• The Korean Journal of Food And Nutrition
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• v.34 no.5
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• pp.537-544
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• 2021

In this study, antioxidative activities of Jeolpyun containing Smilacis chinae R. extract powder (2%, 4%, 6%, 8%) were evaluated using total polyphenol contents, electron donating ability on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and decomposing ability of hydrogen peroxide. In chromaticity analysis, the brightness significantly decreased with increasing Smilacis chinae R. extract powder content. Jeolpyun containing 6% Smilacis chinae R. extract powder revealed the highest value (9.67±0.603) for the redness and 2% Smilacis chinae R. extract powder was the highest value (14.20±0.917) for the yellowness. Total polyphenol contents of Jeolpyun containing 8% Smilacis chinae R. extract powder were the highest content of 17,320±390.38 ㎍ gallic acid equivalent/mL (GAE/mL). Total polyphenol contents were significant relation at p<0.05. Electron donating ability for Jeolpyun containing 8% Smilacis chinae R. extract powder revealed the highest electron donating ability (74.24±0.827%). Electron donating abilities revealed significant difference (p<0.05). Jeolpyun containing 6% Smilacis chinae R. extract powder revealed the most hydrogen peroxide decomposing ability (-3.38±1.44) and hydrogen peroxide decomposing ability revealed significant difference (p<0.05).

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.464-469
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• 2021

A reforming catalyst for hydrogen production from ammonia is being studied. Non-novel metal based Ni catalysts for use in ammonia reforming processes are being developed. In this study, the ammonia reforming characteristics according to Ni content of the alumina pellet supported catalyst in the mid-temperature region were investigated under different space velocity. 20 Ni and 3,000 h^-1 showed the best catalytic activity with ammonia conversion of 63% among all conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.185-194
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• 2024

Fe-Ni nanocatalysts loaded on carbon black were prepared via spontaneous reduction reaction of iron (II) acetylacetonate and nickel (II) acetylacetonate in dry process. Their morphology and elemental analysis were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analyzer. The loading weight of the nanocatalysts was measured by thermogravimetric analyze and the surface area was measured by BET analysis. TEM observation showed that Fe and Ni nanoparticles was well dispersed on the carbon black and their average particle size was 4.82 nm. The loading weight of Fe-Ni nanocatalysts on the carbon black was 6.83-7.32 wt%, and the value increased with increasing iron (II) acetylacetonate content. As the Fe-Ni loading weight increased, the specific surface area decreased significantly by more than 50%, because Fe-Ni nanoparticles block the micropores of carbon black. I-V characteristics showed that water electrolysis performance increased with increasing Ni nanocatalyst content.

• BMB Reports
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• v.38 no.2
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• pp.218-224
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• 2005

Antioxidant enzymes are related to the resistance to various abiotic stresses including salinity. Barley is relatively tolerant to saline stress among crop plants, but little information is available on barley antioxidant enzymes under salinity stress. We investigated temporal and spatial responses of activities and isoform profiles of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), non-specific peroxidase (POX), and glutathione reductase (GR) to saline stress in barley seedlings treated with 200 mM NaCl for 0, 1, 2, 5 days, respectively. In the control plant, hydrogen peroxide content was about 2-fold higher in the root than in the shoot. Under saline stress, hydrogen peroxide content was decreased drastically by 70% at 2 d after NaCl treatment (DAT) in the root. In the leaf, however, the content was remained unchanged by 2 DAT and increased about 14 % at 5 DAT. In general, the activities of antioxidant enzymes were increased in the root and shoot under saline stress. But the increase was more significant and consistent in the root. The activities of SOD, CAT, APX, POX, and GR were increased significantly in the root within 1 DAT, and various elevated levels were maintained by 5 DAT. Among the antioxidant enzymes, CAT activity was increased the most drastically. The significant increase in the activities of SOD, CAT, APX, POX, and GR in the NaCl-stressed barley root was highly correlated with the increased expression of the constitutive isoforms as well as the induced ones. The hydrogen peroxide content in the root was most highly correlated with the CAT activity, indicating an increased role of CAT in hydrogen peroxide detoxification under salinity stress. In addition, the results suggest the significance of temporal and spatial regulation of each antioxidant isoform in determining the competence of the antioxidant capacity under saline stress.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1532-1535
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• 1996

Diamond-like carbon (DLC) films have been prepared by a widely-used plasma CVD with an rf (13.56MHz) plasma of $CH_4$ gas. The hydrogen incorporated in DLC films plays an important role of determining the film properties, but its exact role has not been clear. In this study, the effect of hydrogen on the film properties of DLC has been examined by adding the hydrogen gas to the $CH_4$ gas during deposition and by exposing the prepared film to the hydrogen plasma. As the content of additive hydrogen gas increases, the density and hardness of the film increase, but the growth rate decreases. The FT-IR spectroscopy results show that the number of C-H bonds decreases with increasing the hydrogen gas. Also, the variation in the position of "G" and "D" peaks due to additive hydrogen, which has been measured by the Raman spectroscopy, indicates of $sp^3$ fraction.

• Korean Journal of Materials Research
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• v.12 no.4
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• pp.235-239
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• 2002

In this study mesh-type PECVD system was suggested to minimize the hydrogen concentration. The main structural difference between the triode system and a conventional system is that, a third electrode, a mesh, is inserted between the powered and the ground electrode. We investigated several conditions to compare with conventional PECVD. The main effect of mesh was to minimize the substrate damage by ion bombardment and to enhance the surface reaction to induce hydrogen desorption. It was also found that hydrogen concentration decreased but deposition rate increased as increasing applied bias. Applied DC-bia s enhanced sputtering process. Intense ion bombardment causes the weakly bonded hydrogen or hydrogen-containing species to leave the growing film and increased adatom mobility. Furthermore, addition of hydrogen gas enhance the surface diffusion of adatom.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.772-779
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• 2011

New type of syngas generator based on the partial oxidation of biogas in volumetric permeable matrix reformers was suggested as an effective, adaptable and relatively simple way of syngas and hydrogen production for various low-scale applications. The use of biogas as an energy source reduces the chance of possible emission of two greenhouse gases, $CH_4$ and $CO_2$, into the atmosphere at the same time. Its nature of being a reproducible energy source makes its use even more attractive. Parametric screening studies were achieved as air ratio, biogas component ratio, input gas temperature, Steam/Carbon ratio. As the air ratio was low, the production of the hydrogen and carbon monoxide increased in the condition that 3D matrix reformer maintains the stable driving. As it was the simulation biogas in which the carbon dioxide content is high, the flammable range became narrow. And the flammable range was extended if the injected gas was preheated. The stable driving was possible in the low air ratio. The amount of hydrogen production was increased as S/C ratio increased.

• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.315-319
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• 2010

In this study, the hydrogen reduction behavior of ball-milled NiO nanopowder was investigated depending on the partial pressure of water vapor. The hydrogen reduction behavior was analyzed by thermogravimetry and hygrometry under heating to 873 K in hydrogen. In order to change the partial pressure of the water vapor, the dew point of hydrogen was controlled in the range of 248 K~293 K by passing high-purity hydrogen through a saturator that contained water. Interestingly, with the increase in the dew point of the hydrogen atmosphere, the first step of the hydrogen reduction process decreased and the second step gradually increased. After the first step, a pore volume analysis revealed that the pore size distribution in the condition with a higher water vapor pressure shifted to a larger size, whereas the opposite appearedat a lower pressure. Thus, it was found that the decrease in the pore volume during the chemical reaction controlled process at a dew point of 248 K caused a reduction in retardation in the diffusion controlled process.

• Corrosion Science and Technology
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• v.6 no.4
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• pp.164-169
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• 2007

Hydrogen induced cracking (HIC) was studied phenomenologically and the effect of microstructure on HIC was discussed for the steels having two different levels of nonmetallic inclusions. Steels having different microstructures were produced by thermomechanically controlled processes (TMCP) from two different heats which had the different level of nonmetallic inclusions. Ferrite/pearlite (F/P), ferrite/acicular ferrite (F/AF), ferrite/bainite (F/B) were three representative microstructures for all tested steels. For the steels with higher level of inclusions, permissible inclusion level for HIC not to develop was different according to steelmicrostructure. On the contrary, HIC occurred also at the martensite/austenite (M/A) constituents regardless of steel microstructure when they accumulated to a certain degree. It was proved that M/A constituents were easily embrittled by hydrogen atoms. Steels having F/AF is resistant to HIC at a given actual service condition since they covers a wide range of diffusible hydrogen content without developing HIC.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.147-148
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• 2014

This article describes an investigation of flame stability characteristics with various compositions of synthetic natural gas (SNG) in dual swirl combustor. The objective of this study is to investigate the flame stabilization, flame structure, fuel compatibility using chemiluminescence measurement in SNG with varying fuel compositions. As experimental conditions, hydrogen content was adjusted from 0 to 11%. Experimental results show that the addition of hydrogen has a major effect on flame behavior due to the higher burning rates associated with hydrogen consequently, The higher reaction activity of hydrogen has extended lean blow-off limit. Especially, DI flame limit has improved more 12.1%.