• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.2
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• pp.123-131
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• 2021

The buffer is a key component of an engineered barrier system that safeguards the disposal of high-level radioactive waste. Buffers are located between disposal canisters and host rock, and they can restrain the release of radionuclides and protect canisters from the inflow of ground water. Since considerable heat is released from a disposal canister to the surrounding buffer, the thermal conductivity of the buffer is a very important parameter in the entire disposal safety. For this reason, a lot of research has been conducted on thermal conductivity prediction models that consider various factors. In this study, the thermal conductivity of a buffer is estimated using the machine learning methods of: linear regression, decision tree, support vector machine (SVM), ensemble, Gaussian process regression (GPR), neural network, deep belief network, and genetic programming. In the results, the machine learning methods such as ensemble, genetic programming, SVM with cubic parameter, and GPR showed better performance compared with the regression model, with the ensemble with XGBoost and Gaussian process regression models showing best performance.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.155-162
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• 2022

This study investigated the immunostimulatory effect of enzymatic porcine placental hydrolyzate (EPPH) in cyclophosphamide (Cy)-treated rats. This effect of EPPH prevented Cy-induced decreases in body, spleen, and thymus weights and natural killer (NK) cell activity. The numbers of immune cells, such as white blood cells, granulocytes, and lymphocytes, and mid-range absolute counts were significantly higher compared to the control group. The levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-2, IL-12, and immunoglobulin G (IgG) were notably reduced by Cy, while EPPH prevented these effects. Histopathological analysis of spleen samples revealed the protective effect of EPPH against Cy-induced immunosuppression. The findings demonstrate that EPPH can alleviate immunosuppression by cell viability, tissue damage, and regulation of the levels of cytokines. EPPH may have value as a component of immunostimulatory agents or an ingredient in functional foods.

• Geophysics and Geophysical Exploration
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• v.25 no.4
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• pp.177-188
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• 2022

Recently, the application of distributed acoustic sensors (DAS), which can replace geophones and seismometers, has significantly increased along with interest in micro-seismic monitoring technique, which is one of the CO₂ storage monitoring techniques. A significant amount of temporally and spatially continuous data is recorded in a DAS monitoring system, thereby necessitating fast and accurate data processing techniques. Because event detection and seismic phase picking are the most basic data processing techniques, they should be performed on all data. In this study, a machine learning-based P, S wave phase picking algorithm was developed to compensate for the limitations of conventional phase picking algorithms, and it was modified using a transfer learning technique for the application of DAS data consisting of a single component with a low signal-to-noise ratio. Our model was constructed by modifying the convolution-based EQTransformer, which performs well in phase picking, to the ResUNet structure. Not only the global earthquake dataset, STEAD but also the augmented dataset was used as training datasets to enhance the prediction performance on the unseen characteristics of the target dataset. The performance of the developed algorithm was verified using K-net and KiK-net data with characteristics different from the training data. Additionally, after modifying the trained model to suit DAS data using the transfer learning technique, the performance was verified by applying it to the DAS field data measured in the Pohang Janggi basin.

• Journal of Environmental Science International
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• v.32 no.12
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• pp.899-914
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• 2023

Various seeding materials for cloud seeding are being used, and sodium chloride powder is one of them, which is commonly used. This study analyzed the experimental results of multi-aircraft cloud seeding in connection with Republic of Korea Air Force (CN235) and KMA/NIMS(Korea Meteorological Administration/National Institute of Meteorological Sciences) Atmospheric Research Aircraft. Powdered sodium chloride was used in CN235 for the first time in South Korea. The analysis of the cloud particle size distributions and radar reflectivity before and after cloud seeding showed that the growth efficiency of powdery seeding material in the cloud is slightly higher than that of hygroscopic flare composition in the distribution of number concentrations by cloud aerosol particle diameter (10 ~ 1000 ㎛). Considering the radar reflectivity, precipitation, and numerical model simulation, the enhanced precipitation due to cloud seeding was calculated to be a maximum of 3.7 mm for 6 hours. The simulated seeding effect area was about 3,695 km², which corresponds to 13,634,550 tons of water. In the precipitation component analysis, as a direct verification method, the ion equivalent concentrations (Na⁺, Cl^-, Ca²⁺) of the seeding material at the Bukgangneung site were found to be about 1000 times higher than those of other non-affected areas between about 1 and 2 hours after seeding. This study suggests the possibility of continuous multi-aircraft cloud seeding experiments to accumulate and increase the amount of precipitation enhancement.

• Geomechanics and Engineering
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• v.35 no.2
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• pp.195-208
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• 2023

The nodular diaphragm wall (NDW) is a novel type of foundation with favorable engineering characteristics, which has already been utilized in high-rise buildings and high-speed railways. Compared to traditional diaphragm walls, the NDW offers significantly improved vertical bearing capacity due to the presence of nodular parts while reducing construction time and excavation work. Despite its potential, research on the vertical bearing characteristics of NDW requires further study, and the investigation and visualization of its displacement pattern and failure mode are scant. Meanwhile, the measurement of the force component acting on the nodular parts remains challenging. In this paper, the vertical bearing characteristics of NDW are studied in detail through the indoor model test, and the displacement and failure mode of the foundation is analyzed using particle image velocimetry (PIV) technology. The principles and methods for monitoring the force acting on the nodular parts are described in detail. The research results show that the nodular part plays an essential role in the bearing capacity of the NDW, and its maximum load-bearing ratio can reach 30.92%. The existence of the bottom nodular part contributes more to the bearing capacity of the foundation compared to the middle nodular part, and the use of both middle and bottom nodular parts increases the bearing capacity of the foundation by about 9~12% compared to a single nodular part of the NDW. The increase in the number of nodular parts cannot produce a simple superposition effect on the resistance born by the nodular parts since the nodular parts have an insignificant influence on the exertion and distribution of the skin friction of NDW. The existence of the nodular part changes the displacement field of the soil around NDW and increases the displacement influence range of the foundation to a certain extent. For NDWs with three different nodal arrangements, the failure modes of the foundations appear to be local shear failures. Overall, this study provides valuable insights into the performance and behavior of NDWs, which will aid in their effective utilization and further research in the field.

• Journal of Korea Water Resources Association
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• v.56 no.spc1
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• pp.1007-1014
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• 2023

Two-dimensional flow analysis, a fundamental component of hydrodynamics, plays a pivotal role in numerically simulating fluid behavior in rivers and waterways. This modeling approach heavily relies on parameters such as eddy viscosity and roughness coefficient to accurately represent flow characteristics. Therefore, combination of appropriate parameters is very important to accurately simulate flow characteristics. In this study, an automation algorithm was developed and applied to find the optimal combination of parameters. Previously, when applying a two-dimensional flow analysis model, former researchers usually depend on the empirical approach, which causes many difficulties in finding optimal variable values. Using the experimental data, we tracked errors according to the combination of various parameters and applied the algorithm that can determine the optimal combination of parameters with the Python language. The automation algorithm can easily determine the most accurate combination by comparing the flow velocity error values among the two-dimensional flow analysis results among the combinations of 121 (11×11) parameters. In the perspective of utilizing automation algorithm, there is an expected high utility in promptly and straightforwardly determining the optimal combination of parameters with the smallest error.

• Journal of Ginseng Research
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• v.48 no.1
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• pp.31-39
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• 2024

Background: Ginsenoside Rg3, a primary bioactive component of red ginseng, has anti-cancer effects. However, the effects of Rg3-enriched ginseng extract (Rg3RGE) on apoptosis and autophagy in breast cancer have not yet been investigated. In the present study, we explored the anti-tumor effects of Rg3RGE on breast cancer cells stimulated CoCl₂, a mimetic of the chronic hypoxic response, and determined the operative mechanisms of action. Methods: The inhibitory mechanisms of Rg3RGE on breast cancer cells, such as apoptosis, autophagy and ROS levels, were detected both in vitro. To determine the anti-cancer effects of Rg3RGE in vivo, the cancer xenograft model was used. Results: Rg3RGE suppressed CoCl₂-induced spheroid formation and cell viability in 3D culture of breast cancer cells. Rg3RGE promoted apoptosis by increasing cleaved caspase 3 and cleaved PARP and decreasing Bcl2 under the hypoxia mimetic conditions. Further, we identified that Rg3RGE promoted apoptosis by inhibiting lysosomal degradation of autophagosome contents in CoCl₂-induced autophagy. We further identified that Rg3RGE-induced apoptotic cell death and autophagy inhibition was mediated by increased intracellular ROS levels. Similarly, in the in vivo xenograft model, Rg3RGE induced apoptosis and inhibited cell proliferation and autophagy. Conclusion: Rg3RGE-stimulated ROS production promotes apoptosis and inhibits protective autophagy under hypoxic conditions. Autophagosome accumulation is critical to the apoptotic effects of Rg3RGE. The in vivo findings also demonstrate that Rg3RGE inhibits breast cancer cell growth, suggesting that Rg3RGE has potential as potential as a putative breast cancer therapeutic.

• Biomolecules & Therapeutics
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• v.32 no.3
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• pp.368-378
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• 2024

Cordycepin, a valuable bioactive component isolated from Cordyceps militaris, has been reported to possess anti-cancer potential and the property to enhance the effects of chemotherapeutic agents in various types of cancers. However, the ability of cordycepin to chemosensitize cholangiocarcinoma (CCA) cells to gemcitabine has not yet been evaluated. The current study was performed to evaluate the above, and the mechanisms associated with it. The study analyzed the effects of cordycepin in combination with gemcitabine on the cancer stem-like properties of the CCA SNU478 cell line, including its anti-apoptotic, migratory, and antioxidant effects. In addition, the combination of cordycepin and gemcitabine was evaluated in the CCA xenograft model. The cordycepin treatment significantly decreased SNU478 cell viability and, in combination with gemcitabine, additively reduced cell viability. The cordycepin and gemcitabine co-treatment significantly increased the Annexin V+ population and downregulated B-cell lymphoma 2 (Bcl-2) expression, suggesting that the decreased cell viability in the cordycepin+gemcitabine group may result from an increase in apoptotic death. In addition, the cordycepin and gemcitabine co-treatment significantly reduced the migratory ability of SNU478 cells in the wound healing and trans-well migration assays. It was observed that the cordycepin and gemcitabine cotreatment reduced the CD44^highCD133^high population in SNU478 cells and the expression level of sex determining region Y-box 2 (Sox-2), indicating the downregulation of the cancer stem-like population. Cordycepin also enhanced oxidative damage mediated by gemcitabine in MitoSOX staining associated with the upregulated Kelch like ECH Associated Protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) expression ratio. In the SNU478 xenograft model, co-administration of cordycepin and gemcitabine additively delayed tumor growth. These results indicate that cordycepin potentiates the chemotherapeutic property of gemcitabine against CCA, which results from the downregulation of its cancer-stem-like properties. Hence, the combination therapy of cordycepin and gemcitabine may be a promising therapeutic strategy in the treatment of CCA.

• Journal of Digital Convergence
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• v.21 no.3
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• pp.1-14
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• 2023

This raises the question of how competitive advantage can be created, prompting firms to enhance their capacity for change. In this context, the role of knowledge creation becomes increasingly vital. This research aims to explore the role of intellectual capital and how to improve knowledge cration ability through absorptive capacity framework. It examines the links among knowledge acquisition, learning of new knowledge, knowledge creation, intellectual capital, and competitive advantage, drawing from both internal and external sources. The study focuses on small and medium-sized supplier firms in Korea, with data collected from 15 industries, totaling 106 responses. The research model employs structural equation modeling (SEM) and utilizes AMOS 22 for analysis. As anticipated, all hypotheses were supported. The study provides robust evidence that absorptive capacity is a pivotal factor in cultivating suppliers' competitive advantage. Furthermore, it posits that intellectual capital should be viewed as a criucial component of suppliers' knowledge stock, significantly enhancing the impact of absorptive capacity on their competitive edge. Future studies should aim to validate the research model in different international settings or across multinational corporations to enhance its generalizabulity.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.345-357
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• 2023

Nuclear forensics has been understood as a mendatory component in the international society for nuclear material control and non-proliferation verification. Radiochronometry of nuclear activities for nuclear forensics are decay series characteristics of nuclear materials and the Bateman equation to estimate when nuclear materials were purified and produced. Radiochronometry values have uncertainty of measurement due to the uncertainty factors in the estimation process. These uncertainties should be calculated using appropriate evaluation methods that are representative of the accuracy and reliability. The IAEA, US, and EU have been researched on radiochronometry and uncertainty of measurement, although the uncertainty calculation method using the Bateman equation is limited by the underestimation of the decay constant and the impossibility of estimating the age of more than one generation, so it is necessary to conduct uncertainty calculation research using computer simulation such as Monte Carlo method. This highlights the need for research using computational simulations, such as the Monte Carlo method, to overcome these limitations. In this study, we have analyzed mathematical models and the LHS (Latin Hypercube Sampling) methods to enhance the reliability of radiochronometry which is to develop an uncertainty algorithm for nuclear material radiochronometry using Bateman Equation. We analyzed the LHS method, which can obtain effective statistical results with a small number of samples, and applied it to algorithms that are Monte Carlo methods for uncertainty calculation by computer simulation. This was implemented through the MATLAB computational software. The uncertainty calculation model using mathematical models demonstrated characteristics based on the relationship between sensitivity coefficients and radiative equilibrium. Computational simulation random sampling showed characteristics dependent on random sampling methods, sampling iteration counts, and the probability distribution of uncertainty factors. For validation, we compared models from various international organizations, mathematical models, and the Monte Carlo method. The developed algorithm was found to perform calculations at an equivalent level of accuracy compared to overseas institutions and mathematical model-based methods. To enhance usability, future research and comparisons·validations need to incorporate more complex decay chains and non-homogeneous conditions. The results of this study can serve as foundational technology in the nuclear forensics field, providing tools for the identification of signature nuclides and aiding in the research, development, comparison, and validation of related technologies.