• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.57-69
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• 1995

The development of a finite difference model for cross-shore sediment transport prediction in the surf tone due to the storm surge event is presented in this paper. Using the inhomogeneous diffusion equation with moving boundaries. the present numerical model is found to be robust and efficient and does not possess a number of restrictions imposed in Kriebel and Dean's(1985) numerical model. Our numerical model is validated through comparison with the analytical solution. the data of a large-scale experiment and the field data of Hurricane Eloise. The Present model if able to predict the averaged volumetric erosion rate of a beach due to the time-varying real storm surge hydrographs and satisfies the conservation of sediment between eroded volume in the onshore region and deposited volume in the offshore region. In addition. the present model is able to reasonably predict the recession of a beach with wide berm and dune. and can describe the change of a breaking point by the offshore deposition. From the sensitivity analysis or the present numerical model with various input parameters, it is concluded that the present numerical model is able to analyze the beach change in a reliable manner including the effects of different sizes of sediments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5B
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• pp.467-474
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• 2011

Debris flow is one of the most hazardous natural processes in mountainous regions. The degradation of discharge capacity of drainage facilities due to debris flows may result in damages of properties and casualty as well as road. Understanding and accurate reproducing flow behaviour of debris flows at various conditions, such as sediment volume concentration and approaching channel and culvert slopes, are prerequisite to develop advanced design criteria for drainage facilities to prevent such damages. We carried out a series of laboratory experiments of debris flows in a rectangular channel of constant width with an abrupt change of bottom slope. The experimental flume consists of an approaching channel part with the bed slope ranging $15^{\circ}$ to $30^{\circ}$ and the test channel with slope ranging from $0^{\circ}$ to $12^{\circ}$ which mimics a typical drainage culvert. The experiments have been conducted for 22 test cases with various flow conditions of channel slopes and sediment volume concentration of debris flows to investigate those effects on the behaviour of debris flows. The results show that, according to sediment volume concentration, the depth of debris flow is approximately 50% to 150% larger than that of fresh water flow at the same flow rate. Experimental results quantitatively present that flow behaviour and deposit history of debris flows in the culvert depend on the slopes of the approaching and drainage channels and sediment volume concentration. Based on the experimental results, furthermore, a logistic model is developed to find the optimized culvert slope which prevents the debris flow from depositing in the culvert.

• Clean Technology
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• v.10 no.1
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• pp.1-7
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• 2004

In this study, the performance of Aluminium foil etching waste(PWF100) as a cohesive agent was estimated and the methods to commercialize it were investigated through comparison of physical properties between Aluminium foil etching waste(PWF100) and commercial cohesive agent(PAC17). The height of sediment bed was measured according ot the change of the concentration of BKN-100, BKR-110, and BKR-120 prepared by using PWF100. When the concentrations of BKN-100, BKR-110, and BKR-120 were increased, the heights of sediment bed were constant after decreased. Also, the density of sediment bed was investigated according to the change of the concentration of BKN-100. When the concentrations of BKN-100 were increased, the densities of sediment bed were decreased. In addition, based on the concentration of BKN-100, BKR-110, and BKR-120, the sediment rate was experimented. When the concentrations of BKN-100, BKR-110, and BKR-120 were increased, sediment rates were rapid and then slow. Moreover, the volumes of sediment bed were measured according to the change of the concentration of BKN-100. According to increasing the concentrations of BKN-100, the required time for getting to the minimum volume of sedment bed were reduced and then increased. Lastly, the required time for sedimentation based on the concentration of BKN-100, BKR-110, and BKR-120 was investigated. When the concentrations of BKN-100, BKR-110, and BKR-120 were increased, the required times for sedimentation were increased after decreased. From these results, it can be concluded that the PWF100 acts as a cohesive agent.

• Land and Housing Review
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• v.8 no.3
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• pp.161-169
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• 2017

In this study, sediment transfer and precipitation analysis of the test bed watershed was conducted through the model for the application and practical use of the urban sediment disaster prevention technology, and used this as an aid to design to secure reliability. In addition, conducted the test bed monitoring with the defense technology, analyzed the effect, and established the maintenance plan. Analyzed the change of soil deposition volume through arbitrary slope adjustment for the currently installed stormwater conduit of the test bed watershed. As a result, it is important to reduce the total sedimentation amount in the adjustment of the slope of the entire pipeline, but it is important that the sedimentation depth of each sediment does not rise to such a degree as to threaten the performance of the pipeline. Considering these matters, it is necessary to design the pipeline to prevent the clogging of the soil from the viewpoint of the reliability of the entire pipeline. The sediment disaster defense technology test bed is divided into a new city and an old city, and old city test bed is under construction. The result obtained through the monitoring of the test bed in the new city, sediment disasters such as debris can delay the time to reach the downtown area, and it is possible to secure the golden time, such as evacuation and rescue through the warning system. Also, the maintenance of the test bed application was suggested. Continuous and systematic monitoring is required for securing the reliability of element technology and successful commercialization.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.155-165
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• 2003

A series of one-dimensional cylinder sedimentation test, seepage consolidation test and two-dimensional deposition model test were conducted to examine the characteristics of deposition and volume change of dredged soils containing the high water content, and these experimental results were compared with the sedimentary conditions of actual dredged-reclaimed fields to obtain the relations of a volume change by settling what is required for design. In addition, the change of water content and the distribution of fine grained soils after sedimentation were investigated. Thus, it was concluded that deposition height increased lineary as substantial soil volume increased, and also the elevation of interface increasea proportionately at both the starting time and the finishing time of virtual self-weight consolidation in one-dimensional sedimentation. Furthermore, the two-dimensional model test results were shown to describe the plain distribution of water content and fine grained silt where dredged soil was deposited by two dimensional flowing, and the water content was distributed to wide range from the minimum water content 30% to maximum 180% according to the passed amount of №200 sieve percentage.

• Ocean and Polar Research
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• v.43 no.4
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• pp.307-320
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• 2021

Udo Rhodolith Beach is a small-scale, mixed sand-and-gravel beach embayed on the N-S trending rocky coast of Udo, Jeju Island, South Korea. This study analyzes the short-term topographic changes of the beach during the extreme storm conditions of four typhoons from 2016 to 2020: Chaba (2016), Soulik (2018), Lingling (2019), and Maysak (2020). The analysis uses the topographic data of terrestrial LiDAR scanning and drone photogrammetry, aided by weather and oceanographic datasets of wind, wave, current and tide. The analysis suggests two contrasting features of alongshore topographic change depending on the typhoon pathway, although the intensity and duration of the storm conditions differed in each case. During the Soulik and Lingling events, which moved northward following the western sea of the Jeju Island, the northern part of the beach accreted while the southern part eroded. In contrast, the Chaba and Maysak events passed over the eastern sea of Jeju Island. The central part of the beach was then significantly eroded while sediments accumulated mainly at the northern and southern ends of the beach. Based on the wave and current measurements in the nearshore zone and computer simulations of the wave field, it was inferred that the observed topographic change of the beach after the storm events is related to the directions of the wind-driven current and wave propagation in the nearshore zone. The dominant direction of water movement was southeastward and northeastward when the typhoon pathway lay to the east or west of Jeju Island, respectively. As these enhanced waves and currents approached obliquely to the N-S trending coastline, the beach sediments were reworked and transported southward or northward mainly by longshore currents, which likely acts as a major control mechanism regarding alongshore topographic change with respect to Udo Rhodolith Beach. In contrast to the topographic change, the subaerial volume of the beach overall increased after all storms except for Maysak. The volume increase was attributed to the enhanced transport of onshore sediment under the combined effect of storm-induced long periodic waves and a strong residual component of the near-bottom current. In the Maysak event, the raised sea level during the spring tide probably enhanced the backshore erosion by storm waves, eventually causing sediment loss to the inland area.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.41-46
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• 1998

The purpose of the study was changed of Flood Characteristics in Down stream of Keum River by the Keum River Estuary Dam Construction. The water surface slope of Kuem river after the Keum River Estuary Dam construction was steeper then before. The flood control capacity increase after construction. But, Increasing sediment in Kuem river will be decreased flesh reservoir volume for yield irrigation.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.107-117
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• 2024

The objective of this study is to estimate riverbed fluctuations and the volume of aggregate extraction attributable to climate change. Rainfall-runoff modeling, utilizing the SWAT model based on climate change scenarios, as well as long-term riverbed fluctuation modeling, employing the HEC-RAS model, were conducted for the Nonsan River basin. The analysis of rainfall-runoff and sediment transport under the SSP5-8.5 scenario for the early part of the future indicates that differences in annual precipitation may exceed 600 mm, resulting in a corresponding variation in the basin's sediment discharge by more than 30,000 tons per year. Additionally, long-term riverbed fluctuation modeling of the lower reaches of the Nonsan Stream has identified a potential aggregate extraction area. It is estimated that aggregate extraction could be feasible within a 2.455 km stretch upstream, approximately 4.6 to 6.9 km from the confluence with the Geum River. These findings suggest that the risk of climate crises, such as extreme rainfall or droughts, could increase due to abnormal weather conditions, and the increase in variability could affect long-term aggregate extraction. Therefore, it is considered important to take into account the impact of climate change in future long-term aggregate extraction planning and policy formulation.

• Journal of the Korean GEO-environmental Society
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• v.20 no.4
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• pp.23-29
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• 2019

Heavy rainfall is in causing debris flow by recent climate change and causes much damage in the downstream. The debris flow from the mountainous area runs to the downstream, repeating sedimentation and erosion, and appears as a fluidized soil-water mixture. Continuity equation and momentum equation were applied to analyze the debris flow with strong mobility, and the sedimentation and erosion velocity with fine particle fractions were also applied. This study is to analyze the behavior of debris flow at the downstream end for the variation of the amount of sediments can occur in the upstream of the mountain. Analysis of sediment volume concentration at the downstream end of the channel due to the variance of the length of pavement of the granulated soils resulted in the higher the supply flow discharge and the longer the length of pavement, the greater the difference in the level of sediment concentration and the earlier the point of occurrence of the inflection point. The results of this study will provide good information for determining the erosion-sedimentation velocity rate which can detect erosion and sedimentation on steep slopes.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.158-163
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• 2005

The purpose of this study was to observe the effect on the marine environment by the use of Nano-S. Nano-S was made to apply to improve the red tide bloom. The experiment was performed at round tank with volume of 180 L. Each tank was filled with an aggravated sediment about $14{\pm}1cm$ hight and sea water. The water flow-rate of tank was established on the rate of 6.25 L/hr. Sea water level was fitted to 40 cm, therefore the filled water was about 150 L. The sediment was stabilized during one week. Then the Nano-S and the red mud were added into each tank 0 kg(control), 1 kg(tank A), 2 kg(tank B), 5 kg(tank C) and 10 kg(tank D) each other. The quantity was fulfilled with 0 kg(control), 2.75 kg(tank A), 5.51 kg(tank B), 13.77 kg(tank C) and 27.55 kg(tank D) per square meter of sediment. The experiment was performed during 30 days. Water and sediment samples were collected from each tanks on the before 1hour and after 1, 3, 6, 12 hour and 1st, 3th, 5th, 7th, 10th, 15th, 30th day of the experiment period. The change of water and sediment quality was analyzed before and after applying the Nano-S and the red mud.