• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.449-455
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• 2019

The increase in impermeable pavement from recent urbanization has resulted in an increase in surface runoff. The surface runoff has also increased the burden of the existing drainage system. This drainage system has structural limitations in that the catchment area is reduced by the waste particles transported with the surface runoff. In addition, the efficiency of the drainage system is decreased. To overcome these limitations, a new type of drainage system with a drainage layer was developed and applied. In this study, various volume porosity and permeability of the lower drainage layer were simulated using ANSYS CFX, which is a three dimensional computational fluid dynamics program. The results showed that the outlet velocity of the 35% volume porosity was faster than that of the 20% and 50% cases, and there was no relationship between the volume porosity and drainage performance. The permeability of the drainage layer can be determined from the particle size of the material, and a simulation of five conditions showed that 2 mm sand grains are most suitable for workability and usability. This study suggests appropriate values of the volume porosity and particle size of the drainage layer. This consideration can be advantageous for reducing and preventing flood damage.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.136-142
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• 2019

Water spider(Argyroneta aquatica) inhabits only a small size wetland in Eundae-ri, Yeoncheon-gun. In this study to investigate environmental factors influencing on population of A. aquatica, we analyzed the relationship between density of A. aquatica and various physicochemical and biological factors. Density of A. aquatica increased with small habitat area and high $NH_4$ and electric conductivity. The relationship between density of A. aquatica and prey or predator was low but the water spider decreased with density of Pomacea canaliculata. And density of A. aquatica was not related to the coverage of emergent plant. However density of A. aquatica decreased as the increase of floating plant and increased as the increase of submerged plant. These results indicated that aquatic plants are important in the habitat environment of A. aquatica. Therefore we suggest necessity of management strategies for the invasive species, P. canaliculata which is a notorious predator of aquatic plants.

• Journal of the Korean GEO-environmental Society
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• v.23 no.3
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• pp.15-22
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• 2022

This study aims to observe the swelling representative rocks in Korea and to suggest improvements in the use of test methods and prior analysis in relation to the weathering of rocks. The swelling test and analysis were performed on the drilling cores obtained for the ground investigation at the domestic highway construction site. For the method of determining the absorption expansion index of rocks, the method proposed in "Standard Methods for Sample Collection and Specimen Preparation" of ISRM and Korean Rock Engineers Standard Rock Test Method was used. The specimen for the measurement of the expansion displacement was cylindrical with a height of 10 cm and a diameter of 5 cm. The existing swelling analysis method evaluates the sensitivity to weathering by using the maximum expansion displacement, but since the classification by bedrock grade is unclear, it is reasonable to use the rate of change of the expansion displacement according to the immersion time. It is necessary to conduct an experiment to distinguish between weathering and fault deterioration. In addition, long-term weathering prediction technology for each cancer type is needed through the expansion displacement analysis of the chemical weathering stage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.333-342
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• 2022

Due to climate change, increased heavy rainfalls result in flood damage every year. To investigate the storm-runoff reduction effects of Low Impact Development (LID), this study performed runoff analyses using the U.S. Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) for past and future representative storm events of the Yongdu Rainwater Pumping Station basin. As a result, the infiltration loss for representative future rainfalls increased by 3.17 %, and the surface runoff and peak runoff rate increased significantly by 32.50 %, and 128.77 %, respectively. To reduce the increased surface runoff and peak runoff rates, this study investigated the applicability of LID approaches, including a permeable pavement, green roof, and rain garden, by adjusting the LID parameters and the ratio of installation area. We identified the ranges of LID parameters that decreased peak runoff rate and surface runoff, and increased infiltration. In addition, when the application ratio of permeable pavement, green roof, and rain garden was 2:1:3, best performance was attained, leading to a reduction of peak runoff of 26.85 %, infiltration loss 12.01 %, surface runoff 15.11 %, and storage 509.47 %. Based on analyzing the effect of storm runoff reductions for various return periods, it was found that as the return period increased, the proportion of peak runoff and surface runoff increased and the proportion of infiltration loss and storage decreased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.179-186
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• 2006

Effective interception area of street grate inlets was decreased by clogging with trash, debris, and sand. It also decreased the interception capability of grate inlets and increased the inundation area in street. Therefore, it is necessary to analyze the clogging characteristics and interception capability change by clogging for appropriate design and management of grate inlets. Hydraulic experimental apparatus which can be changed the gutter transverse slopes, longitudinal slopes of street and clogging condition of grate inlet ($40{\times}50cm$) was installed for this study. 81 total experiments were conducted with 8 different clogging condition. The interception capacities of grate inlets clogged curb direction are smaller than those of clogged flow direction. As the longitudinal slopes of street increase, the interception capacity of grate inlet decreases due to splash-over phenomena. This is also observed at grate inlets which has no clogging condition. In general, 50% of clogging factor was selected in design of grate inlet in foreign country. The clogging factor for same clogging condition are suggested 0.25~0.65 in domestic urban area.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.2
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• pp.60-68
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• 2008

Three land-use limitations including water hazard, soil erosion and fallow potential were evaluated to define an unfair area. Landscape indices in the unfair areas, defined by evaluations before and after landscape enhancement, were computed by Fragstats v3.3 and compared in order to propose a landscape enhancement plan. The results are as follows: First, as a result of the land evaluation, 388.56ha was analyzed for the 1st class(S1), 623.25ha for the 2nd class(S2), 138.08ha(S3s: 82.47ha, S3e: 51.88ha) for the 3rd class(S3), 230.44ha(N1w: 194.91ha, N1e: 23.09ha, N1es: 13.94ha) for the 4th class(N1), and 67.91ha(N2w: 60. 89ha, N2es: 7.02ha) for the 5th class(N2). The classes under the 3rd class(including the 3rd class) were determined as an unfair area, and proposed landscape enhancement for them. Second, it was proposed that unfair areas with potential water hazards(N1 w, N2w) be restored as a wetland and buffer zone. At this point, the farmers owning these fields could be compensated using the direct payment for landscape conservation(DPLC). Areas witha relatively lower slope(S3e) or a steep slope(N1e) containing soil erodibility potential were proposed to be restored as a sod-culture-applied field and substitute vegetation or potentially natural vegetation, respectively. The unfair areas having fallow potential(S3s, N1es, N2es) were proposed to apply special use crops for the S3s fields, native plants for the N1es fields, and intended fallow for the N2es fields. Third, after landscape enhancement, theforest had higher values in the indices of NP, PLAND, LSI, IJI, and TCA, while paddy and upland had lower values in most indices except NP and LSI. The forest patches increased and were more plentiful with their restoration and had much greater possibility to join with nearby patches. With continued restoration, forest patches will have a large core area and small number of patches due to the conglomeration of patches, which positively influences the species of diversity in the forest patches.

• Journal of Wetlands Research
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• v.7 no.3
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• pp.87-95
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• 2005

Vegetation structure of the vascular plants was investigated from March 2003 to October 2003 in Haepyeong wetland, Gumi-si, Gyeongsangbuk-do, Korea. Actual vegetation of Haepyeong wetland largely can be classified by floristic composition and physiognomy into 18 communities; Xanthium strumarium-Digitaria sanguinalis, Humulus japonicus, Persicaria perfoliata-Humulus japonicus, Phragmites japonica-Miscanthus sacchariflorus, Persicaria hydropiper-Phragmites communis, Persicaria hydropiper, Phragmites japonica-Persicaria hydropiper, Miscanthus sacchariflorus- Phragmites japonica, Persicaria hydropiper-Phragmites japonica, Miscanthus sacchariflorus-Salix glandulosa, Salix nipponica-Salix glandulosa, Salix nipponica-Salix koreensis, Salix nipponica, Miscanthus sacchariflorus-Salix nipponica, Phalaris arundinacea-Salix nipponica, Salix glandulosa-Salix nipponica, Trapa japonica, and Ceratophyllum demersum-Trapa japonica. Among them, the area of the Salix nipponica-Salix koreensis community was the largest as 122.2ha(9.23%). The dominant vegetation type was Miscanthus sacchariflorus-Persicaria hydropiper community based on phytosociological method, and it was was classified into three subcommunities; Salix glandulosa-Salix nipponica subcommunity, Digitaria sanguinalis subcommunity, and Cyperus amuricus subcommunity. Differential species of Salix glandulosa-Salix nipponica subcommunity were Salix nipponica, S. glandulosa, S. koreensis, Scirpus radicans, Persicaria maackiana, and Achyranthes japonica; differential species of Digitaria sanguinalis subcommunity were D. sanguinalis, Setaria viridis, Ambrosia artemisiifolia var. elatior, and Cyperus orthostachyus; differential species of Xanthium strumarium subcommunity were X. strumarium, Acalypha australis, Erigeron canadensis, Echinochloa crus-galli, and Vicia tetrasperma. Zonation of vascular hydrophytes and hygrophytes was as followers: Salix glandulosa, S. koreensis, S. nipponica were distributed in the region of land which water table is low, and Persicaria maackiana, Persicaria hydropiper, Scirpus radicans were distributed in the understory. And emergent plants such as Phragmites communis and Scirpus karuizawensis, floating-leaved plant such as Trapa japonica, submersed plant such as Ceratophyllum demersum, and free floating plant such as Spirodela polyrhiza formed the zonation from shoreline to water. The specified wild plants designated by the Korean Association for Conservation of Nature, Ministry of Forest, and Ministry of Environment were not distributed in the study area. It was expected that Haepyeong Wetland worthy of conservation contributed purifying water pollution, giving habitats of many lifes, and providing beautiful scenes of the river.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.589-599
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• 2014

This study selected optimal sites in Myeongsasimni located in west coast of Korea for stratigraphic research containing extreme climate event during quaternary period by spatio-temporal analyses of changes in sedimentary environment and land use employing 1918 topographic map, 2000 digital terrain map, 1976 and 2012 air photographies. The study area shows no significant changes in topographic characteristics that hilly areas with relatively large variations in elevation are distributed over north and south part of the study area, and sand dues are developed along the coast line. Moreover, flat low lying areas are located at the back side of the sand dues. The movement of surface run off and sediment loads shows two major trends of inland direction flow from back sides of sand dunes and outland direction flow from high terrains inland, and the two flows merge into the stream located in the center of the study area. Two sink with individual area of $0.2km^2$ are observed in Yongjeong-ri and Jaryong-ri which are located in south central part and south part of the study area, respectively. In addition, sea level change simulation reveals that $3.4km^2$ and $3.64km^2$ are inundated with 3 m of sea level rise in 1918 and 2000, respectively, and it would contribute to chase sea level change records preserved in stratigraphy. The inundated areas overlaps well with sink areas where it indicates the low lying areas located in south cental and south part of the study area are identical for sediment accumulation. The areas with minimal human impact on sediment records over last 100 years are $3.51km^2$ distributed over central and south part of the study area with the land use changes of mud and rice field in 1918 to rice field in 2012. The candidate sites of $0.15km^2$ in central part and $0.09km^2$ in south part are identified for preferable locations of geologic record of extreme climate events during quaternary period based on the overlay analysis of optimal sedimentary environment and land use changes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.70-80
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• 2011

Estuarine ecosystem responds sensitively to natural and anthropogenic perturbations. lt is necessary to identify the direction of the change when the perturbation occurs as well as to understand the structure and functioning of estuarine ecosystem for a proper management of the area. In this study, the estuarine habitats were classified into different ecological districts so as to the switch from one district to another district could be related to the environmental change due to the perturbations. Total 16 ecological districts was defined according to the presence of barrage, salinity and vegetation characteristics. The defined ecological districts were applied to small estuaries in Goseong bay, south sea of Korea (Baedun, Guman, Maam, Goseong) to distinguish different regions which might have characteristic bottom topography, inclinations of river bottom, sediment characteristics, salinity structure and area of vegetation. Total 7 out of 16 ecological district was identified in this region; NFB (natural, fresh, bare), NHB (natural, high salinity, bare), NLV (natural, low salinity, vegetated) in natural (without barrage) estuaries and CFB (closed, fresh, bare), CFV( closed, fresh vegetated), CLV (closed, low salinity, vegetated), CHB (closed, high salinity, bare) in closed (with barrage) estuary. A comparison of environmental factors and biota between CHB and CLV demonstrated the effect of barrage on estuarine ecosystem. The height and sediment characteristics of CHB and CLV were similar but the average salinity was lower in CLV than in CHB due to the barrage, which produced favorable condition for the Phragmites australis in CLV. Information regarding the ecological districts in various sizes and location could be useful for predicting the ecosystem change due to natural and anthropogenic perturbations and for preparing management actions.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.201-237
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• 1992

본(本) 연구(硏究)는 1992년(年) 2월(月)부터 동년(同年) 8월(月)까지 한국(韓國)의 농어촌진흥공사(農漁村振興公社)(RDC)와 말레시아의 KTA기술용역단간(技術用役團間)의 기술제휴하(技術提携下)에 아세아개발은행(亞細亞開發銀行)의 기술협력기금(技術協力基金)에 의(依)한 말레지아북부(北部) Terengganu 농촌개발제(農村開發第)2단계사업(段階事業)의 타당성조사연구(妥當性調査硏究) 결과(結果) 중 말레시아정부(政府)의 경제정책방향(經濟政策方向), 농업개발(農業開發) 및 사업(事業)의 경제적(經濟的) 재무적(財務的) 타당성(妥當性)만을 발췌(拔萃)하여 본(本) 논문(論文)에 수록(收錄)하였다. 본(本) 농촌개발사업지구(農村開發事業地區)는 말레시아의 북동(北東)쪽에 위치(位置)하고 있는 Terengganu State의 Setiu-Besut양(兩) Distict가 포함(包含)되는데 경제적(經濟的)으로 가장 낙후(落後)된 지역(地域)으로 매년(每年) 행사(行事)처럼 찾아오는 홍수(洪水)때문에 농경지(農耕地)를 집약적(集約的)으로 경작(耕作)하지 못함으로써 지역농민(地域農民)들은 빈곤(貧困)에서 벗어나지 못하고 있고 침수기간중(浸水期間中)에는 지역(地域)의 경제활동(經濟活動)은 물론(勿論) 교통(交通)마저 불통(不通)되고 농촌하부구조(農村下部構造)의 손실(損失)은 물론(勿論) 사회경제적(社會經濟的)인 손실(損失)이 크며 Setiu River의 하구(河口)가 침전(沈澱)되어 어선(漁船)의 출입(出入)이 점점(漸漸) 곤란(困難)해지므로써 어민(漁民)들의 생계(生計)에도 위협(威脅)을 주는 지역(地域)이다. 따라서 본(本) 타당성(妥當性) 조사연구(調査硏究)의 근본적(根本的)인 목적(目的)은 농촌(農村)의 빈곤(貧困)을 타파(打破)하기 위하여 (1) 홍수(洪水)를 방지(防止)하고, 배수(排水) 및 관개개선(灌漑改善)을 하며, 하구(河口)를 개발(開發)하여 어민(漁民)들의 생산활동(生産活動)을 돕고 지역주민(地域住民) 및 농민(農民)들의 경제활동(經濟活動) 및 농업생산성(農業生産性)을 제고(提高)시키며 (2) 환경보호(環境保護) 및 관리(管理)를 통(通)하여 지역주민(地域住民)에게 쾌적(快適)한 농촌생활환경(農村生活環境)을 제공(提供)하고 생태계(生態系)의 변화(變化)를 방지(防止)하며 (3) 다각적(多角的)인 영농활동(榮農活動)을 통(通)하여 지역농민(地域農民)의 소득(所得)을 극대화(極大化) 할 수 있는 개발(開發)의 기본구상(基本構想)과 이에 대한 기술적(技術的) 경제적(經濟的) 타당성(妥當性)을 구명(究明)하는 것이다. 본(本) 사업지역(事業地域)의 총면적(總面積)은 9,500ha이며 이는 4,680ha의 기설지구(旣設地區)의 개보수관개사업(改補修灌漑事業)과 500ha의 과수단지(果樹團地), 200ha의 채소단지(菜蔬團地), 500ha의 옥수수단지(團地), 250ha의 엽연초생산단지(葉煙草生産團地), 2,760ha의 오일팜 및 고무나무단지에 소, 염소 및 양(洋)을 사육(飼育)하는 종합적(綜合的)인 농촌개발(農村開發)로서 농가(農家)의 농업소득제고(農業所得提高)에 큰 기여(寄與)를 하게 되며 Setiu강(江)의 유역(流域) 4,090ha에 대한 홍수경감대책(洪水輕減對策)으로 지역주민(地域住民)의 생활안정(生活安定) 및 교통(交通), 관광(觀光), 사회경제적(社會經濟的) 생산활동(生産活動)을 촉진(促進)하는 사업(事業)을 하게된다. 본(本) 사업(事業)의 공사기간(工事期間)은 1993년(年)부터 5개년간(個年間)이며 총사업비(總事業費)는 외화(外貨) 2천만불(千萬弗)을 포함(包含)하여 5천(千) 5백만불(百萬弗)로 추정(推定)되었다. 년간사업수익(年間事業收益)은 사업(事業)의 완전운영기간(完全運營期間)인 2003년(年)을 기준(基準)으로 할 때 15,541백만불(百萬弗)로 추정(推定)되었으며 사업(事業)의 내구기간(耐久期間)은 30년(年)으로서 2023년(年)까지 생산(生産)이 계속(繼續)될 것이다. 본(本) 사업(事業)의 전체재무수익율(全體財務收益率)은 22.49%이며 경제적(經濟的) 수익률(收益率)은 19.30%로 경제적(經濟的)인 타당성(妥當性)이 매우 높음을 알 수 있다. 모든 사업(事業)이 계획(計劃)대로 성공적(成功的)으로 추진(推進)될 경우 사업지역내(事業地域)의 몽리농가(蒙利農家) 4,000호(戶)가 큰 혜택(惠澤)을 보게되고 농촌(農村)의 빈곤수준(貧困水準)(Poverty Line)은 현재(現在)의 36%에서 18%수준(水準)으로 경감(輕減)될 것이 기대(期待)되고 있다.