• The korean journal of orthodontics
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• v.17 no.1
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• pp.119-134
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• 1987

This study was undertaken to find out oropharyngeal movement of the class III malocclusion patients during swallowing by using the cinefluoroscopic method. The experimental group was composed of fifteen male adults with class III malocclusion whose mean age was 24.4 yrs. The control group was composed of fifteen male adults with normal occlusion whose mean age was 24.8 yrs. The results were as follows: 1. The horizontal position of the tongue tip was more anterior in the class III malocclusion group than in the normal group through all stages. 2. The tongue level was lower in the class III malocclusion group than in the normal group during stage 1, stage 3, and stage 4. 3. The horizontal position of the hyoid bone was more anterior in the class III malocclusion group than in the normal group during stage 1 only. 4. The tip of the soft palate was lower in the class III malocclusion group than in the normal group during stage 1 only, and there was no significant difference in the velar movement between the class III malocclusion group and the normal group during swallowing. 5. There was a significant difference in the interincisal distance, but no significant difference in the intermolar distance between the class III malocclusion group and the normal group through all stages. 6. Among 4 stages of each group, there was a significant difference in the movements of the dorsum of the tongue, the hyoid bone, and the soft palates And there was a significant difference in the movement .of the tongue tip of the normal group, but no significant difference in the movement of the tongue tip of the class III malocclusion group.

• The Korean Journal of Elementary Counseling
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• v.11 no.1
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• pp.35-49
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• 2012

The purpose of this study was to examine the influence of self-encouragement activities on elementary students' adaptation to school life. Two classes were sampled among 5th grade at Y elementary school in Gwangju Metropolitan city. One class was assigned to experimental group and the other class was assigned to control group. Experimental group had 8 sessions of self-encouragement activities. To prove the effect of self-encouragement activities, data were collected through pre and post test on adaptation to school life of the students, and were analysed via ANCOVA. The results of this study are following; First, the experimental group had improved significantly in school adaptability than the control group. Second, there was showed significant improvement in teacher-student relationship adaptation, peer relationship adaptation, classwork adaptation, school rule adaptation in the experimental group.

• Journal of Korean Home Economics Education Association
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• v.14 no.3
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• pp.1-9
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• 2002

The objectives of this study were to measure the effect of Practical Reasoning Instruction in Home Economics : specifically. its effect on developing of critical thinking as well as to evaluate the degree of the critical thinking process. with reference to its sub-factors and the level. The research subjects were consisted of the experimental group of 119 freshman class female students from the “A” High School and the comparative group of 110 freshman class female student from the “C” High School in the city of Chung-Ju. This research was conducted under the pre-post test control group design. administering the Pre-Post testing to both the experimental and the comparative groups. The experimental group was subjected to Practical Reasoning Instruction in Home Economics : whereas the comparative group was taught under the lecture-Instruction in Home Economics The research findings are as follows: 1. Those who studied Home Economics under the Practical reasoning method scored higher on the critical thinking Process than the comparative group students who were taught Home Economics in the lecture-style approach. 2. The experimental group of students. who studied Home Economics under the Practical reasoning method. scored higher than the comparative group in their ability to perceive assumption and to render Judgment among the five sub-factors of their critical thinking processes.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.99-104
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• 2020

In this paper, efficiency and loss characteristics of GaN FET were reported by applying it into the QR flyback converter. In particular, for the comparison of efficiency characteristics, QR flyback converter experimental circuits with Si FET and with GaN FET were separately produced in 12W class. As a result of the experiment, the experimental circuit of the QR flyback converter using GaN FET reached a high efficiency of 90% or more when the load power was 2W or more, and the maximum efficiency was observed to be about 92%, and the maximum loss power was about 1.1W. Meanwhile, the efficiency of the experimental circuit with Si FET increased as the input voltage increased, and the maximum efficiency was observed to be about 82% when the load power was 9W or higher, and the maximum loss power was about 2.8W. From the results, it is estimated that that in the case of the experimental circuit applying the GaN FET switch, the power conversion efficiency was improved as the switching loss and conduction loss due to on-resistance were reduced, and the internal loss due to the synchronous rectifier was minimized. Consequently, it is concluded that the GaN FET is suitable for under 20W class power supply unit as a high efficiency power switch.

• Journal of The Korean Association For Science Education
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• v.29 no.4
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• pp.388-399
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• 2009

This study was designed to investigate whether applying mind mapping in a biology class had an effect on students' creativity. Participants of this study were 165 1st grade middle school students. The pretest-post test control group design was employed. A control group was instructed with a traditional method and an exerimental group was instructed using the mind-map applied method. The units "Digestion and Circulation" and "Respiration and Excretion" were selected for this study, and each group was treated for 24 class hours. To measure student creativity, the TTCT test was used. For assessing students' level of logical thinking, the compact version of GALT was used. Test results were analyzed by ANCOVA and correlation analysis by SPSS 12.0. The creativity of students in experimental group was significantly improved than the control group (p< .01). Fluency, flexibility, and originality of students in experimental group were improved (p< .01). Students did not show any differences on creativity according to their academic achievement level or gender (p> .05) in the experimental group. Students did not show any differences on creativity according to their logical thinking level (p> .05), either. However, the students of logical thinking level in the experimental group improved their flexibility (p< .05). There was no correlation between students' creativity and their achievement (p> .05), but the creativity shows a lower correlation to performance evaluation (p< .05).

• 대한공업교육학회지
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• v.45 no.1
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• pp.20-41
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• 2020

The purpose of this study is to explore ways to improve teaching and learning in specialized high schools by investigating the relationship between creativity and class satisfaction in classes using the NFTM-TRIZ model for specialized high school students. In order to achieve the purpose of the research, first, the differences between the applied effects, experiments, and control groups were analyzed when the NFTM-TRIZ model was applied. Second, when the NFTM-TRIZ model was applied, it was analyzed whether there was a significant difference in creativity and class satisfaction by group size. The conclusions of this study are as follows. First, as a result of comparing the preand post-tests of the experimental group and the control group applying the NFTM-TRIZ model through the t-test, the experimental group showed significant differences in creative spontaneity, identity, attachment, curiosity and class satisfaction. Second, in experimental groups with the NFTM-TRIZ model, the size of groups of 4 and 6, rather than the size of groups of 2, had positive effects on class satisfaction. Therefore, the NFTM-TRIZ model based on collaborative learning was effective as a teaching and learning method that promoted creativity and satisfaction of students in specialized high schools.

• The Mathematical Education
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• v.47 no.1
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• pp.27-47
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• 2008

In this paper, we study the effect of writing activity as mathematical communication on the students's mathematics achievement, learning attitude, and mathematical tendency. For this purpose, we construct a experimental class and then analyze the students' change in those aspects after applying three-divided-note writing activity and colleague feedback on their works those students are in the experimental class. As a result of the experiment, we find that three-divided-note writing activity and colleague feedback made some significant changes on the students achievement in mathematics, learning attitude, but does not affect on mathematical tendency. We also offer some suggestions for further research. Firstly, the mathematical communication ability must be stressed in mathematics education. For this purpose, we need to develop the teaching and the evaluation method to use not only writing but also reading, speaking, and listening skills so that many teachers can apply this method easily to their classes. Second, we need to fix some realistic problems such as fair evaluation , the numbers of students per class, the numbers of lesson, and too much extra-work, and so on. Thirdly, we suggest to explore some methods for extending three- divided-note writing activity to evaluate mathematical essay and to study educational effects of colleague feedback on mathematics performance assessment.

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.736-743
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• 2010

This study examined the ecological attributes of classified forest community by cluster analysis in the mixed forest of Mt. Seokbyung Experimental Forest of Gangwon-Do. The vegetation data were collected in randomly established 51 sample plots (2.04 ha) and analysis adopted the cluster analysis, importance value index, and Shannon's diversity index. Main results were as follows; 1) the study area was classified into 4 clusters (A, B, C and D). 2) The cluster A was dominated by Pinus densiflora with an importance value of 71.6%. The most dominant species in the cluster B and cluster C were Larix leptolepis (57.1%) and Quercus mongolica (40.2%), respectively. Finally, The cluster D was dominated by P. densiflora (30.6%) and Q. mongolica (31.0%) with the mixed forest. 3) In the P. densiflora community (cluster A), distribution of DBH class showed a reverse J-shaped curve. In the L. leptolepis community (cluster B), individuals of dominant species had the bell-shaped distribution. Oak species indicated uniform distribution of DBH class (under 25 cm) in the mixed P. densiflora - Q. mongolica community (cluster D). 4) The species diversity index of the communities in descending order were: Pinus densiflora - Q. mongolica community > Larix leptolepis community > Pinus densiflora community > Quercus mongolica community.

• English Language & Literature Teaching
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• v.12 no.4
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• pp.211-234
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• 2006

The purpose of the present study was to investigate how two types of cooperative groupworks will affect learners' academic self-efficacy and English achievement in the first graders of Middle school. Experimental class A was done by similar-level groupwork, experimental class B by differential-level groupwork, and controlled class C by whole classwork. In order to accomplish the goals of the study, questionnaires on learners' academic self-efficacy were examined before and after the experiment. Also English achievement tests were done during the experiment. The analytic results of the questionnaires and English achievement tests were like the following conclusions: First, two types of cooperative groupworks were more effective on improving learners' academic self-efficacy than the whole classwork. Second, two types of cooperative groupworks were more effective on improving two levels' (higher and medium) academic self-efficacy. Third, among three types of classworks, differential-level groupwork was the most effective on improving learners' English achievement. Fourth, in case of medium-level learners, differential-level groupwork was more effective on improving their English achievement than similar-level groupwork.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.90-98
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• 1998

Forging of internal involute gears with alloy steel has been analyzed by means of upper bound method. Kinematically admissible velocity fields for forging of internal gear were proposed. It was assumed that the shape of free flow surface during forging operation is a straight line perpendicular to the plane of symmetry. Using the suggested velocity fields, forging loads and relative pressures were calculated by numerical method. Consequently forging die should be successfully designed without fracture or failure during forging operation. Experiments were carried out with the designed die and SCM415 alloy steel as billet material. The calculated loads were compared with experimental one and they are in good agreement with experimental inspections. As a result, the calculated solutions would be useful to predict the loads and the designed die is suitable for forging of internal involute spur gear with alloy steel. The forged gear is measured to be KS 4 class and its class should be improved by subsequent working such as shaving after forging operation.