• Journal of Korea Water Resources Association
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• v.38 no.4 s.153
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• pp.313-321
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• 2005

The elimination and erosion of cohesive sediments in port and reservoir water can so far be processed only with mechanical evacuation methods under extreme energy expenditure. The so-called flushing jets do not serve the purpose because they cannot set the material spaciously in motion despite high shear stresses at the bed. Therefore this study aims to examine the resuspension of the deposited fine material($Al_{2}O_3$) under presence of gas bubbles in order to decreased cohesive sediments in multipurpose dam, port and lakes. In the case of laboratory trial important parameters considered are supplied amount of air and the consolidation time of the solid materials. With increasing gas content alumina remains in suspension at high pH values in the laboratory test, where the particles fall mote rapidly without air addition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.1
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• pp.36-44
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• 2006

Cohesive sediment transport in coastal region has been studied by numerical modeling. A finite element numerical model was setup to simulate hydrodynamics and sediment transport in the coastal region with complex topography. Only physical features of observed sediments has been used to determine erosion rates of bottom sediments together with the previous research results. The simulation results using the simply determined equation of erosion rates were compared with time variations of the observed SS concentration and showed good agreements. In conclusion, this method can be used to estimate transport of cohesive sediment conveniently.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.233-243
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• 2015

The bimodal flocculation of cohesive sediments in water environments describes the aggregation and breakage process developing a bimodal floc size distribution with dense flocculi and floppy flocs. A two class population balance equation (TCPBE) was tested for simulating the bimodal flocculation by a model-data fitting analysis with two sets of experimental data (low and high turbulent flows) from 1-D flocculation-settling column tests. In contrast to the Single-Class PBE (SCPBE), the TCPBE could simulate interactions between flocculi and flocs and the flocculation mechanism by differential settling in a low turbulent flow. Also, the TCPBE could perform the same quality of simulation as the elaborate Multi-Class PBE (MCPBE), with a small number of floc size classes and differential equations. Thus, the TCPBE was proven to be the simplest model that is capable of simulating the bimodal flocculation of cohesive sediments in water environments and water, wastewater treatment systems.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05b
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• pp.1075-1080
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• 2002

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05b
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• pp.1111-1116
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• 2002

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.2
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• pp.119-128
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• 2005

An annular flume has been constructed in order to estimate the erosion rate of fine cohesive sediments. Under an uniform bed condition, some erosion tests for Kaolinite sediments have been conducted to examine the performance of the flume and to check the validity of experimental method and results. In this study, the critical shear stress for erosion and the erosion rate coefficient are estimated and compared with the existing measurements. It is concluded that the performance of the annular flume is good enough to conduct erosion tests and the experimental method and results are valid.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.5
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• pp.327-334
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• 2014

This study aims to estimate settling velocity ($W_s$) for cohesive sediments from water bodies (Incheon Coast, Kulpo Stream and Han River) mainly connected to the Kyeongin Ara-waterway through the laboratory settling experiments. Results of settling tests for these sediments show that $W_s$ values for sediments are quite different each other: $W_s$ values of Kulpo Stream sediments (0.01 < $W_s$ < 3.07 mm/s) are quite similar with those of Han River sediments (0.01 < $W_s$ < 2.97 mm/s) over the whole range of suspension concentration C (0.1 < C < 90 g/ L), while they are quite different with those for Incheon Coast sediments (0.01 < $W_s$ <0.92 mm/s). Qualitative analyses on test results for physico- chemical properties of sediments and waters with respect to settling velocities show that these differences in settling velocities are mainly due to the salinity difference in the water.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.475-484
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• 2002

A series of settling tests and physico-chemical property tests on Saemankeum fine-cohesive sediments has been conducted in order to investigate the correlation between settling properties and their physico-chemical properties which are represented as grain size distribution, mineralogical composition, and percentage of organic contents. Experimental results of physico-chemical property tests show that Saemankeum sediments are relatively large in average grain size(52${\mu}{\textrm}{m}$), and contain very small organic materials(2%), and are dominantly composed of Quarts in mineralogical aspect which has relatively low cohesion. Thus, Saemankeum sediments might be specified as the sediments whose settling properties are more influenced by the gravity than the cohesion. This characteristics of Saemankeum sediments are found to lead to relatively small settling velocity in flocculated settling region in which increasing cohesion results in increasing settling velocity, while relatively large settling velocity in hindered settling region in which settling velocity decreases with increasing cohesion.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.140-145
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• 2010

Consolidation in cohesive soils mainly focuses on compressibility of soils, but it affects solute transport in some cases. The consolidation process takes on particular significance for fine grained soils at high water content, such as dredged sediments, but has also been shown to be important for compacted clay liners during waste filling operation. Numerical investigation using CST1 and CST2 was reviewed on consolidation-induced solute transport in this paper, especially with the development of CST2 model, verification by comparing experimental results with numerical simulations, and cases studies regarding transport in a confined disposal facility (CDF) and during in-situ capping. The importance of the consolidation process on solute transport is accessed based on simulated concentration or mass breakthrough curves. Results indicate that neglecting transient consolidation effects may lead to significant errors in transport analyses, especially with soft contaminated cohesive soils undergoing large volume change.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1992.08a
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• pp.158-165
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• 1992

Bottom sediments, in various types of sediment transport models, have been usually assumed to be horizontally and/or vertically homogeneous. The assumption may be appropriate in well-sorted sedimentary environments including sand beaches and high turbid regions of fine grained cohesive sediments. (omitted)