• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.83-88
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• 2007

The reliability characteristics of class-E RF power amplifier are studied, based on the degradation of MOSFET electrical characteristics. The class-E power amplifier operates as a switch mode operation to achieve high efficiency. This operation leads to high voltage stress when MOSFET switch is turned-off. The increase in threshold voltage and decrease in nobility caused by high voltage stress leads to a drop in the drain current. In the class-E power amplifier the effects caused by the degradation of MOSFET drain current is a drop of the power efficiency and output power. But the small inductor in the class-E load network allows the reliability to be improved. After $10^{7}\;sec$. the drain current decreases 46.3% and the PAE(Power Added Efficiency) decreases from 58% to 36% when the load inductor is 1mH. But when the load inductor is 1nH the drain current decreases 8.89% and the PAE decreases from 59% to 55%.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.323-331
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• 1994

1,050 patients who visited orthodontic dental department from 1983 to 1994, were surveyed on the yearly tendency of orthodontic patient distribution and state by means of Angle's classification. The results were as follows: 1. There was increased visiting rate of patient per year and higher visiting rate in female than in male. 2. 8-15 age group was 61.4% in total visiting patients and over 20 age group was 18.5%, under 7 age group was 8.1% 3. Class I malocclusion was 42.2%, class II div 1 was 22.5%, class II-2 was 3.9%, class III was 29.1% and cleft lip & palate was 2.0% in total visiting patient. 4. As showed the living distribution, Namgu and Susunggu's patients were 43.7% of the total patients. 5. There was increased tendency for the number of the patient to be recieved orthognathic surgery.

• The korean journal of orthodontics
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• v.20 no.1
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• pp.111-122
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• 1990

To investigate the relationship of skeletal maturity among the normal occlusion group and each malocclusion groups, the author used hand and wrist X-ray of 133 Korean 13 year old boys (normal occlusion 30, Class I malocclusion 35, Class II malocclusion 35 and Class III malocclusion 33) and assessed their skeletal maturity. In this study, fourteen skeletal maturity stages were selected from; Radius, Hamate, Pisiform, Ulnar sesamoid of the metacarpophalangeal joint of the first thumb, proximal phalanges of the first, second and third finger, middle and distal phalanx of the third finger. The difference of skeletal maturity of each malocclusion groups in relative to normal occlusion group and that of each malocclusion groups were analyzed. The findings of this study can be summerized as follows: 1. Average skeletal maturity stage of each groups were MP3cap stage in normal occlusion group, H-2 stage in Class I malocclusion group, midstage between S and H-2 stage in Class II malocclusion group, MP3cap stage in Class III malocclusion group. 2. There was no significant difference in skeletal maturity of Class I malocclusion and Class III malocclusion groups in relative to normal occlusion group. 3. There was significant retardation of skeletal maturity in Class II malocclusion group in relative to normal occlusion group. 4. There was no significant difference in skeletal maturity between Class I and Class II malocclusion groups. 5. There was no significant difference in skeletal maturity between Class I and Class III malocclusion groups. 6. There was significant retardation of skeletal maturity in Class II malocclusion group in relative to Class III malocclusion group.

• The korean journal of orthodontics
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• v.17 no.1
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• pp.63-72
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• 1987

This is to investigate the difference between craniofacial correlation of Angle's class III malocclusion and that of normal occlusion. For this investigation, 28 adult males and famales, who have class III malocclusion, and 35 adult males and 46 adult famals., who have normal occlusion were selected to measure actual dimension of cranial base and to investigate ratio of various parts of maxillofacial skeleton against cranial base. Class III malocclusion were, also , classified based on SNA and SNB angle in normal range. Results were as follows. 1. In class III malocclusion, actual dimension of cranial base were appeared to be less than normal occlusion in both sex. 2. In class III malocclusion, values were less than normal occlusion in BN/ptm-A in both sex, but had no significance between two. 3. In class III malocclusion, ramal inclination, mandible inclination, BN/Go-Pog, lower genial angle were appeared to be greater. Thus, characteristic mandibular protrusive appearance of class III malocclusion was due to relative ratio and morphologic characteristic of mandibular body dimension against cranial base. 4. In class III malocclusion, upper incisors were labially tilted and lower incisors were lingually tilted compared to normal occlusion. 5. In typing of class III malocclusion, the most common type was found to be one which maxillas were in normal range, while mandibles were in protrusive tendency.

• 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.

• Journal of the Korean Society of Earth Science Education
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• v.9 no.1
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• pp.54-64
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• 2016

The purpose of this study was to see the influences of science class applying learning cycle emphasized exploration on science learning motivation and scientific attitude of elementary students. The results drawn from this analysis were as below. Firstly, positive relationship was found between science learning motivation and science class applying learning cycle emphasized exploration among the research group. This shows that science learning motivation was improved by science class applying learning cycle emphasized exploration. It indicates that science class applying learning cycle emphasized exploration is effective in improving science learning motivations. Secondly, positive relationship was found between scientific attitude and science class applying learning cycle emphasized exploration among the research group and this means that science class applying learning cycle that emphasizes exploration stimulates intellectual curiosity of elementary school students and improves their scientific attitude. Thirdly, students thought that science class applying learning cycle emphasized exploration was very effective to improve their satisfaction, interest, participation in their science classes. Above results show that science class applying learning cycle emphasized exploration is highly effective for elementary students. Thus, it is needed to utilize science class applying learning cycle emphasized exploration to current science class as it can promote wider scientific activities among elementary school students.

• Journal of Information Technology Applications and Management
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• v.29 no.1
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• pp.29-45
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• 2022

The Fourth Industrial Revolution era requires people to have the ability of integrated thinking, critics, sensitivity, and creativity in an integrated manner. Therefore, teaching methods are expected to become more suitable for the trend. In this belief, current teacher-leading education method should move to students' self motivating one and consist of programs in which students voluntarily involve. In this reason, this study suggests FPBL educational method model that is combines project-based learning with flipped learning by analysing preceding research and digital painting tool class was designed by applying it. As a result of applying the designed class model to the class, all of the class satisfaction, effectiveness, and interaction were evaluated positively. Problems such as limitations of project classes due to non-face-to-face classes, large amount of learning before class, and reduced concentration during class were found. Therefore, when the FPBL class model is conducted non-face-to-face, it will be necessary to further strengthen the role of the instructor, provide lecture videos summarizing the core contents, and improve concentration by providing active participation and fun using various digital tools. The result of the study looks significant by confirming the possibility of applying FPBL model not only in design education but also other educational settings.

• Journal of Sericultural and Entomological Science
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• no.11
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• pp.81-86
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• 1970

This report was prepared to compare and analyze the testing method and classification of winding test in Korea to that in Japan, and the obtained results, which had been carried out, in Korea, from Sep. to Nov. in 1968 and in Japan through June in 1968, was as followings. 1. In Korean raw silk, (21 D.) the average number of breaks on winding test showed 5.91 by Korean Method but showed 8.6 by Japanese method and the latter increased to 2.7. On the other hand in Japanese raw silk, it showed 3.6 by Korean method but 4.7 by Japanese method and the latter increased to 1.1. (See Table 2,3) 2. It was seemed the tendency that the lot distribution of breaks number in Korean silk was mostly concentrated to the breaks No. 3,4 and 5(48％) by Korean method but in case of Japanese method to the breaks number 5,6 and 7(36％), and the tendency that the concentration depended mostly on the increased number of breaks. In Japanese raw silk, it was seemed the tendency that the lot distribution of breaks number was mostly concentrated to the breaks number 1. 2, and 3 (55％) by Korean Method but in case of Japanese Method to the breaks number, 2,3 and 4(50％) and the tendency that the concentration was as similar as the above. (See Table 2,3) 3. It was found the tendency that the distribution of breaks number during the open winding test was mostly concentrate red to the average number of breaks not only in Korea but in Japan. The rate 0: non-breaks, however, showed 43％ of Japan, to 7％ of Korea. (See Table 4) 4. Applying Table 1,2 to the Classification of Korea and Japan, the class distribution by Korean table showed 68％ of class 1(6), 22％ of cl ass 2(10) and 9％ of class 3(15) in Korean silk, while that by Japanese table showed 13％ of class 1(4), 56％ of class 2(10) and 29％ of class 3(18). And then the testing result to be class 1 or 2 by Korean table was. degraded from class 1 to class 2 of 55％ and from class 2 to class 3 of 20％ down. In Japanese silk, however, the class distribution by Korean table showed 85％ of class 1 (4), 10％ of class 2(10) and 5％ of class 3(18) but that by Japanese table showed 60％ of class 1(4), 33％ of class 2(10) and 7％ of class 3(18). And then there was little difference in the rate of class distribution. 5. Through the above investigation, it was seemed that Japanese classification table was only prepared for the r∼w silk of Japan, considering that the width of class 1(4) in winding table was greatly tighter than that of Korea. Because it was generally evaluated that Korean silk in quality especially in the winding test was better (next to Japan) than any other countries. 6. We could venture to estimate that, applying to Japanese method, the testing result of break number in Korean silk would show from about 6 by Korean method to 9. And then it would be found degrading hi the testing result of winding test increased gradually.

• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.1008-1013
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• 2014

The use of antimicrobial agents for additives or therapeutics is strongly associated with a prevalence of antimicrobial resistance in commensal Enterobacteriaceae. We aimed to characterize integrons in Enterobacteriaceae isolates obtained from chicken cecums in Korea. Moreover, the correlation between integron gene cassettes and antimicrobial resistance was also investigated. A total of 90 isolates the belonged to Enterobacteriaceae were recovered from chickens grown at Gyeongsang and Chungcheong provinces in Korea. Antimicrobial susceptibility tests were performed by the disk diffusion method. PCR and DNA sequencing were also performed to characterize the gene cassette arrays of the integrons. Of the 90 Enterobacteriaceae isolates tested, 39 (43.3%) and 10 (11.1%) isolates carried class 1 and 2 integrons, respectively. Whereas the class 2 integron did not contain gene cassettes, the class 1 integrons carried seven different gene cassette arrays. The class 1 integrons harbored genes encoding resistant determinants to aminoglycosides (aadA1, aadA2, and aadA5), trimethoprim (dfrA1, dfrA12, dfrA17, and dfrA32), lincosamides (linF), and erythromycin (ereA). Moreover, the presence of a class 1 integron was significantly related to a high resistance rate of antimicrobial agents, such as spectinomycin and trimethoprim. We confirmed that diverse class 1 integrons were widely distributed in Enterobacteriaceae isolates from chickens and directly contributed to the resistance to diverse antimicrobial agents in Korea.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.587-603
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• 1998

Being in Learning-accomplishing rate on mutual cooperation studies of small group by different class, we can find that the sujective class of high group is much more efficient than the compared class of high group and that the subjective class of low group is more efficient than the compared class of low group as times goes. Moreover, in analysis of all directions on mathematical attitude, high group appears to be a great efficient in all areas such as confidence, flexibility, reaction, value, etc. and low group seems to have a little effect, by comparing the subjective class with the compared class. A. The result of a scholastic ability test High group had a great effect in the result of the first (Number and an expression) and second(An equation of a figure) scholastic ability test. As the time of research goes, the difference of average between the subjective class and the compared class has increased. Low group had no effect in the result of the first (Number and an expression) and the second (An equation of figure) scholastic ability test. But the difference of average grade between the subjective class and the compared class proved to be some efficient as time goes. (the first test is 0.94 and the second test is 3.33)We can find that the result of the third test (An exponent and log function) turned out be efficient. B. The change of mathematical attitudeHigh group had a great effect in confidence(+1.21), fiexibility(+1.92), will(-0.06), curiosity(+2.64), reaction(+1.50), value(+1.44). Low group appeared to be a little efficient in comparison between the subjective class and compared class. the average of both the subjective class and the compared class in low group decreased if not the result of pre-test but in that of pose-test. Therefore, we can find that the difference between mathematics of maddle school and that of high school gets bigger in Low group.C. The result of a question examinationAfter this research, the reaction that It is helpful to studying accomplishm- ent is 33.7%, the reaction that It is not helpful is 14.7%. After all, this research appears to be a positive reaction. After this study, the change of studying will seems to be much more not in Low group but in High group.