• Journal of Ecology and Environment
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• v.34 no.2
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• pp.175-191
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• 2011

Colonization patterns and community changes in benthic macroinvertebrates in the Cheonggye Stream, a functionally restored stream in downtown Seoul, Korea, were studied from November 2005 to November 2007. Benthic macroinvertebrates were quantitatively sampled 15 times from five sites in the stream section. Taxa richness (59 species in total) increased gradually over the first year, whereas the density revealed seasonal differences with significantly lower values in the winter season and after flood events. The benthic macroinvertebrate fauna may have drifted from the upstream reaches during floods and from the Han River, arrived aerially, or hitchhiked on artificially planted aquatic plants. Oligochaeta, Chironommidae, Psychodidae, and Hydropsychidae were identified as major community structure contributors in the stream. Swimmers and clingers colonized relatively earlier in the upper and middle reaches, whereas burrowers dominated particularly in the lower reaches. Collector-gatherers colonized at a relatively early period throughout the stream reaches, and collector-filterers, such as the net-spinning caddisfly (Cheumatopyche brevilineata), predominated in the upper and middle reaches after a 1-year time period. Cluster analyses and multi-response permutation procedures demonstrated that the Cheonggye Stream shares more similarities with the Jungnang Stream than with the Gapyeong Stream. Detrended correspondence analysis and nonmetric multidimensional scaling demonstrated that physical environmental factors (depth, current velocity, dissolved oxygen, and pH) as well as nutrients (total nitrogen and total phosphorous), water temperature, and conductivity could affect the distribution of benthic macroinvertebrates in the study streams.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.234-243
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• 2007

Algal growth potential (AGP) test was performed to evaluate the water quality and changes in phytoplankton communities before and after a heavy rain event at six sampling sites in Cheonggye Stream (St. 1 and 2), Jungnang Stream (St. 3 and 4), and Lower part of Han River System (St. 5 and 6) after rehabilitation of Cheonggye Stream, October 2005. To test AGP on each sampling site, cyanobacterium Microcystis aeruginosa was applied as a standard alga. Total nitrogen (TN) showed high values at Jungnang Stream, while St. 4 recorded highest values in this study. However, TN values of Cheonggye Stream and Lower Part of Han River showed similar levels. Total phosphate (TP) also showed high values at Jungnang Stream, while St. 4 recorded highest. However, TP in Cheonggye Stream were extremely low levels. Although chlorophyll-${\alpha}$ (chi-${\alpha}$) contents before the rain event were similar through the sampling sites, chl-${\alpha}$ after the rain increased dramatically at Jungnang Stream and Lower part of Ban River. In particular, after the rain, TP was the highest at St. 4, where Cyclotella sp. dominated the phytoplankton community. When compared with control, AGP values before the rain were comparatively low in all sites, while those after the rain highly increased with the dose-dependently of field water added, due perhaps to the increased nutrients by rainfall. Similar results were observed in Cheonggye Stream. Therefore, for the aesthetic fostering for the citizens, although Cheonggye Stream was Presently being sustained by treated water supply, they have a potential of outbreak of phytoplankton by the increased nutrients supply when a heavy rain comes.

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.130-137
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• 2012

This study has conducted to develop new gabion wall systems with vegetation base materials for stream bank stability and rapid rehabilitation. Vegetation base materials are primarily compounded with fine soil, organic composts and peat moss as plant fibers, a water retainer and a soil improver. Normally gabion wall systems resist the lateral earth pressures or stream power by their own weight. Therefore, fill material must have suitable weight, compressive strength and durability to resist the loading, as well as the effects of water and weathering. In this project, 100 to 200-mm clean, hard stones are basically specified, and about 50-mm rubbles are also used. Test application of new gabion wall system carried out in the stream bank of a small stream in the Gwangreung experimental forest, belonging to Korea Forest Research Institute (KFRI) in December 16th, 2006. As a result of the analysis of hydraulic stability of new gabion wall system, gabion wall system has highest threshold shear stress when the gabion wall covered by vegetation. New gabion wall system is highly resistant to sliding and overturning because safety coefficients exceed 1.5. As a result of term of slope stability analysis of new gabion wall system by Bishop and Fellenius methods, stability of stream bank was highly increased after the construction of gabion wall. Therefore, new gabion wall system is effective to stabilize unstable stream bank.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.374-381
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• 2008

Spatial and temporal changes of fish communities were studied at four study sites in the Cheonggye Stream from October 2005 to August 2006 after the rehabilitation process. During the survey period, 19 species in 6 families were sampled. Species Rhynchocypris oxycephalus and Zacco platypus were identified as dominant species. Korean endemic species such as Acheilognathus yamatsutae and Zacco koreanus were observed in the sites. Overall, species richness and abundance increased as time passes after the rehabilitation, reflecting colonization process of the fish community. Meanwhile species richness and abundance were higher at the downstream than at the upstream. Community indices such as dominant index, richness index and diversity index showed also similar spatial and temporal pattern. Nonmetric multidimensional scaling (NMDS), multivariate ordination technique, was used to analyze spatial and temporal variation of the fish communities, and the results showed spatial variation of fish communities with high species richness at downstream as well as the temporal variation of fish communities with high values of species richness and diversity index at later part of the study period, presenting colonization process of the fish community after the rehabilitation project.

• Journal of Environmental Impact Assessment
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• v.19 no.2
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• pp.127-140
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• 2010

This study investigates the relation between the location of a habitat and the ecological connections according to the habitat type in the riparian zone at the Nonsan Stream and Yanghwa Stream. Stream habitat is classified into nine types for the aquatic insects and fish. For vegetation and birds, habitat is classified into two types of medium-scale streams, including both physical and chemical streams are analyzed accordingly. Nowadays, The fundamental goal of the river environment restoration enterprise is the rehabilitation or the restoration of the characteristic the river scenic or environment. For instance, The Channel habitats which has physical nature environment such as flat, speedy rapids, or closed-channel wetland, pool are constructed by artificial, Consequently, make them autogenesis smoothy eco-environment. However, the river environment are controlled not only physical environment, but it also need reasonable the quality of the water to compose smoothly. Finally, understanding what influence are effecting on physical habitat environment which are made by natural factors to water quality are very important factor for the river environment restoration enterprise Therefore, In this research, we are targeting to a basin to investigate the environment of the physical channel habitat and evaluate the changing of the water quality. This results will be a important characteristic that can judge the physical habitat and reciprocality connected to the water quality or adequacy of restoration technology. Therefore in this study, as a step to quantify functions and values of habitats and definite factors to perform habitat, we selected a representative stream of sand-stream, gravel-stream to classify habitat characteristics and quantified the physical, chemical, biological characteristics.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.242-254
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• 2010

Streams changed by artificial factor those support positive functions but also negative function to humanbeing. Time and pathway exceed the lost of structure and negative function appearing as disturbance. Therefore, it is desirable to prepare right situation to break of a vicious circle. Stream ecology was evaluated with using ichthyofauna during three years at the three disturbed sites and reference sites in Nakdong River. Forty-one species belonging three orders and ten families were identified in six surveying sites of Nakdong River during 2007~2009. Korean endemic species (14 species, 34.1%) and alien (3 species, 7.3%) were identified in Nakdong River ichthyofauna. Species number, species diversity, ecosystem structure and habitat variability of ecosystem were applied to evaluate stream ecosystem. In view of three year comprehended data at six sites; numeric instability appeared Andong Dam and Naeseongcheon sites worse than Gamcheon and reference site, otherwise more numeric diversity appeared Gamcheon and reference site than Andong Dam and Naeseongcheon. As a result of integration, sand stream including downstream of Andong dam, Naeseongcheon and Gamcheon has been having more diversified biodiversity and habitat diversity than those in the pebble stream.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.21-28
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• 2007

This study was conducted to investigate how the qualities of the stream water vary during the event in the regrowth and rehabilitation catchments in Yangju, Gyeonggido, from June to September 2005. During the observation periods, we sampled the stream water continuously by an auto-sampler (ISCO, 6712FR). The sampled waters were analyzed for suspended solid concentration, electrical conductivity and pH. The suspended solid concentration during the event increased concurrently with the stream flow. The peak of suspended solid concentration usually precedes the peak flow. The maximum value of suspended solid concentration was 420.89 mg/l in the event 1 at the regrowth catchment. Among the events simultaneously sampled at both catchments, the maximum values of suspended solid concentration were 212.8 mg/l and 58.24 mg/l in the event 3 at the regrowth and rehabilitation catchment respectively. The maximum value of EC in each event showed in the early stage of rising limb. EC decreased during the rising limb, and then showed minimum value at peak flow. EC gradually increased to pre-event value after minimum one. pH varied in similar pattern with EC. The maximum value of suspended solid concentration during each event was 2.8 to 4.3 times higher at the regrowth catchment than at the rehabilitation catchment. And the EC during each event was higher at the regrowth catchment than at the rehabilitation catchment. This results indicate that a disturbed forest soil during clear cutting at regrowth catchment still has been unstable.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.157-165
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• 2007

Currently, there are two major problems in professional engineer(PE) licensure system in Korea to be accredited internationally. One is a incompleteness of system connecting the licensure and the accredited engineering education program and the other one is a insufficient working experience condition required for achieving PE license. Therefore, these two problems are setbacks hindering Korea's PE license accredited internationally. In this study, international tendency stream on mutual accreditation of PE license are reviewed first, and the PE licensure system of the major countries are compared and analyzed. Based on the results, requirements improvement plan are suggested and the gradual implementation method are suggested also.

• Korean Journal of Environment and Ecology
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• v.27 no.6
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• pp.695-703
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• 2013

The fish fauna and population Zacco koreanus in the Cheonggye stream after the rehabilitation was investigation from April 2011 to May 2012. The collected species during the survey period were 24 species belonging to three families. Among them, Korean endemic species such as Rhodeus uyekii, Acheilognathus yamatsutae, Acheilognathus gracilis, Squalidus japonicus coreanus and Zacco koreanus were observed in the stations. Dominant species was Zacco platypus (St. 1, 3, 4) and Z. koreanus (St. 2). A total of species of A. gracilis, Hemibarbus longirostris, Gnathopogon strigatus, S. japonicus coreanus, Pseudogobio esocinus, Erythroculter erythropterus, and Tridentiger brevispinis were first observed this study with compared the previous data (2005, 2008). It seems that the introduction species of artificially to the Cheonggye stream were Cyprinus carpio (fancy carp), Carassius auratus (gold fish), Carassius auratus (chinese carp), Zacco temmincki, Z. koreanus and Misgurnus mizolepis. Calculation of the length-weight relationship of Z. koreanus showed the value of constant a as 0.000007 and b as 3.58, and condition factor (K) was 0.82 on average. The frequency analysis of total length indicated that the group 20~80mm in total length is represented by one year-old individuals, the group 90~120mm by two year-old individuals, and the group over 130mm by three year-old individuals. It is assessed that stable spawning occurred following the introduction to the Cheonggye stream.

• Journal of Wetlands Research
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• v.22 no.1
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• pp.31-38
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• 2020

Weirs are to secure amount water of streams and drop structures are to enhance stabilization of stream bed and bridges are to connect isolated region, which are called stream crossing structures. In the stream design criteria, directions for minimum size of structures are suggested to secure stability of stream crossing structures. However the sizes of almost all existing weirs and drop structures are not satisfied with the stream design criteria and only 22 percent of the peirs of bridges are satisfied. To enhance hydraulic stability of existing weirs and drop structures, it is required that the ratio of bed protection to apron should be above 3.3. According to factual survey of structures in the sample streams, it has been shown that the longitudinal slope of rapid works with 1:20 is the most reasonable to design velocity if existing weirs and drop structures are rehabilitated into rapid works. It has been known that violating freeboard and span length of piers should make existing bridges reconstructed or removed. However, comprehensive review including deterioration level of bridges, special regulation for span length, etc. should be considered to determine rehabilitation plan of bridges. In this study, a procedure has been suggested to improve hydraulic stability of weirs, drop structures and piers of bridges. Sound environment of stream and reduction of natural disaster could be achieved by improving stability of cross structures, which could be obtained by governmental budget and active stream management including observance of design criteria.