• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.108-114
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• 2015

The purpose of this study is to find the relationships among communication competency, social network centrality(trust centrality and knowledge sharing centrality), discussion performance, and online boarding activity in the team based learning situation. For investigating this topic, 44 students are participated in the classes of educational technology. In order to find out the relationships among communication competency, social network centrality, discussion performance, and online boarding activity, compared t-test and path analysis are used. Followings are the results of the research: (a) Communication competency is improved significantly after team based learning. (b) Trust centrality effects significantly on the knowledge sharing centrality. (c) Knowledge sharing effects significantly on discussion performance. (d) Trust centrality effects on the online boarding activity in the team based learning.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.299-300
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• 2012

We investigate the relation between star formation activity and PAH $3.3{\mu}m$ emission. Our targets are mid-infrared-excess galaxies selected from the AKARI all-sky survey point source catalog. We performed AKARI near-infrared spectroscopy for them. As a result, we obtained $2.5-5{\mu}m$spectra of 79 galaxies, and selected 35 star-forming galaxies out of them. Comparing the PAH $3.3{\mu}m$ luminosities with the infrared luminosities, we find a linear correlation between them. However, by adding the results from literatures for luminous infrared galaxies and ultra-luminous infrared galaxies that are more luminous than our sample, the ratio of the PAH to the infrared luminosity is found to decrease towards the luminous end.

• Journal of Photoscience
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• v.9 no.2
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• pp.21-24
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• 2002

Pineal organs of poikilotherm vertebrates transform the environmental light information into a humoral message and a neuronal activity. The former is melatonin, and the latter is modulation of the impulse in ganglion cells. The ganglion cells are physiologically classified into luminosity (achromatic) type and chromatic one, as the neural activity is modulated in two ways. We attempted to classify the pineal ganglion cells with morphological characteristics by means of the three- dimensional reconstruction method. In the pineal ganglion cells of river lamprey, there are two different features, oval and spherical. For comparison of their projection region in the brain, the tracing investigation was also carried out. The application of the neural tracer near mesencephalic tegmentum showed that only oval-shaped ganglion cells were labeled in the pineal organ. These results suggest that the oval-shaped ganglion cell is functionally different from the spherical one.

• Journal of Korean Elementary Science Education
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• v.32 no.1
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• pp.22-35
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• 2013

In this study, we analyzed the problems of grade 3~4 science textbooks developed for the 2007 revised national curriculum raised by elementary school teachers. 53 elementary school teachers were selected and asked to complete the open questionnaire to find out the problems they experienced or perceived when they taught the corresponding unit of the science textbooks. The responses were coded and categorized through researchers' cross analysis. The result revealed various problems in using the science textbooks in real classroom context. The problems were divided into three dimensions as inquiry activity aspect, science knowledge aspect, and science learning assessment aspect. Each dimension consisted of several categories. We explained the frequency and representative examples of the problems in each category. These can provide some guidelines and implications for new science textbook developers and science education policy makers.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.513-518
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• 2009

This study was carried out to investigate the changes of yield, total phenolics, saponin content and composition, antimicrobial, and antioxidant activities of various fractions of fine ginseng root (Panax ginseng C.A. Mayer) by maceration method in the order of increasing polarity (hexane, chloroform, ethyl acetate, butanol, and water). Butanol fraction showed the highest total saponin content compare to other fractions. Hexane fraction could harvest significantly high ginsenoside Rg2, Rg1, and Rf (p<0.05). And the contents of ginsenoside Rh1, Rg3, and Rg1 showed relatively higher in the fraction of ethyl acetate than other fractions. The system of hexane-chloroform-ethyl aceate-butanol showed relatively high content of ginsenoside Re, Rd, Rc, Rb3, and Rb1. However, the last fraction of water still remained lots of Rb2 content. The fraction of water was the highest phenolics. The 1,1-diphenyl-2-picryhydrazil, superoxide, and hydroxyl radical scavenging activity of water fraction was higher than the other fractions. In antimicrobial activity, the fraction of hexane showed relatively high antimicrobial activity against Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, Bacillus cereus, and Escherichia coli. And the fractions of the chloroform and ethyl acetate showed higher antimicrobial activities than the other samples in against P. aeruginosa and S. typhimurium.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.356-360
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• 2005

Xanthine dehydrogenase (XDH), a classic enzyme involved in purine catabolism, can catalyze the formation of redox-signaling reactive oxygen and nitrogen species such as superoxide and nitric oxide. We generated transgenic plants of Arabidopsis in which XDH was knocked out by introduction of hairpin RNA-expression vector. Expression analysis by reverse transcription-PCR and in-gel staining of XDH activity revealed that transgenic lines efficiently suppressedXDH expression at the transcriptional level, demonstrating that RNA interference was successfully induced. XDH-suppressed transgenic lines exhibitedincreased biomass production during the growth of seedlings.

• Journal of The Korean Association For Science Education
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• v.11 no.2
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• pp.13-21
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• 1991

For development of teaching model for observational experiment and the major contents of science education guide books published for secondary school teacher in America, the actual survey to the secondary schools and the investigation of science education guide were carried out. The results were summarized as follows. 1. The major concepts of contents in science education books are constituted of introduction(9.67%), ability(8.94%), activity(6.61%), curriculum(11.61%), instruction planning(5.25%), instruction strategy(l7.74%), materials and facilities(1O.97%), evaluation(8.62%), society and community(l0.55%), guidelines(4.76%), practice(3.54%), and index(1.74%). 2. The constitution of multimedia teaching model for observational instruction was developed and arranged in order of six steps as observation, materialization, broad understanding, advanced study, application, and synthesis. This model was thought as the most effective for the achievement of the instructive goal for observational unit and others.

• Korean Journal of Medicinal Crop Science
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• v.15 no.1
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• pp.56-61
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• 2007

This study was carried out to determine the antioxidant activity and vitamin C contents in plant extracts of the Momordica charantia L. The vitamin C was detected as the highest content in immature fruit (92.2 mg/100 g), while the content in stem (2.5 mg/100 g) was lower 40 times than that of immature fruit. Antioxidant activity for the dried sample was investigated by TBA method. The lowest TBARS values were obtained from extracts of dried leaf and followed by ascorbic acid and BHT, showing that the extracts from dried leaf possess the strongest antioxidant activity. Compared with fresh tissues, SOD activity, ATX activity and CAT activity were high level in the dried tissue. These results suggest that the Momordica charantia L. would be a promising antioxidant source as an alternative antioxidant, based on natural plant resources.

• Journal of The Korean Association For Science Education
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• v.32 no.6
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• pp.1063-1071
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• 2012

The purpose of this study is to investigate the relation between the classification ability quotient and cortisol-hormonal change of middle school students. Thirty-three students, second graders in middle school, performed the classification task that can be an indicator of students' classification ability. And then amount of the secreted hormone was analyzed during task performance. The study results were as follows: First, the classification methods of students mostly utilized visual, qualitative. Their classification patterns for each subject were static, partial, and non-comparative. Second, the amount of stress-hormone was secreted from students during the experiment decreased in overall after the free classification. It seemed that student-centered activity relieved stress. Third, the classification ability quotient turned out to be significantly correlated to the stress hormone, which means that there was a close relationship between classification ability and stress level. It was also considered that stress had a positive effect on the improvement of classification ability. This study provided physiologically more accurate information on the stress increased in the learning process than other conventional studies based on reports or interviews. Finally, researchers could recognize the effect of stress in the cognitive activity and the need to find an appropriate level of stress in learning processes.

• Journal of Hydrogen and New Energy
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• v.25 no.4
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.