• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.1-9
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• 2020

This study analyzes contaminant movement under transient flow in a rubble mound revetment offshore waste landfill barrier system that prevents contaminant runoff. The barrier system consists of bottom layer and side barrier. For the bottom layer system, impermeable clay layer is used. For the side barrier system, the HDPE barrier sheet (primary element) plays the main role, and the intermediate protection layer (supplementary element) is responsible for the barrier. Seepage, advection, dispersion numerical analysis was carried out using SEEP / W and CTRAN / W programs. As a result, under abnormal conditions considering the fluctuation in tidal range, the volume and direction of the flow velocity vector of the pore water change with time and the dispersion concentration of the contaminant changes. When comparing the case of 2 m tidal range and 8 m tidal range, the larger the tide value, the higher the concentration of contaminant under abnormal conditions. It was found that the rate of change of the concentration of the contaminant changed depending on the change in the tidal range, and as a result, the outflow of the pollutant was smaller than that in the steady flow state.

• Journal of Conservation Science
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• v.37 no.6
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• pp.748-766
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• 2021

The Iksan Ssangneung (twin tombs), a pair of tombs comprising the Daewangneung (large royal tomb) and the Sowangneung (small royal tomb), were constructed in the typical style of stone tunnel and chamber tombs in the Baekje Kingdom during the Sabi period (538 to 660 AD) of ancient Korea. Soil layers exposed during excavation of Sowangneung in a trench east of the tomb are: the bottommost layer, the ground level layer, the Panchuk (rammed earth) layer of the Baekje, the layer created by a grave robbery, and soil recovered during the Japanese colonial period. Soil samples were obtained by segmenting an easy stratigraphic horizon into sub categorized soil layers, and their material properties were analyzed; they are composed mainly of sandy loam based on the particle size distributions. In the site foundation, loamy sand is packed in the bottommost layer, and sandy loam with high sand and silty sand fills most of the overlying layer. The central and topmost portion of the Baekje layer is composed of loam with high clay content. All soil layers show geochemical behaviors similar to those of the bottommost layer. X-ray diffraction analysis verified kaolinite in all layers, also observed in soil layers displaying high crystallinity. Kaolinite and halloysite were identified by scanning electron microscopy. Thus, we conclude that the Baekje layer of the Sowangneung is composed of sandy loam containing kaolin procured from near the site. An impermeable middle to upper layer was created using viscous loam. The top of the tomb was closed tightly.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.179-189
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• 2000

The purpose of this research is to complement the existing researches on landfill bottom liners behavior during the periods of freeze and thaw. Landfill-related researches have been typically focused on small-scale soil samples that are often compacted under conditions different from those used in the field. Although these tests have been invaluable in clarifying the problem of freeze and thaw, extending the results of such experimental studies to prototype landfills are questionable. In this investigation, the author utilized a large scale laboratory simulation allowing inclusion of the field depth of the cover systems, layered soil profiles, rainfall simulation, a cold climate and boundary conditions similar to those encountered in the landfill. The soil materials were stabilized soils (mixed clays, cements, and minerals) instead of clays. The bottom liners are made up of drainage layer (30 cm), stabilized layer (75 cm), and leach collection layer (60 cm). The stabilized layers are made up of supporting layer (45 cm) and low permeable layer (30 cm) - consisting of $P_A\; and\; P_B$ layer. As a results, depths of penetration increased by about 2~5 more centimeters at rainfall simulated designs than those at no rainfall simulated designs (that is design 3, design 5 and design 7) - it increased by about 20mm/day in the bottom liners and frost heaves also increased it by a few millimeters. Also, a few cracks appeared partly. According to these results, we can surmise that the compacted stabilized soil is more reliable than the compacted clay liners for construction of the landfill liners.

• Journal of the Korean Geographical Society
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• v.41 no.2 s.113
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• pp.150-167
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• 2006

This study was conducted to determine the pedogenesis of dense subsurface horizons (denoted either Bx or Bd) observed within closed depressions and in toeslope positions at loess-covered glacial tillplains in southern Wisconsin. Some of these dense subsurface horizons, especially those occurring within depressions, show a close morphological resemblance to fragipans elsewhere, even though the existence of fragipans has not been previously reported in southern Wisconsin. The spatial occurrence of fragipans was first examined over the landscape to characterize general soil-landscape relationships. Detailed physico-chemical and micromorphological analyses were followed to investigate the development of fragipans within a closed depression along a catenary sequence. The formation of fragipans at the study site is a result of sequential processes of physical ripening and accumulation of colloidal materials. A very coarse prismatic structure with a closely packed soil matrix was formed via physical ripening processes of loess deposited in small glacial lakes and floodplains that existed soon after the retreat of the last glacier. The physically formed dense horizons became hardened by the accumulation of colloidal materials, notably amorphous Si. The accumulation intensity of amorphous Si varies with mass balance relationships, which are governed by topography and local drainage conditions. Well-developed Bx horizons evolve at closed depressions where net accumulation of amorphous Si occurs, but the collapsed layers remain as Bd horizons at other locations where soluble Si has continuously been removed downslope or downvalley. Hydromorphic processes caused by the presence of fragipans are degrading upper parts of the prisms, resulting in the formation of an eluvial fragic horizon (Ex).

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.63-76
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• 2015

This study was carried out to suggest improvement plans for problems with the landscape areas of highway service areas. The survey factors were land use, placement of green area and land coverage in terms of spatial and environmental property. Noise and topographic structure in detached green areas were surveyed in terms of impact factor. The status of the planting area around each service area was analysed in regards to planting structure and planting landscape. As a result, the mean of rations of land use were 81.6% building and 18.4% green areas, which were composed of 5.4% landscape area, 9.1% buffer area, etc. Planting areas as usable space accounted for only 0.7%, and the result of noise measurement was different according to the distribution of highway and service area and type of detached green area. The mean of ratio of planting area was 18.4%, which consists of 6.7% landscape planting, 3.4% other green area, 4.6% buffer area, 2.0% buffer and landscape area, 1.1% shade planting and 0.5% landscape and shade planting. Most planting areas aim at landscape appreciation and areas in which visitors can relax and gain recreation were insufficient. The planting structures of service areas were 52.2% canopy layer, 11.8% shrubs and 9.4% canopy and shrub layers, and most of the planting areas were a single layer of green area. Multi-layered planting structures in the landscape and buffer areas were required and a shade planting area was needed to improve amenities as planting canopy layered trees. This study suggested improvement methods for based environments, spatial function and planting function in landscape areas.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.125-135
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• 2005

Generation and transport of nonpoint source pollution, especially sediment-associated pollutants, are profoundly influenced by hydrologic features of runoff. In order to identify pollutant export rates, hence, clear knowledge of rainfall-runoff relationship is a pre-requisition. In this study, performance of AnnAGNPS model was assessed based on the ability of the model to predict rainfall-runoff relationship. Three catchments, each under different nearly single land use, were simulated. From the results, it was found that the model was likely to produce better predictions for larger catchments than smaller catchments. Because of using the daily time scale, the model could not account for short durations less than 24 hours, especially high intensity events with multiple peak flow that significantly contribute to the generation and transport of pollutants. Since CN information for regional areas has not been built up, a careful selection of CN is needed to achieve accurate prediction of runoff volume. Storm distribution also found to be considered as an important calibration parameter for the hydrologic simulation.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.296-304
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• 2015

The rapid increase in the number of climate disasters combined with the scale of change and the diversification of natural disasters require a radical solution. In particular, the urban space is more complex, therefore we need to establish measures for disaster response and how to react to damaged infrastructure based on the phenomenon of an increase in the urban population and the impermeable layer being extended. The social problems related to the economic burden of land purchase and the securing of a disaster prevention system can be solved simultaneously by introducing the park system for disaster reduction into the public land of the green space in the city. The local government has recently adapted diverse systems of disaster mitigation and carried out pioneer projects according to the guidelines for the construction of the urban park for disaster prevention published by the Ministry of Land, Infrastructure and Transport. The purpose of this study is to propose a composition model for neighborhood parks to prevent disaster through urban green spaces which has the functions of water management and biotope conservation. The result of this study will contribute to utilize the climate change adaptation model for living area neighborhood parks in the existing urban structure.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.3
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• pp.35-45
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• 1999

The research is to examine urban heat island effects which is resulted from urbanization using thermal infrared band of Landsat TM data and to demonstrate heat island alleviation effects of green spaces through correlation analysis of NDVI(Normalized Difference Vegetation Index) and surface temperature. According to the results, forests which are covered with natural vegetation have a high NDVI digital values, but surface temperature is very low, and urban areas which is composed of artificial paving materials have a low NDVI, surface temperature increases gradually. In summary, the analysis of relationship between NDVI and surface temperature, used in this study, is regarded as one of effective methodologies for proving heat island alleviation effects of vegetation.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.657-665
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• 2012

The development projects distort the natural water circulation system and increase the non-point source pollution by changing the natural cover type. The low impact development (LID) techniques are considering as new development approach to decrease the ecological- and hydrological impacts from high imperviousness rate. The high imperviousness rate is because of the construction of building, parking lot and road for human activities. Knowing the basic characteristics of rood runoff can give the direction for setting up the water management strategy. The monitoring results show the pollutant EMCs of roof runoff are 3~13 times lower than EMCs of the road and parking lot. The pollutant sources from roof runoff are mainly from leafs, cigarette butts, atmospheric deposition and materials of the roof. The EMC is occurred around 15minutes later after starting runoff and more than 8 storm events are needed to have the average EMCs.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.155-163
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• 2010

The flash flood is characterized as flood leading to damage by heavy rainfall occurred in steep slope and impervious area with short duration. Flash flood occurs when rainfall exceeds Flash Flood Guidance(FFG). So, the accurate estimation of FFG will be helpful in flash flood forecasting and warning system. Say, if we can reduce the uncertainty of rainfall-runoff relationship, FFG can be estimated more accurately. However, since the rainfall-runoff models have their own parameter characteristics, the uncertainty of FFG will depend upon the selection of rainfall-runoff model. This study used four rainfall-runoff models of HEC-HMS model, Storage Function model, SSARR model and TANK model for the estimation of models' uncertainties by using Monte Carlo simulation. Then, we derived the confidence limits of rainfall-runoff relationship by four models on 95%-confidence level.