• Earthquakes and Structures
• /
• 제12권2호
• /
• pp.251-262
• /
• 2017

The present research intends to study the effects of the seismic soil-foundation-structure interaction (SFSI) on the dynamic response of various buildings. Two methods including direct and Cone model were studied through 3D finite element method using ABAQUS software. Cone model as an approximate method to consider the SFSI phenomenon was developed and evaluated for both high and low rise buildings. Effect of soil nonlinearity, foundation rigidity and embedment as well as friction coefficient between soil-foundation interfaces during seismic excitation are investigated. Validity and performance of both approaches are evaluated as reference graphs for Cone model and infinite boundary condition, soil nonlinearity and amplification factor for direct method. A series of calculations by DeepSoil for inverse earthquake record modification was conducted. A comparison of the two methods was carried out by root-mean-square-deviation (RMSD) tool for maximum lateral displacement and story shear forces which verifies that Cone model results have good agreement with direct method. It was concluded that Cone method is a convenient, fast and rather accurate method as an approximate way to count for soil media.

• 한국작물학회지
• /
• 제44권2호
• /
• pp.129-133
• /
• 1999

Excessive soil water at vegetative growth stages during the rainy season induces yield losses in soybeans. Our objectives were to obtain basic information about the cultivar differences and to understand the stress-tolerance process for due to excessive soil water. Previous experiments revealed soybean genotypic differences in tolerance to excessive soil water. A field experiment was conducted at the Research Farm of Korea University near Seoul on 21 May 1998. Soybean[Glycine max (L.) Merrill] cultivars, 'Hannamkong' (sensitive) and 'Taekwan-gkong'(tolerant) were planted in vinyl-lined plots(1.2 x 4.2 x 0.3 m deep) and control plots. Drip irrigation began at VI growth stage to submerge the soil surface. Three weeks of excessive soil water treatment reduced all growth parameters measured to soybean plants. Excessive soil water stress resulted in decreases of N, P, K, Ca, Mg and Cu, and increases of Fe and Mn contents in soybean leaves. The stress index of tolerant cultivars under excessive soil water showed no large difference in soybean growth characteristics measured at three growth stages. However, K, Ca, Mg, Fe and Mn contents in soybean leaves appeared to differ between sensitive and tolerant cultivars. From the above results, stress and tolerance indices are proposed for a method to test cultivar differences in plant responses within a species under adverse growth environments.

• Geomechanics and Engineering
• /
• 제21권4호
• /
• pp.337-348
• /
• 2020

Tropical organic soils having more than 65% of organic matters are named "peat". This soil type is extremely soft, unconsolidated, and possesses low shear strength and stiffness. Different conventional and industrial binders (e.g., lime or Portland cement) are used widely for stabilisation of organic soils. However, due to many factors affecting the behaviour of these soils (e.g., high moisture content, fewer mineral particles, and acidic media), the efficiency of the conventional binders is low and/or cost-intensive. This research investigates the impact of different constituents of cement-sodium silicate grout system on the compressibility behaviour of organic soil, including settlement and void ratio. A microstructure analysis is also carried out on treated organic soil using Scanning Electron Micrographs (SEM), Energy Dispersive X-ray spectrometer (EDX), and X-ray Diffraction (XRD). The results indicate that the settlement and void ratio of treated organic soils decrease gradually with the increase of cement and kaolinite contents, as well as sodium silicate until an optimum value of 2.5% of the wet soil weight. The microstructure analysis also demonstrates that with the increase of cement, kaolinite and sodium silicate, the void ratio and porosity of treated soil particles decrease, leading to an increase in the soil density by the hydration, pozzolanic, and polymerisation processes. This research contributes an extra useful knowledge to the stabilisation of organic soils and upgrading such problematic soils closer to the non-problematic soils for geotechnical applications such as deep mixing.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
• /
• pp.213-216
• /
• 2002

To investigate the conditions of groundwater resources in Jeonju, Wanju, and Goksung areas, a basic groundwater survey was performed. From the survey, various useful informations such as groundwater use, waterlevel distribution, water chemistry were obtained. This study focused on the analysis of the water levels, which were automatically monitored with pressure transducers or manually measured. The monitorings were conducted for both shallow wells completed in alluvial aquifers and deep wells in bedrock aquifers. This study presents results of the investigation.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
• /
• pp.385-388
• /
• 2005

Through the regional lineament analysis in Korea peninsula, the statistical distribution of regional lineament is investigated. We also analyze the lineaments pattern using the fractal dimension. These results are the preliminary study for a understanding of the deep ground geological structure in Korea. For the investigations of the average block scale, we use the Dershowitz and Herda(1992)'s method. At result, the average spacing between the regional lineaments is about 10km.

• Geomechanics and Engineering
• /
• 제3권2호
• /
• pp.109-116
• /
• 2011

This note presents an analytical solution for the determination of the shape factor of a flush bottom piezometer in a uniform, isotropic, and incompressible deep soil deposit. The deduced shape factor is compared to published values obtained by approximate methods. Depending on the selected value, the difference may reach 11%.

• 한국토양비료학회지
• /
• 제48권5호
• /
• pp.522-527
• /
• 2015

Decision of available soil depth based on soil physical and hydraulic properties for the $3^{rd}$ Landscape Vegetation Project in the Incheon International Airport was attempted. The soil samples were collected from the 8 sites at different depths, 0-20 and 20-60cm, for the three project fields, A, B, and C area. Physical and chemical properties including particle size distribution, organic matter content and electrical conductivity were analyzed. Hydrological properties including bulk density and water holding capacity at different water potential, -6 kPa, -10 kPa, -33 kPa, and -1500 kPa were calculated by SPAW model of Saxton and Rawls (2006), and air entry value was calculated by Campbell model (1985). Based on physical and hydrological limitation, feasibility and design criteria of soil depth for vegetation and landfill were recommended. Since the soil salinity of the soil in area A area was $19.18dS\;m^{-1}$ in top soil and $22.27dS\;m^{-1}$ in deep soil, respectively, landscape vegetation without amendment would not be possible on this area. Available soil depth required for vegetation was 2.51 m that would secure root zone water holding capacity, capillary fringe, and porosity. Available soil depth required for landscape vegetation of the B area soil was 1.51 m including capillary fringe 0.14 m and available depth for 10% porosity 1.35 m. The soils in this area were feasible for landscape vegetation. The soil in area C was feasible for bottom fill purpose only due to low water holding capacity.

• 농업과학연구
• /
• 제3권2호
• /
• pp.139-144
• /
• 1976

신개간지토양(新開墾地土攘)의 합리적(合理的)인 지력증진(地力增進) 개선방안(改善方案)을 구명(究明)하기 위(爲)하여 7종(種)의 토양개량방법(土壤改良方法)을 처리(處理)하고 대두(大豆)을 재배(栽培)하였던바 그결과를 요약(要約)하면 다음과 같다. 신개간지(新開墾地) 토양(土攘)에서는 pH가 낮고 유기물(有機物)과 인산(燐酸)은 물론 석회(石灰) 마그네슘등(等)의 염기가 부족(不足)하였다. 석회(石灰)와 용성인비(熔成燐肥)는 토양산도(土壤酸度)의 교정효과(校訂效果)가 컷으며 유기물(有機物)의 증가(增加)에 대해서는 퇴비(堆肥)의 효과(效果)가 가장 큰 것과 퇴비(堆肥)와 용성인비(熔成燐肥)는 토양중(土壤中)의 칼슘함량(含量)을 증가(增加)시키는 효과(效果)가 컷으며 석회(石灰) 용성인비(熔成燐肥) 퇴비(堆肥) 및 심경(深耕)모드가 토양중(土壤中)의 고토함량(苦土含量)을 현저(顯著)히 증가(增加)시켰다. 그리고 퇴비(堆肥)는 토양중(土壤中)의 가리함량(加里含量)을 증가(增加) 시키는 효과(效果)가 현저(顯著)하다. 석회용성인비(石灰熔成燐肥) 및 퇴비(堆肥)는 식물체내의 마그네슘함량(含量)의 증가(增加)에 현저(顯著)한 효과(效果)를 나타내었으며 석회(石灰) 및 용성인비(熔成燐肥)는 각각(各各) 종실중(種實重)의 증효효과(增效效果)가 컸다. 3요소(要素) 퇴비(堆肥) 및 석회시용(石灰施用)과 동시(同時)에 심경(深耕)을 실시(實施)한 구(區)에서 최고(最高)의 종실수량(種實收量)을 보였다. 종실수량(種實收量)은 토양산도(土壤酸度), 토양중(土壤中)의 유기물(有機物) 고토함량(苦土含量) 그리고 식물체내의 고토함량(苦土含量)과 현저(顯著)한 정(正)의 상관관계(相關關係)를 나타내었다.

• Journal of Biosystems Engineering
• /
• 제27권1호
• /
• pp.1-10
• /
• 2002

This study was carried out to investigate experimentally the effect of three factors(dynamic load, inflation pressure and number of passes of tire) on soil compaction under the tire. The experiment were conducted with a 6.00R14 radial-ply tire for sandy loam soil using soil bin system. To evaluate the effect of three factors on soil compaction under the tire, the sinkage. density and volume of soil under the tire were measured fur the three levels of dynamic load(1.17kN, 2.35kN and 3.53kN), for the three levels of tire inflation pressure(103.42kPa, 206.84kPa and 413.67kPa), and for three different number of passes(1, 3 and 5). The results of this study can be summarized as follows : 1. As dynamic load, inflation pressure and number of passes of the tire increased, soil sinkage and density increased. and volume of soil decreased. Thus increase in dynamic load, inflation pressure and number of passes of the tire would increase soil compaction. 2. The effect of tire inflation pressure on sinkage. density and volume of soil under the tire was relatively less than that of the dynamic load. Therefore, it was concluded that dynamic load was more important factor affecting soil compaction in comparison to the inflation pressure of tire. 3. The effect of three different factors on sinkage, density and volume of soil decreased as the soil depth increase. Consequently, it was fecund that soil compaction at a shallow depth in soil was larger than that at deep place in soil.

• 대한임베디드공학회논문지
• /
• 제12권5호
• /
• pp.331-341
• /
• 2017

This paper presents the sea-trial results of Crabster CR6000 which is a deep-sea walking robot developed by KRISO in 2016. Crabster CR6000 is designed to inspect deep-sea environment rejecting the disturbance on the silent and calm abyssal area. The sea-trial was conducted at the East Sea and the Philippine Sea on December 2016. The Crabster CR6000 undocked successfully from the Shuttle after touchdown on the sea-bed and walked out on the soft sediment soil of the 4,743m seafloor at the fourth diving in the Philippine Sea. The advanced technologies and capabilities of CR6000 were verified from the operational and functional test conducted in the sea-trial. The experimental data acquired from the sea-trial were summarized and the first experience of the deep-sea walking robot was presented in this paper.