• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.13
• /
• pp.77-81
• /
• 1973

The experiment was carried out to make clear the root characters and relationships among some quantitative characters of soybeans. The results obtained are summarized as follows: 1. Stem diameter was shown the greater growing in thickness after one month from sowing than the earlier stage, and the greater growing was shown in fertile bed soil than in sand soil. 2. The elongation of plant top in soybean plant was also shown the greater rate in bed soil than in sand soil 3. The length of plant root was longer than the length of plant top in the earlier stage of growing, and the length of root was much greater in sand soil than in fertile bed soil. 4. Weight of plant top was shown more in bed soil than in sand soil, but this tendency was shown more greater rate in the length of plant top than in weight of plant top. 5. Weight of root was more compared with weight of plant top in the earlier stage of growth, and also more greater rate was shown in sand soil than in fertile bed soil. 6. Highly significant correlations were shown among five quantitative characters, namely stem diameter, length of top, weight of top, length of root and weight of root, etc.

• Korean Journal of Organic Agriculture
• /
• v.21 no.1
• /
• pp.69-78
• /
• 2013

This study was carried out to evaluate nitrogen availability of applied fertilizer and to investigate yield and growth of Korean kimchi cabbage as affected by amount of fertilizer and soil fertility in organic farming applied various fertilizers in rainshelter. The head weight of Korean kimchi cabbage cultured in infertile soil (sand loam) with no amendments was very low. and that in fertile soil (clay loam) was higher than in infertile soil (sand loam). The head weight of Korean kimchi cabbage as affected by amount of fertilizer was more variable in infertile soil (sand loam) than in fertile soil (clay loam). Nitrogen availability of applied fertilizer by Korean kimchi cabbage was lower in fertile soil (clay loam) than in infertile soil (sand loam) and the lower that was, the more fertilizer applied. By application of poultry manure compost 20Mg ha-1 and natural mineral materials such as guano, phosphate rock, and potassium magnesium rock equal to amount of fertilizer recommended in conventional farming, the yield of Korean kimchi cabbage in infertile soil (sand loam) with 1% organic matter came up to 90% of the yield in fertile soil (clay loam) with 6% organic matter. Therefore natural mineral materials such as guano for N source, phosphate rock for P source, and potassium magnesium rock for K source may be able to use as environmental-friendly fertilizers in organic Korean kimchi cabbage production in highland.

• Tunnel and Underground Space
• /
• v.28 no.6
• /
• pp.584-595
• /
• 2018

This study conducted direct shear test on about 290 sorts of materials such as sandy soil, clayey soil and gravely soil to present proper standard on shear strength of soil. Shear strength of soil in large scale tends to show that angle of internal friction increases as sand contents grow and it ranges $23.5^{\circ}{\sim}34.9^{\circ}C$ with cohesion of 2.0 kPa~15.7 kPa. Elastic modulus was visibly distinct by load, and which increased approximately 80% as vertical load grows. Angle of internal friction arranging $15.0^{\circ}{\sim}28.6^{\circ}$ on clayey soil decreased as clay contents rises and cohesion increase in regular scale. Elastic modulus tends to increase initial elastic modulus with almost same growing rate. While angle of internal friction on gravely soil indicates $29.9^{\circ}{\sim}36.7^{\circ}$ which hardly shows distinctive features. According to test in detail, cohesion of SW (well-graded sand), SP (poorly-graded sand), SC (clayey sand) and SM (silty sand) indicates value by 94%, 78% and 59% comparing to SC, SW and SP respectively. Angle of internal friction of ML (low-liquid limit silt) and CL (low-liquid limit clay) appears almost same features, and MH (high-liquid limit silt) despite of 88% value of ML. Cohesion among them varies with similar growing rate.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.11 no.6
• /
• pp.81-90
• /
• 2008

Recently, geofiber(polyester) reinforced soil was added on soil-seed mixture spray to control erosion and to improve vegetation growth on rocky slope sites. This research was conducted to compare vegetation effects and soil hardness on three types of soil-seed mixture spray on stone gabion river bank [A type : soil-seed mixture spray underlying 30cm thick sand with geofiber(geofiber reinforced soil system), B type : soil-seed mixture spray underlying 30cm thick sand without geofiber, C type : soil-seed mixture spray]. Evaluation were made concerning vegetation coverage, soil hardness and moisture content. The results of this study showed that A type system was effective for the growth of vegetation and soil hardness when compareed to B type and C type. A type and B type showed higher covering rate than C type on stone gabion river bank, and especially A type showed the highest covering rate. Soil hardness and water content were high on A type vegetation system compared to B type and C type. We noted that high soil hardness and high moisture content with geofiber(geofiber reinforced soil system) were effective both to control erosion from water current impact and to be high coverage and species of vegetation on stone gabion river bank.

• Journal of the Korean GEO-environmental Society
• /
• v.6 no.1
• /
• pp.23-31
• /
• 2005

The "Silt Pond" is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Reclamation works in the Silt Pond commenced in the mid of 1990s. A considerable amount of subsurface investigation inclusive of sampling, field vane and density logging tests were carried out prior to the reclamation of the Silt Pond. Since material in the Silt Pond is extremely soft, filling was done by spreading sand with high water content in thin and equal thickness lifts, allowing the stability of the slurry-like foundation. Despite the extreme care taken, failures occurred during the sand spreading phase. A large piece of high strength geotextile measuring $900m{\times}700m$ was placed to strengthen the slurry like soil foundation at locations where the ultra-soft soil was found to be exposed. Following the remedial works, the Silt Pond was again reclaimed by sand spreading up to +4.0m CD. The success of the reclamation was confirmed by marine CPT profiling.

• Computers and Concrete
• /
• v.17 no.6
• /
• pp.787-799
• /
• 2016

Climate anomalies in recent years, numerous natural disasters caused by landslides and a large amount of entrained sands and stones in Taiwan have created significant disasters and greater difficulties in subsequent reconstruction. How to respond to these problems efficaciously is an important issue. In this study, the sands and stones were doped with recycled materials (waste LCD glass sand, slag powder), and material was mixed for recycled ready-mixed soil. The study is based on security and economic principles, using flowability test to determine the water-binder ratio (W/B=2.4, 2.6, and 2.8), a fixed soil: sand ratio of 6:4 and a soil: sand: glass ratio of 6:2:2 as fine aggregate. Slag (at concentrations of 0%, 20%, and 40%) replaced the cement. The following tests were conducted: flowability, initial setting time, unit weight, drop-weight and compressive strength. The results show that the slump values are 220 -290 mm, the slump flow values are 460 -1030 mm, and the tube flow values are 240-590 mm, all conforming to the objectives of the design. The initial setting times are 945-1695 min. The unit weight deviations are 0.1-0.6%. The three groups of mixtures conform to the specification, being below 7.6 cm in the drop-weight test. In the compressive strength test, the water-binder ratios for 2.4 are optimal ($13.78-17.84kgf/cm^2$). The results show that Recycled ready-mixed soil materials (RRMSM) possesses excellent flowability. The other properties, applied to backfill engineering, can effectively save costs and are conducive to environmental protection.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.1
• /
• pp.1-7
• /
• 2023

Super absorbent polymers (SAPs) are hydrophilic molecules that can absorb large amounts of water. This study was conducted to investigate the enhancement of the physicochemical properties of sand soil blended with three SAPs imbibed with 100, 150, and 200-fold water. Three treatments were applied, namely, 100SAP, 150SAP, and 200SAP. The three SAPs were blended at concentrations of 0% (control), 3%, 5%, 7%, and 10% with sand. The pH, electrical conductivity, and cation exchangeable capacity (CEC) of soil blended with the three SAPs were pH 6.35-6.46, 0.09-0.65 dS/m, and 1.42-1.92 cmol_c/kg, respectively, and their capillary porosity, total porosity, and saturated hydraulic conductivity were 21.0-29.3%, 39.2-48.7%, and 272-470 mm/hr. CEC, capillary porosity, total porosity, and saturated hydraulic conductivity of soil were positively correlated with the ratio of the SAPs (p<0.01). These results indicate that blending sand soil with SAPs increased CEC, capillary porosity, and saturated hydraulic conductivity, thus improving the nutrient-retention capacity, water-retention capacity, and permeability of the soil.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.623-630
• /
• 2000

In this study, it was to investigate the possibility to use the converts slag, by product in producing steel as a substitute material with sand that is used fur a civil construction materials, in developing techniques to use converts slag to improve soft clay ground. To do this, it was investigated the physical and mechanical properties of the converts slag as a civil construction material. For this, cylindrical cell consolidation with a single vertical drains and large scale soil box test were performed. Through large scale soil box test, the applicability of the converts slag to the present vertical drain techniques which is dependent on sand and plastic drains was studied. As a result of that, it was found that the shape of inserted drains was maintained after completing a consolidation process of a soft clay with slag drains. In addition, we could find that the slag drains showed the similar results with sand drains in soft clay by analyzing the effect of acceleration of consolidation.

• Geomechanics and Engineering
• /
• v.8 no.3
• /
• pp.361-375
• /
• 2015

Constructions over soft and loose soils are one of the most frequent problems in many parts of the world. Cement and cement-lime mixture have been widely used for decades to improve the strength of these soils with the deep soil mixing method. In this study, to investigate the freeze-thaw effect of sand improved by polymers (i.e., styrene-acrylic-copolymer-SACP, polyvinyl acetate-PVAc and xanthan gum) and fly ash, unconfined compression tests were performed on specimens which were exposed to freeze-thaw cycles and on specimens which were not exposed to freeze-thaw cycles. The laboratory test results concluded that the unconfined compressive strength increased with the increase of polymer ratio and curing time, whereas, the changes on unconfined compressive strength with increase of freeze-thaw cycles were insignificant. The overall evaluation of results has revealed that polymers containing fly ash is a good promise and potential as a candidate for deep soil mixing application.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.40 no.2
• /
• pp.123-129
• /
• 1998

Compressibility and permeability properties are the most important input parameters necessary to assess the suitability of core materials in seepage control system construction. To achieve this objective, an experimental investigation was conducted in the laboratory. For the bentonite-soil/sand mixes, consolidation and permeability tests were carried out in the conventional consolidation cell, 6Omm in diameter and 2Omm in height, was modified to perform a falling head type permeability test. From the results, the normalized relationship with respect to void ratio at liquid-limit state $(e_L)$, and the changes of compressibility and permeability for various bentonite-soil/sand mixes were presented. This approach will be helpful in proportioning mixes and predicting corresponding changes in engineering behavior. And it is possible to proportion a mix to arrive at the required compressibility without affecting the permeability.