• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.564-571
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• 2011

In order to establish fundamental data for stream restoration and environmental flow, we investigated fish fauna, community and physical habitat conditions in the Dal Stream of Han River Basin. Field monitoring including fish sampling was conducted from September 2008 to October 2009. A total number of fish caught in the 5 sites was 2,080 representing 9 families 35 species, and 19 species (54.3%) including Acheilognathus koreensis and Iksookimia koreensis were Korean endemic species during the study period. The most frequently found species in number was pale chub (Zacco platypus, 25.7%, n = 632) followed by Coreoleuciscus splendidus (18.0%, n = 375) and Z. koreanus (13.0%, n = 272). The lower reach of Dal Stream was more abundance of species, high diversity, evenness and richness, and lower dominance index than those of the upper reach. According to the dendrogram established at 0.63 level of similarity rate, sampling stations were divided into 2 groups. Most of upper streams in Korea consist of riffles and runs that are repeatedly followed by another one. However, stream channelization and leveling have caused reduction of habitat diversity. Therefore, it is necessary to make an effort on stream rehabilitation with evaluation of physical habitat condition by indicator species in order to maintain biodiversity and perform ecological restoration.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.63-73
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• 2020

Drought is considered as a devastating hazard that causes serious agricultural, ecological and socio-economic impacts worldwide. Fundamentally, the drought can be defined as temporarily different levels of inadequate precipitation, soil moisture, and water supply relative to the long-term average conditions. From no unified definition of droughts, droughts have been divided into different severity level, i.e., moderate drought, severe drought, extreme drought and exceptional drought. The drought severity classification defined the ranges for each indicator for each dryness level. Because the ranges of the various indicators often don't coincide, the final drought category tends to be based on what the majority of the indicators show and on local observations. Evaporative Stress Index (ESI), a satellite-based drought index using the ratio of potential and actual evaporation, is being used as a index of the droughts occurring rapidly in a short period of time from studies showing a more sensitive and fast response to drought compared to Standardized Precipitation Index (SPI), and Palmer Drought Severity Index (PDSI). However, ESI is difficult to provide an objective drought assessment because it does not have clear drought severity classification criteria. In this study, U.S. Drought Monitor (USDM), the standard for drought determination used in the United States, was applied to ESI, and the Percentile method was used to classify drought categories by severity. Regarding the actual 2017 drought event in South Korea, we compare the spatial distribution of drought area and understand the USDM-based ESI by comparing the results of Standardized Groundwater level Index (SGI) and drought impact information. These results demonstrated that the USDM-based ESI could be an effective tool to provide objective drought conditions to inform management decisions for drought policy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.158-166
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• 2018

Contrary to urban development, urban regeneration is a process of land development through conservation, restoration, and management. In particular, ecologically based urban regeneration is an attempt to improve the quality of life in an area, establish a stable settlement space, and revitalize the local economy by considering the ecological environment. In this regard, the objectives of this study were to establish theoretical concepts and analyze the successful foreign cases of ecologically based urban regeneration, and propose a direction of socio-economic regeneration along with the physical-environmental regeneration of urban areas in Korea. The study results suggest the following. First, strategies must be developed to coordinate public transportation, such as buses and subways, by considering the importance of bicycle riders, along with the sustainable-commuting system. Second, both the importance of planning parks and trails around water systems in various scales while maintaining the existing natural environment as well as using natural elements, such as electric vehicles and wind-power generation systems, were emphasized. Third, urban regeneration for increased energy efficiency requires specific architectural planning and facilities. Fourth, education and research for easy access by the public, as well as public-private partnership, will be needed in the regeneration process.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.686-694
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• 2019

This study was carried out to identify the long-term changes to beech forest due to climate change in Ulleung-do. To study the traits of the stand structure of beech forest with micro-topography, we investigated the distribution of the basal area, important values, and indicated species in a small ridge between Albong basin and Seongin-bong peak, and 1-ha stands (20 m × 20 m, 25 sites) dominated beech species including on the upper slope and valley parts. The result showed that the indicator species characterizing the vegetation communities were Tsuga sieboldii, Rhododendron brachycarpum, and Mitchella undulata in the small ridge and Celtis jessoensis, Dryopteris crassirhizoma, and Ulmus laciniata in the valley part. Moreover, the individuals with the total DBH < 10 cm were more predominant in the small ridge and upper slope than in the valley part, the individuals with DBH = 10-25 cm were predominant in the small slope, and individuals with DBH = 25-45 cm and DBH > 45 cm were predominant in the upper slope. The reason for the predominant distribution of beech stand with DBH<10 cm in all terrains is suggested to be germination by nutritional propagation rather than secondary succession caused by artificial disturbances and seed propagation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.101-109
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• 1997

The present study was carried out to investigate the temporal and spatial changes in species composition and abundance of polychaetes in Lake Shihwa. Macrobenthic fauna were collected from eight sampling surveys performed in March, June, September and December of 1994, March and October of 1995, February and August of 1996, using a modified van Veen grab with 0.1 $m^2$ coverage area. Polychaete worms, the most abundant macrofaunal group, comprised of 1~22 species at each investigation; number of species continuously decreased during the survey period. The mean density of polychaete was $794{\pm}1,275\;indiv.{\cdot}m^{-2}$ and showed a large fluctuation over time. The variation in abundance was mainly coupled with the domination of Polydora ligni occupying 83% in total density. The next dominant species were Pseudopolydora kempi (mean density of 31 $indiv.{\cdot}m^{-2}$) and Capitella capitata (mean density of 23 $indiv.{\cdot}m^{-2}$). Abundant polychaetes in Lake Shihwa are known to be tolerant to sediment pollution. Ecological indices such as diversity (H') and dominance (D) also indicated that the number of species significantly decreased and a few species predominated in Lake Shihwa after the dike construction. The azoic zone were extended from the upper reach of Lake Shihwa to the vicinity of the dike over time. The reduced number of species, predominance of pollution indicator species and development of an azoic zone reflect severe deterioration of benthic environments in Lake Shihwa.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.20-26
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• 2016

The residence time measures the time spent by a water parcel or a pollutant in a given water body. So residence time of water is widely used as an indicator of how a substance will remain in an estuary and it is used to enable comparisons among different water bodies. To estimate residence time of particulate matters from land and aquaculture, EFDC that includes particle tracking model was applied to the Geoje Bay. Modelled average residence time was about 65 days in the inner part. It meant it takes about 2 months for substance from land and aquaculture to be transported to the outside of Geoje Bay. The results indicated that residence time varied spatially throughout Geoje Bay depending on tidal flushing and, in general conditions, tidal flushing exerts the greatest influence to the flushing of Geoje Bay. This reveals relationships between residence times of particulate matters and physical properties of the bay and Geoje Bay is vulnerable to water quality problem.

• Journal of Environmental Impact Assessment
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• v.22 no.6
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• pp.591-607
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• 2013

The objectives of the study were to evaluate the aquatic environment of an urban stream using various ecological parameters of biological biomarkers, physical habitat quality and chemical water quality and to develop a "Multimetric Eco-Model" ($M_m$-E Model) for the ecosystem evaluations. For the applications of the $M_m$-E model, three zones including the control zone ($C_Z$) of headwaters, transition zone ($T_Z$) of mid-stream and the impacted zone ($I_Z$) of downstream were designated and analyzed the seasonal variations of the model values. The biomarkers of DNA, based on the comet assay approach of single-cell gel electrophoresis (SCGE), were analyzed using the blood samples of Zacco platypus as a target species, and the parameters were used tail moment, tail DNA(%) and tail length (${\mu}m$) in the bioassay. The damages of DNA were evident in the impacted zone, but not in the control zone. The condition factor ($C_F$) as key indicators of the population evaluation indicator was analyzed along with the weight-length relation and individual abnormality. The four metrics of Qualitative Habitat Evaluation Index (QHEI) were added for the evaluations of physical habitat. In addition, the parameters of chemical water quality were used as eutrophic indicators of nitrogen (N) and phosphorus (P), chemical oxygen demand (COD) and conductivity. Overall, our results suggested that attributes of biomarkers and bioindicators in the impacted zone ($I_Z$) had sensitive response largely to the chemical stress (eutrophic indicators) and also partially to physical habitat quality, compared to the those in the control zone.

• 한국해양학회지
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• v.21 no.3
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• pp.156-170
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• 1986

The phytoplankton ecology of estuarine waters was investigated in the Kyeonggi Bay from May 1981 to September 1982 on monthly basis. In this study area, a total of 228 phytoplankton species was identified. Among these taxa, the most dominant species are diatoms in this area. Tychopelagic plankton occupies 40.4% of total species. The percentage of tychopelagic plankton density ranged from 10.2% in September to 92.7% in March of monthly standing crops. From late autumn to early spring, the percentage values are more than 72%. They play an important role from late autumn to early spring in this estuarine plandton community. These tychopelagic planktons are induced from benthic diatoms. Because the bottom shear stresses generated by the tides and winds are stronger than the adhesive and tractive force of benthic diatoms, most of benthic diatoms must be resuspended into tychopelagic suspensions during autumn and winter. Paralia sulcata is the most important tychopelagic plankton as an indicator species of water mixing in the eastern coastal area of Yellow Sea. This species seems to have even broader tolerance to the environmental stress than Skeletonema costalum, and tends to fill the gaps in winter, when the phytoplandton is relatively unsuccessful. Skeletonema costatum and Chaetoceros debilis are dominant in other seasons. Typical blooms of phytoplankton occur in spring and early autumn, The first bloom is started by Skeletonema costatum in early May, second peak is formed by various diatom population in September.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.262-269
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• 1994

In order to determine ecological niches of forests in Mt. ManDeok, the studies were analyzed on the methods of TWINSPAN and DCCA ordination. The results are summarized as follows ; Four groups were determined by TWINSPAN : Styrax japonica. Quercus variabilis-Quercus mongolica, Carpinus laxiflora and Fraxinus mandshurica-Cornus controversa communities. In the relations of community structures and environmental factors, Styrax japonica community were distributed in the rich site of magnesium and organic matter, Quercus variabilis-Quercus mongolica community in the low potassium, Carpinus laxiflora community in the low available phosphorus, and the factors in influencing community distribution were elevation. The importance value of Quercus variabilis recorded the highest in all the quadrats sampled and the next values then came those Cornus controversa. Quercus variabilis, Lindera erythrocarpa. Quercus mongolica, Fraxinus mandshurica. Cornus controversa, Symplocos chinensis for pilosa, Acer mono, Carpinus laxiflora, and Styrax japonica in the orders. The species diversities of major dominant species recorded the highest value in the communities of Quercus variabilis-Quercus mongolica but they lowest value in the communities of Fraxinus mandshurica-Cornus controversa.

• Korean journal of applied entomology
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• v.46 no.3
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• pp.335-341
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• 2007

The main habitats of diving beetles in agricultural ecosystems were identified as ponds, irrigation channels, and reservoirs, where the water system is maintained throughout the year. Four species, Cybister japonicus, Cybister brevis, Hyphydrus japonicus and Noterus angustulus, were selected as biological indicators which can be used to evaluate the healthiness of the agricultural ecosystem. The species number of 4 indicator species, the species number of diving beetle species, and the diversity index were used as factors for environmental evaluation. The evaluation was classified into grades $I{\sim}IV$. The non-fertilizer and non-pesticide agricultural practicing area and the sustainable agricultural practicing area were evaluated as grades $I{\sim}II$, and the general agricultural area to be relatively fine with a grade II. However, the analysis indicated the agricultural areas near a residential area and an industrial complex to be poor with a grade of IV, suggesting that immediate improvement in the agricultural environment is needed.