• East Asian mathematical journal
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• v.29 no.2
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• pp.189-205
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• 2013

Addition problems can be divided into the 'problem of quantity' which does not have the concept of object or unit, and the 'problem of number' which have the concept of object or unit. 'Additive property' is the factor which has to be considered in the former case. On the other hand, 'additive property' is not considered and meaningless in the latter case. However, this additive property is not emphasized in the elementary curriculum that mostly deals with quantitative problems, so related errors are occurred in actual life. In this study, we will investigate to the pre-service elementary teachers through the problems of deciding the additive property. The result shows that the pre-service elementary teachers' cognition of additive problems is insufficient. This study will provide focal points in the teacher education and the elementary education, and the clues for the operating programs through the information about the tendency of errors.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.376-390
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• 2003

The contents of chemical reaction in the science textbooks, used by starting from elementary school to college level, were investigated how much closely connected with them. For this purpose, nineteen subjects of chemistry contents were selected and the articulation analysis, classified into 5 criteria, was carried out. The results indicated that the articulation from elementary school to middle school looked quite acceptable, but there was a big gap from middle school to high school and the articulation from high school to college exhibited a big overlap and gap. Finally, the flow map of chemical reaction was suggested.

• Journal of ILASS-Korea
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• v.16 no.3
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• pp.126-133
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• 2011

In HCCI Engine, combustion is affected by change of compression speed corresponding to engine speed. The purpose of this study is to investigate the mechanism of influence of engine speed on HCCI combustion characteristics by using numerical analysis. At first, the influence of engine speed was shown. And then, in order to clarify the mechanism of influence of engine speed, results of kinetics computations were analyzed to investigate the elementary reaction path for heat release at transient temperatures by using contribution matrix. In results, as engine speed increased, in-cylinder gas temperature and pressure at ignition start increased. And ignition start timing was retarded and combustion duration was lengthened on crank angle basis. On time basis, ignition start timing was advanced and combustion duration was shortened. High engine speed showed higher robustness to change of initial temperature than low engine speed. Because of its high robustness, selecting high engine speed was efficient for keeping stable operation in real engine which include variation of initial temperature by various factors. The variation of engine speed did not change the reaction path. But, as engine speed increased, the temperature that each elementary reaction would be active became high and reaction speed quicken. Rising the in-cylinder gas temperature of combustion start was caused by these gaps of temperature.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.163-164
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• 2003

Reaction dynamics plays an essential role in understanding the microscopic mechanism of elementary chemical processes at the molecular level. Detailed studies of the reactions of atomic species such as hydrogen and second-row atoms with small closed-shell molecules have provided important insights into hydrocarbon synthesis, combustion, interstellar space and atmospheric chemistry. Despite its mechanistic significance, however, the investigations of atom-radical reaction dynamics are quite scarce in comparison to the extensive studies of atom-molecule reactions. (omitted)

• Journal of Environmental Science International
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• v.17 no.9
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• pp.981-992
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• 2008

This study examined how to produce new methods of copper (II) sulfate crystallization by using a small-scale chemistry tool such as small-scale reaction surface and petri dish. The making of copper(II) sulfate is included in the 5th grade elementary science textbooks. Various copper(II) compounds were reacted with a 2 M sulfuric acid solution. The result of this study is as follows: Seven small amounts of copper(II) compounds were reacted with a few drops of 2 M sulfuric acid solution at room temperature to make a copper(II) sulfate crystal of triclinic shape. Using the petri dish method, a copper(II) sulfate crystal could be identified within one hour of reacting copper(II) hydroxide, copper(II) carbonate, copper(II) nitrate, copper(II) perchlorate, cupric(II) formate from a few drops of 2 M sulfuric acid solution at room temperature. When using the lap top method for copper(II) perchlorate, cupric formate, a proper crystal could be identified within one hour as well. SSC methods were used for the first time to make a copper sulfate crystal via chemical reaction. We can make a copper(II) sulfate crystal using a simple method which is easier, safer and saves time in class. And since a small quantity of chemicals are being used in SSC chemical methods, waste is greatly reduced. This lessens the amount of environmental problems caused by the experiment. This can be helpful in preserving nature. In addition the cost of chemical and laboratory equipment is greatly reduced because it uses material that we find in our daily lives. There will be continued study of small-scale methods such as improvement of new programs, study and training of teachers, and securing SSC tools. I would like to suggest such as SSC methods are applicable in elementary School Science. I would like it to become a wide spread program.

• Journal of the Korean Society of Combustion
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• v.19 no.1
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• pp.39-44
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• 2014

A short reaction mechanism for premixed $CH_4/CHF_3/Air$ flames was developed with a reduction method of the combined application of simulation error minimization (SEM) which included connectivity method and principal component analysis. It consisted of 43 species and 403 elementary reactions at the condition of less than 5% of maximum error. The calculation time operated with a short mechanism was over 5 times faster than one with a detailed reaction mechanism. Good agreement was found between the flame speeds calculated by the short reaction mechanism and those by the detailed reaction mechanism for the entire range of $CHF_3/CH_4$ mole ratios and equivalence ratios. In addition excellent agreements were determined for the profiles of temperature, species concentration, and the production rates of the various species. So the short reaction mechanism was able to accurately predict the flame structure for premixed $CH_4/CHF_3/Air$ flames.

• Journal of the Korean Society of Earth Science Education
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• v.6 no.1
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• pp.78-86
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• 2013

The purpose of this study is to analyze the effects of the Project based STEAM program on primary students' Problem solving process and creative personality. Based on the concept of project based learning and STEAM derived from a literature review, a learning program has been developed and applied to 28 elementary 4-6th students. Problem Solving Process and Creative personality tests were conducted before and after Project based STEAM program lessons. The results of this study are as follows. (1)Project-based STEAM was affected all components of problem solving process. (2) Project-based STEAM was affected all eight components of creative personality positively, (3) after using Project-based STEAM was good reaction by students. As a result, the elementary science class with Project-based STEAM had problem solving process for positive educational effect and creative personality. it means the science class with creative personality has potential possibilities and value to develop problem solving process and creative personality.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.1
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• pp.19-35
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• 2014

In this study, an experimental elementary school mathematics textbooks in use in the effects of the storytelling investigated. For this purpose, three different elementary schools teachers and students to a group of grades 3-4 mathematics textbooks for the effects of the storytelling questionnaire study. Survey, teachers were given an overall rating of storytelling in mathematics textbooks were positive recognition. Specifically, learning motivation and communication have significant positive recognition and learning of mathematics content that was helpful. The students are given an overall rating of storytelling textbooks showed a positive reaction. Grade 3 students were more positive than the four-year students. More specifically, mathematics is interesting storytelling. That public education was more fun than private supplementary education. But for storytelling low-level math students need measures showed insignificant changes.

• Korean Journal of Applied Biomechanics
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• v.29 no.1
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• pp.9-13
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• 2019

Objective: The aim of this study was to compare gait patterns of elementary school male students in higher grades according to their character styles. Method: 4 extroverted character male subjects (height: $141.35{\pm}7.75cm$, weight: $43.65{\pm}5.80kg$) and 4 introverted character male subjects (height: $145.38{\pm}8.94cm$, weight: $42.15{\pm}10.71kg$) participated in this study. Results: As for walk styles of elementary school male students in higher grades according to their character patterns, there was not significant differences in gait cycle, stride width, stride length and walking speed. According to examination of average ratio of maximum vertical ground reaction force according to their characters divided by weight, elementary school male students in higher grades with extroverted character showed 114.69% of weight and students with introverted character showed 122.82% of weight, which exhibited that students with introverted character had larger ratio as much as 8.13% than students with extroverted character. The statistical significance level was 0.000 showing significant difference. Conclusion: Our results indicated that male students in higher grades with introverted character press ground hard and walk with strong steps. On the other hand, male students with extroverted character walk with light steps.

• Journal of Korean Elementary Science Education
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• v.25 no.1
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• pp.96-108
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• 2006

The purpose of this study was to investigate how prospective elementary school teachers perceived teacher's inquiryoriented teaching practice, with an emphasis on students' scientific explanations based on scientific evidence. For this study, 94 prospective elementary school teachers were participated. 14 among 94 participants had chances to intensively experience this particular teaching methods for 15 weeks. All of the 94 participants observed the intended science teaching practice for 4th graders in two different elementary schools, which utilized the science talks emphasizing students' scientific explanation activity. For quantitative data analysis, they were asked to provide their reaction to the science teaching methods after their classroom observation. For qualitative data analysis, 5 among the participants, who had relatively long term experience with this teaching practice, were chosen to interview in order to understand their individual reasons of the ways they perceived about the inquiry-oriented teaching methods boosting students' scientific explanation. The results show that the prospective elementary teachers generally thought the emphasis of students' scientific explanation based on scientific evidence could enhance young elementary students' science content understanding, stimulate their curiosity/interests, and further develop their ability to engage actively in scientific discussions. However, some prospective teachers tended to think that the science teaching. methods would not be effective in terms of managing science classes, though. This study concludes that the prospective teachers tended to hold an endemic dilemma. On the one hand, they had their clear preference to the inquiry-oriented teaching practice as the most ideal teaching methods. On the other hand, they also had their persistent hesitance in using these methods due to their fear that elementary students might not adequately grasp the important science content when engaged in scientific discourse through an inquiry-oriented class.