• Elastomers and Composites
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• v.57 no.4
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• pp.188-196
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• 2022

Styrene-butadiene rubber(SBR) is a copolymer of styrene and butadiene. It is composed of 1,2-unit, 1,4-unit, and styrene, and its properties are dependent on its microstructure. In general, rubber composites contain a single rubber or a blended rubber. Similarly, SBR is used by mixing with natural rubber(NR) and butadiene rubber(BR). The composition of a rubber article affects its physical and chemical properties. Herein, an analytical method for determining the microstructure of SBR using via pyrolysis is introduced. Pyrolysis-gas chromatography/mass spectrometry is widely used to analyze the microstructure of polymeric materials. The microstructure of SBR can be determined by analyzing the principal pyrolysis products formed from SBR, such as 4-vinylcyclohexene, styrene, 2-phenylpropene, 3-phenylcyclopentene, and 4-phenylcyclohexene. An analytical method for determining the composition of SBR/NR, SBR/BR, and SBR/NR/BR blends via pyrolysis is introduced. The composition of blended rubber can be determined by analyzing the principal pyrolysis products formed from each rubber component.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.343-348
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• 2019

In this paper, a dual-band antenna is proposed for the autonomous vehicle as well as omni-directional. The proposed antenna operates in the 4G/LTE band (1,710~2,170MHz) and 5G/NR band (3,400~3,700MHz). In order to obtain the dual-band operation, the planar monopole antenna is proposed as the novel structure with single port of the 50ohm. To give the properties of dual-band, an additional antenna element with slit was added to the planar monopole antenna, and then a structural adjustment parameter was optimized for achieving the target performance in bands. The planar monopole antenna in the LTE band acts as the coupled feed for the added parasitic radiator in the 5G NR band. The proposed antenna has $38.5{\times}36.0{\times}1.0[mm^3]$ on a ground with diameter of 96mm. From the fabrication and measurement results, the impedance bandwidth (VSWR<2) of the proposed antenna covers 1,480~2,260MHz (LTE band: 1,710~2,170MHz) and 3,310~3,930MHz (5G NR band: 3,400~3,700MHz). The proposed planar monopole antenna also obtained the measured gain and radiation pattern of omni-directional radiation pattern in the anechoic chamber.

• BMB Reports
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• v.41 no.3
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• pp.242-247
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• 2008

MSS, a comprising mixture of maesil (Prunus mume Sieb. et Zucc) concentrate, disodium succinate and Span80 (3.6 : 4.6 : 1 ratio) showed a significant improvement of memory when daily administered (460 mg/kg day, p.o.) into the normal rats for 3 weeks. During the spatial learning of 4 days in Morris water maze test, both working memory and short-term working memory index were significantly increased when compared to untreated controls. We investigated a molecular signal transduction mechanism of MSS on the behaviors of spatial learning and memory. MSS treatment increased hippocampal mRNA levels of NR2B and TrkB without changes of NR1, NR2A, ERK1, ERK2 and CREB. However, the protein levels of pERK/ERK and pCREB/CREB were all significantly increased to $1.5{\pm}0.17$ times. These results suggest that the improving effect of spatial memory for MSS is linked to MAPK/ERK signaling pathway that ends up in the phosphorylation of CREB through TrkB and/or NR2B of NMDA receptor.

• Elastomers and Composites
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• v.35 no.4
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• pp.261-271
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• 2000

Physical properties of NR vulcanizates cured by both sulfur and resole were studied. Cure characteristics of the compounds were also investigated. Two types of resoles with different molecular weight distributions were employed. The scorch time of the NR compound containing the resole with a low molecular weight distribution was shorter than that of the compound containing the resole with a high one. Crosslink densities of the NR vulcanizates with a high resole content after the thermal aging at $95^{\circ}C$ decreased, while that of the vulcanizate without resole after the thermal aging at $95^{\circ}C$ increased. Though crosslink densities of the NR vulcanizates with a high resole content decreased with increasing the aging time, the moduli increased while the tensile strength and tear strength decreased.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.5
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• pp.468-475
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• 1992

In order to understand more clearly the integration between N-assmilation and C-metabolism in relation to N fertilization, a pot experiment with 5 different level of N fertilization(0, 5, 10, 25, 50 mM NO$_3$$_{[-10]}$ ) was conducted in Manchester, U.K. The peas (Pisum sativum L., cv. Early Onward) were sown in vermiculate (5 cm depth) and cultivated for 6 days under temperature controlled dark room conditions ($25^{\circ}C$). The plants received frequent irrigation with a nutrient solution: it was fertilized every 2 days, 3 times a day at 10h, 13h, 16h respectively. Elevated NO$_3$$^{[-10]}$ concentration, the activity levels of NR, NiR, total GS(crude extract), GS$_2$(plastid) in both root and shoot were increased and reached the peak in 5～25 mM, except NiR specific activity which increased its activity continually until 50 mM NO$_3$$^{[-10]}$ treatment. Total activities of GS (crude extract) in both root and shoot became higher than those of GS$_2$(Plastid), and the activity ratios of total GS in the crude extract and GS$_2$ in the plastids were 3.0 to 4.3 in root, but 3.2 to 10.6 in shoot. It was concluded that the reductants and A TP from OPPP itself should be enough to achieve the high rate of NR, NiR, GS$_1$, GS$_2$ in plant root and shoot for reduction or assimilation of nitrogen, but these enzyme activities might be inhibited by an excess of NO$_3$$^{[-10]}$ influx over the reduction capacity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.19 no.1
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• pp.20-30
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• 1993

Liquid Chromatographic behavior of Pd(II) in Isonitosoethylacetoacetate imine IEAA-NR: R=H, CH3, C2H5, n-C3H7, n-C4H9, C6H5-CH2) Chelates were investigated by reversed phase high performance 1iquid chromatography on Micropak MCH-5 Column using Methanol /water as mobile phase. The optimum condition for the separation of Pd-Isonitrosoethylacetoacetate imine chelates were examined with respect to the flow rate, mobile phase strength. It was found that Pd(IEAA-NR)2 chelates were eluted in an acceptable range of the capacity factor value (0 $\leq$ log k' $\leq$ 1), The dependence of the logarithm of capacity factor(k') on the volume fraction of water in mixture with in the binary mobile phase was examined. Also, the dependence of k'on the liquid-liquid extraction distribution constant in methanol-water / n-alkane extraction system was on system was invert tigated for Pd(IEAA-NR)2. Both kinds of dependence are linear, which suggests that the retention of the electroneutral metal chelates be largely due to the solvophobic effect.

• Elastomers and Composites
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• v.4 no.1
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• pp.83-88
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• 1969

As a part of a series of previous studies, physical properties of various portions of a tire made of NR-Syn. R bloods were studied. 1. It was found, in general, most effective for tire tread when 50 parts of HAF black was blended with NR and Syn. R with a ratio of 70/30. 2. It was found that the use of SBR 1712 has an advantage in price, easy processing and physical properties than other synthetic rubber. 3. A technical compounding of various portions of a tire has to be determined for optimum cure conditions.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1605-1610
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• 2017

The electrochemical luminescence (ECL) device was investigated, which has similar structure to the dye-sensitized solar cell. The structure of the ECL cell in this experiment reliably induces a large amount of the oxidation around electrodes. The band gap of the ECL electrode is of 3.0 - 3.2 eV. Titanium dioxide ($TiO_2$) nanoparticle has following properties: a band gap of 3.4 eV, a low-priced material, and 002 preferred orientation (Z-axis). Zinc Oxide (ZnO) nanorod is easy to grow in a vertical direction. In this paper, in order to determine material suitable for the ECL device, the properties of various materials for electrodes of ECL devices such as ZnO nanorod (ZnO-NR) and $TiO_2$ nanoparticle ($TiO_2-NP$) were compared. The threshold voltage of the light emission of the ZnO-NR was 2.0 V which is lower than 2.5 V of $TiO_2-NP$. In the other hand, the luminance of $TiO_2-NP$ was $44.66cd/m^2$ and was higher than that of $34cd/m^2$ of ZnO-NR at the same applied voltage of 4 V. Based on the experimental results, we could conclude that $TiO_2-NP$ is a more suitable electrode material in ECL device than the ZnO-NR.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.453-456
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• 2001

The purpose of this research was to investigate the effects of extracts from cultured hairy roots of R. undulatum on human kidney epithelial cells. Hairy roots were induced by a co-culture with A. rhizogenes ATCCl5834 and cultured in WPM medium. The cytotoxicity was measured by colorimetric assay using 3-(4,5-dimethythiazol-2-yl)-2,5- diphenyl-2H -tetrazolium bromide (MTT), neutral red (NR) and sulforhodamine protein B (SRB) with human kidney epithelial cell lines A498. MTT, NR and SRB quantities decreased propotionally in cultured A498 cells treated with the water or chloroform extracts of cultured hairy roots at increasing concentrations. These results suggest that extracts of cultured hairy 개ots are cytotoxic on human epithelial cells. The cytotoxicity of chloroforrm fraction was stronger than that of water fraction. The values of $MTT_{50}$, $NR_{50}$, $SRB_{50}$ of the extracts of chloroform fraction and those of water fraction were measured to be 289.3${\mu}g$/ml, 302.7${\mu}g$/ml. 433.8${\mu}g$/ml and 475.8${\mu}g$/ml. 428.3${\mu}g$/ml, 549.5${\mu}g$/ml in A498 cell line.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.691-697
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• 1996

The NR films were prepared with mixing of natural rubber latex(NRL) with various additives, and NR/CR films were prepared by blend ratio of chloroprene rubber latex(CRL). The swelling degree and the mechanical properties of these films were measured according to the procure time. As a result, optimum condition were showed the swelling degree : 80~85%, precure time : 48~60hrs., and tensile strength was reduced but elongation was increased as increasing the blend ratio of CRL. On the mechanical properties of films prepared by different dipping process in these optimum condition, the tensile strength and tear strength of NR/CR films by one dipping process are better than NR-d-CR films by two dipping process. The surface of these films were observed with scanning electron microscopy(SEM). It was found that phase separation was occured as increasing the blend ratio of CRL.