댐 저수지의 퇴사위 결정 방법에 관한 연구

주홍준,김형수,조운기,곽재원 한국수자원학회 2018 한국수자원학회논문집 Vol.51 No.1

This study examined how to determine the optimal sediment level in dam reservoir for efficient plan and operation of dam. Currently, Korea is applying a horizontally accumulated method for sediment level estimation for the safety design of dam and so the method estimated relatively higher level than others. However, the sediment level of dam reservoir should be accurately estimated because it is an important factor in assessing life cycle of a dam. The sediment level in dam reservoir can be determined by SED-2D model linked with RMA-2, horizontally accumulated method, area increment method, and empirical area reduction method. The estimated sediment level from each method was compared with the observed sediment level measured in 2007 in Imha dam reservoir, Korea and then the optimal method was determined. Also, the future sediment level was predicted by each method for the future trend analysis of sediment level. As the results, the most accurate sediment level was estimated by the empirical area reduction method and the future trend of sediment level variation followed the past trend. Therefore, we have found that the empirical area reduction method is a proper one for more accurate estimation of sediment level and it can be validated by the results from a numerical model of SED-2D linked with RMA-2 model. 본 연구에서는 댐의 효율적인 계획 및 운영을 위해 댐 저수지의 최적 퇴사위 결정 방법에 대해 고찰하였다. 현재 우리나라는 안전한 설계에 의거하여 댐 저수지 사수위 내의 퇴사위 결정 방법은 비교적 높게 산정되는 수평퇴사법을 주로 적용하고 있지만, 댐 저수지의 퇴사위는 정확하게 계획되어야 하며, 이는 댐 생애주기 평가 차원에서도 중요한 요소이다. 댐 저수지의 퇴사위 결정을 위해 대표적인 방법으로는 RMA-2와 연계된 SED-2D의 모형에 의한 방법, 수평퇴사법, 면적증분법(area increment method), 경험적면적감소법(empirical area reduction method)이 있다. 본 연구에서는 최적 퇴사위 결정을 위해 이를 산정하여 2007년 기준 실측 퇴사위와 비교하였다. 또한, 현재 및 미래 퇴사위를 예측하여 각 방법별로 경향과 추이를 분석하였다. 실측 퇴사위와 산정된 퇴사위를 비교한 결과, 경험적면적감소법이 실측값과 가장 근사하게 산정된 것을 확인할 수 있었으며, 현재 및 미래의 퇴사위는 전반적으로 과거 퇴사위의 경향과 추이를 따라가는 것으로 확인되었다. 따라서, 본 연구의 결과를 토대로 보면 경험적면적감소법의 이용이 적절할 것으로 판단되고, 모형에 의해 분석 결과의 타당성을 검정하는 것이 합리적이라 생각된다.

Comparative analysis of methods for sediment level estimation in dam reservoir

Joo, Hong Jun,Kim, Hung Soo,Cho, Woon ki,Kwak Jae won 한국수자원학회 2018 한국수자원학회논문집 Vol.51 No.1

본 연구에서는 댐의 효율적인 계획 및 운영을 위해 댐 저수지의 최적 퇴사위 결정 방법에 대해 고찰하였다. 현재 우리나라는 안전한 설계에 의거하여 댐 저수지 사수위 내의 퇴사위 결정 방법은 비교적 높게 산정되는 수평퇴사법을 주로 적용하고 있지만, 댐 저수지의 퇴사위는 정확하게 계획되어야 하며, 이는 댐 생애주기 평가 차원에서도 중요한 요소이다. 댐 저수지의 퇴사위 결정을 위해 대표적인 방법으로는 RMA-2와 연계된 SED-2D의 모형에 의한 방법, 수평퇴사법, 면적증분법(area increment method), 경험적면적감소법(empirical area reduction method)이 있다. 본 연구에서는 최적 퇴사위 결정을 위해 이를 산정하여 2007년 기준 실측 퇴사위와 비교하였다. 또한, 현재 및 미래 퇴사위를 예측하여 각 방법별로 경향과 추이를 분석하였다. 실측 퇴사위와 산정된 퇴사위를 비교한 결과, 경험적면적감소법이 실측값과 가장 근사하게 산정된 것을 확인할 수 있었으며, 현재 및 미래의 퇴사위는 전반적으로 과거 퇴사위의 경향과 추이를 따라가는 것으로 확인되었다. 따라서, 본 연구의 결과를 토대로 보면 경험적면적감소법의 이용이 적절할 것으로 판단되고, 모형에 의해 분석 결과의 타당성을 검정하는 것이 합리적이라 생각된다. This study examined how to determine the optimal sediment level in dam reservoir for efficient plan and operation of dam. Currently, Korea is applying a horizontally accumulated method for sediment level estimation for the safety design of dam and so the method estimated relatively higher level than others. However, the sediment level of dam reservoir should be accurately estimated because it is an important factor in assessing life cycle of a dam. The sediment level in dam reservoir can be determined by SED-2D model linked with RMA-2, horizontally accumulated method, area increment method, and empirical area reduction method. The estimated sediment level from each method was compared with the observed sediment level measured in 2007 in Imha dam reservoir, Korea and then the optimal method was determined. Also, the future sediment level was predicted by each method for the future trend analysis of sediment level. As the results, the most accurate sediment level was estimated by the empirical area reduction method and the future trend of sediment level variation followed the past trend. Therefore, we have found that the empirical area reduction method is a proper one for more accurate estimation of sediment level and it can be validated by the results from a numerical model of SED-2D linked with RMA-2 model.

Current Status of Erythrocyte Sedimentation Rate Test and Results According to Methods in Korea

Kibum Jeon,Young Min Kim,Young Kyung Lee 대한임상검사정도관리협회 2022 Journal of Laboratory Medicine And Quality Assuran Vol.44 No.3

Background: The erythrocyte sedimentation rate (ESR) test is one of the most frequently performed in clinical laboratories. In addition to traditional ESR methods such as the Westergren and Wintrobe methods, these methods have been diversified in recent years. We investigated the current status of ESR methods in Korea and the distribution of ESR results according to the methods based on the external quality assessment (EQA) data of the Korean Association of External Quality Assessment Service. Methods: Data from the ESR EQA, conducted twice a year from 2018 to 2021, were collected. We investigated the ESR methods, equipment usage status, and ESR results according to the methods. We also analyzed trends in proficiency test results by year. Results: The alternate method was the most frequently used ESR method in Korea (56.0%). The distribution of interlaboratory coefficients of variation (CVs) was 21.4%±14.3% (mean±standard deviation) for the Wintrobe method, 33.4%±12.8% for the Westergren method, and 22.8%±19.7% for the modified Westergren method, with no statistically significant difference between the three methods. The interlaboratory CVs of the alternate method were significantly lower than those of all other methods (6.2%±2.2%, P <0.001). The interlaboratory CVs showed a tendency to gradually decrease by year for all methods. Conclusions: Automated ESR methods are used in most laboratories in Korea. The interlaboratory CVs were lowest for the alternate method and tended to decrease as EQA was implemented. The ESR EQA is expected to improve the quality of the ESR.

Research on characterization method and influencing factors of sedimentation stability of magnetorheological fluid

Yuqing Li,YiPing Luo,Ying Wang,Jiao Luo,Yameng Chen 한국유변학회 2021 Korea-Australia rheology journal Vol.33 No.4

The sedimentation stability of Magnetorheological fluid (MRF) is one of the research hotspots in the academic field of magnetorheological science. Excellent sedimentation stability is of great significance for the preservation and application of MRF. Given many traditional methods of characterization of sedimentation stability, this paper proposes a new method to characterize the sedimentation stability of MRF based on the change of shear yield stress during the sedimentation process of MRF. Then, the key components of the selfmade MRF shear yield stress test device were introduced in detail, and three different surfactants containing dodecyl benzoate, polyethylene glycol and oleic acid were prepared. And then used the device to test their effects on the sedimentation stability of MRF. The results showed that oleic acid has the best effect on improving the sedimentation stability. Finally, the change law of shear yield stress of MRF in the next 90 days was predicted successfully by fitting experimental data based on the least square method. By comparing the test value and fitting value of 60-75 days, the error of the best fitting result were within 3%, this showed the reliability of the predicted results.

전산유체역학을 이용한 응집지 유입 분배수로의 유량 균등배분에 관한 연구

박진영 ( Chinyoung Park ),전용성 ( Yongseong Jeon ),하현섭 ( Hyunsup Ha ),황태문 ( Tae-mun Hwang ),조정훈 ( Jeonghoon Cho ) 한국수처리학회(구 한국수처리기술연구회) 2018 한국수처리학회지 Vol.26 No.5

The water should be evenly distributed to each flocculation/sedimentation basin because it can affect the floc formation and the efficiency of sedimentation. In order to find the optimum operation method for the equal distribution of the flow rate by using the CFD (Water-CFD), the flow analysis was carried out by considering the basic operation condition and improvement plans. From the results of the CFD simulation, the following conclusions were obtained. When 8 all flocculation/sedimentation basins were operated, the influx of the outermost 1st and 8th flocculation/sedimentation basins were the largest but the amount of 4th and 5th flocculation/sedimentation basins which were located at the center of the distribution channel were the least. The operation rate of water purification plant was 40% compared to facility capacity, therefore it was considered to stop the flocculation/sedimentation basins. The optimum operation method to minimize the influent flow difference was the stopping the 4th and 5th flocculation/sedimentation basins located at the center. The other methods such as the extension of the distribution channel(waterway) and the installation of the disturbance plate near the inlet of flocculation basin need the civil engineering work and the lots of extra costs. However, the effect of the equal distribution is not greater than the change of operation method.

A discrete element model for the influence of surfactants on sedimentation characteristics of magnetorheological fluids

손권중 한국유변학회 2018 Korea-Australia rheology journal Vol.30 No.1

Hindering particle agglomeration and re-dispersion processes, gravitational sedimentation of suspended particles in magnetorheological (MR) fluids causes inferior performance and controllability of MR fluids in response to a user-specified magnetic field. Thus, suspension stability is one of the principal factors to be considered in synthesizing MR fluids. However, only a few computational studies have been reported so far on the sedimentation characteristics of suspended particles under gravity. In this paper, the settling dynamics of paramagnetic particles suspended in MR fluids was investigated via discrete element method (DEM) simulations. This work focuses particularly on developing accurate fluid-particle and particle-particle interaction models which can account for the influence of stabilizing surfactants on the MR fluid sedimentation. Effect of the stabilizing surfactants on interparticle interactions was incorporated into the derivation of a reliable contact-impact model for DEM computation. Also, the influence of the stabilizing additives on fluid-particle interactions was considered by incorporating Stokes drag with shape and wall correction factors into DEM formulation. The results of simulations performed for model validation purposes showed a good agreement with the published sedimentation measurement data in terms of an initial sedimentation velocity and a final sedimentation ratio.

토석류 유동층에서 토사체적 농도 특성에 관한 연구

김성덕(Sungduk Kim) 한국지반환경공학회 2014 한국지반환경공학회논문집 Vol.15 No.12

본 연구의 목적은 산지에서 세립사가 포함된 유동체 혼합물이 다양한 경사 각도를 갖는 수로에서 공급유량의 변화에 따른 토사체적농도를 분석한 것이다. 수치모델은 질량보존 및 운동량 보존에 관한 방정식 그리고 세립토와 조립토 방정식에 기초하여 유한차분법을 이용하여 수행되었다. 비탈 경사면 각도 변화에 따른 토사농도 비교에서 경사가 급할수록 토사체적 농도의 급격한 변곡점이 나타났다. 공급유량의 변화에서는 공급유량이 많을수록 Fluctuation이 발생하였고, 토석류의 상태가 난류형으로 변하여 토사가 부유사 형태로 변화되었다. 이는 토석류의 이동속도가 빠르게 됨을 알 수 있다. 포화된 조립토의 변화에 따른 비교에서는 그 길이가 길수록 고농도가 발생하였으므로 사면 안정을 위해서는 사면에서의 침식 가능 여부를 먼저 판단해야 된다. 본 연구의 결과는 강우 변화에 따른 비탈면 하류단에서의 유동체 혼합물의 토석류에 의한 재해를 예측 및 다양한 경사의 비탈면을 갖는 산지 밑에서의 토석류에 의한 재해에 대한 정보를 제공할 것이다. 또한 사면 안정 시 효율적인 사면 경사각도로 설치하는 것과 사면에서의 침식 방지 등에 있어 토석류와의 관계성 분석 및 토석류 재해를 막기 위한 다양한 대책을 세우는 데 효과적인 정보를 제공할 것이다. The purpose of this study is to estimate the sediment volume concentration of the liquified-solid mixture which is included fine sediment fractions, according to the variance of the channel slope and the water supply. The numerical model was performed by using the Finite Differential Element Method (FDM) based on the equation for the mass conservation, momentum conservation and the equation of coarse sediment an fine sediment. In comparison of varying the channel slope, the deeper the channel slope, the inflection point of the sediment concentration was occurred rapidly. In comparison of variance of the water supply, as the water supply increases fluctuation with high sediment concentration. In this situation, debris flow changes to the turbulent flow and the sediment becomes to be floated. In comparison varying the length paved saturated sediment, the longer the length, the high concentration of sediment occurred, for the safety of the slope it is needed to check the possibility of the erosion in the slope by debris flow. The results of this study will provide useful information in predicting of the disaster by the liquified-solid mixture and in prevention of the debris flow with various the slope in the mountain side.

잘피(Zostera marina)서식지 복원을 위한 최적 이식방법 및 시기 선정에 관한 연구

박정임,김영균,박상률,김종협,김영상,김정배,이필용,강창근,이근섭,Park, Jung-Im,Kim, Young-Kyun,Park, Sang-Rul,Kim, Jong-Hyeob,Kim, Young-Sang,Kim, Jeong-Bae,Lee, Pil-Yong,Kang, Chang-Keun,Lee, Kun-Seop 한국조류학회(藻類) 2005 ALGAE Vol.20 No.4

Seagrass bed is an important component in coastal and estuarine ecosystems, providing food and shelter to a wide variety of fauna. Recently, seagrass coverage has declined significantly due to anthropogenic influences such as reclamation, dredging, and eutrophication and consequently, necessity of seagrass habitat restoration is rising. Transplantation experiments with Zostera marina using TERFS, staple method, and shell method have been conducted at Dadae Bay, Kosung Bay and Jindong Bay on the south coast of Korea to select an optimal transplanting method for restoration of Z. marina habitat. Three experimental sites located at the vicinity of natural Z. marina beds with an average water depth of about 4m. Z. marina plants, which were collected from donor bed in Koje Bay were also transplanted at 7 different time from October 2003 to July 2004 to find appropriate transplanting time. Density of Z. marina was monitored monthly at both transplanted areas and natural beds. Transplantation using the staple method showed the highest survival rate of transplant. Shell method was also an effective transplanting method at muddy areas in Kosung Bay and Jindong Bay, but not suitable at sandy areas in Dadae Bay. These results suggest that sediment composition of transplanting areas should be considered for the selection of the optimal transplanting method. Z. marina transplanted during fall usually showed the highest survival rate, while most Z. marina plants transplanted in summer died due to high lethal temperature during this period.

Identification of a High-yield Technique for Isolating Endometrial Epithelial Cells from the Mouse Uterus : A Comparison of Mechanical and Sedimentation-adherence Methods

Sohn, Jie Ohn,Jo, Yoon Mi,Park, Hye Jin,Ahn, Ji Yeon,Song, Hyun Jin,Lim, Jeong Mook,Lee, Seung Tae The Korean Society of Embryo Transfer 2016 한국동물생명공학회지 Vol.31 No.1

An in vitro assay following culture of endometrial epithelial cells is essential for understanding epithelial cell function in reproduction. Several diverse techniques have been developed for isolating endometrial epithelial cells, although an optimal technique has not been identified. In this study, we describe a sedimentation-adherence (S-A) isolation technique with a high-yield cell-separating ability to isolate endometrial epithelial cells from 8-week-old female C57BL/6 mice. We analyzed total cell number, viability, morphology, and expression of cytokeratin 18 as an endometrial epithelial cell-specific marker in cells isolated using a mechanical method compared to the S-A technique. There were no significant differences in the total number, viability, or morphology of the putative endometrial epithelial cells with either method. In contrast, significantly more endometrial epithelial cells harvested using the S-A method were positively stained for cytokeratin 18 than those isolated using the mechanical method. These results confirm that the S-A method is more efficient for retrieving endometrial epithelial cells than a mechanical method.

Identification of a High-yield Technique for Isolating EndometrialEpithelial Cells from the Mouse Uterus :A Comparison of Mechanical and Sedimentation-adherence Methods

손지온,조윤미,박혜진,안지연,송현진,임정묵,이승태 사단법인 한국동물생명공학회 2016 한국동물생명공학회지 Vol.31 No.1

An in vitro assay following culture of endometrial epithelial cells is essential for understanding epithelial cell function in reproduction. Several diverse techniques have been developed for isolating endometrial epithelial cells, although an optimal technique has not been identified. In this study, we describe a sedimentation-adherence (S-A) isolation technique with a high-yield cell-separating ability to isolate endometrial epithelial cells from 8-week-old female C57BL/6 mice. We analyzed total cell number, viability, morphology, and expression of cytokeratin 18 as an endometrial epithelial cell-specific marker in cells isolated using a mechanical method compared to the S-A technique. There were no significant differences in the total number, viability, or morphology of the putative endometrial epithelial cells with either method. In contrast, significantly more endometrial epithelial cells harvested using the S-A method were positively stained for cytokeratin 18 than those isolated using the mechanical method. These results confirm that the S-A method is more efficient for retrieving endometrial epithelial cells than a mechanical method.