• Applied Biological Chemistry
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• v.18 no.3
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• pp.123-144
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• 1975

This study has been carried out to investigate the translocation-illuviation status of iron and manganese, which are striking phenomena in paddy soils, in relation to its morphological characteristics, and to find out a method to identify illuvial layer of iron quantitatively. Determination of active iron and easily reducible manganese content in surface soils of lowland paddy (266 samples) in Korea were conducted. The examination has been made on relationship between morphological, physico-chemical properties of the representative paddy soils (9 series) and iron and manganese content of their horizons. The results are summarized as follows. 1. The poorer the drainage, the higher concentration of active iron and easily reducible manganese were found, and under same drainage condition, the more the sand, the lower the content of them. 2. Irrespective of soil texture and drainage, highly signignificant positive correlation was found between the contents of active iron ($\hat{Y}$) and clay plus silt in surface soils. $$\hat{Y}=0.3929+(0.05352\;X\;clay%)+(0.0001023\;X\;silt%){\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;I$$ No correlation, however, was found between clay content and easily reducible manganese concentration. 3. Significant positive correlation was obtained between active iron ($\hat{Y}$) and total iron (x) content in each profiles of all soil series. Obtained regression equation is as follows; $$\hat{Y}=0.361x-0.480(r=0.651^{**}){\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;{\ldots}\;II$$ On the other hand, easily reducible manganese concentration had a tendency to increase, not significantly, with increasing total manganese concentration. 4. Accumulation of iron and manganese generally can be found in paddy soils, but distinct accumulation was found under moderately well drained fine loamy and clay soils, while surface accumulation occurred under poor drainage without regard to soil texture. 5. Profile description or determination of active iron in each horizon were found to be insufficient to designate illuvial layer of iron. Therefore, identification of illuvial layer of iron based on the ratio of total iron and active iron, and concentration of active iron estimated by the content of clay plus silt (Equation 1 above) was thought to be reasonable. Also, manganese accumulation layer would be estimated by total manganese and easily reducible manganese content and their ratio.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2968-2972
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• 2013

A highly efficient and environmentally benign protocol has been developed for the first time to produce a wide range of biologically active 5-hydroxyindole derivatives using montmorillonite KSF clay as a reusable solid acid catalyst. The use of recyclable clay makes this procedure quite simple, more convenient and cost-effective.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.255-264
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• 2021

Asian dust (Hwangsa) deposited on the surface of the Korean Peninsula is difficult to recognize their existence in mountainous terrain undergoing active erosion and weathering. This study examined Asian dust sediments mixed in soils by analysing clay mineralogy, mineral composition, and microtextures of fine silt (< 20 ㎛) in the alkali feldspar granite area of Seoraksan. The fine silt was composed of detrital particles derived from bedrocks, Asian dust sediments, and their weathering products. Clay minerals of 2:1 structural type, chlorite, amphibole, epidote, and Ca-bearing plagioclase were identified as eolian mineral particles. During the weathering of the bedrock composed of quartz and alkali feldspars, albite was partially weathered to produce small amounts of gibbsite and kaolin minerals. Hydroxy-Al interlayered clay minerals were formed by the exchange and fixation of polynuclear Al cationic species into the interlayers of expandable 2:1 clay minerals dominated by illite-smectite series clay minerals. Contribution of Asian dust to the fine silt of soils was estimated around 70% on the basis of total contents of 2:1 phyllosilicates.

• Ocean and Polar Research
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• v.25 no.2
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• pp.133-145
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• 2003

Deep-sea surface sediments were collected using a multiple corer at 20 stations of Clarion-Clipperton fracture zone in the northeast equatorial Pacific to understand latitudinal and longitudinal variations of geotechnical properties. There was a distinct latitudinal variation of geotechnical properties in the study area. The northern sediments showed finer grain size, lower water content and porosity, higher bulk density and specific grain density, lower liquid limits and plastic limits than their southern counterparts. The northern sediments are classified into inorganic clays of low plasticity (fat clays) on plasticity charts and normal to active clay on activity chart, whereas, the southern sediments are classified into fine-grained, highly-plastic, inorganic and biogenic silt or organic clays on plasticity chart and normal to very active clay on activity chart. When shear strength are considered, the northern sediments were found to be in unconsolidated states, while the southern ones to be normal to over-consolidated states. These latitudinal variations in sediment characteristics are likely caused by differences in productivity of surface water that controls sediment compositions, sedimentation rates, and grain solubility.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.566-569
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• 2005

A novel purification method was developed for producing homoharringtonine from Cephalotaxus koreana, to guarantee high purity and yield. Our simple, efficient procedure for isolating and purifying homoharringtonine from C. koreanabiomass consisted of solvent extraction, synthetic adsorbent treatment, low-pressure chromatography, followed by high performance liquid chromatography (HPLC). The use of active clay treatment and silica gel low-pressure chromatography in the pre-purification process allowed for the rapid, efficient separation of homoharringtonine from interfering compounds and dramatically increased the yield and purity of crude homoharringtonine for high-performance liquid chromatography (HPLC) purification steps compared with alternative processes. Homoharringtonine could be obtained simply with high yield and purity from biomass using this purification method, while minimizing solvent use and the scale and complexity of HPLC operations for homoharringtonine purification. Purified homoharringtonine was identified and characterized.

• Journal of the Korean Ceramic Society
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• v.25 no.6
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• pp.685-693
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• 1988

From leaching of Korean native halloysite with hot sulfuric acid, active species of siliceous aluminosilicate are obtained as residue, which gives the mole ratio of SiO2/Al2O3 10 and substantially removes most acid-soluble impurities. By dissolving the residue in sodium hydroxide at an ambient temperature sodium silicate solution is prepared, this is used for zeolite synthesis as one of starting materials. In order to prepare zeolite Type 4A thereform, addition of a proper aluminum source is made so that the composition of the reactant materials may be of the following mole ratios : Na2O/SiO2=1.2-1.5, SiO2/Al2O3=1.8-2.0 and H2O/Na2O=34-45 By careful control of ageing time and temperature, subsequent crystal growth is induced into microfine zeolite 4A, which gives optimum particle size distributjion being suitable for detergent builder. The zeolite products thus obtained and highly competitive with those from the use of the refined clay in comparison of their calcium exchange capacity, whiteness and particle size distribution. The present method shows a marginal advantage over the existing procedures requiring neitherseparate purification nor calcinating otherwise necessary for the raw clay ores in use.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.35-36
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• 2023

Safety management of steel frame members is a very important part to maintain safety and function. However, precise inspection is not possible for steel frame members due to finishing materials and insulation materials, leading to poor inspection. For steel members, an insulating spray coating method is used for high thermal conductivity. The insulation spray method is not only uneconomical, but also has the disadvantage of spoiling the aesthetics. In addition, VOCs are released from paints used in spraying, so a solution is needed. In this study, heating paint was used to improve the disadvantages of the insulation spray coating method and the high thermal conductivity of steel frame members. In addition to this, in order to reduce VOCs generated from the paint, active clay was added to produce a functional exothermic paint, and then the experiment was conducted. As the amount of activated clay increased, the film thickness increased, and the VOCs emission and thermal conductivity decreased.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.91-100
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• 2007

In most design codes, soils are classified as either sand or clay, and appropriate design equations are used to represent their behavior. For example, the behavior of sandy soils is expressed in terms of the relative density, whereas consistency limits are often used for clays. However, sand-clay mixtures, which are typically referred to as intermediate soils, cannot be easily categorized as either sand or clay and therefore a unified interpretation of how the soil will behave at the transition point, i.e., from sandy behavior when fines are low to clay behavior for high fines content, is necessary. In this study, active natural clays are mixed with sand, and the fines content varied in order to produce different structures, ranging from one state where only sand particles form the soil structure to another where the matrix of fines make-up the structure. While paying attention to the granular void ratio in order to clarify the shear properties of sand-clay mixtures with increasing fines content monotonic, shear tests were performed on isotropically, and anisotropically consolidated specimens. From the test results, it was observed that the monotonic shear strength of sand-clay mixtures is dependent on the granular void ratio.

• Journal of the Korean GEO-environmental Society
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• v.25 no.5
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• pp.29-37
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• 2024

This study aimed to investigate the changes in chemical components that occur when weak clay is mixed with steel slag modified with calcium oxide, and to understand the expression characteristics of compressive strength according to hydrophilicity and curing time. XRF testing, SEM imaging, vane shear strength and uniaxial compressive strength testing were conducted. Calcium (Ca) released from the steel slag increases the Ca content in clay by increasing the number of crystal particles and forming a coating layer known as calcium silicate hydrate (CaO-SiO₂-H₂O) through chemical reactions with SiO₂ and Al₂O₃ components. The weak clay stabilized with steel slag is classified into an initial inactive zone where strength relatively does not increase and an activation zone where strength increases over curing time. The vane shear strength of the initial inactive area was found to be 4.4 to 18.4 kN/m² in the state of the weight mixing ratio Rss 30% (steel slag 30% + clay 70%). In the case of the active area, the maximum uniaxial compressive strength increased to 431.8 kN/m² after 480 hours of curing time, which increased due to the apparent adhesion strength of clay through pozzolanic reaction. Therefore, considering the strength expression characteristics of stabilized mixed clay based on the mixing ratio (Rss) during the recycling of steel slag can enhance its practicality in civil engineering sites.

• Journal of the Korean Applied Science and Technology
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• v.16 no.2
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• pp.135-141
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• 1999

A synthesis of Dimer acid was studied from a tall oil fatty acid. Catalytic activity measured as reactant conversion in a autoclave reactor increase in accordance with the acidity. The optimization of process conditions were tested by an experimental design method. Optimization synthetic conditions of dimer acid and were reaction of tall oil fatty acid during 2 hour at $250^{\circ}C$, used of 7.3 wt% active clay and $1.2{\sim}1.4wt%$ water, and found reation pressure $8{\sim}9Kg/cm^2$. The maximum conversion rate was researched $74{\sim}76%$.