• East Asian mathematical journal
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• v.24 no.5
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• pp.431-464
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• 2008

In this paper, we investigate reduction and four rules of fractional calculation on GuJangSulHae and the other Sanhakseo, and elementary school mathematics education.

• Archives of Plastic Surgery
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• v.42 no.5
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• pp.588-595
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• 2015

Background Radiotherapy treatment after keloidectomy is known to be an effective method for reducing the rate of recurrence. However, to date, the appropriate total radiation dose and fractionation have not yet been confirmed. The authors performed a retrospective analysis to identify the appropriate radiation dose and fractionation in post-keloidectomy radiotherapy. Methods From May 2000 to February 2011, postoperative radiotherapy was performed on 39 lesions in 28 patients after total keloidectomy. The keloid lesions were confined to the ear lobes. Between May 2000 and May 2004, 14 keloids were treated with surgical excision, followed by a total radiation dose of 1,200 cGy in three fractions over four to five days (group 1). Between June 2004 to February 2011, 25 keloids were treated with surgical excision, followed by a total radiation dose of 1,500 cGy in three fractions over four to five days (group 2). Patients were given a survey asking them to report their experiences regarding reoperation, recurrence of symptoms, recurrence of the lesion, and satisfaction with the operation. Results Of the 28 patients who were treated, 20 underwent follow-up. Group 2 had more cases showing elevation with erythematous changes, whereas group 1 had more cases showing progressive stages of elevation than group 2. These differences were statistically significant. Moreover, a correlation was observed between the level of keloid elevation and the extent of symptoms. Conclusions We suggest 1,500 cGy of radiation in three fractions following keloidectomy for ear lobe keloids. A further randomized study is needed to assess the recurrence of keloids after radiotherapy.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.249-257
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• 2020

This study investigated whether the extracts from cosmos flowers exhibit antibacterial activities and identified which components were ascribed to the antibacterial effects. The antibacterial effects of extracts from white, pink, and violet cosmos flowers were observed for 24 h after inoculation with four kinds of bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. Among the three fractions of cosmos flower extracts, the best antibacterial activity against the four bacteria was observed in the extracts isolated from the EtOAc layer. However, the extracts from the CHCl₃ layer were also effective against S. aureus. Moreover, the first of white, second of pink, and first of violet silica gel fractions (Fr.) isolated from the EtOAc layer exhibited minimal inhibition at a concentration of 0.1 mg/mL. Comparison of NMR and High-Pressure Liquid Chromatography results between silica gel Fr. and apigenin suggested that the effective fractions can contain a component including apigenin moiety.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.357-363
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• 2020

Oxidative stress caused by the overproduction of reactive oxygen species (ROS) is known as an etiology of neurodegenerative diseases. Populus tomentiglandulosa (PT), a member of the Salicaceae family, is widely grown in Korea and has been reported to exert protective effects on cerebral ischemia by attenuating of oxidative stress and neuronal damage. In the present study, we investigated the antioxidant activity and neuroprotective effects of an ethanol extract and four fractions [n-butanol, ethyl acetate (EtOAc), chloroform, and n-hexane] of PT under in vitro and cellular systems. The extract and four fractions of PT showed 1,1-diphenyl-2-picrylhydrazyl (DPPH), •OH, and O2- radical scavenging activities in a dose-dependent manner. In particular, the EtOAc fraction of PT had the strongest DPPH, •OH, and O2- radical scavenging activities among the extract and other fractions. Therefore, we further investigated the neuroprotective effect of the EtOAc fraction of PT against oxidative stress in H2O2-induced SH-SY5Y cells. Treatment with H2O2 significantly decreased cell viability and lactate dehydrogenase (LDH) release, and it also increased the ROS levels compared to the normal group. However, treatment with the EtOAc fraction of PT significantly increased cell viability. Moreover, the EtOAc fraction of PT-treated group significantly suppressed ROS production and LDH release compared to the H2O2-induced control group. In conclusion, our findings indicated that PT had in vitro antioxidant activity and neuroprotective effects against oxidative stress. Therefore, PT could be used as a natural agent for protection against oxidative stress.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1169-1173
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• 2006

Extracted fractions of the green seaweed Ulva lactuca were studied to verify the cytotoxicity and immunostimulating activity. The fractions from the ethanol extract of U. lactuca were prepared by the systematic extraction procedure with solvents such as hexane, ethyl ether, methanol, butanol and $H_2O$. The cytotoxic effects of U. lactuca fractions against human leukemia cell line U937, mouse neuroblastoma cell line (NB41A3), human hepatoma cell line (HepG2) and rat glioma cell line (C6) were investigated. Ethyl ether fraction showed the highest cytotoxicity against all four cell lines tested. In addition, $H_2O$ fraction also showed relatively high cytotoxicity. Dose dependent patterns were observed on all four cell lines. The immune-stimulating effects of U. lactuca fractions on rat macrophage cell line (RAW 264.7) were also investigated. All five fractions of U. lactuca extract stimulated NO production with concentration dependant manner. These results suggest that U. lactuca may be a useful candidate for a natural cancer preventing and immune-stimulating agents.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1666-1673
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• 2011

The presence of sialoglycoproteins (SGPs) in the membranes from goat (Capra aegagrus hircus), buffalo (Bubalus bubalis bubalis) and pig (Sus scrofa domestica) erythrocytes was investigated by partial purification with a chloroform-methanol extraction method followed by Sodium dodecyl sulphate - Polyacrylamide gel electrophoresis in comparison to human (Homo sapiens) erythrocytes. The results show that mammalian erythrocytes possess clear differences in the SGPs numbers and molecular weights although all animals studied in this experiment are from the same class i.e. mammalia. The SGPs number in human, goat, buffalo and pig are four (PAS-1 to PAS-4), ten (PAS-GI to PAS-GX), seven (PAS-BI to PAS-BVII) and four (PAS-PI to PAS-IV) respectively as indicated by staining the polyacrylamide gel with sialoglycoprotein-specific Periodic acid-Schiff's (PAS) stain. The new SGPs could be observed only after the partial purification of membrane fractions named as PAS-HI with molecular weight (Mr) 190 kDa and PAS-HII 150 kDa in human, PAS-BIA in buffalo and PAS-PIA and PAS-PIVA in pig. The gels were also stained with Coomassie brilliant blue (CBB) and Silver stain to check the contamination of other membrane proteins in the purified fractions. The quantitative distribution of SGPs was also determined by densitometry. Present study indicates that there are some basic differences in mammalian erythrocyte membrane SGPs, especially with respect to their number and molecular weights indicating major structural variations.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.4
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• pp.309-316
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• 2001

Helianthus tuberosus has been known to inhibit the growth of weeds and other plants sharing its habitat. This study was conducted to identify the allelochemicals of Helianthus tuberosus which were extracted with water and solvents. Aqueous extracts of leaf, stem, root, tuber and tuber peel of Helianthus tuberosus except tuber did not show significant differences in phytotoxicity to alfalfa seedlings. It was considered that Helianthus tuberosus contained fewer or less potential water-soluble substances that were toxic to alfalfa. Methanol extract of leaves of Helianthus tuberosus was sequentially partitioned in increasing polarity with n-hexane, ethylacetate and n-butanol. Each extract had a yield of 148, 12, 15.7 and 9.5g, respectively. Inhibitory effects on germination of alfalfa seeds treated with four fractions were not significantly different. But the significant reductions on hypocotyl length were observed for all the solvent extracts. Among the four fractions, the ethylacetate fraction showed the most significant inhibition effect on bioassay with alfalfa. Further separation of the active ethylacetate fraction by open column chromatography led to the 25 subfractions. In bioassay of each sub-fraction with alfalfa seeds, sub-fraction No. 13 showed the most inhibitory effect on seedling growth. $^1$H NMR and gas chromatography-mass spectrometry analysis revealed that sub-fraction No. 13 was the mixture of straight-chain saturated fatty acids.

• School Mathematics
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• v.15 no.3
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• pp.569-583
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• 2013

In Korea, the school mathematics curricula have been revised in every average 6 years by the government. From the year 2013, the new revised curricula called 2009 version are implied. The subject of elementary mathematics in this new curricula contains four issues to be improved. First, it should be allowed to call the basic figures such as box, cylinder, ball, quadrilateral, triangle and circle in verbal languages. Second, the name of the activities to define mathematical concepts should be changed from 'Yaksok', which means 'promise' in English, to a better and more honest one. Third, the concave polygons should be treated together with the convex ones. Fourth, the calculations of fractions should be weakened as much as possible for the elementary school children.

• Journal of Gifted/Talented Education
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• v.24 no.1
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• pp.17-43
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• 2014

On the subjects of elementary 3rd grade three child prodigies who had learned the four fundamental arithmetic operations and primary concepts of fraction, this study conducted a qualitative case research to examine how they composed schema of addition and multiplication of fractions and transformed schema through recognition of precise concepts and linking of concepts with addition and multiplication of fractions as the contents. That is to say, this study investigates what schema and transformed schema child prodigies form through composition of primary mathematic concepts to succeed in relational understanding of addition and multiplication of fractions, how they use their own formed schema and transformed schema for themselves to approach solutions to problems with addition and multiplication of fractions, and how the subjects' concept formation and schema in their problem solving competence proceed to carry out transformations. As a result, we can tell that precise recognition of primary concepts, schema, and transformed schema work as crucial factors when addition of fractions is associated with multiplication of fractions, and then that the schema and transformed schema that result from the connection among primary mathematic concepts and the precise recognition of the primary concepts play more important roles than any other factors in creative problem solving with respect to addition and multiplication of fractions.

• Journal of Nutrition and Health
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• v.31 no.7
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• pp.1093-1099
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• 1998

Dioscorea japonica Thunb its effects has been used in f31k remedies f9r various purposes including treatment of diabetes, on hypoglycemic actiity and energy metabolism were investigated. The plant was extracted with methanol(MeOH) and fractionated into four layers hexane, chloroform(CHCI$_3$), butanol(BuOH), and $H_2O$. Diabetes mellitus was induced in male Sprague-Dawley rats by the injection of streptozotocin(STZ) into tail vein at a dose of 45mg/kg body weight(BW). Sprague-Dawley male rats weighing 160-200g were divided into five groups a diabetic control and four experimental groups such as hexane group, CHCl$_3$ group, BuOH group, and $H_2O$ group. The rats of all groups were fed on a AIN-76 diet and the four experimental groups were orally administered each fraction(500mg/kg BW) for 12 days. The diabetic control group was orally administered 5% carboxymethyl cellulose. The body weights were monitored and the concentrations of blood glucose were determined. The levels of glycogen and protein in liver were also measured. The plasma levels of cholesterol, triglyceride (TG), and fee fatty acid(FFA) were also analysed. The body weight gain was higher in the $H_2O$ group than in the control group. Heart weight was significantly reduced by administrations of Dioscorea japonica Thunb. The extents of blood glucose decrement in BuOH and $H_2O$ group were greater than that found in the control group. The muscle protein levels showed significantly higher amounts in all experimental groups. Glycogen levels were higher in the BuOH group than in the control group. The levels of TG were decreased in all experimental groups and the levels of plasma FFA were lower in the BuOH group. The plasma cholesterol levels were not influenced by these four fractions in diabetic rats. These results suggest that the orally administered H2O fraction of Dioscorea japonica Thunb exhibited hypoglycemic effects in STZ induced diabetic rats. (Korean J Nutrition 31(7) : 1093-1099, 1998)