• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.2
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• pp.77-83
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• 2012

Numerical analyses through Computational Fluid Dynamics have been performed to investigate the seawater flow field characteristics for various shrouds used in horizontal axis tidal current turbine systems. Seawater flow characteristics are largely influenced under constant tidal current velocity by the shroud geometry and there is considerable difference in fluid velocity distributions around the shrouds. Especially the location and magnitude of maximum seawater flow velocity directly affect turbine performance for power generation. For the cylinder-diffuser type shroud system whose cylinder and diffuser parts have the same length accelerated flow region is formed in the overall cylinder part while maximum velocity in the nozzle-diffuser type whose nozzle and diffuser parts have the same length with symmetry, locally appears near the minimum sectional area. In case of cylinder-diffuser type shroud fluid velocity increases rather high compared with current velocity. And fluid velocity at the centerline gradually increases from the entrance, and then decreases rapidly after reaching a peak close to the middle of the cylinder part unlike the nozzle-diffuser while there is not much variation near the rear of the shroud. These results of the seawater flow characteristics with various shroud geometries can be applied to optimal design for the development of efficient tidal current power generation systems.

• Journal of Environmental Impact Assessment
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• v.30 no.3
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• pp.164-174
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• 2021

Information on biodiversity plays an important role in conservation planning for ecosystem. As existing biodiversity indices are calculated and predicted only based on the number of individuals and species, it is difficult to explain aspects of genetic and ecological diversity. Phylogenetic diversity can indirectly evaluate ecological diversity as well as genetic diversity overlooked by existing biodiversity assessments. In this study, typical metrics of biodiversity (e.g., species diversity, species richness, etc.) and phylogenetic diversity were evaluated together using a long-term monitoring data of winter birds in Jungrang, Cheonggye and Anyang stream where are designated as Seoul migratory bird reserves. Then discussed the meaning of each assessmentresult. In Jungrang and Anyang stream, the number of individuals generally decreased overtime, whereas in Cheonggye stream, there was no significant change. In addition, species abundance increased over time slightly in Cheonggye stream, while there was no significant change in Jungrang and Anyang stream. Species diversity temporally increased in Jungrang and Cheonggye stream, excluding Anyang stream, but phylogenetic diversity showed a tendency to increase only in Cheonggye stream. These changes in the biodiversity assessment indices are thought to be due to anthropogenic disturbances such as construction that occurred within each site, and it was shown that species diversity and phylogenetic diversity do not always lead to the same assessment results. Therefore, this study suggests that biodiversity assessment needs to be considered from various contexts such as genetic and ecological perspectives.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1999.04a
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• pp.316-318
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• 1999

• The Microorganisms and Industry
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• v.26 no.2
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• pp.32-40
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• 2000

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.154.2-155
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• 1997

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.133.4-133
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• 2003

• Journal of Environmental Impact Assessment
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• v.23 no.5
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• pp.406-416
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• 2014

When abnormal taste and odor were detected in the tap water of the North-Han river watershed during the dry season in late 2011, excessive nutrients with algal growth in the Lake Uiam and weather factors were considered to be among its causes. The nutrients, in particular, originated from domestic sewage in the Chuncheon area. This study was conducted to investigate relations between the algal growth in the Lake Uiam and the contribution of nutrients from public sewage treatment works (PSTWs) in Chuncheon city, and based on this to analyze the environmental impact. Nutrients in the Lake Uiam have already been accumulated to the level of eutrophication. Even in winter, the conditions in the lake such as retention time and water temperature were favorable to boost algal growth. After phosphorus treatment processes were introduced, the PSTWs in the Lake Uiam watershed were able to reduce the total phosphorus loads by 43%. The algal concentrations in the Lake Uiam also dropped by about 7%. The nitrogen treatment efficiencies in the PSTWs, on the other hand, remained almost the same after the introduction of the phosphorus treatment processes. To solve these problems more efficiently, it is necessary to develop management strategies for the upstream area of the Lake Uiam and set plans to improve nitrogen treatment operation and management for the PSTWs in Chuncheon.

• Korean Journal of Environment and Ecology
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• v.23 no.4
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• pp.317-325
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• 2009

This study was presented to effect of prescribed burning to the avian fauna and was conducted from March to October 2007 in Sihwa grassland, Gyeonggi-do, Korea. Prescribed burning was conducted at Sihwa grassland of Songjeong-ri Mado-myeon, Hwaseong city from 28th February to 1 st March 2007. Thirty birds species were observed and sum of the maximum count was 181 individuals at the prescribed burning area for all survey time. Observed species was 24 species and sum of the maximum count was 154 individuals on the unburned area. Number of species and sum of the maximum count at the prescribed burning area was greater than unburned area. There is no differences in the dominant species between prescribed and unburned area. Average number of species, number of individuals, species diversity and species richness of the prescribed burning area were greater than unburned area in early stage (from March to June) after prescribed burning. Community indices in burned area during early season were different with unburned area by prediscribed burning. However, the indices had became similar between burned and unburned area as time goes by. Disturbance by prescribed burning created new habitat and feeding site temporarily for the avian species in grassland. We would suggest that prescribed burning is most effective method to maintain grassland ecosystem from the invading bush or tree and periodical prescribed burning is a good method to preserve and manage the grassland ecosystem.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.10a
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• pp.23-26
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• 2003

정치망은 어군의 자연적인 이동 경로를 길그물로써 차단하여 어군을 운동장으로 유도한 후, 비탈그물을 통해 원통으로 들어가게 하여 어획하는 소극적 어구이다. 정치망이 수중에 형성하고 있는 공간의 규모와 형태는 해면에 떠있는 뜸의 형상 및 각 부분의 부설 깊이와 침강 수심을 조사하여 추정하고 있으나, 정치망이 설치된 해역의 조류 방향과 유속에 따라 수중 형상의 크기나 형태가 변형되어 어획량에 영향을 주는 요인이 될 뿐만 아니라 강한조류나 악천후에 의한 파손 등으로 조업 손실을 초래하기도 한다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.236-237
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• 2002

해초생태계는 해초 잎 및 지하경, 그리고 뿌리등 해초와 직간접적으로 영향을 주고 받을 수 있는 여러 생물들: 조류와 무척추동물, 해초지를 산란장이나 생육장으로 삼고 있는 어류, 그리고, 식물 및 동물 플랑크톤 등으로 구성되어 있다. 이 중 부착조류는 해초생태계 내에서 생산성의 가장 중요한 요소일 뿐만이 아니라, 종 다양성을 증가시키며, 무척추동물의 먹이 공급의 기본적 요소이다 (McRoy and Helfferich, 1977; Coleman and Burkholder, 1995). (중략)