• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.17-24
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• 2005

Korean pine (Pinus koraiensis Sieb.et Zucc.) boards of 30 mm thickness were treated by steaming and four different drying methods. Small specimens were taken from the sapwoods of the treated boards and their longitudinal liquid permeability was measured according to Darcy's law. The specimens were also extracted with alcohol and aceton solutions to examine the mechanism of liquid flow in wood. It was observed that specific permeability drastically decreases with measurement time, resulting in violation of Darcy's law. It may be due to that air bubbles formed under vacuum block flow paths in resin canals. The average specific permeabilities of non-extracted and extracted specimens are different from one treatment to another. It is supposed that the properties of residual resin in resin canals change depending on the conditions of treatments. Anatomical examination was conducted with a scanning electron microscope.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1469-1473
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• 2004

Non-Darcy흐름에 따른 호안제체의 흐름과 배수갑문을 통한 유출입 특성을 고려한 체절구간의 수리특성분석 도형에 의한 해석결과는 실측자료와 비교적 잘 일치하여 개발된 모형의 적용성이 있음을 보여주었다. 실측치와 비교한 계산결과는 본간(1958) 식에 의한 계산이 나(1987)에 의한 방법보다 비교적 정확하게 계산할 수 있음을 보여주었다. 아울러 완전 또는 불완전 월류의 구분이 없이 잠수도에 의한 계산을 통해서 하나의 유량계수 관계곡선을 사용하여 간편하게 사용할 수 있는 나 식의 사용성을 보여 주었다. 본간 식과 나 식에 의한 계산 값이 실측치보다는 유출입 특성이 크게 나타나고 있는 것으로 나타났다. 따라서 현장에서의 체절구간의 불규칙적인 단면 양상을 감안한 유량계수의 조정이 필요할 것으로 판단된다. 일반적으로 체절구간의 수리특성의 분석을 위해서 제체구간 유량의 고려는 Darcy 흐름에 기초하여 분석한 것이 지금까지의 분석이다. 제체를 통과는 유량과 개방구간을 통과하는 유량의 비가 체절구간이 좁을수록 크게 나타나 제체의 정확한 유출임 특성을 고려한 체절구간의 수리특성을 분석해야할 필요가 있음을 확인하였다.

• Journal of Korea Water Resources Association
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• v.37 no.8
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• pp.613-622
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• 2004

The simulation results of final closing by the developed model considering the flows through tide embankment of non-Darcy and through sluice gate agree well to the observed data which shows the model applicability. In comparative analysis with observed data, the simulation results by Homma(1958) are more accurate than those by Na(1987). The free flow equation with discharge coefficient, regardless of free or submerged flows, by Na based on the submergence ratio is applicable to the engineering practices. Because two simulated discharges are greater than the actual one, the correction of discharge coefficients reflecting the irregular section of actual closing gap situation is necessary. In the hydraulic analysis of final closing, the flow through tide embankment has been generally analysed by Darcy. Hydraulic analysis by the correct discharge through tide embankment of non-Darcy flow is necessary, because the ratio between flows through tide embankment and closing gap is relatively great at final closing.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.63-72
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• 2005

Rocks are dumped to soft marine ground in order to improve trafficability and construction conditions in the tideland reclamation construction sites. Though this rock layer under earth fill has caused in a serious seepage problems after construction, seepage behaviors of this embankment structure is not correctly investigated. Water flow through rock layers is, in general, known as Non-Darcy's flow. However, the embedded rock layer under earth fill is not known whether its flow is governed by Darcy's or Non-Darcy's law. Therefore, a numerical analysis, laboratory model test and filed investigations were performed for analyzing the those seepage characteristics in this research. Results show that there is significance of $95\%$ of confidence between observed heads and seepage rates, and the calculated ones by SAMTLE which is developed under the assumption that the water flows through the two-layer system obey the Darcy's flow. And after operating the hydraulic gradient(i) of $0.10\~0.55$ upon laboratory model, these seepage characteristics of the embedded rock layer show that Reynolds Numbers are less than 10 and the relationship between these velocities of rock layer(v) and hydraulic gradients(i) is linearly proportional with more than 0.79 of the coefficient of correlation $(R^2)$. And the Reynolds Number of the velocity calculated by the relation of v=ki in the embedded rock layer of OO sea dike is $1\~6$. It shows also laminar flow. Based on these results, it is concluded that the seepage characteristics of embedded rock layer under earth fill can be laminar and Darcy's flow.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.213-223
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• 2004

The discharges of groundwater flow were estimated using Darcy's method along the coastal zone in the Masan Bay. The estimates using the information, i.e., groundwater level, location of the observation well, hydraulic conductivity, the thickness of the aquifer, and coastline length, were 1.65% of the precipitation of the watershed. The estimated groundwater discharges through fractured rock aquifer and the aquifer with sedimentary material were $0.7\times10^4$$m^2/year$and $1.0\times10^7$$m^3/year$ respectively. Whereas, the discharge estimated by KORDI (2003) using isotopes method is about 20 times larger than the estimates from this study because of the influence of the re-circulated seawater through the coastal zone aquifer. In order to quantify this effect in detail, the groundwater levels and salinity changes in the observation wells located in the coastal zone should be continuously monitored and analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.201-209
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• 1993

The purpose of this study is to analyze the reliability of storm sewer system and AFOSM method is applied on Sinjeong detention basin area to decide the applicability of AFOSM method. The Rackwitz Algorithm, which is suitable for minimizing the error due to non-linearity, is used to find the failiure point. The performance functions are established to calculate the risk, rational formula is used to determine the load and Manning equation and Darcy-Weisbach equation are used to determine the sewer capacity, and the results are 0.119, 0.127, respectively. The Risk-Safety Factor relation for each return period is derived and the designing of storm sewer system based on reliability analysis is enabled.

• Magazine of the Korean Society of Agricultural Engineers
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• v.9 no.2
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• pp.1301-1305
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• 1967

Ground water flow can be studied with model test. Model test of ground water works are necessary for economic and safe design of the works. Also influence of the ground water flow to the durability and safety of hydraulic structures can be studied with this model. a. Sand model ; Water flow through porous media is the principle of sand model. Darcy's formula is the basic equation, $q=k{\frac{dh}{ds}}^{\circ}. The effect of the ground water flow on the grain system itself is represented with this model only. b. Hele-Shaw model ; In this model use is made of the viscous flow analogy. Viscous fluid such as glycerine flowing through two parallel plates depends on Poiseuille law, $q=-c{\frac{dh}{ds}}$. The analogue can be used vertically and horizontally. c. Heat model ; This is based on the analogy of the Fourier's law for heat conduction and Darcy's law for ground water flow. Especially unsteady problem can be studied with this model. A difficulty of the construction of this model is the isolation, which has to prevent losses of the heat. d. Electirc model ; Ohm's law for electric current is analogous to Darcy's law. Resistance material such as metal foil, graphite block, water with salt added, gelatine with salt added, ete. is connected to electric sources and resistor, and equi-voltage line is detected with galvanometer, $N_aCl$, $CuSo_4$, etc. are used as salt in the model. e. Membrane model ; This model is based on the facts that the deflection of a thin membrane obeys Laplace's equation if there is no load in the direction perpendicular to the membrane, and if the dellection is small.

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.23-29
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• 2024

In this paper, we propose a fast GPU-based method for representing pore flow, absorption, emission, and diffusion effects represented by cloth-liquid interactions using smoothed particle hydrodynamics (SPH), a particle-based fluid solver: 1) a unified framework for GPU-based representation of various physical effects represented by cloth-liquid interactions; 2) a method for efficiently calculating the saturation of a node based on SPH and transferring it to the surrounding porous particles; 3) a method for improving the stability based on Darcy's law to reliably calculate the direction of fluid absorption and release; 4) a method for controlling the amount of fluid absorbed by the porous particles according to the direction of flow; and finally, 5) a method for releasing the SPH particles without exceeding their maximum mass. The main advantage of the proposed method is that all computations are computed and run on the GPU, allowing us to quickly model porous materials, porous flows, absorption, reflection, diffusion, etc. represented by the interaction of cloth and fluid.

• Journal of Korea Water Resources Association
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• v.44 no.1
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• pp.9-22
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• 2011

A 1D numerical model for steady flow, based on the energy equation, was developed for natural rivers with emergent vegetations on floodplains and banks. The friction slope was determined by the friction law of Darcy-Weisbach. The composite friction factor of the each cross section was calculated by considering bottom roughness of the main channel and the floodplains, the flow resistance of vegetations, the apparent shear stress and the flow resistance caused by the momentum transfer between vegetated areas and non-vegetated areas. The interface friction factor caused by flow interaction was calculated by empirical formulas of Mertens and Nuding. In order to verify the accuracy of the suggested model, water surface elevations were calculated by using imaginary compound channels and the results of calculations were compared with that of the HEC-RAS. The sensitivity analysis was performed to confirm changed friction factors by vegetations density etc. The suggested model was applied to the reach of the Enz River in Germany, and estimated water surface elevations of the Enz River were compared with measured water surface elevations. This model could acceptably compute not only water surface elevations with low discharge but also that with high discharge. So, the suggested model in this study verified the applicability in natural rivers with emergent vegetations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2B
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• pp.139-147
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• 2012

This study is derived relationships of the resistance coefficients of Darcy-Weisbach and Manning for flow resistance and the dimensionless velocity using many field measurements for 1,875 rivers consist of sand 179, gravel 992, cobble 651 and boulder 53 channels in natural rivers, respectively. The relationships of power law forms are developed as a function of flow discharge, friction slope, and relative submergence by the regression and the semi-empirical method. The measurements distribution of Manning resistance coefficients by the Box-Whisker Plots show the values which ranges from 0.004~0.151 for sand, 0.008~0.250 for gravel, 0.015~0.327 for cobble, 0.023~0.444 for boulder in natural rivers, respectively. Relationships of these semi-empirical and resistance coefficients will be useful to give information in hydraulic engineering.