• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.4
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• pp.85-93
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• 1988

This laboratory study was carried out in order to produce fundamental data for analyzing salt movement and desalinization effects, using samples of silt loam soil collected in Gyehwado and Daeho reclaimed tidelans, and samples of silty clay loam soil collected in Kimie tideland. Desalinization experiments with gypsum treatment were performed to analyze changes of the hydraulicc conductivity with changes of the soil property and the salt concentration during the desalinization of reclaimed tideland soils by leaching through the subsufface drainage, and correlations between factors infl uencing the reclamation of salt affected soils were analyzed by the statistical method. The results were summarized as follows: 1. The reclaimed tideland soils used in this study were saline-sodic soils with the high exchangeable sodium percentage and the high electrical conductivity. 2. Changes of the hydraulic conductivity with the amount of leaching water and the leaching time elapsed were affected by the amount of gypsum except exchangeable sodium and clay contents. The regression equation between the depth of water leached per unit depth of soil (Dw / Ds : X) or the square root of the leaching time elapsed (T $^1$ $^2$ : X) and the relative hydraulic conductivity (HCr:Y) could be expressed in Y=a . bx. 3. The more exchangeable sodium and clay contents regardless of the amount of gypsum, the more the leaching time was required until a given volume of water was leached through the soil profile. The regression analysis showed that the relationship between the depth of water leached per unit depth of soil(Dw /Ds:X) and the square root of the leaching time elapsed(T$^1$$^2$ :Y) could be described by Y=a . Xb. 4. The hydraulic conductivity was influenced to a major degree by the salt concentration provided that the electrical conductivity was below 10 mmhos / cm during the desalinization of reclaimed tideland soils. The regression equation between the relative electrical conductivity ( ECr : X) and the relative hydraulic conductivity (HCr:Y) could be expressed in Y=a + b . X-$^1$. 5. In conclusion, the hydraulic conductivity, leaching requirements and the leaching time elapsed can be estimated when the salt concentration decreases to a certain level during the desalinization of reclaimed tidelands, and the results may be applied to the analysis of salt movement and desalinization effects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2369-2379
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• 2013

The Soil-Water Characteristics Curve (SWCC) is affected by the initial density of soil under unsaturated condition. Also, the characteristic of hydraulic conductivity is changed by the initial density of soil. To study the effect of initial density of unsaturated soil, SWCC and the Hydraulic Conductivity Function (HCF) of Jumoonjin sand with various relative densities, 40%, 60% and 75% were measured in both drying and wetting processes. As the results of SWCC estimated by van Genuchten (1980) model, the parameter related to Air Entry Value(AEV), ${\alpha}$ in the wetting process is larger than that in drying process, but the parameters related to the SWCC slope, n and the residual water content, m are larger than those in wetting process. The AEV is increased or Water Entry Value (WEV) is decreased with increasing the relative density of sand. The AEV is larger than the WEV at the same relative density of sand. As the results of HCF estimated by van Genuchten (1980) model which is one of the parameter estimation methods, the unsaturated hydraulic conductivity maintained at a saturated one in the low level of matric suctions and then suddenly decreased just before the AEV or the WEV. The saturated hydraulic conductivity in drying process is larger than that in wetting process. The saturated hydraulic conductivity is decreased with increasing the relative density of sand in both drying and wetting processes. Also, the hysteresis in unsaturated HCFs between drying and wetting process was occurred like the hysteresis in SWCCs. According to the test results, the AEV on SWCC is decreased and the saturated hydraulic conductivity is increased with increasing the initial density. It means that SWCC and HCF are affected by the initial density in the unsaturated soil.

• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.120-129
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• 1996

This study was carried out to investigate the hydraulic architecture such as relative hydraulic conductivity, Leaf specific conductivity(LSC), Huber value, Specific conductivity of the stem, branch and Junctions of stem-to-branch in Quercus mongolica trees. The hydraulic architecture of various hydraulic conductivities of stem and branch was described. The results obtained were summarized as follows : 1. The range of relative hydraulic conductivity was $2.5526{\times}10^{-12}$ to $1.2260{\times}10^{-10}m^2$ in stems, $1.6279{\times}10^{-11}$ to $6.8378{\times}10^{-11}m^2$ in branches. The relative hydraulic conductivities increased with decreasing diameter of stem and branch. The relative hydraulic conductivity of one-year-old terminal shoots were two times greater than that of the lateral shoots. 2. LSC value was larger at the top than at the base in stem. LSC is much smaller in branches than in stem ; especially smallest at branching part. 3. Hydraulic conductivities of the branching part appeared the different values with the 4 type and 4 type. Relative hydraulic conductivity, LSC, Specific conductivity and mean vessel diameter in type branching part were larger in stem than in branch part, but not found in the branching part of Y type. 4. LSC and Specific conductivity of stem increased with decreasing diameter, but Huber value slowly increased with decreasing diameter ; especially highest at less than 1cm diameter. 5. LSC, Huber value, and mean diameter of vessels were larger at 1-year-old leader shoots than at lateral shoots. 6. The mean vessel diameter in various parts of a tree decreased with decreasing diameter of stem, but the number of vessels per unit area($mm^{-2}$) increased reversely. Mean vessel diameter in stem decreased sharply at earlywood and slowly at latewood with decreasing diameter of stem.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.341-345
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• 2004

An attempt has been made in this study to evaluate an applicability of Relative Effective Porosity Model (REPM) as a method for estimating saturated hydraulic conductivity (K$_{s}$) for homogeneous coarse, medium, and fine sands. The saturated hydraulic conductivities obtained from REPM are converted into average linear velocities using Darcy's Law and compared with the results from experimental tracer tests for homogeneous coarse, medium, and fine sand layer. Two types of tracer tests analyses, analytical solution using CXTFIT and moment methods, are performed to obtain reasonable linear velocity range for each layer. For the coarse and medium sands, the converted average linear velocity from REPM is in the velocity range obtained from tracer tests. However, small difference between the results from REPM and tracer tests is found for the fine sands. These results show that REPM gives reasonable estimates of saturated hydraulic conductivity.y.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.1
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• pp.11-23
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• 2015

In this study the laboratory test for hydraulic conductivity and the seepage analysis with finite element method on measurement section of sea dike embankment were performed for the purpose of estimating the relative density of embankment from the measured pore water pressures, and both results of the test and the analysis were coupled with the method of estimating seepage blocking state with the hydraulic head loss rate in sea dike embankment. The relationship of void ratio vs hydraulic head loss rate was obtained by setting hydraulic conductivity as common ordinate on the relationships between the void ratio and the hydraulic conductivity and between the hydraulic conductivity and the hydraulic head loss rate. The void ratio on the segment between measuring points was calculated from the coupled relationship of the void ratio vs the hydraulic conductivity. The allowable upper and lower limits of hydraulic head loss rate and those of void ratio on the safety were generated from the coupled relationship between the laboratory compaction test and the sedimentation test. Current hydraulic head loss rate and void ratio were evaluated in the allowable range between upper and lower limits.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.1
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• pp.69-77
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• 2014

Unsaturated hydraulic conductivity of the bentonite-buffer was evaluated using the relative humidity data. The method for calculating unsaturated hydraulic conductivity was deduced from the general analytical equation representing the movement of water in unsaturated media, which was applied to the experimental results of water infiltration tests for identifying the behavior of unsaturated hydraulic conductivity according to the water saturation. Unlike the saturated condition, the hydraulic gradient and water flux were irregularly changed, and the unsaturated hydraulic conductivity was increased with increasing the experimental time. Swelling of bentonite grains due to the water absorption increased the volume and size of pore within bentonite, resulting in the increase of water velocity and unsaturated hydraulic conductivity. This result suggested the necessity of further investigation on the correlation between the swelling degree of bentonite-buffer and unsaturated hydraulic conductivity. The method used in this study can be useful technique for evaluating long-term hydraulic performance of bentonite-buffer in the radioactive waste disposal system.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.108-119
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• 1996

Several parameters of hydraulic architecture relating to hydraulic conductance in xylem vessels were investigated in the current-year shoots of six species of deciduous oak trees. The above parameters were also investigated in the sprouts of Quercus mongolica and Q. variabilis, as well as in the seedlings of Q. mongolica and Q. acutissima. The values of specific conductivity, leaf specific conductivity and Hagen-Poiseuille's relative hydraulic conductivity relating to vessel diameter of Q. dentata were the highest in all of the species studied. The above values of most of the species studied were higher in May-June than in September-October because of increasing the vessel embolism by cavitation and so on through the growing season. The estimated values of relative hydraulic conductivity of vessel by Hagen-Poiseuille's empirical equation and the real values of hydraulic conductivity presented positive relationships in most of the species studied. Huber value and leaf specific conductity using leaf area or leaf weight generally exhibited similar patterns each other even if having some exceptions. The hydraulic conductances of sprouting shoots were much better than those of normal growing shoots in Q. rnongolica and Q. variabilis. The specific conductivity and leaf specific conductivity were rapidly decreased by the vessel embolism through cavitating just after cutting the shoots in Q. mongolica and Q. acutissima seedlings. Diurnal changes of the conductivities in the seedlings of Q. mongolica and Q. acutissima presented the possibility of their self-controlling of conductance by active moisture absorption under mild water stress. Specific conductivity and leaf specific conductivity, and so on of Q. acutissima seedlings subjected to periodical moisture stress or not have decreased through the growing season, but the influences of moisture stress to the conductance were not proved definitely because of influencing similarly and simultaneously to the development of xylem and leaf having inverse relation in the influences. The values of conductivities were higher generally in middle or upper parts of stems than root collar in the seedlings.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.220-229
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• 1998

This study was performed to compare the characteristics of hydraulic conductivity such as relative conductivity(RC), leaf specific conductivity(LSC), Huber value(HV), specific conductivity(SC), and diameter of vessels(${\mu}m$) and number of vessels($No./mm^2$) in branch junctions of the twenty-one deciduous broad-leaved species. The hydraulic conductivities of branch junctions decreased with increasing junction angle between stem and branch, and with decreasing diameter of branch. The RC and LSC of branch junctions related to branching types(ㅏ, Y, ${\Psi}$ type) were much lower in ㅏ and ${\Psi}$ types than in Y type. The diameter and number of vessels remarkably reduced in branch junctions as compared with the stem and branch.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.722-726
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• 2011

The management standard on soil conditions in 'Fuji' apple to produce high quality fruit were not yet made. Therefore, this study was carried out to investigate the optimum soil environmental conditions of ten contents on production of high quality fruit in 'Fuji' apple. The soil and fruit characteristics were analyzed at total 60 orchards in major apple producing areas such as Chungju, Moonkyeung, yeongju, andong, yeosan and yeongcheon (10 orchards an area). The soil environmental factors affected fruit weight was highest relative contribution in saturated hydraulic conductivity of 36.5%. The bulk density and soil pH were low as relative contribution. The fruit weight was influenced by soil physical properties more than soil chemical properties. The soil environmental factors affected sugar content were hydraulic conductivity of 28.3% and organic matter content of 18.2%. The cultivation layer depth and soil pH were low as relative contribution. The fruit coloring was highest relative contribution in saturated hydraulic conductivity 55.9%. while soil pH, cation and soil texture were low. Fruit coloring was high influenced over 70% by soil physical properties. Finally, relative contribution on fruit quality related with sugar content, fruit weight, and coloring were high influenced by saturated hydraulic conductivity of 21.% and organic matter content of 18.7% but bulk density and cultivation layer depth were low relative contribution. The fruit growth and saturated hydraulic conductivity in 'Fuji' apple were very closely related. Therefore, orchard soil management to produce high quality fruit was very importance drainage management and organic matter application. We concluded that scientific soil management is possible by qualifiable of soil management factors.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.220-223
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• 2006

To investigate the effect of solution pH and particle size of Na-bentonite on swelling characteristics and relative hydraulic conductivity, four kinds of acids and two alkali were selected. The results showed that the swelling was decreased to half of the original Na-bentonite's swelling index. Also the decrease in SI was most distinctive in pH 3.5 of HCl. But changes of swelling index between initial and stabilized were minimal in alkali treatment, compared to the change by acid treatment. No flux was detected under atmospheric pressure although there was drastic decrease in swelling. However, leaching started after application of 1.5 bars of air-pressure equivalent to 15 m of water head.