• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.25-31
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• 2009

This study was carried out to investigate the mutagenic, antimutagenic, cytotoxicity and antitumor effects of Adenophora triphylla (AT). AT was extracted with 70% ethanol and then further fractionated to hexane, chloroform, ethyl acetate, butanol and water. Antimutagenic, cytotoxicity and antitumor effects of AT extracts were measured by using Ames test, SRB method, and the tumor growth inhibition test. AT extracts did not show any mutagenicity in the Ames test; however, 70% ethanol extracts and its fractions had strong antimutagenic effects against mutation induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 4-nitroquinoline-1-oxide (4NQO). The ethyl acetate fraction of AT (200 ${\mu}g$/plate) showed approximately 66.5% inhibitory effect on the mutagenesis induced by 4NQO against TA98 strain, whereas 83.3% and 75.1% inhibitions were observed on the mutagenesis induced by MNNG and 4NQO against TA100 strain. In anticancer effects, the cytotoxicity of AT extract and its fractions against cancer cell lines including human cervical adenocarcinoma (HeLa), human hepatocellular carcinoma (Hep3B), human breast adenocarcinoma (MCF-7), human gastric carcinoma (AGS), human lung carcinoma (A549) and transformed primary human embryo kidney (293) were investigated. The treatment of 1 mg/mL AT ethyl acetate faction had the highest cytotoxicity of 79.9%, 74.9%, 66.0%, 71.0% and 74.3% against HeLa, Hep3B, MCF-7, AGS and A549 cells, respectively. In contrast, the extract and its fractions showed only $3{\sim}36%$ cytotoxicity for a normal human kidney cell line (293). In vivo anti-cancer effect of Adenophora triphylla extract was tested using Balb/c mice transplanted sarcoma-180 cells. Adenophora triphylla ethyl acetate fraction showed the highest inhibition rate of 37.2% at the 50 mg/kg concentration.

• Journal of the Korean Society of Combustion
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• v.19 no.2
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• pp.21-27
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• 2014

Experimental study in laminar propane coflow jet flames has been conducted to investigate self-excitations. For various propane mole fractions and jet velocities, two types of self-excitation were observed: (1) buoyancydriven self-excitation (hereafter called BDSE) and (2) Lewis-number-induced self-excitation coupled with (1) (hereafter called LCB). The mechanism of Lewis-number-induced self-excitation (hereafter called LISE) is proposed. When the system $Damk\ddot{o}hler$ number was lowered, LISE was shown to be launched. The LISE is closely related to heat loss, such that it can be launched in even helium-diluted methane coflow-jet flame (Lewis number less than unity). Particularly, The LISE becomes significant as the $Damk\ddot{o}hler$ number decreases and heat-loss is excessively large.

• Journal of Powder Materials
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• v.26 no.3
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• pp.214-219
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• 2019

In this study, the microstructure and characterization of an overlay welding layer using Fe-based composite powders are reported. The effects of the number of passes and composition of powders on the microstructure and mechanical properties are investigated in detail. The welding wire and powders are deposited twice on a stainless-steel rod using a laser overlay welding process. The microstructure and structural characterization are performed by scanning electron microscopy and X-ray diffraction. The mechanical properties of the first and second overlay layers are analyzed through the micro-Vickers-hardness tester and abrasion wear tester. In the second overlay layer, the hardness and specific wear are approximately 840 Hv and $2.0{\times}10^{-5}mm^3/Nm$, respectively. It is suggested that the increase of the volume fractions of $(Cr,Fe)_7C_3$ and NbC phases in the second welding layer enhances the hardness and wear resistance.

• Journal of Korean Society on Water Environment
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• v.30 no.1
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• pp.80-86
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• 2014

Unlike to natural organic matters (NOMs), effluent organic matters (EfOMs) are not well understood due to their complexity and heterogeneity. In this study, EfOMs from sewage and industrial wastewater treatment effluents and Suwannee River NOM (SRNOM) were isolated into hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions. Specific ultraviolet absorbance (SUVA) and fluorescence excitation emission matrix (FEEM) analyses were used to characterize physicochemical properties. In addition, acute toxicity and oxidative stress to Daphnia magna were evaluated to characterize toxicological properties. EfOMs showed similar properties to microbially derived organic matters having low hydrophobicity, which are totally different from SRNOM having high hydrophobicity. Moreover, acute toxicity and antioxidant enzyme activity in D. magna was largely dependent on fraction types of EfOMs. These findings suggest that EfOMs have different physicochemical and toxicological properties compared with those of NOMs, which needs to be further identified with various sources of EfOMs.

• The Plant Pathology Journal
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• v.38 no.2
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• pp.115-130
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• 2022

Though information exists regarding the pathogenesis of the shot-hole disease (SH) in flowering cherry (FC), there has been a lack of research focusing on SH management. Therefore, here, we investigated the inhibitory activities of antagonistic bacteria against SH pathogens both in vitro and in vivo as well as their biochemical characteristics and bioactive compounds. Two biosurfactant-producing bacterial antagonists, identified as Bacillus velezensis strains JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal SH pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains also strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, solvent extracts, and biosurfactants of the two strains exhibited antimicrobial activities. Liquid chromatography/electrospray ionization time-of-flight mass spectrometric analysis of the partially purified active fractions revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of FC leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by Epicoccum tobaicum and Bukholderia contaminans, respectively. In addition, the two antagonists produced indole-3-acetic acid, siderophore, and a series of hydrolytic enzymes, along with the formation of a substantial biofilm. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the SH pathogens and their efficiency in the biocontrol of SH.

• Archives of Pharmacal Research
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• v.21 no.3
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• pp.223-230
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• 1998

The effect of an ethanolic extract of the plant Trianthema portulacastrum L. on the $CCI_4$-induced chronic hepatocellular damage of Swiss albino mice has been investigated. The normal mice received olive oil (0.2 ml/mouse) for five weeks. The $CCI_4$ control mice, on the other hand, received $CCI_4$ (0.05 ml/mouse) in olive oil for five weeks. The extract was administered at the dose of 100 mg/kg or 150 mg/kg for five weeks by gastric intubation in addition to $CCI_4$ treatment. The $CCI_4$ administraction alone caused hepatocellular necrosis, severe anemia, leucopaenia, lymphocytopaenia, neutrophilia, eosinophilia and haemoglobinaemia along with the alterations of plasma albumin and globulin. The administration of plant extract (at 100 or 150 mg/kg) restored the $CCI_4$-induced alterations of the haematological parameters to the normal level. The extract of T. portulacastrum elicited a marked protection against $CCI_4$-induced hepatotoxicity as indicated by the several haematological parameters, related indices of formed elements, and different fractions of plasma protein. We also observed the dose-dependent antihepatotoxic effect of the extraction on these mice. The 150 mg/kg of extract was found to be more effective in normalizing the toxic effects of $CCI_4$ on the above parameters of mice. These results suggest that the hepatoprotective effect of T. poltulacastrum could be caused by its critical involvement in modulating several factors associated with erythropoiesis, and the boosting of general immunity of the host.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.430-434
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• 2014

$SiC_f$/SiC composites were prepared using the hybrid process of chemical vapor infiltration (CVI) and polymer impregnation and pyrolysis (PIP). Before the application of PIP, partially matrix-filled preform composites with different densities were fabricated by control of chemical vapor infiltration time and temperature. The changes of the final density of the $SiC_f$/SiC composites had a tendency similar to that of preform composites partially filled by CVI. Composites with lower density after the CVI process had a larger increment of density during the PIP process. Three types of microstructures were observed on the fractured surface of the composite: 1) well pulled-out fibers and lower density, 2) slightly pulled-out fibers and higher density, and 3) only bulk SiC. The different fractions and distributions of the microstructures could have an effect on the mechanical properties of the composites. In this study, $SiC_f$/SiC composites prepared using a hybrid process of CVI and PIP had density values in the range of $1.05{\sim}1.44g/cm^3$, tensile strength values in the range of 76.4 ~ 130.7 MPa, and fracture toughness values in the range of $11.2{\sim}13.5MPa{\cdot}m^{1/2}$.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.237-245
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• 2013

Canthaxanthin (cx) is a potent antioxidant that is chemically synthesized at the industrial scale and has imperative applications in the cosmetic and feed industries. An orange pigmented mesophilic bacterium, designated as K44, was isolated from soil samples of Kargil, India. Biochemical tests, 16S rRNA gene sequencing, and FAME analysis of the bacterium indicated it to belong in the genus Dietzia and is distinct from human isolates. The strain showed 98% 16S rRNA gene sequence homology with Dietzia maris DSM 43102. High-performance liquid chromatography profile of the pigments isolated from K44 showed two major peaks absorbing at 465.3 and 475 nm. The liquid chromatography-mass spectrometry (LC-MS) analysis of both these peaks revealed their m/z to be 564. The molecular weights, LC-MS/MS fragmentation patterns, and ${\lambda}_{max}$ of these fractions corresponded to all-trans- (475 nm) and 9-cis-(465.3 nm) cx isomers. The antioxidant activities of cis- and trans-cx isomers isolated from this bacterium were found to differ, where the cis-isomer showed higher free radical, superoxide radical, and reactive oxygen species scavenging activities than the alltrans- isomer, suggesting that 9-cis-cx is more effective as an antioxidant than the all-trans-cx.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.450-455
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• 1998

Pine has been known as a traditional medicinal plant and as showing a physically beneficial function to a human being. Therefore, this study was performed to investigate the physiological activities of main pine neddles. Ethanol extracts from pinus needles did net exhibit any mutagenicity. On the contrary, inhibitory effects of ethanol extract were observed on mutagenicity induced by N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), 4-nitroquinoline-1-oxide (4NQO), 3-amino-1,4-dimethyl-5H-pyrido-(4,3-b)indol (Trp-P-1) and benzo(a)pyrene $(B({\alpha})P)$ using Salmonella typhimurium reversion assay. On direct-acting mutagen (MNNG, 4NQO) and indirect-acting mutagen (Trp-P-1, $(B({\alpha})P)$, we observed higher inhibitory effect. Stepwise fractionation of the ethanol extract was done by using ether, chloroform, ethyl acetate, butanol and water to obtain effective fraction. Among them, water fractions $(100\;{\mu}g/plate)$ of Pinus thunbergii, Pinus rigida, Pinus densiflora and Pinus koraiensis showed high inhibition of 91.65%, 94.7%, 84.22% and 79.02%, respectively, on the mutagenicity of MNNG in Salmonella typhimurium TA100.

• Education of Primary School Mathematics
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• v.27 no.3
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• pp.281-301
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• 2024

Many students have experienced difficulties due to the discontinuity in instruction between arithmetic and algebra, and in the field of elementary education, algebra is often treated somewhat implicitly. However, algebra must be learned as algebraic thinking in accordance with the developmental stage at the elementary level through the expansion of numerical systems, principles, and thinking. In this study, algebraic thinking-based classes were developed and conducted for 6th graders in elementary school, and the effect on the ability to solve word-problems in fraction division was analyzed. During the 11 instructional sessions, the students generalized the solution by exploring the relationship between the dividend and the divisor, and further explored generalized representations applicable to all cases. The results of the study confirmed that algebraic thinking-based classes have positive effects on their ability to solve fractional division word-problems. In the problem-solving process, algebraic thinking elements such as symbolization, generalization, reasoning, and justification appeared, with students discovering various mathematical ideas and structures, and using them to solve problems Based on the research results, we induced some implications for early algebraic guidance in elementary school mathematics.