• 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 Korean Institute of Gas
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• v.2 no.1
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• pp.23-27
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• 1998

To protect the underground pipeline from the mechanical damage and to enhance the cathodic protection effect, the river sand has been backfilled traditionally around the buried pipeline. However, river sand became depleted and expensive. One has to seek for the economic alternative materials. Crashed stone is a good candidate for the backfill material. In this study, how much the particle size and shape of the crashed stone can effect on the gas pipeline coating was examined. A series of laboratory and field test was performed. In the Lab, the increasing loads were applied to the coated pipeline surrounded by the crashed stone, where no significant damage was observed.

• 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.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.149-156
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• 2001

Zostera caespitosa Miki has been identified to be distributed along the seacoasts of Korea and Japan. This study was intended to clarify the morphological characters and the habitat characteristics of Korean Z. caespitosa. It was confirmed that Z. caespitosa is distributed along the seacoasts of South, Yellow and East Seas of South Korea. The habitats were located in the bay and port with the depth varying from 2.5 to 5.2 m. The habitats of Z. caespitosa were rather deeper than that of mixed bed with Z. marina. The sediment in the habitats was composed of well-sorted fine sand or muddy sand. Z. caespitosa showed marked differences in several morphological characters among sites. Morphology of Z. caespitosa varied with water depths, grain size and organic contents of sediments. Flowering shoots occurred by water temperature of 6.0∼13.7℃ from January to early April.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4C
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• pp.139-147
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• 2012

In this study, various laboratory tests using bottom ash, which has similar engineering properties with sand, were conducted in order to solve the problem of clogging in granular compaction pile and to address sand supply and demand. In particular, testing was performed to help reduce clogging and minimize voids in a crushed stone compaction pile constructed in soft ground. Based on compaction tests and large diameter direct shear tests, an optimum mixing ratio was determined to be 80:20 (crushed stone to bottom ash) because an 80:20 mixing ratio showed the highest shear strength. Test results showed that as the bottom ash content increased above 20%, internal friction angle decreased. Another test method showed freezing and thawing had little effect when the replacement ratio was over 40%. Therefore, bottom ash mixed compaction piles in soft ground are most economical at a 40% replacement ratio.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.48-58
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• 2002

As a pilot experiment for developing the monitoring system for oil spill from storage tank, previous approach of monitoring contaminated oil from mixed soil sample had the limitation that it cannot reflect the real situations of the contamination. In this study, more realistic contamination condition and water contents were considered. Fluorescence intensity was not affected by water contents. To acquire the stability of media, sand, Ca-bentonite, alumina, Fe-oxide, bead and silica were tested. Only sand was suitable to our system. These results should provide basic information for constructing reliable monitoring system.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.179-184
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• 2008

Silt or clay alluvium fully saturated with water generally shows low resistivity. Sometimes it is believe that the low resistivity layer is considered as good aquifer but this makes problems in the development of groundwater. To overcome this problem, we adopted induced-polarization(IP) method with resistivity method. Laboratory experiments and resistivity/IP field surveys with non-polarization electrodes were conducted for the study. Laboratory experiments shows that the increase of clay contents in the sample mixed with sand and clay give low resistivity and high chargeability. We used this experiment results in the interpretation of resistivity/IP field data which were obtained in riverbank filtration. Finally, the layer which has low resistivity and chargeabilty would be regarded as a good aquifer for the development of groundwater intake.

• 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.18 no.2
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• pp.1-10
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• 2019

This study was intended to evaluate the water permeability and structure for calcium bentonite-sand mixtures to utilize calcium bentonite as a liner. This study conducted physico-chemical properties tests, compaction tests, permeability test and Scanning Electron Microscopy analysis (SEM) analysis. It was found the higher the ratio of calcium bentonite, the lower the dry density with coefficient of permeability, and the higher the optimum moisture content. In particular, SEM analysis was found the higher the ratio of calcium bentonite, the higher the area of the montmorillonite particles. In conclusion, the optimum coefficient of permeability that finds the landfill liner condition (must be less than $1{\times}10^{-7}cm/sec$) was obtained when the ratio of calcium bentonite was 40% or higher. These findings may improve the understanding of the calcium bentonite as a liner. Calcium bentonite shows a similar permeability to sodium bentonite 7% when mixed at 40% or more. Therefore, it is considered that calcium bentonite can be utilized as a liner.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2828-2834
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• 2024

This research intends to recycle bone and incorporate it into concrete for radiation shielding application using Phy-X/PSD software. Cement, sand and granite were mixed in proportion of 0.5 kg:1 kg:1 kg to obtain sample A. Other concretes composing of cement, sand, granite and bone ash was in proportion 0.45 kg:1 kg:1 kg:0.05 kg, 0.1 kg:1 kg:1 kg:0.4 kg and 0.35 kg:1 kg:1 kg:0.15 kg to obtain samples B, C and D respectively. 0.5 water-to-cement (W/C) ratio was adopted throughout the mixes because the control mix contain the normal water quantity for normal hydration of cement. Replacing the bone ash for the cement in the fabricated concretes enhances their densities where the fabricated concretes' density decreased from 2.33 g/cm³ to 2.22 g/cm³ by raising the reinforcing bones fly ash concentration from 0 to 0.15 kg. Additionally, increasing the bones fly ash concentration within the fabricated concretes increases their linear attenuation coefficient (LAC) where the fabricated concretes' μ values at 0.662 MeV reach 0.181 cm^-1, 0.178 cm^-1, 0.174 cm^-1, and 0.171 cm^-1, respectively for concretes A, B, C, and D. The use of other local materials is recommended, as it improves waste management being the major aim of the sustainable development goal.