• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6C
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• pp.219-229
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• 2010

Slope failure in South Korea generally occurs by the localized heavy rain in a rainy season and typhoon, and it annually causes huge losses of both life and property because nearly 70% of territory in South Korea is covered with mountains. It is required to measure the risk of slope failure quantitatively before proper prevention methods are provided. However, there is no way to estimate the risk based on realtime rainfall, geological characteristics, and geotechnical engineering properties. This study presents the development of digital terrion model to predict slope stability using infinite slope stability theory combined with temporal groundwater change. Case studies were performed to investigate factors to affect slope stability in Japan.

• Journal of Korea Water Resources Association
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• v.56 no.10
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• pp.603-617
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• 2023

This study aims to provide a better understanding of the turbulent flow characteristics in swash zone. A double dam-break method is employed to generate the swash zone flow. Comparing with the conventional single dam-break method, a delay between two gate opening can be controlled to reproduce various interactions between uprush and backwash. For numerical simulations, overInterDyMFoam based on OpenFOAM is adopted. Using overInterDyMFoam, interface between two immiscible fluids having different densities (i.e., air and water phases) can be tracked in a moving mesh with multiple layers. Two-dimensional Reynolds-Averaged Navier-Stokes equations are solved with a standard 𝜅-𝜖 turbulence model for momentum and continuity. Numerical model results are validated with laboratory experiment data for the time series of water depth and streamwise velocity. Turbulent kinetic energy distribution is further investigated to identify the turbulence evolution for each flow regime (i.e., uprush, backwash, and swash-swash interaction).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.737-746
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• 2019

Most landslides in the country are shallow failures triggered by intense rainfall. Many researchers have revealed the possibility of predicting shallow failure through the volumetric water content (VWC). This study examined how to determine shallow failure using the gradient characteristics of the volumetric water content. For this, flume experiments were conducted using weathered granite soil. To confirm the saturation state of the surface layer under a rainfall intensity of 30 and 50mm/hr, VWC sensors were installed at depths of 10 and 20 cm on the upper, middle and lower slope. The test results showed that a shallow failure determination using VWC could be applied limitedly according to the slope degree. In addition, the effective cumulative rainfall due to the rainfall infiltration velocity is considered the main factor for the failure time. The failure prediction using the gradient of the VWC depends on the installation location and depth of the sensor. According to the experimental data, the measured value at 20 cm below the slope was most effective. Therefore, an analysis method of VWC and the method of selecting the installation location confirmed through this study can provide important data for presenting the measurement criteria using VWC in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.249-256
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• 1986

The carp (Cyprinus carpio) used in the experiment were hatched in the spring this year and reared to 5.96g($4.84{\sim}6.55g$) in mean weight in a nursery pond at Daeyon fish farm, Pusan, Korea. The sample fish were exposed to different conditions of total ammonia (TA-N) concentrations 10, 20 and 30ppm and pH 6.5, 7.0, 7.5 and 8.0 at water temperatures 20, 25 and $30^{\circ}C$ for 24, 48 and 72 hours. After the procedure, the gill, liver and kidney of the fish were examined histopathologically. In this experiment, with the rise of water temperature, increase of pH and ammonia concentration, and the extension of exposure time the three organs showed the tendency of apparent abnormal changes such as hypertrophy and necrosis in their tissues. At $20^{\circ}C$ of water temperature gill tissue did not show any abnormality regardless of the change of pH at 10 ppm of ammonia concentration for 24 hours of exposure, but beyond the conditions given above, there occurred hypertrophy and the epithelium of gill lamellae was detached. The detach of gill lamellae epithelium initiated from the proximal part of the gill lamellae then gradually spread toward the uppermost tip. The heavier vacuolation of the liver was observed with the rise of water temperature and pH, and such morbid state in the liver was considered to be the result of edema in the liver tissue. The kidney showed no damage to the renal tubule epithelium at pH 6.5, but it was damaged at pH 8.0 when exposed to 30 ppm ammonia at $20^{\circ}C$ for 24 hours.

• Journal of Korea Water Resources Association
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• v.40 no.10
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• pp.833-840
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• 2007

The experimental study was carried out to investigate propagation distance of flood wave due to levee breach in a flat inundation area without obstacle. Hitter solution was considered to formulate the experimental results and a representative form was written referring to existing researches. As a result of experiments, it was found that the propagation velocity of the wave front in inundation area was significantly influenced by the initial water level in a channel, which was similar to flow in a channel due to dam break. An empirical formula was also suggested using the experimental results. The dimensionless propagation distance L can be written as the power function of dimensionless time T Coefficients k and m were varied with the dimensionless time T whereas k and m in Ritter solution were 2 and 0, respectively. The variation of coefficients in the relationship between L and T was influenced by the water depth in the inundation area and the fact proved that the changing points of L in the slope of relationship between L and T are the same to those of relationship between the dimensionless maximum water depth in the inundation area, $h_{max}$ and L.

• Applied Microscopy
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• v.38 no.3
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• pp.259-264
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• 2008

The stabilized $ClO_2$ gas has been used for many years by the food industry as a strong oxidizing and sanitizing agent that has broad and high biocidal effectiveness. Therefore, "stabilized $ClO_2$" gas may be used in fields of disinfectant and sterilization. But, there have been few studies on the decomposition-inhibition effect of stabilized $ClO_2$ gas with passage of time. The main purpose of this study was to examine the decomposition-inhibition effect of stabilized $ClO_2$ gas and the morphological change of kidney by measuring of the light and electron microscope. Sprague-Dawley (SD) rats weighting from 230 gm to 250 gm were used as experimental animals. Under ether anesthesia, the right kidney of rat was obtained. Put each sample in $37^{\circ}C$ and humidity $80{\pm}5%$ incubator, we obtained each sample after 0 day, 1 day, 2 days, 3 days, 4 days and 5 days. We proceeded the observation of light and electron microscope. The results obtained in this study reveal that stabilized $ClO_2$ gas is an effective decomposition inhibitor until 2 days that was conducted at $37^{\circ}C$ and humidity $80{\pm}5%$ conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.4
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• pp.452-458
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• 1997

Seed characteristics such as seed size, seed shape and cotyledon color are important in relation to processing and cooking of soybean. Seed shape, water absorption rate, and alkali digestibility were evaluated for 28 local black soybean collections. Water uptake rate was low in small seed size at low temperature(5, 2$0^{\circ}C$). However, higher water absorption rate was observed at high temperature(40, 6$0^{\circ}C$) regardless of seed size. When seeds soaked up water, it reached to water absorption equilibrium after 10 hrs below 2$0^{\circ}C$, within 10 hrs at 4$0^{\circ}C$, and around 4 hrs at 6$0^{\circ}C$, respectively. Significant positive correlations were observed between 100 seed weight and length, width and thickness of seed, respectively. Alkali digestibility value(ADV) was higher in large seed group than in small seed group. Among seed characteristics, significant positive correlation was shown between ADV and 100 seed weight, length, width, thickness and hilum length of seed, respectively. Soybean seed with green cotyledon showed higher ADV than that with yellow cotyledon.

• Nuclear Engineering and Technology
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• v.25 no.4
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• pp.539-547
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• 1993

A stochastic approach using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock media as a further extension for previous works［1-3］. Nuclide transport of decay chain of arbitrary length in the single planar fractured rock media in the vicinity of the radioactive waste repository is modeled using a continuous time Markov process. While most of analytical solutions for nuclide transport of decay chain deal with the limited length of decay chain, do not consider the case of having rock matrix diffusion, and have very complicated solution form, the present model offers rather a simplified solution in the form of expectance and its variance resulted from a stochastic modeling. As another deterministic way, even numerical models of decay chain transport, in most cases, show very complicated procedure to get the solution and large discrepancy for the exact solution as opposed to the stochastic model developed in this study. To demonstrate the use of the present model and to verify the model by comparing with the deterministic model, a specific illustration was made for the transport of a chain of three member in single fractured rock medium with constant groundwater flow rate in the fracture, which ignores the rock matrix diffusion and shows good capability to model the fractured media around the repository.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.181-187
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• 2011

In this paper, we proposed the vision-based efficient algorithm for road slide detection like as destruction of road cut slope. The proposed algorithm defines the image region as non surveillance and surveillance which is further divided by road, boundary and non road region. After that, it find the moving block, remember the history of movement using the TTL(Time To Live) table, determine the road slide by checking the existence of moving blocks from non road region to road region together. We confirmed the proposed algorithm detected the road slide effectively through experiments.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.365-374
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• 2003

This is a study on application of a TVD-Mccormack scheme for the computation of one-dimensional dam-break flows. The TVD scheme not only has the ability to damp out oscillations, but also does not contain terms with adjustable parameters. Moreover, the TVD-McCormack scheme does not cause any additional difficulty when dealing with the source term of the equation and retains second-order accuracy in both space and time. In this study, by appropriately designing the limiter functions, the TVD property can be achieved, and numerical oscillations near a jump discontinuities can be eliminated or reduced. Also, this numerical scheme has less computational errors when the direction of the predictor-corrector step is in the same direction as the shock wane propagation.