• Smart Structures and Systems
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• 제7권4호
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• pp.319-328
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• 2011

In this study, the measurements of the dielectric constants of soil at 900 MHz and 1 GHz were made to relate those properties to the moisture content of the soil. This study's intention was to use the relationship between the dielectric constant and the moisture content to develop a landslide prediction system. By monitoring the change of the moisture content within the soil using ground penetrating radar (GPR) systems in the field, the possibility of a landslide is expected to be detected. To establish a database for the dielectric constants and the moisture content, the measurements of soil samples were made using both an open-ended dielectric coaxial probe and the GPR. Based on the measurement results, correlations between the GPR and reflector for each frequency at 900 MHz and 1 GHz were found for the dielectric constants and the moisture content. Finally, the mechanism of the measurement device to be implemented in the field is suggested.

• 산업기술연구
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• 제18권
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• pp.77-86
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• 1998

This study is to provide the useful data for the design and construction of the geotechnical engineering works by collecting and analyzing the soil properties of granite soil in the Kangwon Province. Data base was obtained from 92 field sites in the Kangwon province divided into 15 areas based on administration district. Total numbers of data were 478. Correlations between soil constants, especially compaction properties, were obtained by performing statistical analysis. Analyzed results were as follows. 1. Most of granite soil consists of SM and GM based on United Soil Classification System. 2. Mean gravity of granite soil is 2.65 3. High correlations between optimum moisture content and the maximum dry density, plasticity index and liquid limit are obtained. 4. Analyzed results between other soil constants show relatively low correlation. However, they show consistent trends matchable to geotechnical engineering senses.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.315-317
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• 2004

Henry's law constants of trichloroethylene (TCE) and tetrachloroethylene (PCE) in air-aqueous surfactant systems were determined by gas chromatography headspace analysis of closed system. The effect of surfactant type and concentration was investigated.

• 한국수산과학회지
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• 제24권5호
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• pp.356-361
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• 1991

This study was conducted to determine the decomposition rate constants of organic matter and to evaluate the process of regeneration of inorganic nutrients in coastal and open seawater. The mixture solution of glucose and glutamic acid, and night soil were used as the test organic matter. Oxygen uptake of test solution was observed every day for 5 days for evaluation of decomposition rate constants, and nutrient contents were analyzed every day for 40 days. The decomposition rate constants have been determined by Thomas slope method and compared with the values of each waters. The values of rate constants for open seawater and coastal water containing the mixture of glucose and glutamic acid were 0.23/day and 0.21/day, and those containing night soil 0.23/day and 0.20/day, respectively. The difference of decomposition rate constants between test materials was not found and the valus for each seawater was equal to each other. The nitrification process took place after 22 days for open seawater when night soil was added to the waters.

• 한국지반공학회논문집
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• 제18권4호
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• pp.45-53
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• 2002

말뚝의 파동방정식 해석에 사용되는 지반의 동적 물성치를 구하는 방법으로, 표준관입시험에서 얻은 가속도, 하중 파형을 분석하여 이를 얻고자하는 연구들이 기존에 진행되었다. 그러나 기존의 지반 정수 획득 절차는 해의 유일성을 보장하지 못하고 과도한 계산 시간이 소요되거나, 시간 영역에서의 몇 개의 점으로부터 지반 정수를 획득함으로서 전체 파형에 대한 객관성이 부족하다는 단점들을 가지고 있다. 본 논문에서는 전시간 영역에 걸친 획득 파형과 계산 파형의 오차를 최소화하고자 하는 최소 오차법을 기반으로 하여 앞에서 언급한 기존 절차의 단점을 개선한 새로운 지반 정수 획득 방법을 제안하였으며 문헌상에 나타난 계측 자료 및 현장 실측 하중, 가속도 계측 자료를 비교 분석하여 그 적용성을 고찰하였다.

• Geomechanics and Engineering
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• 제25권3호
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• pp.221-231
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• 2021

A two dimensional model of linearly elastic soil spring used for the settlement analysis of the flexible mat foundation is suggested in this study. The spring constants of the soils underneath the foundation were modeled assuming uniformly vertical load applied onto the foundation. The soil spring constants were back calculated using the three-dimensional finite element analysis with Midas GTS NX program. Variation of the soil spring constants was modeled as a two-dimensional polynomial function in terms of the normalized spatial distances between the center of foundation and the analytical points. The Lysmer's analog spring for soils underneath the rigid foundation was adopted and calibrated for the flexible foundation. For validations, the newly proposed soil spring model was incorporated into a two dimensional finite difference analysis for a square mat foundation at the surface of an elastic half-space consisting of soft clays. Comparative study was made for elastic soils where the shear wave velocity is 120~180 m/s and the Poisson's ratio varies at 0.3~0.5. The resulting foundation settlements from the two dimensional finite difference analysis with the proposed soil springs were found in good agreement with those obtained directly from three dimensional finite element analyses. Details of the applications and limitations of the modified Lysmer's analog springs were discussed in this study.

• 아시안잔디학회지
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• 제11권4호
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• pp.303-309
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• 1997

The investigation was cycle of aluminum of surface soil elements in dynamic grassland ecosystems at a steady state in a Zoysia japonica and a Miscanthus sinensis ecosystem in Mt. Kwanak, Korea. Average amounts of total storage for aluminum in Z japonica and M. sinensis grasslands were 8,426mg /$m^2$ and 7,849mg /$m^2$ respectively. Decay constants estimated on the base of experimental and mathematical model, were 0.04 in Z japonica grassland, and 0.08 in M. sinensis grassland. Half time to decay aluminum of litter soils were 17.33 years in Z japonica grass-land, and 8.66 years in Al. sinensis grassland. 95% decay times in Z japonica, and in M. sinensis grassland were 75.0 years and 35.0 years respectively. Needed times to lose almost all of elements in Z japonica and M. sinensis grassland were 125.0 years, and 62.50 years respectively. The metals were losed more rapidly in M. sinensis than in Z japonica grassland. The cycle of aluminum was investigated to be related with soil acidity. Key words: Cycle of aluminum, Zoysia japonica. Miscanthus sinensis, Mt. Kwanak, Decay constants, Soil acidity.

• 한국토양비료학회지
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• 제29권4호
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• pp.328-335
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• 1996

몇 개의 한국 대표 토양과 광물에 대하여 역적정 곡선 자료를 이용하여 표면해리상수의 분포 함수를 계산하였다. 공시 시료의 표면해리 상수는 넓게 분포하였으며, 광물 및 무기질 토양의 표면전하는 해리가 매우 약한 산성으로 나타나고. 유기질 토양에서는 중간정도의 산성을 띄우고 있었다.

• 한국농공학회논문집
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• 제53권6호
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• pp.43-50
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• 2011

The fractal method has recently been applied to a model for determining soil grain size distribution. The objective of this study is to review the applicability of the fractal method for a analysis of submarine sedimentary environments by comparing fractal constants with grain size statistical analysis for the soil samples of Pohang (PH) and Namhae (NH). The y-interception of log (grain size)-log (passing) equation was also used because grain size distribution couldn't be expressed with fractal dimension only. The result of comparison between fractal constants (dimension, y-interception) and grain size statistical indices, the fractal dimension was directly proportional to the mean and the sorting. And the y-interception showed high correlation with the mean. The fractal dimension and y-interception didn't show significant correlation with the skewness and the kurtosis. Thus regression equations between fractal constants and two statistical indices (mean, sorting) were derived. All classifications of the mean and the sorting could be determined using the regression equation based on the fractal dimension and y-interception. Therefore, fractal constants could be used as an alternative index representing the sedimentary environments instead of the mean and sorting.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.68-71
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• 2004

Effects of surfactants and natural organic matter (NOM) on the sorption and reduction of tetrachloroethylene (PCE) and chromate with iron were examined in this study. PCE and chromate reduction by iron depended on the ionic type of the surfactants in this study. The apparent reaction rate constants of PCE with Triton X-100 and hexadecyltrimethyl ammonium (HDTMA) at one half and two times of the critical micelle concentration (CMC) were relatively higher than without surfactants because of the enhanced PCE partitioning and surface concentration. In the presence of sodium dodecyl benzene sulfonate (SDDBS) at 2000 mg/L and NOM at 50 mg/L, the apparent reaction rate constants of PCE increased, but TCE production decreased. The enhanced removal rate of PCE was not due to the dechlorination, and the sorption was dominant iron with SDDBS and NOM. The apparent reaction rate constants of chromate by iron with Triton X-100 and NOM were 1.4-3.1 times lower than without surfactants while that with HDTMA was two times higher than without HDTMA, When the sorbed HDTMA molecules form admicelles, negatively-charged chromate has an affinity for the positively-charged HDTMA head group.