• Journal of Technologic Dentistry
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• v.43 no.4
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• pp.186-193
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• 2021

Purpose: The purpose of the study was to determine the general characteristics of students in dental technology departments; the correlations among their immersion in learning, class satisfaction, and academic achievement; factors influencing online learning experience; ways to improve students' class satisfaction; and basic data for designing effective online courses. Methods: A total of 300 questionnaires were produced and distributed to dental technology students from September 29 through October 8, 2020. The outcome was analyzed using IBM SPSS Statistics ver. 25.0. A significance level of α=0.05 was used for reliable verification. Results: Immersion in learning, class satisfaction, and academic achievement were relatively high among students who studied on a regular basis, and class satisfaction and academic achievement were relatively high among students who studied with almost no interruption. Concerning the correlations between academic achievement, immersion in learning, and class satisfaction in online learning, the correlation between academic achievement and class satisfaction was the highest at r=0.862. Class satisfaction was the largest factor that influenced academic achievement, and the higher students' immersion in learning and class satisfaction were, the higher their academic achievement was. Conclusion: The research is a case study that investigated the general characteristics of dental technology department students and the correlations among their immersion in learning, class satisfaction, and academic achievement. The study outcome could be used in determining factors that influence online learning and designing effective online courses that improve learner satisfaction.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.475-481
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• 2000

The purpose of this study was to evaluate the effect of oral environment on the strength of resin bracket wings by comparing fracture mode according to water immersion and thermocycling. Seventy-five resin brackets(Spirit MB, Ormco, California) were divided into three groups and treated for six months as follows; (1) untreated, (2) water immersion in distilled water at $37^{\circ}C$, (3) water immersion in distilled water at $37^{\circ}C$ with total 2,100 times of thermocycling taken 350 times each month. Fracture mode of the wing was tested on universal testing machine. In addition to resin brackets, 25 metal brackets were used as controls. Through the statistical analyses, following results were obtained. 1. Resin bracket wings showed significantly lower fracture strength than metal brackets(p<0.001). 2. Water immersion and water immersion with thermocycling groups showed significantly lower fracture strength than open air condition group(p<0.001). 3. Water immersion with thermocycling group showed significantly lower fracture strength than water immersion group(p<0.001). The above results suggest that the mechanical property of resin bracket wing nay be influenced by oral environment and further research is needed to improve the strength of the wing in the resin bracket.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.253-261
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• 2000

Head-out water immersion induces marked increase in the cardiac stroke volume. The present study was undertaken to characterize the stroke volume change by analyzing the aortic blood flow and left ventricular systolic time intervals. Ten men rested on a siting position in the air and in the water at $34.5^{circ}C$ for 30 min each. Their stroke volume, heart rate, ventricular systolic time intervals, and aortic blood flow indices were assessed by impedance cardiography. During immersion, the stroke volume increased 56%, with a slight (4%) decrease in heart rate, thus cardiac output increased ${\sim}50%.$ The slight increase in R-R interval was due to an equivalent increase in the systolic and diastolic time intervals. The ventricular ejection time was 20% increased, and this was mainly due to a decrease in pre-ejection period (28%). The mean arterial pressure increased 5 mmHg, indicating that the cardiac afterload was slightly elevated by immersion. The left ventricular end-diastolic volume index increased 24%, indicating that the cardiac preload was markedly elevated during immersion. The mean velocity and the indices of peak velocity and peak acceleration of aortic blood flow were all increased by ${\sim}30%,$ indicating that the left ventricular contractile force was enhanced by immersion. These results suggest that the increase in stroke volume during immersion is characterized by an increase in ventricular ejection time and aortic blood flow velocity, which may be primarily attributed to the increased cardiac preload and the muscle length-dependent increase in myocardial contractile force.

• Resources Recycling
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• v.30 no.1
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• pp.60-65
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• 2021

The recycling of titanium turning scraps requires the removal of cutting oil and other contaminants remaining on the surface. In this study, an experiment was conducted in which titanium scraps were cleaned by a combination of ultrasonic immersion-steam cleaning and subsequent drying at high temperature. To determine the removal mechanism of cutting oil, the contact angle between titanium surface and cutting oil was measured. The result confirmed the optimum condition of the immersion solution of the titanium turning scraps. In the case of immersion cleaning of Na4P2O7 aqueous solution, the degree of carbon removed in the cutting oil was the highest at 50℃, and it was confirmed that the carbon content obtained from the combination of steam cleaning and ultrasonic immersion-steam cleaning was lower than that from steam cleaning after ultrasonic immersion. The oxidation and decomposition behaviors of cutting oil were investigated using Thermogravimetric analysis (TGA) and the result was applied in the high temperature drying process. From the results of the high temperature drying tests, it was concluded that 200℃ is the optimal drying temperature.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.35-50
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• 2024

This study was attempted to determine the effect of premenstrual syndrome, menstrual pain, attitudes toward menstruation, and quality of sleep on learning immersion in female college students. The subjects of the study were 166 female college students at C University in Gyeongsangnam-do, and data collection was conducted from July 01 to August 31, 2023, using a Google questionnaire. The collected data were analyzed by correlation, multiple regression analysis. Premenstrual syndrome had a significant positive correlation with attitudes toward menstruation(r=.40, p<.001) and menstrual pain(r=.33, p<.001). And sleep quality had a significant positive correlation with menstrual pain(r=.31, p<.001) and learning immersion(r=.24, p=.002). Variables that have a significant impact on learning immersion include 'irregularity in eating' (β =.20, p=.007), 'abdominal massage' to relieve menstrual pain (β=.27, p=.003), and sleep quality (β=.16, p=.038). 'Abdominal massage' to relieve menstrual pain was found to be the best predictor of learning immersion, followed by 'irregularity in eating' and sleep quality. The total explanatory power was 13.9%. Based on the above results, in order to increase learning commitment through mitigation of premenstrual syndrome, education is necessary to seek active countermeasures by increasing various treatments and interest in them, and to have a positive attitude toward menstruation by having proper eating habits.

• Journal of Digital Convergence
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• v.19 no.7
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• pp.341-348
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• 2021

This study identified learners' immersion, focusing on online video education platforms, Zoom and Webex, used in colleges after the 'Covid-19', and suggested design improvement measures to improve immersion. Through prior research and literature research, the components of immersion and screen components of the online distance education platform were identified, and measures to improve immersion were suggested through questionnaire surveys and in-depth interviews. The research method was conducted for 5 days from April 7 to 12, 2021 for 50 college students and graduate students in their 20s and 30s who are receiving online education through Zoom and Webex, and 6 people were interviewed in-depth. As a result of the experiment, the communication between learners and lecturers was deduced as the biggest factor, so a design plan to facilitate communication between learners and lecturers was proposed based on Gutenberg's diagram. As online video education is predicted to continue even after the Covid-19, continuous online video education immersion research is needed, and we hope that it can contribute to the direction of the research.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.1
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• pp.93-113
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• 2022

Among Korea's content industries, the game industry is growing in size to the extent that it can be said to be a representative export-benefiting industry. Accordingly, many users are immersed in the game, and furthermore, they are addicted. This study aims to derive factors for social game users to continue to use by identifying the factors of domestic social network game users' attachment to social network games and empirically studying the causal relationship between these factors and the intention to continue to use them through immersion and addiction. To this end, a research model was presented that applies the main variables of the attachment theory of social network game users to games. The research model of this study surveyed general college students at S University in Seoul who tended to use social network games. As a result of the study, first, it was found that perceived stability had a significant effect on immersion and addiction. Second, it was found that perceived avoidance had a significant effect on immersion and did not have a significant effect on addiction. Third, perceived anxiety was found to have a significant effect on immersion, and it was found that it did not significantly affect addiction. Fourth, it was found that immersion did not significantly affect addiction, and it was found that it had a significant effect on continuous use intention. Fifth, addiction was found to have a significant effect on the intention to continue use. Through this, social network game users' attachment to games can provide useful implications for social network game companies to become attached to existing consumers, spreading social network game users, and improving the possibility of continuous use.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1066-1072
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• 1999

The physical properties of polymer concrete were investigated for development of high-performance construction materials. Various specimens of polymer concrete were prepared using unsaturated polyester resin as the polymer-binder with the various dosage of calcium carbonate as microfiller (5~20 wt %) and fine aggregate(10~50 wt %). For the evaluation of the physical properties of polymer concretes, tests such as compressive strength, flexural strength, water absorption test, hot water immersion test, acid resistance test and pore size distribution analysis were conducted. As a result, it is concluded that compressive and flexural strengths of polymer concretes increased up to 4 times than those of conventional cement concrete. Whereas the compressive and flexural strengths of polymer concretes tested after hot water immersion, compared with those of polymer concretes tested before hot water immersion, decreased about 67%, 47%, respectively. By hot water immersion, total pore volume and porosity(%) of polymer concretes were remarkable increased due to decomposition of polymer binder. And also, it is showed that water absorption(%) and weight loss(%) of polymer concrete specimens by acid immersion, compared with those of ordinary portland cement concrete, decreased about 1/100, 1/27, respectively.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.2
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• pp.436-448
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• 1997

Topical fluoride application for children is a widely performed procedure in the field of Pediatric Dentistry for its dental caries prevention effects. However, it is recently recognized as having some unwanted effects on several esthetic restorative materials as it roughens the surfaces of the restorative materials. In order to evaluate the surface changes in esthetic restorative materials, the author immersed composite resin, glass ionomer cement, and resin-modified glass ionomer cement specimens in various topical fluoride agents and measured the weight loss and also, examined the specimens under the scanning electron microscope. The followings are the results : 1. All the specimens immersed in APF gel for 4 minutes showed statistically significant weight loss. (paired t-test, P<0.05). 2. There was no statistically significant weight loss for the resin-modified glass ionomer cement and composite resin groups immersed in sodium fluoride solution (paired t-test, P>0.05). 3. When the glass ionomer cement group was immersed in APF gel for 1 and 4 minutes, there was a statistically significant weight loss compare to other esthetic restorative materials (ANOVA, P<0.05). 4. In the resin-modified glass ionomer cement group and the composite resin group, weight loss in the APF gel 4 minutes immersion group was greater than the 1 minute immersion group, and it was statistically significant (ANOVA, P<0.05). 5. When the specimens were examined under scanning electron microscope, the surface changes were greatest in the order of glass ionomer cement, resin-modified glass ionomer cement, composite resin and also in the order of APF gel 4 minute immersion group, 1 minute immersion group, sodium fluoride immersion group, and control group.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.3127-3137
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• 2018

The study has been focused on identifying the impact of professors' types of leadership on major satisfaction, learning immersion in college students. To achieve this goal, the results of a survey of 543 affiliated students from september 2017 to november were as follows. Data processing has been done using the IBM SPSS statistics 25 program, and t-test and multi-return analysis were performed to determine the characteristics of the survey subjects, to verify the validity and reliability of the survey tools, and to identify differences and influence between factors. First, there was a difference between gender and grade, but by major, there was no difference. Second, learning immersion varies by major, gender and grade. Third, the factors that significantly influence a type of leadership's satisfaction with a major were shown to have a significant impact on vision and sense of duty, individual consideration, situational reward but were not significant in exceptional control by exception. Fourth, the impact of the types of leadership on learning immersion showed that vision and sense of duty, and situational reward, but individual consideration and exceptional control by exception were not significant.