• Journal of Soil and Groundwater Environment
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• v.11 no.6
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• pp.28-34
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• 2006

Laboratory column tests using $Cl^-$ tracer were conducted to study the correlation of soil particle distribution and hydrodynamic dispersion mechanism with three kinds of ununiformed soil samples, in which the ratio of gravel and sand versus silt and clay is 24.5 for S-1 soil, 4.48 for S-2 soil, and 0.4 for S-3 soil. Chloride breakthrough curves with time were fitted with gaussian functions. The relative concentrations of chloride were converged to 1.0 after 0.7 hours for S-1, 6.3 hours for S-2, and 389 hours for S-3. Average linear velocity, longitudinal dispersion coefficient, and longitudinal dispersivity were calculated by chloride breakthrough curves. Longitudinal dispersion coefficients were $1.20{\times}10^{-4}\;m^2/sec$ for S-1, $8.87{\times}10^{-7}\;m^2/sec$ for S-2, and $1.94{\times}10^{-9}\;m^2/sec$ for S-3. Peclet numbers calculated by the molecular diffusion coefficient of chloride and the mean grain diameters of soils were $2.59{\times}10^2$ for S-1, $6.27{\times}10^0$ for S-2, and $1.35{\times}10^{-4}$ for S-3. Mechanical dispersion was dominant for the hydrodynamic dispersion mechanism of S-1. Both mechanical dispersion and molecular diffusion were dominant for the hydrodynamic dispersion mechanism of S-2, but mechanical dispersion was ascendant over molecular diffusion. Hydrodynamic dispersion in S-3 was occurred mainly by molecular diffusion. When plotting three soils on the graph of $D_L/D_m$ versus Peclet number produced by Bijeljic and Blunt (2006), the values of $D_L/D_m$ for S-1 and S-2 were more than 2.0 order compared to their graph. S-3 was not plotted on their graph because the Peclet number was as small as $1.35{\times}10^{-4}$.

• Korean Journal of Medicinal Crop Science
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• v.12 no.1
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• pp.10-16
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• 2004

This study was carried out to investigate the difference of growth characteristics and the content of root chemical components in four years old ginseng by paddy and upland cultivation at farmers' field in Korea. Proportions of silt, clay, liquid phase and porosity were higher in paddy soil than upland soil. The range of liquid phase was $17.5{\sim}19.5%$ in paddy and $7.0{\sim}12.8%$ in upland during growth period. EC and the other contents of OM, $NO_3^-,\;K_2O$, and Mg in paddy soil were higher than those of upland soil, while the contents of $P_2O_5$ and Ca were less than those of upland soil. The levels of chemical components of tested soil exceeded recommended range in EC, $NO_3^-$ and Ca of paddy soil, and in $P_2O_5$ and Ca of upland soil. Stem length, fresh root weight and total dry weight per plant in paddy were greater than those of upland. Root weight in paddy-ginseng showed a great increase on September, while it was not increased in upland because of early defoliation. Net assimilation rate and crop growth rate by paddy and upland cultivation showed distinct differences on May and September, and those of paddy-ginseng were higher than those of upland-ginseng. Yield and ratio of red-colored root showed no significant difference by paddy and upland cultivation, while significant differences were observed in diameter and length of primary root, contents of crude saponin and 50% ethanol extracts of primary root, and water content of root. Hardness of primary root showed no significant difference by paddy and upland cultivation until August, but it showed distinct difference on September, at which the hardness in upland cultivation was drastically decreased.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.274-280
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• 2005

Enormous amount of oyster-shell waste has been illegally disposed at oyster farm sites along the southern coast of Korea and then made a serious problem in environmental side. To increase the consumption of oyster shell meal as a soil amendment, the effects of oyster shell meal on soil properties and spring Chinese cabbage productivity were evaluated in silt loam soil to which 0, 4, 8, 12 and $16Mg\;ha^{-1}$ of oyster-shell meal fertilizer were added. Hydrated lime treatment ($2Mg\;ha^{-1}$) was selected as a control. Oyster-shell meal fertilizer, which made by a simple crushing and has high alkalinity as a calcium materials, had significant effects on neutralizing acid soil and on supplying calcium element. Spring Chinese cabbage yields increased with shell meal application. Plant uptakes of macro-nutrients such as P and C, and micro-nutrient such as B were significantly increased by oyster-shell meal application and then contributed to promote Chinese cabbage growth. The highest yield was achieved following the addition of $8Mg\;ha^{-1}$ shell meal application, and the same yield with that in lime treatment was at the $4Mg\;ha^{-1}$. Oyster-shell meal had more substantial effect on suppling calcium and on improving soil pH than that of lime. In conclusion, oyster shell meal fertilizer could be a good supplement to other inorganic soil amendments to improve nutrient balances in upland soils.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.1-14
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• 2010

Changes in wetland soil properties of two constructed wetlands after their constructions were compared to those of a natural wetland to determine if they could be used for the evaluation of the success of constructed wetlands and the assessment of their functions. One natural wetland as a reference wetland and two constructed wetlands(treatment wetland and experimental wetland) with different contaminant inflow characteristics were selected for this study. Major physicochemical properties of wetland soil such as soil texture, water content, pH, CEC(cation exchange capacity), organic matter content, total nitrogen, and available phosphorus were monitored to investigate the effects of inundation and accumulation of organic matters and nutrients on the wetland soil development. There was a clear difference in soil texture between the natural wetland and the constructed ones, with the high sand content in the constructed wetlands as compared to the high clay content in the natural one. Gradual increases of silt and clay contents over time were observed in the constructed wetlands. The soil of the natural wetland was higher in water content and organic matter but lower in pH than those of the constructed wetlands. The pH of the constructed wetlands reached near neutral ranges after initial increase. CEC and nutrient concentrations of the constructed wetlands seemed to be affected mainly by outside inflows of organic matter and contaminants. Concentrations of organic matter and nutrients decreased over time in the experimental wetland where surface and deep soils with different characteristics were mixed during its construction, suggesting that changes in soil properties during wetland constructions may affect the development of wetland soils or wetland biogeochemistry. This study showed that changes in physicochemical properties of soils in constructed wetlands could be used to assess the success of constructed wetlands and their functions, and also the importance of reference wetlands for the appropriate assessment.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.330-335
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• 2009

This study was conducted to reclassify Jangho series based on the second edition of Soil Taxonomy : A Basic System of Soil Classification for Making and Interpreting Soil Surveys. Morphological properties of typifying pedon of Jangho series were investigated and physico-chemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Jangho series has very dark grayish brown (10YR 3/2) gravelly silt loam A horizon (0~14 cm), very dark brown (7.5YR 3/2) silty clay BAt horizon (14~31 cm), dark brown (7.5YR 3/4) silty clay Bt1 horizon (31~58 cm), brown (7.5YR 4/4) silty clay Bt2 horizon (58~90 cm), and brown (7.5YR 4/4) clay Bt3 (90~120 cm) horizon. That is developed on river terraces. The typifying pedon has an argillic horizon from a depth of 14 to more than 120 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. That can be classified as Ultisol. The typifying pedon has 0.9 % or more organic carbon in the upper 15 cm of the argillic horizon, and can be classified as Humult, which is reported for the first time in Korea. That does not have fragipan, kandic horizon, sombric horizon, plinthite, etc. in the given depths, and keys out as Haplohumult. Also that meets the requirements of Typic Haplohumult. That has 35 % or more clay at the particle-size control section, and has mesic soil temperature regime. Jangho series can be classified as fine, mixed, mesic family of Typic Haplohumults, not as fine silty over clayey, mixed, mesic family of Mollic Hapludalfs.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.433-445
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• 2021

Plasma blasting by high voltage arc discharge were performed in laboratory-scale soil samples to investigate the fluid penetration efficiency. A plasma blasting device with a large-capacity capacitor and columnar soil samples with a diameter of 80 cm and a height of 60 cm were prepared. Columnar soil samples consist of seven A-samples mixed with sand and silt by ratio of 7:3 and three B-samples by ratio of 9:1. When fluid was injected into A-sample by pressure without plasma blasting, fluid penetrated into soil only near around the borehole, and penetration area ratio was less than 5%. Fluid was injected by plasma blasting with three different discharge energies of 1 kJ, 4 kJ and 9 kJ. When plasma blasting was performed once in the A-samples, penetration area ratios of the fluid were 16-25%. Penetration area ratios were 30-48% when blastings were executed five times consecutively. The largest penetration area by plasma blasting was 9.6 times larger than that by fluid injection by pressure. This indicates that the higher discharge energy of plasma blasting and the more numbers of blasting are, the larger are fluid penetration areas. When five consecutive plasma blasting were carried out in B-sample, fluid penetration area ratios were 33-59%. Penetration areas into B-samples were 1.1-1.4 times larger than those in A-samples when test conditions were the same, indicating that the higher permeability of soil is, the larger is fluid penetration area. The fluid penetration radius was calculated to figure out fluid penetration volume. When the fluid was injected by pressure, the penetration radius was 9 cm. Whereas, the penetration radius was 27-30 cm when blasting were performed 5 times with energy of 9 kJ. The radius increased up to 333% by plasma blasting. All these results indicate that cleaning agent penetrates further and remediation efficiency of contaminated soil will be improved if plasma blasting technology is applied to in situ cleaning of contaminated soil with low permeability.

• Journal of the Korean Geotechnical Society
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• v.29 no.10
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• pp.67-74
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• 2013

The objective of this study was to identify the effect of engineering properties on the resilient modulus ($M_r$) of cohesive soils as subgrade. Eight representative cohesive soils representing A-6, and A-7-6 soil types collected from road construction sites, were tested in the laboratory to determine their basic engineering properties. The laboratory tests for the engineering properties were Atterberg limits test, sieve analysis, hydrometer test, Standard Proctor compaction test, and unconfined compressive strength test. Resilient modulus test and unconfined compressive strength test were conducted on unsaturated cohesive soils at three different moisture contents (dry of optimum moisture content, optimum moisture content, and wet of optimum moisture content). The increase in moisture content considerably affected the decrease in the resilient modulus. The resilient modulus increased with an increase in maximum unconfined compressive strength, percent of clay, percent of silt and clay, liquid limit and plasticity index. The resilient modulus decreased with an increase in percent of sand.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.2
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• pp.93-98
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• 1976

The present paper is a part of a study aimed at gaining information on the origin, mode of deposition, and characteristics of volcanic soils in Jeju. Volcanic activity of Jeju island has extremely influenced on the formation of various soils. Polysequum phenomenon of soils is one of outstanding soil genesis in Jeju. The typical polysequum soils was collected and analyzed by morphological, physico-chemical, mineralogical and micromorphological approaches The results are as follows: 1. The soils consists of polysequa, A and B horizons from volcanic ashes, unconsolidated volcanic sand layer and B(I) horizons from residual basalts. 2. The lithological discontinuity is also very distinct; silt loam from volcanic ashes, sand (II) from volcanic sand and clayey (III) from basalts. 3. Volcanic sand layer seems to be influenced by lava flow. The properties of it are similar to volcanic ashes rather than beneath residuum in micromorphological aspects. In micromorphological, this layer is gradually changed into soils. 4. Dominant clay minerals are allophane in A and B horizons from volcanic ashes and kaoline, vermiculite and illite from residual basalts. 5. The soils are not developed. There is no formation of argillic horizon in subsurface layers.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.167-168
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• 2003

The Upo wetland, the largest natural wetland in Korea, is located in Changnyeong-gun, Gyeongsannam Province ($35^{\circ}33'$ N, $128^{\circ}25'$ E), and 70 km upstream from the Nakdong River estuary. Unlike most other Korean wetlands that have been destroyed under the name of economic development, the Upo wetland has been able to preserve its precious ecosystem throughout the years. Thanks to increased public awareness about natural wetlands and environmental conservation, the Korean Ministry of Environment designated the Upo wetland an 'Ecological Conservation Area' on July 26th, 1997. On March 2nd of the following year, the Upo wetland (8.54 $\textrm{km}^2$) was designated a 'Protected Wetland' in accordance with the international Ramsar Treaty. A 4.49m long (from 9.73 to 5.24 m in altitude) UP-1 core ($35^{\circ}33'05"N$, $128^{\circ}25'17"E$), recovered in the marginal part of the Upo wetland, is divided into eight buried paleosol units of different ages on the basis of the abundance of color mottles and vertical color variations (Aslan et al., 1998). Radiocarbon datings suggested that the paleosol profile represent the last 5700 years. The entire section of the core was more or less subjected to pedogenetic processes, and shows very weak to moderate soil profile development. These Holocene paleosols are therefore regarded as synsedimentary soils of deluvium (deposits formed by floods) origin (Sycheva et al., 2003). Unit 1 to 5 paleosols are generally silt-rich and exhibit moderate profile development. The boundaries between the units are somewhat distinguishable, but not so clear cut. This is due to variable repeated combination of accumulation, denudation and soil forming processes within various periods. Mottle textures gradually decrease in abundance with increasing clay content in Unit 6, which results in weak profile development. The lower boundary of Unit 6 lies around about 2000 yrBP, the beginning of Subatlantic in Korea (Kim et al., 2001). Abrupt sediment textural change is detected in Unit 7, which is interpreted to indicate the human activities on the Upo wetland. Unit 8 represents the recent soil forming processes. The preliminary results of this ongoing study imply the primary factor for pedogenetic processes is the water table fluctuations related to the sedimentary textures like grain size distributions, and the geomorphological stability of the Upo wetland.o wetland.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.535-543
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• 2016

This study has been carried out to evaluate the CBR characteristics and the correlations among every soil properties of National road in Yeongnam region. Total of 480 soil samples were collected from 41 administrative districts for more than 30 years. Their physical and mechanical properties such as natural water content, the Atterberg limit, No. 200 sieve passing, the compaction test and the CBR test results were involved. The soils in Yeongnam region, SM, SC, SP and CL by USCS have predominated approximately 79%. The test results show that average CBR values of gravel and sand range from 12.7% to 20.3% and those of silt and clay range from 4.8% to 7.1%. It means that average CBR values of fine grained soils are less than a half of coarse grained one. Natural water content, No. 200 sieve passing, optimum moisture content and maximum dry density of soils are well correlated with CBR values. Especially, it presents that No. 200 sieve passing is the best correlation factor with CBR value. If consider the partition off this region into 6 zones of classified by mother rock, the correlation between CBR value and every soil properties tends to increase. It is suggested that tables, figures and the regressions described in this paper may be available for designers and engineers to understand the characteristics of an embankment materials in Yeongnam region.