• Journal of The Korean Association For Science Education
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• v.31 no.5
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• pp.734-744
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• 2011

The purpose of this study was to identify middle school students' mental models on plate tectonics and to compare the mental models of verbal-learning-style students with those of visual-learning-style students. 94 student participants in 9th grade were requested to draw and explain three topics; generation of magma, the formation of the mountain range and the interior of the Earth. The criterions for analyzing the mental models are derived from the data of the drawing task. The research results were as follows: The mental models on the generation of magma were classified as 'unstable model,' 'partial casual model,' 'causal model,' and 'conceptual model.' On the other hand, the mental models on the interior of the Earth were classified as 'static unstable model,' 'dynamic unstable model,' and 'conceptual model.' Students holding 'unstable model' were unable to relate the plate collision and the magma generation. They showed a variety of alternative conceptions of study areas, such as 'magma is generated from the core' and 'the mountain is formed by rising of the plates themselves.' Also, visual-learning-style students showed higher proportion of conceptual models and lower proportion of unstable mental models than verbal-learning-style students on three topics. The findings revealed that the students tend to have different concepts on the plate tectonics depending on their learning style.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.9
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• pp.613-622
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• 2012

A chrome absorbent that is useful in rapid magnetic recovery and recycling was developed though a synthesis of Multi-Terminalized Magnetic-core Dendrimer (MTMD). Divergence through coprecipitation and rotation growth was used for synthesis. The dendrimer was multi-terminilized through methyl propionate and glutaric acid. The property analysis of the synthesized sample was performed through XRD, FT-IR, TEM, EDS, TGA and zeta potential analyzer. A magnetic-core of MTMD had a magnetite crystal and the size of 4th generation dendrimer was identified to be from 15 nm to 20 nm. Through the analysis of the TGA, the rate of the dendrimer branch for the first generation dendrimer was about 7% and 3% of diminished weight occurred as the generation grows. Also, the potential of the dendrimer when multi-terminalized, had variation from 25.26 mV to -6.53 mV. As a result of MTMD adsorption experiment, it absorbed more than 80% within 5 minutes and indicated absorptivity of 6.308 mg/g. When it was compared with COOH Dendrimer (COOH-D) after magnetic recovery, the recovery time was rapidly reduced by more than half and it could recover 100% within 30 minutes. In case of the regeneration experiment that used chrome, it was identified to maintain the same adsorptivity for four runs.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.3
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• pp.257-266
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• 2021

This study investigated the understanding of pre-service teachers in relation to the 'fog experiment' in the 5th grade 'Weather and Our Daily Life' unit of the 2009 and 2015 revised elementary school science textbooks. Pre-service teachers who participated in this study were 100 students, who are attending the university of education and taking courses in teaching research. After pre-learning about the 2009 and 2015 revised elementary school science textbooks and guide book, pre-service teachers conducted the experiment in groups. After that, the pre-service teachers individually presented answers to three questions, and the results of analyzing the answers are as follows. First, there were 24 (24%) preservice teachers who explained the difference in fog generation in the 2009 and 2015 revised curriculum with related scientific concepts such as condensation and water vapor, and only 1 (1%) of them explained the difference using the concept of saturation. Second, there were 48 (48%) pre-service teachers who found out the reason for the change in the fog experiment method according to the change in the curriculum. Third, pre-service teachers valued the reproduction and success of experiments rather than the importance of scientific knowledge, and such pre-service teachers suggested the use of alternative experiments or website.

• Korean journal of applied entomology
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• v.59 no.3
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• pp.185-202
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• 2020

The diapause induction season in Ostrinia furnacalis (Lepidoptera: Crambidae) was estimated in Suwon. Three batches of adult generations were observed, the first one from early May to early July, the second from early or mid-July to early or mid-August, and the third from mid-August to October. In outdoor larval rearing, colony rearing occurring from mid-July to mid-August produced both non-overwintering and overwintering larvae, whereas late-reared colonies produced only overwintering larvae. Larvae collected during July and August in maize fields produced both non-overwintering and overwintering larvae, whereas late-collected larvae produced only overwintering larvae. The results indicated that O. furnacalis has a bi- or trivoltine complex life cycle in this area. In the laboratory, when larvae of all instars within 9 h after molting were first treated to a diapause induction condition (11:13 h = light:dark photoperiod and 20℃), almost all larvae were induced to diapause. However, when similar treatments were conducted age-specifically for the 5th instar larvae, diapause induction rates in 3- and 4-day-old larvae of the 5th instar decreased. In contrast, when larvae were subjected to the diapause induction treatment only during the periods from the hatching stage to the 2nd, 3rd, and 4th instar, almost all larvae were not induced to diapause. The results suggest that the early age of the 5th larval instar is the last stage for sensitivity to diapause induction stimuli. In the diapause-induced larvae, hemolymph trehalose content increased and body supercooling points dropped, compared with those in non-diapause larvae.

• Journal of Sericultural and Entomological Science
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• v.34 no.1
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• pp.1-7
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• 1992

For a long-term preservation of silkworm stocks by frozen gonad storage, fundamental topics such as freezing rate and transplanting stage of the gonad, proper cryoprotectant, and super-cooling temperature and freezing point of the freezing medium were examined and following results were obtained. Proper method to anesthetize the ovary-recipient silkworm was to dip the animal to cold water for 10 minutes, and the ovary taken from the 4th instar larvae was more suitable for freezing-preservation than that from the 5th. Concerning the cryoprotectant, glycerol and DMSO were effective to prevent cryoinjury of the ovary, but sorbitol was not. The supercooling temperature and freezing point of the medium to freeze the ovary and testes were checked, and consulting with the results desirable cooling rate was confirmed. On the desirable conditions of transplanting methods, freezing rate and cryoprotectant concentration ect., the next generation was obtained when the females implanted frozen-thawed ovaries mated with normal males, but none of the normal females mated with the males implanted frozen-thawed testes laid fertilized eggs. Now it is needed to improve the connecting ration of the ducts associated with the transplanted testis to those of the hosts.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.901-907
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• 1997

The purpose of this study was to investigate the effects of green tea catechin o n free radical generation system and peroxidative damage in the liver of streptozotocin(STZ)-induced diabetic rats. Spragu-Dawley male rats weighing 150$\pm$10gm were randomly assigned to one normal and three STZ-induced diabetic groups; diabetic groups were classified to catechin free diet(DM-oC group), 0.5% catechin diet(DM-0.5C group) and 1% catechin diet(DM-1C group) according to the levels of dietary catechin supplementation. Diabetes was experimentally induced by intravenous injection of 55mg/kg of body wt of STZ in citrate buffer(pH 4.3) after feeding of three experimental diet for 4 weeks. Animals were sacrificed at the 6th day of diabetic states. Activities of serum glutamic oxaloacetic transaminase(GPT) in DM-oC groups were higher than those of the normal group, and those in catechin supplementation group were similar to those of the normal group. Liver lipid peroxide values increased by 153%, 49%, and 27% in Dm-oC, DM-0.5C and DM-0C and Dm-1C but was not significantly different in catechin supplementation groups compared with the normal group, and liver cytochrome $P_{450}$ contents was similar to result of XOD activity. In electron microscopic examination of liver, lysosome was relatively scattered in Dm-oC and Dm-0.5C group and preserved normal shapes in DM-1C group. The present results indicate that STZ-induced diabetic rats are more sensitive to oxidative stress, leading to the acceleration of lipid peroxidation process, but this was reduced by anti-oxidative effect of high level of dietary catechin. It is concluded that dietary catechin serves as powerful antioxidant against lipid peroxidation in diabetic rats.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.203-208
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• 2020

The trade war between the United States and China has been going on for many years, and sanctions against Chinese telecommunications companies in the United States are increasingly tightening. Despite these restrictions, ZTE (Zhongxing), China's leading communication equipment company, is rather expanding its market share in the global 5th generation mobile communication (5G) market. ZTE's growth and competitiveness are based on its unique corporate culture. ZTE places great importance on R&D, has a corporate culture of humility and moderation based on traditional Chinese culture. Besides, it has the placement and use of human resources in the right place. While ZTE strives to implement people-centered management, it makes good use of internal competition. Despite ZTE's global market share and corporate competitiveness, virtually nothing has been studied in Korea. The results of this study are intended to be helpful in enhancing the competitiveness of Korea's ICT industry and companies that want to expand to the world while fostering 5G.

• The Korea Journal of Herbology
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• v.31 no.5
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• pp.99-106
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• 2016

Objectives : Salvianolic acid B (SAB) is an active ingredient in Salvia miltiorrhiza frequently used for cardiovascular and cerebrovascular diseases. The present study investigated the antioxidant effects of SAB on the skeletal muscle and the brain tissue of rats following exhaustive exercise.Methods : The rats were treated with oral administration of SAB (30 mg/kg) daily for 5 days prior to the exhaustive exercise. The exhaustive exercise was performed as swimming for 150 min with 5% body weight attached to the tail on the 5th day. The antioxidant effects of SAB was evaluated by measuring the superoxide generation in the gastrocnemius and the 4-HNE expression in the hippocampal tissue. In addition, c-Fos-expressing cells in the brain tissue was observed using immunohistochemistry.Results : Histological features and muscle fiber type composition were not different between the SAB group and the exhaustive exercise group. SAB significantly reduced the upregulation of superoxide generation in the muscle tissue. SAB significantly reduced the increase of c-Fos-expressing cells in the cerebral cortex, paraventricular thalamic nucleus, dorsomedial hypothalamic nucleus, the CA1, CA3, and DG regions of hippocampus. SAB significantly reduced the upregulation of 4-HNE expression in the CA1 and DG regions of hippocampus caused by the exhaustive exercise.Conclusions : The results suggest that SAB exerts antioxidative effect against oxidative stress in the skeletal muscle and the brain tissue following exhaustive exercise, while SAB may has an anti-stress effect on stress responses in the brain.

• Journal of the Ergonomics Society of Korea
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• v.26 no.1
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• pp.87-92
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• 2007

KTX (Korea Train eXpress) is launched as the $5^{th}$ develop a ride-comfort model for high-speed rail pasengers using structural equation model (SEM). Both qualitative and quantitative factors affecting ride-comfort were investigated, and employed to construct a comprehensive ride-comfort model. The SEM model was built with twenty measurement variables and seven latent variables for the evaluation of ride-comfort of high-speed train passenger. A total of six hundreds thirty two subjects participated in the evaluation using face-to-face survey method. As a result, the proposed SEM model model fitnes (GFI=0.93). According to the results, overall ride-comfort was significantly affected by the seat-, fatigue-, interior-related, and customer satisfaction variables such as fare. Among the engineering design variables of high-speed train, seat-related variables were identified as critical factors of the ride-comfort. It is expected that the result of this study could be useful for the enhancement of ride comfort in next generation KTX.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.157-166
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• 2012

At the recent 19th General Election, Korean papers waged a surrogate war for the parties they share ideology with. All the conventional practices remained the same - the horse race-like presentations, furthering of confrontations, disregarding policy issues, allocating larger space for commentaries and negative issues, and etc. On top of these, papers began to focus on generational conflicts and individuals at the center of widespread attention and controversies, as a new trend. Photo images are largely used in the commentaries and articles dealing with confrontational or controversial situations. Of course, while the visual images seem to reinforce the emotional appeal of the messages papers try to get across, the potential problems need be noticed that could rise when irrelevant images are used.