• The Korean Journal of Ecology
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• v.28 no.5
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• pp.327-333
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• 2005

For the first time in Korea, plant size, distribution pattern and root growth form of Tamarix chinensis were surveyed at natural stand in Shiwha Lake, from June to July in 2005. T, chinensis grew in the range of 350 m towards north-south and 270 m in east-west direction. The mean number of stems germinated from same root system was 1.9. On the stem base, the numbers of living and dead plants were 1,398 and 114, respectively. Mean perimeter and height of 1,398 plants were $5.9{\pm}3.2$ cm and $159{\pm}51$ cm, respectively. By dividing into 10 classes based on the perimeter size, the largest number of plants were included in the second smallest class category. However, by dividing into 10 classes on the bases of plant height, variation in the number of plants along the height showed normal distribution curve. The heights of dead plants were small in perimeter but diverse in height. On the root base, the number of plants was the greatest in the smallest size class, and conspicuously decreased with size increment. Distribution of T. chinensis was clumped pattern. Age of the largest plant was 8-year. T. chinensis had two types of root growth. One was horizontal growth in the periphery of soil surface, and the other vertical growth.

• 대한공업교육학회지
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• v.38 no.1
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• pp.29-48
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• 2013

The purpose of this research is to provide a desirable case of STEAM education utilizing 'Energy and Transportation Technology' unit on the subject of technology home economics. The middle school students learned with the integrated approach based on STEAM integrated education, and through production process they had the opportunity for application and expression in diverse forms. The results of this process to achieve the purpose are as follows. First, as the procedural model to develop STEAM program utilizing 'Energy and Transportation Technology' unit on the subject of technology home economics, the five stages: preparation, development, verification, practice, and evaluation, were presented. The preparation stage was composed of requirement analysis, the selection of program subject, and STEAM program curriculum analysis, the selection and organization of STEAM program lesson. The development stage was composed of the development of lesson plan, multimedia teaching materials, worksheet and worksheet answer key. In the verification stage, the verification of validity by experts was conducted, and in the practice stage, the developed program was applied to the middle school students in the educational field, and in the evaluation stage, based on the evaluations received from learners and teachers, it was revised and supplemented. Second, the STEAM program was developed into the program summary map, lesson plan, multimedia teaching materials, worksheet and worksheet answer, etc., and after the validity was secured through experts' verification, it was revised and supplemented and applied to actual classes. Third, the results of the learners' evaluation of the developed STEAM program showed that the degree of satisfaction with the program was high with the average score of the entire questions being 4.00 on a five-point scale. As the teachers also evaluated the developed STEAM program as very effective, the opinions of learners and teachers were collected and the program was finally improved and completed.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.7 s.155
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• pp.1025-1033
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• 2006

Kenaf bast can be obtained by decortication of Kenaf stem. Kenaf fibers are much more rough than cotton fiber because they include impurities as pectin, lignin and hemicellulose besides cellulose. The purpose of this research is to investigate the distribution of kenaf fiber length and diameter during the processes of removing impurities. To remove pectin, kenaf bast was retted chemically. A half of the retted kenaf fiber bundle were scoured and bleached. The other half one were treated with $NaClO_2$ solution to remove lignin, and were treated with sodium hydroxide solution to remove hemicellulose. Four kinds of specimens that were obtained for investigating physical characteristics. Length and diameter of 100 fibers on each specimen was measured. The tensile strength of 100 fiber bundles were measured. And also the color values of them were measured with spectrocolorimeter. The length of retted kenaf fiber was 16.97cm. Then it decreased to 11.43cm after bleaching. Kenaf fiber bundles could be finer by chemical processes that remove non-cellulosic materials. The thickness of retted fiber was $132{\mu}m$. And after undergoing the chemical processes to remove non-cellulosic materials, the thickness of kenaf fiber became finer as $73{\mu}m$. Tensile strength of the retted kenaf fiber bundles was 11.37Mpa. The retted kenaf fiber lost their strength as 22.6% by bleaching and as 18.3% by treatment for removing lignin. The retted kenaf fiber showed low whiteness as 56.48 of L*value. After bleaching, the kenaf fibers have creamy white color and their whiteness got 90.02 of L*value. After the treatment for removing hemicellulose, the kenaf fibers also have creamy white color and their whiteness got L* value of 79.02.

• Journal of The Korean Association For Science Education
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• v.34 no.4
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• pp.335-347
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• 2014

Size/scale is a central idea in the science curriculum, providing explanations for various phenomena. However, few studies have been conducted to explore student understanding of this concept and to suggest instructional approaches in scientific contexts. In contrast, there have been more studies in mathematics, regarding the use of number lines to relate the nature of numbers to operation and representation of magnitude. In order to better understand variations in student conceptions of size/scale in scientific contexts and explain learning difficulties including alternative conceptions, this study suggests an approach that links mathematics with the analysis of student conceptions of size/scale, i.e. the analysis of mathematical structure and reasoning for a number line. In addition, data ranging from high school to college students facilitate the interpretation of conceptual complexity in terms of mathematical development of a number line. In this sense, findings from this study better explain the following by mathematical reasoning: (1) varied student conceptions, (2) key aspects of each conception, and (3) potential cognitive dimensions interpreting the size/scale concepts. Results of this study help us to understand the troublesomeness of learning size/scale and provide a direction for developing curriculum and instruction for better understanding.

• Journal of Korean Classical Literature and Education
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• no.37
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• pp.47-73
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• 2018

This thesis aims to find out the purpose of recording . I tried to understand the reason that the compiler of included this song in the record of King Yuri. The result of tracking the intention of the compiler in this thesis is as follows. I think that was chosen as a symbol of King Yuri's character, especially connected with his inner side. By introducing a hobby that contained the inner side of King Yuri, the compiler implied that his failures and mistakes in subsequent governments stem from human limitations that did not adequately refine his qualities. I think that the compiler who showed the character of King Yuri through only one short song also showed the highest level of enjoying poetry. The enjoyment of literature is a pleasure in understanding the life of someone through literature and bring it back into their lives. In this respect, by pursuing the intend of the compiler, we will be close to the value of the song, .

• Journal of The Korean Association For Science Education
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• v.39 no.3
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• pp.321-335
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• 2019

This study aims to explore the influencing factors and the process of enhancing science self-efficacy (SSE) and to lay the foundation in understanding science self-efficacy of students. The ten categories related to the science self-efficacy were derived through the coding of the interview data based on the grounded theory and paradigm analysis to develop a process model of science self-efficacy improvement. Through the process analysis, four cyclical phases were found in the process of enhancing SSE: 'Entering into learning science' phase, 'enhancing SSE' phase, 'adjustment' phase, and 'result' phase. More specifically, the phase of 'entering into learning science' is where students choose science track and stimulated to construct SSE. The phase of 'enhancing SSE' is where students taking a science track actively learn science and perform science activities. In the phase of 'adjustment', students come to have successful performance about learning science and performing science activities by using diverse strategies. Finally, 'result' phase indicates different appearances of students depending on SSE levels. The phases were non-linear and periodically repeat depending on situation. The core category in the selective coding was indicated to be 'enhancing science self-efficacy.' Students' SSE form by learning science and performing science activities. These finding may help better understand the behavior of students who are taking a science track by facilitating effective science learning through the increase of their SSE levels.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.212-220
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• 2022

When it comes to single node leafy stem cuttings of rose (Rosa hybrida), environmental management such as air temperature, relative humidity, and light affect productivity. In order to investigate the effect of air temperature and relative humidity on the cutting success rate and rooted cuttings quality, a transparent airtight box was used to implement a closed system. We have also tried to find out the most effective photoperiod and the number of leaflets in closed system using artificial light (white LED, 104.0 µmol·m^-2·s^-1 photosynthetic photon flux density). The first experiment was conducted for a total of 6 weeks under 4 airtight period conditions. The number of roots and longest root length decreased as the airtight period increased. But there were no significant differences in the survival rate, shooting rate, and rooting rate according to airtight periods. In the second experiment the results indicated that survival and shooting rate were significantly affected by the photoperiod (0/24, 2/22, 4/20, 8/16, and 16/8 h), the number of leaflets (0, 2, and 4 leaflets) of the cuttings and their interaction. The survival rate was the highest in the 16-h day length and 4 leaflets. By considering survival rate and shooting rate with energy efficiency, the 8-h day length and 2 or 4 leaflets were judged to be the most effective.

• Journal of The Korean Association For Science Education
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• v.36 no.5
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• pp.757-768
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• 2016

This study developed an SSI (Socio-Scientific Issue) discussion program that applies a creative technique called six thinking hats, and then investigated the differences in argumentation patterns and effects on the decision-making abilities of each character feature of students between SNS debate and existing face to face debate. There were three SSI themes - Designer Babies, embryonic stem cell study, and legitimacy of abortion. Students were divided into two groups, the debate group using SNS and face to face debate group. The character patterns of students were divided to 'extraversion,' 'agreeableness,' and 'conscientiousness' through test sheets for character features for each student. Both groups were educated for creative discussion methods using six thinking hats and then, the class progressed. As a result of analyzing argumentation patterns used in SNS debate and face to face debate, the most used argumentation pattern was the "cause pattern." But comparing to face to face debate, other patterns (mark, inference, authority, motive) were also used in SNS debate. The study analyzed three factors of decision-making ability for each character feature of students such as complexity, perspectives, and inquiry. As a result, for 'complexity' factor, there was a significant difference between SNS debate group and face to face debate group only in the student group of Agreeableness. For 'perspectives' factor, there were significant differences between SNS debate group and face to face debate group in all three characters. Finally, for inquiry, there were no significant differences between SNS debate group and face to face debate group in all three characters. Accordingly it would be necessary to apply SNS debate using the six thinking hats in SSI education to enhance perspectives.

• Journal of The Korean Association For Science Education
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• v.35 no.1
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• pp.53-64
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• 2015

This research was performed of high school science classes. These science classes progressed by using Scratch, and surveyed students' perception after finishing each class. This research was conducted of male students who want to choose department of natural science in the next grade. Those classes are consisted of four classes. This study produced a journal, and contained expressions of their thinking and feeling based on experiences during attending classes and projects. Consequently, that journal was analyzed in view of understanding and perception of Scratch using science classes, and it was also included of utilizing Scratch program. Research shows following three conclusions. First, students preferred Scratch using class to general one. They attend more active with high interest, and they felt senses of accomplishment while they make output by themselves. Second, their studies passed through three stages. These are problem perception, problem solving, and producing. Problem solving stage is especially complicated and difficult stage to students. This stage is consisted of Scratch side and Science side. Scratch side has Design and applying process, and Science side has data gathering and analyzing. Students' comprehension of scientific knowledge is increased and is preserved long time through this stage. Last, students had a hard time using Scratch. Because, it is the first time to them to use that program. Therefore, we deemed that they needed to start this kind of experience at lower grade than they are now, such as middle school stage. It is expected that this type of classes are getting more expanded and more populated as a part of students' core ability.

• Journal of Life Science
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• v.29 no.6
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• pp.724-734
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• 2019

The present study investigated the cytotoxicity of particulate matter (PM) derived from car air filter (outdoor PM) and home cleaner filter (indoor PM) in the various human cell lines. Each outdoor and indoor PM were harvested by ethanol extraction method, subsequently sieved with 10 um filter paper, sterilized with autoclave and added to culture media. The half maximal inhibitory concentration ($IC_{50}$) values was significantly (p<0.05) lower in the outdoor PM, compared with indoor PM, and the significantly (p<0.05) higher $IC_{50}$ values were observed in the cancer cell lines (A-549 lung adenocarcinoma and AGS stomach adenocarcinoma), than those of normal MRC-5 fibroblasts and dental papilla tissue derived-mesenchymal stem cells (DSC). After being exposed to $100{\mu}g/ml$ outdoor PM for 7 days, the population doubling time (PDT) was significantly (p<0.05) increased in especially MRC-5 and DSC cell lines, compared with untreated cell lines. Further, the expression of senescence-associated ${\beta}$-galactosidase activity was up-regulated in all the cells exposed to outdoor PM than those of untreated control. Besides, the expression level of inflammation-associated genes, such as cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6) was found to be significantly (p<0.05) increased in the outdoor PM-treated cell lines than those of untreated cell lines. Our results showed that PM induces the cytotoxicity via arrest of cell growth, cell damage and inflammation response.