• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.627-635
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• 2019

A programmable drone is a drone developed not only to experience the basic principles of flight but also to control drones through Arduino-based programming. Due to the nature of the training drones, the main users are students who are inexperienced in controlling the drones, which often cause frequent collisions with external objects, resulting in high damage to the drones' frame. In this study, the structural stability of the drone was evaluated by means of a structural dynamics based collision simulation for educational drone frame. Collision simulations were performed on three cases according to the impact angle of $0^{\circ}$, $+15^{\circ}$ and $-15^{\circ}$, using an analytical model with approximately 240,000 tetrahedron elements. Using ANSYS LS-DYNA, which provides excellent functions for the simulation of the dynamic behavior of three-dimensional structures, the stress distribution and strain generated on the drone upper, the drone lower, and the ring assembly were analyzed when the drones collided against the wall at a rate of 4 m/s. Safety factors resulting from the equivalent stress and the yield strain were calculated in the range of 0.72 to 2.64 and 1.72 to 26.67, respectively. To ensure structural stability for areas where stress exceeds yield strain and ultimate strain according to material properties, the design reinforcement is presented.

• Biomolecules & Therapeutics
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• v.29 no.6
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• pp.685-696
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• 2021

In this study, we investigated the inhibitory effect of 5-aminolevulinic acid (ALA), a heme precursor, on inflammatory and oxidative stress activated by lipopolysaccharide (LPS) in RAW 264.7 macrophages by estimating nitric oxide (NO), prostaglandin E2 (PGE2), cytokines, and reactive oxygen species (ROS). We also evaluated the molecular mechanisms through analysis of the expression of their regulatory genes, and further evaluated the anti-inflammatory and antioxidant efficacy of ALA against LPS in the zebrafish model. Our results indicated that ALA treatment significantly attenuated the LPS-induced release of pro-inflammatory mediators including NO and PGE2, which was associated with decreased inducible NO synthase and cyclooxygenase-2 expression. ALA also inhibited the LPS-induced expression of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, reducing their extracellular secretion. Additionally, ALA abolished ROS generation, improved the mitochondrial mass, and enhanced the expression of heme oxygenase-1 (HO-1) and the activation of nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) in LPS-stimulated RAW 264.7 macrophages. However, zinc protoporphyrin, a specific inhibitor of HO-1, reversed the ALA-mediated inhibition of pro-inflammatory cytokines production and activation of mitochondrial function in LPS-treated RAW 264.7 macrophages. Furthermore, ALA significantly abolished the expression of LPS-induced pro-inflammatory mediators and cytokines, and showed strong protective effects against NO and ROS production in zebrafish larvae. In conclusion, our findings suggest that ALA exerts LPS-induced anti-inflammatory and antioxidant effects by upregulating the Nrf2/HO-1 signaling pathway, and that ALA can be a potential functional agent to prevent inflammatory and oxidative damage.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.25-38
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• 2021

Purpose: To reduce the damage caused by continuously occurring typhoons, we proposed a standardized grid so that it could be actively utilized in the prevention and preparation stage of typhoon response. We established grid-based convergence information on the typhoon risk area so that we showed the effectiveness of information used in disaster response. Method: To generate convergent information on typhoon hazard areas that can be useful in responding to typhoon situation, we used various types of data such as vector and raster to establish typhoon hazard area small grid-based information. A standardized grid model was applied for compatibility with already produced information and for compatibility of grid information generated by each local government. Result: By applying the grid system of National branch license plates, a grid of typhoon risk areas in Seoul was constructed that can be usefully used when responding to typhoon situations. The grid system of National branch license plates defines the grid size of a multi-dimensional hierarchical structure. And a grid of typhoon risk areas in Seoul was constructed using grids of 100m and 1,000m. Conclusion: Using real-time 5km resolution grid based weather information provided by Korea Meteorological Administration, in the future, it is possible to derive near-future typhoon hazard areas according to typhoon travel route prediction. In addition, the national branch number grid system can be expanded to global grid systems for global response to various disasters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.5
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• pp.187-194
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• 2021

The damage caused by typhoons is gradually increasing due to the climate change recently. Hence, many studies have been conducted over a long period of time on various factors that determine the characteristics of storm surge, and most of relationships have been discovered. Because storm surge is complexly determined by various factors, it often show different results and draw different conclusions. For this reason, this study was conducted to understand the various characteristics of storm surge caused by changes in the forward speed of typhoons. This study was carried out with a numerical model, and the effect of forward speed could be analyzed by simplifying other factors as much as possible. When forward speed is increased, storm surges caused by typhoons tended to increase gradually. The storm surge showed a wide and gentle increase at a slow speed, but a narrow and steep one at a fast speed. In the case of the same forward speed, it was found that the storm surge was significantly influenced by the water depth of actual sea area. It was confirmed that the change in forward speed after passing Jeju Island did not significant affect on the storm surge in the south coast of Korea.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.6
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• pp.37-47
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• 2005

Recently, the malicious e-mail worm-viruses have been widely spreaded over the Internet. If the recipient opens the e-mail attachment or an e-mail itself that contains the worm-virus, the worm-virus can be activated and then cause a tremendous damage to the system by propagating itself to everyone on the mailing list in the user's e-mail package. In this paper, we have designed and implemented two methods blocking e-mail worm-viruses. In the fist method, each e-mail is transmitted only by sender activity such as the click of button on a mail client application. In the second one, we insert the two modules into the sender side, where the one module transforms a recipient's address depending on a predefined rule only in time of pushing button and the other converts the address reversely with the former module whenever an e-mail is sent. The lader method also supports a polymorphism model in order to cope with the new types of e-mail worm-virus attacks. The two methods are designed not to work for the e-mail viruses. There is no additional fraction on the receiver's side of the e-mail system. Experimental results show that the proposed methods can screen the e-mail worm-viruses efficiently with a low overhead.

• Journal of Life Science
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• v.31 no.5
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• pp.527-535
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• 2021

Lysosomes are organelles surrounded by membranes that contain acid hydrolases; they degrade proteins, macromolecules, and lipids. According to nutrient conditions, lysosomes act as signaling hubs that regulate intracellular signaling pathways and are involved in the homeostasis of cells. Therefore, the lysosomal dysfunction occurs in various diseases, such as lysosomal storage disease, neurodegenerative diseases, and cancers. Multiple forms of stress can increase lysosomal membrane permeabilization (LMP), resulting in the induction of lysosome-mediated cell death through the release of lysosomal enzymes, including cathepsin, into the cytosol. Here we review the molecular mechanisms of LMP-mediated cell death and the enhancement of sensitivity to anticancer drugs. Induction of partial LMP increases apoptosis by releasing some cathepsins, whereas massive LMP and rupture induce non-apoptotic cell death through release of many cathepsins and generation of ROS and iron. Cancer cells have many drug-accumulating lysosomes that are more resistant to lysosome-sequestered drugs, suggesting a model of drug-induced lysosome-mediated chemoresistance. Lysosomal sequestration of hydrophobic weak base anticancer drugs can have a significant impact on their subcellular distribution. Lysosome membrane damage by LMP can overcome resistance to anticancer drugs by freeing captured hydrophobic weak base drugs from lysosomes. Therefore, LMP inducers or lysosomotropic agents can regulate lysosomal integrity and are novel strategies for cancer therapy.

• Smart Media Journal
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• v.9 no.4
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• pp.81-90
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• 2020

Due to the recent economic development and the improvement of income level in China, the desire for quality medical services is increasing compared to the past. As an alternative to satisfy these needs, various applications using smart phones and the like are being developed. The new corona that occurred in December 2019 began to show great interest in non-face-to-face telemedicine services using smart phones due to the worldwide spread of the coronavirus. Therefore, in this study, a total of 200 people were surveyed on the top three mobile medical applications in China, and the data of 120 people who actually used medical applications were analyzed based on Venkatesh's UTAUT2 theory. A study was conducted on the intent to use and the factors affecting the in-law behavior. First, it has become clear that the interactive characteristics, expectations for effort, price value, interest in privacy, habits, and promotional conditions have a positive impact on the user's use. Second, it was investigated that the user's intention to use influences the behavior of use, and among the intentions of use, it was found that the mobilization characteristic expectation, hedonistic motivation, price value, habits, and promotion conditions affect the use behavior. Third, a study result was derived that the controlling variables such as gender, age, school age, and annual income do not affect the user's intention to use mobile medical applications as a controlling variable. Finally, due to the nature of mobile devices that use the Internet, various security vulnerabilities exist, and this can cause great damage or personal and social impact. Therefore, for the development of mobile medical services in China, it is necessary to re-establish a research model through comprehensive and in-depth considerations to supplement these problems in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.129-137
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• 2020

In performing the structural analysis, the foundation is considered to be a fixed end as a plastic hinge model. In this study, the displacements of the foundation, pier, and shoe were compared when the foundation modeled as a fixed end, a shallow foundation constructed on bedrock of 2m depth, and a pile foundation constructed in the 10m to 20m depth of bedrock. The shear force was also compared, and the probability of damage was calculated and compared for the critical condition. When calculated as a fixed end, the displacement of the foundation converged to 0mm, but the shallow foundation built on the bedrock with a depth of 2m caused relatively displacement, and the pile foundation constructed to contact the bedrock with a depth of 18m caused a larger displacement. In addition, it was analyzed that the displacement of the foundation, which is the lower structure, affects the displacement of the super structure, but the difference in shear force applied to the foundation was insignificant in the three cases. There was no difference between the shallow foundation and the pile foundation in the influence on the displacement of the top of the pier, but there was a big difference from the analysis assuming as a fixed end.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.424-433
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• 2021

Recent climate change has caused abnormal weather phenomena all over the world and a lot of damage in many fields of society. Particularly, a lot of recent damages were due to extreme precipitation, such as torrential downpour or drought. The objective of this study was to analyze the temporal and spatial changes in the precipitation pattern in South Korea. To achieve this objective, this study selected some of the precipitation indices suggested in previous studies to compare the temporal characteristics of precipitation induced by climate change. This study selected ten ASOS observatories of the Korea Meteorological Administration to understand the change over time for each location with considering regional distribution. This study also collected daily cumulative precipitation from 1951 to 2020 for each point. Additionally, this study generated high-resolution national daily precipitation distribution maps using an orographic precipitation model from 1981 to 2020 and analyzed them. Temporal analysis showed that although annual cumulative precipitation revealed an increasing trend from the past to the present. The number of precipitation days showed a decreasing trend at most observation points, but the number of torrential downpour days revealed an increasing trend. Spatially, the number of precipitation days and the number of torrential downpour days decreased in many areas over time, and this pattern was prominent in the central region. The precipitation pattern of South Korea can be summarized as the fewer precipitation days and larger daily precipitation over time.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.194-208
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• 2021

The Hwanggang Dam in North Korea is located upstream of the Imjin River which is a shared river in the border area. It is known to have a reservoir capacity of 350 million cubic meters and releases a discharge primarily for generating hydroelectric power and partly for transferring to the Yesung River basin. Due to the supply of water from the Hwanggang Dam to another basin, the flow of the Imjin River has decreased, which has a negative impact on the water supply, river maintenance flow, water quality, and ecological environment in Korea. However, due to the special national security issue of the South and North Korea border region, the hydrological data is not shared, and the operation method of the Hwanggang Dam is unknown, so there is a risk of damage to the southern part of the downstream area. In this study, the monthly diversion as the long-term runoff concept was derived through the calibrated hydrological model based on optical remotely sensed Images and water balance analysis. As a result of the water balance analysis from January 2019 to September 2021, the average diversion of the Hwanggang Dam was 29.2m³/s, which is equivalent to 922 million tons per year and 45.6% of the annual inflow of 2.02 million tons into the Hwanggang Dam.