• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1616-1621
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• 2006

하천 지형은 흐름과 유사거동에 의한 세굴 또는 퇴적에 의하여 끊임없이 변한다. 이 연구에서는 최근 하천지형의 변화가 크게 일어나고 있는 한강 신곡수중보 직하류 우안의 고수부지 형성 이력에 대한 조사 및 분석을 실시하였다. 조사결과, 1981년 이전까지 하중도(제주초도)가 안정된 형태로 존재하였으나, 1980년대 중반을 거치면서 하중도는 소멸되었고 1990년대 중반 이후부터 우안에 비슷한 규모의 고수부지가 생성되었음을 알 수 있었다. 이 고수부지의 형성과정을 평가하면 다음과 같다. 1) 초기단계(흐름 변화에 따른 이동사주의 정지): 1995년 이전까지는 하천 내 자연적/인위적 교란에도 불구하고 이열사주 형태의 이동상이 유지되다가 1995년 이후 1988년 준공된 신곡수중보의 직.간접적인 영향을 받는다. 이로 인한 하중도의 소멸이 가중되면서부터 신곡수중보 직하류 우안의 이동사주가 정지하기에 이른다. 2) 성장단계(조석에 따른 부유사 반복 퇴적): 이동상 사주가 정지된 뒤 매일 2회씩 반복되는 조석의 영향을 받은 고농도의 부유사가 정지된 사주 위에 반복되어 퇴적되는 양상이 일어난다. 3) 정착단계(정지사주의 고수부지화): 정지사주에서 부유사가 퇴적하고 갈대와 같은 초본류 식생이 활착하게 되면서 부유사 퇴적은 가중되어 간다. 이러한 과정에서 1999년과 같은 대홍수 때 부유사의 고수부지 내 퇴적이 결정적이었을 것이다. 4) 확장단계(고수부지 확장단계): 대홍수 때 고수부지의 퇴적과 아울러 산재하던 버드나무가 교란을 받아 고수부지에서 새로운 버드나무 군락의 터전을 이루어 밀생하게 된다. 향후 고수부지가 잠기는 규모의 홍수가 빈발할 경우 퇴적층의 유실보다는 부유사 퇴적이 많아져 고수부지는 확장단계에 접어들게 된다.70{\sim}90$ 시간 동안 실험을 수행하였다. 세굴의 측정은 투명한 아크릴로 제작된 수제 내부에 CC카메라를 수제 전 후면 및 측면에 설치하여 월류수제의 세굴 발생을 실시간으로 측정하며 동시에 수제의 각 면에 각각 3개의 압력센서를 설치하여 압력분포를 측정함으로써, 월류수제 주변의 압력변화에 따른 세굴심의 실시간 변화를 비교할 수 있도록 하였다. 수심이 연중 $25{\sim}35m$를 유지하는 H호의 경우 간헐식 폭기장치를 가동하는 기간은 물론 그 외 기간에도 취수구의 심도를 표층 10m 이하로 유지 할 경우 전체 조류 유입량을 60% 이상 저감할 수 있을 것으로 조사되었다.심볼 및 색채 디자인 등의 작업이 수반되어야 하며, 이들을 고려한 인터넷용 GIS기본도를 신규 제작한다. 상습침수지구와 관련된 각종 GIS데이타와 각 기관이 보유하고 있는 공공정보 가운데 공간정보와 연계되어야 하는 자료를 인터넷 GIS를 이용하여 효율적으로 관리하기 위해서는 단계별 구축전략이 필요하다. 따라서 본 논문에서는 인터넷 GIS를 이용하여 상습침수구역관련 정보를 검색, 처리 및 분석할 수 있는 상습침수 구역 종합정보화 시스템을 구축토록 하였다.N, 항목에서 보 상류가 높게 나타났으나, 철거되지 않은 검전보나 안양대교보에 비해 그 차이가 크지 않은 것으로 나타났다.의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간은 24개월이하의 중단기가 적합함을

• Weed & Turfgrass Science
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• v.4 no.3
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• pp.188-198
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• 2015

This study was conducted in order to investigate the distribution pattern of weeds and ecological characteristics on the dry field in the Eastern region of Korea. The weed species data were obtained from 12 regions in Gangwon-do and Gyeongsang-do. 150 taxa were recorded from three main distinguished habitats; inside of dry field (IDF), embankment around the end of dry field (EDF), levee slope of dry field (LS). The weed species of three different habitats were IDF 83 taxa, EDF 133 taxa and LS 105 taxa. The species showing higher rNCD value was Portulaca oleracea in IDF, Digitaria sanguinalis in EDF and Humulus japonicus in LS. Compositae was dominant family followed by Gramineae, Polygonaceae and Leguminosae. Life form was distinguished as Th-R5-D4-e and three different habitats showed the same results. Disturbance index was analysed as IDF 83.1%, EDF 68.4%, and LS 62.9%. Naturalized rate was analysed as IDF 28.9%, EDF 22.6%, and LS 20.0%. These results indicate that the weeding management, land use intensity, and human interference effect on the distribution index and naturalized rate of weed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.157-168
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• 2014

From a complex systems perspective, ecohydrological systems in forests may be characterized with (1) large networks of components which give rise to complex collective behaviors, (2) sophisticated information processing, and (3) adaptation through self-organization and learning processes. In order to demonstrate such characteristics, we applied the recently proposed 'process networks' approach to a temperate deciduous forest in Gwangneung National Arboretum in Korea. The process network analysis clearly delineated the forest ecohydrological systems as the hierarchical networks of information flows and feedback loops with various time scales among different variables. Several subsystems were identified such as synoptic subsystem (SS), atmospheric boundary layer subsystem (ABLS), biophysical subsystem (BPS), and biophysicochemical subsystem (BPCS). These subsystems were assembled/disassembled through the couplings/decouplings of feedback loops to form/deform newly aggregated subsystems (e.g., regional subsystem) - an evidence for self-organizing processes of a complex system. Our results imply that, despite natural and human disturbances, ecosystems grow and develop through self-organization while maintaining dynamic equilibrium, thereby continuously adapting to environmental changes. Ecosystem integrity is preserved when the system's self-organizing processes are preserved, something that happens naturally if we maintain the context for self-organization. From this perspective, the process networks approach makes sense.

• Journal of The Geomorphological Association of Korea
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• v.17 no.2
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• pp.63-76
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• 2010

The Jangdo wetland is located on a very gentle slope of the mountain area in Daejangdo island, Shinan-gun, Korea, in which the area of the watershed is estimated at 147,000 m². The wetland has been regarded as a peat bog without any sedimentological evidence. This study was conducted to analyze the geomorphological and sedimentological characteristics of the wetland. The geographic information system (GIS) was used to analyze the drainage system, and field surveys were conducted to measure the range and depth of wetland deposits. The grain size analysis, organic matter determination, elements analysis and radiocarbon dating were performed on samples from the wetland. As a result, the wetland deposits were about 30 cm deep on average, the mean grain sizes ranged from 50 to 500 μm, and the average C/N ratio was 11.5. The portion of organic matter it contained was only 5~26%, which did not satisfy the peat standards. The radiocarbon ages from the wetland deposits range 180±50 ¹⁴C yr BP to modern, which indicated that natural and anthropogenic interferences including agricultural activities have continuously happened. We conclude that the Jangdo wetland is still in its infancy, not a steady state, so that it could be very sensitive to a small disturbance.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.287-304
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• 2007

This study was carried out to investigate spatio-temporal variations of benthic environment and macrobenthic polychaete communities in Gamak Bay where excessive organic matters from untreated sewage effluents and fish and shellfish farming activities have been accumulated in certain regions. Such environmental variables as sediment composition, organic content, acid volatile sulfide and dissolved oxygen content etc. were measured and polychaete specimens were taken in September 1999 and February 2000. In September 1999, organic contents were up to three times higher in the northwestern part of the bay and the area closed to Gukdong harbor than in the rest of the bay. In particular, benthic environment of the northwestern part of the bay was extremely deteriorated by the occurrence of hypoxia and highly concentrated sulfide. Of 28 stations investigated in summer, 5 stations located in the northwestern part were azoic. In the rest of the stations, a total of 119 polychaete species were sampled with a mean density of 900 $ind./m^2$. While species richness was higher in the entrance and central part of the bay where water exchanges with open sea were relatively active, density was higher in the moderately enriched stations neighbouring Gukdong harbor and fish farms where such potential indicators of organic pollution as Aphelochaeta monilaris, Lumbrineris longifolia were largely dominant. In February 2000, a total of 81 polychaete species appeared with a mean density of 2,802 $ind./m^2$ from 12 stations sampled in winter. Azoic areas were recolonized by Capitella capitata, Pseudopolydora paucibranchiata and Dipolydora socialis which showed maximum density in the innermost station. On the other hand, the rest of the stations were dominated by Euchone alicaudata and Praxillella affinis. The configuration of the stations sampled in summer and winter on the multidimensional scaling plots reflected the position of each stations within the bay in which there were great differences in organic content, sulfide concentration and oxygen content rather than in sediment composition. Therefore, heterogeneities in polychaete community structure in Gamak Bay were primarily influenced by the degree of the disturbance depending on the position within the bay.

• Journal of Korea Water Resources Association
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• v.45 no.5
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• pp.445-454
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• 2012

The present study aims to investigate the long-term channel morphological changes derived from channelization, embankment and levee construction works in unregulated fluvial channel of the Jiseock River. Analyses of aerial photographs taken past (Year 1966) and recent (Year 2002) showed the temporally remarkable changes in channel planform such as channel shape, bar migration, vegetation encroachment in bar. During the period, the natural single threading changed into braided types together with decreasing sinuosity by 9.2%, increasing vegetation occupied bar ranged 97% of total bars area. Because such channel morphological changes are closely similar to those in dam downstream channels, we assume that both/either flow regime alteration and/or sediment transport discontinuity may be critical for the fixed channel and spread of vegetated bars even in unregulated river without dam reservoir upstream. We found more reduced frequency and magnitude of flooding water level comparing with past, but no significant alteration of inter annual water level variation. Bed material has been coarsened by 4~5 times and the riverbed has been degraded in overall channel but aggraded locally in conjunction reach of tributaries. The results indicates that reduced sediment dynamics in fluvial channel which derived by bed material coarsening, river bed degradation and unbalanced sediment transport capacity between tributary and mainstem can be a causal factor to trigger channel morphological changes even in unregulated rivers.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.280-289
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• 2009

The fish communities and physical habitat conditions of fifteen tributaries of Lake Paldang in spring and autumn, 2008 were surveyed to evaluate the ecological health of the streams. The total 2,746 individuals were collected belonging to 11 families 31 genera 40 species. Two new species (Cottus koreanus, Gnathopogon strigaus) that have never been reported as yet in Lake Paldang watershed were found for the first time. The most dominant species in the tributaries was Acheilognathus yamatsutae (19.9%) which is Korean endemic species. Ecological health evaluation of fifteen tributaries using index of biological integrity (IBI) model for fish community and qualitative habitat evaluation index (QHEI) was performed. According th the IBI analysis, four streams (Siwoo-Stream, Jojong-Stream, Moonho-Stream and Mugab-Stream) were evaluated as "good" condition (B grade), Woosan-Stream were "poor" condition (D grade) and others were "fair" condition (C grade). Qualitative habitat evaluation index values of the four streams were the grade "II" indicating "good" condition and those of eleven streams were the grade "III", indicating 'fair' condition. On the whole, dataset of IBI and QHEI showed that ecological health of Jojong-Stream has been well maintained compared to other tributaries of Lake Paldang.

• Korean Journal of Environment and Ecology
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• v.22 no.2
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• pp.159-172
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• 2008

This study was carried out to obtain ecological information necessary for a conservation plan based on the distributional patterns, wetland types, and hydrophytic characteristics of urban wetlands in Seongnam City, Kyunggi Province where representing the various patterns of land use made by rapid urbanization since 1970s. Total 162 sites of four wetland types were identified as urban wetlands during the first survey. The sites were classified into 55 forested swamps, 4 riverine wetlands, 62 abandoned paddy fields, 37 small ponds, and 4 reservoirs, etc. The second survey targeted 107 sites which were identified as good wetlands. It showed that 42 sites(about 39%) were already degraded due to drainage, landfill, and crop cultivation at 6 months intervals. Both hydrologic conditions and hydrophytic characteristics of 27 good wetlands help maintain current ecological status, but most wetlands have been degraded by artificial impacts. Among 184 species identified, only 75 species(about 40.7%) were hydrophytes. Prevalence Index of hydrophyte based on three categories of OBL(obligatory wetland plant), FAC(facultitative plant), UPL(obligatory upland plant) was 3.7, indicating that vegetation data alone is inadequate to designate as wetlands. This study revealed that as critical habitats for wildlife they playa vital role in ecotone between both terrestrial and aquatic ecosystem with its proper distributional pattern in spite of their small areas compared to the entire geographic region of the City.

• Journal of Environmental Science International
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• v.12 no.12
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• pp.1207-1213
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• 2003

Osancheon creek is located in the southwest of the middle area in Korea. Weed community around the Osancheon creek, where various disturbances exert a bad influence directly on its community by human work or nature, was surveyed phytosocialogically. Our surveys have been accomplished from June, 2003 to September, 2003. Weed communities formed around the Osancheon creek were divided into several patterns and analysed. They have been divided into 8 communities. Community A: Humulus japonica community, B: Phragmites communiscommunity, C: Persicaria thunbergii community, D: Zi=ania latifolia community, E: Miscanthus saccharilflorus community, F: Echinochica crusgalli community, G: Typha orientalis community, H: Sataria viridis community. The flora surveyed in these communities was constituted of 19 families, 36 genera, 4 varieties, and 40 species. Wild plants such as Artemisia princeps var. orientalis Erigeron annuus, Bidens frondosa, Aeschynomene indica and Oenothera odorata were mostly light loving plants and higher resistant plants against the disturbance. Our result from the ranking all surveyed areas by the Bray-Curtis ordination method was very similar to the results from phytosocialogical table work.

• Korean Journal of Environment and Ecology
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• v.12 no.4
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• pp.331-344
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• 1999

To study plant community structure and successional sere of the Kojedo District, Hallyo-Haesang National Park, fifty six plots were set up and surveyed(each plot $l00\m^2$). Fifty-six plots were classified into four community, Quercus variabilis-Zelkova serrata community(I), Q. variabilis-Cinnamomum japonicum-Neolitsea sericea community(II), Pinus thunbergii-C. japonicum-N. sericea community(III), P. thunbergii-P. densiflora community(IV) by TWINSPAN technique. Most area of forests in Kojedo district are artificial or coppice forest after artificial disturbance. The age of four community were about 35~40 years and the number of species 32~44 species per $600\m^2$. Ecological succession had been proceeded from deciduous broad-leaved species(Q. variabilis-Z. serrata etc.), P. thunbergii, P. densiflora to evergreen broad leaved forest(C. japonicum, N. sericea etc.).