• The korean journal of orthodontics
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• v.51 no.6
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• pp.407-418
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• 2021

Objective: To investigate differences in the heritability of skeletodental characteristics between twin pairs with skeletal Class I and Class II malocclusions. Methods: Forty Korean adult twin pairs were divided into Class I (C-I) group (0° ≤ angle between point A, nasion, and point B [ANB]) ≤ 4°; mean age, 40.7 years) and Class II (C-II) group (ANB > 4°; mean age, 43.0 years). Each group comprised 14 monozygotic and 6 dizygotic twin pairs. Thirty-three cephalometric variables were measured using lateral cephalograms and were categorized as the anteroposterior, vertical, dental, mandible, and cranial base characteristics. The ACE model was used to calculate heritability (A > 0.7, high heritability). Thereafter, principal component analysis (PCA) was performed. Results: Twin pairs in C-I group exhibited high heritability values in the facial anteroposterior characteristics, inclination of the maxillary and mandibular incisors, mandibular body length, and cranial base angles. Twin pairs in C-II group showed high heritability values in vertical facial height, ramus height, effective mandibular length, and cranial base length. PCA extracted eight components with 88.3% in the C-I group and seven components with 91.0% cumulative explanation in the C-II group. Conclusions: Differences in the heritability of skeletodental characteristics between twin pairs with skeletal Class I and II malocclusions might provide valuable information for growth prediction and treatment planning.

• Korean Journal of Mathematics
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• v.9 no.2
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• pp.157-164
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• 2001

We construct an operad which is called the mapping class group operad. Its structure map is induced by the attachings of surfaces. The similar operad was constructed by Tillmann in order prove that ${\Gamma}^+_{\infty}$ is an infinite loop space. Our operad is rather simpler and easier to deal with.

• Bulletin of the Korean Mathematical Society
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• v.53 no.2
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• pp.601-614
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• 2016

Let $N_{g,s}$ denote the nonorientable surface of genus g with s boundary components. Recently Paris and Szepietowski [12] obtained an explicit finite presentation for the mapping class group $\mathcal{M}(N_{g,s})$ of the surface $N_{g,s}$, where $s{\in}\{0,1\}$ and g + s > 3. Following this work, we obtain a finite presentation for the subgroup $\mathcal{T}(N_{g,s})$ of $\mathcal{M}(N_{g,s})$ generated by Dehn twists.

• The korean journal of orthodontics
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• v.39 no.3
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• pp.136-145
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• 2009

Objective: CBCT has become popular for orthodontic diagnosis and treatment planning in recent times. The 3D pharyngeal airway space needs to be analysed using a 3D diagnostic tool. The aim of this study was to analyse the pharyngeal airway of different craniofacial morphology using CBCT. Methods: The sample compromised 102 subjects divided into 3 groups (Class I, II, III) and 6 subgroups according to normal or vertical craniofacial patterns. All samples had CBCT (VCT, Vatech, Seoul, Korea) taken for orthodontic treatment. The pharyngeal airway was assessed according to the reference planes: aa plane (the most anterior point on the anterior arch of atlas), $CV_2$ plane, and $CV_3$ plane (most infero-anterior point on the body of the second & third cervical vertebra). The intergroup comparison was performed with one-way ANOVA and duncan test as a second step. Results: The results showed the pharyngeal airway and anteroposterior width of group 2 (Class II) in aa plane, $CV_2$ plane, $CV_3$ plane were significant narrower than in group 3 (Class III). There was no significant difference between vertical and normal craniofacial patterns except for the anteroposterior pharyngeal width of Group 1 (Class I) in aa plane. Conclusions: Subjects with Class II patterns have a significantly narrower pharyngeal airway than those with Class III. However there was no difference in pharyngeal airway between vertical and normal craniofacial morphology.

• Journal of Information Processing Systems
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• v.15 no.2
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• pp.320-330
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• 2019

This study analyzed changes in sociality and democratic-citizenship among elementary school students in the information class and the science class at the Science Education Institute for the Gifted, who were divided into an experimental group and a control group. The experimental group engaged in the Learning Together (LT) cooperative form of learning for which the remix function of Scratch, an educational programming language, was applied, while the control group was given general instructor-led lessons. Members in the experimental group were able to modify processes during projects through the usage of the remix function, thereby actively participating in the projects and eventually generating team-based results. The post-class t-tests showed a greater degree of improvements in sociality and democratic citizenship for the experimental group that was offered the remix-function-based cooperative learning than the control group. Statistically significant differences were present between two groups particularly in "cooperative spirit" sub-domain of sociality and the "community" and "responsibility" sub-domains of democratic citizenship.

• Journal of Families and Better Life
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• v.19 no.6
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• pp.113-128
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• 2001

middle and upper class families, and examine obstacles to their introduction in Korea. Since a few large-scale facilities for the elderly with dementia have been provided for only low-income families free of charge, the necessity of group homes for middle and upper class families willing to pay for such services has become an issue recently in order to lessen the burden on families, as well as to promote the well-being of the dementia victims themselves. The survey was conducted by questionnaires collected from 577 respondents from middle and upper class families. The results of the survey were as follows: The merits of the group homes were 1)decreasing loneliness of the elderly, 2)providing active and stimulating environments allowing for participation everyday life activities, and 3)lessening the emotional and physical burden on the caring families. Potential obstacles to its introduction in Korea were 1)the difficulty of finding sites to build the group home because of the negative perception of people with disabilities and a NIMBY(Not In My Back Yard) reaction to the construction of it and 2)the economic burden on the caring family. Surprisingly, the guilt factor associated with sending the parents into group homes was not considered as a big obstacle. Referring to results of this study, it is asserted that group homes for the elderly with dementia would be embraced throughout the country if Koreans could have the chance to understand what group homes are.

• Communications of the Korean Mathematical Society
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• v.11 no.2
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• pp.481-493
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• 1996

We consider a retrial queue with two classes of customers where arrivals of class 1(resp. class 2) customers are MMPP and Poisson process, respectively. In the case taht arriving customers are blocked due to the channel being busy, the class 1 customers are queued in priority group and are served as soon as the channel is free, whereas the class 2 customers enter the retrial group in order to try service again after a random amount of time. We consider the following retrial rate control policy, which reduces their retrial rate as more customers join the retrial group; their retrial times are inversely proportional to the number of customers in the retrial group. We find the joint generating function of the numbers of custormers in the two groups by the supplementary variable method.

• The korean journal of orthodontics
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• v.48 no.6
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• pp.349-356
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• 2018

Objective: This study was performed to investigate the alveolar bone of lower incisors in skeletal Class III adults of different vertical facial patterns and to compare it with that of Class I adults using cone-beam computed tomography (CBCT) images. Methods: CBCT images of 90 skeletal Class III and 29 Class I patients were evaluated. Class III subjects were divided by mandibular plane angle: high (SN-MP > $38.0^{\circ}$), normal ($30.0^{\circ}$ < SN-MP < $37.0^{\circ}$), and low (SN-MP < $28.0^{\circ}$) groups. Buccolingual alveolar bone thickness was measured using CBCT images of mandibular incisors at alveolar crest and 3, 6, and 9 mm apical levels. Linear mixed model, Bonferroni post-hoc test, and Pearson correlation analysis were used for statistical significance. Results: Buccolingual alveolar bone in Class III high, normal and low angle subjects was not significantly different at alveolar crest and 3 mm apical level while lingual bone was thicker at 6 and 9 mm apical levels than on buccal side. Class III high angle group had thinner alveolar bone at all levels except at buccal alveolar crest and 9 mm apical level on lingual side compared to the Class I group. Class III high angle group showed thinner alveolar bone than the Class III normal or low angle groups in most regions. Mandibular plane angle showed negative correlations with mandibular anterior alveolar bone thickness. Conclusions: Skeletal Class III subjects with high mandibular plane angles showed thinner mandibular alveolar bone in most areas compared to normal or low angle subjects. Mandibular plane angle was negatively correlated with buccolingual alveolar bone thickness.

• The korean journal of orthodontics
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• v.43 no.3
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• pp.134-140
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• 2013

Objective: To evaluate lower incisor position and bony support between patients with Class II average- and high-angle malocclusions and compare with the patients presenting Class I malocclusions. Methods: CBCT records of 79 patients were divided into 2 groups according to sagittal jaw relationships: Class I and II. Each group was further divided into average- and high-angle subgroups. Six angular and 6 linear measurements were performed. Independent samples t-test, Kruskal-Wallis, and Dunn post-hoc tests were performed for statistical comparisons. Results: Labial alveolar bone thickness was significantly higher in Class I group compared to Class II group (p = 0.003). Lingual alveolar bone angle (p = 0.004), lower incisor protrusion (p = 0.007) and proclination (p = 0.046) were greatest in Class II average-angle patients. Spongious bone was thinner (p = 0.016) and root apex was closer to the labial cortex in high-angle subgroups when compared to the Class II average-angle subgroup (p = 0.004). Conclusions: Mandibular anterior bony support and lower incisor position were different between average- and high-angle Class II patients. Clinicians should be aware that the range of lower incisor movement in high-angle Class II patients is limited compared to average- angle Class II patients.

• Journal of Korean Elementary Science Education
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• v.33 no.1
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• pp.69-81
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• 2014

This study was to find out the effects of out-of-class environmental experience learning on elementary students' environmental literacy. For this study, we developed and applied environmental education program utilizing out-of-class facilities and ecological park for the 5th-grade students. The subjects of this study were the 5th grade students of an elementary school located in Si-hung city. The study was carried out for two groups, an experiment group of 29 students and control group of 29 students. The education program using out-of-class environmental experience learning was provided to the experiment group while lecture-oriented education program was provided to the control group. The questionnaire used in this study to assess the environmental literacy of the study objects consists of 41 questions under 4 domains (knowledge, emotion, skill, behavior). After observing and analyzing the effects of out-of-class environmental experience learning on students' environmental literacy, we found that the program using the out-of-class environmental experience learning posed greater impacts than lecture-oriented program. By domains, environmental literacy in 3 domains illustrated positive improvement. In particular, skill domain illustrated much more improvement in environmental literacy. But, domain of behavior didn't illustrated improvement in environmental literacy. The result of this study signified that the out-of-class environmental experience learning has positive and effective impact on the environmental literacy. And out-of-class environmental experience learning is more suitable to improve the skill domain of the environmental literacy than lecture-oriented learning. But, it is couldn't improve the domain of behavior. Therefore, in order to improve behavior domain, the program must apply with effective evaluation and home training.