• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.409-418
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• 2019

Debris flows occur in mountainous areas due to heavy rains resulting from climate change and result in disasters in the downstream area. The purpose of this study is to estimate the impact force of a debris flow when a check dam according is installed in various locations in the channel of a highly mountainous area. A Finite Differential Element Method (FDM) model was used to simulate the erosion and deposition based on the equation for the mass conservation and momentum conservation while considering the continuity of the fluid. The peak impact force from the debris flow occurred at 0 to 5 sec and 15 to 20 sec. When the supplied water discharge was increased, greater peak impact force was generated at 16 to 19 sec. This means that when increasing the water supply, the velocity of the debris flow became faster, which results in increased energy of the consolidation between the particles of the water and the sediment made. If a number of check dams were to be set up, it would be necessary to investigate the impact force at each location of the check dam. The results of this study could provide useful information in predicting the impact force of the debris flow and in installing the check dams in appropriate locations.

• Journal of Life Science
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• v.28 no.12
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• pp.1469-1476
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• 2018

Occurrence of the Warburg effect in solid tumors causes resistance to cancer chemotherapy, and targeting energy metabolisms such as aerobic glycolysis is a potential strategy for alternative treatment. Dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), shifts glucose metabolism from aerobic glycolysis to oxidative phosphorylation (OxPhos) in many cancers. In this study, we investigated the anticancer effect of DCA on a human anaplastic thyroid cancer (ATC) cell line, 8505C. We found that DCA selectively inhibits cell proliferation of the 8505C line but not of a normal thyroid line. In 8505C, the cell cycle was arrested at the G1/S phase with DCA treatment as a result of decreased antiapoptotic proteins such as $HIF1{\alpha}$, PDK1, and Bcl-2 and increased proapoptotic proteins such as Bax and p21. DCA treatment enhanced the production of reactive oxygen species which consequently induced cell cycle arrest and apoptosis. Interestingly, DCA treatment not only reduced lactate production but also increased the expression of sodium-iodine symporter, indicating that it restores the OxPhos of glucose metabolism and the iodine metabolism of the ATC. Taken together, our findings suggest that PDK inhibitors such as DCA could be useful anticancer drugs for the treatment of ATC and may also be helpful in combination with chemotherapy and radiotherapy.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.2
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• pp.97-109
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• 2019

Degree days have been determined using temperature data measured at nearby weather stations to a site of interest to produce information for supporting decision-making on agricultural production. Alternatively, the data products of Moderate Resolution Imaging Spectroradiometer (MODIS) can be used for estimation of degree days in a given region, e.g., Korean Peninsula. The objective of this study was to develop a simple tool for processing the MODIS product for estimating cooling degree days (CDD), which would help assessment of heat stress conditions for a crop as well as energy requirement for greenhouses. A set of scripts written in R was implemented to obtain temperature profile data for the region of interest. These scripts had functionalities for processing spatial data, which include reprojection, mosaicking, and cropping. A module to extract air temperature at the surface pressure level was also developed using R extension packages such as rgdal and RcppArmadillo. Random forest (RF) models, which estimate mean temperature and CDD with a different set of MODIS data, were trained at 34 sites in South Korea during 2009 - 2018. Then, the values of CDD were calculated over Korean peninsula during the same period using those RF models. It was found that the CDD estimates using the MODIS data explained >74% of the variation in the CDD measurements at the weather stations in North Korea as well as South Korea. These results indicate that temperature data derived from the MODIS atmospheric products would be useful for reliable estimation of CDD. Our results also suggest that the MODIS data can be used for preparation of weather input data for other temperature-based agro-ecological models such as growing degree days or chill units.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.202-209
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• 2019

The primary productivity and production rate of photosynthetic pigment of periphyton and phytoplankton were estimated using a $^{13}C$ stable labeling technique in May 2011, in the waterfront of Lake Paldang. Primary productivity of periphyton ($28.15mgC\;m^{-2}\;d^{-1}$) was higher than phytoplankton production ($0.14mgC\;m^{-2}\;d^{-1}$). The net production rates of photosynthetic pigments(Chl a and Fucoxanthin) of periphyton were $2.53ngC\;m^{-2}\;d^{-1}$ and $0.12ngC\;m^{-2}\;d^{-1}$, respectively. On the other hand, the net production rate of pigments on phytoplankton (Chl a : $0.023ngC\;m^{-2}\;d^{-1}$, Fucoxanthin: $0.002ngC\;m^{-2}\;d^{-1}$) was lower than that of periphyton. Specific production rates of individual pigments of phytoplankton to the total primary productivity indicate the predominance of diatom (Fucoxanthin) species in phytoplankton assemblage in Lake Paldang. The net individual production rate of pigments by $^{13}C$ tracer was a useful tool to estimate the contribution of each phytoplankton class for total primary productivity, and it is possible to calculate the seasonal contribution of each phytoplankton class to the total primary productivity in the aquatic ecosystems. This study is the first report on photosynthetic pigment production rates of periphyton and phytoplankton.

• Journal of the Korean GEO-environmental Society
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• v.22 no.2
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• pp.35-39
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• 2021

Photogrammetry using drone can produce high-resolution ortho image and acquire high-accuracy 3D information, which is useful. Therefore, this study attempted to determine the possibility of using drone-photogrammetry in park construction by producing a topographic map using drone-photogrammetry and analyzing the problems and accuracy generated during production. For this purpose, we created ortho image and DSM (digital surface model) using drone images and created topographic status map by vectorizing them. Accuracy was compared based on topographic status map by GPS (global positioning system) and TS (total station). The resulting of analyzing mean of the residuals at check points showed that 0.044 m in plane and 0.066 m in elevation, satisfying the tolerance range of 1/1,000 numerical maps, and result of compared lake size showed a difference of about 4.4%. On the other hand, it was difficult to obtain accurate height values for terrain in which existed vegetation when producing the topographic map, and in the case of underground buried objects, it is not possible to confirm it in the image, so direct spatial information acquisition was necessary. Therefore, it is judged that the topographic status map using drone photogrammetry can be efficiently constructed if direct spatial data acquisition is achieved for some terrain.

• Journal of Convergence for Information Technology
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• v.11 no.1
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• pp.136-142
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• 2021

Open-pit mine development requires continuous management because of topographical changes and there is a risk of accidents if the current status survey is performed directly in the process of calculating the earthwork. In this study, the application of UAV photogrammetry, which can acquire spatial information without direct human access, was applied to open-pit mines development area and analyzed the accuracy, earthwork, and mountain restoration plan to determine its applicability. As a result of accuracy analysis at checkpoint using ortho image and Digital Surface Model(DSM) by UAV photogrammetry, Root Mean Square Error(RMSE) is 0.120 m in horizontal and 0.150 m in vertical coordinates. This satisfied the tolerance range of 1:1,000 digital map. As a result of the comparison of the earthwork, UAV photogrammetry yielded 11.7% more earthwork than the conventional survey method. It is because UAV photogrammetry shows more detailed topography. And result of monitoring mountain restoration showed possible to determine existence of rockfall prevention nets and vegetation. If the terrain changes are monitored by acquiring images periodically, the utility of UAV photogrammetry will be further useful to open-pit mine development.

• Journal of the Korea Society for Simulation
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• v.30 no.2
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• pp.11-22
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• 2021

Sonobuoy is widely used as a very important sensor in combat management system using P-3 patrol aircraft due to its advantages of rapid searching into wide exploration range. It is necessary to verify the performance of developed sonobuoy system using various maritime test data in order to be successfully applied in combat management system. But it is difficult to acquire various real maritime data because it needs much time and effort. Therefore we have developed in this paper a synthetic signal generator and a simulator that they can verify the performance of sonobuoy system and evaluate its operational effectiveness without conducting maritime test. We have synthesized target signals based on the characteristics of underwater sound sources, and then developed the synthesized signal generator which consider to sound propagation etc. like as underwater environment. And in the simulator development we use a HMI technique to enhance the convenience of operator, and design to verify the performance of sonobuoy system. The developed signal generator and simulator can be used as useful tools to evaluate the operational effectiveness such as optimal deployment of sonobuoy in combat management system using P-3 patrol aircraft.

• Journal of Korean Society of Disaster and Security
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• v.14 no.1
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• pp.9-21
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• 2021

Recently, the importance of eco-friendly power generation facility using renewable energy has newly appeared. Hydropower plant is a very important source of electricity generation and supply which is very important to secure safety because it is commonly connected with multi facility and operated on a large scale. In this study, a scenario-based analysis method was suggested to assess vulnerability of a penstock system caused by water hammer commonly occurred in the operation of hydropower plants. A hypothetical hydropower plant was used to demonstrate the applicability of a transient analysis model. In order to verify reliability of the model, the prediction of pressure behaviors were compared with the results of commercial model (SIMSEN) and measured data, then a real hydroelectric power plant was applied to develop all potential water hammer scenarios during the actual operation. The scenario-based simulation and vulnerability assessment for water hammer in the penstock system were performed with internal and external load conditions. The simulation results indicated that the vulnerability of a penstock system was varied with the operating conditions of hydropower facilities and significantly affected by load combination consisting of different load scenarios. The proposed numerical method could be an useful tool for the vulnerabilityty assessment of the hydropower plants due to water hammer.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.149-169
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• 2022

Indonesia coal is widely consumed as a major energy source in Asian countries, such as China, India, and Korea. In the paper, the characteristics of the coal-bearing basin and coal deposits in Indonesia are comprehensively reviewed using the exploration data accumulated through the coal exploration projects supported by Korean government subsidy. Cenozoic coal bearing sedimentary basins in Indonesia extensively contain coal deposits and are most productive in East Asia. Properties of coal deposits are variable depending on stratigraphy, depositional histories and tectonics. Eocene coal deposits tend to have thinner coal thickness and fewer numbers of coal seams, but have been major exploration targets due to higher calorific value and good coal quality. Late Oligocene-Early Miocene coal deposits occur in small scales, but are suitable enough for small to medium-sized coal mines. Miocene-Pliocene coal deposits, which are widely distributed across East Kalimantan and Sumatra, are being actively mined by taking advantage of thick coal thickness and abundant reserves in spite of their lower calorific values. The experience of various exploration informs that we need to have an overall understanding on geological conditions for successful coal exploration. The details on coal-bearing basin and coal deposits in Indonesia provided through the paper will be useful data for up-coming exploration activities by Korean companies.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.193-201
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• 2022

5-HMF(5-Hydroxymethylfurfural) and LA(levulinic acid) derived from biomass are green platform chemicals, which have a wide of potential applications as biofules and biochemicals. In this study, the kinetics of LA formation from glucose decomposition with various concentration of sulfuric acid at different temperature was investigated. The experiments were performed in a broad temperature (140-200 ℃), using H₂SO₄ (1-3 wt%) as the catalyst. Glucose solution was made by dissolving 1 g of glucose in 10 ml of H₂SO₄ solution. The reactions rates increased with temperature and the activation energy showed a similar tendency to previous reported values. Reaction time for maximum concentration of 5-HMF decreased as the temperature increased. Furthermore, the decomposition of 5-HMF was fast as the acid concentration increased. Reaction time to reach maximum concentration of levulinic acid was reduced as the acid concentration increased. Continuing to raise the temperature decreased the maximum concentration of levulinic acid and increased the amount of humins. On the basis of results, kinetic parameters help to understand mechanism of LA and 5-HMF. In addition, this study provides useful information to achieve high concentration of LA and 5-HMF from biomass.