• Journal of Marine Life Science
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• v.3 no.2
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• pp.51-58
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• 2018

Variations in water temperature are known to affect almost every part of fish physiology. The rise in water temperature due to climate change can physically damage fish. This study was conducted to evaluate the health status of the Atlantic salmon (Salmo salar) at high water temperature (20℃) than the optimum water temperature (15℃). Liver tissue exerts important metabolic functions in thermal adaptation. Therefore, liver tissue was used in this study. The evaluation method is to develop the biomarker gene using NGS RNAseq analysis and to examine the expression pattern using RT-qPCR analysis. The NGS RNAseq analysis revealed 1,366 differentially expressed genes, among which 880 genes were increase expressed and 486 genes were decrease expressed. The biomarker genes are such as heat shock protein 90 alpha (Hsp90α), heat shock protein 90 beta (Hsp90β) and cytochrome P450 1A (CYP1A). The selected genes are sensitive to changes in water temperature through NGS RNAseq analysis. Expression patterns of these genes through RT-qPCR were similar to those of NGS RNAseq analysis. The results of this study can be applied to other fish species and it is considered to be useful industrially.

• Tunnel and Underground Space
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• v.22 no.1
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• pp.69-76
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• 2012

Theoretical backgrounds on the experimental methods of explosive welding, explosive forming and shock consolidation of powders are introduced. Explosive welding experiments of titanium (Ti) and stainless steel (SUS 304) plate were carried out. It was revealed that a series of waves of metal jet are generated in the contact surface between both materials; and that the optimal collision velocity and collision angle is about 2,100~2,800 m/s and $15{\sim}20^{\circ}$, respectively. Also, explosive forming experiments of Al plate were performed and compared to a conventional press forming method. The results confirmed that the shock-loaded Al plate has a larger curvature deformation than those made using conventional press forming. For shock consolidation of powders, the propagation behaviors of a detonation wave and underwater shock wave generated by explosion of an explosive are investigated by means of numerical calculation. The results revealed that the generation and convergence of reflected waves occur at the wall and center position of water column, and also the peak pressure of the converged reflected waves was 20 GPa which exceeds the detonation pressure. As results from the consolidation experiments of metal/ceramic powders ($Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$), shock-consolidated $Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$ bulk without cracks was successfully obtained by adapting the suggested water container and strong bonding between powder particles was confirmed through microscopic observations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4B
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• pp.339-346
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• 2009

In this study, the flow characteristics of the sea region, where tidal current and shock waves are combined, are identified using a three-dimensional numerical model (Princeton Ocean Model, POM). The model is adopted and applied for simulating the flows of the sea region near the open sections during the seadike closure work of Sihwa Seadike which was closed in 1994. The simulation results show that the shock waves with high velocities propagate through the sections toward the inside and outside of the seadike during the periods of the spring and ebb tides, respectively. It is found that the phenomena of flow separation occur near the shock waves; as the shock waves extend to wider zones after passing the sections, their effects on the tidal current become weak. In addition, the longitudinal velocity profiles of the flows are revealed to be affected by the shock waves. For all the simulations, at the ebb tide, the drawdown of the water levels occurs in front of the open section, respectively, especially, hydraulic jump occurs when simulating the case of maximum difference in water level between the inside and outside of the seadike. As a result, it is thought that the flow characteristics of the sea region dominated by shock waves need to be identified employing three-dimensional analysis approach, which is expected to provide the information for ocean engineering works and facility management.

• Journal of the Korean Society of Safety
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• v.21 no.6 s.78
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• pp.26-32
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• 2006

The paper considers the electrical shock risk of the human body due to underwater leakage current in electric field. The characteristics of electric shock in fresh water due to the leakage of submerged electric facility in the bathtub in public baths were conducted. The exposed live electrode is modeled as a point source of electric current source. It is assumed that divergent monopole field exists in the vicinity of the current source, regardless of the presence of return electrode and insulating boundary. The electric potentials in the steel bathtub, Diesen and Mole and Flux3D program one are measured according to the distance from leakage source. The results show that the increased shock risk and safe distance are estimated by the bathtub of limited width and the voltage calculated on the basis of a divergent monopole field concept is compared with the measured value.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.167.1-167
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• 2003

To maintain high quality and to extend the shelf life of intact and minimally processed apple cubes, the effect of heat shock on the texture and color of apple cubes (Fuji) was evaluated in this study. After peeled and cored, the apples were cut into cubes of 1.5 cm. The heat shock was immersion in heated water from 25$^{\circ}C$ to 95$^{\circ}C$ in 10$^{\circ}C$ increments for 2 min and cooling to storage temperature as soon as possible after heat treatment. The effect of heat treatment in terms of color and texture measurements with respect to time was investigated, respectively during 7 days storage at in LDPE film bags without sealing at 4$^{\circ}C$, and 95% relative humidity air. Results suggest that heat shock (55$^{\circ}C$, 2 min) may have effectively delayed browning, and there were significant changes in color of apple cube when the temperature of heat shock is above 75$^{\circ}C$. And hardness, stiffness and firmness, which were used to describe texture, behaved similarly in the textural qualities. It was shown that the texture of the apple cubes was decreased with temperature increase. The value of them were most decreased to 70% of the initial ones after treated with 85$^{\circ}C$ and 95$^{\circ}C$ on the lust day.

• Journal of the Korean Professional Engineers Association
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• v.45 no.2
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• pp.44-47
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• 2012

The water is very important resource that we can maintain our life and get the high-quality energy. The water begins with creation of the earth and circulates in the atmosphere, ocean, surface and subsurface in the form gases, liquids and solids. Human has used the water in abundance, however we have polluted water irresponsibly and discharged wastewater into the earth. We must think, how long does areas, pollution, pollution treatment, produce. Consider together about the water shock will occur when in any form.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.575-584
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• 2021

The critical low temperature and response of the behavioral tolerance of red sea bream Pagrus major fingerlings were determined using the continuous behavior monitoring system (CBMS). The behavior of the experimental organisms was observed by decreasing the water temperature by 2.0℃ and 4.0℃ every 12 hours and 24 hours in the range of 8.0-20.0℃. An unstable behavior pattern was observed in red seabream fingerlings exposed to water temperatures below 12.0℃, in which the swimming activity decreased and repeatedly stopped, regardless of the exposure time and water temperature fluctuation. The swimming ability of the organisms exposed to 8.0-10.0℃ decreased sharply, and the behavior of staying at the bottom of the test tank was observed. Only 50 % of the organisms survived due to the low-temperature stress, and all individuals died within six hours after the cold shock. In addition, the behavior index (BI) decreased rapidly, and the amplitude change of the coefficient of variation (CV) was found to have a greater variation than the other water temperatures (p<0.05). Low-temperature stress of red sea bream is promoted at 12.0℃, and it is interpreted as the tolerance limit, which can induce a sublethal response of the organisms exposed to cold shock of 8.0-10.0℃.

• Korean Journal of Ecology and Environment
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• v.53 no.4
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• pp.324-330
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• 2020

Ozone (O₃) is a general disinfectant to remove micro-pollutants in water treatment system. Previous studies have reported effect of ozone to bacteria and pathogens removal, but its effect to the relatively large organisms has little known. In this study, we investigated potential effects of ozone toxicity to the non-bite midge larvae (Glyptotendipes tokunagai) with accumulate mortality, coloration change and expression of heat shock protein 70 (HSP70). The accumulate mortality rate of G. tokunagai increased in a dose-time dependent manner and the highest mortality rate was observed to 75% at 30 minute of exposure duration with 2.0 ppm of ozone concentration. Exposure to ozone was a factor increasing body color of the larvae. The tendency of HSP70 mRNA expression showed up-regulation in ozone exposure at 20 minute. After that time, the expression of HSP70 in exposed group decreased to a similar level of control group. Our results clearly showed that ozone toxicity affects physical and molecular activity of G. tokunagai, implying the potential hazardous of ozone in the aquatic ecosystem including macroinvertebrates.

• Explosives and Blasting
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• v.35 no.3
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• pp.21-30
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• 2017

When explosives explode in water, the effect of post-explosion gas after explosion should be considered, unlike explosion in the air. During explosion in water, the propagation velocity of the explosion pressure is faster than when the explosion occurs in the air. The generated gas is diffused and trapped in the form of bubbles by water before the energy is dissipated. At this time, the bubble expands and contracts, creating a shock wave. In order to investigate this series of phenomena, a cylinder type steel water tank capable of observing the interior was fabricated and explosion experiments were conducted. In this study, a small amount of shell-free pentolite was exploded in water. Experiments were performed to observe the behavior of the generated gas bubble as well as to measure the shock wave generated. We designed the experimental method of underwater explosion and examined the results.

• Journal of Korea Water Resources Association
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• v.44 no.6
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• pp.461-470
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• 2011

Abrupt and gradual levee breach analyses on the flat domain were implemented by laboratory experiments and numerical simulations. To avoid the reflective wave from the side wall the experiment was performed in a large domain surrounded by waterway. A numerical model was developed for solving the two-dimensional gradual levee breach flow. The results of the numerical simulation developed in this study showed good agreement with those of the experimental data. However, even if the numerical schemes effectively replicated the trends of the observed water depth for the first shock, there were little differences for the second shock. In addition, even though the model considered the Smagorinsky horizontal eddy viscosity, the location and height of the hydraulic jump in the numerical simulation were not fairly well agree with experimental measurements. This shows the shallow water equation solver has a limitation which does not exactly reproduce the energy dissipation from the hydraulic jump. Further study might be required, considering the energy dissipation due to the hydraulic jump or transition flow from reflective wave.