• Journal of Industrial Convergence
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• v.20 no.3
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• pp.11-21
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• 2022

The purpose of this study is to provide fundamental background to improve the quality of teaching and learning performance in online classes by analyzing the students' learning experience aspects on online environment. This study explores the relationship between learning experience and teaching and learning performance according to the online classes types(synchronous/asynchronous class), and identifies the mediation effect of students' perception and attitude toward online classes using Structural Equations Model(SEM). The findings are shown as follows: First, learning experience has positive effect on teaching and learning performance statistically. Second, learning experience has different effect on teaching and learning performance depending on the type of online classes. Specifically, learning experience in synchronous environment has higher influence on teaching and learning performance than in asynchronous environment. On the other hand, perception and attitude toward online classes have greater influence on teaching and learning performance in asynchronous class than in synchronous class. Lastly, the students' perception and attitude toward online classes do not have mediation effects significantly in the relationship between learning experience and teaching and learning performance. The result of this study can be a guide for researcher to approach to teaching and learning performance in online environment of university.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.161-169
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• 2022

The purpose of this study performed to confirm the effect of caffeine intake and stress on sleep quality of college students. Research respondents and data collection were conducted on 269 college students through Google questionnaires from February 14 to March 13, 2022, and the research design is a descriptive survey study. Statistical analysis was performed using the SPSS 27.0 version as t-test and one way ANOVA. As a result of the study, it was found that most college students consume more caffeine than the average daily caffeine intake of Korean adults, although it is far below the recommended daily caffeine intake of Korean adults. The quality of sleep of college students is stress (r=.32, p=<).001) and caffeine intake (r=.204, p=.001). It was found that there was a positive correlation. Factors affecting sleep quality are body mass index (β=.1.19, p<.001) Stress (β=.3.37, p<.001), smoking (β=-.18, p=.001), caffeine intake (β=.15, p=.005) It was in order, and the explanatory power of the model was 24.8%.

• 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.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.577-582
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• 2022

Credit transactions are used as a means of price discrimination from competitors in order for suppliers to increase customer demand. In particular, in the case of a two-stage supply chain consisting of a supplier, a retailer, and a customer, the deferral of payment for goods allowed by the supplier is a means of reducing the inventory investment cost of the retailer. Retailers have the opportunity to discount the selling price while anticipating an increase in end-customer demand through the reduction of the inventory investment cost. In view of the fact that such trade credit is provided for the purpose of increasing demand as a means of discrimination from competitors, it may be more general that the credit transaction period is allowed flexibly according to the transaction volume. In particular, in the case of deteriorating products, the credit transaction period given according to the order volume is a factor that increases the order volume of the retailer, but product deterioration can be a limiting factor in the increase in the order volume. The deterioration rate actually plays an important role in determining the inventory policy of the retailer. Therefore, in this paper, the effect of such deterioration rate on the inventory policy of retailer is analyzed.

• Journal of Internet of Things and Convergence
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• v.8 no.3
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• pp.11-20
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• 2022

Corporations operate within long term strategy. The Chief Executive Officer (CEO) makes decisions and has responsibility for all executive activities which affects the corporate performance. If the CEO makes strategic choices through reasonable decision making, it could affect corporate performance and corporate's rise and fall. So the CEO's decision making is very important. As rapid change in the digital technology environment happened, through digital transition, corporations have been working on increasing corporate performance by practical and academic methods. However prior research was restricted to CEO's affect on organization, innovation or innovative activities and there is a lack of research linking CEO's characteristics to digital transition and corporate performance. As the digital age is coming, research on how CEO's characteristics affect digital transition and corporate performance is direly needed. From the case of domestic Big Data corporation RSN Co. ltd's digital transition success, understanding characteristics of CEO, digital transition and corporate performance through prior researches, and developing research model and research proposition was set. Research was performed on RSN co. ltd's case analysis, and how characteristics of CEO's matter on digital transformation and corporate performance. As a result of the proposition, when the CEO conjugates digital technology, the corporation was able to successfully complete digital transition and it also affects corporate performance. Also, this research's other point is that CEO's may have limits on thoughtful decision making. It is judged that it is necessary to try an empirical study in the future.

• Journal of Industrial Convergence
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• v.20 no.8
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• pp.109-118
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• 2022

This study aims to examine the extent of lifestyle behavior changes, perceived restrictions in daily life, and their relationship during the COVID-19 pandemic. Using the 2020 Community Health Survey data, this study calculated perceived restrictions in daily life among adults in Korea during the pandemic by sociodemographic characteristics and lifestyle behavior category (physical activity, sleeping duration, drinking, smoking, social contact, public transport use, food delivery, instant food consumption). The generalized linear model examined the relationship between behavior change and perceived restriction on daily life. A total of 227,808 respondents were analyzed. 56.70% of the population perceived their daily lives restricted by 50% and more during the pandemic. The majority of the population decreased physical activity, social contact, and public transport use (52.71%, 89.70%, and 63.74%, respectively). Individuals who decreased physical activity, sleep duration, and social contact frequency, and those who increased drinking frequency, food delivery, and instant food consumption perceived greater restrictions in daily life than those who did not change respective behaviors (p<0.001). In conclusion, decreases in social contact and physical activity and increases in use of food delivery and instant food consumption were associated with greater perceived restrictions of daily life during the pandemic. Efforts to alleviate the negative impact of the pandemic on psychological well-being may need to involve attempts to improve healthy life behaviors.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.515-524
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• 2022

The turnout system of the sleeper floating tracks (STEDEF) on urban transit is a Anti-vibration track composed of a wooden sleeper embedded in a concrete bed and a sleeper resilience pad under the sleeper. Therefore, deterioration and changes in spring stiffness of the sleeper resilience pad could be cause changes in sleeper support conditions. The damage amount of manganese crossings that occurred during the current service period of about 21 years was investigated to be about 17% of the total amount of crossings, and it was analyzed that the damage amount increased after 15 years of use (accumulated passing tonnage of about 550 million tons). In this study, parameter analysis (wheel position, sleeper support condition, and dynamic wheel load) was performed using a three-dimensional numerical model that simulated real manganese crossing and wheel profile, to analyze the damage type and cause of manganese crossing that occurred in the actual field. As a result of this study, when the voided sleeper occurred in the sleeper around the nose, the stress generated in the crossing nose exceeded the yield strength according to the dynamic wheel load considering the design track impact factor. In addition, the analysis results were evaluated to be in good agreement with the location of damage that occurred in the actual field. Therefore, in order to minimize the damage of the manganese crossing, it is necessary to keep the sleeper support condition around the nose part constant. In addition, by considering the uniformity of the boundary conditions under the sleepers, it was analyzed that it would be advantageous to to replace the sleeper resilience pad together when replacing the damaged manganese crossing.

• Journal of Industrial Convergence
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• v.21 no.1
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• pp.159-165
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• 2023

While the frequency of seismic occurrence has been increasing recently, the domestic seismic response system is weak, the objective of this research is to compare and analyze the seismic vulnerability of buildings using statistical analysis and machine learning techniques. As the result of using statistical technique, the prediction accuracy of the developed model through the optimal scaling method showed about 87%. As the result of using machine learning technique, because the accuracy of Random Forest method is 94% in case of Train Set, 76.7% in case of Test Set, which is the highest accuracy among the 4 analyzed methods, Random Forest method was finally chosen. Therefore, Random Forest method was derived as the final machine learning technique. Accordingly, the statistical analysis technique showed higher accuracy of about 87%, whereas the machine learning technique showed the accuracy of about 76.7%. As the final result, among the 22,296 analyzed building data, the seismic vulnerabilities of 1,627(0.1%) buildings are expected as more dangerous when the statistical analysis technique is used, 10,146(49%) buildings showed the same rate, and the remaining 10,523(50%) buildings are expected as more dangerous when the machine learning technique is used. As the comparison of the results of using advanced machine learning techniques in addition to the existing statistical analysis techniques, in spatial analysis decisions, it is hoped that this research results help to prepare more reliable seismic countermeasures.

• Journal of Intelligence and Information Systems
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• v.29 no.1
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• pp.289-305
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• 2023

The rapid increase in the use of mobile devices is changing consumers' online shopping behavior. However, the difference in the effect on the conversion rate according to the time when consumers switch from a small screen to a large screen has not been sufficiently studied. In addition, the differences in the effect of device conversion on purchase performance according to the characteristics of each country's infrastructure have not been sufficiently studied. Against this background, this study aims to analyze whether the timing of switching from mobile devices to PC devices and the country's mobile Internet penetration rate are moderating the positive effect of device switching on purchase performance. For empirical analysis, Google Merchandise Store data was collected and 101,466 data from 130 countries were analyzed with a multilevel model. As a result of the analysis, consumers' device switching (i.e., mobile to PC) had a positive effect when it occurred in the middle of the consumer journey. However, it was analyzed that when device switching occurred at the later stage of the consumer journey, it had a negative effect on purchase performance. In addition, it was analyzed that the higher the mobile Internet penetration rate, the weaker the positive effect of consumer device conversion on purchase performance.

• BMB Reports
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• v.56 no.3
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• pp.196-201
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• 2023

Renal fibrosis is the final manifestation of chronic kidney disease (CKD) regardless of etiology. Hypoxia-inducible factor-2 alpha (HIF-2α) is an important regulator of chronic hypoxia, and the late-stage renal tubular HIF-2α activation exerts protective effects against renal fibrosis. However, its specific role in progressive renal fibrosis remains unclear. Here, we investigated the effects of the long-term tubular activation of HIF-2α on renal function and fibrosis, using in vivo and in vitro models of renal fibrosis. Progressive renal fibrosis was induced in renal tubular epithelial cells (TECs) of tetracycline-controlled HIF-2α transgenic (Tg) mice and wild-type (WT) controls through a 6-week adenine diet. Tg mice were maintained on doxycycline (DOX) for the diet period to induce Tg HIF-2α expression. Primary TECs isolated from Tg mice were treated with DOX (5 ㎍/ml), transforming growth factor-β1 (TGF-β1) (10 ng/ml), and a combination of both for 24, 48, and 72 hr. Blood was collected to analyze creatinine (Cr) and blood urea nitrogen (BUN) levels. Pathological changes in the kidney tissues were observed using hematoxylin and eosin, Masson's trichrome, and Sirius Red staining. Meanwhile, the expression of fibronectin, E-cadherin and α-smooth muscle actin (α-SMA) and the phosphorylation of p38 mitogen-activated protein kinase (MAPK) was observed using western blotting. Our data showed that serum Cr and BUN levels were significantly lower in Tg mice than in WT mice following the adenine diet. Moreover, the protein levels of fibronectin and E-cadherin and the phosphorylation of p38 MAPK were markedly reduced in the kidneys of adenine-fed Tg mice. These results were accompanied by attenuated fibrosis in Tg mice following adenine administration. Consistent with these findings, HIF-2α overexpression significantly decreased the expression of fibronectin in TECs, whereas an increase in α-SMA protein levels was observed after TGF-β1 stimulation for 72 hr. Taken together, these results indicate that long-term HIF-2α activation in CKD may inhibit the progression of renal fibrosis and improve renal function, suggesting that long-term renal HIF-2α activation may be used as a novel therapeutic strategy for the treatment of CKD.