• 한국토양비료학회지
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• 제44권3호
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• pp.517-526
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• 2011

Soil structure plays an important role in ecological system, since it controls transport and storage of air, gas, nutrients and solutions. The study of soil structure requires an understanding of the interrelations and interactions between the diverse soil components at various levels of organization. Investigations of the spatial distribution of pore/particle arrangements and the geometry of soil pore space can provide important information regarding ecological or crop system. Because of conveniences in image analyses and accuracy, these investigations have been thrived for a long time. Image analyses from soil sections through impregnated blocks of undisturbed soil (2 dimensional image analyses) or from 3 dimensional scanned soils by computer tomography allow quantitative assessment of the pore space. Image analysis techniques can be used to classify pore types and quantify pore structure without inaccurate or hard labor in laboratory. In this paper, the last 50 years of the soil image analyses have been presented and measurements on various soil scales were introduced, as well. In addition to history of image analyses, a couple of examples for soil image analyses were displayed. The discussion was made on the applications of image analyses and techniques to quantify pore/soil structure.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.49-59
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• 2021

The effects of green manure crops, hairy vetch and sesban, supplemented with HS (humic substance) on biological soil health indicators was studied in a pot containing two kinds of reclaimed soil previously contaminated with petroleum hydrocarbons; a soil remediated by land-farming (DDC) and another soil by low-temperature thermal desorption (YJ). Treatments include no plant (C), plants only (H), and plants+2% HS (PH), which were evaluated in a pot containing respective soil. Biological indicators include microbial community analysis as well as soil enzyme activities of dehydrogenase, 𝛽-glucosidase, N-acetyl-𝛽-D-glucosaminidase (NAG), acid/alkaline phosphatase, arylsulfatase, and urease. Results showed an increase of enzyme activities in pot soils with plants and even greater in soils with plants+HS. The enzyme activities of DDC soil with plants (DDC_P) and with plants+HS (DDC_PH) increased 1.6 and 3.9 times on average, respectively than those in the control. The enzyme activities YJ soil with plants (YJ_P) and with plant+HS (YJ_PH) increased 1.8 and 3.8 times on average, respectively than those in the control. According to microbial community analysis, the relative abundance of nitrogen-fixing bacteria in DDC and YJ soil was increased from 1.5% to 7% and from 0 to 5%, respectively, after planting hairy vetch and sesban. This study showed that mixed planting of green manure crops with a supplement of humic substance is highly effective for the restoration of biological health indicators of reclaimed soils.

• 한국지반공학회논문집
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• 제29권1호
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• pp.135-147
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• 2013

대부분 사면파괴는 장마기간의 집중호우로 인해 발생하고 있다. 일정시간 강우가 지속되면, 지반의 함수비가 증가되고 모관흡수력이 감소되기 때문에 사면의 안전율은 저하된다. 지하수위 변화로 해석되는 안전율 설계기준은 실제 사면에서 일어나는 현상들을 설명하기에 부족함이 많이 있기 때문에 사면의 관리, 설계, 그리고 시공하는 문제에 있어서 불포화지반의 침투거동을 정확히 예측하여 사면의 불안정성을 평가하는 것이 요구된다. 일반적으로 강우에 의해 사면전체가 포화되는 것이 아니라 강우시간이 지속됨에 따라 얕은 깊이부터 포화되고, 모관흡수력은 급격히 감소한다. 이 상태가 지속되면 지반의 강도가 감소하여 대부분 얕은 파괴 또는 표층파괴 형태로 사면붕괴가 시작된다. 본 논문에서는 전통적인 사면의 건기와 우기시 사면안정해석과 불포화지반의 침투해석을 연계한 사면안정해석을 이론식과 수치해석의 검증을 통하여 포화토와 불포화토의 차이점을 실제 현장사면에 적용하여 비교분석하였다.

• 한국토양비료학회지
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• 제33권3호
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• pp.153-159
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• 2000

토성분석방법으로 사용되고 있는 표준비중계법 (Standard Method ; SM)과 개선비중계법(Simplified for Soil Texture Analysis ; SSTA)및 간이계산법(Simplified Clay Fraction Piocedure;SCFP)간의 $2{\mu}m$ 점토함량을 비교하고자 본 시험을 수행하였다. 사용된 시료는 점토함량이 2~40% 내외의 토양 28점이었다. 현재 국내사용 표준방법은 particle size Distribution을 위한 것이지, 토성판정을 위한 $2{\mu}m$ 점토함량을 계산하는데는 약간의 문제가 있는 것으로 판단되었으며 표준분석법과의 상관을 볼 때는 개선비중계법과 간이계산법 모두 1.0에 가까운 상관계수를 보였으나, 간이계산법의 경우 표준분석 법보다는 $2{\mu}m$ 점토함량이 0~2%정도 높게 평가 되었다. 또한 분석한 시료의 토성판정결과 표준분석법과 개선비중계법은 28점 모두 동일한 결과를 얻었으나, 표준분석법과 비교할 때 간이계산법은 28점중 4점이 다른 토성으로 판정되었다. 그러므로 표준분석법 방법보다는 개선비중계법 방법이 $2{\mu}m$ 점토함량을 측정하는데 더 신속하고 정확한 방법이 될 수 있을 것으로 판단되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.293-300
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• 1999

Soilcrete has been the traditional material for the paving and soft ground improvement techniques. But because the durability is not excellent and the quality is not homogeneous, it has not been used for the various purposes up to date. And because the quality of soilcrete is apt to be changed by the content of water and soil stabilizer, and the kind of soil and soil stabilizer, it is not free of cares. But with the increase of naturally oriented needs for the light traffic road such as pedestrian roads of the garden, golf courses and sidewalks, the cases of soilcrete paving has been increased recently. This study aims at making the reference table of the mix design in accordance with the required design specifications for the soilcrete admixtures by the FGC soil stabilizer by using the statistical experiment method. The treated soil is the clay which are widely spreaded in Korea. As the results of this study we can derive the effective reference mix design table for the clay soil treated by the FGC soil stabilizer in accordance with the compressive strength of 50∼200kg/$\textrm{cm}^2$ soilcrete with respect to the contents of water, soil stabilizer and fine sand.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.405-408
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• 2002

The electrical conductivity, EC is a major indicator of soil salinity. Measuring EC of saturation-paste extract of soil, ECe, is the standard way to evaluate soil salinity. However much of the data on soil salinity have been obtained by measuring the EC of the 1:5 soil-to-water extract, EC(1:5) or salts contents(%) which multiplied by conversion factor. And, thus we attempted to collect and analysis 90 soil samples at 9 reclaimed tidelands in Korea and to derive a relationship between ECe and dilution factor at ECe and EC(1:5), $DF_{1:5}$ of 3 soil textural conditions and 6 salinity conditions. Regression equations between ECe and $DF_{1:5}$ were obtained $ECe=1.4701ln(DF_{1:5})+5.0974(r^2=0.97^{**})$ in case of more than 50% silt contents, $ECe=2.1399ln(DF_{1:5})+5.3462 (r^2=0.99^{***})$ in case of below 50% silt contents, and $ECe=1.5927ln(DF_{1:5})+5.2486 (r^2=0.98^{***})$ in all cases, and then we suggested the $DF_{1:5}\;and\;DF_%$ of 3 soil textural conditions and 6 salinity conditions.

• Journal of the Korean Wood Science and Technology
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• 제44권2호
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• pp.231-240
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• 2016

The change in chemical compositions of leachate and medium density fiberboard (MDF) from a laboratory-scale simulated landfill which constructed in a plastic container containing alternating layers of soil and MDF was investigated to evaluate decomposing of MDF in soil. Four treatments were conducted: 1) MDF in soil, 2) MDF only, 3) cured UF resin in soil, and 4) soil only. Molecular weight (MW) distribution of compounds in leachate from soil only treatment did not change over time. In UF resin in soil treatment, the MW distribution shifted to a lower MW distribution over time, while the peak shifted to the left indicated changing to higher MW distribution in leachate from treatment 1 and 2 contained MDF. Higher percent nitrogen in leachate was observed in MDF containing treatments due to the UF resin in the MDF. The percent carbon slightly increased in MDF only while that greatly decreased in MDF in soil treatment maybe due to bacterial activity. The percent of extractable materials from the MDF decreased greatly on day 35 compare to day 0, and subsequently did not change much on day 77. In contrast, percent holocellulose and lignin did not change much over time. No structural change of the wood fiber in MDF occurs during the study. Water-soluble materials from MDF in soil contributed the change in chemical composition of leachate.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권3호
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• pp.83-91
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• 2015

Mine soil contamination by high levels of metal ions that prevents the successful vegetation poses a serious problem. In the study presented here, we used the microbial biocatalyst of urease producing bacterium Sporosarcina pasteurii or plant extract based BioNeutro-GEM (BNG) agent. The ability of the biocatalysts to bioremediate contaminated soil from abandoned mine was examined by solid-state composting vegetation under field conditions. Treatment of mine soil with the 2 biocatalysts for 5 months resulted in pH increase and electric conductivity reduction compared to untreated control. Further analyses revealed that the microbial catalysts also promoted the root and shoot growth to the untreated control during the vegetation treatments. After the Sporosarcina pasteurii or plant extract based BNG treatment, the microbial community change was monitored by culture-independent pyrosequencing. These results demonstrate that the microbial biocatalysts could potentially be used in the soil bioremediation from mine-impacted area.

• Geomechanics and Engineering
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• 제12권2호
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• pp.239-255
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• 2017

Various centrifuge model tests on the pile foundations were performed to investigate fundamental characteristics of a pile-soil-foundation system recently, but it is hard to find numerical analysis results of a pile foundation system considering the nonlinear behavior of soil layers due to the dynamic excitations. Numerical analyses for a pile-soil system were carried out to verify the experimental results of centrifuge model tests. Centrifuge model tests were performed at the laboratory applying 1.5 Hz sinusoidal base input motions, and nonlinear numerical analyses were performed utilizing a finite element program of P3DASS in the frequency domain and applying the same input motions with the intensities of 0.05 g~0.38 g. Nonlinear soil properties of soil elements were defined by Ramberg-Osgood soil model for the nonlinear dynamic analyses. Nonlinear numerical analyses with the P3DASS program were helpful to predict the trend of experimental responses of a centrifuge model efficiently, even though there were some difficulties in processing analytical results and to find out unintended deficits in measured experimental data. Also nonlinear soil properties of elements in the system can be estimated adequately using an analytical program to compare them with experimental results.

• Earthquakes and Structures
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• 제18권6호
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• pp.667-675
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• 2020

The current study compares the effect of structure-soil-structure interaction (SSSI) on the dynamic responses of adjacent buildings and isolated structures including soil-structure interaction (SSI) with the responses of fixed-base structures. Structural responses such as the relative acceleration, displacement, drift and shear force were considered under earthquake ground motion excitation. For this purpose, 5-, 10- and 15-story structures with 2-bay moment resisting frames resting on shallow foundations were modeled as a group of buildings in soft soil media. Viscous lateral boundaries and interface elements were applied to the soil model to simulate semi-infinite soil media, frictional contact and probable slip under seismic excitation. The direct method was employed for fully nonlinear time-history dynamic analysis in OpenSees using 3D finite element soil-structure models with different building positions. The results showed that the responses of the grouped structures were strongly influenced by the adjacent structures. The responses were as much as 4 times greater for drift and 2.3 times greater for shear force than the responses of fixed-base models.