• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.426-434
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• 2022

Bubbles generated by various causes in the ocean are known to persist for long periods of time. Although the volume occupied by bubbles in the ocean is small, the presence of bubbles in ocean due to resonance and attenuation greatly affects the acoustic properties. Accordingly, bistatic reverberation experiment was performed in the ocean where artificial bubbles exist. A number of transducers and receivers were installed on 6 buoys arranged in a hexagonal shape, and blowing agents were dropped in the center of the buoy to generate bubbles. For reverberation modeling that reflects acoustic characteristics changed by bubbles, the spatial distribution of bubbles was estimated using video data and received signals. A measurement-based bubble spectral shape was used, and it was assumed that the bubble density within the spatial distribution of the estimated bubble was the same. As a result, it was confirmed that the bubble reverberation was simulated in a time similar to the measured data regardless of the bubble density, and the bubble reverberation level similar to the measured data was simulated at a void fraction of about 10^-7 ~ 10^-6.8.

• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.143-148
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• 2022

The subject of this paper is the practical examples of technoculture that critically thinks network technology, a strong material foundation in the era of data capitalism in the 21st century, and appropriates its socio-cultural metaphor as an artistic potential. In order to analyze its alternatives and the meaning of cultural politics, this paper examines the properties and influence of data capitalism after the 2008 global financial crisis, and the cultural and artistic context formed by its reaction. The first case considered in this paper, Furtherfield's workshop, provided a useful example of how citizens can participate in social change through learning and education in which art and technology are interrelated. The second case, Greek hackerspace HSGR, developed network technology as a tool to overcome the crisis by proposing a new progressive cultural commons due to Greece's financial crisis caused by the global financial crisis and a decrease in the state's creative support. The third case, Paolo Cirio's project, promoted a critical citizenship towards the state and community systems as dominant types of social governance. These technoculture cases can be evaluated as efforts to combine and rediscover progressive political ideology and its artistic realization tradition in the context of cultural politics, paying attention to the possibility of signifying practices of network technology that dominates the contemporary economic system.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.17-25
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• 2021

The recent surge in consumption of traditional liquor related to health, the results of analyzing the chemical characteristics and antioxidant activity by creating Kwaha-ju and Baekhwha-chun, which use Godubab as a method of treating glutinous and normal grains, are as follows. Kwaha-ju is mainly made of glutinous rice, 5.21~12.52% alcohol content, 1.07~2.47g/L in reducing sugar content, 3.22~3.77% pH, Baikhwha-chun alcohol content was 3~5%, except for some experimental groups, and pH was low. As a result of the spectrum analysis of traditional liquor, 50% of the experimental group in Baikhwa-chun is located in the negative area of PC1 such as overload, and some amino acids such as lactic acid, isoleucine, and choline are the main ingredients of glucose, xylose, and maltose. Therefore, the chemical properties and antioxidant activity of Kwaha-ju and Baikhwa-chun, which show similar composition ratio of traditional liquor materials, and use them as basic data to identify and manufacture traditional liquor fermentation through mutual analysis.

• Journal of Korea Entertainment Industry Association
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• v.15 no.8
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• pp.457-464
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• 2021

This study is a study on the development of board games using local cultural contents. As a prior study related to this study, basic research on board game development, research on cultural products based on cultural heritage, and storytelling development research using local cultural and tourism resources were considered. Among them, for the main purpose of board games and development process, discussions were conducted on the research methodology of Lee Dae-woong and Oh Seung-taek (2004). As a result, it was possible to successfully proceed with planning meetings, proposal preparation, board game design, board game 3D graphic production process, and prototype development. What is peculiar is that characters (dried persimmons, strawberries, jujube, and salted seafood) containing Nonsan's unique regional characteristics were searched and utilized. In addition, major cultural heritages such as Donamseowon Confucian Academy and Gwanchoksa Temple, designated as Nonsan-si cultural properties, were combined with important treasure hunt contents of board games to enhance interest and education at the same time. The theme of this paper, Nonsan, Finding Lost Treasure, is a new educational alternative that can solve the problems of computer games, and has the advantage of having the nature of community leisure play, not individual play. Based on this board game development research in the future, we intend to expect the results of game production using cultural elements from other regions.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.327-333
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• 2022

In this study, silicon/carbon nanotube/carbon (Si/CNT/C) composites for anode were prepared to improve the volume expansion of silicon used as a high-capacity anode material. Si/CNT were prepared by electrostatic attraction of the positively charged Si and negatively charged CNT and then hydrothermal synthesis was performed to obtain the spherical Si/CNT/C composites. Poly(vinylidene fluoride) (PVDF), polyacrylic acid (PAA), and styrene butadiene rubber (SBR) were used as binders for electrode preparation, and coin cell was assembled using 1.0 M LiPF₆ (EC:DMC:EMC = 1:1:1 vol%) electrolyte and fluoroethylene carbonate (FEC) additive. The physical properties of Si/CNT/C anode materials were analyzed using SEM, EDS, XRD and TGA, and the electrochemical performances of lithium-ion batteries were investigated by charge-discharge cycle, rate performance, dQ/dV and electrochemical impedance spectroscopy tests. Also, it was confirmed that both capacity and rate performance were significantly improved using the PAA/SBR binder and 10 wt% FEC-added electrolyte. It is found that Si/CNT/C have the reversible capacity of 914 mAh/g, the capacity retention ratio of 83% during 50 cycles and the rate performance of 70% in 2 C/0.1 C.

• Journal of Industrial Convergence
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• v.20 no.10
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• pp.169-176
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• 2022

The purpose of this study is to verify the effect of positive psychological capital of fitness center trainers on emotional labor and job ability. For this purpose, as a convenient sampling method, 265 questionnaires were conducted by directly visiting a fitness center in the metropolitan area, and item analysis, validity analysis, reliability analysis, correlation analysis, and multiple regression analysis were applied to the collected data. As a result of the analysis, the following conclusions were obtained. First, in the relationship between positive psychological capital and emotional labor, it exerted a meaningful influence on hope and optimism in deep acting and superficial acting. Next, in the relationship between positive psychological capital and job competency, leadership ability is self-efficacy, hope, management ability is optimism, hope, counseling ability is hope, optimism, self-efficacy, PR ability is self-efficacy, optimism, and program operation ability is optimism. exerted a significant influence on elasticity. In relation to emotional labor and job competency, counseling ability exerted a significant influence only in deep acting, and in leadership ability, management ability, PR ability, and program operation ability, deep acting and surface acting exercised a significant influence. In the future, it is necessary to study the characteristics and properties of trainers as emotional labor and follow-up studies on improvement measures.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.17-23
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• 2022

Using cement as a road subbase is economical, easily modified and supplemented and has excellent road pavement quality control. In addition, cement adheres well to sandy soils without adhesion, and it plays a role of permanently preserving adhesion in viscous soils with adhesion, so it can be widely applied as stable treatment with the advantages of increased strength, reduced compressibility. and improved durability. However, while cement is excellent in terms of strength for a road subbase, the material properties mean that it is difficult to maintain and reinforce when cracks or fractures occur due to dry shrinkage, and the pH increases in the ground due to hexavalent chromium eluting from cement. which can cause environmental problems such as groundwater contamination. Therefore, this study evaluates the usability of alternatives in the road base layer such as environmentally cementitious stabilizer and on-site soil generated from the site. We intend to reduce the environmental damage and evaluate the durability. To evaluate the applicability of the site, Environmental stability test and freeze-thaw test and wetting-drying test was conducted to evaluate the strength characteristics of alternative materials on the road through the limited performance evaluation of environmentally cementitious stabilizer. The test ranges were set at mixing ratios of 10%, 20%, and 30% and ages of three days, and 28 days old to evaluate the early strength and reference strength according to the mixing ratio of the environmentally cementitious stabilizer.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.935-941
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• 2022

The purpose of this study was to investigate whether the activity of ginsenoside metabolites and the intestinal immunity antioxidant activity were remarkably improved by lactic acid bacteria fermentation by adding a small amount of ginsenoside to the complex extracts of fruits and vegetables. It was confirmed that the increase in intestinal immunity antioxidant activity due to synergistic effect was observed in the fruit-vegetable extract containing ginsenoside compared to the ginsenoside-only extract or the fruit-vegetable extract. Then, by adding ginsenosides by content, the concentration of ginsenosides that can obtain a synergistic effect according to the fermentation of lactic acid bacteria was determined. As a result, it was confirmed that a synergistic effect was exhibited when lactic acid bacteria were fermented and extracted by mixing ginsenosides in a mass ratio of 3 to 10% with respect to the mass of the fruit-vegetable mixture. As a result, when treated at a concentration of 200 ㎍/ml, the fruit-vegetable complex extract containing ginsenoside metabolites inhibited the generation of NO by about 60% compared to the complex extract containing no ginsenoside, The expression of IL-1β was suppressed by 63%, the expression of IL-6 by 69%, and the expression of TNF-α by 76%, confirming that the intestinal immune antioxidant properties were significantly improved.

• Journal of Adhesion and Interface
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• v.23 no.4
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• pp.122-129
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• 2022

In this study, the hydrophilicity of the metal fiber is improved by introducing an oxygen-containing functional group to the fiber surface after treatment of the metal fiber using the oxygen plasma treatment time as an experimental variable. For the surface modification of metal fibers, changes in surface properties before and after plasma treatment were observed using SEM and x-ray photoelectron spectroscopy (XPS). In order to observe the effect of the plasma treatment time on the surface of the metal fiber, the change in contact angle of the metal fiber with respect to a polar solvent and a non-polar solvent was measured. After calculating the change in surface free energy using the measured contact angle, the contact angle and the surface free energy for metal fibers before and after oxygen plasma treatment were compared, and the correlation with the adhesion work was also considered. The microdroplet specimens were prepared to investigate the effect of surface changes of these metal fibers on the improvement of shear strength at the interface when combined with other materials and the interfacial shear strength was measured, and the correlation with the adhesion work was also identified. Therefore, the oxygen plasma treatment of the metal fiber results in an increase in the physical surface area on the fiber surface and a change in contact angle and surface energy according to the introduction of the oxygen-containing functional group on the surface. This surface hydrophilization resulted in improving the interfacial shear strength with the polymer resin.

• Geophysics and Geophysical Exploration
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• v.26 no.3
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• pp.114-125
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• 2023

The physics-informed neural network (PINN) has been proposed to overcome the limitations of various numerical methods used to solve partial differential equations (PDEs) and the drawbacks of purely data-driven machine learning. The PINN directly applies PDEs to the construction of the loss function, introducing physical constraints to machine learning training. This technique can also be applied to wave equation modeling. However, to solve the wave equation using the PINN, second-order differentiations with respect to input data must be performed during neural network training, and the resulting wavefields contain complex dynamical phenomena, requiring careful strategies. This tutorial elucidates the fundamental concepts of the PINN and discusses considerations for wave equation modeling using the PINN approach. These considerations include spatial coordinate normalization, the selection of activation functions, and strategies for incorporating physics loss. Our experimental results demonstrated that normalizing the spatial coordinates of the training data leads to a more accurate reflection of initial conditions in neural network training for wave equation modeling. Furthermore, the characteristics of various functions were compared to select an appropriate activation function for wavefield prediction using neural networks. These comparisons focused on their differentiation with respect to input data and their convergence properties. Finally, the results of two scenarios for incorporating physics loss into the loss function during neural network training were compared. Through numerical experiments, a curriculum-based learning strategy, applying physics loss after the initial training steps, was more effective than utilizing physics loss from the early training steps. In addition, the effectiveness of the PINN technique was confirmed by comparing these results with those of training without any use of physics loss.