• Journal of Wetlands Research
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• v.19 no.1
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• pp.132-143
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• 2017

It is essential to obtain periodic sediment discharge data in a river in order to minimize problems that may arise from the erosion, transport, and deposition of sediment. However, it is difficult to estimate sediment discharge by the sediment discharge measurement plan in Korea at present, and empirical fomulas or numerical models are used to replace them. This paper has applied the K-DRUM model, a grid-based rainfall-runoff-sediment model, to estimate sediment discharge and ensure the continuity of the data in the watershed. Discharge and sediment load in 17 watersheds were estimated and the applicability of the model was analyzed through comparisons with measured data. For quantitative evaluation, NSE, PBIAS and RSR items were used, and discharge results reflected the tendency of rainfall and showed high statistical value. In case of sediment discharge, the soil erosion process of the watershed is physically well reflected. When the calibration was performed using the measure data, the applicability seems to be excellent in estimating the continuous sediment discharge data in the real watershed.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.4
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• pp.188-193
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• 1999

Transport of pollutants in aquifer largely depends on groundwater flow which is governed by aquifer hydraulic parameters. Determination of these parameters and associated groundwater modeling become essential for adequate remediation of contaminate groundwater. The objective of this paper is to analyze groundwater flow and determine the optimum hydraulic parameters by performing groundwater modeling based on sensitivity analysis for unconfined sandy gavel aquifer constructed in a laboratory scale under various boundary condition. Results revealed that the simulated drawdown was lower than the observed drawdown irrespective of boundary conditions. and specific yield (S$_{y}$) had less effect on the grondwater flow than permeability (K) in the aquifer. Water balance analysis showed that the measured drawdown in neighboring observation wells during pumping was higher than either simulated or recovered water table. The indicated that a difference might exist in the water tables between aquifer and wells. The difference was investigated by time domain reflectometry (TDR) measurements on water contents in the region of water table and capillary fringe, and explained by a delayed response of water table during gravitational drainage as the water table was lowered as a result of pumping.g.

• Asian Journal of Atmospheric Environment
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• v.4 no.3
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• pp.189-197
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• 2010

An orchestrated attempt was made to analyze samples of bulk and individual particulate matters (PM) collected at the Gosan ground-based station on the west coast of Jeju, Korea. A two-stage filter pack sampler was operated to collect particles in both large (> $1.2\;{\mu}m$) and small size fractions (< $1.2\;{\mu}m$) between the Asian dust (hereafter called "AD") storm event and non-Asian dust period. Elemental components in bulk and individual particles were determined by PIXE and synchrotron XRF analysis systems, respectively. To assess the transport pathways of air parcels and to determine the spatial distribution of PM, the backward trajectories of the Meteorological Data Explorer (Center for Global Environmental Research, 2010) and the NOAA's HYSPLIT dispersion-trajectory models were applied. In line with general expectations, Si and other crustal elements in large size particles showed considerably higher mass loading on AD days in comparison with non-AD days. Computation of the crustal enrichment factors [(Z/Si)$_{particle}$/(Z/Si)$_{desert}$ sand] of elements in large size particles (> $1.2\;{\mu}m$) allowed us to estimate the source profile and chemical aging of AD particles as well as to classify the soil-origin elements. On the basis of a single particle analysis, individual AD particles are classified into three distinct groups (neutralized mineral particles, S-rich mineral particles, and imperfectly neutralized particles).

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.255-263
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• 2012

BACKGROUND: The analysis for the concentration and enantiomeric ratio of OCPs have been performed to confirm the distribution and to emonstrate the pollution characteristics of chiral OCPs in ambient air. METHODS AND RESULTS: In ambient air at coastal and inland sites, concentrations and enantiomer fractions (EFs) of heptachlor (HEPT), eptachlor epoxide (HEPX), trans-chlordane (TC), cis-chlordane (CC), xychlordane (OXY), 2,4'-DDT, 2,4'-DDD with HRGC/HRMS were investigated to understand source and distribution of chiral organochlorine pesticides (OCPs) in ambient air. The mean concentrations of OCPs in ambient air were at the range of 0.027(heptachlor)~1.279 (4,4'-DDT) pg/m3 and 0.0005 (heptachlor)~0.1043 ng/g d.w. (TC), respectively. The mean EFs of OCPs in ambient air were at the range of 0.73 (HEPX)~0.45 (CC). Both preferential depletions of (+) and (-) enantiomer were observed for CC, indicated by EFs either <0.5 or >0.5, while preferential depletions of (-) enantiomer which mean EFs <0.5 were observed for chiral OCPs except TC and MC-5. CONCLUSION: OCPs in ambient air have been distributed from soil, but some of them such as chlordane, DDT etc. might have been introduced by long-range atmospheric transport, considering EFs by chiral analysis and trajectory analysis.

• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.30-37
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• 1995

In the tidal compartment, the hydraulic head is affected by the stage of tidal rivers. For groundwater or construct works, head variation of groundwater should be considered in zone of this aquifer. A numerical analysis is performed which has an 1-dimemsional explicit finite difference scheme to show the head variation of groundwater with tidal stage and hydraulic conductivity, etc. The stability of the numerical scheme is validated by using the analytic solution. The head variation of groundwater is observed for various tidal amplititude and hydraulic conductivity, mean hydraulic gradient and pumping at any point. The range of influence corresponding to the parameters used in this study is about 60m. This value is not beyond a wave length (equation omitted). There was a pumping at a constant rate out of aquifers affected by tide and not affected by tide. Because pumping head in aquifer affected by tide is short, the expense of electric power is economized in this zone. These results are applicable to trace of contaminant transport, efficient operation of groundwater, and examination of the safety and stability of works in the tidal compartment.

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.102-108
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• 2008

In China, energy and environmental problems are becoming serious owing to rapid economic development. Coal is the most problematic energy source because it causes indoor and outdoor air pollution, acid rain, and global warming. One type of clean coal technology that has been developed is the coal-biomass briquette (or bio-briquette, BB) technique. BBs, which are produced from pulverized coal, biomass (typically, agricultural waste), and a sulfur fixation agent (slaked lime, $Ca(OH)_2$) under high pressure without any binder, have a high sulfur-fixation effect. In addition, BB combustion ash, that is, the waste material, can be used as a neutralization agent for acidic soil because of its high alkalinity, which originates from the added slaked lime. In this study, we evaluated the suitability of alternative biomass sources, namely, aquatic plants, as a BB constituent from the perspective of their use as a source of energy. We selected three types of aquatic plants for use in BB preparation and compared the fuel, handling, and environmental characteristics of the new BBs with those of conventional BBs. Our results showed that air-dried aquatic plants had a higher calorific value, which was in proportion to their carbon content, than agricultural waste biomass; the compressive strength of the new BBs, which depends on the lignin content of the biomass, was high enough to bear long-range intracontinental transport in China; and the new BBs had the same emission control capacity as the conventional BBs.

• Geomechanics and Engineering
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• v.28 no.4
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• pp.397-404
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• 2022

Accurate prediction of the undrained shaft resistance is essential for robust design of bored piles in undrained condition. The undrained shaft resistance is calculated using the undrained adhesion factor multiplied by the undrained cohesion of the soil. However, the available correlations to predict the undrained adhesion factor have been developed using simple regression techniques and the accuracy of these correlations has not been thoroughly assessed in previous studies. The lack of the assessment of these correlations made it difficult for geotechnical engineers to select the most accurate correlation in routine designs. Furthermore, limited attempts have been made in previous studies to use advanced data mining techniques to develop simple and accurate correlation to predict the undrained adhesion factor. This research, therefore, has been conducted to fill these gaps in knowledge by developing novel and robust correlation to predict the undrained adhesion factor. The development of the new correlation has been conducted using the multi-objective evolutionary polynomial regression analysis. The new correlation outperformed the available empirical correlations, where the new correlation scored lower mean absolute error, mean square error, root mean square error and standard deviation of measured to predicted adhesion factor, and higher mean, a20-index and coefficient of correlation. The correlation also successfully showed the influence of the undrained cohesion and the effective stress on the adhesion factor. Hence, the new correlation enhances the design accuracy and can be used by practitioner geotechnical engineers to ensure optimized designs of bored piles in undrained conditions.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.E2
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• pp.85-96
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• 2000

The concentrations of Pb, Mn, Al and Na were measured from a total of 26 snow samples collected from a 1.5-m deep snow pit in Livingston Island, South Shetland Islands, at the northern tip of the Antarctic Peninsula. Ore sampling location is great concern, because of its proximity to the southern extremity of south America, a candidate for the source regions of pollutant aerosols entering Antarctica. The mean concentrations of Pb and Mn were found to be 4.97 pg g(sup)-1 and 20.6 pgg(sup)-1, respectively. These concentrations levels are similar to those reported for recent snow at other Antarctic sites with pronounced spring maxima for both metals. Contributions form natural sources are estimated to be minor (∼16%) for Pb. For Mn, on the other hand, contribution from rock and soil dusts is found to be very important. Excess Pb over Pb from natural sources is likely to be anthropogenic, especially from South Americal. Our results show that yearly Pb fallout flux is much greater in Antarctic coastal areas than at other Antarctic locations far from the coast , indicating that the transport and deposition patterns of pollutant aerosols are not simple is Antarctica. It is also suggested that the recycling of anthropogenic Pb in seawater to the atmosphere could significantly contribute to the Pb fallout flux in the Antarctic coastal regions.

• Asian Journal of Atmospheric Environment
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• v.6 no.1
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• pp.14-22
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• 2012

This paper is focused on the comprehensive and detailed interpretation for the chemical transformation of individual Asian dust (hereafter called "AD") particles during long-range transport from source regions to receptor area. A multi-stage particle sampler was operated at a ground-based site in Taean, Korea directly exposed to the outflow of air masses from China during AD period in April 2003. Both quantitative and qualitative analyses for size-classified individual particles were carried out by a microbeam X-ray fluorescence (XRF) method and a microbeam Particle Induced X-ray Emission (micro-PIXE), respectively. Among major characteristic elements, the elemental masses of soil derived components, sulfur, and chloride varied as a function of particle size showing the monomodal maximum with a steeply increasing at 3.3-4.7 ${\mu}m$ particle size. Although the details on chemical composition of AD particle collected on a straight line from source area to our ground-based site are needed, a large amount of Cl coexisted in and/or on AD particles suggests that AD particles collected in the present study might be actively engaged in chemical transformation by sea-salt and other Cl containing pollutants emitted from the China's domestic sources. Through the statistical analyses it was possible to classify individual AD particles into six distinct groups. The internally mixed AD particles with Cl, which has various sources (e.g., sea-salt, coal combustion origin HCl, gaseous HCl derived from the adsorption of acids to sea-salt, and Cl containing man-made particles) were thoroughly fractionated by the elemental spectra drivened by the double detector system of micro-PIXE.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.246-246
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• 2017

Salinity inhibits plant growth and restricts the efficiency of arbuscular mycorrhizal fungi. The selective uptake of nutrients from the soil and their effective transport to host roots make it essential for plant growth and development under salt stress. AMF spore associated bacteria shown to improve mycorrhizal efficiency under stress. Thus, this study aimed to understand the co-inoculation efficiency of AMF and SAB on maize growth and ion homeostasis under salt stress. Two AMF strains and one SAB were inoculated with maize either alone or in combination with one another. The results of our study showed that AMF and SAB co-inoculation significantly improved dry weight and nutrient uptake of maize under salt stress. Co-inoculation significantly reduced proline accumulation in shoots and Na+ accumulation in roots. Co-inoculation treatment also exhibited the high K+/Na+ ratios in roots at 25 mM NaCl. Mycorrhizal colonization showed positive influence for regulation of ZmAKT2, ZmSOS1 and ZmSKOR gene expressions, contributing to K+ and Na+ ion homeostasis. CLSM view showed that SAB were able move and localize into inter and intra cellular spaces of maize roots. In addition, CLSM view of AMF spores showed that gfp-tagged SAB also associated on the spore outer hyaline layer.