• Geotechnical Engineering
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• v.12 no.4
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• pp.157-178
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• 1996

Current design methods for reinforced earth structures take no account of the magnitude of the strains induced in the tensile members as these are invariably manufactured from high modulus materials, such as steel, where straits are unlikely to be significant. With fabrics, however, large strains may frequently be induced and it is important to determine these to enable the stability of the structure to be assessed. In the present paper internal design method of analysis relating to the use of fabric reinforcements in reinforced earth structures for both stress and strain considerations is presented. For the internal stability analysis against rupture and pullout of the fabric reinforcements, a strain compatibility analysis procedure that considers the effects of reinforcement stiffness, relative movement between the soil and reinforcements, and compaction-induced stresses as studied by Ehrlich 8l Mitchell is used. I Bowever, the soil-reinforcement interaction is modeled by relating nonlinear elastic soil behavior to nonlinear response of the reinforcement. The soil constitutive model used is a modified vertsion of the hyperbolic soil model and compaction stress model proposed by Duncan et at., and iterative step-loading approach is used to take nonlinear soil behavior into consideration. The effects of seepage pressures are also dealt with in the proposed method of analy For purposes of assessing the strain behavior oi the fabric reinforcements, nonlinear model of hyperbolic form describing the load-extension relation of fabrics is employed. A procedure for specifying the strength characteristics of paraweb polyester fibre multicord, needle punched non-woven geotHxtile and knitted polyester geogrid is also described which may provide a more convenient procedure for incorporating the fablic properties into the prediction of fabric deformations. An attempt to define improvement in bond-linkage at the interconnecting nodes of the fabric reinforced earth stracture due to the confining stress is further made. The proposed method of analysis has been applied to estimate the maximum tensions, deformations and strains of the fabric reinforcements. The results are then compared with those of finite element analysis and experimental tests, and show in general good agreements indicating the effectiveness of the proposed method of analysis. Analytical parametric studies are also carried out to investigate the effects of relative soil-fabric reinforcement stiffness, locked-in stresses, compaction load and seepage pressures on the magnitude and variation of the fabric deformations.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.489-502
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• 2012

Biogeochemical processes in groundwater-stream water mixing zone are recently of great interest because biodegradation and natural attenuation of aquatic contaminants may occur through the processes. The objectives of this study are to investigate the hydrologic and biogeochemical processes at the groundwater-stream water mixing zone through which surface water-driven nitrate may be naturally attenuated, and to examine the effect of the vertical flow exchange flux on biogeochemical processes using correlation analysis. To examine the direction of vertical water flow in the zone, vertical hydraulic gradients were measured at several depths using mini-piezometers. Microbial populations in soil samples of the zone were also analyzed by means of the polymerase chain reaction (PCR) and Cloning methods. In addition, partial correlations among vertical flow exchange, nitrate concentration and microbial activity was investigated to examine their mutual interaction. The results showed the significant interaction among the three parameters, resulting in natural attenuation of nitrate. This study showed an example of the biogeochemical fuction of groundwater-stream water mixing zone, which can be predictable from the examination of the interaction among microbial activities, concentration of contamination and vertical flow exchange flux. temperature show a significant difference in adjacent streambed, Also, the results shows that distribution of temperature was more affected by groundwater direction than intensity of flux.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.137-145
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• 1981

The mutual effects of calcium, potassium and boron on the growth of the leaf lettuce and its following crop of soybean in the granite soil were observed. The results obtained were as follows : 1. The yields of leaf lettuce and soybean were greatly increased by the application of calcium. It was observed that the calcium content in soybean leaf correlated positively with the yields, the number of pods and dry weight of soybean. 2. The application of calcium was effective by itself on the plant growth, the Ca+B application was better effective, and the best effective plot was $Ca+B_1+K_1$. 3. No significant tendency was observed between the Ca/B ratio in plant tissue and its growth. 4. The application of boron increased calcium absorption in plant tissue regardless of the application of calcium. 5. The number of pods and 100 grains weight of soybean were increased by the application of boron, And a positive correlation was observed between the boron content in soybean leaf and the number of pods of soybean. 6. One basal application of calcium, potassium and boron was effective both on leaf lettuce and on its following crop of soybean.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.301-312
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• 2013

Landslides are caused by complex interaction among a large number of interrelated factors such as topography, geology, forest and soils. In this study, a comparative study was carried out using fuzzy relationship method and artificial neural network to evaluate landslide susceptibility. For landslide susceptibility mapping, maps of the landslide occurrence locations, slope angle, aspect, curvature, lithology, soil drainage, soil depth, soil texture, forest type, forest age, forest diameter and forest density were constructed from the spatial data sets. In fuzzy relation analysis, the membership values for each category of thematic layers have been determined using the cosine amplitude method. Then the integration of different thematic layers to produce landslide susceptibility map was performed by Cartesian product operation. In artificial neural network analysis, the relative weight values for causative factors were determined by back propagation algorithm. Landslide susceptibility maps prepared by two approaches were validated by ROC(Receiver Operating Characteristic) curve and AUC(Area Under the Curve). Based on the validation results, both approaches show excellent performance to predict the landslide susceptibility but the performance of the artificial neural network was superior in this study area.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.587-602
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• 2017

Correlations of soil and leaf nutrients and growth of young 'Enterprise' apple (Malus ${\times}$ domestica Borkh.) trees were analyzed with tree damage, such as Japanese beetle (JB; Popillia japonica Newman)-damaged leaves, vole damage to trunk, tree mortality, and weed density in a certified organic orchard in warm and humid environment of Southern USA. Interaction treatments of four mulch and three fertilizers were applied around trees as follows: mow-and-blow (MB), shredded paper (SP), wood chips (WC), and green compost (GC) as a mulch, with no fertilizer (NF), poultry litter (PL), and commercial organic fertilizer (CF) as a fertilizer applied in April. Vole damage to trunk and weed density were little correlated with mineral nutrients and tree growth. JB-damaged leaves were highly stimulated to 26.5% in GC-treated plots while tree mortality were increased by MB treatments. Biomass production per tree was approximately 3,700 g on the WC- and GC-treated plots, which was two times higher than those values observed on the other two mulch plots. JB-damaged leaves tended to get worse when nutrients in soil and leaf increased through the correlation analysis, with a strong positive relationship ($r^2=0.585$) observed between JB-damaged leaves and trunk cross sectional area, a vegetative indicator. Tree mortality was more negatively associated with nutrient contents and growth of trees than those of soil nutrients. Wood chips was considered for a local organic mulch materials to increase organic matter contents and to produce healthy young trees in Southern USA, with control insect, such as beetle, and vole density in an orchard habitat.

• Journal of the Korean Geotechnical Society
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• v.31 no.7
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• pp.13-28
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• 2015

This study extended the Lee et al.'s (2015a) solution which improved the existing analytical solution for prediction of the residual pore water pressure into progressive wave and flow coexisting field. At this time, the variation of incident wave period and wave length should be incorporated to Lee et al.'s (2015a) analytical solution, which does not consider flow. For the case of infinite thickness, the new analytical solution using Fourier series was compared to the analytical solution using Laplace transformation proposed by Jeng and Seymour (2007). It was verified that the new solution was identical to the Jeng and Seymour's solution. After verification of the new analytical solution, the residual pore water pressure head was examined closely under various given values of flow velocity's magnitude, direction, incident wave's period and seabed thickness. In each proposed analytical solution, asymptotic approach to shallow depth with the changes in the soil thickness within finite soil thickness was found possible, but not to infinite depth. It is also identified that there exists a discrepancy case between the results obtained from the finite and the infinite seabed thicknesses even on the same soil depth.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.4
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• pp.221-225
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• 1974

The field experiment was conducted to find out the effect of inoculation of Rhizobium and interaction between amount of nitrogen and inoculating in soybean with 4 replicated split plot design. Main plot was 4 level of nitrogen 0, 2, 6, 12kg/10a and subplot was inoculation and uninoculation. The results are summarized as follows. 1. The yield of soybean did not show any significant difference among nitrogen level or between inoculating but yield of inoculated plot was a little increased than that of uninoculation. 2. At four leaves stage and flowering stage, the weight of nodules in root was decreased with incresing amount of nitrogen significantly and uninoculation caused a reduction compared with modulation significantly and those tendency was same in plant height, and those difference among treatment was more distinct in four leaves stage than in flowering stage. 3. After harvest, total nitrogen content in soil was not only increased with increasing nitrogen level but also was more increased in inoculated plot than in uninoculated plot except nitrogen 0kg/10a level. Inoculation of Rhizobium raised 15kg of nitrogen per l0a at 6kg nitrogen level compared with uninoculation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.214-227
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• 2018

An object oriented crop model was developed to perform crop growth simulation taking into account complex interaction between biotic and abiotic factors in an agricultural ecosystem. A set of classes including Atmosphere class, Plant class, Soil class, and Grower class were designed to represent weather, crop, soil, and crop management, respectively. Objects, which are instance of class, were linked to construct an integrated system for crop growth simulation. In a case study, yield of corn and soybean, which was obtained at an experiment farm in Rural Development Administration from 1984 to 1986, were compared with yield simulated using the integrated system. The integrated system had relatively low error rate of corn yield, e.g., <4%, under sole and intercropping conditions. In contrast, the system had a relatively large underestimation error for above ground biomass except for grain compared with those observed for corn and soybean. For example, estimates of biomass of corn leaf and stem was 31% lower than those of observed values. Although the integrated system consisted of simple models, the system was capable of simulating crop yield under an intercropping condition. This result suggested that an existing process-based model would be used to have more realistic simulation of crop growth once it is reengineered to be compatible to the integration system, which merits further studies for crop model improvement and implementation in object oriented paradigm.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.1
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• pp.71-80
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• 2004

This study was conducted to investigate the effects of the type and application season of animal manure (AM) on herbage productivity, efficiency of nitrogen utilization in mixed grassland. Main plots were the types of AM, such as cattle feedrot manure (CFM), swine manure fermented with sawdust (SMFWS) and cattle slurry (CS). Subplots were the seasons of AM application. such as application in autumn or in spring as single dressing. and application in autumn and spring as a 50:50 split dressing. The results obtained where summarized as follows ; 1. Herbage productivity and nutritive value were hardly influenced by type and application season of AM. 2. Nitrogen efficiency of CFM and CS was lower than that of SMFWS. 3. Organic matter (OM) content in the soil was not significantly different by the type and application season of AM. OM content among AM treatments was the highest with CFM and the lowest with CS. 4. Nitrogen content of the soil was hardly influenced by the type and application season of AM and not affected by the interaction between the type and application season of AM.

• Journal of the Korean Geotechnical Society
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• v.25 no.7
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• pp.35-46
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• 2009

Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of mean normal stress and the increase of coefficient of pullout friction. From laboratory tests, it was found that dilatancy angle could be estimated by modified cavity expansion theory using the measured wall displacements. The radial displacement increases with dilatancy angle decrease and the dilatancy angle increases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the modified cavity expansion theory.