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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.
낙동·고령 중권역의 표층 퇴적물 입도 조성 및 유기물질 분포 특성 변화
김신 ( Shin Kim ),안정민 ( Jungmin Ahn ),김형근 ( Hyounggeun Kim ),권헌각 ( Heongak Kwon ),김경훈 ( Gyeonghoon Kim ),신동석 ( Dongseok Shin ),양득석 ( Deukseok Yang ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.6
To investigate the distribution characteristics of grain size and organic matter of surface sediments from the Nakdong-Goryeong Mid-watershed, surface sediments were collected and analyzed. The samples were collected from six sited at four different times between May 2013 and May 2014. The were analyzed for grain size, water content, ignition loss, chemical oxygen demand, total organic carbon and total nitrogen. The surface sediments were mainly composed of medium sand (mean 44.7%) and coarse sand (mean 32.8%) and became coarser in May 2014. Fine sediments at the site NG-2 were poorly sorted and positively skewed, and occur in a tributary environment that is relatively low-energy compared with the other sites. The water content at the studied sites (15.3 ~ 34.9%) averaged 20.25%, and ignition loss (0.4 ~ 5.8%) and total nitrogen (274 ~ 2493 mg/kg) averaged 1.33% and, 696 mg/kg, respectively. These values indicated that the sediments were not seriously contaminated when compared with the sediment pollution evaluation standard of the National Institute of Environmental Research. The chemical oxygen demand (mean 0.17%) was at the non-polluted level compared with United States Environmental Protection Agency sediment quality standards. The total organic carbon (mean 0.18%) at all sites except site NG-2 (lowest effect level) was the no effect level of the Ontario sediment quality guidelines. The COD/IL (0.02 ~ 0.20) and C/N (0.73 ~ 6.76) were less than 1 and 10, respectively. Organic matter in the study area produced naturally from aquatic organisms. Results of principal component analysis showed that fine sediments (very fine sand and silt) were significantly affected by organic matters (ignition loss, chemical oxygen demand, total organic carbon and total nitrogen). In addition, the highest organic matters content in the study area occurred at the site with the finest sediments (NG-2).
정승민(Seungmin Jeong),김형근(Hyounggeun Kim),황태경(Taekyung Hwang) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5
본 논문에서는 유한요소해석을 이용하여 복합재 연소관의 금속 보스에 대한 형상 최적설계기법을 제안하였다. 복합재 연소관의 구조 안정성을 위해 연소관 내압에 의한 돔 부위의 섬유응력과 보스체결볼트의 응력을 제한하였고, 경량화를 위해 보스의 무게를 목적함수로 설정하였다. 또한 반응표면법(Response Surface Method)을 이용하여 특성치에 대한 반응표면모델을 구축하였다. 그리고 분산분석을 이용해 각 특성치에 대한 설계변수의 유의성을 평가하고 회귀분석을 통해 구축된 모델의 적합성을 검증하였다. 최적화를 위해 순차이차계획법(Sequential Quadratic Programming) 알고리즘을 이용하였고, 도출된 최적형상에 대한 구조해석을 수행함으로써 제안한 기법의 효용성을 검증하였다. This paper proposes a shape optimization of the metal boss for a composite motor case using finite element analysis. For the structural safety and the weight reduction of the composite motor case, under the internal pressure, the fiber stress in the dome area and the tightening bolt stress are constrained and the boss weight is set to objective function, respectively. The response surface models are constructed for the performance characteristics by using response surface method. The significance of the design variables about the performance characteristics is evaluated through the ANOVA(Analysis of Variance) and the goodness of fit test for the constructed model is performed through the regression analysis. The SQP(Sequential Quadratic Programming) algorithm is used for the optimization and the proposed method is verified by performing structural analysis for the optimum shape.
정승민(Seungmin Jeong),김형근(Hyounggeun Kim),황태경(Taekyung Hwang) 한국추진공학회 2016 한국추진공학회지 Vol.20 No.6
This paper proposes a shape optimization of the metal boss for a composite motor case using finite element analysis. For the structural safety and the weight reduction of the composite motor case, under the internal pressure, the fiber stress in the dome area and the tightening bolt stress are constrained and the boss weight is set to objective function, respectively. The response surface models are constructed for the performance characteristics by using response surface method. The significance of the design variables about the performance characteristics is evaluated through the ANOVA(analysis of variance) and the goodness of fit test for the constructed model is performed through the regression analysis. The SQP(sequential quadratic programming) algorithm is used for the optimization and the proposed method is verified by performing structural analysis for the optimum shape.