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위치 오차 최소화를 위한 가변 릴럭턴스 레졸버 최적 설계
강정문,최길수 대한전기학회 2024 전기학회논문지 Vol.73 No.1
The precision of position estimation in VR resolvers significantly relies on the harmonic components present in the induced voltage across the secondary winding. The degraded accuracy can be compensated by carefully designing the stator windings and core geometry. This paper presents an optimized design process aimed at minimizing the position error of VR resolvers. The alterations in the resolver output signal's position information, resulting from the phase shift of the stator windings, third harmonic injection-based rotor geometry modifications, and changes to the stator core shape, are thoroughly analyzed using finite element analysis (FEA). Subsequently, a genetic algorithm-based optimization technique is applied to construct an optimal design process that effectively minimizes the position error in VR resolvers. Case study results demonstrate an approximately 80% enhancement in position estimation accuracy for the optimal model compared to the initial model.
한국과 탄자니아 초등학교 과학과 교과서의 삽화 비교 연구
강정문,이용섭 대한지구과학교육학회 2014 대한지구과학교육학회지 Vol.7 No.3
The purpose of this research is to examine the current state of inserting illustrations in science textbooks under the 7th Revised Educational Curriculum which is currently enforced in all grades of elementary schools, and to compare and analyze the external and internal differences in illustrations in science textbooks of elementary schools in Tanzania and Korea to present desirable direction of producing illustrations. There are not only some differences in rate of the kinds and role of the illustrations in grades, but also in both countries. In Korea textbooks, Photographs were mainly used to guide the students into experiments and to train the students in analyzing and interpreting data. In contrast, the Tanzania textbooks place more emphasis on pictures to enhance their interests and curiosity and understand. The Korea textbooks have to place more various illustrations instead of photos but the Tanzania textbooks should place more photos. As a result the addition of more diverse forms of illustrations and the re-organization of illustrations according to the topic should be considersd in future Korea and Tanzania textbooks.
마인드 맵 활용전략 과학수업이 과학탐구능력 및 과학 학업성취도에 미치는 효과
강정문,이용섭 대한지구과학교육학회 2014 대한지구과학교육학회지 Vol.7 No.2
The purpose of this study was to examine the effects of science lessons using mind mapping on creativity and academic achievement in science. The subjects of this study were fifth-grade students selected from four classes of an elementary school located in Busan. For ten weeks, the experimental group of 40 students were taught using the mind mapping technique. The comparative group, also of 40 students, was taught in normal classes which used a standard text-book. Children were given a test on science processing skills and academic achievement in science to measure the effects of mind mapping. The Likert scales were used to gather student`s feedback on creativity and academic achievement in science. Through these procedures, the following results were obtained: First, mind mapping had a greater effect on science processing skills than the normal classes, where a text-book was used. Second, mind mapping was effective in improving the student`s academic achievements in science at a greater level than the normal classes where a text- book was used. Third, after viewing results of the Student Recognition Investigation, we found that the students showed a higher level of interest in science lessons that used mind mapping, and were better able to understand the scientific theories. As a result, the elementary science class with mind mapping developed greater science processing skills and saw higher academic achievement in science. We conclude that science classes that use mind mapping have the potential to develop better science processing skills and improve academic achievement in science.