• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.875-889
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• 2021

This study compares and analyzes the Soil and Water Assessment Tool (SWAT) and Terra MODIS (Moderate Resolution Imaging Spectroradiometer) as coniferous, deciduous and mixed forest with Yongdam Dam upstream (904.4 km²). The hydrologic evaluation period was set to 10 years from 2010 to 2019, and the applicability of the 8-day MOD15A2 Leaf Area Index (LAI) data, 3 TDR (Time Domain Reflectometry) (GB, JC, CC), and 1 Flux Tower (DU) evaporation volume (YDD) data was simulated. As a result, the R² of coniferous forest, deciduous forest and mixed forest are 0.95, 0.89, 0.90, soil moisture and evaportranspiration stations R² were analyzed at 0.50 to 0.55 and 0.51, respectively, with R² at 0.74, RMSE 2.75 mm/day, NSE 0.70 and PBIAS 14.3% for Yongdam inflow. Based on the calibrated and validated watersheds, the annual average evaportranspiration was calculated as coniferous 469.7 mm, deciduous 501. mm and 511.5 mm mixed forest, total runoff were estimated at coniferous 909.8 mm, deciduous 860.6 mm and 864.2 mm mixed forest. In the case of annual average evaportranspiration, it was evaluated that deciduous were high, but in the case of streamflow, it was evaluated that coniferous were high. Unlike other hydrologic with similar patterns throughout the year, the average annual evapotranspiration was about 7% higher than coniferous due to the higher evapotranspiration of deciduous with high leaf area index in summer and fall. In addition, deciduous were 9% and 6% higher for surface runoff and lateral flow, but the groundwater of coniferous was 77% higher. Therefore, it was confirmed that the total runoff was in order of coniferous, mixed forest, and deciduous.

• Journal of Korean Neurosurgical Society
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• v.29 no.12
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• pp.1555-1562
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• 2000

Objects : Surgical management of the distal anterior cerebral artery(DACA) aneurysms presents several unique problems to surgeons, such as difficulty in early identification of parent arteries, high incidence of rebleeding and premature rupture, and requirement of unfamiliar approach other than conventional frontotemporal craniotomy. Therefore, preoperative anatomical knowledge of anterior interhemispheric fissure and entry point of dissection is prerequisite. Authors utilized a frontobasal approach for DACA aneurysms by using consistent external landmark for guidance to the deep structure. Materials and Methods : From Nov. 1995 to Jun. 1999, a surgical clipping of DACA aneurysms was carried out in 9 patients among a total 131 patients with intracranial aneurysms. In each case, the clinical and aneurysmal features were carefully reviewed through the angiograms, medical records, and intraoperative findings. Results : The incidence of DACA aneurysms was 6.9% from our series. All cases were arisen from juxtacallosal por-tion ; 6 cases from pericallosal-callosomarginal(PC-CM) junction and 3 from pericallosal-frontopolar(PC-FP) junction. Associated vascular anomalies were noted in 3 cases and multiple aneurysms in 3 cases, respectively. The preoperative clinical grades were generally poor. An early surgery was performed in 7 cases and frontobasal interhemispheric approaches in 7 cases. Postoperatively, two patients died of complications ; one delayed ischemic vasospasm and one aspiration pneumonia but remaining patients recovered well. Conclusion : The frontobasal interhemispheric approach was useful for DACA aneurysms in early surgery. Division of superior sagittal sinus(SSS) enabled a minimal retraction of brain on both sides, and prevention of intraoperative rupture was possible. Authors suggest the frontopolar(first frontal bridging) vein as a constant external landmark for approaching the genu of the corpus callosum and juxtacallosal DACA aneurysms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.4
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• pp.23-32
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• 1988

The rates of infiltration contributed to the flow fo water in an unconfined aquifer under the partially penetrated stream at an ungaged station and the corresponding base flow in channel are coupled by using the hydraulic and/or hydrologic characteristics obtained from the geomorphologic and soil maps. For the determination of groundwater flow, the linearized model which is originally Boussinesq's nonlinear equation is applied in this study. Also, a stream flow routing model for base flow in channel is based on a simplification of the Saint-venant. The distributed runoff model with piecewise spatial uniformity is presented for obtaining its solution based on a finite difference technique of the kinematic wave equations. The method developed in this study was tested to the Bocheong watershed(area : $475.5km^2$) of the natural stream basin which is one of tributaries in Geum River basin in Korea. As a result, it is suggested that the rationality of hydro-graph separation according to a wide variability in hydrogeologic properties be worked out as developing the physically based subsurface model. The results of the present model are shown to be possible to simulate a base flow due to an arbitrary rate of infiltration for ungaged basins.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.19-32
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• 2007

In Korea, there have been various methods of estimating groundwater recharge which generally can be subdivided into three types: baseflow separation method by means of groundwater recession curve, water budget analysis based on lumped conceptual model in watershed, and water table fluctuation method (WTF) by using the data from groundwater monitoring wells. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, so these methods have various limits to deal with these characteristics. To overcome these limitations, we present a new method of estimating recharge based on water balance components from the SWAT-MODFLOW which is an integrated surface-ground water model. Groundwater levels in the interest area close to the stream have dynamics similar to stream flow, whereas levels further upslope respond to precipitation with a delay. As these behaviours are related to the physical process of recharge, it is needed to account for the time delay in aquifer recharge once the water exits the soil profile to represent these features. In SWAT, a single linear reservoir storage module with an exponential decay weighting function is used to compute the recharge from soil to aquifer on a given day. However, this module has some limitations expressing recharge variation when the delay time is too long and transient recharge trend does not match to the groundwater table time series, the multi-reservoir storage routing module which represents more realistic time delay through vadose zone is newly suggested in this study. In this module, the parameter related to the delay time should be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater table with observed one as well as to compare simulated watershed runoff with observed one. This method is applied to Mihocheon watershed in Korea for the purpose of testing the procedure of proper estimation of spatio-temporal groundwater recharge distribution. As the newly suggested method of estimating recharge has the advantages of effectiveness of watershed model as well as the accuracy of WTF method, the estimated daily recharge rate would be an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers and aquifers.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.35-43
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• 2015

A method is proposed to estimate groundwater usage for water curtain cultivation (WCC) using a rating curve, and it is applied to field measurements of groundwater discharge used for WCC in Wangjeon-ri, Nonsan. During the winter season, the hydraulic components of irrigation ditches in the study area consist mainly of direct run-off and groundwater discharged from nearby pumping wells. Changes in stage of the ditches were monitored, and a baseflow separation method was applied to remove increments in stage due to direct run-off. The resulting records of stage were translated to groundwater discharge by applying the-stage-discharge relation. The estimated average groundwater discharge for the WCC in Wangjeon-ri was 10,900 m³/d or 420 m³/d/ha when the estimation is normalized by the total area for WCC facilities of this region. Applying this estimation (420 m³/d/ha) to the entire area of the WCC in Korea (10,746 ha),and considering the number of pumping days for the WCC (120 days/year), the total ground water usage for the WCC nation-wide is estimated to be 0.54 billion m³. This is equivalent to 32% of the total groundwater discharge for agricultural use in Korea (1.7 billon m³).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.173-182
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• 1993

This paper presents an algorithm to derive the representative unit hydrograph for the real environment of a watershed. For a given watershed, the conventional methods give several different unit hydrographs by storm events. In this study the LP model is somewhat modified based on the previous study by Mays et also as follows: the objective function is designed to minimize the sum of weighted residuals. An additional constraint of moving average is added to prevent the unit hydrograph from the occurence of oscillation which was not active in Mays's paper. Configuration of rainfall matrix was improved to reduce its dimension in accordance with Diskin's review point. In spite of the superiority of LP approach in terms of representativeness, all the methods were very sensitive to the validity of baseflow separation and rainfall-loss. Several methods of the separations for rainfall excesses and direct runoffs were applied and no preferred methods were identified. This is the matter of judgement considering catchment and rainfall characteristics. This algorithm was applied to a real watershed of the Wi stream in the Nak-dong river. Compared with the IHP results by conventional methods, this optimized representative unit hydrograph demonstrated relatively smaller and shorter values in terms of the peak discharge and the basin lag respectively, and the oscillation of its falling limb successfully eliminated owing to the additional constraints of moving averages.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.67-78
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• 2005

Riverbank filtration has been used in advanced countries for 150 years. In Korea, investigations for producing riverbank filtrate started in the Han River, Nakdong River, Geum River, Yeongsan River and Seomjin River basins in the 1990s. The lower part of the Nakdong River has a poorer water quality than the upper part of the river. A water balance analysis and groundwater flow modeling were conducted for the riverbanks of the Nakdong River in Daesan-Myeon, Changwon City. The results of the water balance analysis revealed the groundwater infiltration rate into the aquifer to be 245.26 mm/year (19.68% of the average annual precipitation, 1,251.32 mm). Direct runoff accounts for 153.49 mm/year, evapotranspiration is 723.95 mm/year and baseflow is 127.63 mm/year. According to the groundwater flow modeling, 65% of the total inflow to the pumping wells originates from the Nakdong River, 13% originates from the aquifer in the rectilinear direction, and 22% originates from the aquifer in the parallel direction. The particle tracking model shows that a particle moving from the river toward the pumping wells travels 100 m in 50 days and a particle from the aquifer toward the pumping wells travels 100 m in 100 days.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.403-403
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• 2021

비점오염물질은 강우에 의해 유출되며 계절적, 자연적 편차가 크게 나타나고, 오염원이 광범위하게 산재하고 있어 오염물질의 발생량과 부하량의 관리가 쉽지 않다. 따라서 비점오염원 관리지역은 오염물질이 하천에 미치는 수질 특성을 파악하는 것이 중요하다. 그러나 수질항목만으로 하천의 수질 특성을 파악하기에는 어려움이 있으며, 수질 특성을 파악하기 위해 다양한 분석방법이 필요하다. 본 연구에서는 비점오염원 관리지역 중 골지천 유역의 수질 특성을 파악하기 위해 통계분석 기법을 활용하여 수질항목간의 상관관계를 분석하고자 하였다. 2017년부터 2019년까지 골지천 유역 내 5개 지점에 대하여 비강우시 23회, 강우시 지점별 173회~196회의 모니터링 결과를 이용하였으며, EC, 탁도, BOD₅, SS, T-N, T-P, TOC의 수질항목을 이용하여 Pearson 상관관계 분석을 실시하였다. 상관관계 분석 결과 비강우시 분석 결과 EC는 -0.06~-0.32, T-N은 0.19~0.37로 낮은 상관성을 갖는 것으로 나타났으며, EC와 T-N을 제외한 탁도와 BOD₅, SS, T-P, TOC의 경우 서로 0.6 이상의 상관성을 갖는 것으로 나타났다. 특히, 탁도와 SS, T-P, T-P와 TOC는 0.9 이상의 높은 상관성을 갖는 것으로 나타났다. 강우시 분석 결과 EC는 비강우시와 유사하게 -0.07~-0.24로 낮은 상관성을 갖는 것으로 나타났으며, TOC를 제외한 탁도, BOD₅, SS, T-N, T-P의 경우 서로 0.6 이상의 상관성을 갖는 것으로 나타났다. TOC의 경우 BOD₅, SS와 0.6 이상의 상관성을 갖는 반면 탁도, T-N, T-P와는 0.45, 0.44, 0.57로 다른 항목에 비해 다소 낮은 상관성을 갖는 것으로 나타났다. 비강우시 T-N은 기저 유출에 의한 영향으로 높은 농도를 나타내 다른 항목에 비해 상관성이 낮은 것으로 나타났으며, 강우시에는 비점오염물질의 유입으로 인하여 모든 항목에서 비슷한 상관성을 보이는 것으로 나타났다. 본 연구 결과 탁도와 SS, T-P의 상관성이 비강우시 0.93, 강우시 0.78로 상당히 높은 것으로 나타나, 탁도를 측정하여 SS와 T-P로 환산하여 측정하는 방법에 대한 기초자료로 활용될 수 있을 것으로 판단된다. 그러나 연구 유역의 지형적 특성이 배제되었기 때문에 추후에 이를 반영한 연구가 필요할 것으로 판단된다.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.376-384
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• 2009

This research has microstructure observation to find tissue damage mechanism and radio-protection effect on mouse kidney tissue. The result observation of a Light Microscope(LM); The kidney tissue after 5Gy irradiation observed a glomerulus atrophy, also crack distance to base membrane of a convoluted tubules. The kidney tissue after 10Gy irradiation observed out flow cytoplasm to membrane break of a convoluted tubules. The result observation of a Transmission Electron Microscope(TEM); The kidney tissue of after 5Gy irradiation has to breaking a inside cristae and membrane of mitochondria, also show definite damage of nucleus membrane. 10Gy irradiation has all the more damage a base membrane and thickness of lysosome. However, Propolis eating groups observed normal to nucleus membrane and small body of intracellular. therefore We considered "Propolis" as make radio protection function to kidney tissue of the greater part.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.525-533
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• 2012

Snowmelt from seasonal snow covers can be significant in many environments of northern and alpine areas. Water flow and chemical transport resulting from snowmelt have been studied for an understanding of contributions to watersheds or catchments. A Mobile-Immobile water Model (MIM) was developed to describe the movement of ionic tracers through a snowpack by Lee et al. (2008a) and Lee et al. (2008b). To validate the model used in the studies, mass balance calculations of the model were conducted and comparisons were made between model results and analytical solutions in this work. Mass balance was calculated based on the fact that change in total mass within a snowpack with time is equal to sum of any change in the flux of water or ionic tracers into and out of the snowpack. Calculations of both water and ionic mass show almost perfect agreement between changes of two water and solute mass fluxes. Comparisons between model results and analytical solutions including wave velocity and effective saturation show almost perfect agreement.