• 한국수소및신에너지학회논문집
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• 제25권4호
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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.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.95-102
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• 2019

In order to investigate the effect of water treatment on activity of WGS catalyst, $Cu/ZnO/MgO/Al_2O_3$ (CZMA) catalysts were synthesized by co-precipitation method. The prepared catalysts were water-treated at two different temperature (250, $350^{\circ}C$). Synthesized catalysts were characterized by using BET, SEM, $N_2O$ chemisorption, XRD, $H_2-TPR$ and XPS analysis. The catalytic activity tests were carried out at a GHSV of $28,000h^{-1}$ and a temperature range of $180-320^{\circ}C$. The reduction temperature decreased with water treatment and CZMA_250 catalyst showed the lowest reduction temperature and retained a large amount of $Cu^+$. Water-treated catalysts showed increased reactivity compared to untreated catalyst and the CZMA_250 catalyst showed higher catalytic activity on WGS reaction.

• East Asian mathematical journal
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• 제37권4호
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• pp.355-379
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• 2021

In this article, we investigated plane figures introduced in elementary school mathematics in the perspective of traditional classification, and also analyzed plane figures focused on the invariance of plane figures out of traditional classification. In the view of traditional classification, how to treat trapezoids was a key argument. In the current mathematics curriculum of the elementary school mathematics, the concept of sliding, flipping, and turning are introduced as part of development activities of spatial sense, but it is rare to apply them directly to figures. For example, how are squares and rectangles different in terms of symmetry? One of the main purposes of geometry learning is the classification of figures. Thus, the activity of classifying plane figures from a symmetrical point of view has sufficiently educational significance from Klein's point of view.

• Biomolecules & Therapeutics
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• 제11권2호
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• pp.81-84
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• 2003

Recently, diabetes has been found to be associated with osteoporosis. Specially in IDDM. In both type I and type II diabetes, glucose levels are elevated. Thus, a linkage between high glucose and osteoporosis can not be ruled out. In this study, an attempt has been made to observe the effect of high glucose on bone formation; osteoblast like UMR 106 cells were treated with high glucose (22 mM, 33 mM) for 1, 3 or 7 days. The high concentration of glucose inhibited markers. of bone formation activity such as alkaline phosphatase and collagen synthesis. In addition, reduction in the level of total cellular protein in response to high glucose was also observed. This study showed high glucose concentration could alter the bone metabolism leading to a defective bone formation and thus paving the linkage of such situation to diabetic complications.

• The Korean Journal of Physiology
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• 제30권2호
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• pp.289-297
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• 1996

Excitatory amino acids (EAA) are thought to play an important role in producing cell death associated with ischemic and traumatic spinal cord injury. The present study was carried out to determine if the response characteristics of spinal sensory neurons in segments adjacent to degeneration sites induced by EAA are altered following these morphological changes. Intraspinal injections of quisqualic acid (QA) produced neuronal degeneration and spinal cavitation of gray matter. The severity of lesions was significantly attenuated by pretreatment with a non-NMDA antagonist NBQX. In extracellular single unit recordings, dorsal horn neurons in QA injected animal showed the increased mechanosensitivity, which included a shift to the left in the stimulus-response relationship, an increased background activity and an increase in the duration of after-discharge responses. Neuronal responses, especially the C-fiber response, to suprathreshold electrical stimulation of sciatic nerve also increased in most cases. These results suggest that altered functional states of neurons may be responsible for sensory abnormalities, e.g. allodynia and hyperalgesia, associated with syringomyolia and spinal cord injury.

• 농업과학연구
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• 제43권2호
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• pp.186-193
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• 2016

This study focused on the evaluation of the antioxidative effects of lotus seeds from golden colored flowers. The lotus seeds were extracted with ethanol and then fractionated into 4 fractions, ethyl acetate (EtOAc), n-butanol, methylene chloride, and n-hexane. The comparison of antioxidative activities of the extract and fractions from the lotus seeds was carried out using an in vitro radical scavenging model and the total phenol content was analyzed. Of the tested extracts and fractions, the EtOAc fraction of the lotus seeds showed the strongest 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity with 96.24% at a concentration of $100{\mu}g/mL$. In addition, the hydroxyl radical scavenging activity of the lotus seed EtOAc fraction was also increased in a concentration dependent manner with the concentrations tested ranging from 5 to $100{\mu}g/mL$. Moreover, the EtOAc fraction showed the highest scavenging activity for nitric oxide and superoxide anion radicals. In particular, of all the extracts and fractions, the EtOAc fraction showed highest contents of total phenols. These results indicate that lotus seeds have potential as an antioxidative agent against oxidative stress involving reactive oxygen species. Furthermore, the EtOAc fraction of lotus seeds includes promising oxidative stress-protective compounds.

• 생약학회지
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• 제29권1호
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• pp.22-27
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• 1998

This study was carried out to develop antitumor agents based on effects of the ethyl acetate soluble fraction of the methanolic extract of Lonicerae flos on human oral epitheloid carcinoma cells. Human oral epitheloid carcinoma cells were cultured in RPMI-1640 media containing 10% fetal bovine serum, antibiotic, and fungizone. After incubation for 24 hrs, the cells were treated with A, B, C, D, and E fractions for 48hrs under the same condition. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazoliumbromide), NR (Neutral red) and SRB (Sulforhodamine B protein) assay were performed. The light microscopic findings were observed by inverted microscope. In MTT assay, fraction B was shown significant antitumor activity (P<0.001), fraction E was shown significant antitumor activities (P<0.05), but the other fractions were not shown. In NR assay, fraction B was shown significant antitumor activity (P<0.001). In SRB assay, fractions B was shown significant antitumor activities (P<0.01). fractions A and D were shown significant antitumor activities (P<0.05). but the other fractions were not shown. In light microscopy. the fraction B of the ethyl acetate soluble fraction of the methanolic extract of Lonicerae flos showed the highest antitumor activity. These finding suggested that fraction B possessed the most antitumorous agent.

• 한국학교보건학회지
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• 제13권2호
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• pp.241-259
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• 2000

The purpose of this study is to inquire into the degree of health promotion activity of boys' high school students, and to find out the relationship between self-efficiency and health promotion behavior in order to offer basic data for developing an educational method or program for health promotion. The content validity of the instrument was authenticated by a professor of the science of nursing, and reliability is proved to be 'cronbach' a 'after mortifying content through a pre-test on 37 students. The collected 452 persons' data is analyzed in terms of average, percentage, t-test, ANOVA, Pearson' s Correlation Coefficient. and Multiple Stepwise Regression by 'SAS 6.12'. The analyzed data is the following; 1. The higher self-efficiency, among cognitive-perceptual factors, has a beneficial effect on health promotion behavior(r=.0687, p=.0001). 2. The acting degree of health promoting behavior appeares to be middled at 3.39 points out of 6. 3. The degree of self-efficiency appears at 6.04 points out of 10. 4. The difference in health promoting behavior according to a subject's general factors is the following health concern of parents (p=0.01), higher health concern of parents, makes health promoting behavior higher. 5. The difference of self-efficiency according to subject's general factors is affected by the health concerns of parents(p=0.0044) and between groups(p=0.0001).

• 한국초등과학교육학회지:초등과학교육
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• 제39권3호
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• pp.449-463
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• 2020

This study was to analysis teaching strategies, types of inquiry activities and the relationship between science concepts and inquiry activities presented in science textbooks. As a result of the study, first, the inquiry-based teaching strategies presented in science textbooks were experiment, simulation, demonstration, and field study. Second, there were 53 inquiry activities presented in 8 units related to the earth science area of science textbooks, and the types of inquiry activities were experimental observation (EO) 18, mock activity (SA) 20, investigation discussion and presentation (IP). It was analyzed as 12, data interpretation (ID) 2, and express (EX) 1 piece. Third, the relationship between inquiry activities and science concepts presented in science textbooks was analyzed. As a result of the analysis, out of a total of 42 inquiry activities, 21 inquiry activities corresponded to EA (explicit activities), in which the result of inquiry activities was directly and explicitly linked to science concepts. And IA (implicit activities), which is an implicit inquiry activity in which science concepts must be inferred using the results of inquiry activities, were analyzed as 21. In particular, IA (implicit activities), which is an implicit inquiry activity, can be said to be the result of reflecting the characteristics of earth science areas where many simulated activities (SA) are used. This is considered to be a matter to be considered in the process of developing various elementary science textbooks in the future.

• Journal of Ginseng Research
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• 제34권3호
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• pp.212-218
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• 2010

Korean red ginseng (KRG) has been shown to enhance endothelium-dependent vasorelaxation in experimental animals; however, little is known about its pharmacological effects on vascular stiffness in patients with coronary artery disease (CAD). This randomized, double-blind, placebo-controlled crossover trial was carried out to determine whether KRG has beneficial effects on arterial stiffness, cardiovascular risk factors such as plasma lipid profiles and blood pressure (BP), and Rho-associated kinase (ROCK) activity. Twenty patients (mean age, 62.5 years) with stable angina pectoris were given KRG (2.7 g/day) and a placebo alternatively for 10 weeks. Blood biochemical analysis and pulse wave velocity (PWV) recording were performed on day 0 and after the completion of each treatment. ROCK activity was assessed based on the level of phospho-$Thr^{853}$ in the myosin-binding subunit of myosin light chain phosphatase, determined by Western blot analysis of peripheral blood mononuclear cells. KRG significantly decreased the systolic BP, brachial ankle PWV, and heart femoral PWV in the patients (all p<0.05), but did not significantly alter the serum lipid profiles, including triglycerides and total, high-density lipoprotein, and low-density lipoprotein cholesterol levels. The ROCK activity tended to decrease (p=0.068) following KRG treatment. The placebo did not significantly alter any of the variables. In conclusion, KRG decreased systolic BP and arterial stiffness, probably via the inhibition of ROCK activity, in patients with CAD, but had a neutral effect on serum lipid profiles. Our data suggest that KRG has a therapeutic effect on CAD.