• Biomolecules & Therapeutics
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• v.23 no.5
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• pp.407-413
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• 2015

Paraquat dichloride (N,N-dimethyl-4-4'-bipiridinium, PQ) is an extremely toxic chemical that is widely used in herbicides. PQ generates reactive oxygen species (ROS) and causes multiple organ failure. In particular, PQ has been reported to be an immunotoxic agrochemical compound. PQ was shown to decrease the number of macrophages in rats and suppress monocyte phagocytic activity in mice. However, the effect of PQ on macrophage cell viability remains unclear. In this study, we evaluated the cytotoxic effect of PQ on the mouse macrophage cell line, RAW264.7 and its possible mechanism of action. RAW264.7 cells were treated with PQ (0, 75, and $150{\mu}M$), and cellular apoptosis, mitochondrial membrane potential (MMP), and intracellular ROS levels were determined. Morphological changes to the cell nucleus and cellular apoptosis were also evaluated by DAPI and Annexin V staining, respectively. In this study, PQ induced apoptotic cell death by dose-dependently decreasing MMP. Additionally, PQ increased the cleaved form of caspase-3, an apoptotic marker. In conclusion, PQ induces apoptosis in RAW264.7 cells through a ROS-mediated mitochondrial pathway. Thus, our study improves our knowledge of PQ-induced toxicity, and may give us a greater understanding of how PQ affects the immune system.

• Archives of design research
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• v.15 no.1
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• pp.399-406
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• 2002

There have been diverse discourses arguing that new design has been emerging in the 21 st century. However, there have been very few trials to identify systematically the characteristics_of new design paradigm and to develop new design educational program based on them. Thus, this paper aims at development of strategy of new design educational program according to the characteristics of new design paradigm. At first, design is viewed as part of 'culture'and the structure of culture is identified: 'Artifact', 'Value', and 'Basic Assumptions'. Similarly, design is found to comprise of three fundamental attributes: 'Function', 'Aesthetics','Symbolic'. These levels are shown to be in the relation of mutually recycling influences. These structural framework is used to understand the design methods and qualification of designers over the development of design paradigms: vernacular design, machine age, and information-knowledge age. The result leads the list of requirements of new educational design program: 'Human-Centered','Situation-Based','User-Participatory', and 'Intangible'. The model of strategy of new educational design program is developed and proposed.

• Journal of Educational Research in Mathematics
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• v.17 no.4
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• pp.419-436
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• 2007

It is significant that students understand why they have to learn mathematics, because such understanding has a powerful impact not only on affective but also on cognitive aspects in mathematics education. However, studies on in what ways students perceive the purpose of mathematics education are not sufficient. Given this background, this study examined 6th grade students' conception on the intention of learning mathematics by survey and Interview in order to raise subtle but important issues to improve mathematics education. Elementary students showed that they didn't perceive the multiple purposes of mathematics education. Their conceptions were focused on practicality, academic values and the preparation for the future of mathematics. Lower achievers had a tendency to relatively more negative responses to the purposes of mathematics education. This study underlines the importance of the purpose of studying mathematics on the part of students.

• School Mathematics
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• v.10 no.3
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• pp.423-441
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• 2008

The purpose of this study was to examine the Pedagogical Content Knowledge(PCK) of teachers and their educational practice in the category of plane figure, to make a comparative analysis of their PCK and educational practice, and to discuss the relationship between their PCK and the characteristics of their instruction. Instruction of four selected elementary school teachers was analyzed to find out their educational practice. In conclusion, the characteristics of the PCK and actual instruction of the teachers could be listed as below: First, as a result of comparing their PCK and educational practice on plane figure by applying selected analysis criteria, there was a close correlation between their PCK and actual instruction. Second, the teachers had various levels of PCK on different areas. Especially, there was a large disparity in mathematical content knowledge and knowledge of teaching methods. Third, the teachers who had plenty of PCK were more excellent in textbook reconstructing, and those who fell behind in terms of PCK were more reliant on textbooks as if the textbooks had been the Bible.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.359-365
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• 2014

Oriental pear (Pyrus communis L. cv 'Niitaka') was stored at $0^{\circ}C$ for 5 months and major metabolites involved in blackening of the peel were analyzed by untargeted GC-MS and targeted HPLC methods. In this study, peels of sound and skin-blackened pears were analyzed and compared. Skin-blackened fruit was clearly characterized by a distinctive pattern in changes which included a decrease of malic acid, succinic acid, and ascorbic acid, while an increase of fumaric acid, threonine, and gluconic acid, which indicated both reduced metabolic activity and anti-oxidative capacity of the cells. Chlorogenic acid was a major phenolic compound and the peel of sound fruit showed high levels of free phenolic compounds compared than the peel of skin-blackened fruit which are believed to be related to oxidation of phenolics in skin-blackened tissue. The changes or profiling of major metabolites by targeted or untargeted analysis method could become a useful tool for understanding physiology, disorder mechanism, and identifying metabolic networks connecting primary and secondary metabolism in postharvest research.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.3
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• pp.323-345
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• 2019

This study examines the introduction of fractions in the third grade mathematics textbooks focusing on stages of units coordination and suggests alternative activities to help students develop their understanding of fractions. As results, the sessions of introduction units in textbooks was well organized to allow students to construct more extensive fraction schemes (i.e., Part-whole fraction scheme → Partitive unit fraction scheme → Partitive fraction scheme). However, most of the activities in textbooks were related to stages 1 and 2 of units coordination. In particular, the operations and partitioning schemes (i.e., equi-partitioning and splitting schemes), which are key to the development of students' fraction knowledge, were not explicitly revealed. Fraction schemes also did not extend to the Iterative fraction scheme, which is central to the construction of improper fractions. Based on these results, this study is expected to provide implications for the introduction of fractions in textbooks focusing on stages of units coordination to teachers and textbook developers.

• Journal of Science Education
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• v.34 no.1
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• pp.47-57
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• 2010

The purpose of this study was to investigate how the lesson using the newly developed Phase Change Model of Venus can change ninth graders' geocentrical concept related to the progression of the phase of Venus. In order to know students' concept change of the progression of the phases of Venus, test sheets and a questionnaire regarding solar systems were developed and used pre and post test. The results showed that many students have an astronomical preconception of geocentricism, and some students have an especially poor scientific understanding of the solar system. However, there were significant changes in students' conceptual levels (p<.05) after teaching with the Venus's Phase Change Model. Therefore, teaching with the Phase Change Model of Venus was effective on students' scientific conceptual change from geocentricism to heliocentricism.

• School Mathematics
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• v.14 no.3
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• pp.315-330
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• 2012

Mathematics educators have tried to teach mathematics to all students who are at any mathematical level by differentiated math instruction from late 1990s in Korea. The common differentiated math instruction separates students into two or three groups according to their mathematical ability and then different activities and tasks are given to each group. This kind of instruction fosters negative attitudes to mathematics to low level students and fix them at low level. So I investigated new mathematics instruction considering able students and low attainers at the same time. This new method is based on using open problems in math class. All students can respond to an open problem in different ways. If teachers could relate all varieties of answers got from students at every level to build good understanding the concept which the problem target at, low attainers could move to their potential developmental levels. This kind of instruction can change low math attainers' negative attitudes to good ones to mathematics and foster their confidence in performing mathematics.

• Journal of Embryo Transfer
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• v.33 no.2
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• pp.85-97
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• 2018

The trans-differentiation potential of mesenchymal stem cells (MSCs) is employed, but there is little understanding of the cell source-dependent trans-differentiation potential of MSCs into corneal epithelial cells. In the present study, we induced trans-differentiation of MSCs derived from umbilical cord matrix (UCM-MSCs) and from dental tissue (D-MSCs), and we comparatively evaluated the in vitro trans-differentiation properties of both MSCs into corneal epithelial-like cells. Specific cell surface markers of MSC (CD44, CD73, CD90, and CD105) were detected in both UCM-MSCs and D-MSCs, but MHCII and CD119 were significantly lower (P < 0.05) in UCM-MSCs than in D-MSCs. In UCM-MSCs, not only expression levels of Oct3/4 and Nanog but also proliferation ability were significantly higher (P < 0.05) than in D-MSCs. In vitro differentiation abilities into adipocytes and osteocytes were confirmed for both MSCs. UCM-MSCs and D-MSCs were successfully trans-differentiated into corneal epithelial cells, and expression of lineage-specific markers (Cytokeratin-3, -8, and -12) were confirmed in both MSCs using immunofluorescence staining and qRT-PCR analysis. In particular, the differentiation capacity of UCM-MSCs into corneal epithelial cells was significantly higher (P < 0.05) than that of D-MSCs. In conclusion, UCM-MSCs have higher differentiation potential into corneal epithelial-like cells and have lower expression of CD119 and MHC class II than D-MSCs, which makes them a better source for the treatment of corneal opacity.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.2
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• pp.163-184
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• 2011

The aim of this study is providing basic data to design successful in-service training program for teacher librarians by analyzing their preference on subjects of customized intensive programs for indicators of teacher expertise development. According to the survey, teacher librarians seem to regard training subjects such as Reading Education and Information Literacy Instruction related educational information services as core jobs and prefer developing instructional contents and materials. Under the levels of school it seems that teacher librarians in the elementary school are interested in programs for library activation, management of volunteers, analyses of users' needs and curricula, evaluations of user instruction and information literacy instruction. Older teacher librarians favor an understanding of metadata, building and supporting information system and instruction. Therefore, training subjects for teacher librarians should be formed by linking strategies between school library instruction and subject curricula. And in terms of the method of training, case studies and practical training might be better than lectures based on the theory.