• 한국농공학회지
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• 제42권3호
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• pp.56-65
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• 2000

The characteristics of agricultural water rights were examined for the national rivers in Korea. We suggest that the national rivers could according to the actual management organization of agricultural water right be categorized into national management rivers KOWACO(Korea Agrcultural & Rural Infrastructure COrporation) management river. The agricultural water right between the national and KOWACO management rivers have different characteristics for irrigation period permit procedure water charge and type of water right. The agricultural water rights are granted in the natural discharge less than reference droughty discharge for most of national management rivers and in the developed discharge for the KOWACO and KARICO management rivers. The current system of agricultural water rights is complicated inconsistent and incapable of coping with unusual drought and therefore it needs to be improved.

• 한국환경과학회지
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• 제3권4호
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• pp.317-332
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• 1994

Based on the Results of Marine Meteorological and Oceanographical Observations (1966 ~ 1987), oceanographic conditions of the Japan Sea in winter was studied in relation to the Japan Sea Proper Water (JSPW). The mean and dispersion of the deep water above 1000 m depth are 0.26$\pm$0.2$^{\circ}C$ in temperature and 5.1$\pm$0.25 ml/h in oxygen. The mean and dispersion of the bottom water below 1000m depth are 0.07$\pm$$0.04^{\circ}C$ in temperature and 5.1$\pm$0.15ml/1 in oxygen. The distributions of the temperature and dissolved oxygen in the deep water above 1000m depth are ranged wider than 각one of the bottom water below 1000m depth in T-S and T-$ extrm{O}_2$ diagrams. The bottom water are showed more homogeneous and smaller variations than the deep water in the characteristics of water mass. The deep water above 1000m depth is active in contact with the atmosphere. The JSPW similar to the above characteristics is showed in the open ocean of the north of $40^{\circ}$30""N, west of $138^{\circ}$E. Therefore, the deep water is formed probably by the open-ocean convection.tion.

• 전기학회논문지
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• 제59권9호
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• pp.1632-1637
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• 2010

A micro-water-nozzle, as one of a cooling means of micro-electronic devices, has been proposed and investigated. The I-V characteristics of the micro-water-nozzle and effect of applied voltage on the meniscus formation and deformation and ejection processes of de-ionized water on the micro-water-nozzle tip have been investigated. The water ejection processes, such as a drop formation, a drop deformation, a dripping, a cone jet, and an atomization, were taken place on the micro-water-nozzle tip by the electrohydrodynamic forces acted by the DC and AC high voltages applied on the meniscus of the micro-water-nozzle tip. The I-V characteristics of the micro-water-nozzle-to-plate electrode system were different from that of the same metal-point electrode system, due to the meniscus formation and water droplet ejection at the nozzle tip. The positive and negative DC and AC high voltages showed the water droplets ejection, the ejection rates of 1.8, 1.5 and 1.2 g/h respectively, which, however, showed that the proposed micro-water-nozzle-to-plate electrode system could be used as one of an effective pumping means.

• 한국물환경학회지
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• 제23권4호
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• pp.527-534
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• 2007

To operate scientifical and integrated management of water resources, it needs to identify clearly the quantitative variation and moving pathway of water resources in a basin. Moreover, it needs to also estimate more precisely the amount of runoff generating from the precipitation. Thus, in this study, to carry out more reliable hydrologic analyses, the runoff characteristics according to detailed runoff components and water balance in a basin are analyzed. As a result of yearly water balance analyses, during the period of drought year, the loss is bigger than that of 6-year mean loss and the return flow of groundwater is the most dominant component of runoff. During the period of flood year, the loss is smaller about 4% than that of 6-year mean loss and the subsurface water is the most dominant component of runoff. The loss due to the interception and evapotranspiration for 6-year mean loss is about 53% of the total rainfall, the mean runoff ratio is about 27% and the baseflow is about 22%.

• 한국농공학회논문집
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• 제58권3호
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• pp.47-56
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• 2016

Superabsorbent Polymers (SAPs) are hydrophilic synthetic polymers which could absorb water by hundreds of their own weight. They are used for multiple purpose including hygienic goods, soil conditioners, and hospital supplies. It is necessary to investigate the standard of their use including the amendment rate for soil application in agricultural fields. It is also important to understand their effects on the soil water content and engineering characteristics. The objective of this study is to find the water absorbing capacity and reusability of SAPs, and the characteristics of water release and effect of them on soil water content and engineering characteristics. In the result, SAPs per unit weight (1 g) used for this research could absorb about 200 g of water in max. The water absorbing capacity decreased after SAPs were used repeatedly. Released water of SAPs could provide the soils with about 9 % of the soil water content. Soil water content increased with decreasing distance from the SAPs. The distance of release was spreaded out with increasing water absorbed of SAPs. Finally, when a drainage and the capacity of soil water content were considered, it is recommended to amend the SAPs with soil by less than 0.25 %.

• 한국환경과학회지
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• 제9권5호
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• pp.423-428
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• 2000

The characteristics of Far-infrared rays mineral water(FIR water) have been compared to the tap water by means of relationship between FIR water and Nuclear Magnetic Resonance spectroscopy(NMR), FIR water and thermography FIR water and velocity of blood FIR-water and pH, FIR water and dissolved oxygen(DO), FIR water and Oxidation-Reduction Potential(ORP) using the development FIR water purification of grand prix system. From the experimental result are quite satisfactory when compared with the tap water. Also the FIR water were evaluated to see if those are tasty and healthy using the Hashimoto's Mineral Balance Index. As a result FIR-water was found as tasty and healthy.

• Geomechanics and Engineering
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• 제14권5호
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• pp.407-419
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• 2018

In order to investigate flow characteristics after water inrush from the working face in process of karst tunnel construction, numerical calculation for two class case studies of water inrush is carried out by using the FLUENT software on the background of Qiyueshan tunnel. For each class water inrush from the tunnel face, five cases under different water-inrush velocity are simulated and researched. Three probing lines are selected respectively in the left tunnel, cross passage, right tunnel and in the height direction of the tunnel centerline. The variation characteristics of velocity and pressure on each probing line under the five water-inrush velocities are analyzed. As for the selected four groups probing lines in the tunnels, the change rules of velocity and pressure on each group probing lines under the same water-inrush velocity are discussed. Finally, the water flow characteristics after inrush from the tunnel face are summarized by comparing the case studies. The results indicate that: (1) The velocity and pressure change greatly at the intersection area of the cross passage and the tunnels. (2) The velocity nearby the tunnel side wall is the minimum, while it is the maximum in the middle position. (3) The pressure value of every cross section in the tunnels is basically fixed. (4) As water-inrush velocity increases, the flow velocity and pressure in the tunnels also increase. The former is approximately proportional to their respective water-inrush velocity, while the latter is not. The research results provide a theoretical basis for making scientific and rational escape routes.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.450-465
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• 2021

In this study, an attempt has been made to investigate the water-entry characteristics of the high-speed parallel projectile numerically. The shear stress transport k-𝜔 turbulence model and the Zwart-Gerber-Belamri cavitation model based on the Reynolds-Averaged Navier-Stokes method were used. The grid independent inspection and grid convergence index is carried out and verified. The influences of the parallel water-entry on flow filed characteristics, trajectory stability and drag reduction performance for different values of initial water-entry speed (𝜈₀ = 280 m/s, 340 m/s, 400 m/s) and clearance between the parallel projectiles (L_p = 0.5D, 1.0D, 2.0D, 3.0D) are presented and analyzed in detail. Under the condition of the parallel water-entry, it can be found that due to the intense interference between the parallel projectiles, the distribution of cavity is non-uniform and part of the projectile is exposed to water, resulting in the destruction of the cavity structure and the decline of trajectory stability. In addition, the parallel projectile suffers more severe lateral force that separates the two projectiles. The drag reduction performance is impacted and the velocity attenuation is accelerated as the clearance between the parallel projectiles reduces.

• 연구논문집
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• 통권25호
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• pp.129-135
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• 1995

This study discribes characteristics of water spray for extinguishment of gasoline pool fire. Experiments are carried out for the gasoline pool fire in a small tank with a diameter of 150mm and a height of 8mm. Droplet size, spray pressure, amount of water which reaches the flame base and velocity of water spray are measured to find extinguishment conditions and air entrainment due to the water spray is visualized. Critical conditions of water spray for extinguishment of gasoline pool fire is quantitatively shown.

• 한국환경과학회지
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• 제20권3호
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• pp.373-384
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• 2011

This study aims at the examination of the relative characteristics of discharge and water quality in river basins using statistical methods. For it, water quality and discharge data was collected in observed stations of Nakdong river and carried out correlation analysis, regression analysis, factor analysis and cluster analysis. And it was investigated the applicability of water quality prediction using Nearest-neighbor method. As a result, it grasped a trenditional characteristics and mutual relations between discharge an water quality data. Therefore, this results were suggested the comprehensive data and methods for a management of water quality, effective operation and policy development in Nakdong river basin.