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낙동강 본류에 분포하는 표층 퇴적물의 지화학적 특성 변화
김신 ( Shin Kim ),이권철 ( Kwonchul Lee ),김주언 ( Jueon Kim ),정강영 ( Kangyoung Jung ),안정민 ( Jungmin Ahn ),김형근 ( Hyounggeun Kim ),이인정 ( Injung Lee ),신동석 ( Dongseok Shin ),양득석 ( Deukseok Yang ) 한국환경과학회 2017 한국환경과학회지 Vol.26 No.3
To certificate change in the geochemical characteristics of surface sediments in the main stream of the Nakdong River, surface sediments from 12 sampling sites during the first and second half year (total 24 sampling sites) were collected and analyzed for grain size, ignition loss, total organic carbon and heavy metal content. Surface sediments mainly composed of sand (coarse and medium sand) and fining changed from the first half to the second half of the year. Ignition loss, total organic carbon and heavy metals content increased in the second half of the year. Some heavy metals (Zn, Ni and Cu) were found to be at the lowest effect levels according to Ontario sediment quality guidelines. Additionally, most heavy metals were found to be at the non polluted level and level I according to USEPA sediment quality standards and National Institute of Environmental Research sediment pollution evaluation standard, respectively. The enrichment factor (< 1) and index of geoaccmulation (< 0) were non polluted in the study area. The correlation analysis results showed that ignition loss, total organic carbon and heavy metal content were highly correlated with grain size. Regarding changes in geochemical characteristics of surface sediments in the study area, grain size fine and organic matter and heavy metal content increased in the second half year. Nonetheless these results indicated pollution levels that did not adversely affect the benthos.
김신 ( Shin Kim ),김주언 ( Jueon Kim ),이권철 ( Kwonchul Lee ),이규열 ( Kyuyeol Lee ),전혜린 ( Hyelyn Jeon ),유재정 ( Jaejung Yu ),이인정 ( Injung Lee ),안정민 ( Jungmin Ahn ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.8
In order to certificate the distribution and pollution of heavy metal of surface sediments in Nakdong River were collected and analyzed for grain size, water content, ignition loss and heavy metal content. Surface sediments mainly composed of sand(avg. 94.6%) and water content and ignition loss were 20.46%, 1.53% on average. Grain size were relatively fine and organic matter content were relatively high in the Hoichun and Sunakdonggang. Most of heavy metal content(Zn > Cr > Pb > Ni > Cu > Hg) in the Deokcheongang and Sunakdonggang were higher than the other streams. The Igeo were non polluted(less than 0) in all streams and the EF were relatively high in the small stream and PLI were non polluted(less than 1). In addition, organic matter, heavy metal content and pollution were highly correlation with grain size. Surface sediments in study area, heavy metal pollution of the Sunakdonggang were relatively high compared to the other stream but these results were not serious pollution that exceed the sediment pollution evaluation standard of river and lake in Korea and pollution levels adversely affected the majority of benthos were not.
예비압입에 의한 Al 5052-H18의 피로균열 지연특성 연구
황정선(Jungsun Hwang),조환기(Hwankee Cho),김주언(Jueon Kim) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.1
본 논문은 Al 5052-H18 판재에서 피로균열성장을 지연시키기 위한 방법으로써 예비압입의 적용 기법과 균열성장지연 효과에 관하여 기술하였다. 시편은 두께가 일정한 한쪽 모서리 균열이 있는 시편을 사용하였으며, 균열성장률이 최소가 되는 압입력을 찾아내기 위해서 압입력을 변화시키면서 피로시험을 수행하였다. 시험결과로부터 압입력의 크기에 따라 균열지연효과가 달라지며, 예비압입에 의한 균열성장지연 거동 특성이 효과적으로 나타남을 확인하였다. 균열지연 거동형태는 압입력의 크기에 무관하게 일정한 메커니즘을 보여주었으며 이로부터 예비압입시 균열성장거동 특성에 대한 정성적 모델을 도출하였다. This paper described the retardation effect of fatigue crack growth and application technique of pre-indentation to decelerate the crack propagation rate in the thin sheet of 5052-H18 aluminum alloys. The test specimen with a single-sided edge crack was used. A series of fracture test was conducted to determine the optimum indentation force showing the maximum retardation effect. Test results indicate that crack retardation effect depends on the level of indentation force and the pre-indentation contributes effectively for crack growth retardation. The typical model of crack growth retardation mechanism by pre-indentation is derived from the fact that the behaviors of crack growth retardation show similar mechanism to each indentation force.
후류와 타워의 영향을 고려한 수평축 풍력발전기 블레이드의 비정상 하중 예측을 위한 새로운 자유후류기법의 연구
신형기(Shin, Hyungki),박지웅(Park, Jiwoong),이수갑(Lee, Soongab),김주언(Kim, Jueon) 한국신재생에너지학회 2005 신재생에너지 Vol.1 No.1
A critical issue in the field of the rotor aerodynamics is the treatment of the wake. The wake is of primary importance in determining overall aerodynamic behavior, especially, a wind turbine blade includes the unsteady airloads problem. In this study, the wake generated by blades are depicted by a free wake model to analyse unsteady loading on blade and a new free wake model named Finite Vortex Element(FVE hereafter) is devised in order to include a wake-tower interaction. In this new free wake model, blade-wake-tower interaction is described by cutting a vortex filament when the filament collides with a tower. This FVE model is compared with a conventional free wake model and verified by a comparison with NRELand SNU wind tunnel model. A comparison with NREL and SNU data shows validity and effectiveness of devised FVE free wake model and an efficient.