• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1396-1399
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• 2005

Gas permeability of the solidified sewage sludge needs to be characterized in order to use as a large-scale landfill cover material. Four different types of the samples were prepared for gas permeability experiments: (1) granite soil, (2) dried sewage sludge, (3) solidified sewage mixed with slag and (4) solidified sewage mixed with granite soils. The experimental instrumentation and measurement devices were newly designed and created to effectively evaluate gas permeability of the samples.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.768-774
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• 2008

To evaluate the effect of the solidified/stabilized sewage sludge on landfill sites, lysimeter tests were conducted. Lysimeters (LR1, LR2, and LR3) were filled with the material(Compost : Fodder : Sand = 10 : 10 : 80) and covered with different types of the cover soils, the G solidified sludge produced from the neutral solidifying chemical agent(LR1), the A solidified sludge produced from the alkali solidifying chemical agent(LR2), and the weathered granite soil(LR3). Those lysimeters were kept at the temperature controlled room with 30 $\pm$ 2$^{\circ}C$ for about 450 days. As the results, it was appeared LR2 > LR1 > LR3 that total gas production rate(L), gas production rate(L/VS(kg)) and cumulative gas(CO$_2$ + CH$_4$) production. There were not significant differences at decrease of the COD$_{Cr}$ in the leachate from LR1 and LR3. Thus, it had been shown that the use of the G solidified sludge as cover soil did not affect the COD$_{Cr}$ in the leachate. The COD$_{Cr}$ from LR2 had been increased since around 250 days because solidified/stabilized sewage sludge became re-slurry. T-N and T-P from LR3 also were higher than LR1 and LR2. Also were, the use of the solidified/stabilized sewage sludge as a cover soil, therefore, did not affect the T-N and T-Pconcentrations in the leachate.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.99-107
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• 2013

This study was conducted to evaluate the effect of soil covering depth and vegetation base materials on the competition between Pinus densiflora Siebold & Zucc. and Lespedeza cyrtobotrya Miq., which were grown in an abandoned coal mine land for three years after seeding, by comparing their growth and stem density. The study site was consisted of sub-plots with four different soil covering depths (0cm, 10cm, 20cm, and 30cm) and four different compounds of vegetation base materials (peat moss (control), soil conditioner+peat moss (S+P), erosion control material+peat moss (E+P), and soil conditioner+erosion control material+peat moss (S+E+P)). Results of this study showed opposite pattern between P. densiflora and L. cyrtobotrya with different soil covering depth and compounds of vegetation base materials in general. P. densiflora showed the highest growth and stem density in plots with 10cm and 0cm depths of soil covering, respectively, while the lowest was shown in plots with 20cm depth of soil covering. In contrast, L. cyrtobotrya showed the highest growth and stem density in plots with 20cm depth of soil covering, while the lowest was shown in plots with 0cm depth of soil covering. In case of vegetation base materials, P. densiflora showed the highest growth and stem density in control plots and plots treated with S+P, respectively, while the lowest was shown in plots with S+E+P treatment. On the other hand, L. cyrtobotrya showed the highest growth and stem density in plots treated with S+E+P, while the lowest was shown in control plots. These results suggested the competition between two plants as a major cause of opposite patterns, which is induced by the suppressed growth and stem density of P. densiflora by fast growing L. cyrtobotrya. Despite the suppression of L. cyrtobotrya on P. densiflora, L. cyrtobotrya can play a positive role in improving soil quality, and thus it would be more desirable for restoring abandoned coal mine land to manage the growth of L. cyrtobotrya periodically, rather than eliminate them.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.256-272
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• 2002

The purpose of this study is to develop landslide susceptibility analysis techniques using artificial neural network and to apply the newly developed techniques to the study area of Boun in Korea. Landslide locations were identified in the study area from interpretation of aerial photographs, field survey data, and a spatial database of the topography, soil type, timber cover, geology and land use. The landslide-related factors (slope, aspect, curvature, topographic type, soil texture, soil material, soil drainage, soil effective thickness, timber type, timber age, and timber diameter, timber density, geology and land use) were extracted from the spatial database. Using those factors, landslide susceptibility was analyzed by artificial neural network methods. For this, the weights of each factor were determinated in 3 cases by the backpropagation method, which is a type of artificial neural network method. Then the landslide susceptibility indexes were calculated and the susceptibility maps were made with a GIS program. The results of the landslide susceptibility maps were verified and compared using landslide location data. A GIS was used to efficiently analyze the vast amount of data, and an artificial neural network was turned out be an effective tool to maintain precision and accuracy.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.08a
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• pp.75-87
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• 2005

Remote sensing(RS)- and geographic information system(GIS)-based information management to measure and assess agri-environment schemes, and to quantify and map environment indicators for nature and land use, climate change, air, water and energy balance, waste and material flow is in high demand because it is very helpful in assisting decision making activities of farmers, government, researchers, and consumers. The versatility and ability of RS and GIS containing huge soil database to assess agricultural environment spatially and temporally at various spatial scales were investigated. Spectral and microwave observations were carried out to characterize crop variables and soil properties. Multiple sources RS data from ground sensors, airborne sensors, and also satellite sensors were collected and analyzed to extract features and land cover/use for soils, crops, and vegetation for support precision agriculture, soil/land suitability, soil property estimation, crop growth estimation, runoff potential estimation, irrigated and the estimation of flooded areas in paddy rice fields. RS and GIS play essential roles in a management and monitoring information system. Biosphere-atmosphere interection should also be further studied to improve synergistic modeling for environment and sustainability in agri-environment schemes.

• Clean Technology
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• v.8 no.2
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• pp.67-76
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• 2002

Dewatered sludge of 400,000t/y from water treatment plants in Korea is being disposed through landfill and ocean dumping. However, the disposal is posing more and more serious environmental problems at the same time not only because of landfill site shortage in municipal suburbs, but because of the concern it will contaminate the oceans. In this study, the research on utilizing the sludge dried by flash dryer as covering soil in the landfill sites was carried out to solve these problems on environmental affinity. Both dewatered and dried sludge were exposed to the natural condition and observed according to the atmospheric changes. An experiment of soil engineering characteristics of the dried sludge and tests on mixed sludge(silty sandy soil : dried sludge = 10:90 ~ 30:70) such as particle size distribution, liquid and plastic limit, moisture content, specific gravity and compaction test were carried out. According to the compaction test, the compaction was confirmed as the optimum water content ratio was observed in the condition of SM-silty sand of particle size distribution, NP of liquid and plastic limit, 101.4% of moisture content, 2.04~2.12 of specific gravity. The results showed that dried sludges mixed with at least 30% of natural soil could be used as daily covering soil in the landfill sites.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.25-40
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• 2007

Excessive earth pressure is one of the major mechanical factors in the deformation and damage of Cut-and-Cover Tunnel lining in shallow tunnels and portals of mountain tunnels (Kim, 2000). Excessive earth pressure may be attributed to insufficient compaction and consolidation of backfill material due to self-weight, precipitation and vibration caused by traffic (Komiya et al., 2000; Taylor et al., 1984; Yoo, 1997). Even though there were a lot of tests performed to determine the earth pressure acting on the tunnel lining, unfortunately there were almost no case histories of studies performed to determine remedial measures that reduce differential settlement and excessive earth pressure. In this study the installation of geotextile mat was selected to reduce the differential settlement and excessive earth pressure acting on the cut-and-cover tunnel lining. In order to determine settlement and earth pressure reduction effect (reinforcement effect) of geotextile mat reinforcement, laboratory tunnel model tests were performed. This study was limited to the modeling of rigid circular cut-and-cover tunnel constructed at a depth of $1.0D\sim1.5D$ in loose sandy ground and subjected to a vibration frequency of 100 Hz. Model tests with varying soil cover, mat reinforcement scheme and slope roughness were performed to determine the most effective mat reinforcement scheme. Slope roughness was adjusted by attaching sandpaper #100, #400 and acetate on the cut slope surface. Mat reinforcement effect of each mat reinforcement scheme were presented by the comparison of earth pressure obtained from the unreinforced and mat reinforced model tests. Soil settlement reduction was analyzed and presented using the Picture Analysis Method (Park, 2003).

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1316-1323
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• 2005

Most tunnel lining material which has been used in the domestic is a concrete. But many problems as the construction period, the cost, and the crack occurrence for the design, construction, and management were happened in the concrete lining. For this reason, many research institutes like the Korea Highway Corporation recognize the necessity of an alternate material development and grow on the interest for that. So in this study, the behaviour characteristics for the application of the Corrugated Steel Plate Lining in cut-and-cover tunnel are evaluated as several conditions for the backfill height, the cutting slope, and the relative density of backfill soil are changed. In addition, through using that conditions, CHBDC(2000, Canadian Highway Bridge Design Code) is evaluated if it could be applied to the design by comparing with the numerical analysis results. As the behaviour characteristics of the Corrugated Steel Plate Lining by CHBDC and the static numerical analysis are analyzed, both the methods show the same linear increases of the compressive stress according to the increase of the backfill height. The CHBDC of the dead load condition has very similar tendency by comparing with the result of the static numerical analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1295-1302
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• 2006

Controlled low-strength material(CLSM) which is easily excavated and also known as flowable material, is commonly used as a backfill in utility trenches and other applications. In this study, a rapid-setting flowable material a kind of CLSM made with a field soil were evaluated by an experimental study. The properties ordinarily desired from the mix are: (a) flow under gravity; (b) hardening for early workability(after 4 hours)and cover; and (c) ultimate strength low enough to allow ready excavation. Fluidity of fresh material is evaluated using a simple spread test. Hardening is measured by a mortar penetrometer, and these values are correlated with unconfined compressive strength. It is desirable to keep the ultimate strength to less than $5.6kg/cm^2$ somewhat less target strength is selected for the 28-day value.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.27-40
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• 2006

Damage of cut-and-cover tunnel lining can be attributed to physical and mechanical factors. Physical factors include material property, reinforcement corrosion, etc. while mechanical factors include underground water pressure, vehicle loads, etc. This study is limited to the modeling of rigid circular cut and cover tunnel constructed at a depth of $1.0{\sim}1.5D$ in loose sandy ground and subjected to a vibration frequency of 100 Hz. In this study, only damages due to mechanical factors in the form of additional loads were considered. Among the different types of additional, excessive earth pressure acting on the cut-and-cover tunnel lining is considered as one of the major factors that induce deformation and damage of tunnels after the construction is completed. Excessive earth pressure may be attributed to insufficient compaction, consolidation due to self-weight of backfill soil, precipitation and vibration caused by traffic. Laboratory tunnel model tests were performed in order to determine the earth pressure acting on the tunnel lining and to investigate the applicability of existing earth pressure formulas. Based on the difference in the monitored and computed earth pressure, a factor of safety was recommended. Soil deformation mechanism around the tunnel was also presented using the picture analysis method.