• 항공우주시스템공학회지
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• 제9권1호
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• pp.1-6
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• 2015

A critical speed analysis of oxidizer pump was peformed for a 7 ton class liquid rocket engine as the third stage engine of the Korea Space Launch Vehicle II. Based on the previously developed experimental 30 ton class turbopump and presently developing 75 ton class turbopump for the first and second stage rocket engine of Korea Space Launch Vehicle II, a layout and configuration of the 7 ton class turbopump rotor assembly are determined. A ball bearing stiffness analysis and rotordynamic analysis are performed for both of the bearing unloaded condition and loaded condition. Structural flexibility of the oxidizer pump casing is also included to predict critical speeds. From the numerical analysis, it is confirmed that the rotor system acquires sufficient separate margin of critical speed as a sub-critical rotor even though decrease of critical speed due to the casing structural flexibility.

• 한국컴퓨터정보학회논문지
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• 제22권1호
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• pp.153-159
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• 2017

In recent years there has been a rise in the use and interest of the flipped learning as a teaching and learning paradigm. The flipped learning model includes any use of Internet technology to enrich the learning in a classroom, so that a professor can spend more time interacting with students instead of lecturing. In the flipped model, students viewed video lectures online outside of class time. Students then performed two kinds of assignments, a teamwork assignment and an individual work assignment, through the class time. In this paper, we propose a flipped educational model for a college class. This experimental research compares class of college algorithm using the flipped classroom methods and the traditional lecture-homework structure and its effect on student achievement. The result data of mid-term exam and final exam were analyzed and compared with previous year data. The findings of this research show that there was not a significant difference in the scores of student between two lecturing methods. The survey result and lecture evaluation by students show that students are in favor of the flipped learning.

• 대한지구과학교육학회지
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• 제4권3호
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• pp.231-241
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• 2011

The purpose of this study lies in finding out a betterment of ongoing experimental training program in science for the secondary science teachers to increase their training ability more effectively. For this, from 2010 July to September, a preliminary study on secondary science experiment training, questionnaire on the satisfaction of 128 secondary teachers in U metropolitan city with the training program were carried out which were contributive to the preparation of a better plan for the training program to be helpful for the teachers at schools. Following are the study results. First, the class theme should be selected by the teachers who participate in the experiment for the year to raise their training ability for experiment class. Second, the direct activity of the teachers' joining in experiment training for the development of experiment training module, and the demonstration with the developed module-used experiment class need to be included to the program Third, the assessment for the demonstration of experiment attitude, the development process of experiment training module, would be more advisable compared with that for written examination for the teachers joined in the experiment training to concentrate more on the experimental activities and to get richer experiment experience As this study results show, the theme selection, class method and assessment method involved in ongoing experiment training need for betterment for the science teachers to apply it at schools and this improved experiment training program proposed by this study is suitable for that under a condition it has to be modified and supplemented to the distinct features of every city and province.

• 정보교육학회논문지
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• 제16권4호
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• pp.451-462
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• 2012

본 연구는 초등수학 도형영역의 문제점을 해결하기 위한 방안의 하나로 초등학교 6학년 수학과 도형영역을 중심으로 현실세계에 가상 객체를 부가하여 학생 스스로 탐구하는 학습, 원리나 개념을 스스로 발견하게 하는 학습 객체를 만들었다. 본 연구에서 제안한 방법으로 서울 소재 M 초등학교 6학년 2급 학급을 선정하여 증강현실을 활용한 도형영역의 수업이 학생들의 학업성취도에 어느 정도의 영향을 미치는지 확인하기로 하였다. 그 결과 실험집단의 학습자들은 통제집단의 학습자보다 수업 흥미도 및 수업 만족도, 학업성취도에서 통계적으로 높게 나타났다. 이는 증강현실 도형 학습이 학습자에게 수업참여에 적극성을 가지게 하고, 도형 관련 개념 형성 및 학업성취도 관련이 있음을 알 수 있다.

• 초등상담연구
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• 제9권1호
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• pp.133-142
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• 2010

본 연구의 목적은 격려중심 학급운영이 초등학생의 학교생활적응과 자기격려에 미치는 효과를 탐색하는 것이다. 이를 위해 다양한 격려중심학급운영방안이 아들러의 개인심리학 이론에 기초하여 개발되었다. 연구대상은 광주광역시 A 초등학교 5학년 2개반이며, 한 반은 실험집단(n=28), 다른 한 반은 통제집단(n=31)이었다. 자료는 학교적응검사(강해련, 2008)와 자기격려척도(기채영, 홍경자, 2008)를 통해 수집하였다. 수집된 자료는 공분산분석을 하였다. 연구결과는 다음과 같다. 첫째, 통제집단보다 실험집단에서 학교적응점수가 유의미하게 증진하였다. 둘째, 통제집단보다 실험집단에서 지기격려점수가 유의미하게 증가하였다.

• 한국환경교육학회지:환경교육
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• 제22권3호
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• pp.83-96
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• 2009

This article extracted feasible elements for an environmental education program from the 'Intelligent Life', an integrated subject of the 7th elementary school curriculum, and designed a program for second graders in the elementary school and applied it to them in order to examine how the students' environmental altitudes changed. In the controlled class, the instruction followed the lessons specified in the 7th national curriculum faithfully while for the experimental class 1, only the inquiry activity-based environmental education program was applied. Moreover, in experimental class 2, the inquiry activity-based environmental education program was implemented and wrap-up activity was performed as well with the products. To verify the program, questionnaires on the change of environmental altitudes were distributed and analyzed total three times in the pretest, posttest 1(right after the program), and posttest 2(30 days after the program). T-test was carried out with the SPSS 12 program to verify the effect of the applied program. To make up for the quantitative analysis, qualitative analysis was also conducted. The followings show the results gained after the program was implemented. First, This program showed a significant difference(p<.05) in the students' formation of environmental altitudes. Second, it was verified that the inquiry activity-based environmental education class that reorganized the second grade elementary students' 'Intelligent Life' subject had a more positive effect in the cultivation of environmental altitude than the class that followed the present curriculum as it was. It will be necessary to perform follow-up researches on the relativity between curricula for kindergarteners and lower grade elementary school students.

• 정보보호학회논문지
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• 제27권6호
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• pp.1419-1429
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• 2017

최근 환경기반 인증 기술로 사용자의 로그인 히스토리를 계정도용 또는 정상 로그인으로 분류한 후 사용자별로 통계모델을 만들어 사용자를 인증하는 Reinforced authentication이 제안되었다. 하지만 Reinforced authentication은 사용자가 과거에 계정도용을 당한 적이 없으면 공격을 당할 가능성이 높다. 본 논문은 이러한 문제점을 해결하기 위해 기계학습 알고리즘을 이용하여 사용자 환경정보와 타인의 환경정보를 함께 학습시켜 2-Class 사용자 모델을 만드는 무자각 인증 기술을 제안한다. 제안한 기술의 성능을 평가하기 위해 목표 사용자에 대해 아무 정보도 없는 무 지식 공격자와 목표 사용자에 대해 한 가지의 정보만 알고 있는 정교한 공격자에 대한 Evasion Attack을 실험하였다. 무 지식 공격자에 대한 실험 결과 Class 0의 Precision과 Recall 각각 1.0과 0.998로 측정되었으며, 정교한 공격자에 대한 실험결과 Class 0의 Precision과 Recall 각각 0.948과 0.998로 측정되었다.

• 대한지구과학교육학회지
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• 제8권2호
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• pp.152-163
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• 2015

In this study, to raise the interest and curiosity of students and at the same time to learn science concepts meaningfully for students, the teaching and learning program was developed by applying the Frayer model. The purpose of this study was to find out the Effect of Elementary Science Teaching Program with Frayer model on Learning Motive and Learning Achievement. To this end, the 6th grade classroom of A-elementary school located in Seogwipo-city was selected the experimental group (26 patients). And the other 6th grade classroom in the same school was selected to the comparative group (27 patients). The experimental group was conducted applying the Frayer model. Comparison group has been conducted lesson program in accordance with the general science class teacher guide. Was through a pre-test of science learning motivation and academic achievement level can be assumed in the same group. After completing the experimental treatment by conducting a post-mortem examination was statistically validated. In this study, the following conclusions were obtained. First, elementary science class which applied Frayer model had the effect of to improve the scientific motivation. In particular, attention (p <.01), association (p <.01), confidence (p <.01) in the experimental group were higher than the scores of the comparative group, the difference was significant. Second, the Frayer model applied to elementary science class had a significant effect on improving science achievement. The experimental group which applied Frayer model was higher than the comparative group in science achievement post-test comparison. Between the groups showed a significant difference between the two groups (p <.01). The above findings, Elementary science class which applied Frayer model can be concluded to be effective in science and science achievement motivation. Therefore, applying the Frayer model of elementary science class could be useful in science teaching and learning methods. In addition, when it is determined through the previous study, applying the Frayer model classes will be able to derive a meaningful learning also subjected to a number of fields and areas.

• 대한수학교육학회지:수학교육학연구
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• 제8권1호
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• pp.73-87
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• 1998

Recently experimental class model is growingly recommended for mathematics instruction. Freudenthal(1973) points out the difficulties of learning probability and Fischebien suggested to teach probability more intuitively through games. However detailed explanations for such classes are not easy to find. This paper is to give more detailed materials for those lessons and to check its effectiveness. We give 6 topics of probability and statistics being taught in our middle school, such as histogram, concept of probability, probability calculations, expectations, standard deviations, and correlations and each of which is given along with the experimental materials to be used. We perform a trial of the methods and found some encouragement in the students' mathematical attitudes and interests but not in the achievements. We belive that the drawback of the achievement result is due to the short length of time of our experiments.

• 한국학교수학회논문집
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• 제3권2호
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• pp.155-164
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• 2000

The future society will demand that enables one to solve in many fields by connecting various informations in many fields and then creating his own information. In the coming society, creativeness will be regarded much important. This ability can be developed with materials through group activities experimental class in math classes. This classes using these materials are not teacher-oriented, explanatory classes but student-oriented ones. They offer students opportunities to think by themselves and expand their potential abilities. They are suitable for rising and keeping student's interests. Therefore experimental classes through group activities enable students to think mathematically and make them recognize the importance of mathematical approach by letting them work connecting other subjects or things in real life. They can develop not only expressive, communicative ability and cooperative spirit, but also the ability to transcend the class itself and then reorganize facts in new insights. Besides, math classes with experiments can arouse student's curiosity familiarizing them with mathematics. Moreover, they can expand student's originative and problem-solving abilities.