• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.206-215
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• 1998

Using of geosynthetics with linear materials(sand, gravel, clay soil) is rapidly increased in landfill. With geosynthetics, geotextiles often expose to solar radiation(Ultraviolet) on long terms during the installation. In this paper, the results will represent the strength retention rate and tensile retention rate of geotextiles between outdoor exposed and protected by 15cm thickness of soil. As a result of cumulating solar radiation in geotextiles was increased, the strength retentions rate of P.P(500g/$m^2$), P.P(700g/$m^2$) and P.P(1000g/$m^2$) were decreased and the lower weight of unit area of geotextiles, the faster decrease of strength retention rate. P.E.T(600g/$m^2$) was showed a distinctive trend that the strength retention rate increased. The tensile retention rate of tested geotextiles was decreased during the simulation. However, the strength and tensile retention rate of geotextiles covered by soil had changed insignificantly. Therefore, it can surmise that the soil covering will help geotextiles to be protected from UV effecting

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1315-1323
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• 2010

This paper deals with a case study on a unique slope failure in a liner system of a municipal solid waste containment facility during construction because the sliding interface is not the geomembrane/compacted low permeability soil liner (LPSL) but a soil/soil interface within the LPSL. From the case study, it is concluded that compaction of the LPSL should ensure that each lift is kneaded into the lower lift so a weak interface is not created in the LPSL, and the LPSL moisture content should be controlled so it does not exceed the specified value, .e.g., 3% - 4% wet of optimum, because it can lead to a weak interface in the LPSL. In addition, drainage materials should be placed over the geomembrane from the slope toe to the top to reduce the shear stresses applied to the weakest interface, and equipment should not move laterally across the slope if it is unsupported but along the slope while placing the cover soil from bottom to top.

• Geotechnical Engineering
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• v.7 no.1
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• pp.7-14
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• 1991

Determination of dynamic shear modulus of soil was made by measuring directly the velocity of ultrasonic shear waves transmitted through the specimen. The PUNDIT, a generator and detector of ultrasonic waves, has been used to measure the propagation velocity. Forty -six tests of compacted soil at seven different void ratios and seven varying degrees of saturation with four types of materials were made in this study. The primary importance in this study was the investigation of the relations among the para meters which influenced G-modulus, As a results of analysis, the dynamic shear modulus of soil tends to decrease with an increase of void ratio, and also it is affected by soil types. In case of using PUNDIT, the proper range of the specimen length is from 5cm to 8cm. And the degree of saturation doesn't affect the dyn- amic shear modulus of soil.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.229-236
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• 2003

Ultrasonic propagation velocities of both the dilatational and shear waves through the weathered tuff soil sampled from the area tying between Ulanbator and Beijing were measured under temperature condition of near subzero by means of sing-around method. After comparing the results with obtained data on unfrozen water content, a linear relation between velocities and unfrozen water content was performed with high coefficient value. Experimental results of two kinds of rather uniform materials, namely, glass-beads and silica micro-beads, testified the similar linear relations. In addition, the change rate of dilatational wave velocities with the change of volumetric unfrozen water content was not dependent on soil type. Although a rational theory of the ultrasonic velocities dependence on the unfrozen water content is not yet proposed, the presented empirical relationships may suggest the appropriate evaluation to the effect of unfrozen water on dynamic characteristics of frozen soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.580-585
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• 2004

The purpose of this study is the stability evaluation of soil slope according to inclination of upper natural slope. Upper natural slope breeds loss of slope by inflow in slope of surface water by rainfal1 and f1uctuation of amount of materials in slope through method of cutting slope according to degree of inclination. Basis of standard inclination does not consider of inclination of upper natural slope and is presented uniformly. Therefore, in this study, analyzed stability of inclination of upper natural slope through limit equilibrium analysis. Result is same as following. First, safety factor through limit equilibrium analysis is almost direct decrease when gradient of soil slope is 1:1.2, 1:1.5. However, when gradient of soil slope is 1:1.0, 1:0.7, if sinclination of upper natural slope are $20^{\circ}$, it shows tendency that decrease of safety factor becomes low rapidly. Second, when when gradient of soil slope is fixed, inclination of upper natural slope increase tendency(maximum 3.0 times) that decrease of safety factor.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.123-135
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• 1997

In order to investigate the dispersion patterns and contamination level of heavy metals in the soil-ecosystem and to evaluate the efficiency of soil remediation by reversed soil method, soils and plants were collected from the Dongjin Au-Ag-Cu mine area and analysed for heavy metals. The dispersion patterns of heavy metals in soils and plants show that heavy metal pollutions caused by waste rump around Dongjin mine are mainly found in the vicinity of the waste rump and in the southward slanting of mine. Toxic metallic pollutants from the mine influence heavy metal contents in paddy soils in downstream area, and may be a potential sources of heavy metal pollution on crop plants. Soil samples collected from the remediated rice farming field by reversed method show similar levels of heavy metal content to those from the polluted rice farming field, but topsoil enrichment of heavy metals are not found. Heavy metal contents of the rice plants collected from remediated rice farming field are significantly lower than those from polluted rice farming field, and it suggests that the reversed soil method is effective for the reduction of bioavailability of heavy metals.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.1-8
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• 2018

BACKGROUND: Different physical and chemical properties of biochar, which is made out of a variety of biomass materials, can impact water movement through amended soil. The objective of this research was to develop a decision support tool evaluating the impact of the shape and the size distribution of biochar on soil saturated hydraulic conductivity ($K_{sat}$). METHODS AND RESULTS: Plastic beads of different size and morphology were compared with biochar to assess impacts on soil $K_{sat}$. Bead and biochar were added at the rate of 5% (v/w) to coarse sand. The particle size of bead and biochar had an effect on the $K_{sat}$, with larger and smaller particle sizes than the original sand grain (0.5 mm) decreasing the $K_{sat}$ value. The equivalent size bead or biochar to the sand grains had no impact on $K_{sat}$. The amendment shape also influenced soil hydraulic properties, but only when the particle size was between 3-6 mm. Intra-particle porosity had no significant influence on the $K_{sat}$ due to its small pore size and increased tortuosity compared to the inter-particle spaces (macro-porosity). CONCLUSION: The results supported the conclusion that both particle size and shape of the amended biochar impacted the $K_{sat}$ value.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.1
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• pp.153-163
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• 2015

The study was conducted to develop ecological restoration method of damaged area in DMZ vicinities. As the material for the ecological restoration, forest soil and trees waste have been used. Forest soils were collected for experiments in Yanggu, Gangwon Province. Effect of ecological restoration was analyzed through germination experiment. Germination experiment was performed using 12 kinds of woody and herbaceous seeds. Woody and herbaceous seed germination in test pot was relatively evenly. Mixed material consisting of forest soil and trees waste seemed a possibility as the material for the restoration. The effects on seed germination were higher in the case of mixing more than 70% by volume ratio of local resources. Total number germinated individuals were different depending on the mixing ratio of soil sampling depth. Individual plants showed different trends depending on the experimental combination. Results of the woody seed germination were affected only in the soil sampling depth. Seed germination of herbaceous received a combined effect on soil sampling depth and mixing ratio.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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• pp.261-269
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• 2014

Most areas in Gangwon-do are mountainous regions where causes heavy damages due to landslides. It is important to analyze basic factors influencing the cause of landslides in order to prevent such landslides. For this study, a landslide occurring site is extracted from aerial images taken after the landslide caused by typhoon 'Ewiniar' in Pyeongchang area 2006. Also, the overlay analysis with the topographic, forest, and soil maps in this area is performed using GIS based methods. In addition, the topographic, forest, and soil characteristics relating to the landslide factors are analyzed. As a result, large numbers of landslides occurred at a slope angle of $20^{\circ}-40^{\circ}$. In the case of the forest factors, there are close relationships between the artificial pine and larch forests and the frequency of landslides. The low forest density represents a weakness in landslides. In the case of the soil factors, a higher level in the surface soil with a type of sandy loam soil, a higher gravel content in subsoil, and a higher degree of acid rocks in soil parent materials cause higher frequencies in landslides.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.169-176
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• 2011

The purpose of this study is to examine the ecologically suitable restoration characteristics in riparian slopes constructed by continuous fiber soil reinforced system (Geofiber system) which does not contain the concrete materials. The findings are as follows : (1) as the tested soil was not washed away by rainfalls and floods, Geofiber could replace the concrete wall and gravity stone net bag technique from the civil engineering structural point of view; (2) after one year of the construction, it was monitored that land cover ratio was 80-90%, which indirectly shows that vegetation is safely maintained; and (3) at the same time, 5-8 flora species were found in each test grid and more importantly dominant species have been moved from alien species to native herbaceous plants. From the above findings, Geofiber system is recommendable to restore the riparian slopes in terms of stability and natural landscape points. However, a long term monitering is needed considering flora succession process in a given environment as well as suitability tests should be carried out through the comparative investigations in other environments.