• The Korean Journal of Ecology
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• 제20권1호
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• pp.1-8
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• 1997

This study was conducted to investigate the distributions of the native and introduced dandelins in the western Kyonggido area and to determine the environmental factor influencing distribution of dandelions. One hundered and thirty seven study sites were randomly selected along roadsides in urban areas, arable lands, apartment areas and industry regions, and vegetation, dandelion's seed characters and soil acidity were sureyed. Throughout the areas the introduced dandelions were more widely distributed than the native ones. The native dandelions were scarcely distributed in the developed areas and roadsides. The introduced dandelions were dominantly distributed in the new environments where soils were alkalized by the trban development, road pavement, and construction of new buildings, while the native ones were mostly distributed in the rural area with weakly acid soil. The seed production of the introduced ones were two times more than that of the native ones. The seed of the introduced ones were lighter than that of the native ones. The introduced ones yield seeds more than four times a year. These results suggested the urbanization and the seed characters to bet the two dominant factors influencing the distribution of dandelions.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.42-51
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• 2003

The global demand for underground facilities has increased substantially in the past decades, and a substantial number of underground projects have had to deal with challenging ground conditions in urban environments. Particularly challenging are weak and unstable water bearing soils. Advancements in shielded TBM tech-nology have led to significant improvements regarding the ability to control ground deformations in soft ground. Nonetheless, ground collapse may occur even when the most advanced TBM designs are employed if unexpected adverse ground conditions are encountered or if insufficient stabilizing pressure is transferred to the tunnel face. This paper reviews common approaches for face stability and face pressure transmission calculations, and provides an overview of some of the latest technological developments and considerations for soft ground TBM applica-tions.

• Land and Housing Review
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• 제2권1호
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• pp.79-85
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• 2011

The bearing capacity of a soil can be improved by conventional ground improvement techniques such as stabilization and compaction methods. Recently, the use of geotextiles in improving the bearing capacity of soils has become popular because of the availability of durable and strong geosynthetic materials. In this paper, through the laboratory model tests on sandy ground reinforced by geotextiles with the strip footing under plane strain condition, the effects of bearing capacity improvement on the sandy ground and its behaviour were investigated.

• Earthquakes and Structures
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• 제2권4호
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• pp.377-396
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• 2011

In seismic design and structural assessment using the displacement-based approach, real structures are simplified into equivalent single-degree-of-freedom systems with equivalent properties, namely period and damping. In this work, equations for the optimal pair of equivalent properties are derived using statistical procedures on equivalent linearization and defined in terms of the ductility ratio and initial period of vibration. The modified Clough hysteretic model and 30 artificial accelerograms, compatible with the acceleration spectra for firm and soft soils, defined by the Japanese Design Specifications for Highway Bridges are used in the analysis. The results obtained with the proposed equations are verified and their limitations are discussed.

• Journal of Forest and Environmental Science
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• 제40권2호
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• pp.141-150
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• 2024

This study aims to develop and commercialize a soundproof wall capable of planting at the urban ecological. The vegetative soundproof wall developed in the study showed highly superb structural test results for sound absorption coefficients and met the quality standards in the sound-absorbing performance test. Its structure is systemized to supply water to soils and plant roots inside the planting basis with rainwater running down the inclined planes near the planting basis in the front of the vegetation panel. It allows for sporadic water supply for about 30 days of drought. The test results show that the plants continued favorable growth and development in leaves, stems, and roots, making the vegetative soundproof plate a product capable of reacting to climate environment changes.

• Journal of the Korean Geosynthetics Society
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• 제16권2호
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• pp.11-21
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• 2017

Ground subsidence mainly occurs due to the soil wash-away caused by cracked sewer pipes. It is necessary to understand the behavior surrounding soils with the formation of cavity and relaxation zone to set up counterplan. In this paper, a series of laboratory model tests and numerical analyses (Discrete Element Method) were performed to investigate the ground subsidence mechanism due to sewer pipe damage. For model tests, aluminum rod and trap door were used to simulate the behavior of model ground. Test results were compared with the numerical analyses conducted under the same boundary conditions with model tests. From this study, it was investigated the shape and size of cavity and relaxation zone due to the soil wash-away and a void ratio distribution of surrounding soils with relaxation properties.

• Journal of the Korean Geosynthetics Society
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• 제18권4호
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• pp.63-73
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• 2019

In this study, it was studied recycled soils with bentonite-polymer mixture in order to design economic landfill instead of clay liner. Recycled soil was used as SP, a sandy soil with 90.58% sand and 1.88% silt and clay. The recycled soils were mixed with 4%, 6%, and 8% bentonite by weight, and then compared with samples mixed with 2%, 3%, and 4% bentonite by weight in marine clay. Recycled soil satisfied the permeability criteria at 8%, and clay soil satisfied at 3%. In order to make a sample that satisfies the standard of the waste landfill, a permeability test was conducted by mixing 0.16%, 0.24%, and 0.28% of the polymer in a sample having 4% bentonite mixing ratio. The unconfined compression strength test was carried out at the same mixing ratio to confirm that the specification was satisfied. As the bentonite mixture ratio increased, the permeability coefficient and unconfined compression strength decreased. The strength in polymer mixing increased initially and then maintained a constant value. At 4% bentonite mixing ratio and 0.28% polymer mixing ratio, the coefficient of permeability was 1.0×10^-7 cm/sec or less, and the unconfined compression strength was over 500 kPa. It was confirmed that it can be used as a mixed liner material of waste landfills.

• Journal of Korean Society of Forest Science
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• 제78권1호
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• pp.11-25
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• 1989

Four regions have been selected and surveyed to investigate the effects of air pollution and acid deposition on forest ecosystem. They were Seoul as urban region, Yeochon and Ulsan as industrialized region, and Kangwondo as uncontaminated region. Soil pH and the distribution of elements were analyzed in process of time for three years as well as by distance from pollution sources. In general, forest soils acidified in process of time from pollution sources to suburban areas. Hydrogen ion concentration in forest soils increased in 1988 as much as 60% of that in previous year. Average soil pH values in coniferous forest were 4.45 in Seoul, 4.54 in Yeochon, 4.81 in Ulsan, and 6.03 in Kangwondo. Forest soil pH increased with the distance from pollution sources to suburban areas at constant rate within short ranges (up to 30 km) and at decreasing rate within long ranges (up to 200 km). On the contrary, sulfur content in soils decreased every year except in Yeochon region. Base saturation of forest soils in polluted regions were all below 20% level compared with 70% in Kangwondo region. Active aluminum content in soils increased with the soil acidification at the highest rate in Yeochon, and the next in Ulsan and Seoul. Heavy metal content such as copper and zinc in tree tissues were the lowest in Kangwondo region, and the next in Yeochon, Seoul and Ulsan.

• Economic and Environmental Geology
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• 제38권2호
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• pp.101-111
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• 2005

The objectives of this study we to assess the extent and degree of environmental contamination and to draw general conclusions on the fate of toxic elements derived from mining activities in Korea. 인t abandoned mines with four base-metal mines and four Au-Ag mines were selected and the results of environmental surveys in those areas were discussed. In the base-metal mining areas, the Sambo Pb-Zn-barite, the Shinyemi Pb-Zn-Fe, the Geodo Cu-Fe and the Shiheung Cu-Pb-Zn mine, significant levels of Cd, Cu, Pb and Zn were found in mine dump soils developed over mine waste materials, tailings and slag. Furthermore, agricultural soils, stream sediments and stream water near the mines were severely contaminated by the metals mainly due to the continuing dispersion downstream and downslope from the sites, which was controlled by the feature of geography, prevailing wind directions and the distance from the mine. In e Au-Ag mining areas, the Kubong, the Samkwang, the Keumwang and the Kilkok mines, elevated levels of As, Cd, Cu, Pb and Zn were found in tailings and mine dump soils. These levels may have caused increased concentrations of those elements in stream sediments and waters due to direct dis-charge downstream from tailings and mine dumps. In the Au-Ag mines, As would be the most characteristic contaminant in the nearby environment. Arsenic and heavy metals were found to be mainly associated with sulfide gangue minerals, and mobility of these metals would be enhanced by the effect of oxidation. According to sequential extraction of metals in soils, most heavy metals were identified as non-residual chemical forms, and those are very susceptible to the change of ambient conditions of a nearby environment. As application of pollution index (PI), giving data on multi-element contamination in soils, over 1.0 value of the PI was found in soils sampled at and around the mining areas.

• Journal of Soil and Groundwater Environment
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• 제24권6호
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• pp.9-15
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• 2019

Soil dust emitted from large scale construction sites in urban areas has posed a significant health threats to local residents by exacerbating air quality. Water-spraying (moistening) is commonly practiced to lower the dust emission in construction sites, but its long term effectiveness is highly questionable. In this study, the utility of starch and PVA(polyvinyl alcohol) was investigated in suppression of the soil dust emissions in construction sites in Seoul areas. The efficiency of the two suppressants was tested with test soil sample in a lab-scale wind tunnel box under different concentrations of suppressants and soil textures. Starch and PVA showed the superior ability to suppress soil dust emission as compared to moistening, resulting in PM₁₀ and PM_2.5 lower than the daily limit values of 30 and 15 ㎍/㎥ respectively. PVA showed higher suppression capability than starch for all conditions. The test soils mixed with suppressants also showed dramatically enhanced aggregate stability compared to the non-treated soil.