• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.785-791
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• 2009

Using artificial rainfall simulator, the soil loss, which is deemed as the most cause of muddy water problem among Non-point source (NPS) pollutant, was studied by the analysis of direct runoff, groundwater discharge, and soil water storage properties concerned with rainfall intensity, slope of area, and land cover. The direct runoff showed increasing tendency in both straw covered and bared soil as slope increases from 5% to 20%. The direct runoff volume from straw covered surface were much lower than bared surface. The infiltration capacity of straw covered surface increased, because the surface sealing by fine material of soil surface didn't occur due to the straw covering. Under the same rainfall intensity and slope condition, 2.4~8.2 times of sediment yield were occurred from bared surface more than straw covered surface. The volume of infiltration increased due to straw cover and the direct runoff flow decreased with decrease of tractive force in surface. To understand the relationship of the rate of direct runoff, groundwater discharge, and soil water storage by the rainfall intensity, slope, and land cover, the statistical test was performed. It shows good relationship between most of factors, except between the rate of groundwater storage and rainfall intensity.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1161-1166
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• 2008

The objective of this research was to investigate the enhancement of heat transfer by mesh in water/air direct contact air conditioning system. Mesh is inserted as a turbulent promoter in front of the water injection nozzle. The heat transfer characteristics with and without mesh and the effect of the number of inserted mesh and mesh porosity size have been studied experimentally. Inserted mesh improves heat transfer efficiency compared to non-inserted mesh system and heat transfer efficiency increased as the number of mesh is increased. Meanwhile, heat transfer efficiency decreased as the porosity of the mesh is increased. With inserted mesh, inlet and outlet temperature difference of air increased more than 50%. Heat exchange time of water/air to reach the 100% humidity decreased less than 30%. This result shows inserted mesh can enhance the performance of the water/air direct contact air conditioning system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.75-80
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• 2008

The objective of this research was to investigate the enhancement of heat transfer by mesh in water/air direct contact air conditioning system. Mesh is inserted as a turbulent promoter in front of the water injection nozzle. The heat transfer characteristics with and without mesh and the effect of the number of inserted mesh and mesh porosity size have been studied experimentally. Inserted mesh improves heat transfer efficiency compared to non~inserted mesh system and heat transfer efficiency increased as the number of mesh is increased. Meanwhile, heat transfer efficiency decreased as the porosity of the mesh is increased. With inserted mesh, inlet and outlet temperature difference of air increased more than 50%. Heat exchange time of water/air to reach the 100% humidity decreased less than 30%. This result shows inserted mesh can enhance the performance of the water/air direct contact air conditioning system.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.984-993
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• 2009

There have been growing concerns of algal growth at Daecheong reservoir due to eutrophication with excess nutrient inflow. Rainfall-driven runoff and pollutant from watershed are responsible for eutrophication of the Daecheong reservoir. In this study, two subwatersheds of the Daecheong reservoir were selected and water quality characteristics were analyzed. The L-THIA ArcView GIS model was used for evaluation of direct runoff and water quality. The $R^2$ and the EI value for direct runoff were 0.95 and 0.93 at Wol-oe watershed and were 0.81, 0.71 at An-nae watershed, respectively. The $R^2$ for SS, T-P were 0.53, 0.95 at Wol-oe watershed and 0.89, 0.89 at An-nae watershed, respectively. It has been proven that the L-THIA ArcView GIS model could be used for evaluating direct runoff and pollutant load from the watershed with reasonable accuracies.

• The KSFM Journal of Fluid Machinery
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• v.11 no.6
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• pp.38-45
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• 2008

Development of high efficiency turbine with good performance is one of the main topics in the field of developing wave energy converter. For the development and improvement of the turbine performance, the effect of wave condition on the turbine performance should be considered in detail. Also, water depth is an important factor because incident wave power to the turbine is considerably influenced by the wave particle amplitude of motion and the amplitude is closely related with the water depth. Therefore, in this study, the effect of water depth on the performance of a direct drive turbine(DDT) for wave energy converter is investigated using the DDT which is installed in two types of wave channel. The experimental results show that the DDT captures more wave energy under the condition of relatively shallow water depth. When the water depth is shallow, the horizontal water particle amplitude of motion becomes wider and thus, the water power toward the turbine becomes larger.

• International Journal of High-Rise Buildings
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• v.12 no.4
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• pp.335-341
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• 2023

This study proposes a novel rotary direct evaporative cooler and investigates the potential of a moisture-wicking fabric as a cooling pad for the proposed evaporative cooler. The rotary direct evaporative cooler rotates the cooling pad to reduce the water and energy consumption of the pump compared to those of existing direct evaporative coolers. A moisture-wicking fabric is considered as the material of the cooling pad, because of its high moisture-wicking property, enhancing water evaporation. Experiments are performed under various inlet air conditions while measuring the air temperature, relative humidity, air velocity, and differential pressure. The evaporative cooling efficiency and impacts of the inlet air temperature and air velocity on the cooling performance are also evaluated. The results demonstrate the potential of the moisture-wicking fabric as cooling pad of direct evaporative cooler.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1171-1178
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• 1992

An experiment was performed to describe the heat and mass transfer occurring between hot waste gas and cold water through direct contact in a direct contact heat exchanger. This model was then used to obtain an equation of overall heat transfer coefficent based on heat exchanger volume. The diffusion heat transfer rate is 2-3 times larger than the convection heat transfer rate as results of condensation of the water vapor contained in the waste gas. The boiler efficiency increases over 10%.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.507-515
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• 2002

Remote Sensing Monitoring and Loss Estimated System of Flood Disaster based on GIS is an integrated system comprised flood disaster information receiving and collection, flood disaster simulation, and flood disaster estimation. When the system receives and collects remote sensing monitoring and conventional investigation information, the distributional features of flood disaster on space and time is obtained by means of image processing and information fusion. The economic loss of flood disaster can be classified into two pus: direct economic loss and indirect economic loss. The estimation of direct economic loss applies macroscopic economic analysis methods, i.e. applying Product (Industry and Agriculture Gross Product or Gross Domestic Product - GDP) or Unit Synthetic Economic Loss Index, direct economic loss can be estimated. Estimating indirect economic loss applies reduction coefficient methods with direct economic loss. The system can real-timely ascertains flood disaster and estimates flood Loss, so that the science basis fur decision-making of flood control and relieving disaster may be provided.

• Coupled systems mechanics
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• v.4 no.4
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• pp.317-336
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• 2015

The present paper deals with the analysis of water tank with elastic separator wall. Both fluid and structure are discretized and modeled by eight node-elements. In the governing equations, pressure for the fluid domain and displacement for the separator wall are considered as nodal variables. A method namely, direct coupled for the analysis of water tank has been carried out in this study. In direct coupled approach, the solution of the fluid-structure system is accomplished by considering these as a single system. The hydrodynamic pressure on tank wall is presented for different lengths of tank. The results show that the magnitude of hydrodynamic pressure is quite large when the distances between the separator wall and tank wall are relatively closer and this is due to higher rotating tendency of fluid and the higher sloshed displacement at free surface.

• Journal of Korean Society on Water Environment
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• v.32 no.1
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• pp.108-114
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• 2016

Sediment-laden water leads to water quality degradation in streams; therefore, best management practices must be implemented in the source area to control nonpoint source pollution. Field monitoring was implemented to measure precipitation, direct runoff, and sediment concentrations at a control plot and straw-applied plot to examine the effect on sediment reduction in this study. A hydrology model, which employs Curve Number (CN) to estimate direct runoff and the Universal Soil Loss Equation to estimate soil loss, was selected. Twenty-five storm events from October 2010 to July 2012 were observed at the control plot, and 14 storm events from April 2011 to July 2011 at the straw-applied plot. CN was calibrated for direct runoff, and the Nash-Sutcliffe efficiency and coefficient of determination were 0.66 and 0.68 at the control plot. Direct runoff at the straw-applied plot was calibrated using the percentage direct runoff reduction. The estimated reduction in sediment load by direct runoff reduction calibration alone was acceptable. Therefore, direct runoff-sediment load behaviors in a hydrology model should be considered to estimate sediment load and the reduction thereof.