• Journal of Elementary Mathematics Education in Korea
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• v.14 no.1
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• pp.1-22
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• 2010

The purpose of this study was to examine the relationship between teacher's role and interaction patterns in mathematics classrooms. Teacher's role was divided into usual practices with students, usual practices with content and usual practices with students and contents, and interaction patterns were classified into report, inquiry and discussion. The subjects in this study were teachers and students in three fourth- grade classes in T elementary school located in Seoul. After the classes of every math teacher were observed, three teachers who played distinctively unique roles were selected in accordance with the results of the first-semester autonomous supervision, of open class for parents and of the instructional observation. Thus, there was a close relationship between the teacher roles and interaction patterns. And it's concluded that students are able to have a more discussion on each other's ideas in the student-centered classroom, and that teachers should perform active roles in that process. Given the findings of the study, there are some suggestions: First, the teachers appeared to fulfill consistent roles when their videotaped classes, study aids and performance assessment materials were analyzed, and they should play more active roles in mathematics class. Second, they should try to create the kinds of climate that encourages students to come up with ideas in an active manner. Third, earlier studies had focused on student-teacher interaction patterns, but this study found that the roles of the teachers depended on interaction with not only students but study aids and performance assessment materials, and that the interaction patterns hinged on their roles as well. Therefore more profound research efforts should be directed into this issue.

• School Mathematics
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• v.18 no.2
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• pp.257-275
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• 2016

The purpose of this study was to investigate the impact of multiple representations on students' understanding of fractions, decimals, and percent. The instructional approach integrating multiple representations was compared to traditional algorithmic instruction, a form of direct instruction. To examine and compare the impact of multiple representations instruction with traditional algorithmic instruction, pre and post tests consisting of five similar items were administered with 87 middle school students. Students' scores in these two tests and their problem solving processes were analyzed quantitatively and qualitatively. The quantitative results indicated that students taught by traditional algorithmic instruction showed higher scores on the post-test than students in the multiple representations group. Furthermore, findings suggest that instruction using multiple representations does not guarantee a positive impact on students' understanding of mathematical concepts. Qualitative results suggest that the limited use of multiple representations during a class may have hindered students from applying their use in novel problem situations. Therefore, when using multiple representations, teachers should employ more diverse examples and practice with multiple representations to help students to use them without error.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3643-3652
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• 2015

The aim of this study is to analyze the IAQ concentrations of school rooms. In this study we measured and characterized IAQ at 440 school rooms from May 2009 to November 2012. At some school rooms, the $PM_{10}$ concentrations exceeded the IAQ guidelines ($100{\mu}g/m^3$) of the Ministry of Education. $CO_2$ concentrations at high schools were 1.18 and 1.06 times higher than that of the elementary and middle schools, respectively. $CO_2$ concentrations of some school rooms were exceeded the IAQ guidelines (1,000 ppm). Moreover, TBC concentrations at elementary school rooms were 1.23 and 1.33 times higher than that of the middle schools and high schools, respectively. TBC and HCHO concentrations did not exceed the IAQ guidelines. The classroom/non-classroom ratio of $PM_{10}$ was 1.06, while that $CO_2$ was 1.04, HCHO was 0.62, and TBC was 1.16.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.111-122
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• 2021

Purpose: The purpose of this in vitro study was to investigate the flexural strength and translucency of three layers in 5Y-ZP and to assess the effect of additional firings on these properties. Materials and Methods: Sintered zirconia blocks were sectioned according to three layers : incisal, transition, and body. Disc-shaped specimens were fabricated from each layer. The diameter of specimens was 15.0 mm and each thickness of specimens for biaxial flexural strength test and translucency was 1.2 mm and 1.0 mm. The specimens were classified into subgroups according to the number of firing (0, 1, and 3 times; n = 10/subgroup) and the additional firings were performed under 900℃ using a furnace. Biaxial flexural strength and translucency was measured using universal testing machine and uv-vis spectrophotometer. X-ray diffraction (XRD) analysis was used for measurement of the phase identification. One-way ANOVA, Tukey HSD test were performed (α = 0.05). Results: There was no significant difference in flexural strength between the three layers (P > 0.05), while there was significant difference in translucency between different layers (P < 0.05). The flexural strength of incisal and transition layer was decreased by the single additional firing, and the three additional firings significantly decreased the flexural strength of three layers. The translucency of layer was decreased by additional firings except the body layer. The XRD patterns of all groups were similar. Conclusion: Three layers of 5Y-ZP were different only in translucency. Additional firings affected the flexural strength and translucency differently depending on the layers but crystalline phases were not changed.

• Journal of Korean Society of Spine Surgery
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• v.25 no.4
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• pp.180-184
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• 2018

Study Design: Case report Objectives: To document fistula formation between the disc and dura by an unrecognized dural tear after percutaneous endoscopic lumbar discectomy (PELD). Summary of Literature Review: The risk of durotomy is relatively low with PELD, but cases of unrecognized durotomies have been reported. An effective diagnostic tool for such situations has not yet been identified. Materials and Methods: A patient twice underwent transforaminal PELD under the diagnosis of a herniated lumbar disc at L4-5. She still complained of intractable pain and motor weakness around the left lower extremity at 6 months postoperatively. Magnetic resonance imaging showed no specific findings suggestive of violation of the nerve root. However, L5 and S1 nerve root injury was noted on electromyography. An exploratory operation was planned to characterize damage to the neural structures. Results: In the exploration, a dural tear was found at the previous operative site, along with a fistula between the disc and dura was also found at the dural tear site. The durotomy site was located on the ventrolateral side of the dura and measured approximately 5 mm. The durotomy site was repaired with Nylon 5-0 and adhesive sealants. The patient's preoperative symptoms diminished considerably. Conclusions: Fistula formation between the disc and dura can be caused by an unrecognized dural tear after PELD. Discography is a reliable diagnostic tool for fistulas formed by an unrecognized durotomy.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.2
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• pp.81-89
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• 2019

Purpose: This study aimed to investigate the correlation between the solubility and the amount of fluoride release when a resin surface coating agent is applied to RMGIC. Materials and Methods: To measure the fluoride release and solubility, Fuji II $LC^{(R)}$and $Filtek^{TM}$ Z350XT without a surface coating, Fuji II $LC^{(R)}$ with G coat $plus^{TM}$ and Fuji II $LC^{(R)}$ with $Permaseal^{(R)}$ were prepared. And the amount of fluoride release and solubility were measured. Results: There was no significant difference in the daily fluoride release between the surface coating agents. The cumulative fluoride release was significantly different between the groups using RMGIC at 56 days (P < 0.05). In the solubility measurement, RMGIC without surface coating was significantly different only on the 7th day compared to the other three groups (P < 0.05). Conclusion: Surface coating agents can prevent the degradation of properties by the initial solvent in RMGIC. Therefore, fluoride is preserved inside the restorative material and the effect of surface coating after the addition is reduced, so that the effect on fluoride release and storage is also reduced.

• Journal of Dairy Science and Biotechnology
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• v.36 no.4
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• pp.208-219
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• 2018

Emergence of drug resistant strains of Salmonella enterica threatens milk processing and related dairy industries, thereby increasing the need for development of new anti-bacterials. Developments of antibacterial drugs are largely aimed to target the bacterial envelope, but screening their efficacy on bacterial envelope is laborious. This study presents a potential biosensor for envelope-specific stress in which a gfp reporter gene fused to spy gene encoding a periplasmic chaperone protein Spy (spheroplast protein y) that can sense envelope stress signals transduced by two major two-component signal transduction systems BaeSR and CpxAR in Salmonella enterica serovars Enteritidis and S. Gallinarum. Using spy-gfp operon fusions in S. Enterititis and S. Gallinarum, we found that spy transcription in both serovars was greatly induced when Salmonella cells were forming the spheroplast and were treated with ethanol or a membrane-disrupting antibiotic polymyxin B. These envelope stress-specific inductions of spy transcription were abrogated in mutant Salmonella lacking either BaeR or CpxR. Results illustrate that induction of Spy expression can be efficiently triggered by two-component signal transduction systems sensing envelope stress conditions, and thereby suggest that monitoring the spy transcription by spy-gfp operon fusions would be helpful to determine if developing antimicrobials can damage envelopes of S. Enteritidis and S. Gallinarum.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.219-224
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• 2019

Purpose: The image registration of radiographic image and digital surface data is essential in the computer-guided implant guide system. The purpose of this study was to examine the effects of using micro-screw on the working time and convenience of operators in the process of image matching for guided implant surgery. Materials and methods: A mandibular dental model was prepared in partial edentulism for Kennedy class I classification. Two micro-screws were placed on the each side of retromolar area. Radiographic and scan images were taken using computed-tomography and digital scanning. The images were superimposed by 12 operators in software in two different conditions: using remaining teeth image alone and using teeth and micro-screws images. Working time, operator convenience and satisfaction were obtained, and analyzed using the Mann-Whitney U test (${\alpha}=.05$). Results: The working time was not statistically different between image registration conditions (P>.05); however, operator convenience and satisfaction were higher in the teeth and micro-screw assisted condition than in the teeth-alone assisted condition (P<.001). Conclusion: The use of micro-screw for the image registration has no effect in working time reduction, but improves operator convenience and satisfaction.

• Journal of Life Science
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• v.29 no.8
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• pp.888-894
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• 2019

Cartilage diseases, such as rheumatoid arthritis (RA) and osteoarthritis (OA), are associated with the loss of chondrocytes and degradation of articular cartilage. Recent studies revealed that inflammatory reactive oxygen species (ROS) and age-related oxidative stress can affect chondrocyte activity and cartilage homeostasis. We investigated changes in the levels of intracellular antioxidants during cellular senescence of primary chondrocytes from rat articular cartilages. Cellular senescence was induced by serial subculture (passages 0, 2, 4, and 8) of chondrocytes and measured using specific senescence-associated ${\beta}$-galactosidase ($SA-{\beta}-gal$) staining. ROS production increased significantly in the senescent chondrocytes. In addition, total glutathione (GSSG/GSH) and superoxide dismutase (SOD) levels and heme oxygenase-1 (HO-1) expression increased in senescent chondrocytes induced by serial subculture. Analysis of changes in intracellular antioxidant levels in articular cartilage from rats of different ages (5, 25, 40, and 72 wk) revealed that total glutathione levels were highest after 40 wk and slightly decreased after 72 wk as compared with those after 25 wk. SOD and HO-1 expression levels increased in accordance with age. Based on these results, we conclude that intracellular antioxidants may be associated with cartilage protection against excessive oxidative stress in the process of chondrocyte senescence and age-related cartilage degeneration in an animal model.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.139-146
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• 2019

This study aimed to analyze the association of midpalatal suture (MPS) maturation stages with skeletal maturation and age and to obtain references for establishing a treatment plan for rapid maxillary expansion (RME). Cone-Beam Computed Tomography (CBCT) images from 480 children (240 boys, 240 girls) aged 7 - 15 years were obtained. MPS maturation stages and cervical vertebral maturation indicator (CVMI) were evaluated, and the correlations between MPS maturation stages, CVMI, and age were determined using the Spearman's correlation test. The positive likelihood ratio (LHR) of CVMI for MPS maturation stages was calculated. MPS maturation stages and CVMI showed a strong correlation. Especially, CVMI 1 - 3 showed positive LHR greater than 10 for the diagnosis of stages A - C. MPS maturation stages and age were correlated strongly in girls and moderately in boys. Conventional RME produces the most favorable skeletal effect at CVMI 1 - 3 or those up to 12 years of age and fewer skeletal effects at CVMI 4 or at 13 years of age in girls and 13 - 15 years in boys. It is recommended to evaluate MPS maturation stages using CBCT before RME application at CVMI 5, 6 or at 14, 15 years of age in girls.