• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.319-325
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• 2018

The use of 3D printing (Additive Manufacturing) technology has expanded from initial model production to the mass production of parts in the industrial field based on the continuous research and development of materials and process technology. As a representative polymer material for 3D printing, the polyamide-based material, which is one of the high-strength engineering plastics, is used mainly for manufacturing parts for automobiles because of its light weight and durability. In this study, the specimens were fabricated using Selective Laser Sintering, which has excellent mechanical properties, and the flexural characteristics were analyzed according to the temperature of the two types of polyamide 12 and glass bead reinforced PA12 materials. The test specimens were prepared in the directions of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ based on the work platform, and then subjected to a flexural test in three test temperature environments of $-25^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. As a result, PA12 had the maximum flexural strength in the direction of $90^{\circ}$ at $-25^{\circ}C$ and $0^{\circ}$ at $25^{\circ}C$ and $60^{\circ}C$. The glass bead-reinforced PA12 exhibited maximum flexural strength values at all test temperatures in the $0^{\circ}$ fabrication direction. The tendency of the flexural strength changes of the two materials was different due to the influence of the plane direction of the lamination layer depending on the type of stress generated in the bending test.

• Journal of Astronomy and Space Sciences
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• v.19 no.1
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• pp.7-18
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• 2002

Interstellar cabon monoxide and its isotopes were observed with the 13.7m radio telescope of the Daeduk Radio Astronomy Observatory toward Orion Molecular Cloud-1 (OMC-1). We derive the excitation temperature, optical depth, column density, and isotopic abundance ratios from the observed lines of $^{12}CO,^{13}CO,\;and\;C^{18}O$ inside of the region of $11'{\times}11'$. The optical depths of $^{13}CO$ were obtained to be 0.1~0.4, while those of $C^{18}O$ to be 0.01~0.03. The isotopic ratios $^{12}C/^{13}C$ were also estimated to be 2~60. We could not find the radial isotopic ratio $^{12}C/^{13}C$ gradient in the OMC-1.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.543-550
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• 2011

Conductive SiC-$ZrB_2$ composites were produced by subjecting a 40:60 (vol%) mixture of zirconium diboride (ZrB2) powder and ${\beta}$-silicon carbide (SiC) matrix to spark plasma sintering (SPS). Sintering was carried out for 5 min in an argon atmosphere at a uniaxial pressure and temperature of 50 MPa and $1500^{\circ}C$, respectively. The composite sintered at a heating speed of $25^{\circ}C$/min and an on/off pulse sequence of 12:2 was denoted as SZ12L. Composites SZ12H, SZ48H, and SZ10H were obtained by sintering at a heating speed of $100^{\circ}C$/min and at on/off pulse sequences of 12:2, 48:8, and 10:9, respectively. The physical, electrical, and mechanical properties of the SiC-$ZrB_2$ composites were examined and thermal image analysis of the composites was performed. The apparent porosities of SZ12L, SZ12H, SZ48H, and SZ10H were 13.35%, 0.60%, 12.28%, and 9.75%, respectively. At room temperature, SZ12L had the lowest flexural strength (286.90 MPa), whereas SZ12H had the highest flexural strength (1011.34 MPa). Between room temperature and $500^{\circ}C$, the SiC-$ZrB_2$ composites had a positive temperature coefficient of resistance (PTCR) and linear V-I characteristics. SZ12H had the lowest PTCR and highest electrical resistivity among all the composites. The optimum SPS conditions for the production of energy-friendly SiC-$ZrB_2$ composites are as follows: 1) an argon atmosphere, 2) a constant pressure of 50 MPa throughout the sintering process, 3) an on/off pulse sequence of 12:2 (pulse duration: 2.78 ms), and 4) a final sintering temperature of $1500^{\circ}C$ at a speed of $100^{\circ}C$/min and sintering for 5 min at $1500^{\circ}C$.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.699-704
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• 2007

This experiment was conducted to investigate growth and flowering characteristics of Iris koreana and Iris minutoaurea Makino native to Korea for potting plant of early spring treated by forcing date and temperature. As forcing date delayed from November 1 to December 1, the plant height and number of leaves were increased, however no difference in the number of flower and date of flowering. In Iris koreana, the plant was not flowering in forcing on November 1, flowering 30% on November and 100% on December 1. However all the forcing plant flowered in Iris minutoaurea Makino. As forcing temperature increased from $7^{\circ}C$ to $15^{\circ}C$, the plant height and number of leaves were decreased, however the number of flower in $7^{\circ}C$ was increased and date of flowering was earlier than ones of higher temperature. In Iris koreana, the plant was not flowered in forcing $12^{\circ}C$ and $15^{\circ}C$, all flowered in forcing $7^{\circ}C$. Iris minutoaurea Makino was flowered 30% forcing in $12^{\circ}C$ and all flowered forcing in $7^{\circ}C$.

• Journal of Microbiology
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• v.35 no.1
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• pp.53-60
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• 1997

Pseudomonas sp. P20 and Pseudomonas sp. DJ-12 isolated from the polluted environment are capable of degrading biphenyl and 4-chlorobiphenyl (4CB) to produce benzoic acid and 4-chlorobenzoic acid (4CBA) respectively, by pcbABCD-encoded enzymes. 4CBA can be further degraded by Pseudomonas sp. DJ-12, but not by Pseudomonas sp P20. However, the meta-cleavage activities of 2, 3-dihydroxybiphenyl (2, 3-DHBP) and 4-chloro-2, 3-DHBP dioxygenases (2, 3-DHBD) encoded by pcbC in Pseudomonas sp. P20 were stronger than Pseudomonas sp. DJ-12. In this study, the pcbC gene encoding 2, 3-DHBD was cloned from the genomic DNA of Pseudomonas sp. P20 by using pKT230. A hybrid plasmid pKK1 was constructed and E. coli KK1 transformant was selected by transforming the pKK1 hybrid plasmid carrying pcbC into E. coli XL1-Blue. By transferring the pKK1 plasmide of E. coli KK1 into Pseudomonas sp. DJ-12 by conjugation, a recombinant strain Pseudomonas sp. P20, Pseudomonas sp. DJ-12, and the recombinant cell assay methods. Pseudomonas sp. DJ12-C readily degraded 4CB and 2, 3-DHBP to produce 2-hydroxy-6-oxo-6-phenylhexa-2, 4-dienoic acid (HOPDA), and the resulting 4CBA and benzoic acid were continuously catabolized. Pseudomonas sp. DJ12-C degraded 1 mM 4CB completely after incubation for 20 h, but Pseudomonas sp. P20 and Pseudomonas sp. DJ-12 showed only 90% and Pseudomonas sp. DJ-12 had, but its degradation activity to 2, 3-DHBP, 3-methylcatechol, and catechol was improved.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.5
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• pp.447-453
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• 2013

Osteoblastic activity of nectandrin A was examined in C2C12 cells. Nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization, manifested by the up-regulation of differentiation markers (alkaline phosphatase and osteogenic genes) and increased calcium contents. In C2C12 cells co-transfected with expression vector encoding Smad4 and Id1-Luc reporter, nectandrin A increased Id1 luciferase activity in a concentration-dependent manner, when compared to that in BMP-2 treated cells, indicating that Smad signaling pathway is associated with nectandrin A-enhanced osteoblastic differentiation in C2C12 cells. In addition, nectandrin A activated p38 mitogen-activated protein kinase (MAPK) in time- and concentration-dependent manners, and phosphorylated form of pSmad1/5/8 and alkaline phosphatase activity were both decreased when the cells were pretreated with SB203580, a p38 MAPK inhibitor, suggesting that p38 MAPK might be an upstream kinase for Smad signaling pathway. Taken together, nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization of C2C12 cells via activation of p38 MAPK-Smad signaling pathway, and it has a therapeutic potential for osteoporosis by promoting bone formation.

• Plant Biotechnology Reports
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• v.3 no.1
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• pp.75-85
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• 2009

We report here a first evaluation of chilling-responsive gene regulation in the sweetpotato. The growth of sweetpotato plants was severely retarded at $12^{\circ}C$; the lengths of the leaf, petiole, and root were markedly reduced and microscopic observation revealed that the elongation growth of the epidermal cells in each of these organs was significantly reduced. We examined the transcriptional regulation of three sweetpotato expansin genes (IbEXP1, IbEXP2 and IbEXPL1) in response to various chilling temperatures (12, 16, 22, and $28^{\circ}C$). In the leaf and petiole, the highest transcript levels were those of IbEXP1 at $28^{\circ}C$, whereas IbEXPL1 transcript levels were highest in the root. IbEXP1 mRNA levels in the $12^{\circ}C-treated$ petiole showed a fluctuating pattern (transient decrease-recovery-stable decrease) for 48 h. In the leaf and petiole, IbEXP1 and IbEXPL1 exhibited a similar response to chilling in that their mRNA levels decreased at $22^{\circ}C$, increased at $16^{\circ}C$, and decreased dramatically at $12^{\circ}C$. In contrast, mRNA levels of IbEXP2 in the leaf fell gradually as the temperature fell from 28 to $12^{\circ}C$, while they remained unaltered in the petiole. In the root, mRNA levels of IbEXPL1 and IbEXP1 reached maximum levels at $16^{\circ}C$, and decreased significantly at $12^{\circ}C$. These data demonstrated that expression of these three expansin genes was ultimately down-regulated at $12^{\circ}C$; however, transcriptional regulation of each expansin gene exhibited its own distinctive pattern in response to various chilling temperatures.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.261-267
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• 1982

The objective of this study was to test germinability of sesame (Sesamum indicum L.) varieties at low temperatures. Seeds of III sesame varieties representing different maturity groups and countries were tested at four different temperatures between $10^{\circ}C$ and $16^{\circ}C$. Average germination percentages of III varieties were 92%, 57% and 3.3% at $16^{\circ}C, 14{\circ}C$ and $12^{\circ}C$.respectively. The highest daily germination percentage was observed after 4 days of incubation at $16^{\circ}C$, while it was after 8 days at $14^{\circ}C$. A regression analysis indicated that $15^{\circ}C$ as the minimum temperature for satisfactory germination in field conditions. In general, Korean local collections had better germinability than introduced varieties from 6 countries at different latitudes. 'San dong', a Korean local cultivar. showed the highest germination percentage (24%) at $12^{\circ}C$ when the average germination percentage of all varieties was as low as $3.3^{\circ}C$. Early maturity varieties germinated better at $12^{\circ}C$ and $14^{\circ}C$ than medium or late maturity groups, but no difference was observed at $16^{\circ}C$. Although larger seeds showed better germinability within a variety, there seems to be no relationship between seed size and germinability in sesame.in sesame.

• The Korean Journal of Mycology
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• v.15 no.1
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• pp.9-13
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• 1987

The qualitative and quantitative analysis of fatty acids in the Korean White Poria cocos(Schw.) Wolf were performed. Dry powder of sample was extracted with chloroform-methanol(2 : 1, v/v) mixed solvent. The extract was saponified and methylated, and then analyzed by gas chromatography. Total 24 peaks were observed in the gas chromatogrom and 5 peaks i.e, $C_{8:0}\:;\:caprylic\:acid$, $C_{11:0}\:;\:undecanoic\:acid$, $C_{12:0}\:;\:lauric\:acid$. $C_{12:1}\:;\:dodecenoic\:acid$ and $C_{16:0}\:;\:palmitic\:acid$ were identified. Major components were $C_{8:0}\:and\:C_{12:1}$ were determined as $6.657\:{\mu}g/g\:and\:10.176{\mu}g/g$ respectively.

• BMB Reports
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• v.46 no.3
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• pp.169-174
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• 2013

The human $B_{12}$ trafficking chaperone hCblC is well conserved in mammals and non-mammalian eukaryotes. However, the C-terminal ~40 amino acids of hCblC vary significantly and are predicted to be deleted by alternative splicing of the encoding gene. In this study, we examined the thermostability of the bovine CblC truncated at the C-terminal variable region (t-bCblC) and its regulation by glutathione. t-bCblC is highly thermolabile ($T_m={\sim}42^{\circ}C$) similar to the full-length protein (f-bCblC). However, t-bCblC is stabilized to a greater extent than f-bCblC by binding of reduced glutathione (GSH) with increased sensitivity to GSH. In addition, binding of oxidized glutathione (GSSG) destabilizes t-bCblC to a greater extent and with increased sensitivity as compared to f-bCblC. These results indicate that t-bCblC is a more sensitive form to be regulated by glutathione than the full-length form of the protein.