• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.196-196
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• 2016

Landslide dam failure presents as a severe natural disaster due to its adverse impact to people and property. If the landslide dams failed, the discharge of a huge volume of both water and sediment could result in a catastrophic flood in the downstream area. In most of previous studies, breaching process used to be considered as a constructed dam, rather than as a landslide dam. Their erosion rate was assumed to relate to discharge by a sediment transport equation. However, during surface erosion of landslide dam, the sediment transportation regime is greatly dependent on the slope surface and the sediment concentration in the flow. This study aims to accurately simulate the outflow hydrograph caused by landslide dam by overtopping through a 2D surface flow erosion/deposition model. The lateral erosion velocity in this model was presented as a function of the shear stress on the side wall. The simulated results were then compared and it was coherent with the results obtained from the experiments.

• Geomechanics and Engineering
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• v.17 no.3
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• pp.227-236
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• 2019

In practice, the natural slopes are frequently with soils of spatial properties and irregular features. The traditional limit analysis method meets an inherent difficulty to deal with the stability problem for such slopes due to the normal condition in the associated flow rule. To overcome the problem, a novel technique based on the upper bound limit analysis, which is called the discretization technique, is employed for the stability evaluation of complex slopes. In this paper, the discretization mechanism for complex slopes was presented, and the safety factors of several examples were calculated. The good agreement between the discretization-based and previous results shows the accuracy of the proposed mechanism, proving that it can be an alternative and reliable approach for complex slope stability analysis.

• Bulletin of the Korean Chemical Society
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• v.15 no.3
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• pp.198-204
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• 1994

Chemical shifts in aqueous sodium dodecylsulfate(SDS) micellar solution solublizing phenol, catechol, resorcinol, hydroquinone have been measured to investigate solubilization properties. Proton nuclear magnetic resonance frequencies of solubilizates as well as those of the ${\alpha}$-methylene, middle methylene and terminal methyl of SDS shift linearly as a function of solubilizate concentration. From the plots of observed chemical shift (v) vs solubilizate concentration, slope (a) and solubilizate free chemical shift ($v_0$) are obtained. They are very informative to solubilization site of the systems. Catechol and phenol solubilized SDS and catechol solubilized dodecylpyridinium chloride(DPC), dodecyltrimethylammonium bromide(DTAB) systems are studied using the same method to compare head group effect and middle methylene proton signal splitting. It is proposed that phenol and catechol are inserted into micellar interior and the number of methylenes assigned to the higher field peaks is 5.0${\pm}$0.5.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.353-362
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• 2009

This study attempted to compare the litter decomposition rate of Arundinella hirta and Miscanthus sinensis var. purpurascens which collected from serpentine soil acting potentially toxic concentration of heavy metals and non-serpentine soil by using the microcosm method for 192 days under constant humidity and $23^{\circ}C$. The contents of Ni, Fe, Mg and Cr in the serpentine and nonserpentine soil originated litter showed high differences between them. The litter samples from serpentine site have lower C/N than non-serpentine litter, but the soluble carbohydrate content was shown almost similar between two plant litter. The mass loss rates of leaf litter from serpentine area were slower than those from non-serpentine site. During the experimental period, the remained dry weight of A. hirta and M. sinensis var. purpurascens litter collected from serpentine site were 64.7%, 65.0% of initial dry weight and litter samples from non-serpentine site showed 54.2%, 50.7%, respectively. K and Na were leached rapidly at the initial decomposition periods, but Ca showed immobilization and other metal elements reserved at the decomposing litter for a long time. The decomposing A. hirta litter from non-serpentine soil showed higher values of $CO_2$ evolution, microbial biomass-C, and microbial biomass-N than those in serpentine soil originated litter acting nutrient stresses and exhibited rapid decay rate. The microbial biomass and microbial respiration of decaying litter were positively correlated with litter decomposition rate, and these relationships showed more rapid slope in non-serpentine soil originated litter than that in serpentine soil.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.2 s.20
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• pp.39-47
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• 2002

For the purpose of data construction for the systematic management and sight-seeing guidance of the natural park, the Kumoh Mt. Province Park was selected as a pilot area. Digital topographic maps, thematic maps and satellite imagery covering the object area were processed and then landform analysis for elevation, slope, aspect and so on was conducted through DEM generation, and the landcover map and NDVI maP were extracted from Landsat TM data. The database was then constructed with these spatial data for GSIS. The image map was generated from IKONOS satellite data, which cover the pilot area data, with one meter resolution and also 3D visualization which was overlaid with main paths up a mountain were conducted. And the moving image files were produced along main paths up including main natural spectacular sights, cultural assets and management facilities. It is expected that the research result can be utilized as the fundamental data for re-assessing suitable land use and constructing Web-based guidance system.

• Journal of Korean Society of Forest Science
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• v.105 no.2
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• pp.157-166
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• 2016

This study was carried out to classify the current forest cover types and to propose the successional trends in the natural forest of Mt. Deogyu. The vegetation data were collected by the point-centered quarter method. The forest cover types were classified by various multivariate statistical analysis methods such as cluster analysis, indicator species analysis and multiple discriminant analysis. This forests were classified into five forest types by the species composition of upper layer and topographic positions: Quercus mongolica forest in the ridge, Fraxinus mandushurica-F. rhynchophylla-Cornus controversa forest and F. mandushurica forest in the valley, the Q. serrata - Pinus densiflora - Q. mongolica forest and P. densiflora forest in the low-slope. As a result of the forest successional trends depending on ecological and environmental characteristics in each forest type, the current forest types were expected that the forest succession would be proceeded toward Q. mongolica forest, F. mandshurica forest, mixed mesophytic forest, and oak-Carpinus laxiflora forest.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.444-451
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• 1987

The dependence of polarographic parameters on the pressure for the reduction of copper(II), cadmium(II), and zinc(II) complex ions with ethylenediamine, propylenediamine, and diethylenetriamine has been studied. In this study the dropping mercury electrode, the mercury pool electrode, and helix type of platinum wire were used as the working, the reference, and the auxilary electrode, respectively. With increasing the pressure from 1 atmosphere to 1,500 atmospheres, the reduction half-wave potentials of metal complex ions are shifted to the negative values and the diffusion currents become considerably larger, in keeping with the theory on the change of the physical properties of the electrolytic solution such as the density, the viscosity, the dielectric constant, and the electrical conductance, etc. The slope values of the logarithmic plot are increased with increasing the pressure, which indicates the more irreversible reduction. The temperature coefficients of diffusion current observed over the range of the temperature from 25$^{\circ}$C to 35$^{\circ}$C are about two percentage with increasing the pressure, therefore the polarographic reduction under the high pressure is controlled by diffusion. The linear relationships between diffusion current and concentration of metal complex ions are established over all pressure range.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1077-1086
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• 2013

Recent huge losses of both life and property have occurred by unexpected natural disasters. We studied snow damages, an important natural disaster issue because it happens more frequently in recent years. This study tries to select vulnerable areas of snowfall in advance and then establish climate change adaptation policy for minimizing unexpected snowfall damage. Busan, where is our study area, has hilly in downtown areas so that topography characteristics of the roads such as slope, elevation and aspect are vulnerable to snowfall. The sudden snowfall in Busan causes traffic jam and causes some schools in hilly to close some schools. At this moment, the adaptation policy has to be established for infrastructure (such as roads) in advance, because prediction of anomaly climate due to global warming is so difficult beside the damage of natural disaster is huge. Therefore, the purpose of this study is contribute to selecting and assessing vulnerable zones of snow damage focusing topography characteristics of the roads and then evaluating the degree of risk of vulnerable zones.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.4
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• pp.11-20
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• 2007

Most natural disasters in Korea are caused by meteorological natural phenomena, which include storms, heavy rains, heavy snow, hail, tidal waves, and earthquakes. Rainfall is the most frequent cause of disasters and accounts for about 80% of all disasters. Particularly in recent years, Korea has seen annual occurrences of natural disasters associated with landslides (slope and retaining wall collapse and burying) due to meteorological causes from the increasing intensity of heavy rains including local heavy rainfalls. In Korea, it is critical to analyze the characteristics of landslides according to rainfall characteristics and to take necessary and proper measures for them. This study assessed the possibility of landslides in the Gangwon region with a geographic information system by taking into account the inducer factors of landslides and the maximum continuous rainfall of each area. It also analyzed areas susceptible to landslides and checked the distribution of landslide-prone areas by considering the rainfall characteristics of those areas.

• Journal of Korea Water Resources Association
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• v.46 no.9
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• pp.957-967
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• 2013

High turbidity submersion due to torrential downpour is one of the factors that influences the plant growth. This study is focused on analyzing the plant's growth rate for Salix species such as gracilisyla, koreensis, glandulosa when these trees are waterlogged. The length of shoots for this control group in the natural state is 33.4% (gracilisyla), 24.3% (koreensis), 23.9% (glandulosa), however, they stopped growing in submersion. Compared to the leaf number of Salix species of this control group in the natural state, 144.5% (gracilisyla), 77.3% (koreensis), 40.3% (glandulosa) in the natural state 30 days, in 30 days submersion, the number of leaves is zero except koreensis. In the results of this experiment, Salix species stopped growing quickly when submersed. This study concludes that it is necessary to plant eco-friendly plants around the slope of the reservoir and dam where flooding takes place frequently.