• Journal of Korean Elementary Science Education
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• v.42 no.1
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• pp.149-160
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• 2023

A Korean-version science curiosity questionnaire (Science Curiosity in Learning Environments [SCILE(15)]) was developed after factor analysis of the Korean-version SCILE(30) questionnaire. Pre-service elementary school teachers were surveyed using the Korean-version SCILE(30), and a factor analysis based on their responses was performed. The factor analysis demonstrated that the Korean-version SCILE(15) consisted of three curiosity factors: a 'science practices' factor, a 'stretching' factor, and an 'embracing' factor. Confirmatory factor analysis of the factor structure revealed correlations between all the factors, thus confirming their commonality as a science curiosity factors. The Cronbach alpha for the reliability of all items in the Korean-version SCILE(15) and of items by factor was greater than 0.700. The Korean-version SCILE(15) was therefore evaluated to be reliable as a science curiosity questionnaire. Pre-service elementary teachers who participated in the survey for the development of the SCILE(15) were aware of the 'science practices', 'stretching', and 'embracing' science curiosity factors. Analysis in a general linear model of the degree of recognition accorded by pre-service elementary teachers to the three science curiosity factors demonstrated significant differences between the curiosity factors in terms of recognition. This cohort of pre-service elementary teachers showed the highest level of recognition of the 'stretching' curiosity factor and the lowest level of recognition of the 'embracing' curiosity factor.

• Journal of the Korean GEO-environmental Society
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• v.24 no.7
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• pp.5-14
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• 2023

Recently, earthquakes have occurred frequently in worldwide. These earthquakes cause various forms of natural and physical damage. In particular, liquefaction in which the ground shows liquid-like behavior causes great damage to the structure. Accordingly, various liquefaction damage reduction methods are being studied and developed. Therefore, in this study, a method of reducing liquefaction damage in the event of an earthquake applicable to existing structures was studied using the sheet pile method. The 1-G Shaking table test was performed and the ground was constructed with Jumunjin standard sand. A two-story model structure was produced by applying the similitude law, and the input wave applied a sine wave with an acceleration level of 0.6 g and a frequency of 10 Hz. The effect of reducing structure damage according to various embedded depth ratio was analyzed. As a result of the study, the structure settlement when the ground is reinforced by applying the sheet pile method is decreased by about 71% compared to when the ground is not reinforced, and the EDR with minimum settlement is "1". In addition, as the embedded depth ratio is increased, the calculation of the pore water pressure in the ground tends to be delayed due to the sheet pile. Based on these results, the relationship with structural settlement according to the embedded depth ratio is proposed as a relational equation with the graph. The results of this study are expected to be used as basic data in developing sheet pile methods applicable to existing structures in the future.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.27-38
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• 2009

In this study, a series of 1 g shaking table model pile tests were carried out in saturated dense and loose sand to evaluate dynamic p-y curves for various conditions of flexural stiffness of a pile shaft, acceleration frequency and acceleration amplitude for input loads. Dynamic p-y backbone curve which can be applied to pseudo static analysis for saturated dense sand was proposed as a hyperbolic function by connecting the peak points of the experimental p-y curves, which corresponded to maximum soil resistances. In order to represent the backbone curve numerically, empirical equations were developed for the initial stiffness ($k_{ini}$) and the ultimate capacity ($p_u$) of soils as a function of a friction angle and a confining stress. The applicability of a p-y backbone curve was evaluated based on the centrifuge test results of other researchers cited in literature, and this suggested backbone curve was also compared with the currently available p-y curves. And also, the scaling factor ($S_F$) to account for the degradation of soil resistance according to the excess pore pressure was developed from the results of saturated loose sand.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.13-22
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• 2008

Fourteen calibration ehamber tests were performed using one cylindrical and two tapered piles with different taper angles to investigate the changes of the bearing capacity of tapered piles with soil state and taper angle of piles. The results of calibration chamber tests show that the ultimate base resistance of tapered piles increases with increasing mean stress and relative density of soil. It also increases with increasing taper angle for medium sand, but with decreasing taper angle for dense sand. The ultimate shaft resistance of tapered piles increases as vertical and horizontal stresses, relative density and taper angle increase. Based on the results of model pile load tests, a new design method with shape factors for estimation of the bearing capacity of tapered piles is proposed considering the effect of soil state and taper angle on bearing capacity of tapered piles. In order to check the accuracy of predictions calculated using the new method, middle-scale field pile load tests were also conducted on cylindrical and tapered drilled shafts in clayey sand. Comparison of calculated values with measured ones shows that the new design method produces satisfactory predictions tor tapered piles.

• Journal of Industrial Convergence
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• v.21 no.4
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• pp.133-143
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• 2023

The purpose of this study is to verify the mediating effect of depression on the effect of forest recreation satisfaction on psychological well-being of customers using forest recreation resources and provide basic data for improving psychological well-being. As for the analysis data, a survey was conducted on 450 customers using forest recreation resources, and the final 355 people were selected as subjects of the survey after removing non-response and insincere responses from 377 copies collected. For analysis, the SPSS WIN 23.0 and Amos 21.0 programs were used, and the mediating effect of depression was verified through descriptive statistical analysis, correlation analysis, and structural model of major variables. The study results showed, first, that forest recreation satisfaction had a negative(-) effect on depression. Second, depression was found to have a negative(-) effect on psychological well-being. Third, depression had a complete mediating effect in the relationship between forest recreation satisfaction and psychological well-being. Based on these results, it is meaningful in that programs and practical and policy suggestions were made to improve psychological well-being.

• Journal of the Korean Society of Safety
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• v.38 no.2
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• pp.96-103
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• 2023

Generally, human stampedes and crowd collapses occur when people press against each other, causing falls that may result in death or injury. Particularly, crowd accidents have become increasingly common since the 1990s, with an average of 380 deaths annually. For instance, in Korea, a stampede occurred during the Itaewon Halloween festival on October 29, 2022, when several people crowded onto a narrow, downhill road, which was 45 meters long and between 3.2 and 4 meters wide. Precisely, this stampede was primarily due to the excessive number of people relative to the road size. Essentially, stampedes can occur anywhere and at any time, not just at events, but also in other places where large crowds gather. More specifically, the likelihood of accidents increases when the crowd density exceeds a turbulence threshold of 5-6 /m². Meanwhile, festivals and events, which have become more frequent and are promoted through social media, garner people from near and far to a specific location. Besides, as cities grow, the number of people gathering in one place increases. While stampedes are rare, their impact is significant, and the uncertainty associated with them is high. Currently, there is no scientific system to analyze the risk of stampedes due to crowd concentration. Consequently, to prevent such accidents, it is essential to prepare for crowd disasters that reflect social changes and regional characteristics. Hence, this study proposes using digital topographic maps and crowd-density risk simulations to develop a 3D model of the region. Specifically, the crowd density simulation allows for an analysis of the density of people walking along specific paths, which enables the prediction of danger areas and the risk of crowding. By using the simulation method in this study, it is anticipated that safety measures can be rationally established for specific situations, such as local festivals, and preparations may be made for crowd accidents in downtown areas.

• Journal of Periodontal and Implant Science
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• v.53 no.2
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• pp.120-134
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• 2023

Purpose: We investigated whether repeated irradiation with light-emitting diodes (LEDs) at a combination of 470 nm and 525 nm could suppress the progression of experimental periodontitis. Methods: A experimental periodontitis model was established in the second, third, and fourth premolars of the mandible in beagle dogs for 2 months. The spontaneous progression of periodontitis was monitored under the specified treatment regimen for 3 months. During this period, the animals were subjected to treatments of either plaque control only (control) or plaque control with LED application (test) at 2-week intervals. The clinical parameters included the probing pocket depth (PPD), gingival recession (GR), and the clinical attachment level (CAL). Histomorphometric analysis was performed using measurements of the length of the junctional epithelium, connective tissue (CT) zone, and total soft tissue (ST). Results: There were significant differences in PPD between the control and test groups at baseline and 12 weeks. When the change in PPD was stratified based on time intervals, it was shown that greater differences occurred in the test group, with statistical significance for baseline to 12 weeks, 6 to 12 weeks, and baseline to 6 weeks. There was no significant difference in GR between the control and test groups at any time points. Likewise, no statistically significant differences were found in GR at any time intervals. CAL showed a statistically significant difference between the control and test groups at baseline only, although significant differences in CAL were observed between baseline and 12 weeks and between 6 and 12 weeks. The proportion of CT to ST was smaller for both buccal and lingual areas in the control group than in the test group. Conclusions: Repeated LED irradiation with a combination of 470-nm and 525-nm wavelengths may help suppress the progression of periodontal disease.

• Knowledge Management Research
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• v.24 no.1
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• pp.31-49
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• 2023

TikTok, as a leading short video platform, has attracted many users, and the resulting attention generates immense business value as a platform to diffuse knowledge. As a qualitative and explorative approach, this study reviews the knowledge payment industry and discusses the influential factors of users' payment decisions regarding knowledge products on TikTok. By conducting in-depth interviews with ten participants and observing 95 knowledge providers' videos, we find that TikTok has significant business potential in the knowledge payment industry. By using the ATLAS. ti software to code the data collected from these interviews, this study finds that demander characteristics (personal needs), product characteristics (product quality), provider characteristics (the key opinion leader effect), and platform characteristics (platform management) are the four core categories that influence users' payment decisions regarding knowledge products on TikTok. A theoretical model consisting of the ten variables of emotional needs, professional needs, quality, price, helpfulness, value, charisma, user trust, service guarantee, and scarcity is proposed based on the grounded theory. The theoretical and practical implications of the study findings are also discussed.

• Knowledge Management Research
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• v.23 no.4
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• pp.133-157
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• 2022

As data becomes a new core resource with high attention, MyData service is spreading to various fields such as finance, medical care, and the public sector. However, research on the behavior of MyData service users is insufficient. Therefore, this study aims to empirically examine the effect of MyData service traits on value perception and acceptable behavior particularly in the financial sector where MyData service is most active. To this end, this study proposed a research model based on the literature. 295 survey responses were collected from individuals and analyzed using AMOS 26.0 for hypothesis testing. As a result of the analysis, it was found that self-information control, financial convenience, and personalized service had a significant effect on perceived value, and that perceived value had a significant effect on the intention to accept MyData service. Furthermore, this study examined the role of personal innovation and technological security in the relationship between variables by suggesting them as moderators. Results show that individual innovation was found to strengthen the relationship between two variables(self-information control and personalized service) and perceived value. Also, technological security was shown to strengthen the relationship between perceived value and intention to accept financial MyData services. The findings are expected to provide useful information to understand the factors affecting the acceptance of financial MyData service users and to understand the importance of individual innovation levels and technological security.

• Knowledge Management Research
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• v.23 no.4
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• pp.207-231
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• 2022

The purpose of this study is to identify the relationship between PJF(person-job fit) and members' organizational commitment focusing on the mediating factor. Previous Studies have found that person-job fit has positive effect on organizational commitment, and self-efficacy has positive effect on the organizational commitment. On the other hand, the studies to identify whether self-efficacy has a role in mediation between PJF and the members' organizational commitment has been insufficient. To that end, we considered self-efficacy as the mediator of the relationship between PJF and organizational commitment. We used the data which to perform national policy research from 690 workers at a small or medium firm. As a result of verifying the suitability of the research model, it was suitable for the acceptance criteria. Besides the hierarchical regression analysis, bootstrapping was conducted to verify significance of mediating effect of self-efficacy. The main results are as follows. First, the variables, PJF, self-efficacy and organizational commitment showed a positive correlation. Second, PJF has a positive effect on self-efficacy and organizational commitment significantly. Also self-efficacy has a positive effect on organizational commitment significantly. Third, the mediating effect of self-efficacy in the relationship between PJF and organizational commitment is significant. In order to improve person-job fit, this study suggested that SMEs' owners should consider job rotation system and career development program for employees. Based on this study result and implications, we discussed limit of research and direction for future research.