• The Journal of Engineering Geology
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• v.26 no.4
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• pp.473-484
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• 2016

This study aims to establish a monitoring method for managing the effective maintenance of tailings dams. The monitoring of a tailings dump area involves several parameters and their investigation through a selection of evaluation items. The extents of defects and progressive failures also need to be effectively estimated. Therefore, the monitoring items can be subdivided into categories relating to the retaining wall structure (concrete wall, reinforcing stone wall, mesh gabions) and general facilities (liner, covering soil, slope, tailings, rain protection facility, leachate, planting), and quantitative evaluations can then be conducted for each condition. In doing so, we developed a systematic monitoring method that assesses the dam maintenance condition with grades and scores. The field application of the monitoring method results showed it to provide a more detailed evaluation than existing monitoring methods: the method detected an additional 16 defects missed by conventional methods. The evaluation gave scores of 89.3, 22.2, and 27.8 to the Geumjang mine tailings dam, the Gupoong mine tailings dam, and the Hwachun mine tailings dam, respectively. The advanced method can provide quantitative evaluation and perform detailed monitoring of the dams. This quantitative evaluation can be used to decide on maintenance priorities, select the main management items, and establish schedules of maintenance.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.311-316
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• 2015

This study defined and classified no-net-loss-of-greenness (NNLG) based on the law, and then assessed the NNLG index by metropolitan cities and provinces in Korea after estimating NNLG evaluation indicators for the introduction of NNLG for health improvement of urban ecosystems. The results are as follows. First, NNLG was the comprehensive meaning that was included in the greenbelt and park greenbelt and the green area which was defined by the Act on Urban Parks, Greenbelts, etc. and the National Land Planning and Utilization Act respectively. Second, NNLG was classified as a park greenbelt which was included urban parks and greenbelts such as buffer greenbelts, scenic greenbelts, and connecting greenbelts, green areas which was included in green conservation areas, green production areas, green natural areas, and green coverage which is included forests, grasslands, and wetlands that were occupied by vegetation such as trees, shrubs, and plants. Third, NNLG index by cities and provinces was assessed based on the estimation of NNLG evaluation indicators, which included parks and greenbelt areas per capita, green areas per capita, green coverage per capita, ratio of parks and greenbelts, ratio of green areas, and ratio of green coverage. As a result, Sejong city got the highest point of NNLG index and Seoul and Daegu got lowest points of NNLG index among metropolitan cities in Korea. Chungbuk got the highest point of NNLG index and Kyonggi and Jeju got lowest points of NNLG index among provinces in Korea.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.305-310
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• 2015

In 2014, the city of Seoul revised the ordinance regarding water-cycle restoration in the Seoul Metropolitan areas by incorporating the 'Low Impact Development (LID)' policy. The new ordinance plan will utilize 630 mm or almost 45 to 50% of annual rainfall until 2050 by means of providing a rainwater management system consisting of infiltration, retention and vegetation. The LID is believed to be the key to achieving the target requirements, specifically in development projects. This research was performed to evaluate the stormwater runoff and pollutant reduction performance of three different LID facilities (water circulation facilities) including an infiltration inlet, bioretention swale, and permeable pavement constructed in Seoul City. Results show that among the water circulation facilities, the permeable pavement achieved the highest runoff reduction as it was able to entirely capture and infiltrate the runoff to the ground. However, in order to attain a long-term performance it is necessary to manage the accumulated sediment and trapped pollutants in the landscape areas through other water circulation techniques such as through soil erosion control. In terms of pollutant reduction capability, the infiltration inlet performed well since it was applied in highly polluted areas. The bioretention facility integrating the physico-chemical and biological mechanisms of soil, microorganisms and plants were able to also achieve a high runoff and pollutant reduction. The water circulation facilities provided not only benefits for water circulation but also various other benefits such as pollutant reduction, ecological restoration, and aesthetic functions.

• Ecology and Resilient Infrastructure
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• v.4 no.3
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• pp.149-155
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• 2017

Willow plants are representative biomaterials used in river restoration and main target trees in stream managements. In order to understand the changes in the growth of Salix subfragilis and S. chaenomeloides with their stand ages, we investigated the density, height and basal area of stems and biomass at their different aged stands of the riparian zone of the sand-bed stream, the Nakdong River, Korea. We also developed allometric equations for estimating the biomass of these two species by establishing the relationship between diameter at breadth height and tree height with above-ground biomass. The stem density showed a sharp decrease for 3 years after germination for S. subfragilis and 6 years for S. chaenomeloides, resulting in strong self-thinning. The stem height of the two species increased to 7.5 m in 15 years for S. subfragilis, and to 14 m in 13 years for S. chaenomeloides. Aboveground biomass also increased rapidly at the early stage of growth. The biomass increased to 17 ton DM/ha in 13 years for S. subfragilis and to 1,110 ton DM / ha in 13 years for S. chaenomeloides. It is expected that the allometric equations of two Salix species derived from this study will be applied to the objectively estimating the biomass of willow plants for the management of floodplain trees in streams.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.75-84
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• 2013

Soil freezing is a phenomenon arising due to temperature difference between atmosphere and ground, and physical properties of soils vary upon the phase change of soil void from liquid to solid (ice). A heat-transfer mechanism for this case can be explained by the conduction in soil layers and the convection on ground surface. Accordingly, the evaluation of proper thermal properties of soils and the convective condition of ground surface is an important task for understanding freezing phenomenon. To describe convection on ground surface, simplified coefficient methods can be applied to deal with various conditions, such as atmospheric temperature, surface vegetation conditions, and soil constituents. In this study, two methods such as n-factor and convection coefficient for the convective ground surface boundary were applied within a commercial numerical program (TEMP/W) for modeling soil freezing phenomenon. Furthermore, the numerical results were compared to laboratory testing results. In the series of the comparison results, the convection coefficient is more appropriate than n-factor method to model the convective boundary condition.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.479-489
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• 2005

The floras of Jisimdo, Naedo and Yundoldo around Koje Island were investigated 3 times from January 2004 to November 2004. The vascular plants recorded were 165 taxa, 1 forms, 15 varieties, 149 species, 140 genera, 72 families, The rare and endangered plants were recorded as 1 taxa (Quercus gilva Blume), Korean endemic plants were recorded as 2 taxa (1 variety, 1 species, 2 genera, 2 families). The naturalized plants were 10 taxa, 10 species, 10 genera, 6 families, $3.52\%\;and\;6.1\%$ among the total naturalized plants and Urbanization Index in Korea. Anglers and visiter's number is expected to increase fast because nature of Jisimdo, Naedo and Yundoldo, in which kind and number of naturalized plants are forecasted to be increased more.

• Korean Journal of Plant Resources
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• v.33 no.4
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• pp.311-336
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• 2020

The flora of Sejong were summarized as 531 taxa including 104 families, 315 genera, 462 species, 3 subspecies, 59 varieties and 7 form. The rare plants were 8 taxa including Nepeta cataria L. and Aristolochia ontorta Bunge. The Korea endemic plants were 9 taxa including Populus tomentiglandulosa T. B. Le and Clematis trichotoma Nakai.. The specific plants were 42 taxa including Phytolacca esculenta Van Houtte(V), Corydalis decumbens (Thunb.) Pers(IV), Poncirus trifoliata Raf(III), Pseudostellaria coreana (Nakai) Ohwi(II), Cyrtomium fortunei J.Sm.(I). The naturalized plants were 49 taxa including Sicyos angulatus L, Ambrosia trifida L, Physalis angulata L. Panicum dichotomiflorum Michx., Galinsoga parviflora Cav, and Erigeron philadelphicus L. Especially, Sicyos angulatus L., Phytolacca americana L. and Bidens frondosa L. have been spread throughout the country are required to manage. The naturalized index(NI) and urbanized index(UI) were 8.7% and 15.3%. Useful plants incuding Edible was 199 taxa, Pasture was 193 taxa, Medicinal was 178 taxa, Ornamental was 82 taxa, Timber was 25 taxa, Fiber was 18 taxa, Stain was 9 taxa. Useful plants will be important materials for plant design in recreational and healing forests.

• Explosives and Blasting
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• v.21 no.3
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• pp.23-35
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• 2003

An analytical diffusion model for flood routing with backwater effects and lateral flows is developed. The basic diffusion equation is linearized about an average depth of (H + h), and is solved using the boundary conditons which take into account the effects of backwater and lateral flows. Scouring phenomenon around pier which affects on the support function of pier and the stabilization if river bed is a complex problem depending on flow properties and river bed state as well as pier geometry. therefore, there is no uniting theory at present which would enable the designer to estimate, with confidence, the depth of scour at bridge piers. The various methods used in erosion control are collectively called upstream engineering, HEC-RAS Model, underwater blasting. They consist of reforestation, check-dam construction, planting of burned-over areas, contour plowing and regulation of crop and grazing practices. Also included are measures for proper treatment of high embankments and cuts and stabilization of streambanks by planting or by revetment construction. One phase of reforestation that may be applied near a reservoir is planting of vegetation screens. Such screens, planted on the flats adjacent to the normal stream channel at the head of a reservoir, reduce the velocity of silt-laden storm inflows that inundate these areas. This stilling action causes extensive deposition to occur before the silt reaches the main cavity of the reservoir.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1013-1020
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• 2008

To evaluate the pollutant removal efficiency and clarify the cause of low removal efficiency of the wetland, temporal and spacial distributions of water quality were investigated at 16 sites in the Sihwa constructed wetland. The removal efficiency showed a tendency to decrease since the construction of the wetland, except for TN. In addition, the efficiency was largely varied with season, especially BOD and TP. No removal efficiency of BOD was observed in April and July when algal bloom was occurred in lower part open water of the wetland. On the other hand, TP showed no removal efficiency from April to August showing -291% of removal efficiency in August. From the horizontal distribution in closed water regions, SS concentration for the central area was significantly higher than for left and right areas(p = 0.013, center > left > right areas). From the results of this study, we infer that anaerobic condition due to the excessive accumulation of organic matters and lack of uniformity of water flow distribution are major factors of the low removal efficiency of the wetland.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.315-321
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• 2016

To identify the relationship between land use and thermal environment in an urban area, the air temperature was measured at different places of land use, and the changes of land use and air temperature were traced for 40 years in Incheon City. The relationship between land use and temperature was also investigated using satellite image data. The results of temperature measurements on a forest, a cropland (rice paddy), a bareland (school ground), and an urban area (asphalt road) from 19 to 21 August 2014 showed that air temperature was the highest on a pavement road. The temperature increased by about $1.4^{\circ}C$ ($0.035^{\circ}C/year$) for 40 years from 1975 to 2014 in Incheon. The changes in land use patterns of Incheon for the past 40 years showed that urban dry land, bareland and grassland have increased and cultivated land, wetland and forest land have decreased gradually. The land surface temperature (LST) was correlated with the normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI) extracted from Landsat satellite image. The land surface temperature was lower at higher NDVI, and higher at higher NDBI. Therefore, it is important to conserve and restore the land use of greenery, wetlands, and agricultural land in order to mitigate the heat island effect and improve the thermal environment in an urban area.