• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1481-1484
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• 2009

When isolated phenol or a small phenol-solvent cluster is excited to the $S_1\;state\;of\;{\pi}{\pi}^*$ character, the hydrogen atom of the hydroxyl group dissociates via a ${\pi}{\sigma}^*$ state that is repulsive along the O-H bond. We computationally investigated the substitution effects of an amino group on the excited state hydrogen transfer reaction of phenol. The time-dependent density functional theory (TDDFT) with B3LYP functional was employed to calculate the potential energy profiles of the ${\pi}{\pi}^*$ and the ${\pi}{\sigma}^*$ excited states along the O-H coordinate, together with the orbital shape at each point, as the position of the substituent was varied. It was found that the amino substitution has an effect of lowering the ${\pi}{\sigma}^*$ state and enhancing the excited state hydrogen transfer reaction.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.131-137
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• 2003

Backfire occurrence must be controlled for the practical use of hydrogen fueled engine. It was found from preceeding studies that crevice volume around piston rings could effect a backfire occurrence. In this study, a possible countermeasure to backfire occurrence was evaluated by using multi point ignition method around piston ring. The results showed that backfire limited equivalence ratio was increased by a little due to a enhancing effect of mixture combustion around piston crevice volume.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.115-119
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• 2004

This paper is investigated about the effect of vibration of the water surface for hydrogen gas generation by non-thermal plasma. The vibration of the water surface is more powerful with increasing applied voltage. In this experimental reactor which is made of multi-needle and plate, the maximum acquired hydrogen production rate is about 6.8[ml/sec]. Although the generation of hydrogen gas is increased with elevating time, it is saturated after specific time due to the volume of reactor and the saturation of taylor cone.

• Korean Journal of Metals and Materials
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• v.50 no.6
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• pp.445-448
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• 2012

We studied the effect of temperature and reaction time by investigating the various temperatures and reaction times in the reduction of molybdenum oxide ($MoO_3$) to molybdenum (Mo) powder in hydrogen gas. We also studied the effect of the reaction of reduction according to the various hydrogen gas flow rates. We surveyed the reduction from molybdenum oxide to molybdenum powder in hydrogen gas and checked two temperature ranges, one from $400^{\circ}C$ to $600^{\circ}C$ and the other from $700^{\circ}C$ to $900^{\circ}C$. We found that the reaction ratio of molybdenum oxide increased with an increasing temperature and also increased with an increasing reaction time, but hydrogen gas did not influence the reduction ratio of molybdenum oxide. We examined molybdenum powders fabricated by ball milling for two hours, using with X-ray diffraction (XRD) and a scanning electron microscopy (SEM).

• Rapid Communication in Photoscience
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• v.3 no.3
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• pp.56-58
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• 2014

Single-walled carbon nanotubes (SWNTs) catalyzed hydrogen production from water containing various electron donors under visible light (${\lambda}$ > 420 nm). As-received SWNTs were effective for hydrogen production, yet the effect vanished when they underwent surface chemical treatments. Upon coupling with CdSe particles, however, the surface treated SWNTs were far superior to non-treated SWNTs by a factor of ~30 for hydrogen production.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.201-209
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• 2001

The change of optical transmittance of $PdH_x$ thin film due to hydrogen concentration change was measured at room temperature. Pd film($312{\AA}$ thick) was made by thermal evaporation on glass substrate. Hydrogen absorption and desorption cycling effect on optical transmittance was measured 4 times in the pressure range between 0 and 640 torr. Ratio of optical transmittance to the change of ln pressure(torr) increases with increasing number of hydrogen A-D cyclings in the ${\beta}$ phase.

• KSBB Journal
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• v.14 no.3
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• pp.358-364
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• 1999

The effect of hydrogen peroxide on pretreatment of oakwood was investigated. Reaction temperature was $170^{\circ}C$ and reaction solutions used in pretreatment were aqueous ammonia, sulfuric acid and pure water. When 10% ammonia solution was used, the extents of delignification and hemicellulose recovery were 55% and 26%, respectively. These values were significantly higher as delinigfication and lower as hemicellulose recovery than those of acid hydrolysis. To overcome this problem, hydrogen peroxide was added into ammonia solution stream to increase hemicellulose recovery. But delignification and hemicellulose recovery were not increased as much as hydrogen peroxide loading was increased. And as hydrogen peroxide loading was increased, the decomposition of sugars solubilized from hemicellulose and cellulose were increased. So there were significant differences between the total amount in solid residue and liquid hydrolyzate, and the total amount in the original biomass. It was found that hydrogen peroxide added was reacted with substrate packed mostly in the front part of reactor. In order to increase hemicellulose recovery, it was necessary to treat with acidic solution than with alkali solution. Effect of hydrogen peroxide was higher in water than acid solution.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.517-523
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• 2021

The present study aims to investigate the impact of hydrogen-rich water on the lactic acid level in metformin-treated diabetic rats under hypoxia. Thirty Sprague-Dawley rats were randomly divided into five groups, including normal diet group, and diabetes model (DM) group, DM + metformin treatment (DMM) group, DMM + hypoxia treatment (DMMH) group and DMMH + hydrogen-rich water (DMMHR) group. We found that the levels of lactic acid, pyruvate and lactate dehydrogenase were significantly lower in the blood of DMMHR group than DMMH group. Superoxide dismutase and glutathione levels in liver and heart were significantly higher in DMMH group after hydrogen-rich water treatment, while malondialdehyde and oxidized glutathione levels were decreased in DMMHR group when compared with DMMH group, which indicates that hydrogen-rich water could reduce oxidative stress. qPCR analysis demonstrated that that pro-apoptotic genes Bax/Caspase-3 were upregulated in DM group and metformin treatment suppressed their upregulation (DMM group). However, hypoxic condition reversed the effect of metformin on apoptotic gene expression, and hydrogen-rich water showed little effect on these genes under hypoxia. HE staining showed that hydrogen-rich water prevented myocardial fiber damages under hypoxia. In summary, we conclude that hydrogen-rich water could prevent lactate accumulation and reduce oxidant stress in diabetic rat model to prevent hypoxia-induced damages. It could be served as a potential agent for diabetes patients with metformin treatment to prevent lactic acidosis and reduce myocardial damages under hypoxic conditions.

• Journal of Sensor Science and Technology
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• v.21 no.4
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• pp.283-286
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• 2012

This paper presents the optical hydrogen sensor based on transparent 3C-SiC membrane and photovoltaic effect. Gasochromic materials of Pd and Pd/$WO_3$ were deposited by sputter on 3C-SiC membrane for gas sensing area. Gasochromic materials change to transparency by exposure to hydrogen. The variations of light intensity by hydrogen generate the photovoltaic of P-N junction between N-type 3C-SiC and P-type Si. Single layer of Pd shows higher photovoltaic compared with Pd/$WO_3$. However, phase transition from ${\alpha}$ to ${\beta}$ is shown at 6 %. Pd/$WO_3$ structure show the more linear response to hydrogen range of 2 % ~10 %. Also, almost 2 times fast response and recovery characteristics are shown at Pd/$WO_3$. These fast performances are come from the fact that Pd promoted the chemical reaction between hydrogen and $WO_3$.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.491-494
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• 2008

The hydrogen fuel and fuel cell which have high energy efficiency and low pollutant emission are getting interest as an alternative energies due to the fossil fuel exhaust, green house effect and atmospheric pollutant problems. The hydrogen gas is very effective as an alternative energy. But, if it is leaked into the air it forms the mixed gas with the air then the danger of the explosion is risen up. So, the secure the safety is mostly important. In this research, to detect the leakage of the hydrogen rapidly, added the odorant materials which don't include the sulfur component into the hydrogen gas and researched on the effect of each odorant on the performance of the fuel cell. As the results, setting the cumulation electric power on the basis and comparing the pure hydrogen, 2,3-Butanedione 5ppm mixed gas 86.1%, 5-Ethylidene-2-Norbornene 17ppm mixed gas 88.2%, Isovaleraldehyde 10ppm mixed gas 74.8%, Ethyl Isobutyrate 2.2ppm mixed gas 93.5% of performance was shown.