• Title/Summary/Keyword: Erosion depth

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Effects of Soil Covering Depth and Vegetation Base Materials on the Growth of Lespedeza cyrtobotrya Miq. in Abandoned Coal Mine Land in Gangwon, Korea (폐석더미에서 복토 및 식생기반재 처리가 참싸리(Lespedeza cyrtobotrya Miq.)의 생장에 미치는 영향)

  • Kim, Jeong-Hwan;Lim, Joo-Hoon;Yi, Koong;Lee, Im-Kyun;Jeong, Yong-Ho
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.15 no.6
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    • pp.61-67
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    • 2012
  • This study was conducted to evaluate the effects of soil covering and vegetation base materials implementation on the growth of Lespedeza cyrtobotrya Miq. in abandoned coal mine land. We compared the biomass of L. cyrtobotrya at the study plots of four different soil covering depth (control, 10cm, 20cm, and 30cm) and four different compounds of vegetation base materials composed of soil conditioner (S), erosion control (E), and peat moss (P) (control, S+P, E+P, and S+E+P). The result showed that the biomass of L. cyrtobotrya was higher in the study plots implemented with soil covering than control plot, although the increase in biomass was not constant with soil covering depth. In case of the vegetation base materials treatments, the biomass was highest in S+E+P plot, and S+P and E+P plots showed higher biomass than control plot.

Analysis of Hydraulic Characteristics According to the Cross-Section Changes in Submerged Rigid Vegetation

  • Lee, Jeongheum;Jeong, Yeon-Myeong;Kim, Jun-Seok;Hur, Dong-Soo
    • Journal of Ocean Engineering and Technology
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    • v.36 no.5
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    • pp.326-339
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    • 2022
  • Recently, not only Korea but also the world has been suffering from problems related to coastal erosion. The hard defense method has been primarily used as a countermeasure against erosion. However, this method is expensive and has environmental implications. Hence, interest in other alternative methods, such as the eco-friendly vegetation method, is increasing. In this study, we aim to analyze the hydraulic characteristic of submerged rigid vegetation according to the cross-sectional change through a hydraulic experiment and numerical simulation. From the hydraulic experiment, the reflection coefficient, transmission coefficient, and energy dissipation coefficient were analyzed according to the density, width, and multi-row arrangement of the vegetation zone. From numerical simulations, the flow field, vorticity distribution, turbulence distribution, and wave distribution around the vegetation zone were analyzed according to the crest depth, width, density, and multi-row arrangement distance of the vegetation zone. The hydraulic experiment results suggest that the transmission coefficient decreased as the density and width of the vegetation zone increased, and the multi-row arrangement condition did not affect the hydraulic characteristics significantly. Moreover, the numerical simulations showed that as the crest depth decreased, the width and density of vegetation increased along with vorticity and turbulence intensity, resulting in increased wave height attenuation performance. Additionally, there was no significant difference in vorticity, turbulence intensity, and wave height attenuation performance based on the multi-row arrangement distance. Overall, in the case of submerged rigid vegetation, the wave energy attenuation performance increased as the density and width of the vegetation zone increased and crest depth decreased. However, the multi-row arrangement condition did not affect the wave energy attenuation performance significantly.

MODIFICATION OF METAL MATERIALS BY HIGH TEMPERATURE PULSED PLASMA FLUXES IRRADIATION

  • Vladimir L. Yakushin;Boris A. Kalin;Serguei S. Tserevitionov
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2000.05a
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    • pp.1-1
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    • 2000
  • The results of the modification of metal materials treated by high temperature pulst:d plasma fluxes (HTlPPF) with a specific power of incident flux changing in the $(3...100)10^5{]\;}W/cm^2$ range and a pulse duration lying from 15 to $50{\;}\mu\textrm{s}$ have been presented. The results of HTPPF action were studied on the stainless steels of 18Cr-l0Ni, 16Cr- 15Ni, 13Cr-2Mo types; on the structural carbon steels of (13...35)Cr, St. 3, St. 20, St. 45 types; on the tool steels of U8, 65G, ShHI5 types, and others; on nickel and high nickel alloy of 20Cr-45Ni type; on zirconium- and vanadium-base alloys and other materials. The microstructure and properties (mechanical, tribological, erosion, and other properties) of modified materials and surface alloying of metals exposed to HTPPF action have been investigated. It was found that the modification of materials by HTPPF resulted in a simultaneous increase of several properties of the treated articles: microhardness of the surface and layers of 40...60 $\mu\textrm{m}$ in depth, tribological characteristics (friction coefficient, wear resistance), mechanical properties ({\sigma_y}, {\;}{\sigma_{0.2}}.{\;}{\sigma_r}) on retention of the initial plasticity ($\delta$), corrosion resistance, radistanation erosion under ion irradiation, and others. The determining factor of the changes observed is the structural-phase modification of the near-surface layers, in particular, the formation of the fine cellular structure in the near-surface layers at a depth of $20{\;}{\mu\textrm{m}}$ with dimension of cells changing in the range from 0.1 to $1., 5{\;}\mu\textrm{m}$, depending on the kind of material, its preliminary treatment, and the parameters of plasma fluxes. The remits obtained have shown the possibility of purposeful surface alloying of metals exposed to HTPPF action over a depth up to 20...45 $\mu\textrm{m}$ and the concentration of alloying element (Ni, Cr, V) up to 20 wt.%. Possible industrial brunches for using the treatment have been also considered, as well as some results on modifying the serial industrial articles by HTPPF.

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Analysis of Ecological Function and Percent Passing of Erosion Control Dam by Openness (개방형에 따른 사방댐의 투과율 및 생태적 기능 분석)

  • Koo, Gil-Bon;Ma, Ho-Seop
    • Journal of agriculture & life science
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    • v.52 no.6
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    • pp.1-12
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    • 2018
  • This study was conducted to analyze the openness of erosion control dams situated near mountain stream. The ecological functions of erosion control dams analyzed by such openness for adequately protect and manage the diversity of species and to prevent disasters. The obtained results were as follows. When structurally modifying or changing non-permeable, gravity type dams with a passing rate of less than 1% into open-type dams, the passing rate increased by about 77 times more from 0.72% to 55.8%. Except for closed, gravity type erosion control dams that are constructed with a special purpose such as creating sand deposits and reservoirs, there is a need to construct and improve the dams into permeable type dams that can relatively satisfactorily perform various functions such as carrying soil and sand to the downstream region and create a ecological corridor upstream and downstream for fish and amphibians. The openness based on the blocking height of the erosion control dam varies depending upon the height of the base part and the depth of the substructural part. It must be designed based on the on-site conditions and the purpose of the construction. The functional types of erosion control dams based on the open form of the cross-section as follows: the fish traffic type, flood control type, reservoir type for forest fire control), non-permeability type for soil and rock blocking, net type for blocking the rock flow and the particle screen type.

Two-dimensional Thermal Analysis for Carbonacious Thermal Liner of Rocket Nozzle with Ablation and In-depth Pyrolysis (삭마 및 내부 열분해를 고려한 로켓노즐 탄소계 내열재의 2차원 열해석)

  • 황기영;강윤구
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.2
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    • pp.37-47
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    • 1999
  • This paper describes the thermal analysis which can calculate the ablation depth and temperature distribution of the rocket nozzle liner allowing geometry change caused by the ablation of nozzle liner. In this analysis, Zvyagin's model is used for surface ablation and Yaroslavtseva's model for in-depth pyrolysis. A deforming finite-element grid is used to account for external-boundary movement due to the erosion of thermal liner. The accuracy of the present numerical method is evaluated with a rocket nozzle liner and the numerical solutions are favorably agreed with experimental data. The temporal variations of temperature and ablation depth at the thermal liner of another rocket nozzle are numerically simulated and the results are discussed. Special emphasis is given to the effects of kinetic constants for carbon-carbon and carbon-phenolic composites on the ablation depth of thermal liner.

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Monitoring of Coastal Erosion and Accretion Changes using Sea Walls Surveying (호안측량에 의한 해안침식 및 퇴적 변화량 모니터링)

  • Lee, Hyung-Seok;Um, Dae-Yong;Jang, Eun-Suk
    • Journal of the Korean Association of Geographic Information Studies
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    • v.8 no.2
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    • pp.186-195
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    • 2005
  • Topography of beach line is keeping stability for several years, their soil values have been maintained in balances. Install of coastal structures have caused deformation for beaches and acted as a function to structures. Therefore, quantitative prediction of beaches topography according to structure install is required to prevent the beaches deformation and progress proper coastal preservation work. In this study, we analyzed coastal changes caused by erosion and accretion according to development and drew up a cross-section to share 8 stations using coordinates and depth surveying in groin of Soheuksan island port. Elevation distribution and changes by observation period is calculated -0.30m~+0.20m after comparing results of five months in October 7, 2004 surveying results and fell into insignificance. We thinks periodic observation of coastal erosion and accretion take place for the season and long-term coastal changes in beaches width is analyzed.

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A Laboratory Study on Erosional Properties of the Deposit Bed of Saemankeum Sediments (새만금 점착성 퇴적물의 퇴적저면 침식특성에 관한 실험적 연구)

  • Yang, Su-Hyun;Lee, Seung-Jong;Hwang, Kyu-Nam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.2
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    • pp.105-112
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    • 2015
  • In this study, the erosional properties of deposit bed for the natural sediments are quantitatively estimated domestically for the first time using annular flume. Four erosion tests for Saemankeum sediments have been carried out on different consolidation time. Experimental results of erosional tests show that shear strength ${\tau}_s$ increases with the increases of consolidation time and bed depth. The erosion rate increases logarithmically with the increases of exceed shear strength ${\tau}_b-{\tau}_s$. But, the erosion rate decreases rapidly with the decreases of exceed shear strength under the $0.2N/m^2$. Experimental results of this study are found to be remarkably different in quantity as compared with those for results of previous study.

An Applied Case to the Slope Revegetation Technology of Biological Engineering Regarding Nutritional Propagation - In the case of sandy cut-slope - (버드나무의 영양번식을 이용한 생물공학적 사면녹화공법의 적용사례 - 토사로 구성된 절토면을 대상으로 -)

  • Kim, Hyea-Ju;Lee, Joon-Heon
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.1 no.1
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    • pp.63-69
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    • 1998
  • The slope revegetation methods in Korea are generally the hydroseeding mixed with perennial herbs, soil, fibers, and fertilizer in consideration of scenic landscape rather than ecological and engineering effect. But perennial herbs can't protect the slope from deep surface erosion and they are not tall enough to create the original naturalness at the boundary parts of existing woodlands. This study is about the slope revegetation method using nutritional propagation capacity of plants and the experimental construction was carried out on the cut-slope of Yongin Hoam C.C. We dug several trenches to a depth of 80cm and at intervals of 150cm from each other. After placing various kinds of live branches(Salix species) into the trench, we backfilled with the excavated soils and finally sprayed water mixed with soil-stabilizer, fertilizer. As six months passed, we made a vegetation research and check the slope surface erosion. Vegetation research was performed in examining the frequency of each block using transect method. 31 kinds of plant species appeared in total area($113.6m^2$) and the dominant species are Setaria viridis, Artemisia rubripes, Persicaria pubescens, Plantago asiatica, Cyperus amuricus, Commelina communis. Among the examined blocks, '아', the top part of the slope, showed the ratio of 1.4 as the highest Alpha-diversity. With regard to life form, therophytes were shown dominant distribution of 58% of total species and neophytes relatively low distribution of 16%. It can be estimated that there is no ecological stabilization of this slope, because of ruderal species' occupation of 74% in total area. Regarding the slope stabilization, the serious surface erosion didn't take place in spite of heavy rainfall this year, but a little surface erosion took place at the block where no other species coming from outside of the site were found.

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Numerical Experiment of Debris Flow and Driftwood Behavior with Entrainment Erosion (연행침식을 고려한 토석류와 유목거동의 수치실험)

  • Kang, Tae Un;Jang, Chang-Lae;Kimura, Ichiro;Lee, Nam Joo
    • Ecology and Resilient Infrastructure
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    • v.9 no.3
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    • pp.141-153
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    • 2022
  • In this study, a numerical model of debris flow considering driftwood and entrainment erosion is developed. Subsequently, numerical simulations based on the observation data of the 2011 Mt. Umyeon are performed. To develop the debris flow model, the Nays2DFlood model, which is a flooding model based on the shallow water equation, is coupled with the transport diffusion of mixed sediment concentration, debris flow bottom shear stress, and entrainment erosion modules. The simulation closely reproduced the depth, flow velocity, and debris flow volume of Mt. Umyeon. In addition, the reproducibility of the simulation result with driftwood is more accurate than that without driftwood. The results of this study can facilitate in establishing measures to reduce debris disasters, thus alleviating the current increase in debris damage due to climate change.

Sensitivity Analysis in the Prediction of Coastal Erosion due to Storm Events: case study-Ilsan beach (태풍 기인 연안침식 예측의 불확실성 분석: 사례연구-일산해변)

  • Son, Donghwi;Yoo, Jeseon;Shin, Hyunhwa
    • Journal of Coastal Disaster Prevention
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    • v.6 no.3
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    • pp.111-120
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    • 2019
  • In coastal morphological modelling, there are a number of input factors: wave height, water depth, sand particle size, bed friction coefficients, coastal structures and so forth. Measurements or estimates of these input data may include uncertainties due to errors by the measurement or hind-casting methods. Therefore, it is necessary to consider the uncertainty of each input data and the range of the uncertainty during the evaluation of numerical results. In this study, three uncertainty factors are considered with regard to the prediction of coastal erosion in Ilsan beach located in Ilsan-dong, Ulsan metropolitan city. Those are wave diffraction effect of XBeach model, wave input scenario and the specification of the coastal structure. For this purpose, the values of mean wave direction, significant wave height and the height of the submerged breakwater were adjusted respectively and the followed numerical results of morphological changes are analyzed. There were erosion dominant patterns as the wave direction is perpendicular to Ilsan beach, the higher significant wave height, and the lower height of the submerged breakwater. Furthermore, the rate of uncertainty impacts among mean wave direction, significant wave height and the height of the submerged breakwater are compared. In the study area, the uncertainty influence by the wave input scenario was the largest, followed by the height of the submerged breakwater and the mean wave direction.