• The Korean Journal of Ceramics
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• v.5 no.1
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• pp.30-34
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• 1999

Particle settling behavior was studied by the computer simulation using simultaneous particle condensation and relaxation. This three-dimensional settling algorithm includes the estimation of powder sediment density. Density distribution through the powder sediment was compared and was agreed well with the experimental findings. Settling density depended strongly of the degree of particle relaxation. Sediment strength and isotropy also depended on the degree of particle relaxation. Sever particle bridging was found near sharp corners.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.1
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• pp.5-14
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• 2004

A feasibility of using Particle Entrainment Simulator (PES) to evaluate model variables describing sediment entrainment in a river system was investigated. PES in a laboratory was utilized to simulate the sediment resuspension phenomenon in the river and the subsequent relationship between shear rate and sediment entrainment was developed. The total suspended solids (TSS) data from PES was incorporated into statistical models in an effort to describe behaviors of net particle movement in the river. PES was found to be adequate for simulating particle entrainment phenomenon in a river system. Statistical analysis was used to assess propriety of PES data for predictive purposes. The results showed good relationships between PES results and system variables, such as average stream velocity and net particle movement.

• KCID journal
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• v.21 no.1
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• pp.99-108
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• 2014

This study investigated the effects of NPS(non point source) pollution reduction of sediment traps through field experiments. Various sizes of 4 sediment traps were applied in a upland field located in Gunwi and assessed the infiltration and storage effects as well as NPS pollution reduction effects of this technique. The characteristics of deposited soil in the sediment traps were also analyzed including distribution of particle size, soil texture, and chemical properties. The results showed that slightly different composition of soil particle size from each sediment trap with high proportion of 0.15mm and 0.25mm ranges of soil particle diameters, while the loamy sand is the main types of deposited soils in the sediment traps. Decreased NPS pollution were observed from the water quality analysis of the samples taken from the sediment traps. Further research need to be proceeded continuously to improve this technique in order to utilize on upland fields for management of agricultural NPS pollutions.

• Journal of Korea Water Resources Association
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• v.46 no.1
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• pp.87-97
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• 2013

The bed change model of HEC-RAS was used to predict the formation of a delta upon an influx of high-density sediment while taking the particle-size distributions of the suspended sediment and bed materials into account. The model was able to reasonably predict both the spatial-temporal distribution of the delta and the amount of deposited sediment according to the grain size. In addition, it was able to estimate the main type of grains that sediment at particular locations at particular times moderately well. It is expected that the simulation and the analysis considering these particle-size distributions of sediment will provide important information on planning and maintenance of the water resource related facilities.

• Journal of Environmental Health Sciences
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• v.20 no.4
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• pp.45-52
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• 1994

This study was performed to investigate the contents of six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) with respect to the particle sizes and depths in sediment collected at nine sites of the lower Kumho river. The mean Cd, Cr, Cu, Ni, Pb and Zn contents in sediment of all sites ranged from 1.59~5.32 mg/kg, 17.4~301.7 mg/kg, 23.2~399.9 mg/kg, 9.48~116.8 mg/kg, 31.1~294.1 mg/kg and 74.2~964.3 mg/kg, respectively. The highest heavy metal contents was generally found to be Zn and lowest was Cd. The mean contents of heavy metal by particle sizes (1.0~0.5, 0.5~ 0.25, <0.25 mm)was the highest in particle sizes less than 0.25 mm, but the coefficients of variation was lowest in particle sizes less than 0.25 mm. Mean contents and coefficient of variation by depths (0~5 cm, 5~10 cm, 10~15 cm) were generally found to be higher in the upper parts of sediment than in the lower parts of sediment. Organic substances were found to be higher as the particle sizes become more small. Moreover, contents of heavy metal increased with the amounts of organic substances in sediment.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.62-66
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• 2010

This study presents velocities of bedload sediment transport in both longitudinal and lateral directions and applied in considering morphological change of straight open channel. The velocities of particle motion have obtained by considering the forces balance acting on particles on the bed between the drag, tangential component of the immersed weight of the particle, and Coulomb's resistive forces. Numerical profiles of particle motion velocities reveals good agreement in comparison between this study and Kovacs and Parker (1994). The evaluated velocities components of particle transport are get used to estimate bedload transport rate in considering morphological change of straight open channel. For the application, numerical solution is applied to laboratory experiment which shows very close solution profiles between this study and observed data of a self-formed straight channel.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.45-50
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• 2002

This study presents a modeling method to predict fate of resuspended sediment in the development of deep-sea mineral resources. Resuspended deep-sea sediment during the development is considered a major environmental problem. In order to quantitatively analyze the resuspended sediment in the water column, particle size distribution (PSD) is considered an important factor. The model developed here includes PSD and coagulation process, as well as sedimentation process. Using the model, basic simulation was performed under representative environmental setting. The simulation showed the dynamics of change of particle size distribution for 50 m depth of water column up to 10 days of simulation time. Coagulation seemed an important factor in the fate of resuspended deep-sea sediment.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.1
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• pp.22-28
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• 2004

The fate and transport mechanism of pollutants which have affinities to particles, such as trace metals and some petroleum product based compounds, can be effectively explained by the movement of sediment. The sediment release from lands to adjacent water bodies due to rainfall events was investigated in an effort to predict the total suspended solids (TSS) concentrations in runoff. The contribution of sediment from land origin to the river TSS can be better understood by the relationship between TSS concentration and particle size in runoff. The sieve analysis was used to determine the particle size distribution and these results were incorporated into statistical models. The critical size of particles was set to $74{\mu}m$ which contributes to the river TSS concentration since fine particles (wash load) of the sediment in the runoff play the key role in constituting TSS in a water column of the river. Empirical relationships were developed to predict TSS in runoff from the percentage of the critical particle size and were proven statistically to be valid.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.323-329
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• 2004

In situ particle size and volume concentration of suspended sediment was measured at the mouth of Seomjin River Estuary In February 2001, using an optical instrument, 'LISST-100'. Time variation of in situ particle size and concentration shows: (1) during ebb tide, Seomjin River supplies relatively fine-grained particles with less-fluctuated, compared to during flood tide, and well-behaved concentrations following the tidal cycle; and (2) during flood tide, relatively coarse-grained particles with highly variable in size distribution and concentration flow upstream from Kwangyang Bay. This explains a poor correlation $(r^{2}=0.10)$ between sediment concentration and beam attenuation coefficient during flood and a high degree of correlation $(r^{2}=0.80)$ during ebb tide. Relatively fine grained and well defined, monotonous size distribution may promote the correlation between concentration and beam attenuation coefficient due to optical homogeneity of particles during ebb tide. Abundance of large aggregates with time-varying size and shape distributions may be mainly responsible for variations in optical properties of the sediment during flood tide, and thus may confound the relationship between the two variables. The difference in particle sizes and shapes between flood and ebb tides can also be observed on SEM images.

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.1-20
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• 2019

In order to establish appropriate policy to control sediment-associated problems, it is necessary to identify the physical characteristics of the reservoir sediments in particulate form in the Yeongsan River. Two time-integrated suspended sediment samplers were installed at Seungchon and Juksan weir on the upper and middle Yeongsan River in July 2012. Reservoir sediment samples were obtained at monthly intervals until October 2014. During the monitoring period, a total of 38 sediment samples were obtained and analyzed. Seasonal trends of suspended sedimentation rates and grain size distributions were examined based on variations in precipitation and discharge fluctuations. Moreover, stream flow characteristics, which has a great influence on the physical characteristics of the river sediment, was analyzed using flow duration curve for the period 2003-2019 at Naju gauging station. Sedimentation rates during summer, when heavy rainfall was concentrated due to the monsoonal front and typhoon, were very high, indicating the positive relationship between sediment concentration and discharge. Particle size analysis of the collected sediment showed that coarse silt and very fine sand-sized sediment dominated most of the Seungchon weir sediment. On the other hand, medium silt-sized sediment dominated the downstream Juksan weir except for a few summer samples. These results implied that the physical characteristics of the suspended sediment are determined not only due to flow fluctuations, but also with regard to the antecedent rainfall conditions, hillslope-channel connectivity, and the supply of materials from various contributing regions. This information about flow characteristics and temporal variations in reservoir sediment can be used for safe management of the weir and discussing the issues on the dismantling of the weirs.