• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.5
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• pp.93-98
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• 1999

The results of an experimental investigation on the characteristics of compaction and compressive strength of polypropylene fiber reinforced soil are presented in this paper. This study has been performed to obtain the physical properties of PFRS(polypropylene fiber reinforced soil) such as strain-stress relationships, OMC(optimum moisture contents) and ${\gamma}$dmax (maximum dry unit weight), with four different contents (i.e., 0.1%, 0.3%, 0.5% and 1.0% weights ) of mono-filament and fibrillated polypropylene fibers. From the compaction test results, it is found that OMC increased with the contents ratio of fiber, but ${\gamma}$dmax decreased. It means that the improvement of the workability and the reduction of the weight of embankment structures by the asddtion of the polypropylene fiber. And, from the compression test results, it is found that the additon of the polypropylene fiber remarkably improved the compressive strength of PFRS. And it was observed in the viewpoint of strength that the fibrillated polypropylene fiber reinforced soil is more effective than the mono-filament polypropylene fiber reinforced soil.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.99-106
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• 2008

With globally increasing interests in climate-soil-vegetation system, a new stochastic model of soil water and plant water stress is derived for better understanding of the soil water and plant water stress dynamics and their role in water-controlled ecosystem. The steady-state assumption is used for simplifying the equations. The derived model is simple yet realistic that it can account for the essential features of the system. The model represents the general characteristics of rainfall, soil, and vegetation; i.e. the soil moisture constitutes the decrease form of the steady-state and the plant water stress becomes increasing with the steady state when the rainfall is decreased. With this model, further deep study for the effects of soil water and plant water stress on the system will be accomplished.

• Geotechnical Engineering
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• v.2 no.1
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• pp.7-14
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• 1986

The structure of the collapsible soils, such as decomposed granite soil and loess, were examined by the odeometer test, SEM & XES analysis and static & cyclic triaxial test, and hove this structure have influences upon the collapsible behaviour under static and cyclic load was investigated. The study results obtained are as follows; 1. The macropores space of decomposed granite soil (rd=1.50g/cm3) and loess (rd=1.43g/cm3) used in this test were well developed, and showed the behaviour of collapsible soil. 2. Collapsible soil has high resistance on the strain under natural moisture content, however, the resistance on the strain was sharply decreased by the absorption and increasing load since its special structure was destructed. 3. Under the static load, the strain of collapsible soil was high by the viscous flow of the cyclic bonds with time lapse, but Infer the cyclic load, the strain of collapsible soil was low since the tinge needed to destruct the bonding force of clay was not enough. 4. The understanding about the cyclic behaviour of collapsible soil may be helpful to predict the elastic & residual strain of the foundations by the earthquake together with the damage by the additional failure.

• Journal of Environmental Science International
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• v.28 no.6
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• pp.545-552
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• 2019

Tropaeolum majus, with a high decorative and food demand for vertical greening systems, has been utilized to revitalize urban agriculture. The effects of number of non-woven fabrics in a non-water environment and the adaptability of T. majus to this system were investigated. Planting ground composition of the container-type wall vertical greening system was made using non-woven fabric in one, two, three, or four layers. The results showed that the soil water content remained the highest when the non-woven fabric comprised 4 sheets. The morphological properties showed more growth with the 4 sheets than with 1, 2, and 3 sheets. In terms of physiological characteristics, chlorophyll content was mostly high in the 4 sheets, while shoot fresh weight value was in the order of 3 > 4 > 2 > 1 sheet, and root fresh weight value was in the order of 4 > 2 > 1 > 3 sheets. The dry weight of the measured values in the shoot was in the order of 4 > 3 > 2 > 1 sheet while no clear difference was found in the root of each treatment. The difference in the flowring characteristics was not different, but in evaluating the characteristics as a whole, the growth in the three layers of non-waven fabric was the best. In addition, the soil moisture contents and the growth characteristics were statistically significant as a positive correlation between the groups. Thus, greater the non-woven fabric, the higher is the adaptability of T. majus to dry stress under soil water-free conditions by maintaining soil moisture content. This showed that it represented an effective alternative as a method of vertical greening system for lower maintenance urban agriculture.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.297-306
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• 2019

Soil moisture monitoring is an important task to cope with climate change, and soil water prediction can provide large-scale soil moisture information. Therefore, this study was conducted to evaluate the relationship between the measured and predicted soil water content, and to estimate the correlation between the soil characteristics and soil water content. The selected sites in soil moisture monitoring network were 76, and the soil with high sand content (sand, loamy sand, and sandy loam in soil texture) accounted for 77% of the total. Organic matter and bulk density were 0.03 to 3.50% and 1.01 to 1.69 Mg m^-3, respectively. Predicting values of field capacity and wilting point were lower than the measured soil water content, and the correlation coefficient between the measured and predicted values were low as 0.548 to 0.748. However, a significantly high positive correlation (p<0.01) found between the measured and predicted soil water content. Soil water (field water capacity and wilting point) content was highly positively correlated with silt, clay, and organic matter (p<0.01) and highly negatively correlated with sand (p<0.01).

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.2
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• pp.43-53
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• 2024

This study attempted to elucidate the ecological niches and influencing environmental factors of Quercus variabilis and Quercus acutissima, which are representative deciduous broad-leaved trees in Korean forests, taxonomically close and genetically similar, under climate change conditions. Under climate change conditions induced by increased CO₂ and temperature, soil moisture and nutrient environments were manipulated in four gradients. At the end of the growing, plants were harvested to measure growth responses, calculate ecological niches, and compare them with those of the control. Eperimental plants were grown for 180 days in a glass greenhouse designed with four gradients each for soil moisture and nutrient environments under climate change conditions induced by increased CO₂ and temperature. After harvesting, growth responses of leaf traits were measured, ecological niches were calculated, and these were compared with those of the control groups. Furthermore, the responses of the two species' populations were interpreted using principal component analysis(PCA) based on leaf trait measurements. As a result, under climate change conditions, the ecological niche breadth for moisture environment was broader for Quercus variabilis than Quercus acutissima, whereas for the nutrient environment, Quercus acutissima exhibited a broader niche breadth than Quercus variabilis. And the rate of change in ecological niche breadth due to climate change decreased for Quercus variabilis in both moisture and nutrient environments, while for Quercus acutissima, it increased in the moisture environment but decreased in the nutrient environment. Additionally, in terms of group responses, both Quercus variabilis and Quercus acutissima expanded their ecological niches under climate change conditions in both soil moisture and nutrient conditions, with Quercus acutissima exhibiting a broader niche than Quercus variabilis under nutrient conditions. These results indicate that the changes in leaf morphological characteristics and the responses of individuals reflecting them vary not only under climate change conditions but also depending on environmental factors.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.31-40
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• 2022

Background: Plant vegetation appears in heterogeneous and patchy forms in arid and semi-arid regions. In these regions, underneath the plant patches and the empty spaces between them are covered by biological soil crusts (moss, lichen, cyanobacteria, and fungi). Biological soil crusts lead to the formation and development of fertile islands in between vegetation patches via nitrogen and carbon fixation and the permeation of runoff water and nutrients in the soil. Results: The present study has investigated the association of biological soil crusts, the development of fertile islands, and the formation of plant patches in part of the Takht-e Soltan protected area, located in Khorasan Razavi Province, Iran. Three sites were randomly selected as the working units and differentiated based on their geomorphological characteristics to the alluvial fan, hillslope, and fluvial terrace landforms. Two-step systematic random sampling was conducted along a 100-meter transect using a 5 m² plot at a 0-5 cm depth in three repetitions. Fifteen samplings were carried out at each site with a total of 45 samples taken. The results showed that the difference in altitude has a significant relationship with species diversity and decreases with decreasing altitude. Results have revealed that the moisture content of the site, with biocrust has had a considerable increase compared to the other sites, helping to form vegetation patterns and fertile islands. Conclusions: The findings indicated that biological crusts had impacted the allocation of soil parameters. They affect the formation of plant patches by increasing the soil's organic carbon, nitrogen, moisture and nutrient content provide a suitable space for plant growth by increasing the soil fertility in the inter-patch space.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.217-231
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• 2018

Clayey soils with swelling and shrinkage characteristics have been major causes for many problems in roads, buildings and other civil engineering infrastructure in various areas of Pakistan, particularly where there are several patches of such soils on either side of Indus River. As the consistency characteristics are directly related with the variation of moisture content; therefore, this study was explicitly focused to investigate the effect of lime and wheat straw on the consistency characteristics of clayey soils with relatively high swelling and shrinkage characteristics. The consistency test results indicate that by the increase in lime content there is a decrease in the plasticity index of soil; for instance, 10% lime content resulted to 59% decrease in the plasticity index value. On the other hand; the addition of wheat straw resulted in a significant increase in the plasticity index; for instance, 10% wheat straw content resulted to a 120% increase in the plasticity index. This study has further shown that the shrinkage and swelling of clayey soils which resulting to several problems in the civil engineering infrastructures may adequately be managed through mixing an appropriate amount of lime and wheat straw as soil stabilizing agent for both immediate and long-term effects.

• Korean Journal of Environment and Ecology
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• v.12 no.3
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• pp.236-241
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• 1998

This study was to compare soil characteristics among Quercus mongolica communities that characterize the boreal-temperate deciduous forest in Korea. The classification of Quercus mongolica community and soil sampling were carried in Mt. Odae and Mt. Jungwang in Kangwondo from April of 1991 to October of 1994. The study area was classified as 5 Quercus mongolica communities with Braun-Blanquet method as follows; Quercus mongolica - Abies nephrolepis, Quercus mongolica - Acer pseudosieboldianum, Quercus mongolica - Lindera obtusiloba, Quercus mongolica - Acer mandshuricum, and Quercus mongolica - Carpinus cordata communities. Quercus mongolica - Abies nephorolepis community had the most shallow depth of A horizon(5cm) among communities, and root penetration was mainly from 0 to 10cm soil depth, and they had a dry soil moisture condition. Depth of A horizon of Quercus mongolica - Lindera obtusiloba and Quercus mongolica - Acer mandshuricum communities was about 20cm, and root penetration was mainly from 0 to 20cm soil depth, and they had a slightly dry soil moisture condition. Quercus mongolica - Acer mandshuricum, and Quercus mongolica -Carpinus cordata communities had the deepest depth of A horizon(35cm) and root was well developed over 45cm, and they had a moderately-slight dry soil condition. The soil organic matter, total N, exchangeable Ca, Mg and K concentration and CEC was the greatest in Quercus mongolica-Acer mandshuricum community and Quercus mongolica-Carpinus cordata community among communities. Quercus mongolica - Abies nephyolepis community had the smallest soil organic matter, total N, and CEC among communities. There were large differences among Quercus mongolica communities by soil properties and the result may be due to different habitat positions in the landscape among communities.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.116-121
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• 1999

When plate anchors are embedded in soft clay, they may undergo a deformation under the pressure of sustained load. The critical depth at which the transition from a shallow to a deep anchor takes place depends on the properties of soil. Laboratory model tests were performed for the short-term net ultimate uplift capacity of a circular anchors with respect to various embedment depths and moisture content in saturated kaolinite. The tests have been conducted with the anchor at two different moisture contents. Based on the model test results, empirical relationships between the net load, rate of strain, and time have been developed. In creep tests of kaolinite for load versus ultimate uplift capacity, the displacement of plate anchors rapidly increases during the primary stage but thereafter becomes constant over a period of time.