• Journal of The Korean Association For Science Education
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• v.43 no.3
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• pp.209-223
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• 2023

This study was conducted to evaluate the effectiveness of a polar literacy education program for elementary and middle school students, and to derive implications for new education to respond to climate change. We developed modular education programs based on the seven principles of polar literacy established by the Polar-ICE team. We divided them into two courses, one emphasizing science concepts and another emphasizing humanities and sociological issues. We then selected and structured detailed programs suitable for the two courses. These two courses were applied to 26 elementary and middle school students for approximately 69 hours in a Saturday science class hosted by the Department of Science Education at a university in Seoul. The 26 students were divided into three groups. Two groups completed the science education program for polar literacy and a humanities and social studies education program for polar literacy, respectively. The third group, the control group, received general science education unrelated to polar literacy. Before and after running the programs, all three groups responded to a polar literacy test and questionnaires that used vocabulary and presented scenes associated with polar regions. The test results were expressed using Wilcoxon signed ranks, which is a non-parametric test method, and improvements made upon completion of the program were analyzed. From a cognitive aspect, all three groups showed improvement after completing the program in the knowledge area; however, the experimental groups showed a greater degree of improvement than the control group, and there was a clear difference in the contents or materials explicitly covered. From an affective aspect, the difference between before and after the program was minor, but the group that focused on humanities and social issues showed a statistically significant improvement. Regarding changes in polar imagery, the two experimental groups tended to diverge from monotonous images to more diverse images compared to the control group. Based on the above results, we suggested methods to increase the effectiveness of polar literacy education programs, the importance of polar literacy as appropriate material for scientific thinking and earth system education, measures to improve attitudes related to the polar region, and the need to link to school curriculums.

• Journal of Korean Academy of Dental Administration
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• v.5 no.1
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• pp.22-30
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• 2017

Objective: The purpose is to study the factors to impact on the satisfaction of field practice among dental hygiene students and to provide the basic data for the quality improvement of the field practices for dental hygiene students. Methods: A self-reported questionnaires were filled out by 108 dental hygiene students in C city. Questionnaires were composed with the general characteristics, satisfaction to major, and satisfaction to field clinical practice. The data was analyzed by chi-square statistics using SPSS 20.0 program. Results: The higher satisfaction to communication with professor or seniors in department was associated with the higher satisfaction to field clinical practice (p<0.05). The higher satisfaction to field clinical practice hours per week was associated with the higher satisfaction to field clinical practice (p<0.05). The higher interest to major subjects and the satisfaction to the laboratory environment were associated with the higher satisfaction to field clinical practice (p<0.05). Conclusions: The higher satisfaction to major was associated with the higher satisfaction to field clinical practice. Therefore, the systematic curriculum development is needed to improve the satisfaction with major and clinical practice.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.179-188
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• 2023

Purpose. The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength of two types of zirconia (3-TZP and 5Y-PSZ) with resin cement. Materials and methods. Two different types of zirconia specimens with a fully sintered size of 14.0×14.0×2.0 mm³ were prepared, polished with 400, 600, and 800 grit silicon carbide paper, and buried in epoxy resin. They were classified into four groups each control, sandblasting, primer, and sandblasting & primer. Cylindrical resin adhered to the surface-treated zirconia with resin cement. It was stored in distilled water (37℃) for 24 hours, and a shear bond strength test was performed. The normality of the experimental group was confirmed with the Kolmogorov-Smirnov & Shapiro-Wilk test. The interaction and statistical difference were analyzed using a two-way ANOVA. A post-hoc analysis was performed using Dunnett T3. Results. As a result of two-way ANOVA, there was no significant difference in shear bonding strength between zirconia types (P > .05), but there was a significant correlation in the sandblasting, primer, and alumina sandblasting & primer group (P < .05). Dunnett T3 post-test showed that, regardless of the type of zirconia, shear bonding strength was sandblasting & primer > Primer > sandblasting > control group (P < .05). Conclusion. There was no difference in shear bond strength between the types of zirconia. The highest shear bond strength was shown when the mechanical and chemical treatments of the zirconia surface was performed simultaneously.

• Journal of Marine Life Science
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• v.8 no.2
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• pp.104-114
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• 2023

As plastic usage increases globally, the amount of plastic waste entering the marine environment is steadily rising. Microplastics, in particular, can be ingested by marine organisms and accumulated in their digestive tracts, causing harmful effects on their growth and reproduction. Cytochrome P450 (CYP) enzymes are known to metabolize various environmental pollutants as detoxification enzymes, but their role in crustaceans is not well understood. In this study, sequences of nine CYP genes (CYP370A4, CYP370C5 from clan 2; CYP350A1, CYP350C5, CYP361A1 from clan 3; CYP4AN-like, CYP4AP2, CYP4AP3, CYP4C33-like1 from clan 4) were analyzed using conserved domains in the brackish water flea Diaphanosoma celebensis. Additionally, after exposure to three different sizes of polystyrene beads (0.05-, 0.5-, 6-㎛ PS beads; 0.1, 1, and 10 mg/L) for 48 hours, the expression of these nine CYP genes were investigated using real-time reverse transcription polymerase chain reaction (RT-PCR). The results showed that all CYP genes possessed conserved motifs, indicating that D. celebensis CYP has evolutionarily conserved functions. Among these CYP genes, the expression of CYP370C5, CYP360A1, and CYP4C122 showed a significant increase after exposure to 0.05-㎛ PS beads, suggesting their involvement in PS metabolism. This research will contribute to understanding the molecular mode of actions of microplastics on marine invertebrates.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.775-784
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• 2023

With the increasing trend of extreme rainfall that exceeds the design frequency of man-made structures due to extreme weather, it is necessary to review the safety of agricultural reservoirs designed in the past. However, there are no local government-managed reservoirs (13,685) that can be discharged in an emergency, except for reservoirs over a certain size under the jurisdiction of the Korea Rural Affairs Corporation. In this case, it is important to quickly deploy a mobile siphon to the site for preliminary discharge, and this study evaluated the applicability of a mobile siphon with a diameter of 200 mm, a minimum water level difference of 6 m, 420 (m²/h), and 10,000 (m²/day), which can perform both preliminary and emergency discharge functions, to the Yugum Reservoir in Gyeongju City. The test bed, Yugum Reservoir, is a facility that was completed in 1945 and has been in use for about 78 years. According to the hydrological stability analysis, the lowest height of the current dam crest section is 27.15 (EL.m), which is 0.29m lower than the reviewed flood level of 27.44 (EL.m), indicating that there is a possibility of lunar flow through the embankment, and the headroom is insufficient by 1.72 m, so it was reviewed as not securing hydrological safety. The water level-volume curve was arbitrarily derived because it was difficult to clearly establish the water level-flow relationship curve of the reservoir since the water level-flow measurement was not carried out regularly, and based on the derived curve, the algorithm for operating small and medium-sized old reservoirs was developed to consider the pre-discharge time, the amount of spillway discharge, and to predict the reservoir lunar flow time according to the flood volume by frequency, thereby securing evacuation time in advance and reducing the risk of collapse. Based on one row of 200 mm diameter mobile siphons, the optimal pre-discharge time to secure evacuation time (about 1 hour) while maintaining 80% of the upper limit water level (about 30,000 m²) during a 30-year flood was analyzed to be 12 hours earlier. If the pre-discharge technology utilizing siphons for small and medium-sized old reservoirs and the algorithm for reservoir operation are implemented in advance in case of abnormal weather and the decision-making of managers is supported, it is possible to secure the safety of residents in the risk area of reservoir collapse, resolve the anxiety of residents through the establishment of a support system for evacuating residents, and reduce risk factors by providing risk avoidance measures in the event of a reservoir risk situation.

• Journal of The Korean Association For Science Education
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• v.28 no.5
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• pp.495-505
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• 2008

The purpose of this study was to analyze the level of evidence used in gifted elementary students' argumentation. The subjects were 15, 5th and 6th grade students selected in the Science Education Institute for Gifted Youth in K University. After the argumentation task was given to students 2 weeks ago, the students grouped themselves in the affirmative and negative and took part in a debate for 2 hours. Their argumentation process was observed, recorded and transcribed for analysis. Transcribed data was given a Protocol Number according to priority and was examined to find out what were the characteristics when students participated in the task. The evidence used in argumentation was graded from level 1 to level 6 according to Perella's Hierarchy of Evidence and the rate of frequency classified by the level was expressed in graph. Students used Level 1- Level 2 evidence above 50% without for or against task. They had weak argumentation making use of low-level evidence such as individual experience, opinion and another person's experience rather than objective evidences. On the other hand, students commented on the lack of opponent's evidence when they could not trust an opponent's evidence. If one team asked the other to present more evidence but could not, they disregarded the question and turned to another topic. And in cases where the opponent team refuted with evidences of high level, the other team just repeated their claim or evaded the rebuttal. The students tended to complete the argument without the same conclusions with some interruptions. The results show that we need an educational programs including scientific argumentation for science-gifted elementary school students.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.55-63
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• 2024

Purpose: This study aimed to assess the antimicrobial efficacy of an 810-nm infrared diode laser with indocyanine green (ICG) against Staphylococcus aureus on sandblasted, large grit, and acid-etched (SLA) titanium surfaces, comparing its effectiveness with alternative chemical decontamination modalities. Materials and Methods: Biofilms of S. aureus ATCC 25923 were cultured on SLA titanium disks for 48 hours. The biofilms were divided into five treatment groups: control, chlorhexidine gluconate (CHX), tetracycline (TC), ICG, and 810-nm infrared diode laser with ICG (ICG-PDT). After treatment, colony-forming units were quantified to assess surviving bacteria, and viability was confirmed through confocal laser-scanning microscope (CLSM) imaging. Results: All treated groups exhibited a statistically significant reduction in S. aureus (P < 0.05), with notable efficacy in the CHX, TC, and ICG-PDT groups (P < 0.01). While no statistical difference was observed between TC and CHX, the ICG-PDT group demonstrated superior bacterial reduction. CLSM images revealed a higher proportion of dead bacteria stained in red within the ICG-PDT groups. Conclusion: Within the limitations, ICG-PDT effectively reduced S. aureus biofilms on SLA titanium surfaces. Further investigations into alternative decontamination methods and the clinical impact of ICG-PDT on peri-implant diseases are warranted.

• Journal of agricultural medicine and community health
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• v.28 no.2
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• pp.15-29
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• 2003

Objectives: This study was done to find out fatigue and self-reported physical symptoms of Vinylhouse farmers. The results of this study could be used as a basic data to develop health promotion program for Vinylhouse farmers who are suffering from fatigue and physical symptoms. Methods: The 166 respondents, who were working in Vinylhouse and were living in a remoted area where the primary health post located, were participated in this study. Thirty: 30 items of self-reported fatigue scale was used to evaluate the farmers fatigue level which made by Japanese industrial and hygenic association(1988). Twenty four: 24 items of index used by researcher for self-reported physical symptoms was from Lee In Bae's(1999) modified Index which was originated from Cornell Medical Index(1949). Another questionnaires used in this study were developed by researcher through related documents. Results: The results of this study were as follows; Fatigue scores were high in accordance with women(t=-2.212, p<0.05), worse recognized health state(F=20.610, p<.001), lack of sleeping hours(F=3.937, p<0.05), eat irregularly(t=-3.883, p<0.001), don't take a bath after application of chemical(t=-2.950, p<0.01), working time per a day(F=5.633, p<0.01) & working time per a day in Vinylhouse(F=5.247, p<0.01) were long. Subjective physical symptoms were high in accordance with women(t=-3.176, p<0.01), worse recognized health state(F=35.335, p<0.001), and low education(F=3.467, p<0.05). eat irregularly(t=-3.384, p<0.01), alcohol drinking(t=-2.389, p<0.05). When farmers don't take a bath after application of chemical show high(t=-3.188, p<0.01). As a result, the factors affecting to Vinylhouse worker's health were irregular diet habit, scarce exercise, lack of proper rest, symptoms oriented from Vinylhouse work in contaminated environment with high temperature and humidity. Conclusions: Based on this study, health promotion program is necessary for Vinylhouse workers. Also, the development of continuously practical strategy of healthy life style including exercise and comprehensive health promotion program considered the country's social and cultural background are needed.

• Korean Journal of Agricultural Science
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• v.15 no.1
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• pp.82-94
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• 1988

This study was performed to obtain the basic data which can be applied to use of foaming mortars. The results obtained were summarized as follows ; 1. The lowest water-cement ratios were shown at the mixing ratio of 1 : 1. But, it was gradually increased in poorer mixing ratio and decreased in more addition of foaming agent. The water-cement ratios were decreased up to 1.6-53.1% by mix-foaming type and 4.4-24.1% by pre-foamed type than cement mortar. 2. The highest bulk densities were shown at the mixing ratio of 1 : 1. But, it was gradually decreased in poorer mixing ratio and more addition of foaming agent. The decreasing rates of bulk densities were increased in richer mixing ratio and more addition of foaming agent. 3. The bulk densities were decreased up to 38.8-55.9% by mix-foaming type and 9.7-23.6% by pre-foamed type than cement mortar. 4. The lowest absorption rates were shown at the mixing ratio of 1 : 1. But, it was gradually increased in poorer mixing ratio and more addition of foaming agent. The increasing rates of absorption rates were increased in richer mixing ratio and more addition of foaming agent. 5. Absorption rates when immersed in 72hours were shown up to 3.41-5.85 times greater by mix-foaming type and 1.05-1.55 times greater by pre-foamed type than those of cement mortar. it was significantly higher at the early stage of immersed time than cement mortar. 6. The highest strengths were shown at the mixing ratio of 1 : 1. But, it was gradually decreased in poorer mixing ratio and more addition of foaming agent. The decreasing rates of strengths were increased in poorer mixing ratio and more addition of foaming agent. 7. The strengths were decreased up to 77.0-92.8% by mix-foaming type and 36.7-74.4% by pre-foamed type than cement mortar. 8. The lowest air contents were shown at the mixing ratio of 1 : 1. But, it was gradually increased in poorer mixing ratio and more addition of foaming agent. The increasing rates of air contents were increased in richer mixing ratio and more addition of foaming agent. 9. Air contents were shown up to 26.0-63.8 times greater by mix-foaming type and 5.8-17.7 times greater by pre-foamed type than those of cement mortar. 10. The correlations between bulk density, absorption rate, compressive strength and air content were highly significant. The multiple regression equations of bulk density, absorption rate, compressive strength, tensile strength, bending strength and air content were computed depending on a function of mixing ratio and addition of foaming agent. They were generally highly significant.

• The korean journal of orthodontics
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• v.31 no.5 s.88
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• pp.525-534
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• 2001

Bone remodeling in response to force requires coordinated actions of osteoblasts, osteoclasts, osteocytes, and periodontal ligament cells. Coordination among these cells may be mediated, in part, by cell-to-cell communication via gap junctions. This study was designed to evaluate the expression of gap junction, connection 43 In periodontal tissue during the experimental movement of rat's incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for connexin 43. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats), and 6 experimental groups(24 rats) where 75g of force was applied from helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 12 hours, 1, 4, 7, 14 and 28 days after force application, respectively. And the tissues of a control group and experimental groups were studied immunohistochemically. The results were as follows : 1. In control group, the expression of connexin 43 was rare in gingiva, dentin, cementum, periodontal ligament, and bone cells. 2. In experimental group, the expression of connexin 43 was increased in pulp, periodontal ligament, osteoblasts, and osteoclasts, comparing to that in control. And it was rare in gingiva, dentin, and odontoblasts regardless of the duration of force application, which was not different from that of control group. 3. The expression of connexin 43 in pulp of experimental group began to increase in 4-day after force application and got to the highest degree at 7-day. And it decreased after 14-day to be similar to that of control group at 28-day. 4. The expression of connexin 43 in periodontal ligament was noted in small capillaries adjacent to alveolar bone, showing higher intensity of immunolabelling after 4-day And it was stronger in the pressure side than in tension side of periodontal ligament. After 7-day, decrease in connexin 43 expression was observed. 5. The expression of connexin 43 in alveolar bone began to increase 1-day, reached to the highest degree at 4-day, and decreased at 7-day. And the expression in osteoclasts was more than that in osteoblasts or osteocyte at 7-day.