• Journal of The Korean Association For Science Education
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• v.22 no.4
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• pp.796-805
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• 2002

This study examined the knowledge structure constructed by children before formal instruction, and successive changes in the structural complexity of knowledge during and after the learning of 'Structure and Function of Plant' unit. It also investigated how those changes were affected by children's learning modes. The researchers made the 5th graders draw the first draft of their concept map to see the pre-existing knowledge structure concerned with the unit and four more concept maps after completing every fourth lesson. And to see how long their knowledge structures were preserved, the researchers made children draw additional concept maps in 3 days, 3 months, and 7 months after completing the unit. Children drew their current concept maps on the basis of the previous one while learning the unit and without the previous one after completing the unit. Each concept map drawn by children showed the degree of their current understanding on the structures and functions of plants. The results revealed that only two levels of hierarchy and five relationships among the components of the first concept map(relationship, hierarchy, cross link and example) were proven to be valid in terms of conceptual relevance. Growth in the structural complexity of knowledge took place progressively throughout the unit and the effects of learning mode on the growth were favorably reflected in concept map scores of meaningful learners over time(relationship, cross link, example: p<.01, hierarchy: p<.05). Although there were some differences on the concept map scores between two types of learners, they commonly showed that knowledge restructuring had occurred apparently in the early periods from the 1st to the 6th lesson and had not occurred at all in the last period of the unit. The frequency of tuning was higher in rote learners than in meaningful learners throughout the unit, but the frequency of accretion was reverse. Concept map scores of rote learners constructed in the course of learning of the unit decreased little by little gradually in all the categories after completing the unit. However, the average total map score of meaningful learners increased a little more in 7 months than in 3 months after completing the unit. Therefore it can be inferred that meaningful learners construct more stable and well-differentiated knowledge structures than the rote learners.

• Journal of The Korean Association For Science Education
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• v.19 no.4
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• pp.665-673
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• 1999

We examined how science teachers in middle schools practiced and perceived using analogies. A survey was administered to obtain 131 teachers' responses from 22 middle schools in Seoul. Most science teachers used analogies frequently in their instructions, and had positive attitudes toward the effect of analogies. They agreed that relevant figures should be presented with analogies, analogy itself should be explained to their students, and something to mislead the students' idea should be mentioned. They also responded that they practiced so in their instructions. However, it was revealed that they neither explained a concept with several analogies nor helped students to make self-generated analogies. Their idea was that proper analogy sources and instructional models were needed for using analogy effectively in science instruction. The teachers with above masters degree explained the analogy itself, and they perceived the needs for supplements and strategies in using analogy more affirmatively. The teachers possessing modern perceptions to science instructions and students' activities rather than classical ones used analogies more frequently and effectively.

• Journal of Computing Science and Engineering
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• v.5 no.2
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• pp.121-130
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• 2011

Recent research indicates that transient errors will increasingly become a critical concern in microprocessor design. As embedded processors are widely used in reliability-critical or noisy environments, it is necessary to develop cost-effective fault-tolerant techniques to protect processors against transient errors. The register file is one of the critical components that can significantly affect microprocessor system reliability, since registers are typically accessed very frequently, and transient errors in registers can be easily propagated to functional units or the memory system, leading to silent data error (SDC) or system crash. This paper focuses on investigating the impact of register file soft errors on system reliability and developing cost-effective techniques to improve the register file immunity to soft errors. This paper proposes the register vulnerability factor (RVF) concept to characterize the probability that register transient errors can escape the register file and thus potentially affect system reliability. We propose an approach to compute the RVF based on register access patterns. In this paper, we also propose two compiler-directed techniques and a hybrid approach to improve register file reliability cost-effectively by lowering the RVF value. Our experiments indicate that on average, RVF can be reduced to 9.1% and 9.5% by the hyperblock-based instruction re-scheduling and the reliability-oriented register assignment respectively, which can potentially lower the reliability cost significantly, without sacrificing the register value integrity.

• School Mathematics
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• v.12 no.3
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• pp.411-424
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• 2010

The fractional concept consists of various meaning, so that it is difficult to understand in primary school mathematics. In this article, we intend to analyze the cognition of 54 pre-service elementary teachers about the operations of partitioning and iterating that are based on Steffe's fraction schemes. The following fraction problem is used in this analysis: If the bar $\Box$ represent 3/8, then create a bar that is equivalent to 4/3. In our analysis, the 43% of pre-service elementary teachers can be well to treat the operations of partitioning and iteration. The 33% are use the equivalent fractions. But the 19% is not good. From the our analysis, it is important that pre-service elementary teachers must be have experimental(operational) thinking as the science education. And in this study we apply the operations of partitioning and iterating to the fraction activity of textbooks.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.663-677
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• 1998

The development of Science and Technology and the social change require new paradigm in Education. In a traditional paradigm, learners have been regarded as a passive being and knowledge could be transmitted to learner. But within this paradigm, it is difficult to confront the social change and to develop problem solving skills in various context. This results in a new, alternative perspective, Constructive paradigm. As an alternative to the traditional settings, Constructive paradigm emphasizes the learner centered instruction. The reform movement in mathematics education including NCTM's standards revolves around this paradigm and the open education movement in our educational system is based on it. Open education values learner's interest, autonomy and internal motivation in learning. However, open education has been misunderstood by most of the teachers. It should be understood as the change of paradigm. In this study, as a way of helping students connect mathematics to their everyday lives and construct meaningful mathematical knowledge and concept, mathematical modelling is suggested. It consists of posing and specifying the real problem, formulation and constructing a mathematical model, analyzing and solving a mathematical problem. interpreting the solution and comparing with reality and communicating results. In this process, technology like computer can be a powerful tool. It can help students explore various problems more easily and concretely.

• Journal of Engineering Education Research
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• v.26 no.6
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• pp.19-29
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• 2023

This study aims to develop and apply a metaverse-based instructional design model for the education in science and technology. It analyzed the concept and characteristics of metaverse, existing non-contact education models, and major teaching strategies systematically. Based on the prior researches, an instructional design model using metaverse is developed that presents metaverse-related teaching strategies and design principles for the before-, during-, and after-lesson phases. Then, this model was applied to a project-based learning program, conducted a perception survey on instructors and learners, and revised the metaverse instructional design model based on the results of the survey. In the Metaverse Instructional Design Model, before-lesson phase is a physical and psychological preparation stage for class participation, which includes familiarization with the Metaverse learning environment, formation of expectations for education, and self-directed pre-learning. During the lesson, to effectively deliver the lesson content, it is necessary to build confidence in the learning environment, promote learning participation, provide reference materials, perform team projects and provide feedback, digest learning content, and transfer learning content. The after-lesson phase provides strategies for ongoing interaction between learners and mentors. This study introduces a new instructional design model that utilizes metaverse and shows the potential of metaverse-based education in science and technology. It also has important implications in that it provides practical guidelines for the effective design and implementation of metaverse-based education.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.809-817
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• 2010

The primary purpose of this study was to investigate high school students' conceptual understanding of density for solids and liquids in pure and mixed substances who had preceded formal school science instruction on density and related topics. A concept assessment on density was developed and administered by demonstrative experiments accompanied by a written assessment test method to 120 general high school students in a metropolitan city. The scientific conceptions and alternative conceptions from students' responses were identified and the percentages of them were calculated. Then, their alternative conceptions and implicit theories on density were analyzed. About half of the students couldn't differentiate weight-volume-density and regarded density as an innate property of matter. Furthermore, the greater the number of variables involved in an experimental condition of the question, the more complicated and undifferentiated students' density concepts were. Students employed more improper variables such as particle size, intermolecular distance, surface tension, polarity of the solvent, etc. in explaining counter-intuitive observations. The implications for school science instruction were discussed.

• Journal of the Korean earth science society
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• v.29 no.2
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• pp.163-174
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• 2008

In this study, we compared textbook knowledge organization with students' mental models to contribute to a more well-designed instruction scheme. The selected science content was the cause of moon phases. We investigated 9 textbooks and 25 third-year middle school students. Patterns and features in participants' mental models were identified through cross inter-rater data analysis by 9 researchers, including in service teachers and experts in science education. According to the results, observing and modeling are the main activities engaged in when dealing with moon phases. The activities consisted of such concepts as: lunar revolution, the sun's parallel rays, the illuminated half of moon, and the relative positions of the sun, moon, and earth. Each concept involved inquiry skills such as: creating and manipulating models, utilizing the relationship between time and space, and communicating. However, the most important skills which are required for authentic scientific inquiry, namely controlling variables and formulating hypotheses, were missing. We categorized students' mental models into three types: scientific models, mixed models, and alternative models. The knowledge structure of each of the models was also discussed in this paper. Consequently, it was found that, typically, students were not given enough opportunities to strengthen the connection among ideas.

• Journal of the Korean earth science society
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• v.39 no.1
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• pp.103-116
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• 2018

The purpose of this study was to explore $6^{th}$ graders learning progression for lunar phase change focusing astronomical systems thinking. By analyzing the results of previous studies, we developed the constructed-response items, set up the hypothetical learning progressions, and developed the item analysis framework based on the hypothetical learning progressions. Before and after the instruction on the lunar phase change, we collected test data using the constructed-response items. The results of the assessment were used to validate the hypothetical learning progression. Through this, we were able to explore the learning progression of the earth-moon system in a bottom-up. As a result of the study, elementary students seemed to have difficulty in the transformation between the earth-based perspective and the space-based perspective. In addition, based on the elementary school students' learning progression on lunar phase change, we concluded that the concept of the lunar phase change was a bit difficult for elementary students to learn in elementary science curriculum.

• Journal of The Korean Association For Science Education
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• v.32 no.4
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• pp.703-716
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• 2012

Frequently, pre-service elementary teachers are asked to write reflective journals on their teaching during teacher education program. However, writing reflective journals can not guarantee pre-service teachers to learn from their experience. In this study, 44 reflective journals of pre-service elementary teachers on their science teaching were analyzed in terms of 'productive reflection', a concept suggested by Davis (2006). Productive reflection may help teachers' effective learning by considering interrelationships among aspects of teaching including learners and learning, subject matter knowledge, assessment, and instruction. The result showed what aspects of teaching were included, emphasized, and integrated in the pre-service elementary teachers' reflective journals. Implications for teacher education would be discussed.