• Journal of Korean Tunnelling and Underground Space Association
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• 제24권6호
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• pp.599-615
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• 2022

In order to excavate underground tunnel most safely such as Han river, the slurry shield TBM method is applied to cope with face of high water pressure for many metro projects. In downtown subway project most of excavated soil is discharged externally whereas in road construction excavated soil is used as filling materials so it becomes important factor for success of the project. After excavated soil, weathered rock and soft rock are discharged with bentonite through discharge pipe to slurry treatment plant then those soils are separated in separation plant according to those size. Fine grained soil has been discarded together with filter cake but it is not toxic and can be mixed with coarse aggregate in proper ratio so this study is performed to find use of qualified filling material to meet quality standard. Therefore, in this study, legal standards and quality standards for the utilization of excavated soil of the slurry shield TBM method were examined and test was conducted to derive recycling way for filter cake and aggregate. And a plan for using it as a filling material for road construction was derived. Because bentonite is a clay composed of montmorillonite, and the excavated soil in the tunnel is also non-toxic, disposal of this material can waste social cost so it is expected to be helpful in the underground space development project that carries out the TBM project by recycling it as a valuable resource.

• Journal of Korean Society of Forest Science
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• 제100권4호
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• pp.681-686
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• 2011

The aim of this study was to investigate the distribution of soil biota across forest types and soil depths in Gwangneung Experimental Forest. We selected 5 sites, which are 3 deciduous- and 2 coniferous forests. The abundance of microflora in these areas was analyzed by the phospholipid fatty acid (PLFA) indicators, and the density of mesofauna was measured by the abundance of nematodes and microarthropods. The abundance of soil microflora was higher in the A layer than in the B layer based on the PLFA indicators, but there were no differences between deciduous and coniferous forests. Average density of nematodes was higher in the A horizon than in the B horizon. The density of fungivorous nematodes was higher in the deciduous forests. Mean densities of Collembola and Oribatida were 44% and 42% of microarthropods in soil samples, respectively. The results of microbial PLFA indicators were significantly correlated with the density of their consumers, which reflected that the food web in fungi- and bacteria-based soil developed in this forests. This study suggested that the distribution of soil organisms largely separated by soil depths and was slightly affected by the forest type in the Gwangneung Experimental Forest.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1263-1263
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• 2001

The amounts of organic matter present in soil and the rate of soil organic matter (SOM) turnover are influenced by agricultural management practice, such as rotation, tillage, forage plow down direct seeding and manure application. The amount of nutrients released from SOM is highly dependent upon the state of the organic matter. If it contains a large proportion of light fractions (low-density) more nutrients will be available to the glowing crops. However, if it contains mostly heavy fractions (high-density) that are difficult to breakdown, then lesser amounts of nutrients will be available. The state of the SOM and subsequent release of nutrients into the soil can be predicted by NIRS as long as a robust regression equation is developed. The NIRS method is known for its rapidity, convenience, simplicity, accuracy and ability to analyze many constituents at the same time. Our hypothesis is that the NIRS technique allows researchers to investigate fully and in more detail each field for the status of SOM, available moisture and other soil properties in Alberta soils for precision farming in the near future. One hundred thirty one (131) Alberta soils with various levels (low 2-6%, medium 6-10%, and high >10%) of organic matter content and most of dry land soils, including some irrigated soils from Southern Alberta, under various management practices were collected throughout Northern, Central and Southern Alberta. Two depths (0- 15 cm and 15-30 cm) of soils from Northern Alberta were also collected. These air-dried soil samples were ground through 2 mm sieve and scanned using Foss NIR System 6500 with transport module and natural product cell. With particle size above 150 microns only, the “Ludox” method (Meijboom, Hassink and van Noorwijk, Soil Biol. Biochem.27: 1109-1111, 1995) which uses stable silica, was used to fractionate SOM into light, medium and heavy fractions with densities of <1.13, 1.13-1.37 and >1.37 respectively, The SOM fraction with the particle size below 150 microns was discarded because practically, this fraction with very fine particles can't be further separated by wet sieving based on density. Total organic matter content, mechanical texture, ash after 375$^{\circ}C$, and dry matter (DM) were also determined by “standard” soil analysis methods. The NIRS regression equations were developed using Infra-Soft-International (ISI) software, version 3.11.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.120.1-120
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• 2003

White rot on Allium species recently had a high incidence as increased cultivating areas of tropical garlic types in Korea. Two types of Sclerotium have been known as causal agents producing different size and shapes of sclerotia in infested fields. We developed a new method for isolation of two types of sclerotia from infested field soils that can be used for ecological study of sclerotium spp. and establishment of control strategy. Soil samples collected from heavily infested fields were evenly mixed and placed on a automatic sieve shaker connected with tap water. After 10 min. of shaking, residues on 0.5mm and 0.25mm sieve were separately collected and suspended with 70％ sugar solution, which method floats sclerotia in aqueous layer. Then, floated fraction was carefully separated and mixed with a same volume of 1％ sodium hypochlorite solution to differentiate with organic materials. This method provides direct count of sclerotia under dissecting microscopy.

• The Korean Journal of Mycology
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• 제21권3호
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• pp.235-245
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• 1993

The symbiotic properties of arbuscular mycorrhizal fungi(AMF) such as the absence and/or presence of symbiosis, spore density, and six factors of phycochemical properties of soil were investigated in the rhizosphere of seven sand dune plants and three control plants around Kum river. The infection of AMF was confirmed in all plants. Three genera, nine species of the AMF spores were identified in the sand dune; Ac. scrobiculata, G. aggregatum, G. convolutum, G. diaphanum, G. dimophicum, G. geosporum, G. vesiculiferum, G. tortuosum, S. pachycaulis. All of them were also found in the control, but S. pachycaulis were only separated in the sand dune. In the control, three genera, four species were identified; G. flavisporum, Gi. margarita, Sc. gregaria. Sc. persica. The species specificity was not found between the sand dune plant and AMF. However, the AMF was thought to be correlated with the soil factors. The spore density was stimulated with increase of the organic matter and the nitrogen content, but inhibited with the water content and the phosphorus content. In respect of the seasonal factor, the spore density was increased in the late growth period of plants.

• Analytical Science and Technology
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• 제15권1호
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• pp.67-71
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• 2002

The residual analysis and half-life time of imidazole fungicide prochloraz in soils (silty clay) were investigated by gas chromatography equipped electron capture detector (GC-ECD). The soil samples were extracted acetone/hexane(1:1) solvent and analyzed after separated by $LC-NH_2$ Sep-Pak solid column. Linear sensitivity of standard calibration curve was Y = 268.8600X + 0.0664, $R^2=0.9998$ between 0.05~1.00 ng. The detection limit was 0.02 mg/L and the average recoveries were 94.5~97.3% from the standard additional experiments with 0.10 and 0.40 mg/L. The half-life time was 24.4 days in room laboratory and 7.6 days in the field test soil.

• Korean Journal of Soil Science and Fertilizer
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• 제49권6호
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• pp.813-818
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• 2016

Distribution of clay minerals separated from clay fraction of corn fields in Korea has been investigated along with their characterization. Crystalline phases of the clay minerals were identified by powder X-ray diffraction (XRD) pattern, and their relative chemical compositions were analyzed by X-ray fluorescence spectrometry (XRF). The soils were found to have pH 6.4, organic matter $37.2g\;kg^{-1}$, available $P_2O_5$ $599mg\;kg^{-1}$, respectively, and exchangeable K, Ca and Mg were 1.2, 7.3 and $1.8cmol_c\;kg^{-1}$, respectively. Major primary minerals consisted mainly of quartz and mica, and kaolinite and chlorite were identified as major secondary clay minerals. For most of soils, mica phase was identified to be muscovite rather than biotite. The average contents of $SiO_2$, $Al_2O_3$ and $Fe_2O_3$ were 43.7, 23.6 and 8.8%, respectively, although they were different with the locations.

• Journal of the Korean Geotechnical Society
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• 제19권5호
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• pp.311-317
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• 2003

The swelling index of clayey soil was examined by constant rate of strain(CRS) consolidation test. Four kinds of strain rate were applied during unloading. The strain rates are l/l, l/5, 1/10, l/l 5 of loading. The strain rates during loading are 0.05%/min and 0.03%/min. From the test results using standard consolidometer, the swelling indexes were much similar values in case of 1/5 or 1/10 of the strain rate during loading stage. In the relation between effective stress and excess pore water pressure ratio, it was found that the existence of cross point and the stress level can be separated into two zones according to the swelling index.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.450-452
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• 2004

Using factor analysis and bivariate comparisons of major components in ground water, three geochemical processes were identified as controlling factors of ground water chemistry; 1) natural mineralization by water rock interactions, 2) effect of seawater which includes salinization by seawater near seashores and deposition of sea salt, and 3) nitrate contamination by N fertilization. Contribution of rainfall was also estimated from the measured composition of wet deposition. The geochemical processes were separated using total alkalinity as an indicator for natural mineralization, Cl for effect of seawater, and nitrate for N fertilization. Relatively high correlation of major components with nitrate suggests that nitrification of nitrogenous fertilizers significantly affects ground water chemistry. Total cations derived from nitrate sources have good linearity for nitrate in equivalent basis with a slope of 1.8, which is a mean of proton production coefficients in nitrification of two major compounds in nitrogenous fertilizers, ammonium and urea. Contribution of nitrate sources to base cations, Cl, and SO$_4$ in ground water was determined considering maximum contribution of natural mineralization to estimate a threshold of the effect of N fertilization for ground water chemistry, which shows W fertilization has a greatest effect than any other processes in ground water with nitrate concentration greater than 50 mg/L for Ca, Mg, Na and with concentration greater than 30 mg/L for Cl and SO$_4$.

• Journal of Soil and Groundwater Environment
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• 제7권4호
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• pp.10-16
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• 2002

The multi-aquifer system separated by semipervious leaky beds was analyzed. The finite difference scheme of the Crank-Nicolson method is applied to obtain the solution for this system. The solution of this scheme was compared with the analytical solution for two-layer aquifer systems with one-dimensional steady state. The results showed a good agreement between analytical and numerical solution for two-layer aquifer systems. So, the numerical scheme can be extended to multi-aquifer system. When the pumping is tried for single or multi aquifer, the computation of the groundwater heads was possible for each aquifer in the multi-aquifer with two-dimensional system. So, it might be helpful for the effective groundwater management.