• Corrosion Science and Technology
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• v.8 no.1
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• pp.21-26
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• 2009

The influence of $H_2S$ on the corrosion of iron and the corrosion prevention mechanism of an inhibitor was investigated with a differential capacitance measurement and a weight loss measurement method. The results show that $H_2S$ accelerates both the anodic iron dissolution and the cathodic hydrogen evolution in most cases. However, $H_2S$ acts as an inhibitor of the corrosion of iron under certain special conditions. An EIS method is proposed to explain the ability of inhibitors.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.90-96
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• 1989

This experiments were conducted to investigate the effect of plant growth regulator treatments on the ethylene evolution in soybean sprouts. Major results can be summarized as follows. 1. IAA showed no significant effect on the ethylene evolution in soybean sprouts. 2. BA increased significantly ethylene evolution while kinetin, zeatin, zeatin riboside were less effective on the ethylene production in soybean sprouts. 3. As the BA concentration was increased, the ethylene evolution was increased. 4. BA increased ethylene production more effectively at earlier stages while 4PU-30 was more effective for ethylene production rather continuously. 5. The order of effectiveness of cytokinins and auxin on the ethylene evolution was as follows : BA 25 ppm>BA 25ppm+IAA 25ppm${\geq}$4PU-30 25ppm>IAA 25ppm>control. 6. It can be concluded that BA was the most effective in inhibiting lateral roots, among the cytokinins tested, and resulted in the biggest diameter of hypocotyl by the ethylene evolution stimulated by BA treatment.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.3.1-3.1
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• 2010

Water splitting reaction using photocatalysts is of great interest in the utilization of solar energy [1]. In the present work, visible light-responsive $TiO_2$ thin films (Vis-$TiO_2$) were prepared by a radio frequency magnetron sputtering (RF-MS) deposition method and applied for the separate evolution of $H_2$ and $O_2$ from water as well as the photofuel cell. Special attentions will be focused on the effect of HF treatment of Vis-$TiO_2$ thin films on their photocatalytic activities. Vis-$TiO_2$ thin films were prepared by an RF-MS method using a calcined $TiO_2$ plate and Ar as the sputtering gas. The Vis-$TiO_2$ thin films were then deposited on the Ti foil substrate with the substrate temperature at 873 K (Vis-$TiO_2$/Ti). Vis-$TiO_2$/Ti thin films were immersed in a 0.045 vol% HF solution at room temperature. The effect of HF treatments on the activity of Vis-$TiO_2$/Ti thin films for the photocatalytic water splitting reaction have been investigated. Vis-$TiO_2$/Ti thin films treated with HF solution (HF-Vis-$TiO_2$/Ti) exhibited remarkable enhancement in the photocatalytic activity for $H_2$ evolution from a methanol aqueous solution as well as in the photoelectrochemical performance under visible light irradiation as compared with the untreated Vis-$TiO_2$/Ti thin films. Moreover, Pt-loaded HF-Vis-$TiO_2$/Ti thin films act as efficient and stable photocatalysts for the separate evolution of $H_2$ and $O_2$ from water under visible light irradiation in the presence of chemical bias. Thus, HF treatment was found to be an effective way to improve the photocatalytic activity of Vis-$TiO_2$/Ti thin films. Furthermore, unique separate type photofuel cell was fabricated using a Vis-$TiO_2$ thin film as an electrode, which can generate electrical power under solar light irradiation by using various kinds of biomass derivatives as fuel. It was found that the introduction of an iodine ($I^-/{I_3}^-$) redox solution at the cathode side enables the development of a highly efficient photofuel cell which can utilize a cost-efficient carbon electrode as an alternative to the Pt cathode.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.211-216
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• 1983

Rhodopseudomonas sphaeroides K-7 evolves large quantities of molecular hydrogen under anaerobic and light illuminated conditions in the presence of utilizable organic compounds as electron donors. Photoevolution of molecular hydrogen was strictly dependent on light as the activity of nitrogenase in this organism. Both of these were inhibited to the nearly same extent at varying concentrations of ammonium ion which also depressed nitrogenase synthesis. In the reaction mixtures devoid of molybdenum ion which is known as the component of nitrogenase, hydrogen evolution also decreased similarly like nitrogenase activity. Photoevolution of molecular hydrogen appeared to have no relationship with hydrogenase activity and bacteriocholophyll content and it was markedly inhibited under the atmosphere of $C_2$H$_2$, $N_2$ or $O_2$. The results strongly indicate that hydrogen evolution by R. sphaeroides K-7 might be catalyzed by nitrogenase. Both hydrogen evolution and nitrogenase activity were largely influenced by the nutritional history of the resting cells. From which we propose that glutamate might play an important role in the regulation of nigrogenase activity in vivo.

• Journal of the Korean Chemical Society
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• v.26 no.3
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• pp.155-159
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• 1982

The new molybdenum(Ⅴ)-triethylenetetraamine complexes such as Trien$H_4(MoOCl_5)_2,\;(MoOCl_3)_2$(trien), and$Mo_2O_4Cl_2$ (trien) have been prepared, and the chemical, magnetic and spectroscopic properties of the complexes have been investigated. Trien$H_4(MoOCl_5)_2has been isolated as green crystal and from this salt the nonelectrolytic and paramagnetic complexes,$(MoOCl_3)_2$ (trien) have been prepared by evolution of hydrogen chloride in anhydrous ethanol. Hydrolysis of triethylenetetraammonium oxopentachloromolybdate(V) yielded the nonelectrolytic and dismagnetic complex, $Mo_2O_4Cl_2$(trien) as brown solid.

• Animal Systematics, Evolution and Diversity
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• v.20 no.2
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• pp.185-189
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• 2004

Taxonomic study for the comantulid crinoids collected from Korea Strait was conducted. A oligophreatan species, Parametra orion (A. H. Clark, 1907) belonging to the family Thalassometridae, was identified and turned out to be new to the Korean fauna. The family Thalassometridae is newly reported in Korea.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.112-113
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• 2003

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1139-1150
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• 1999

The evolution of silica aggregate particles in coflow diffusion flames has been studied experimentally using light scattering and thermophoretic sampling techniques. The measurements of scattering cross section from $90^{\circ}$ light scattering have been utilized to calculate the aggregate number density and volume fraction using with combination of measuring the particle size and morphology through the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh-Debye-Gans and Mie theory for fractal aggregates and spherical particles, respectively. Of particular interests are the effects of flame temperature on the evolution of silica aggregate particles. As the flow rate of $H_2$ increases, the primary particle diameters of silica aggregates have been first decreased, but, further increase of $H_2$ flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal aggregates finally become spherical particles. The variation of primary particle size along the upward jet centerline and the effect of burner configuration have also been studied.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.308-317
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• 2015

To investigate the effect of microstructure on the formation of the desorption peak, the volumetric thermal analysis technique (VTA) was applied to the Mg-13.5 wt% Ni hydride system. The sample made by the HCS (hydriding combustion synthesis) process had two kinds of Mg microstructures. Linear heating was started with various constant heating rates. Only one peak was appeared in the case of the small initial hydrogen wt% (0.83 wt%). Yet, two peaks were appeared with increasing initial hydrogen wt% (1.85 and 3.73 wt%) when only Mg was hydrogenated. The first peak was formed through the evolution of hydrogen from $MgH_2$, made by eutectic Mg. The second peak was formed through the evolution of hydrogen from $MgH_2$, made by primary Mg. Therefore, this result shows that the microstructure also has a considerable effect on forming the desorption peak. We have also derived the hydrogen desorption equations by VTA to get apparent activation energy when the rate-controlling step for the desorption of the hydrided system is the diffusion of hydrogen through the ${\alpha}$ phase and the chemical reaction ${\beta}{\rightarrow}{\alpha}$.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.85.1-85.1
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• 2012

Energetic outflow from active galactic nuclei (AGNs) may play a critical role in galaxy evolution. We present a velocity diagnostics for detecting gas outflow in the narrow-line region of Type-2 AGNs using line-of-sight velocity offset of the [O III]${\lambda}5007$ and $H{\alpha}$ emission lines with respect to the systemic velocity of stars in host galaxies. We apply the diagnostics to nearby galaxies at 0.02 < z < 0.05: 3775 AGN-host and 907 star-forming galaxies as a comparison sample, which are selected from the Sloan Digital Sky Survey DR7. After obtaining a best-fit stellar population model for the continuum and a systemic velocity based on stellar lines, we subtract stellar component to measure velocity offsets of each emission line. We find a sample of 169 AGN-host galaxies with outflow signatures, displaying a larger velocity shift of [O III] than that of $H{\alpha}$, as expected in a decelerating outflow model. We find that the offset velocity of [O III] increases with Eddington ratio, suggesting that gas outflow depends on the energetics of AGN.