• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.344-347
• /
• 2009

Surge protective devices (SPD) have a special position because of the expectation that they perform an effective protective function against various kinds of surges. However, there exists a misconception that the SPD satisfying lower measured limiting voltage (MLV) should also protect equipment against temporary overvoltages (TOVs) as well. This paper inspects various types of MOV based SPDs and carry out experiments on the side effects of the low MLV characteristics. The experiment results show that a low MLV could cause a higher TOV-induced SPD failure rate in the field.

• Journal of The Korean Association For Science Education
• /
• v.23 no.6
• /
• pp.660-670
• /
• 2003

This study examined the conceptions of high school students, In-service chemistry teachers, and chemistry teachers related to the electrolysis phenomena by questionnaires and follow-up interviews. High school chemistry II textbooks were analyzed for finding the cause of the misconceptions of the teachers and students. From the analysis, it was found that many teachers represented to students the reduction-oxidation reaction and the electrodes of electrolysis are opposite to the reaction of a chemical cell without explanation of the principles. It means that students would learn the electrolysis phenomena by rote. But the teachers thought that it was not necessary to explain the principles to students because the students could not understand. Also, some of the teacher had misconceptions in electrolysis of solution taking no account of water electrolysis. They only considered the reduction-oxidation reactions of the ions already were contained in solution. They did not considered the ions generated by the electrolysis. This tendency is similar to In-service chemistry teachers and high school students. Also, this tendency can be found in chemistry II textbooks.

• Journal of The Korean Association For Science Education
• /
• v.10 no.1
• /
• pp.57-64
• /
• 1990

In this study, novices' protocols were investigated on the basis of Mayer's analysis of mathematical problem solving. These protocols were obtained by Jae-Sool Kwon and Seong-Wang Lee(1988) by means of thinking aloud while 20 sophomore students in a department of physics education were solving physics problems on Newton's low of motion. The results of investiqation are as follows; (1) We proposed an effective method in analyzing protocols on physics porblem solving (2) We could find the defective types of knowledge of individuals who got an incorrect solution, through analyzing the cause of failure individually (3) The fact that many students considered first the frictional force as muntiplying the coefficient of friction by perpendicular force rather than as resistance of motion, was found And students' misconception on the coefficient of friction was found. (4) If such analyses of test items and protocols are used in physics education, they will be very useful for finding the faults of problem-solving process, and for setting and scoring subjective problems in physics

• Journal of The Korean Association For Science Education
• /
• v.22 no.4
• /
• pp.683-695
• /
• 2002

In this study, we analyzed types of explanation on osmosis concept that were represented in chemistry and biology textbooks of high school and college. There were 5 types of explanation on osmosis concept. The types of explanation were diffusion of solvent, collision, hydration, equilibrium of concentration and screen of holes. Last two types of explanation were classified into misconceptions. The various types of explanation on osmosis concept might cause to have be a reason that students had many misconceptions and to feel difficult to learn about osmosis concept. Many of textbooks is accord to types of concept explanation and figure explanation on osmosis but some is not.

• Journal of The Korean Association For Science Education
• /
• v.16 no.1
• /
• pp.61-76
• /
• 1996

The purpose of this study was to apply the instructional strategies for conceptual change prescribed by Posner et al(1982) to the astronomic content domain taught in the elementary and middle school and to analyze the characteristics of students' knowledge revealed in the test before, during and after the instruction. Also, it was to investigate the intercorrelation of cognitive levels, spatial ability and science achievement. The major findings of this study are as follows: 1. Students had a great variety of misconceptions related to the motion of the moon before the instruction, that is, the phases, the names of phases and the cause of changing phases by the moon's orbit about the earth, the moon's appearance and location at the given time, the relative positions of earth, moon and sun during a lunar eclipse, the cause that a full moon is not at the line of node once a month. In the analysis of students' responses concerning the cause of changing phases of the moon and a lunar eclipse, the results indicate that the great majority of students had rote learning rather than meaningful learning in the middle school. 2. Students' reponses during the instruction concerning the changing phases of the moon and the predictive knowledge about the motions of the earth and the moon were analyzed. 1) According to the results of the test given before and after experiment, after discussion, achievement score of the whole of subjects and groups in both preformal and formal cognitive levels appeared to increase linearly. 2) There was no statistically significant differences of achievement scores before and after experiment, after discussion between preformal group and formal group in cognitive levels. 3. Distribution of achievement scores according to the whole of subjects and groups in preformal and formal cognitive levels shows that there was a statistically significant difference between pretest and posttest. 4. Types of conceptual changes concerning the cause of changing phases of the moon that occurred from pretest to posttest were classified as accommodation, incomplete accommodation, assimilation, no change and no model. Six of the seven students starting instruction with alternative frameworks didn't sustain those alternative models throughout instruction. Five of these six students accommodated completely and the last one partially. Seventy-nine percentage of students taking instruction with fragmental models assimilated correct propositions at the end of the instruction. These results suggest that conceptual change model prescribed by Posner et al(1982) has promised the meaningful learning to students taking with fragmental models, especially in cases where students with misconception enter instruction. 5. High correlation between achievement score of simple-recall items and that of written items in pretest and posttest indicates that the higher students got the score in simple-recall items the better they also performed in written items. However, there was no statistically significant differences among cognitive levels, spatial ability and science achievement in the whole of subjects and groups according to the cognitive levels.

• Strategy21
• /
• s.44
• /
• pp.213-253
• /
• 2018

The Russo-Japanese War(1904-1905) in the early 20th century greatly influenced the international politics in Northeast Asia and the destiny of both countries. There are many studies on the cause of the outbreak and its effect on the Korean peninsula. The victory and defeat of the battle of Tsushima also the subject of research by renowned scholars and navy officers. Many previous studies have analyzed the process of engagement. However, There was a lack of research that analyzed at the tactical level of naval commanders. Therefore, this study tries to review the battle of Tsushima in terms of tactical level, that is formation, maneuvering, damage control. Naval operations at sea with many variables are not always done as planned. The intuitive judgement and readiness have had a decisive impact on victory and defeat. The analysis of the naval warfare on the basis of formation, maneuvering, and damage control makes the cause of the win more clearly. The conclusion of the this study can be summarized in five ways. First, victory would be achieved through the suppression of the beginning. The destiny of the Tsushima battle was determined by an 1 hour after first firing. The Japanese fleet caught fire by paralyzing the command and control capabilities of the Russian fleet. Second, the Japanese fleet's power was superior to the Russian fleet. In general, Japan and Russia had similar powers, and Admiral Togo's "T crossing tactics" decisively contributed the victory. However, when compared to the weapon system level, formation and maneuvering, Japan was much more dominant. Third, people realized that one side to be annihilated in the battle between similar powers after the Tsushima battle. The common perception before the Battle of Tsushima was that the battle ship would not sunken, and that the result of wiping out was difficult. However, there is s time for one sided victory and defeat depending on the early suppression nad the destruction of the command and control ability. Fourth, it is the importance of damage control ability. The main cause of the Russian fleet's loss of command and control ability was thick smoke from fire, and maneuverability was greatly deteriorated due to coal overload. In this way, importance is still valid after more than 100 tears. Fifth, the area of uncertainty. In the navy battles, one or two shots of clear firing in the beginning and small misconception and minor mistakes decide win or loss. Ultimately, this area of fortune can be linked to mindset of the commander. I hope this research will be help to naval researchers and naval commanders at the sea.

• Journal of The Korean Association For Science Education
• /
• v.24 no.3
• /
• pp.544-555
• /
• 2004

This study examined the conception types of high school students, chemistry teachers, and pre-service teachers about the salt bridge in Daniel cell by a questionnaire and follow-up interviews. High school chemistry II textbooks were analyzed for finding the cause of the understanding difficulties of the teachers and students. Pre-service teachers' thoughts examined for the problems of pre-service teacher programs. From the analysis, it was found that teachers only thought that the role of salt bridge is for ion movement of two solutions involving electrodes. But they didn't have the conception that salt bridge has a roll of connection a circuit. This result was similar to students' and pre-service teachers' results. It was possible that insufficient and different explanations of the textbooks were attributed the teachers' and students' conceptual difficulties.

• Journal of Korean Elementary Science Education
• /
• v.27 no.4
• /
• pp.385-398
• /
• 2008

The purpose of this study is to understand the effect of The Model of Phases of the Moon on conception changes for preservice teachers. The researcher interviewed two preservice teachers under the agreement with them on their participation in the research just before he performed a class using The New Model of Phases of the Moon. The post-interview with the same content as the pre-interview was preformed one month later. The main content of the interview is as follows; 'Explain the shape of the Moon by drawing it.', 'Explain the relative different position among the Sun, Earth, and Moon depending on phases of the Moon by drawing them.', 'What do you think of the cause of phases of the Moon?', 'Draw a picture to explain why we always see only one side of the moon.' The results of the research are as follows. First, the class with New Model of Phases of the Moon was able to perceive the relationship of Sun, Earth, and Moon in three-dimensions rather than in two-dimensions and it helped to change their misconception that the Moon's shadow causes the Moon's shape. Secondly, the class with New Model of Phases of the Moon helped preservice teachers understand better the different positional relationships among the Sun, Earth, and Moon depending on the Moon shapes. Third, the class adopting the New Model of Phases of the Moon help preservice teachers form scientific conceptions on the causes of phase change of the Moon. Fourth, the class with the New Model of Phases of the Moon is not appropriate for explaining the reason why only one face of the Moon is seen. Based upon the results above, the researcher realized the limitation of this model and suggested that this model would help learners understand phase change of the Moon and increase space perception ability.

• Journal of Science Education
• /
• v.36 no.2
• /
• pp.369-380
• /
• 2012

The purpose of this study was to investigate middle students' conceptions of buoyancy. The questionnaires composed of 9 items which asked the reasons for situations with buoyancy; recognized of buoyancy, the facts affecting buoyancy(bottom of the Area of the object, the shape of the object, the depth of the object in the water, amount of water, the degree of the object submerged in the water, volume of the object, weigh of the object), the relationship between the amount of replaced fluid and buoyancy. The subjects were 140 students from the Busan Area who answered questionnaires composed of 9 items which asked the reasons for situations with buoyancy. Among the 140, 132 students were selected who answered all of question in the test. The students' answer types were follow: 1. Related to the shape of the submerged object, students answered that buoynacy depended on the bottom dimensions or the surface area of the object. 2. Students confused press, water press and buoyancy, who answered buoyancy was great when the water press was great. 3. Students answered that the weight and the size of the buoyancy of the object was same in the water. 4. Students answered, gravity was smaller in the water. Students recognized the existence of buoyancy but the reason of the answer depend on their experience. Also students answered using the words that water pressure, pressure, force instead of buoyancy. Students didn't understand the factors affecting the buoyancy. Many students responded that buoyancy was changed depend on weight of object, sinking depth, shape and others. It was considered that these responses didn't understand the cause of buoyancy.

• Journal of The Korean Association For Science Education
• /
• v.25 no.2
• /
• pp.88-97
• /
• 2005

The purpose of this study was to investigate explanations of science textbooks and science teachers' conceptions related to freezing point depression phenomenon. Seven kinds of middle school science textbooks and five kinds of high school chemistryII textbooks were analyzed for the purpose. The teachers' conceptions were searched by a questionnaire developed in this study. The subjects were 146 science teachers. The explanation types of science textbooks were divided into two; 'Description of the phenomenon' and 'Vapor pressure lowering'. The explanations in most of middle school science textbooks and high school chemistryII textbooks belong to 'Description of the phenomenon' and there was no explanation of the reason. The graphs related to depression of freezing point were diverse, too. Most of the science teachers also did not have scientific conception. The percentage of the teachers who thought that the cause of freezing point depression was blocking of solute in solution was high. But the teacher could not find meaningful relation the 'Blocking of solute' explanation represented for elevation of boiling point with depression of freezing point. It is insisted that entropy concept is need to explain depression of freezing point phenomenon in this study.