• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.697-703
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• 2022

Due to the recent economic downturn caused by Covid-19 and the unstable international situation, many investors are choosing the derivatives market as a means of investment. However, the derivatives market has a greater risk than the stock market, and research on the market of market participants is insufficient. Recently, with the development of artificial intelligence, machine learning has been widely used in the derivatives market. In this paper, reinforcement learning, one of the machine learning techniques, is applied to analyze the scalping technique that trades futures in minutes. The data set consists of 21 attributes using the closing price, moving average line, and Bollinger band indicators of 1 minute and 3 minute data for 6 months by selecting 4 products among futures products traded at trading firm. In the experiment, DNN artificial neural network model and three reinforcement learning algorithms, namely, DQN (Deep Q-Network), A2C (Advantage Actor Critic), and A3C (Asynchronous A2C) were used, and they were trained and verified through learning data set and test data set. For scalping, the agent chooses one of the actions of buying and selling, and the ratio of the portfolio value according to the action result is rewarded. Experiment results show that the energy sector products such as Heating Oil and Crude Oil yield relatively high cumulative returns compared to the index sector products such as Mini Russell 2000 and Hang Seng Index.

• Membrane Journal
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• v.32 no.4
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• pp.218-226
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• 2022

Hydrogen, a carrier of large-capacity chemical and clean energy, is an important industrial gas widely used in the petrochemical industry and fuel cells. In particular, hydrogen is mainly produced from fossil fuels through steam reforming and gasification, and carbon dioxide is generated as a by-product. Therefore, in order to obtain high-purity hydrogen, carbon dioxide should be removed. This review focused on free-standing polymeric membranes and mixed-matrix membranes (MMMs) that separate hydrogen from carbon dioxide reported in units of Barrer [1 Barrer = 10^-10 cm³ (STP) × cm / (cm² × s × cmHg)]. By analyzing various recently reported papers, the structure, morphology, interaction, and preparation method of the membranes are discussed, and the structure-property relationship is understood to help find better membrane materials in the future. Robeson's upper bound limits for hydrogen/carbon dioxide separation were presented through reviewing the performance and characteristics of various separation membranes, and various MMMs that improve separation properties using technologies such as crosslinking, blending and heat treatment were discussed.

• Journal of the Korean Society of Earth Science Education
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• v.15 no.2
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• pp.224-234
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• 2022

The purpose of this study was to analyze STEAM elements and convergence types that appeared in the creative and convergent activities in elementary school science textbooks, which were converted from the national issuance system to the authorized system in 2022. For this study, 6 elementary school science textbooks for 3rd and 4th graders were selected. And STEAM elements in creative and convergent activities were analyzed by publishers, grade-semesters, and science fields, and the convergence type was analyzed for each publisher. The results of this study are as follows. First, the total frequencies of STEAM elements and the ratios of each element in the creative and convergent activities of textbooks were different for each publisher. However, among the four elements except for science (S) element in all publishers, the tendency to have a high proportion of art (A) element and a very low proportion of mathematics (M) element was common. Second, the higher the number of fused STEAM elements, the lower the rate of appearance in the textbooks in overall. Also the ratio of convergence types of STEAM elements varied by each publisher. Third, the ratio deviations of art (A), technology (T), and engineering (E) elements for each grade-semester were not large, but the ratio deviation of the mathematics (M) element was large. Fourth, technology (T) and engineering (E) elements appeared a lot in the fields of 'movement and energy' and 'material', while art (A) element appeared a lot in the fields of 'earth and universe', 'life', and 'integration'.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.381-386
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• 2022

Non-Destruction Test (NDT) is a method to check internal defects without destroying the product. Among them, radiographic testing (RT) uses high-energy radiation, so it is very important to prevent radiation exposure of workers. Therefore, in this study, in this study, a radiation sensor structure that improves radiation detection performance compared to the existing PbI₂ and can immediately detect accidents in RT was presented. For evaluation, the conversion efficiency was analyzed in the gamma ray source through FLUKA simulation. PbI₂ with overlapping Gd₂O₂S:Tb presented in this study showed a higher radiation sensitivity from 1.22 to 3.22 times than that of non-overlapping PbI₂. This indicates that the presented sensor is suitable for use as a radiation sensor for source detection in RT.

• Journal of Nutrition and Health
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• v.55 no.5
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• pp.558-571
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• 2022

Purpose: The purpose of this study was to analyze the dietary intake of Korean adults with atopic dermatitis (AD) to determine whether the risk of developing AD was related to their diet. Methods: Among the participants in the 7th National Health and Nutrition Survey (2016 to 2018), 10,571 adults aged 19-64 were divided into AD (AD group, n = 366) and control groups (non-AD group, n = 10,205) to compare and analyze their nutrient intake status and Korean Healthy Eating Index (KHEI) score. Depending on the prevalence of AD, the nutrient intake, nutrient intake per 1,000 kcal, acceptable macronutrient distribution range, and KHEI score were tested for significance by correcting for age, sex, body mass index, education, marriage, occupation, residence area, physical activity, and energy intake variables that were derived for confounding factors. Results: The acceptable macronutrient distribution range for protein was lower in the AD group than in the non-AD group. Comparing the nutrient intake per 1,000 kcal, the intakes of protein, phosphorus, iron, and potassium of the AD group were significantly lower than those of the non-AD group. In the KHEI, the scores of total vegetables, vegetables excluding kimchi and pickles, meat, fish, eggs, and legumes of the AD group were significantly lower than those of the non-AD group. In addition, as these food intake scores increased, the risk of AD significantly decreased. Conclusion: In conclusion, adult AD patients had low intakes of vegetables, meat, fish, eggs, and legumes, and it was confirmed that high intakes of these foods may be associated with low AD risk. Therefore, we suggest that an adequate intake of vegetables and foods containing protein would be necessary for the management and treatment of AD in adults.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.75-82
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• 2023

The purpose of this study was to investigate listener's affective responses to different vocal registers and modes in terms of valence (i.e., negative to positive affect) and arousal (i.e., low to high energy level). The data were collected from four different conditions (i.e., higher and lower registers paired with major and minor modes). A total of 188 female college students participated in the survey online and rated their perceived valence and arousal levels on a visual analogue scale after listening to each excerpt. The two-way analysis of variance (ANOVA) was administered for data analysis. The results revealed that there were significant differences in the affective responses to the two vocal registers, showing that the arousal was more affected by the register than the valence. Secondly, mode had statistically significant impact on both valence and arousal while weighing more on valence. Further, there was significant interaction effect of vocal register and mode on valence, but not on arousal. Results also displayed that listeners had the most negative valence when listening to the excerpt of minor mode in higher register, while having the lowest arousal when listening to the excerpt of minor mode in lower register. These findings imply that it is important to consider the vocal range as well as the musical mode when selecting music for appreciation.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.42-50
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• 2023

In this study, hexagonal ferrite powder with chemical formula SrZn_2-xCo_xFe₁₆O₂₇ was synthesized by a solid-state reaction method and its electromagnetic (EM) wave absorption characteristics were evaluated in the frequency range of 0.1-18 GHz with absorber thickness range of 0 - 10 mm. Reflection loss (RL) affecting electromagnetic wave absorption performance was calculated based on the transmission line theory using measured complex permeabilities and permittivities. RL spectra were also directly measured for some samples. They were well matched with calculated results. High-frequency complex permeability characteristics were changed gradually according to the amount of Co substitution (x). The EM wave absorption frequency band could be tuned accordingly. Hexaferrite samples with x = 1.0, 1.25, and 1.5 exhibited remarkable maximum electromagnetic wave absorption performances with minimum RL (RL_min) lowered than -50 dB. They also showed a very broad frequency band (Δf > 10 GHz) in which more than 90% of the EM wave energy absorption occurred (RL ≤ -10 dB).

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.15-25
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• 2023

The effects of forest fires on the activity of microbial communities in topsoil and subsoil were investigated. Samples were collected from Korean forest soils comprising mainly igneous and sedimentary rocks. Analysis of beta-glucosidase, found higher microbial activity in sedimentary rocks than in igneous rocks. Enzyme activity was not observed immediately after fire, but was restored over time. The enzyme activity of subsoil was inhibited by 33~46% compared with that in the topsoil, regardless of soil damage. The effect of fire on the availability of microbial substrate was investigated using EcoPlate. The percentages of average well color development values of damaged and normal topsoil were 52.7~56.8% and 62.3~83.6%, respectively. Forest fires appear to affect the diversity and substrate availability of the subsoil microbial community by accelerating the decomposition of soil organic matter. The Shanon index, representing microbial biodiversity, was high in the topsoil of all samples; it was higher for soil microorganisms in sedimentary rocks than in igneous rocks, and higher in topsoil than in subsoil.

• Journal of radiological science and technology
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• v.45 no.6
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• pp.523-529
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• 2022

Gamma spectroscopy analysis is widely used for radioactivity analysis, and various factors are required for radioactivity calculations. Among the factors, K3 for each sample significantly influences the results. The previous methods of correcting the self-absorption effect include a computational simulation method and a method that requires making a CRM(certified reference material) identical to the sample medium. However, the above methods have limitations when used in small institutions because they require specialized program utilization skills or high manufacturing costs and large facilities. The aim of this study is to develop a method that can be easily and rapidly applied to radioactivity analysis. After filling the beaker with water, we placed the radiation source in a uniform position and used the measured value as the benchmark. Next, a correction factor was derived based on the difference in the radiation source count of the benchmark and the identically measured sample. For the radiation source, Eu-152, which emits a broad range of energy within the measurement range of gamma rays, and Cs-134 and Cs-137, which are indicator nuclides in environmental radiation analysis, were used. The sample was selected within the density range of 0.26-2.11 g/cm³, and the correction factor was derived by calculating the count difference of each sample compared to the reference value of water. This study presents a faster and more convenient method than the existing research methods for determining the self-absorption effect correction, which has become increasingly necessary.

• Membrane Journal
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• v.33 no.4
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• pp.149-157
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• 2023

Covalent organic frameworks (COFs) have shown promise in various applications, including molecular separation, dye separation, gas separation, filtration, and desalination. Integrating COFs into membranes enhances permeability, selectivity, and stability, improving separation processes. Combining COFs with single-walled carbon nanotubes (SWCNT) creates nanocomposite membranes with high permeability and stability, ideal for dye separation. Incorporating COFs into polyamide (PA) membranes improves permeability and selectivity through a synthetic interfacial strategy. Three-dimensional COF fillers in mixed-matrix membranes (MMMs) enhance CO₂/CH₄ separation, making them suitable for biogas upgrading. All-nanoporous composite (ANC) membranes, which combine COFs and metal-organic framework (MOF) membranes, overcome permeance-selectivity trade-offs, significantly improving gas permeance. Computational simulations using hypothetical COFs (hypoCOFs) demonstrate superior CO₂ selectivity and working capacity relevant for CO₂ separation and H₂ purification. COFs integrated into thin-film composite (TFC) and polysulfonamide (PSA) membranes enhance rejection performance for organic contaminants, salt contaminants, and heavy metal ions, improving separation capabilities. TpPa-SO₃H/PAN covalent organic framework membranes (COFMs) exhibited superior desalination performance compared to traditional polyamide membranes by utilizing charged groups to enable efficient desalination through electrostatic repulsion, suggesting their potential for ionic and molecular separations. These findings highlight COFs' potential in membrane technology for enhanced separation processes by improving permeability, selectivity, and stability. In this review, COF applied for the separation process is discussed.