• Journal of the Society of Disaster Information
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• v.8 no.3
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• pp.204-212
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• 2012

Lightweight soils are very economical and environment friendly materials that are valuable in field without wasting construction materials, dredged soils and clay/ silty soils during construction. Recently, the research of lightweight soils mixed with recycled material (recycled tire powder, rice husks) have been investigated. In this study the mix design factors (i.e., weight of soil, water content, foaming agent and added water) were analyzed and optimized mix design was suggested using cement content for revealing strength. For the analysis the stress-strain behavior, strength with respect to time, and experimental strength for the component of recycled material were analyzed. Finally, target strength was determined to calculate reasonable and economical mix ratio and the optimized cement content was suggested.

• Journal of the Korean GEO-environmental Society
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• v.12 no.7
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• pp.31-37
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• 2011

Only a few studies have been conducted using reduced slag as recycled material. The reduced slag in electric furnace is produced as a by-product in making a steel and a few applications of the reduced slag as expensive additives and bonding materials or as the stabilized soils was reported. The purpose of this study is to present the feasibility of the reduced slag as recycled material, especially, in a field of civil engineering. In order to achieve the purpose experiments such as SEM and XRF analysis was conducted for the reduced slag in electric furnace. Based on the results various geotechnical experiments were conducted to know engineering properties of slag-soil mixtures. Weathered soils and clay are mixed with reduced slag for various ratios. As the ratio of reduced slag to weathered soil increases, the maximum dry unit weight of the mixture decreased with increasing optimum moisture content. The results indicates that there is no effect on a reduced slag by compaction efforts. The shear strengths of the weathered soil-slag mixtures are slightly higher or similar to those of weathered soils. The permeability of the weathered soil-slag mixtures is similar to that of silty or sandy soils. Therefore, it is possible to use the mixtures as embankment or backfill materials in the fields. The unconfined strength of the mixtures of reduced slag and clay is higher than that of clay and it tends to increase with the curing time. Therefore it can be used to improve the soft ground.

• Resources Recycling
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• v.27 no.5
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• pp.38-48
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• 2018

Deep cement mixing method (DCM) is used to improve the quality of various ground type and its technical development proceeding based on performance improvements of solidification materials and mixing techniques with ground soil. In this study, it was possible to improve silty clay ground soil had 1 to 3 MPa compressive strength using solidification material that composed mainly circulating fluidized bed combustion (CFBC) power plant fly ash and reduce standard deviation of strengths from over 1.0 MPa to 0.322 MPa using improved auger bits in field test to forming more uniform bulbs than in case of using existing auger bit.

• The Korean Journal of Quaternary Research
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• v.3 no.1
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• pp.35-45
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• 1989

In Korean peninsula as well as in Western European Countries, we can find, reddish bands in sandy deposits of various origin. These bands (called "$B_t$ Band"), composed of fine material, are regularly intervalled and parallel to topography. This study is tring to elucidate their origin and associated milieux, with a group of methods and techniques (field survey, micromorphological analysis, granulometry, X-ray diffractometry of clay minerals...). $B_t$ Bands are not sedimentological origin. They were formed by superposition of two type accumulations in the sandy profile, triggered by different mechanisms: 1) accumulation in banded form, concerning silty heterometric material and micas, oweing to cryophoretic forces operating in course of deep freezing of sandy deposits: 2) illuviation of ferrugineous clays in the precedants bands, migrated in chelate state by soil water. The first processes are associated with very cold and humid climate in which freeze soil more than 3m in depth. The second, cold and humid climate in which podzolizattion is generalized. In case of South Korea and Western Europe, these two types of climates are not present circumstance, but Recent Quaternary (probably since the Wurm).the Wurm).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.286-291
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• 2002

Seedling establishment of soybean [Glycine max (L.) Merr.] is a critical factor in production system and cultural practices. The objective of this study was to identify the components of soybean seedling developments encompassing planting dates and cultivars that respond to emergence, early growth stage and dry matter accumulation. Three soybean cultivars, Hwangkeumkong, Shinpaldalkong 2, and Pungsannamulkong, were planted at Baegsan silty loam soil. Planting date was May 13, June 3, and June 24 in 2001. Sprinkler irrigation was accompanied with 30mm after seeding for three planting dates. Soybean seedlings were sampled at the growth stages from VE to V5. Days to emergence of soybean seedlings were taken 8 at May 13 and 5 at June 24 plantings. Emergence percentage was over 90 at three planting dates. May 13 planting took 33 days and June 24 planting was 25 days for reaching V5 growth stage. Cotyledon number was decreased after V2. Significant cultivar difference was found in cotyledon dry weight until V2 which differed in seed dry weights at the planting times. Leaf and total dry weights of soybean seedlings were not differed from V1 to V3 among planting dates and cultivars. Leaf water contents were generally ranged 78 to 85%. Branch was appeared from V4. Leaf/stem ratio among cultivars was similar at five growth stages and gradually increased from 2.1 at V1 to 2.8 at V5. The results based on this experiment indicated that seedling establishment of soybean was continued from VE to V3 growth stages affecting mainly by planting date and soil moisture.

• Korean Journal of Environment and Ecology
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• v.18 no.2
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• pp.210-220
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• 2004

The purpose of this study is to propose the raw data of conservation and restoration by analyzing the environmental and growth characteristics in Abeliophyllum distichum habitats. The types of soil were sandy loam, loam and silty clay loam and the correlation on chemical characteristics of soil appeared that T-N and C.E.C were highly correlative. In case of growth characteristics, height and diameter in 1st site, crown in 2nd site, number of leaves in 5th site and number of seeds in 4th site were better than other sites. In the results of correlation on growth characteristics, height and diameter were highly correlative. In case of growth and chemical characteristics, EC and height were highly correlative. In the results of regression analysis, R-square of height and EC was some 70.4％ and that of number of leaves and T-N was some 70.2%. To conserve and restore Abeliophyllum distichum habitats, there were demanded that the accurate environmental analysis that considered such diverse factors as light intensity, temperature, genetic quality and so forth.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.157-171
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• 2009

A 151 storey super high-rise building located in an area of reclaimed land constructed over soft marine clay in Songdo, Korea is currently under design. This paper describes the design process of the foundation system of the supertall tower, which is required to support the large building vertical and lateral loads and to restrain the horizontal displacement due to wind and seismic forces. The behaviour of the foundation system due to these loads and foundation stiffness influence the design of the building super structure, displacement of the tower, as well as the raft foundation design. Therefore, the design takes in account the interactions between soil, foundation and super structure, so as to achieve a safe and efficient building performance. The site lies entirely within an area of reclamation underlain by up to 20m of soft to firm marine silty clay, which overlies residual soil and a profile of weathered rock. The nature of the foundation rock materials are highly complex and are interpreted as possible roof pendant metamorphic rocks, which within about 50m from the surface have been affected by weathering which has reduced their strength. The presence of closely spaced joints, sheared and crushed zones within the rock has resulted in deeper areas of weathering of over 80m present within the building footprint. The foundation design process described includes the initial stages of geotechnical site characterization using the results of investigation boreholes and geotechnical parameter selection, and a series of detailed two- and three-dimensional numerical analysis for the Tower foundation comprising over 172 bored piles of varying length. The effect of the overall foundation stiffness and rotation under wind and seismic load is also discussed since the foundation rotation has a direct impact on the overall displacement of the tower.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.1-24
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• 2009

Paleosol layers lying on top of the terrace in Jeongdongjin area appear to have been deposited under generally well-drained condition with periodic waterlogging. From a 4.5m-long profile observed, a total of 6 stratigraphic units were identified. Grain-size analysis indicates the dominance of silty and clay materials with some portions with high sand content. Major mineralogical elements are quartz, feldspar, mica and chlorite. Geo-chemical composition shows little change throughout the stratigraphy with some fluctuation in chemical weathering index. Marked increase in magnetic susceptibility is recognizable where stratigraphic unit changes. Soil- wedge layer is developed around 50cm below the surface with concentration of grains of AT tephra (c. 25,000 BP). An OSL date of c. 110,000 BP was obtained from a sand layer lying below the paleosol.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.140-146
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• 2010

Monitoring of the dynamic changes at paddy rice agriculture is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 260 paddy soil samples every four years from 1999 to 2007 in Gyeongnam Province. Soil chemical properties such as pH, organic matter, available phosphate, silicate, exchangeable potassium, calcium, and magnesium contents were analyzed. The contents of exchangeable cations, and available silicate were significantly increased in 2007 compared to 1999. The chemical contents of organic matter, exchangeable potassium, and magnesium were significantly increased in acid sulfate soil, and silty clay loam compared to those of other soil types, and textures. Especially, content of organic matter was significantly increased in hill area compared to other soil topographies, while exchangeable potassium was significantly decreased. Principle component analysis (PCA) of chemical properties in paddy soils was obtained with eigenvalues > 1 summing 39.1%of variance for PC1, 20.4%of variance for PC2, and 59.5%of the total variance in the all of soil chemical properties. Therefore, principal component analysis is more effective for monitoring from chemical properties of paddy soil.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.332-338
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• 2012

Soil compaction is one of the major problems facing modern agriculture. Overuse of machinery, intensive cropping, short crop rotations, intensive grazing and inappropriate soil management leads to compaction. This study was carried out evaluate of the effects soil texture and different compaction levels within the soil profile on the soybean root growth and productivity. The soybean plants were grown in $21cm{\o}{\times}30cm$ cylinder pots using three different soil textures (clay, fine loamy and coarse loamy) compacted at different compaction levels (1.25, 1.50, 1.75, and 2.00 MPa). Results revealed that soybean development is more sensitive on penetration resistance, irrespective of soil type. Soybean yield and root weight density significantly decreases with increasing levels of soil compaction in both clayey and fine loamy soils, but not in coarse loamy soil. The highest root weight density was recorded in coarse loamy soils, followed by fine loamy and clay soils, in descending order. The root growth by soil compaction levels started to decline from 1.16, 1.28 and 1.60 MPa for clay, fine loamy and coarse loamy soils. Soybean production in the field experiment decreased about 30% at compacted sub-soils compared to undisturbed soils.