• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.5-14
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• 2010

This study was aimed to suggest reliable information of shear strength characteristics due to change of saturation in the landfills or slopes during rainfall infiltration. According to the Mohr-Coulomb failure criteria, the characteristics of shear strength due to change of saturation were analyzed for the weathered residual soils which were sampled in the road construction site of Daejeon city. From the direct shear strength tests, the cohesions and the shear resistance angles were showed maximum values in the condition of optimum moisture content, and then decreased in the condition of wet side compaction. In this study, the cohesions were decreased more than 50% according to increasing saturation by infiltration for the compaction soils. But the reductions of the shear resistance angles were about $1{\sim}2^{\circ}$ which was small value, and thus the changes of the saturation were not nearly influenced the shear resistance angle. The influences of the saturation were seemed to very small for the residual strength parameters according to Mohr-Coulomb failure criteria.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.215-224
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• 2019

According to the recent civil engineering construction work site which is a complex process, development of multi-functional geotextiles is required. In this study, the characteristics of five different modified cross-section fiber yarns for the selection of wicking yarns were analyzed and yarns that can achieve target properties were selected. Experimental prototype geotextiles suitable for horizontal wicking drain property and reinforcement was developed and its tensile strength, 2% secant modulus, vertical water permeability, AOS, friction characteristics by the direct shear method, and vertical/horizontal wicking test were analyzed. These tests are conducted to verify the performance of the geotextiles with horizontal wick drain property, separation and reinforcement developed in this study. As a results of the indoor soil box test, it was confirmed that the geotextiles using the wicking yarn sufficiently exhibited the function of discharging excess pore water in the horizontal direction.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.49-55
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• 2016

Field measurement units and a system were constructed and installed in a waste-dump slope at the Imgi mine to investigate and analyze the variations in the unsaturated characteristics of the soil. The field instrumentation system was composed of a data acquisition system (DAS), a solar system, and measuring sensors. The rainfall, matric suction, and volumetric water contents were continuously measured from the units in the instrumented site. The variations in matric suction and volumetric water content were primarily affected by the rainfall intensity. At the surface of the slope, the largest increase and decrease in the changes in matric suction and volumetric water content were observed during the wetting and drying processes, respectively. Also, the matric suction and volumetric water content were 5-35 kPa and 0.12-0.24, respectively. However, the ground water level was not suddenly increased just after rainfall but gradually increased after 2 or 3 days later.

• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.5-15
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• 2004

SIP has been widely used as a low noise and vibration piling method in Korea. But the quality control of SIP was not properly settled down and field workers did not fully understand the principle of SIP method. So not a less troubles were raised at construction site and bearing capacity was not fully mobilized. To settle these problems, Korea National Housing Corporation amended the construction and load test criteria of SIP in 2002. After load tests on the SIPs installed in field according to the new criteria, we found that the bearing capacity in field vs the design load ratio increased and bearing characteristics was enhanced than that installed by the former criteria. To consider the enhanced bearing characteristics in the pile design and determine the adequate design criteria, this paper analyzed the accuracy of design criterion which were commonly used in Korea comparing with the load test results. Analysis result shows that Meyerhof criteria(1976) properly simulates the bearing capacity of SIP installed by the new construction and load test criteria.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.511-517
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• 2013

The Field Velocity Probe (FVP) has been widely applied to determine the various characteristics of soils. This study seeks to estimate soil consolidation characteristics using an FVP and to increase its application in the field. The specimens were extracted from depths of 3 and 6 m at the study site, an area of soft clay in Incheon. In laboratory testing, the specimens were placed in an improved oedometer cell to measure shear wave velocity, and statistical analysis was performed to compare the results of effective stress and shear wave velocity. FVP enables increased resolution in the field because it measures the shear wave velocity every 20 cm. To estimate the condition of consolidation, we compared the results of shear wave velocities between those obtained in the laboratory and those in the field. The field conditions are used to analyze overconsolidated and normally consolidated soils at depths of 3 and 6 m, respectively. The results show that FVP is a suitable method for estimating the degree of consolidation.

• Korean Journal of Pharmacognosy
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• v.38 no.2 s.149
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• pp.157-163
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• 2007

Trillium tschonoskii Maxim. is a kind of 64 endangered plant species designated by the Ministry of Environment in Korea. It is very a rare native plant throughout the country. Therefore, this study was conducted to investigate the native T. tschonoskii in Ulleung Island for their distribution and ecological characteristics. They were mostly distributed valley, mid-slope of the mountain from 186 to 458 m altitude. They had a little low light conditions as they faced west, north west, south west, south-south west, north-north east and east-east north. They were provided with slightly humid condition. Aerial humidities of these quadrates were variable as 21.5-71%. They were located on the variable slopes of 5 to 43 degrees. Soil humidity was slightly dry. Native sites were semi-shaded because tree layer such as Tilia insularis, Zelkova serrata, okamotoanum etc.and sub-tall tree layer such as Ligustrum foliosum, Comellia japonica, Tilia insularis, Callicarpa japonica and so on were grown near by. Woody plants such as A. Okamotoanum, Sorbus commixta, Fagus japonica var. multinervis etc. were frequently observed. These environmental conditions were suitable that T. tschonoskii grows up naturally because of high Percentage as 52.78% of blooming individuals in this study. These native sites were classified with three communities, T. tschonoskii-Majanthemum dilatatum community, T. tschonoskii-Anthriscus sylvestris community and T. tschonoskii-Hepatica maxima community in accordance with altitude and aerial humidity. The best way ffr the preservation of T. tschonoskii habitats and maintainance of its recent population is maintained in recent environmental condition and ecological condition without any management by human-being.

• Journal of Korean Society of Rural Planning
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• v.22 no.4
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• pp.171-182
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• 2016

Since FAO introduced the Globally Important Agricultural Heritage Systems(GIAHS) in 2002, 36 sites of 15 countries so far have been listed on GIAHS. This study aims to find the important agricultural heritages of Korea and to prepare the methods for them to be selected as GIAHS. We have analyzed the proposals of the 36 GIAHS listed in order to study the characteristics of their components of the agricultural heritage which worked for being selected. To analyze the components of the agricultural heritage first, agricultural heritage was classified into 13 types and 42 components in light of GIAHS criteria. Then central themes were set to analyze the relevant contents in the proposals. They were, the type of GIAHS Site, significant agricultural landscape, the agriculture-forestry-fisheries-livestock linkage systems, the multi-layered, inter-cropping, circulation cultivation systems, the soil and water management systems, the conservation of agrobiological diversity and genetic resources, the history of the agricultural heritage, the succession of traditional farming techniques, the cultural diversity and so on. Most GIAHS are located in mountains, grasslands, rivers and coasts, desert than in plains, through which GIAHS assure us that it is the heritage of human challenge to overcome the harsh geographic environment and maintain a livelihood. In these sites the traditional farming techniques are carried on, such as mountain clearings, terraced rice paddies, and burn fields, and the unique irrigation systems and agricultural landscapes are well maintained, and the eco-friendly traditional farming techniques utilizing abundant forest resources and agriculture are well handed down. The origin or home of crop growing, a variety of genetic crop storage, the world's largest crop producer and preserving cultural diversity are also important factors for the selection.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.98-105
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• 1997

Compacted clay materials are often used to form barriers for waste disposal by means of landfill. The performance of clay barrier depends on its permeability characteristics under the site environments. The study discusses permeability characteristics of 4 types of permeants through a compacted clayey soil. Permeabilities are measured using the modified rigid-wall permeater and with water, PEG, Ethanol, and TCE, ranging 80 to 3.4 of dielectric constants. Results of the study are as follows : 1) Absolute permeabilities of Ethanol and TCE that their dielectric constants are lower than that of water are $K=1.0{\times} 10^{-12} cm^2$, and $5.8{\times} 10^{-12} cm^2$, respectively, that is, 1.67, and 9.67 times of permeability of water, respectively. Absolute permeability and dielectric constant of water are $K=6{\times} 10^{-13} cm^2$, and 80, respectively. 2) Changes in absolute permeability of Ethanol and TCE converge to a constant after 3.5 pore volume of permeant flows through the clay sample. This can be explained that diffuse double layer of clay is no longer reacted with permeants and contracted their pores. However there is no change in absolute permeability when water is used as a per-meant. 3) It is found that absolute permeability in reversely proportional to the value of dielectric constant of the permeants. Change in absolute permeability of the permeants with 40 or over of dielectric constant is not significant. However change in absolute permeability of the permeant with 30 or lower dielectric constant is abruptly increased. 4) A lower absolute permeability of PEG is found because of its high viscosity.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.6
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• pp.39-45
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• 2016

In this paper, analyzes the characteristics of self-weight consolidation on the dredged clay according to the fines content and falling height. Research was performed with the dredged clay sampled by Sae-mangeum field site. Classification of fines content was performed by sieve analysis test. After adjusting the fine content, self-weight consolidation tests were carried out focussing on the variation of fines content and falling heights. From the test results of the self-weight consolidation test, samples with high fines content had reached sedimentation completion more later than ones with less fine content samples. In other words, the start of self-weight consolidation was slowing down with increasing of fines content. Also, from the test results of calculating the coefficient of sedimentation consolidation, the coefficient value were increased with the fines content increases. In addition, the change of sedimentation ratio and volume ratio showed more higher changed value as the fine content increases. Thus, it is important to consider the fines content when estimate the settlement time of dredged soil in field dredge work.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.5
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• pp.25-33
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• 2011

In the nonlinear response history analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structural systems. As the properties of the ground motion, using time history analysis, are interrelated with many factors such as the fault mechanism, the seismic wave propagation from source to site, and the amplification characteristics of the soil, it is difficult to properly select the input ground motions for seismic response analysis. In this paper, the most unfavourable real seismic design ground motions were selected as input motions. The artificial earthquake waves were generated according to these earthquake events. The artificial waves have identical phase angles to the recorded earthquake waves, and their overall response spectra are compatible with the seismic design spectrum with 5% of critical viscous damping. It is concluded that the artificial earthquake waves simulated in this paper are applicable as input ground motions for a seismic response analysis of building structures.