• Journal of The Korean Association For Science Education
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• v.26 no.6
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• pp.753-764
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• 2006

The concept of blood circulation is so complex, dynamic and abstract that students have difficulty in understanding it and students' preconceptions hardly change into scientific concepts even after the lessons. The purpose of this study is to examine middle school, high school, and undergraduate students' understanding of blood circulation and to find the reason why the lack of deep understanding is displayed in students' explanations for the blood circulation. The study consists of three parts. First, the test was designed to investigate students' ideas for blood circulation as components of the structure, the function, the behavior and the mechanism. Second, the test was applied to 7th, 10th and 13th graders to investigate the students' understanding of blood circulation and categorize the types of students' blood circulation model according to their academic level. Finally, the concepts the students had little understanding of were analyzed to decide which ontological category they fell into and further to inquire the characteristics of each concept. The results showed that many students comprehend the structure and the function of blood circulation components well, and there was no significant difference in students' understanding according to the academic level. In contrast, understanding the behavior and the mechanism of circulatory components has remarkably improved in high school students and undergraduates majoring in science and engineering. Also, students' blood circulation models were classified into seven different types. High school students and undergraduates majoring in science and engineering demonstrated a significantly higher percentage on the type of double-loop-branch compared to other academic levels. In addition, it was found that the lack of deep understanding was caused by students' misconceiving the 'equilibrium' category as 'event' category.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.57-67
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• 2008

At present engineers use the highway design speed concept to develop the horizontal alignment. This concept has a strength of attaining consistent horizontal alignments because of its use of a single speed value. Yet it shows a critical weakness that when opened the operating speed for the vehicles on the road can be a lot different than the design speed. To resolve this, many countries already develop the horizontal alignment by adopting procedures that weigh vehicle operating speeds, and this research joins them by developing an operating speed based horizontal alignment design. We have collected vehicle speed samples over the nation, selected some speed influential design elements by doing a statistical analysis, provided a set of models for two-lane roads and four lane roads, and showed a stepwise feedback procedure by doing a case study. It is underscored that in the case study the proposed procedure has scaled down the speed inconsistency problem, and we are of opinion that our procedure would coin both investment efficiency and speed consistency in future highway projects.

• Journal of the Korean School Mathematics Society
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• v.6 no.2
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• pp.117-126
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• 2003

In this article, we described students' conceptions of fraction, based on the mathematical learning theory of Skemp who contributed to the understanding of a mathematical conception in the real world problems. We analyzed students' responses to given three problems in order to examine a degree of the conceptual understanding in their responses. In conclusion, it suggests some instructional methods which facilitate students to understand the conceptions the fraction implies.

• Korean Security Journal
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• no.21
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• pp.53-74
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• 2009

The fatigue of the Private Security Guard, such as the increase of demanded conditions, are increasing by the change of environment of inside and outside of the Society. Private Security Guard unable to solve the problem of fatigue created by their tasks has high possibility of jeopardizing their associated and citizens as well as themselves. Furthermore, fatigue can also have not good effects on Organization in various aspects. Accordingly, the problem of Private Security Guard's fatigue has significant meanings especially on effectiveness of the Organization. So this study is performed to provide implications for Private Security Guard's life quality grows by grasping not only influence that fatigue has on job attitudes, and whole relation among fatigue, Turnover Intention and Job Satisfaction that are consequences of fatigue. The private security companies of their Turnover Intention and job satisfaction from the job to the significant influence of, Dae-Jun Chungnam Province and the 215 Private Security Guards working in 20 companies. This following the summary of this study in the relation between perceptions on fatigues and Turnover Intention and Job Satisfaction, perceptions on fatigues influences on Turnover Intention.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.99-100
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• 2006

철도안전법의 제정 및 시행에 즈음하여 철도안전관리에 대한 인식이 제고되고 있는 시점에서 인적요소를 고려한 전기철도안전관리기법을 제시한다. 이를 위해서는 인적신뢰성분석이 필요하나 현재로서는 세계적으로도 이에 관한 규격이 정비되어 가고 있는 실정으로서 국내에서는 규격 적합성 인증 제도가 아직 구축되어 있지 못하고 따라서 규격 정비의 진행에 따라 위험성정보교환에 관련된 대책의 필요성이 증가하고 안전성의 확률론적 정량적평가가 보다 중요시 될 것으로 예상된다. 본고에서는 시스템 위험도분석을 통한 안전공학적 절차를 준수함으로써 위험도를 정량적으로 평가하고 정량적으로 평가된 위험도를 적정 수준으로 관리함으로써 철도시스템 안전관리체계를 향상시킬 수 있는 기법으로서 최근 주목받고 있는 인적신뢰성분석기법과 위험도정보교환에 대한 기본 개념을 제시한다.

• Journal of the Korean School Mathematics Society
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• v.20 no.2
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• pp.77-89
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• 2017

Although it is not necessary to have much mathematical knowledge in Major Courses of Animal Resources curriculums in agricultural high school, the function of mathematics class has a much effect on Major Courses. Therefore, we extracted the mathematics contents included in Major Courses of Animal Resources curriculums in agricultural high school, and also evaluated students' understanding according to the description method in textbooks of Major Courses. Furthermore, we analyzed students' preference about the description method in textbooks related to the Major Courses. As a result, it turns out that the level of mathematics contents of Animal Resources major curriculums does not break bounds of middle school level. Furthermore, many students are not able to solve the middle school level of problems. It is also shown that the most preferred description method in textbooks of Animal Resources major curriculums is the sentence-equation mixed type. In this study, we propose to reconstruct the mathematics contents with basic knowledge needed to complete the Major Courses in order that students can complete them more easily, and furthermore, to choose the description method in textbooks of Major Courses as sentence-equation mixed type and detailed explanation about terms should be included into the bargain.

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1273-1284
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• 2013

The purpose of this study was to analyze the examples represented in school science textbooks by the function types for students' scientific conceptions. According to the framework of analysis, we selected lacking examples in the textbooks, and developed a questionnaire for students. The questionnaire was applied to 157 third grade students to survey their conceptions related to matter states and change of states. The ratio of students' scientific conceptions related to solid the state was high because distinct examples were represented in the textbook. However, the ratios of students' scientific conceptions related to the liquid and gas states were low because there were no distinct examples in the science textbook. Contrast examples and expansive examples of liquid and gas such as fog and steam need to be represented in science textbooks in order to help students construct scientific conceptions of matter states and change of states.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.478-487
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• 2014

The simplified performance analysis and initial configuration design are required for the successful development of UAV during the conceptual design, in which empirical formulas and trend equations are utilized for the UAV performance analysis. In the conceptual design phase various UAV configurations may be considered, however, it is very inefficient and unnecessary to consider all configurations for the conceptual design. In this study, the database for the fixed wing UAVs whose MTOW is between 50kg and 1,500kg was also constructed for the selection of configuration frequently used. The parametric analyses were performed for major performance parameters, and trend equations were developed through regression analyses for these individual performance parameters.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.753-762
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• 1998

This Paper reports results of investigating the relationship between students' perfoonance and mathematics imtructiooal system in understanding of the function concept. A written examination measuring calcullli students' understanding of the fimction concept was administered to two groups of students whose educatiooal oockground were different. One group consists of students who completed a pre-calculus course in Korea and the other group completed the same course in the United States. This study investigates how students in two groups acquire an understanding of major aspects of the function concept and provided interesting insights regarding the different background and belief related to their performance. Follow-up interviews were conducted to identify possible explanations for the different performance of the two groups in understanding the function concepts. Results indicate that the differences came from the educational environment and individual belief.

• Korean Journal of Childcare and Education
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• v.11 no.4
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• pp.19-37
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• 2015

The purpose of this study was to examine early childhood teachers' knowledge and the level of their knowledge on the contents of early childhood nutrition education. The subjects were 105 early childhood teachers and they were asked to draw a concept map. The number, characteristics and density of superordinate concepts on the contents of early childhood nutrition education were analyzed. The results were as follows: Firstly, the most frequent superordinate concept was dietary habits. Secondly, food culture was the highest average of the number of subordinate concepts. In a hierarchy, food culture was also the highest score. In specificity scores, food was the highest score. And the density ranged from 0.33 to 3.60. In conclusion, the teachers' knowledge structure on early childhood nutrition education could be regarded as parallel, not well-integrated, rather than hierarchical or well-organized. A variety of nutrition education and customized teacher training should be provided for early childhood teachers to offer early childhood nutrition education.