• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.1-9
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• 2015

In this study, the objective of the study is to evaluate the effect of calcium carbonate powder, produced by the microbial reactions, on the strength of soft ground (sand). To analyze the cementation effects of calcium carbonate powder produced by microbial reactions on the strength of the sand, six different types of specimens (untreated, calcium carbonate, cement, carbonate+cement (1:9, 3:7, 5:5)) were made. The specimen were tested after curing (7 and 28 days). Uniaxial compressive strengths were measured on $D5cm{\times}H10cm$ specimens. Based on the test results, as both the weight ratio and the curing period increase, calcium carbonate, cement, and calcium carbonate+cement specimens showed an increase in the strength. In addition, compared with the strength of the specimen with cement, the strengths of the specimens with mixing ratios of 1:9, 3:7, and 5:5 (carbonate : cement) were found to be 93.5~95.8%, 825.%, 65.2~70.6%.

• Korean Journal of Environmental Agriculture
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• v.25 no.4
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• pp.382-385
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• 2006

To know the effect of water treatment sludge (WTS) as a rice seedling culture soil, rice seeds are sown, germinated and grown on the culture soils mixed with different ratios of WTS to sand (100:0, 50:50, 30:70, respectively), and their growth effects was compared to that of control, commercial culture soil. When WTS is used as a culture soil for rice, the length and weight of the top part of rice seedling somewhat decreased than those of control treatment while their root length and weight in all WTS treatments significantly increased. Although phosphorus and potassium uptake of rice seedling in WTS treatments was slightly decreased, WTS treatment showed to develop root growth which is necessary in the seedling stage of all plane. Such a stimulatory effect on root growth of rice seedling was significant in the mixture ratio of 50% WTS to 50% sand.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1889-1894
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• 2012

A small-scale chamber test laboratory for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. Laboratory test which was simulated during construction stage was conducted. The vertical deflection of 4.43mm to 6.6mm, and the horizontal deflection of 5.49mm to 15.9 mm were measured during backfilling. In case of loading, the vertical deflection of 2.41mm to 8.69mm, and the horizontal deflection of 1.66mm to 2.53mm were measured. Its residual deflections were 1.40mm to 5.93mm for vertical and 1.66mm to 2.53mm for lateral. The vertical and horizontal deflecto of controlled low strength materials were smaller than that of sand backfill. Also, it was same trend for the measured surface settlement.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.607-614
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• 2014

The purpose of this dissertation was to investigate the effect of mineral admixtures, such as fly ash, blast furnace slag powder, meta kaolin and silica fume, on the basic properties and durability of crushed sand shotcrete, selecting a series of shotcrete mixtures with a variable admixture. Compressive strength increased as the content of mineral admixtures increased, specially it was the most effective when using meta kaolin both at sample specimen and core after shotcreting. Rapid chloride ion permeability test and sulfuric acid resistance test showed that both durability increased as the substitute rate of mineral admixture increased. In air void analysis with image analysis, the targeted the spacing factor and specific surface were not satisfied because air-entrained agent was not used.

• Journal of Navigation and Port Research
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• v.35 no.8
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• pp.613-618
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• 2011

Vessels on anchoring are sometimes dragged due to the increased external forces. For preventing the dragging, it is required to enhance the holding power of the anchor. The holding power depends on the type and weight of the anchor and the seabed condition. Especially, the holding power of AC-14 type anchor is known to be 2~2.5 times bigger than that of ASS type anchor. However, these coefficients was determined nearly by the result of the model test, so there is a need to verify that by sea trial. Therefore actual dragging case was analyzed and then compared with the coefficients in use, it was found that the two of them are much alike.

• Journal of the Korean GEO-environmental Society
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• v.16 no.9
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• pp.5-12
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• 2015

A large amount of dredged soils occur in the marine purification project but dredged fine-grained soils have been abandoned as a waste. The standards as filling materials, banking materials, revetment blocks and concrete blocks were surveyed. Through the geotechnical tests of marine dredged fine-grained soils and the alkali-activation reaction, the usability as banking materials, revetment blocks and concrete blocks were analyzed. Dredged sands could be used as banking materials, and dredged fine-grained soils could be used as filling materials. A mixture of dredged fine-grained soils and dredged sands could be used as banking materials. Materials produced by the alkali-activation reaction could be used as a revetment block and a concrete block.

• Journal of the Korean association of regional geographers
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• v.12 no.3
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• pp.339-351
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• 2006

The purpose of this study is to investigate and analyze the relationships between tidal cycles, surface landforms, and sediments of tidal flats and their resident life. The study areas are Uengdo Ri in the Garolim Bay with wide the mud flat, Doou Ri in the Youngwang tidal flat which is developed sand flat and salt field, and Gomso Bay which is developed aquaculture industry. For resident around tidal flats, sea working takes precedence over farming, and main earnings gets from tidal flats. Resident life around the tidal flats is deeply related to tidal cycles, and low water level of spring tide becomes, they are most active and get more earnings than usual day, so it seems to be periodic markets. It is usually developed shellfish aquafarms in the mud flat, the stow net fishery in the sand flat, and salt fields in the mixed flat near the coast. Also a tidal flat has specialization of economic activity, and is divided into salt field and fish-farming in the supratidal zone, shellfish aquafarm in the intertidal zone, and oyster and porphyra culture in the subtidal zone.

• Journal of the Korean Geosynthetics Society
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• v.22 no.2
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• pp.13-21
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• 2023

Mean sea level has recently been rising due to global warming causing coastal erosion. As Korea is peninsula, the land loss due to coastal erosion is critical. An approach in this study is cementing the coastal area using bacteria, which is called microbially induced carbonate precipitation (MICP). This study tried to see how fresh water and sea water work with MICP as a solvent. Ureolytic activity during the MICP reaction was measured with deionized and sea water. A soil column was prepared to evaluate the strength of MICP-treated sand. Sands were treated by MICP with surface percolation method. As the treatmen t style was different with other conventional methods, several methods were proposed to properly evaluate the MICP-treated sand surface. A micro-scale evaluation was performed to assess the mineral structure treated by different solvents. As results, sea water rendered the ureolytic reaction slower. A needle penetrometer worked well to evaluate the MICP-treated sand surface. This study confirmed the utilization of sea water is feasible as the solvent of MICP.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.287-293
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• 2019

Domestic thermal power plant fly ash is at a situation which emissions are increasing every year. Comparing to Fly Ash, Bottom Ash is only 15 %, but it's recycling rate is low, so most of them is being buried in the ground. However, landfill site of every power plant is full, and the construction of a new landfill is difficult. To solve this problem, the best solution is to use Bottom Ash as a landfill of large-scale civil engineering projects. The purpose of this study was to investigate the compression strength behavior characteristics of weak clay and uniaxial compression test to examine the applicability of surface soil solidification method of mixed soils mixed with industrial waste coal ash and weak clay which is buried in bulk. As a result of the test, the fluidity of the Mixed soil with clay + bottom ash + cement was improved to 200 mm at the water content of 91-92 %. The uniaxial compressive strength was also good for the mixed soils (clay + bottom ash + cement) meeting the required strength of 159 kN/㎡ at 28 days. However, the other samples did not meet the required strength. In this study, the prediction equations for the compression strength behavior by cement and curing period were presented.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.106-111
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• 2011

This study was conducted to investigate the effect of the mixture ratio of a soldier fly casts (SFC), compost and cocopeat on the soil physicochemical properties. The mixture ratios of soil amendment were 0%, 3%, 5%, 7% and 10% (V/V) incorporated with sand which met to the USGA particle standard. To analyze the effects of amendments on soil chemical properties, pH and EC were measured. The porosity, capillary porosity, air-filled porosity, bulk density and hydraulic conductivity also measured to analyze the physical properties. Chemical properties were significantly different by mixture ratios of a SFC, compost and cocopeat. Capillary porosity was a factor involved in soil physical properties by blending with a SFC and compost. It was affected on the volume of porosity or hydraulic conductivity. To analyze the correlation of mixture ratio versus to physical characters, the ratios of SFC were significantly different in capillary porosity, air-filled porosity, and hydraulic conductivity. These results indicated that mixing ratios of SFC were affected on soil physicochemical properties such as porosity and hydraulic conductivity of the root zone on the USGA sand green.