• Geomechanics and Engineering
• /
• v.17 no.2
• /
• pp.181-194
• /
• 2019

Due to the seepage of groundwater, the resisting force of slopes decreases and the sliding force increases, resulting in significantly reduced slope stability. The instability of most natural slopes is closely related to the influence of groundwater. Therefore, it is important to study slope stability under groundwater seepage conditions. Thus, using a simplified seepage model of groundwater combined with the analysis of stresses on the slip surface, the limit equilibrium (LE) analytical solutions for two- and three-dimensional slope stability under groundwater seepage are deduced in this work. Meanwhile, the general nonlinear Mohr-Coulomb (M-C) strength criterion is adopted to describe the shear failure of a slope. By comparing the results with the traditional LE methods on slope examples, the feasibility of the proposed method is verified. In contrast to traditional LE methods, the proposed method is more suitable for analyzing slope stability under complex conditions. In addition, to facilitate the optimization of drainage design in the slope, stability charts are drawn for slopes with different groundwater tables. Furthermore, the study concluded that: (1) when the hydraulic gradient of groundwater is small, the effect on slope stability is also small for a change in the groundwater table; and (2) compared with a slope without a groundwater table, a slope with a groundwater table has a larger failure range under groundwater seepage.

• Journal of Ecology and Environment
• /
• v.43 no.2
• /
• pp.161-182
• /
• 2019

Quantifying the amount of carbon pools in forest ecosystems enables to understand about various carbon pools in the forest ecosystem. Therefore, this study was conducted in the Chilimo dry afromontane forest to estimate the amount of carbon stored. The natural forest was stratified into three forest patches based on species composition, diversity, and structure. A total of 50 permanent sample plots of 20 m × 20 m (400 ㎡ ) each were established, laid out on transects of altitudinal gradients with a distance of 100 m between plots. The plots were measured twice in 2012 and 2017. Tree, deadwood, mineral soil, forest floor, and stump data were collected in the main plots, while shrubs, saplings, herbaceous plants, and seedling data were sampled inside subplots. Soil organic carbon (SOC %) was analyzed following Walkely, while Black's procedure and bulk density were estimated following the procedure of Blake (Methods of soil analysis, 1965). Aboveground biomass was calculated using the equation of Chave et al. (Glob Chang Biol_20:3177-3190, 2014). Data analysis was made using RStudio software. To analyze equality of means, we used ANOVA for multiple comparisons among elevation classes at α = 0.05. The aboveground carbon of the natural forest ranged from 148.30 ± 115.02 for high altitude to 100.14 ± 39.93 for middle altitude, was highest at 151.35 ± 108.98 t C ha^-1 for gentle slope, and was lowest at 88.01 ± 49.72 t C ha^-1 for middle slope. The mean stump carbon density 2.33 ± 1.64 t C ha^-1 was the highest for the middle slope, and 1.68 ± 1.21 t C ha^-1 was the lowest for the steep slope range. The highest 1.44 ± 2.21 t C ha^-1 deadwood carbon density was found under the middle slope range, and the lowest 0.21 ± 0.20 t C ha^-1 was found under the lowest slope range. The SOCD up to 1 m depth was highest at 295.96 ± 80.45 t C ha^-1 under the middle altitudinal gradient; however, it was lowest at 206.40 ± 65.59 t C ha^-1 under the lower altitudinal gradient. The mean ecosystem carbon stock density of the sampled plots in natural forests ranged from 221.89 to 819.44 t C ha^-1. There was a temporal variation in carbon pools along environmental and social factors. The highest carbon pool was contributed by SOC. We recommend forest carbon-related awareness creation for local people, and promotion of the local knowledge can be regarded as a possible option for sustainable forest management.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.6
• /
• pp.59-66
• /
• 2012

The purpose of this study is to estimate the behavior and the mechanism of debris flow on the slope, which has specially various gradient plane. The numerical simulation was performed by using the Finite Differential Element method (FDM) based on the equation for the mass conservation and momentum conservation. The mechanism of flow type for debris flow is divided into three flow types which are stony debris flow, immature debris flow, and turbulent water flow, respectively. First, flow discharge, water flow depth, sediment volume concentration was investigated by variable input of flow discharge at the straight slope angle and two step inclined plane. As the input of flow discharge was decrease, flow discharge and water flow depth was increased, after the first coming debris flow only reached at the downstream. As the input of flow discharge was increased, the curve of flow discharge and flow depth was highly fluctuated. As the results of RMS ratio, the flow discharge and flow depth was lower two step slope angle than the straight slope angle. Second, the behavior of debris flow was investigated by the four cases of gradient degree at the downstream of slope angle. The band width of flow discharge and flow depth for $14^{\circ}$ between $16^{\circ}$ was higher than other gradient degree, and fluctuation curve was continuously high after 10 seconds.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.6 no.1
• /
• pp.31-36
• /
• 2001

Optimal operation in chromatography is needed to save operation time and the solvent used in multiple chromatographic runs. To this end, many simulation studies of chromatography process have been performed. The relationship between the distribution coefficient and the ionic strength is important in gradient elution ion chromatography. Experimental runs and computer simulations were carried out under linear gradient elution condition in order to compare the experiments and the simulation. Experiments were performed with formic acid under isocratic conditions to determine the simulation equation parameters. Computer simulation was based on three equations which related distribution with ionic strength as follows; K=${\alpha}$I(sup)-${\beta}$, K=A+BI+Cl$^2$and K=y(sub)0+A$_1$$.$e(sup)(-I/m$_1$). The effects of gradient slope on the chromatograms are discussed, and good agreement between the experimental and the simulated results is shown.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.501-508
• /
• 2002

The percentage of a mountainous district in our country is comparatively high but the concern for rock mass has been disregarded for a long time. Especially for rock slope, the most important factors are geometric characteristics and their shear strength parameter. In this paper, parametric studies are performed using the distinct element computer program UDEC-BB for rock slopes. Parameters adopted in this paper are joint angle, spacing, persistence, aperture and shear strength parameters (JRC, JCS, basic friction angle). To estimate slope stability, shear strength reduction method is used. The most important factors affecting rock slope stability are joint angle and spacing. The relationship between average displacement calculated by UDEC-BB and safe factor by shear strength reduction method is researched.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.20 no.3
• /
• pp.33-43
• /
• 1992

The perceptual characteristic on the slope scenery around highway is very similar as the general perceptual characteristic in the landscape. This process determines by the relationship between the scenery observers and the characteristics of its place. It is very important to have a analysis on highway slope scenery in our particular culture in Korea since our country's highways are done by cutting mountains : therefore, we have a lot of slopes around highways. The physical characteristics on the highway scenery determines how we should build scenery around highway to a satisfactory level. The results drawn from this research work are as follow: 1) The satisfaction for slope scene had been affected by sex, native and experience of travel. I thought that the slope scene having peculiar form will offer the highest satisfaction. 2) Psychological factor, reflected satisfaction of slope scene, 몽 a grip of three factors as the factor of evaluation, texture, formation, and presumption formula is : Satisfaction=1.04(Evauluation factor)+0.83(Texture factor)+0.15(Formation factor)+4.28)R2=0.69). 3) Vine among the vegetation componeents of slope scene highly correlated with the evaluation factor and grass, shrub correlated with the texture factor. 4) Rock among the structual components of slope scene highly correlated with the formation factor, and stockade, lattice correlated with the evalution factor. 5) Gradient among the properties which determined slope form, highly correlated with the formation factor.

• Journal of Astronomy and Space Sciences
• /
• v.16 no.1
• /
• pp.1-10
• /
• 1999

The archival long-slit spectra, covering the wavelength range 4050 ~ 5150 $\AA$, have been used to investigate the radial behavior of absorption line fea-tures (G4300, Fe4383, Ca4455, Fe4531, and $H{\beta}$) of an elliptical galaxy NGC 5846A. The heliocentric recession velocity of NGC 5846 has been derived as $1949{\pm}87\;kms^{-1}$. Fe absorption lines of NGC 5846A show significant radial gradients with the mean slope of $\Delta/Delta(r")=-0.863\pm0.202$. There is also a significant radial gradient of G band with a slope of $-1.109{\pm}0.098$. On the other hand, no radial gradients has been detected on the Ca4455 and $H{\beta}$ absorptions of NGC 5846A. A metallicity gradient, which is derived from the Fe line gradients, is similar to the abundance gradient predicted by Larson's (1975) dissipative models for the formation of elliptical galaxies. We also note that a galaxy-galaxy interaction could affect the line gradients of NGC 5864A.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.27 no.2
• /
• pp.41-50
• /
• 1999

The purpose of this study is to find out the changes in geomorphic characteristics of a small watershed when a golf course is constructed. The research site is a set of seven small watersheds including an 18-hole golf course that were randomly selected. The size, shape, and drainage network of watersheds were measured by using planimeter, watershed eccentricity, and stream order, respectively. In addition, a 25m$\times$25m mesh was used on topographic maps and grading plans in order to obtain the slope, elevation, and aspect of the watersheds. The major results of this research, while investigating of the changes in geomorphic characteristics of watersheds when a golf course is constructed, are as follows: 1. The size of watersheds is increased in accordance to the difference in elevation between the golf course site and the small watershed. 2. The watershed eccentricities are in general similar except for a few low-valued cases. 3. The changes in the average altitude and the gradient are more drastic with their bigger original values. 4. The aspects are changed more with decreasing elevation. 5. The stream order decreases in the case of a low watershed eccentricity. 6. The surface modification has a closer relationship to the slope rather than the size of effective use area. 7. With a steeper gradient and an excessively low gradient, the height of cutting/filling is increased.

• Ocean and Polar Research
• /
• v.27 no.3
• /
• pp.277-288
• /
• 2005

Spatial distribution and vertical structures of water masses around the Antarctic continental margin are described using synthesized hydrographic data. Antarctic Surface Water (AASW) over the shelf regime is distinguished from underlying other water masses by the cut-off salinity, varying from approximately 34.35 to 34.45 around Antarctica. Shelf water, characterized by salinity greater than the cut-off salinity and potential temperature less than $-17^{\circ}C$, is observed on the Ross Sea, off George V Land, off Wilkes Land, the Amery Basin, and the Weddell Sea, but in some shelves AASW occupies the entire shelf. Lower Circumpolar Deep Water is present everywhere around the Antarctic oceanic regime and in some places it mixes with Shelf Water, producing Antarctic Slope Front Water (ASFW). ASFW, characterized by potential temperature less than about $0^{\circ}C$ and greater than $-17^{\circ}C$, and salinity greater than the cut-off salinity, is found everywhere around Antarctica except in the Bellingshausen-Amundsen sector. The presence of different water masses over the Antarctic shelves and shelf edges produces mainly three types of water mass stratifications: no significant meridional property gradient in the Bellingshausen and Amundsen Seas, single property gradient where ASFW presents, and a V-shaped front where Shelf Water exists.

• The Korean Journal of Physiology
• /
• v.17 no.2
• /
• pp.119-124
• /
• 1983

The in vivo and in vitro buffer capacities of true plasma and tissue buffer capaciies were compared on dogs. Intracellular pH was determined on skeletal muscle by a modification of the method of Schloerb and Grantham using $C^{14}$ DMO. The in vivo curve for plasma or extracellular fluid has a much lower slope than the in vitro curve. The in vivo slope of skeletal muscle in the dog is approximately 20 sl. The slope for skeletal muscle in vivo falls between the in vitro and in vivo slopes of true plasma. It appears that intracellular hydrogen ion varies linearly with extracellular hydrogen ion when $CO_2$ tension is changed. Both hydrogen ion gradient and Hi/He ratio vary in skeletal muscle, with an increase in $CO_2$ tension. Infusion of 0.3N HCl gave two distinct patterns, the $H_i-H_e$ gradient decreased; and it would appear that very little hydrogen ion as such penetrated to the inside of the cells during the time of observation. Although lactic acid presumably enters the cell and the same of larger load was given as was used for hydrochloric acid, only very mild intracellular acidosis resulted, ostensibly due to metabolism of this substrate. Gluconic acid produced a more severe acidosis, both intracellularly and extracellularly, but with both of these acids the hydrogen ion gradient decreased and the $H_i/H_e$ ratio also decreased. The experiments on the dogs with hemorrhagic shock the hydrogen ion increase producing the acidosis originates inside the cells. Even so, the hydrogen ion gradient increased only very slightly in the acute experiments. This may suggest that even over short intervals of time skeletal muscle cells have a capacity to pump out hydrogen ions at a rate which maintains approximately the normal $H_i/H_e$ gradient when the source of the hydrogen ion is in the interior of the cell.