively. The more pronounced uptake of Pz-peptide by hepatocytes, when compared with Caco-2 cells and colonocytes, is probably due to its specific transporter. In conclusion, Pz-peptide, a paracellularly transported pentapeptide in the intestine and ocular epithelia, was uptaked into hepatocytes extensively. Although Pz-peptide is able to be uptaked into the Caco-2 cells and colonocytes, it is less pronounced when compared with hepatocytes. $PS_{influx}$ values of Caco-2 cells and colonocytes for unbound Pz-peptide under linear conditions were less than 0.4% when compared with that of hepatocytes.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.4 s.316
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• pp.28-35
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• 2007

Airbone laser altimeters have been utilized for 3D topographic mapping of the earth, moon, and planets with high resolution and accuracy, which is a rapidly growing remote sensing technique that measures the round-trip time emitted laser pulse to determine the topography. The traveling time from the laser scanner to the Earth's surface and back is directly related to the distance of the sensor to the ground. When there are several objects within the travel path of the laser pulse, the reflected laser pluses are distorted by surface variation within the footprint, generating multiple echoes because each target transforms the emitted pulse. The shapes of the received waveforms also contain important information about surface roughness, slope and reflectivity. Waveform processing algorithms parameterize and model the return signal resulting from the interaction of the transmitted laser pulse with the surface. Each of the multiple targets within the footprint can be identified. Assuming each response is gaussian, returns are modeled as a mixture gaussian distribution. Then, the parameters of the model are estimated by LMS Method or EM algorithm However, each response actually shows the skewness in the right side with the slowly decaying tail. For the application to require more accurate analysis, the tail information is to be quantified by an approach to decompose the tail. One method to handle with this problem is proposed in this study.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.767-776
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• 2014

Changes in climate have largely increased concentrated heavy rainfall, which in turn is causing enormous damages to humans and properties. Floods are one of the most deadly and damaging natural disasters known to mankind. The flood forecasting and warning system concentrates on reducing injuries, deaths, and property damage caused by floods. Therefore, the exact relationship and the spatial variability analysis of hydrometeorological elements and characteristic factors is critical elements to reduce the uncertainty in rainfall-runoff model. In this study, grid resolution depending on the topographic factor in rainfall-runoff models presents how to respond. semi-distribution of rainfall-runoff model using the model GRM simulated and calibrated rainfall-runoff in the Gamcheon and Naeseongcheon watershed. To run the GRM model, input grid data used rainfall (two event), DEM, landuse and soil. This study selected cell size of 500 m(basic), 1 km, 2 km, 5 km, 10 km and 12 km. According to the resolution of each grid, in order to compare simulation results, the runoff hydrograph has been made and the runoff has also been simulated. As a result, runoff volume and peak discharge which simulated cell size of DEM 500 m~12 km were continuously reduced. that results showed decrease tendency. However, input grid data except for DEM have not contributed increase or decrease runoff tendency. These results showed that the more increased cell size of DEM make the more decreased slope value because of the increased horizontal distance.