• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.166-180
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• 1998

In a city where the greenery always lacks landscaping roofs of existing buildings offers a way to solve the problem. But the most serious problem that poses is the matter of load limit. At present most existing buildings have the loading capacity of 200 kg/$m^2$ or less on their roofs. If the natural soil is used the loading capacity is easily surpassed because it simply is too heavy. To alleviate this problem it is realized to introduce the light weight artificial soil. The specific gravity of light soil is 0.65 whereas the natural soil is 1.8 when wet. It is three times lighter than the natural soil, thus eases the burden to the roof. The next problem to be confronted is the plant species to plant. It is possible to plant trees but they soon outgrow the loading capacity by weighing 8 times heavier in 10 years. Therefore shrubs and perennials are suggested to be planted because they don't weigh much even when they reach the mature height. The last problem is the stress put on roofs by the weight of the users. By some unexpected event the crowd gathered on a weak roof can cause the structural damage or even the collapse of the roof. The avoid the possibility of collapse a plaza or big pocket should not be designed in a roof garden because they hold crowd. By following the suggested means the old roofs of existing buildings can turn into the urban oases in the sky.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1469-1476
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• 2012

Hydrophilic polymer is suitable as soil conditioners for green roofs that use rainwater, due to promotion of water retention capacity as well as enhancement of the water absorbing capacity. The objective of the present study was to investigate the effects of different levels of hydrophilic polymer concentrations (0, 0.1, 0.2, 0.4, 0.8% w/w) on the water holding capacity and growth response of 6 species in soils amended with hydrophilic polymer in 5 cm of soil thickness on green roofs. The results showed that the water holding capacity of the amended soil improved with increasing amount of applied polymer. The application of 0.8% w/w of the polymer increased the soil moisture by 87% compared to the control, and decreased slowly in green roofs during an arid period. The growth of Sedum spurium 'Dragon's blood' and Lampranthus spectabilis increased significantly and had greater than 60% relative coverage with higher hydrophilic polymer concentrations. However, Juniperus chinensis var. sargentii and Euonymus fortunei var. radicans had no significant differences upon change of hydrophilic polymer concentrations. In Carex kujuzana and Carex morrowii 'Aurea variegata', growth decreased with increase of hydrophilic polymer concentrations. 30 days after planting, Juniperus chinensis var. sargentii, Euonymus fortunei var. radicans, Carex kujuzana, and Carex morrowii 'Aurea variegata' died back due to lowest soil thickness (5 cm), but Sedum spurium 'Dragon's blood' and Lampranthus spectabilis had greater than 90% survival.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.300-305
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• 2011

This study aimed at analyzing the runoff quality by the layer thickness and material of soil roof to make best use of the rainwater falling on it in terms of safety and efficiency and resulted in the following assessments. It turned out that the concentrations decreased more in T-N, $NO_3$-N, $NH_4$-N, T-P and $PO_4$-P in roof rainwater except 30 cm for the RW1 soil roof after passing through it than those of first rainwater. On the other hand, the concentrations in rainwater passing through gravel roof turned out to be equal or same to those of the first rainwater. As a result of analysis of metallic stuff in runoff, there was no indication of Cd, Cr, Mn and Pb as well. The concentration of Cu, Fe and Zn in rainwater through soil roof became less than that of the first rainwater. In this research, the soil roof showed the good efficiency in lowering the concentration of such components as nitrogen, phosphorus and metals. Based on the results from this work, more practical study would be required further in the future in relation to soil roof when installing the rainwater-utilizing facilities.

• Journal of Korean Living Environment System
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• v.21 no.6
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• pp.959-964
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• 2014

Energy performance of building envelope components, including external walls, floors, roofs, windows and doors, is crutial for determining how much energy is required for heating and cooling in a building. Among various building technologies, a green roof system can be a good option for reducing heat gain and loss in new buildings as well as existing buildings for green remodeling. This paper evaluates the performance of green roof systems according to soil depth and Leaf Area Index (LAI) for existing buildings. It also attempts to quantify the energy saving effects on new and existing buildings with different insulation levels. Thermal performance of green roofs is mainly dependent on soil thickness and LAI. Installation of green roofs in deteriorated existing buildings can lead to improvements in roof insulation, due to the soil layer. An increase in soil depth leads to a decrease in heating load, regardless of conditions of vegetation on the green roof. Larger LAI values may reduce cooling loads in the cooling season. Installation of green roof in deteriorated existing buildings showed bigger energy saving effect in comparison to a case in new buildings. A simulation study showed that the installation of green roof systems in deteriorated existing buildings with low insulation levels, due to low thermal performance requirements when constructed, could improve the energy performance of the buildings similar or better to the peformance on new buildings with the most updated insulation standard. Thus, when remodeling a deteriorated building, green roofs could be a good option to meet the most recent energy requirements.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.193-206
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• 2013

This study was to provide the base data on the status of vegetations and soils in green roofs by analyzing the soil and vegetation characteristics of 4 green roofs in Dongguk University in September 2012. Sanglokwon(SW), Dongguk Hall(DH), University Library(UL), and Information and Culture Hall P(IC) were established in 2005, 2008, 2009, and 2010, respectively. The areas of green roofs were $700m^2$, $2,300m^2$, $1,240m^2$, and $640m^2$ in SW, DH, UL, and IC respectively. The investigated floras of vascular plants were 26 families, 55 genera, 65 species in Sanglokwon(SW), 53 families, 99 genera, 112 species in Dongguk Hall(DH), 43 families, 77 genera, 84 species in University Library(UL), and 41 families, 71 genera, 75 species in Information and Culture Hall P(IC), respectively. A positive correlation is shown between the number of plant species and planting area. Total nitrogen, organic matter, and potassium in soil have positive correlation with the number of plant species. The number of plant species was proportional to area and increased more than twice after planting. About a quarter of the invaded plants (including native and naturalized species) were naturalized plants. The total soil depths including vegetation soil and drainage soil at SW, DH, UL, and IC were 20cm, 10cm, 10cm, and 8cm, respectively. The depths of vegetation soil at SW, DH, UL, and IC were <7cm, <3cm, <2cm, and <2cm respectively. The soil pH in vegetation soil ranged from 5.22 to 5.36, and from 6.13 to 6.39 in drainage soil. Available-P concentration ranged from 10.17 to 189.77mg/kg in vegetation soil and from 6.70 to 81.17mg/kg in drainage soil. Carbon concentration in vegetation soil ranged from 2.93 to 9.70%, and 2.93 to 9.70% in drainage soil. Carbon contents in 20cm, 10cm, 10cm, and 8cm soil depths were $2.62kg/m^2$, $1.89kg/m^2$, $0.50kg/m^2$, and $0.53kg/m^2$ at SW, DH, UL, and IC, respectively.

• Environmental Engineering Research
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• v.15 no.3
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• pp.167-172
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• 2010

The effects of low impact development (LID) techniques, such as green roofs and porous pavements, on the runoff and pollutant load from an apartment complex were simulated using the Site Evaluation Tool (SET). The study site was the Olympic Village, a preexisting apartment complex in Seoul, South Korea, which has a high percentage of impervious surfaces (approximately 72% of the total area). Using the SET, the effects of replacing parking lots, sidewalks and driveways (37.5% of the total area) having porous pavements and rooftops (14.5% of the total area) with green roofs were simulated. The simulation results indicated that LID techniques reduced the surface runoff, and peak flow and pollutant load, and increased the evapotranspiration and soil infiltration of precipitation. Per unit area, the green roofs were better than the porous pavements at reducing the surface runoff and pollutant loads, while the porous pavements were better than green roofs at enhancing the infiltration to soil. This study showed that LID methods can be useful for urban stormwater management and that the SET is a useful tool for evaluating the effects of LID on urban hydrology and pollutant loads from various land covers.

• Journal of Environmental Science International
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• v.24 no.7
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• pp.927-937
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• 2015

This study was performed to identify and quantify the asbestos fibers released from two types of asbestos-cement slate roofs. One is a plant roof installed in 1987 which contained 15% chrysotile, and the other is a residential roof installed before 1983 which contained 12% chrysotile. The concentrations of asbestos fibers in air surrounding asbestos-cement slate roofs and in the falling water harvested from the same roofs on rainy days ranged from 0.0012 to 0.0018 f/mL and from 1,764 f/L to 10,584 f/L, respectively. The concentration of inorganic fibers in the soil around asbestos-cement slate roofs was from 217 to 348 f/g. With the above results, the excess lifetime cancer risk (ELCR) for the risk assessment of the asbestos fibers released from asbestos-cement slate based on US EPA IRIS (Integrated risk information system) model is within 5.5E-06 ~ 6.5E-06 levels which indicates that the levels do not exceed "the acceptable risk(1.0E-05)" recommended by WHO. The asbestos concentration in air, drained rainfall and soil around the plant slate roof was higher than that around residential slate roof, but the excess lifetime cancer risk (ELCR) from residential slate was higher than that from plant slate. This suggested that the enclose and encapsulation of residential roofs have priority in removal policy to minimize the exposure risk.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.6
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• pp.109-117
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• 2013

This study was carried out to investigate the changes of plant species and soil physicochemical properties on green roofs established at Seoul Women's University in 2005, 2006 and 2007. The plant species and soil properties were investigated in 2013. The areas of green roof sites ranged $90{\sim}100m^2$. There were floras of vascular plants of 12 families, 20 genera and 22 species in the 2005 site, 24 families, 37 genera and 38 species in the 2006 site, 14 families, 27 genera and 31 species in the 2007 site. The total number of plant species decreased in the 2005 and 2006 sites and increased in the 2007 site since established. High proportion of dispersal type was barochory in the 2005 and 2006 site, and autochory in the 2007 site. And the proportion of the compositae family was high in the introduced plants over the sites for the all study sites. Average pH and organic matter concentration of green roof soil were ranged from 5.25 to 5.96 and 7.17 to 8.96% in study sites. The organic matter concentration and pH of green roof soil were lower in 2013 than in the three establishment years. Carbon concentration of green roof soil in the three study sites were ranged from 4.16 to 5.30% and total soil carbon in 10cm depth were ranged form 1.57 to $1.98kg/m^2$.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.5
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• pp.110-120
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• 2009

The hipped roof on the research building, which was constructed 51.9m above sea level on a hillock by Korea National University of Education in June 1999, is composed of four inclined planes which are 12m in breadth, 8m in length and have a 30 degree gradient. For the roof vegetation, the yellow earth collected from around the building was laid on top. It was designed to supply the soil on the slope with water for a considerable period by making rainfall pool at the edges. In order to prevent the soil on the slope from being swept away, 31 sorts of grass seeds were imported from Germany and sown in the soil. At the present day, 10 years after the seeds began to sprout and inhabit the settled slope, 30 individual plant species were identified in the period between April 2008 and March 2009. Out of 31 species were seeded on the slanted, soiled roof, only 8 were still alive. It was confirmed that the Artemisia Princeps var, Chrysantheum, Prunella Vulgaris and Lespedeza Cuneata have been the major species inhabiting the east, west, south and north inclined planes respectively. The Phragmites Communis was inhabiting the edge of the roof where the water supply was adequate, while the Dianthus Barbatus was primarily inhabiting the south-east side of the roof. As a whole, 26 identifiable plants and 4 unidentified plants were observed on the inclined planes of the hipped roof. In consideration of the plant distribution on the slope, it was confirmed that the selection of seeds may have had an effect on the slope vegetation. As for the yellow earth laid on the roof, it was discovered that about 2~3cm thickness around the ridge was swept away, but the rest of the slope was in relatively good condition. Accordingly, it has been proven that vegetations can be applied to hipped roofs by using ordinary plants without any special structural measures.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.6
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• pp.45-58
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• 2005

The objective of this study is to the integrated evaluation of the present condition and satisfaction of visitors of rooftop greening area using quantitative and qualitative method. The thirteen green roofs were selected to investigate environmental variables as like building structure, soil, water, atmosphere and climate environment and questionnaire survey for investigate the satisfaction of visitors was conducted. The results of this study are as follows : remove of the hazardous inflow of species, install rain water recycling facility, install outdoor unit of air condition where not to affect plants in green roof, install safety facilities in the case of making resting place, plant variable vegetation and so on. The result of questionnaire survey are that visitors want to make more comfortable resting space. The more bigger the resting space and privacy, the more satisfaction of visitor became high. In conclusion, green roofs implementation should be considered reduction of temperature and delay of runoff, insulation effect and ecological restoration as well as rooftop greening is focused on the development of resting space nowadays.