• Journal of computational fluids engineering
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• v.19 no.4
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• pp.52-60
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• 2014

Recently, coastal structures have been built to protect coastal areas. However, if a tidal wave caused by an earthquake hits the coast, it would cause catastrophic damages. It is important to analyze the basics and the characteristics of a tsunami to reduce damages caused by natural disasters. In this study, a tsunami passing over different topographical changes is simulated with VOF method based on FVM(Finite Volume Method). The reduction of both scale and velocity is accomplished by similarity analysis, and an initial energy is generated by increasing the water level as needed to create a tsunami as if it is caused by a crustal movement. It is found that the present method is appropriate to simulate the tsunami with its mechanism.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.159-167
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• 2015

Low-level outlets are necessary to empty reservoir storage in case of emergency such as abrupt storage level rise due to storm, dam body inspection as well as initial reservoir storage filling. However, the Korean standard for low-level outlet should be complemented. In this study, the HEC-ResSim model is utilized to simulate and calculate the capacity of the outlets and the days of release in order to evacuate reservoir storage safely. Three cases are analyzed according to its capacity. As a large dam with more than $1,000{\times}106m^3$ total capacity, Soyanggang Dam is selected and as a medium dam between $100{\times}106m^3$ and $1,000{\times}106m^3$ total capacity, Habcheon Dam is selected. Finally as a small dam with a total capacity less than $100{\times}106m^3$, Daegok Dam is selected. The size of low-level outlet and days of storage evacuation is estimated and the applicability of the analysis method is studied.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.823-827
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• 2005

Fusarium mycotoxin deoxynivalenol (DON) contents and its critical quality parameters were analyzed using two-rowed, six-rowed, and hulless barleys. DON content in the two-rowed Korean barleys was lower than that in the six-rowed barleys. The average DON contents of six-rowed, two-rowed, and hulless barleys were 1.35 ppm, 0.36 ppm, and 0.49 ppm, respectively. The DON content was reduced by 6.2% by sieving, by 6.0% by washing with water and by 18.1-69.8% by treatment with aqueous chemical solutions. Of the reagents investigated, aqueous sodium bicarbonate gave the greatest reduction in the barley DON level. The DON content was reduced to 62.5% of initial level after 3 days of steeping and to 23.1% after 3 days of germination. DON was not detected after steeping barley for 24 hr in 0.1M $Na_2CO_3$ solution with 0.1 % activated carbon.

• Journal of Medicine and Life Science
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• v.18 no.2
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• pp.31-34
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• 2021

The pharmacokinetic properties of transdermal nicotine patches (TNPs) are different from those of other routes of nicotine administration; further, acute nicotine poisoning by TNPs may present with different clinical features. In the present report, we describe the case of a 23-year-old woman who was admitted to emergency department (ED) at Jeju National University Hospital with loss of consciousness. Five hours before the ED visit, she used multiple TNPs to attempt suicide. Initially, nausea and vomiting occurred, and the symptoms worsened over time. We immediately removed the TNPs, and the application sites were gently washed with sterile water. The patient's level of consciousness gradually improved, and she fully recovered an altered mental status 5 hours later. Her initial urinary cotinine level was 324 ng/mL. Physicians should be aware that acute nicotine poisoning by TNPs can cause various toxic symptoms.

• Journal of the Korean GEO-environmental Society
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• v.2 no.1
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• pp.57-65
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• 2001

In this study, the seepage behavior and the stability of the extension embankment were estimated for three cases the permeability coefficient of an extension part and the rising velocity due to the rainfall of flood period. In parallel flow condition, the unstability of the slope due to embankment erosion was examined by analyzing the variation of seepage line by the seepage modeling tests and FEM analysis, and the stability of the embankment slope accompanied by the sudden rise of the water level after the flood. The seepage behavior of extension embankment indicates that the larger permeability of the extension part the longer initial seepage distance, and the exit point from embankment slope is gradually increased, and then shows unstable seepage behavior that occurs a partial collapse as safety factor decreases with time. It is because of the increment of exit points due to variation of seepage line and rising velocities of water level. Also, the collapse aspect of embankment slope shows that the increment rising velocities of water level causes the increment collapse height and depth.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.5
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• pp.1-11
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• 2010

It is very difficult to control the expansion of reed at a wetland ecological park due to their aggressive reproduction capability. Therefore, proper topography and wetland hydrology should be provided before the construction of a wetland ecological park. Appropriate measures should be taken at the initial stages to prevent reed expansion. Field experiments were conducted at the newly constructed wetland ecological park for 15 months to develop methods to control the reproduction and expansion of Phragmites communis. A complete shading method had the best effect on the prevention of reed reoccurrence among other methods. Complete removal of the rhizomes controlled the reed growth to a greater extent than cutting the aboveground shoots. Water-level manipulation was also better than a half-shading method for the prevention of reed reproduction. These results indicated that soil properties and edge effects can influence the reed growth. Cutting only the aboveground shoots facilitates the growth of reed. These results suggest that reed control should be implemented repeatedly and an alteration in the wetland topography and hydrology may be more effective in the long term. Combination of treatments such as water-level management with shading should be considered to control the growth of reed. Adoptive management for created or restored ecosystem might be considered for accomplishment of its original purpose.

• Environmental Engineering Research
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• v.14 no.4
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• pp.244-249
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• 2009

Designing an ozone contactor is complicated because the residual ozone, log C. parvum inactivation, and bromate formation should be optimized with fluctuating water quality. OCM software was developed to assist a plant designer or an operator to fulfill the sophisticated optimization required in the design or operation of a new or an existing plant. In this article, numerical simulations were carried out using the OCM software for the design of a new ozone contactor under diverse design factors (i.e., three pHs, three temperatures, low and high dispersion numbers, and four and ten cells with complete mixing) with kinetic parameters obtained from the sand-filter effluent of a water treatment plant treating water from the Paldang impoundment. The results of the simulation suggested that a high residual ozone concentration at low pH and low temperature would be challenging, and PFR-like hydrodynamics could lower the residual ozone concentration. The inactivation of C. parvum oocysts increased at a lower pH. A lower dispersion number and more cell division increased the inactivation efficiency. Bromate was instantaneously formed during the initial ozonation stage. The effluent concentration was much lower than the regulatory levels imposed by the USEPA because of the low bromide level in raw water.

• Elastomers and Composites
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• v.48 no.3
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• pp.181-189
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• 2013

Unfilled, carbon black-filled, and silica-filled natural rubber (NR) composites were aged with a circular deformation at $60-90^{\circ}C$ and the recovery behaviors were investigated. The samples were aged under the altering aging medium systems of air and distilled water every day for 10 days. The order of the recoveries according to the filler systems was unfilled > silica > carbon black. The recoveries of the samples aged in the air to water altering system were greater than those of the samples aged in the water to air altering system. The initial aging medium dominantly influenced the deformation level.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.682-689
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• 2010

The purpose of this study was to determine any detrimental effects on surrounding environments by using bottom ash, waste tire, and mixture as a fill material to raise the ground level. Three different initial pHs (4, 6, 8) were applied to bottom ash and initial pH of 4 was used to waste tire and mixture. Among 7 heavy metals, Pb and Zn were exceeded drinking water standards but their concentrations decreased below drinking water standards within 1 PVE. Among 5 anions, sulfate exceeded 10 times of drinking water standards and further higher partition coefficients resulted in increased PVE of 8.21. For the mixture of bottom ash and waste tire, its concentrations of heavy metals and anions were decreased due to the dilution effect and lowered PVE from 8.21 (BA) to 5.89.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.903-911
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• 2022

Groundwater, one of the resources for supplying water, fluctuates in water level due to various natural factors. Recently, research has been conducted to predict fluctuations in groundwater levels using Artificial Neural Network (ANN). Previously, among operators in ANN, Gradient Descent (GD)-based Optimizers were used as Optimizer that affect learning. GD-based Optimizers have disadvantages of initial correlation dependence and absence of solution comparison and storage structure. This study developed Gradient Descent combined with Harmony Search (GDHS), a new Optimizer that combined GD and Harmony Search (HS) to improve the shortcomings of GD-based Optimizers. To evaluate the performance of GDHS, groundwater level at Icheon Yullhyeon observation station were learned and predicted using Multi Layer Perceptron (MLP). Mean Squared Error (MSE) and Mean Absolute Error (MAE) were used to compare the performance of MLP using GD and GDHS. Comparing the learning results, GDHS had lower maximum, minimum, average and Standard Deviation (SD) of MSE than GD. Comparing the prediction results, GDHS was evaluated to have a lower error in all of the evaluation index than GD.