• Journal of Korean Port Research
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• v.13 no.1
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• pp.155-166
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• 1999

The construction of the coastal structures and reclamation work causes the circulation reduced in the semi-closed inner water area and the unbalanced sediment budget of beach results in an alteration of beach topography. Among the various fluid motions in the nearshore zone water particle motion due to wave and wave-induced currents are the most responsible for sediment movement. Therefore it is needed to predict the effect of the environmental change because of development and so the prediction of wave transformation dose. The purpose of this study is to introduce the relation between waves wave-induced currents and sediment movement. In this study we will show numerical method using energy conservation equation involving reflection diffraction and reflection and the surfzone energy dissipation term due to wave breaking is included in the basic equation. For the wave-induced current the momentum equation was combined with radiation stresses lateral mixing and friction Various information is required in the prediction of wave-induced current depending on the prediction tool. We can predict changes in wave-induced current from the distribution of wave especially near the wave breaking zone. To evaluate these quantities we have to know the local condition of waves mean sea level and so on. The results from the wave field and wave-induced current field deformation models are used as input data of the sediment transport and bottom change model. Numerical model were established by a finite difference method then were applied to the development plan of the eastern Pusan coastal zone Yeonhwa-ri and Daebyun fishing port. We represented the result with 2-D graphics and made comparison between before and after development.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.1
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• pp.71-81
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• 2011

Due to increased human activities and intensive rainfall events in a watershed, soil erosion and sediment transport have been hot issues in many areas of the world. To evaluate soil erosion problems spatially and temporarily, many computer models have been developed and evaluated over the years. However, it would not be reasonable to apply the model to a watershed if topography and environment are different to some degrees. Also, source codes of these models are not always public for modification. The ArcGIS model builder provides ease-of-use interface to develop model by linking several processes and input/output data together. In addition, it would be much easier to modify/enhance the model developed by others. Thus, simple model was developed to decide soil erosion hot spot areas using ArcGIS model builder tool in this study. This tool was applied to a watershed to evaluate model performance. It was found that sediment yield was estimated to be 13.7 ton/ha/yr at the most severe soil erosion hot spot area in the study watershed. As shown in this study, the ArcGIS model builder is an efficient tool to develop simple models without professional programming abilities. The model, developed in this study, is available at http://www.EnvSys.co.kr/~sateec/toolbox for free download. This tool can be easily modified for further enhancement with simple operations within ArcGIS model builder interface. Although very simple soil erosion and sediment yield were developed using model builder and applied to study watershed for soil erosion hot spot area in this study. The approaches shown in this study provides insights for model development and code sharing for the researchers in the related areas.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.253-257
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• 2007

Channel-aquifer interaction is one of the key hydrological processes that determine water flows in the stream/river channel. Field measurements of channel-aquifer interaction, however, is very difficult and costly, particularly when one intends to understand its variations across a catchment for a long period. Hydrological simulations using a catchment model are a relatively easier and cheaper alternative provided the model structure is appropriate for describing channel-aquifer interaction. In this study, a catchment model called CAMEL (Chemicals from Agricultural Management and Erosion Losses) is used for estimating channel-aquifer interaction over time and space. CAMEL is a distributed catchment model to simulate transformation and transport processes of sediment and pollutants as well as water flows at the catchment scale. In the model, a catchment is represented using a network of square columns each of which is comprised of various storages of water. CAMEL explicitly simulates both surface and subsurface processes including channel-aquifer interaction. This paper presents an application study results of CAMEL for the Tarland Burn Catchment, a small (catchment area $52\;km^2$) rural catchment in Scotland, UK, demonstrating some of the channel-aquifer interaction dynamics across the catchment during a 2-year period.

• 한국해양학회지
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• v.26 no.1
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• pp.38-46
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• 1991

size data of 1,044 surface sediments from Korean shelf area were compiled and reexamined. Size distribution curves of the sediments are unimodal (31% of the total number), bimodal (54%), or multimodal 915%), Size curves of the sediments and modal subpopulations of the mixed sediments show resemblance to normal curve in shape. The modal mean value shows systematic change along a direction inside the Recent mud belts of the southeastern Yellow Sea and west of Korea Strait. It was found that the areas covered by unimodal sand are minimal value areas of heavy metal and suspended sediment-concentration in the southeastern Yellow Sea and northern East China transport processes during Recent time. It was also found that the mode analysis is useful method to extract information from sediment size data.

• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.15-23
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• 2010

Debris flows are a natural hazard which looks like a combination of flood, land and rock slide. Large rainfall in July 2006 produced several large scale debris flows and many small debris flows that resulted in loss of life and considerable property and railway damage, as was widely reported in the national media. The hazard "debris flow" is still insufficiently researched. Furthermore debris flows are very hard to predict. Flexible Ring net barriers are multi-functional mitigation devices commonly applied to rock fall or floating wood protection in floods, snow avalanches and also mud flows or granular debris flows, if properly dimensioned for the process or processes for which they are intended. Overtopping of the barriers by debris flows and sediment transport is possible, supporting the design concept that a series of barriers may be used to stop volumes of debris larger than are possible using only one barrier. The future for these barrier concepts looks promising because these barriers represent the state of art for such applications and are superior to many other available options.

• Water Engineering Research
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• v.1 no.3
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• pp.171-185
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• 2000

A mathematical model to adequately predict complex mixing characteristics of sorptive polluants in natural streams with pools-and-riffes has been developed. In this model, sorption of pollutants onto the bed sediment as well as mass storage and exchange in the storage zones were incorporated into one-dimensional mass balance equatins. The geometric and hydraulic characteristics of the pool-riffle sequences were properly conceptualized. Simulations with parameters of pool-and-riffle streams better fit the measured data in overall shape and peak concentration than simulations with parameters for uniform channels. The analyses on the characteristics of the storage zone model parameters reveal that a linear relationship between the logrithm of the storage zone volume ratio and a function of the friction factor exists. A linear relatiohship might also be tenatively assumed between the logarithm of the dimensionless mass exchange coefficient and the logarithm of the aspect ratio of the storage zone if some of the high values of the dimensionless mass exchange coefficient collected on the successive bed forms are excluded.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.815-829
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• 2008

Debris flows are a natural hazard which looks like a combination of flood, land and rock slide. Large rainfall in July 2006 produced several large scale debris flows and many small debris flows that resulted in loss of life and considerable property and railway damage, as was widely reported in the national media. The hazard "debris flow" is still insufficiently researched. Furthermore debris flows are very hard to predict. Flexible Ring net barriers are multi-functional mitigation devices commonly applied to rock fall or floating wood protection in floods, snow avalanches and also mud flows or granular debris flows, if properly dimensioned for the process or processes for which they are intended. Overtopping of the barriers by debris flows and sediment transport is possible, supporting the design concept that a series of barriers may be used to stop volumes of debris larger than are possible using only one barrier. The future for these barrier concepts looks promising because these barriers represent the state of art for such applications and are superior to many other available options.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.15-20
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• 2010

The contamination loadings generated in Changwon City are coming into Masan Bay through the Bongam tidal flat except the loadings collected and transferred by sewer lines to the wastewater treatment plant. The recovery of waterbirds, shellfishes, and fishes has been quite well recognized in recent years after the first implementation of Masan Bay TPLM (Total Pollution Loads Management) in Korea. This tidal flat has been conserved by the cooperation of several stakeholders and utilized as an ecosystem field site for in situ education. A large industrial complex has been operated since 1970's, therefore increasing the level of pollutants in estuary and costal sediments, especially by heavy metals. Zinc, copper, and lesd contamination of sediment was revealed at higher level by Clean-up guideline (MOMAF) or heavily polluted level by SQC (USEPA). There was a significant difference between two sites at the 95% confidence level, which implies no homogeneity in the processes of transport and deposition even at 500 m of distance. The heavy metal concentrations in the Bongam sediments have been gradually decreased with comparing the data of 2006, and 2009.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.2
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• pp.53-61
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• 1997

The interface system, GIS-AGNPS was to be validated with field data from six tested small watersheds ranging from 0.7 to 4.7$km^2$ in size which have steep topography and complex landuses. The model validation involved the calibration of input parameters and component modifications, in efforts to develop a model applicable to general uses for identifying and controlling nonpoint source pollution loads from agricultural watersheds. The simulated direct runoff from AGNPS was in good agreement with the field data for the averaged antecedent moisture conditions or AMC- II. The results differed, however, from the observed for AMC- I or III. A simple empirical relationship was proposed to estimate the curve number for AMC- I or m from AMC- II, which was found to result in simulated runoff close to the observed. The peak runoff relationship at AGNPS was also modified to reflect the watershed conditions and tested satisfactorily with the field data. The simulated sediment yields from the watersheds were fair as compared to the observed. Nutrient loads simulated from the model were different from the observed data. It appeared that the model was incapable of adequate depicting nutrient transport processes at paddy field and other landuses of the tested watersheds. Some modifications may be needed for the accurate representing the processes at paddy field.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.446-457
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• 2020

Crescentic sand bar in the coastal zone of eastern Korea is a common morphological feature and the rhythmic patterns exist constantly except for high wave energy events. However, four consecutive typhoons that directly and indirectly affected the East Sea of Korea from September to October in 2019 impacted the formation of longshore uniform sand bar and overall shoreline retreats (approx. 2 m) although repetitive erosion and accretion patterns exist near the shoreline. Widely used XBeach to predict storm erosions in the beach is utilized to investigate the morphological response to a series of storms and each storm impact (NE-E wave incidence). Several calibration processes for improved XBeach modeling are conducted by recently reported calibration methods and the optimal calibration set obtained is applied to the numerical simulation. Using observed wave, tide, and pre & post-storm bathymetries data with optimal calibration set for XBeach input, XBeach successfully reproduces erosion and accretion patterns near MSL (BSS = 0.77 (Erosion profile), 0.87 (Accretion profile)) and observed the formation of the longshore uniform sandbar. As a result of analysis of simulated total sediment transport vectors and bed level changes at each storm peak Hs, the incident wave direction contributes considerable impact to the behavior of crescentic sandbar. Moreover, not only the wave height but also storm duration affects the magnitude of the sediment transport. However, model results suggest that additional calibration processes are needed to predict the exact crest position of bar and bed level changes across the inner surfzone.