• Clinical and Experimental Vaccine Research
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• v.11 no.2
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• pp.184-192
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• 2022

The coronavirus disease 2019 (COVID-19) pandemic revolutionized the vaccine market and initiated the momentum for alternative routes of administration for vaccines. The intranasal route of immunization is one such possibility that appears to be the most promising since it has some significant advantages, particularly in the prevention of respiratory infection. To analyze and summarize the role of nasal vaccines over conventional vaccines during COVID-19 and the need for the nasal vaccine as a booster shot. In this narrative review, the required data was retrieved using keywords "COVID-19," "Intranasal," "Immunity," "Nasal spray," and "Mucosal" in databases including PubMed, Scopus, Embase, Science Direct, and Web of Sciences. The results of the study showed that the nasal vaccines were both effective and protective according to the current researches approaching during the COVID-19 period and the preclinical and clinical phase trials prove the intranasal vaccination elicits more robust and cross-protective immunity than conventional vaccines. In this narrative review article, mechanisms across the nasal mucosa will be briefly presented and the current status of nasal vaccines during the COVID-19 pandemic is summarized, and advantages over traditional vaccines are provided. Furthermore, after exploring the primary benefits and kinetics of nasal vaccine, the potential for consideration of nasal vaccine as a booster dose is also discussed.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.399-406
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• 2024

This research paper explores the integration of Unmanned Aerial Vehicle (UAV)-based remote sensing survey methods, specifically LiDAR and photogrammetry, into the measurement and payment processes of beach fill construction projects managed by the U.S. Army Corps of Engineers (USACE). The primary objective is to evaluate the feasibility, accuracy, and cost-effectiveness of UAV technology in contrast to traditional topographic and hydrographic survey methods. The methodology includes a comprehensive literature review, case studies, accuracy standard assessments, and a detailed cost comparison between conventional and UAV-based survey techniques. The findings reveal that UAV-based remote sensing can offer significant improvements in terms of efficiency and cost savings. UAVs are capable of capturing large data volumes quickly with reduced manpower and equipment needs. However, the accuracy of UAV surveys is contingent upon environmental conditions and the proper staging of control points. Moreover, the initial investment and operational costs of UAV equipment are substantial and warrant further analysis. The paper argues for flexibility in measurement and payment methodologies during the project design phase to accommodate UAV technology. While environmental conditions may occasionally necessitate traditional survey methods, the study suggests that regions like the Florida Peninsula, with clearer water and more favorable weather, are particularly well-suited for the implementation of UAV-based surveys. The significance of this study lies in its potential to guide future beach fill construction projects, promoting more efficient and cost-effective survey methods while adhering to accuracy standards and environmental considerations.

• Journal of Sensor Science and Technology
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• v.33 no.5
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• pp.265-273
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• 2024

With the advent of artificial intelligence and Internet of Things, demands for high-performance sensors with high sensitivity and ultrafast response for big data acquisition and processing have increased. VO₂, a strongly correlated material, has been shown to exhibit a reversible and abrupt resistance change in the sub-nanosecond scale through a phase transition from an insulating to a metallic state at 68℃. The metal-insulator transition (MIT) of VO₂ provides the potential for the development of highly sensitive and ultrafast high-performance sensors. This is because it can be triggered by various external stimuli, such as heat, light, gas adsorption/desorption, and strain. Therefore, attempts have been made to develop high-performance sensors by controlling the MIT of VO₂ in response to external stimuli. This study reviewed recent progress in various VO₂-based sensors that utilize MIT, including photodetectors, gas sensors, and strain sensors. This review is expected to serve as an overview of the approaches for controlling the MIT behavior of VO₂ and provide insights into the design of high-performance sensors that exploit MIT.

• Economic and Environmental Geology
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• v.45 no.4
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• pp.351-363
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• 2012

In order to develop the evaluation techniques for the potential sulfide ore reserves, the relationships between the modal vol.%, grain sizes and textural characteristics of the constituent minerals (e.g., sulfides, oxides and skarn minerals) and the Spectral Induced Polarization (SIP) phase differences are examined for the nine rock cores collected from the Gagok Pb-Zn skarn deposit. The Gagok Pb-Zn skarn deposit occurs mainly along the intrusive contact between the Cretaceous granitic rocks and Cambrian Myobong slate and Pungchon limestone. The nine rock cores have been grouped into three showing distinctive SIP phase differences: the highest (Group I), intermediate (Group II) and lowest (Group III). In relation with the modal vol.% of minerals, Group I is characterized by higher pyrrhotite (25-38 vol.%) and amphibole (40-55 vol.%); Group II by intermediate pyrrhotite (7-13 vol.%) and higher garnet (44-68 vol.%); and lower pyrrhotite (1-7 vol.%) and higher pyroxene (24-66 vol.%) stand for Group III. Furthermore, the grains of all the major constituent minerals become smaller from Group I (<5 mm) through Group II (<2.5 mm) to Group III (<1.6 mm). In particular, the pyrrhotite contents and their grain sizes show logarithmic correlation with the SIP phase differences, Although we present here the results solely from nine samples, the systematic interrelations especially for pyrrhotite indicate the potential ability of SIP measurements as a new mine-evaluation technique for the sulfide ore reservoir.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.147-158
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• 2004

Laboratory dynamic tests are carried out to assess the liquefaction potential of saturated sands in most countries. However, simple results such as the maximum cyclic shear stress and the number of cycles at initial liquefaction are used in the experimental assessment of liquefaction potential, even though various results can be obtained from the dynamic test. In addition, it seemed to be inefficient because more than three dynamic tests with different stress ratio have to be carried out to draw a liquefaction resistance experimental curve. To improve the present assessment method fur liquefaction potential, a new critical resistible characteristic far soil liquefaction is proposed and verified through conventional cyclic triaxial tests with Jumunjin sand. In the proposed method, various experimental data such as effective stress path, stress-strain relationship, and the change of excess pore water pressure can be used in the determination of cumulative plastic shear strains at every 1/4 cycle. Especially, the critical cumulative plastic shear strain to initiate liquefaction can be defined in a specific point called a phase change point in the effective stress path and it can be calculated from a hysteric curve of stress-strain relationship up to this point. Through this research, it is found that the proposed cumulative plastic shear strain can express the dissipated energy to resist dynamic loads and consider the realistic soil dynamic behavior of saturated sands reasonably. It is also found that the critical plastic shear strain can be used as a registible index of soils to represent the critical soil dynamic state, because it seems to include no effect of large deformation.

• Journal of Intelligence and Information Systems
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• v.28 no.1
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• pp.69-88
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• 2022

One of the characteristics of South Korea's economic structure is that it is highly dependent on exports. Thus, many businesses are closely related to the global economy and diplomatic situation. In addition, small and medium-sized enterprises(SMEs) specialized in exporting are struggling due to the spread of COVID-19. Therefore, this study aimed to develop a model to forecast exports for next year to support SMEs' export strategy and decision making. Also, this study proposed a strategy to recommend promising export countries of each item based on the forecasting model. We analyzed important variables used in previous studies such as country-specific, item-specific, and macro-economic variables and collected those variables to train our prediction model. Next, through the exploratory data analysis(EDA) it was found that exports, which is a target variable, have a highly skewed distribution. To deal with this issue and improve predictive performance, we suggest a separated learning method. In a separated learning method, the whole dataset is divided into homogeneous subgroups and a prediction algorithm is applied to each group. Thus, characteristics of each group can be more precisely trained using different input variables and algorithms. In this study, we divided the dataset into five subgroups based on the exports to decrease skewness of the target variable. After the separation, we found that each group has different characteristics in countries and goods. For example, In Group 1, most of the exporting countries are developing countries and the majority of exporting goods are low value products such as glass and prints. On the other hand, major exporting countries of South Korea such as China, USA, and Vietnam are included in Group 4 and Group 5 and most exporting goods in these groups are high value products. Then we used LightGBM(LGBM) and Exponential Moving Average(EMA) for prediction. Considering the characteristics of each group, models were built using LGBM for Group 1 to 4 and EMA for Group 5. To evaluate the performance of the model, we compare different model structures and algorithms. As a result, it was found that the separated learning model had best performance compared to other models. After the model was built, we also provided variable importance of each group using SHAP-value to add explainability of our model. Based on the prediction model, we proposed a second-stage recommendation strategy for potential export countries. In the first phase, BCG matrix was used to find Star and Question Mark markets that are expected to grow rapidly. In the second phase, we calculated scores for each country and recommendations were made according to ranking. Using this recommendation framework, potential export countries were selected and information about those countries for each item was presented. There are several implications of this study. First of all, most of the preceding studies have conducted research on the specific situation or country. However, this study use various variables and develops a machine learning model for a wide range of countries and items. Second, as to our knowledge, it is the first attempt to adopt a separated learning method for exports prediction. By separating the dataset into 5 homogeneous subgroups, we could enhance the predictive performance of the model. Also, more detailed explanation of models by group is provided using SHAP values. Lastly, this study has several practical implications. There are some platforms which serve trade information including KOTRA, but most of them are based on past data. Therefore, it is not easy for companies to predict future trends. By utilizing the model and recommendation strategy in this research, trade related services in each platform can be improved so that companies including SMEs can fully utilize the service when making strategies and decisions for exports.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1998.10a
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• pp.2-4
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• 1998

Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.311-323
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• 2023

This study aimed to investigate the impact of Bacillus subtilis-based probiotics and oregano essential oil on the production performance, egg quality, and intestinal morphology of late-phase laying hens (69-weeks). A total of 150 laying hens of 69-week-old were randomly allotted into 6 treatment groups with 5 replicates of 5 birds in each replicate. Laying hens were divided into high (H) and average (A) egg production groups prior to the trial. The hens in each group were supplemented with Bacillus subtilis, or oregano essential oil: CON, a basal diet; BS, basal diet plus 3 × 10⁸ CFU/kg feed Bacillus subtilis; OEO, basal diet plus 0.3 g/kg feed oregano essential oil. Egg performance, blood characteristics, egg quality, and intestinal morphology of the late-phase laying hens were evaluated. Both BS and OEO significantly enhanced (P<0.05) egg production compared to CON in high egg production. The blood characteristics indicated no significant differences based on the egg production and the supplementation of BS and OEO in the late-phase laying hens. The eggshell strength was significantly improved (P<0.05) in both OEO compared to both CON. A significantly decreased (P<0.05) the villus height to crypt depth ratio (VH/CD) in the ileum compared to H, and in the treatment groups supplemented with BS and OEO, VH/CD showed a significant increase (P<0.05) compared to both CON. These results suggest that the supplementation of Bacillus subtilis and oregano essential oil in the diet of late-phase laying hens could serve as a potential strategy to enhance egg production, egg quality, and gut health.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.1
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• pp.13-21
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• 2022

Mushroom waste medium refers to the waste biomass generated after mushroom cultivating. And, the burden of treatment on mushroom farmhouse is increasing due to the absence of appropriate treatment method and increase of treatment costs of the mushroom waste medium. In this study, in order to assess the energy value of mushroom waste medium by an anaerobic digestion, methane potential and anaerobic organic matter decomposition characteristics were investigated. The theoretical methane potential(B_th) of mushroom medium(MM) was 0.481 Nm³-CH₄/kg-VS_added, and the B_th of mushroom waste medium(MWM) was 0.451 Nm³-CH₄/kg-VS_added. The biochemical methane potential(B_u-exp) of MWM was increased by 18% from 0.155 for MM to 0.183 Nm³-CH₄/kg-VS_added for MWM. In the reaction kinetics analysis by the Modified Gompertz model, the maximum methane production rate(R_m) was increased from 4.59 for MM to 7.21 mL/day for MWM and the lag growth phase time(λ) was decreased from 2.78 for MM to 1.96 days for MWM. In the reaction kinetics analysis by the parallel first order kinetics model, the easily degradable organic matter(VS_e) content was increased by 5.89% and the persistently degradable organic matter(VS_p) content was 2.03% in MWM, and the non-degradable organic matter(VS_NB) content was decreased by 7.85%. Therefore, it was evaluated that the anaerobic digestion efficiency of MWM was increased. The anaerobic digestion efficiency of MWM was assessed to be more improved than that of MM.

• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.279-285
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• 2008

Korea Institute of Geoscience & Mineral Resources (KIGAM) carried out 2 dimensional multi-channel seismic surveys for Domi-Basin of east-southern part of Jeju Island, South Sea, Korea in 2007. The purpose of this survey is to investigate the structure of acoustic basement and the potential of energy resources in the Korean shelf. It is essential to produce fine stack and migration section to understand the structure of basement. However a basement can not be clearly defined where multiples exist between sea surface and seafloor. This study aimed at designing the optimal data processing parameter, especially to eliminate the peg-leg multiples. Main data processing procedure is composed of minimum phase predictive deconvolution, velocity analysis and Radon filter. We tested the efficiency of processing parameter from stack sections of each step. Our results confirmed that processing parameters are suitable for the seismic data of Domi-Basin.