• Bulletin of the Korean Mathematical Society
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• v.52 no.2
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• pp.377-394
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• 2015

In this paper, we generalize some results about Bertrand curves and Razzaboni surfaces in Euclidean 3-space to the case that the ambient space is Minkowski 3-space. Our discussion is divided into three different cases, i.e., the parent Bertrand curve being timelike, spacelike with timelike principal normal, and spacelike with spacelike principal normal. For each case, first we show that Razzaboni surfaces and their mates are related by a reciprocal transformation; then we give B$\ddot{a}$cklund transformations for Bertrand curves and for Razzaboni surfaces; finally we prove that the reciprocal and B$\ddot{a}$cklund transformations on Razzaboni surfaces commute.

• Journal for History of Mathematics
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• v.26 no.5_6
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• pp.345-353
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• 2013

Some teachers do not regard the computation of the sum of the angles of a triangle by using a cut-and-paste or paper-folding method as providing a proof that the sum of the angles of a triangle is equal to two right angles. Some even think that this way of working is not mathematics but more like an experiment in physics. Some see the method as no better than measurement of the angles by a protractor. The author will examine this issue in the teaching and learning of school geometry and more generally as a specific example from the perspective of HPM (History and Pedagogy of Mathematics).

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.289-297
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• 2014

This paper proposed a novel high performance sensorless control scheme for IPMSM based on an extended nonlinear state observer. The gain-matrix of the observer has been derived by using state linearization method. Steady state errors in estimated rotor position and speed due to parameter inaccuracy have been analyzed, and an equivalent flux error is defined to represent the overall effect of parameter errors contributing to the wrong convergence of the estimated rotor speed as well as rotor position. Then, an online compensation strategy was proposed to limit the estimation errors in rotor position and speed. The effectiveness of the extended nonlinear state observer is validated through simulation and experimental test.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.721-723
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• 2015

Astronomical outreach activities for the general public who are unfamiliar to astronomy is a challenging task. It requires creative thinking to solve the problem. The amateur astronomical clubs in a number of cities in Indonesia routinely schedule observations at public parks. The interaction between these clubs and formal education institutions is established by face to face interaction and assisted by social media. The physics teachers who took astronomy courses in university are potential resources to enlarge the outreach scope by creating astronomical clubs as an extracurricular activity. Recent progressive trends in astronomy dissemination for the disabled are also a great opportunity to assist the disabled in experiencing hands-on activities based on formal and informal education.

• Journal of The Korean Association For Science Education
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• v.33 no.2
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• pp.345-358
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• 2013

In this study, we investigated the current status of the teacher education curriculum and the recruitment of general science teachers, and the ways to improve them as suggested by Professors from the Department of Science Education. Most science education departments have not required double majors in general science, and there are wide differences in the number of students who take the general science programs. There is not any department that requires science courses other than its own science major courses when students get only their own in-depth science major certificate. A few departments provide integrated science courses such as history of science, scientific creativity, integrated science, and so forth. Most professors revealed negative perceptions toward 'a compulsory requirement of double majors in general science' with other in-depth science majors such as physics, chemistry, biology, and earth sciences. The majority of professors also suggested providing elective courses in integrated science-related subjects. Regarding general science majored teacher employment, most professors did not agree with separate employment for the general science teacher, although they agreed with the necessity of the general science teaching certificate. They also suggested that preservice teachers need to take science courses other than their own specialized science majors for the in-depth science teaching certificate. Based on the results, we suggested ways to improve the teacher education curriculum and the recruitment of general science teachers.

• Journal of The Korean Association For Science Education
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• v.24 no.3
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• pp.532-543
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• 2004

The teacher appointment examination is consisted of a written test, an interview, a demonstration of teaching practices, one's academic record etc. The primary written test(full credit of 100) consists of multiple-choice test of general pedagogy(30%) and constructed response test of science(70%). The science test consists of science education($20{\sim}30%$) and science content($70{\sim}80%$). Five science exams were implemented for appointing general science, physics, chemistry, biology and earth science teachers in 2002 and 2003. The credits alloted to science education domain decreased from $25.7{\sim}30%$ in 2002 to $24.3{\sim}25.7%$ in 2003. The percentage of correct answer was similar between science education and science content domain in 2002, but the percentage of correct answer in science education domain(70.2%) was 29.8% higher than that of science content domain in 2003. Earth science exam almost reached the target mean score of 60 but the other four exams showed the mean scores ranging from 45.0 to 52.7 in 2002 and from 40.1 to 49.6 in 2003. The percentage of high difficulty items(p<40%) was 41.2% in physics and chemistry in 2002, 50% in physics and chemistry, and 45% in biology in 2003. Seventy eight percent of the items showed fairly high discrimination index(r>.30). In addition, the reliabilities of 5 tests were from .79 to .88. In conclusion, it is recommended that the credits alloted to science education domain should be increased up to 30%, and exam difficulties should be lowered to a proper level by making science content items easier.

• Journal of Science Education
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• v.33 no.2
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• pp.165-172
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• 2009

Korean 7th national curriculum gave the right to elect the advanced subject such as physics II, chemistry II. Students could elect the subject by their aptitude and interest. But, actually, the choice was constrained by school circumstances such as the number of teacher and the number of class. high school students. We investigated the demand about school science and perception about scientifically specialized high school in which the students could have all advanced science subjects by the survey of 336 middle school students including 148 students in the science education center for the gifted, 220 high school students, and 70 science teachers in capital region. As results of this study, most of the high school opened chemistry and biology advanced subjects, but only 37.1% of them opend physics advanced subject. This constrained students' right of elect the subject by their interest. While most of middle school and high school students normally demanded the more experiment in the class and the easier science content, the students in the science education center for the gifted demanded more science class time. The students who wanted to have science career had very positive recognition of scientifically specialized high school and science teachers agreed to running the scientifically specialized high school.

• Journal of Korean Elementary Science Education
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• v.23 no.1
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• pp.27-36
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• 2004

This paper aims to examine how well university students, who are going to be primary school teachers, understand the International System of Units (SI), focusing on seven basic units such as 'm', '㎏', '㏖', 'A', 'K', 's', 'cd'. This study specifically investigates whether the students know the seven units and understand their uses and how they read and learn them. The subjects were 1030 students from the University of Education in Jinju, Geongsangnamdo. Data was collected through a questionnaire which was designed by this researcher and checked by an authority, and the frequency and percentage of reponses to each question were obtained and analysed. Findings show all the students knew very well that 'm' and '㎏' are included in the seven units, compared to the others which low percentage of the students considered as the elements. In terms of understanding of use, the units of the length 'm', the mass '㎏', and the time 's' are well understood, presumably, because they are often used in ordinary life and school, while the amount of substance '㏖', the electric current 'A', the thermodynamic temperature 'K', and the luminous intensity 'cd' are not as well understood. It is probably because 'A', 'cd', and 'K' are hardly used in everyday life. With respect to reading the units, the subjects read 'm', '㎏', '㏖', and's' much better than the others. As for the source of learning them, most students answered they learned them in schools, which implies school education is very important. From these results it is concluded that school education should be accompanied with use in everyday life for understanding and using the units. SI Base Units understanding was investigated by an academic year. According to this investigation, generally the right answer rate differed 4<2<3<1 by an academic year in order. For the Senior, Sophomore appeared the right answer rate more high. because, they learned before in deepening or elementary course on chemistry and physics related with SI Base Units. On the other hand, for the junior answered low rate by this reason that they couldn't remember about SI Base Units that learned before. For the Freshman appeared low rate by this reason that they were not learned or graduated from the department of liberal art in high school.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1249-1261
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• 2018

The quantitative representation for the magnetic force of a cylindrical permanent magnet acting on a ferromagnetic cylindrical object was derived on the basis of magnetization theories, and the Gilbert and Ampere models of magnetism. The magnetic force derived in this study is directly proportional to the remanent magnetization magnetic field, the cross-sectional area of the permanent magnet, the saturation magnetic field, and the cross-sectional area of the ferromagnetic object and is inversely proportional to the square of the quantity related to the distance between the permanent magnet and the ferromagnetic object. The magnetic forces of an AlNiCoV cylindrical permanent magnet and a Ferrite cylindrical permanent magnet, both with a radius of 0.4 cm and a length of 7 cm, acting on ferromagnetic objects at distances farther than the radius were calculated to be less than 3.6711 N and 0.1857 N, respectively.

• 대한공업교육학회지
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• v.32 no.1
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• pp.73-92
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• 2007

The purpose of this study was to develop ICT(Information and Communication Technology) teaching-learning materials for motorcycle safety education. Physical subjects which are relevant with motorcycle dynamics were introduced to increase the safety awareness through integrated learning such as the combination of technology and science. The results of this study were as follows : (1) Utilizing the physics basic theories which are relevant to motorcycle dynamics, the lesson plan of motorcycle ICT teaching-learning materials, which were included to plan and instruction action plan, was developed. (2) Flash animation or movie was developed to apply physics knowledge to technology in driving motorcycle. This is able to improve the attitude of driving motorcycle of students. (3) Through the contents of appendix of motorcycle safety driving section in this web-site developed here, junior and senior high school students would be able to strengthen their cognitive domain of motorcycle by themselves. (4) Using the web-site of this study, both teachers and students would be able to freely interact through an online bulletin board.