• The korean journal of orthodontics
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• v.20 no.1
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• pp.123-133
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• 1990

The work was undertaken to evaluate the calcification of the second and the third molars in skeletal Class II and III malocclusions. The differences in the calcification stages between skeletal Class II and III malocclusion were evaluated and statistically analysed from panoramic radiographs of 202 males and females ranging in age from 11 to 15 years old. The results were as follows, 1. The calcification stages of the second and the third molars were not different between the skeletal Class II and III malocclusions in each age groups of both sexes. 2. The calcification stages of lower second and third molars of the skeletal Class III malocclusion are more advanced than those of the skeletal Class II malocclusion in male. 3. The clacification stages of upper second and third molars are more advanced than those of lower second and third molars in skeletal Class II malocclusion. 4. The calcification stages of lower second and third molars are more advanced than those of upper second and third molars in skeletal Class III malocclusion.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.1
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• pp.167-174
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• 2013

The main goal in the present paper is to obtain a solution of Einstein's unified field equations for the third class in $X_4$.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.1
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• pp.149-160
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• 1992

The purpose of this study was to localize the inferior alveolar canals in relation to the root apices of the mandibular third molars, according to their positions and degrees of impaction using vertical tube shift technique. One hundred three mandibular third molars, from 95 persons consisted of 57 males and 38 females, were clinically and radiographically investigated. The mandibular third molars had no pericoronitis and periapical lesions, and showed an evidence of complete root formation. The obtained results were as follows: 1. In localiztion of the inferior alveolar canals in relation to the root apices of the mandibular third molars, the inferior alveolar canal was located at the buccal side of the root apices of mandibular third molar in 77.7%, below the root apices in 16.5%, and the lingual side of root apices in 5.8%. 2. The positions of the mandibular third molars according to the Winter's Classification were as follows; 36.9% in Class Ⅰ, 21.3% in Class Ⅱ, 14.7% in Class Ⅲ, 4.8% in Class Ⅳ, 1.9% in Class Ⅴ, 17.5% in Class Ⅵ, 2.9% in Class Ⅶ. In localization of the inferior alveolar canals in relation to the root apices of the mandibular third molars according to the Winter's Classification, 92.1 % of Class Ⅰ, 86.4% of Class Ⅱ, 80.0% of Class Ⅲ, and 100.0% of Class Ⅳ and Ⅴ were located at the buccal side. In Class Ⅵ, however, 33.3% was located at the buccal side, 44.5% below the root apices, and 22.2% at the lingual side. 3. The degree of impaction was revealed to be 53.4% in Degree Ⅰ, 36.9% in Degree Ⅱ, and 9.7% in Degree Ⅲ. In localization of the inferior alveolar canals in relation to the root apices of mandibular third molars according to degree of impaction, 98.2% of Degree Ⅰ was located at the buccal side. In Degree Ⅱ, 60.5% was located at the bucal side, 31.6% below the root apices, and 7.9% at the lingual side. In Degree Ⅲ, 30.0% was located at the buccal side, 40.0% below the root apices, and 30.0% at the lingual side.

• The korean journal of orthodontics
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• v.9 no.1
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• pp.117-123
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• 1979

The aspects examined in the present study concerning the location and position of the lower third molar and the interrelationships of this molar, the gonial angle, and the second lower molar in subjects aged 8-24 are based on measurements made from 472 orthopantomograms. The following conclusion were drawn on the basis of the present study. 1. The gonial angle decreased with age, but slight enlarging occurred in the age group 20-21. 2. The angulation of the third molar in relation to the second molar did not correlate with the size of the gonial angle but decreased with developmental stage. 3. The mesial angle between the longitudinal axis of the second molar and the mandibular base line correlated significantly with the gonial angle. The above angle were smaller in Class II, Divison 2 and larger in Class III than in Class I and Class II, Division 1. 4. The rate of presence of lower third molar was 74.4%.

• Journal of Korean Elementary Science Education
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• v.38 no.3
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• pp.360-374
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• 2019

The purpose of this study is to investigate the self-perceptions of the elementary school students' on the affective, behavioral and cognitive domains in science class. To see if there are differences in students' perceptions according to grade levels, a self-perception questionnaire was applied to third and fifth grade students in Seoul, Korea. The major results of the study are as follows. First, the perception level of the affective domain was higher than that of the cognitive domain in third grade students. There was no significant difference in the self-perception level of the fifth grade students. Both third and fifth grade students perceived the greatest improvement in the cognitive domain through one year of science teaching. Second, in the life science class, the same tendency was also observed. The students in the third and fifth grade reported that cognitive domains were the most improved through the one-year life science class. Third, when the students' perceptions were compared by grades, the third grade students showed higher self-perception scores than fifth grade students. As the grade increased, the perception scores of the students' lowered. Based on these findings, implications for science education research and teaching and learning at school are discussed.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.235-242
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• 2008

The purpose of this study was to investigate the relationship of the skeletal maturity of hand-wrist and the development of mandibular third molar in subjects with class I and class III malocclusion. The subjects used in this study were 304 children(149 boys, 155 girls) with class I malocclusions and 308 children( 153 boys, 155 girls) with class III malocclusions, ranged from 8 to 15 years of age. Hand-wrist radiographs and panoramic radiographs were used to evaluate the stage of skeletal maturity and teeth development. Fishman's method for the skeletal maturity stages of the hand-wrist and new six-developmental-stage method for the calcification stages of mandibular third molars were analyzed. The results were as follows : 1. In subjects with class I and class III malocclusion, skeletal maturity of the hand-wrist occured earlier in females than in males(p<0.05), while the calcification stages of mandibular third molars were no significant gender differences. 2. There were no significant differences between the groups, when comparing the skeletal maturity stages of the hand-wrist and the calcification stages of mandibular third molars between subjects with the class I and the class III malocclusion. 3. The correlation coefficients between the calcification stages of mandibular third molars and the skeletal maturity stages of the hand-wrist in subjects with class I and class III malocclusion showed a high interrelationship(p<0.01). 4. The correlation coefficients between the calcification stages of mandibular third molars and chronological age in subjects with class I and class III malocclusion showed a high interrelationship (p<0.01). As a result, there were no significant differences between class I and class III malocclusion group for skeletal maturity of the hand-wrist and third molar development.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.695-707
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• 1994

This study investigates the effects of third molar on the occlusal plane in Angle's class El malocclusion with possibilities of posterior crowding and the interrelationships of occlusal plane inclinations to other skeletal patterns. Above investigations might showed that considerations should be given to third molars with possibilities of posterior crowding in establishing diagnosis and treatment plans for Angle's class III malocclusion patients. The following conclusions were obtained 1. In events of third molars causing possible posterior crowding, maxillary third molars showed more mesial inclinations than second molars, and compared to those with third molar missing cases, first molars were more mesially inclined and displaced more inferiorly from the palatal plane and OP-MP was increase , thus the occlusal plane was less steep. 2. In events of third molars causing possible posterior crowding, the anglulation between AB line and mandibular plane was decreased and ANB showed negative values. Thus chin points were more protruded, ramus were more anteriorly displaced, and increase in lower facial height, genial angle, effective mandibular length and mandibular plane angle were observed. This in all caused more vertical opening and more severe skeletal disturbance. 3. OP-MP was increased as the maxillary first molars were more inferiorly displaced from the palatal plane. As this angle was increased mandibular planes were more inferiorly inclined and LFH, genial angle, effective mandibular length were more increased and mandibular ramus was more anteriorly placed. 4. As the maxillary first molars were more inferiorly placed from the palatal plane, more increased OP-MP/PP-MP ratio made the occlusal plane less steep. As OP-MP/PP-MP was increased, mandibular ramus was more anteriorly placed and made longer, and facial angle and effective mandibular length were increased.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.209-223
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• 2017

The purpose of this study is to compare and analyze science self-efficacy, science self-concept and scientific attitude according to the class size in the elementary school. For this purpose, three research questions were set as follows; First, are there any differences in science self-efficacy according to the class size? Second, are there any differences in science self-concept according to the class size? Third, are there any differences scientific attitude according to the class size? To solve this research questions, the subjects in this study were 809 5th and 6th grade students of eight elementary schools in Busan. 220 were sampled from small-size classes, 354 from mid-size classes and 235 from large-size classes. The results of this study through the process are as follows; First, there were significant differences in science self-efficacy according to the class size. Second, there were significant differences in science self-concept according to the class size. Third, according to the result, there was not a significant difference in scientific attitude according to the class size. The findings of the study suggest that it is necessary the class size should be adjusted to the appropriate level for improving student's science self-efficacy and science self-concept.

• Imaging Science in Dentistry
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• v.52 no.1
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• pp.19-25
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• 2022

Purpose: This study evaluated the distance from the posterior root apices to the maxillary sinus floor (MSF) and the frequency of roots touching or protruding through the MSF using cone-beam computed tomography (CBCT). Materials and Methods: This study included 100 subjects divided into different vertical and anteroposterior skeletal growth patterns. On CBCT images, the distance from the posterior root apices to MSF was measured and the frequency of roots touching or protruding through the MSF was evaluated using NNT software (version 5.3.0.0; ImageWorks, Elmsford, NY, USA). Results: No statistically significant differences were found in the distance from the posterior root apices to the MSF among vertical skeletal groups (P>0.05). The palatal roots of the first molar and the palatal, mesio-buccal and disto-buccal roots of the second molars had significantly less distance from MSF in skeletal class II than in class III (P<0.05). The high-angle group had the highest frequencies of roots touching or protruding into the maxillary sinus (49.8%); the lowest proportion of these roots was found in skeletal class III (28.3%) and the highest proportion in class II (50.3%). Males had shorter distances from the posterior root apices to the MSF and higher frequencies of roots protruding through or touching the MSF than females. Conclusion: Anteroposterior skeletal growth patterns and sex affected the distances from the maxillary posterior roots to the MSF. The frequency of roots protruding into or touching the sinus was affected by both vertical and anteroposterior skeletal groups and sex. These findings have implications for dental practice.

• Journal of Science Education
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• v.42 no.3
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• pp.352-370
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• 2018

The purpose of this study is to explore how Peer Instruction can continuously help improve third-grade students' participation and their ability to debate in Science classes. There were multiple-choice questions relating to the discussions and debating class and Peer Instruction of the entire third grade Science curriculum which had been applied for six months. Also, after looking into the class participation and the debating ability, there was a degree of increase. As a result, there were five areas in class participation which are class preparation, class activity, expressing oneself, class expansion, and class dedication; all have statistically significant effects on the six areas of the discussion skill: logic, analytical skill, listening skill, receptiveness, regularity, and initiative. As it shows, both of these areas show a significant statistical effect on the application of Peer Instruction and confirmed to have a positive influence on the change in the participation and the discussion skills.