• 한국수소및신에너지학회논문집
• /
• 제21권2호
• /
• pp.81-88
• /
• 2010

Hydrogen energy applications have recognized clean materials and high energy carrier. Accordingly, Hydrogen energy applies for fuel cell by Mg and Mg-based materials. Mg and Mg-based materials are lightweight and low cost materials with high hydrogen storage capacity. However, commercial applications of the Mg hydride are currently hinder by its high absorption/desorption temperature, and very slow reaction kinetics. Therefore one of the most methods to improve kinetics focused on addition transition metal oxide. Addition to transition metal oxide in $MgH_x$ powder produce $MgH_x$-metal oxide composition by mechanical alloy and it analyze XRD, EDS, TG/DSC, SEM, and PCT. This report considers kinetics by transition metal oxide rate and Hydrogen pressure. In this research, we can see behavior of hydriding/dehydriding profiles by addition catalyst (transition metal oxide). Results of PCI make a excellent showing $MgH_x$-5wt.% Sc2O3 at 623K, $MgH_x$-10wt.% $Sc_2O_3$ at 573K.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.336-338
• /
• 1997

The anneal behavior of ArF excimer Laser CVD SiON films has been studied using FT-IR absorption spectroscopy. The anneal temperature range was $400{\sim}800^{\circ}C$ Abundant hydrogen effusion from thes layers was observed as anneal temperature increased. The coexistence of both Si-H am N-H bonds offers the possibility for cross linking am evidence for the occurrence of cross lingking was found in the IR spectrum. The electrical properties were also obtained that tire films have low leakage currents am good TZDB properties.

• Macromolecular Research
• /
• 제16권5호
• /
• pp.385-395
• /
• 2008

Synthesis and properties of novel excited-state intramolecular proton transfer (ESIPT) materials, recently developed in our group, are described. Highly efficient ESIPT reaction, achieved in polyquinolines, polybenzoxazoles, and oxadiazole and imidazole derivatives possessing an intramolecular tautomerizable hydrogen bond, has been investigated theoretically and experimentally. It is demonstrated that unique properties arising from the ESIPT process (large Stokes' shift, no self-absorption, and easy population inversion, etc.) make it possible to produce advanced polymer devices for lasing, optical storage, and electroluminescence.

• Elastomers and Composites
• /
• 제25권1호
• /
• pp.13-19
• /
• 1990

The purpose of this study is to estabilish the synthetic condition of polyurhethane elastomer for excellent properties. Polyurethane elastomer which have different NCO percentage and hard segment contents was synthesized by casting method. And the effects of hard segment contents were investigated by analytical methods such as IR, DSC, etc. [NCO]/[OH] ratio was proper at the range $1.02{\sim}1.05$. By IR absorption peak($1250cm^{-1}$) which indicate interurethane hydrogen bond it was confirmed that hard segment were crystallized. Melting point that was determined by DSC showed the effects of hard segment contents, phase mixing and crystalline size.

• 한국수소및신에너지학회논문집
• /
• 제12권1호
• /
• pp.39-50
• /
• 2001

Vanadium based solid solution alloys have been studied as a potential negative electrode of Ni/MH battery due to their high hydrogen storage capacity. In order to improve the kinetic property of V-Ti alloy in KOH electrolyte, the ball-milling process with Ni, which has a catalytic effect of hydrogen absorption/desorption, was carried out to modify the surface properties of V-Ti-Cr alloys with high hydrogen storage capacity. Moreover, to overcome the problem of poor cycle life, V-Ti alloy substituted by Cr, V0.68 Ti0.20 Cr0.12, has been developed showing a good cycle performance (keeping about 80 % of initial discharge capacity after 200 cycles). The cycle life of surface-modified V0.68 Ti0.20 Cr0.12 alloy was improved by suppressing the formation of TiO2 layer on the alloy surface while decreasing the amount of dissolved vanadium in the KOH electrolyte. In order to promote the effect of Ni coating on the surface property of V0.68 Ti 0.20 Cr 0.12 alloy by ball-milling, filamentary-typed Ni, which has higher surface coverage area than sphere-typed Ni was used as a surface modifier. Consequently, the surface-modified V0.68 Ti0.20 Cr0.12 alloy electrode showed a improved discharge capacity of 460 mAh/g.

• 한국재료학회지
• /
• 제29권1호
• /
• pp.1-6
• /
• 2019

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide($Cu_2O$) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of $Cu_2O$ is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of $Cu_2O$ while imperfections of the $Cu_2O$ thin films are removed. This study investigates the photoelectrochemical properties of $Cu_2O$. However, severe photo-induced corrosion impedes the use of $Cu_2O$ as a photoelectrode. Two candidates, $TiO_2$ and $SnO_2$, are selected for the passivation layer on $Cu_2O$ by by considering the Pourbaix-diagram. $TiO_2$ and $SnO_2$ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that $SnO_2$ is a good passivation layer for $Cu_2O$.

• 한국세라믹학회지
• /
• 제55권6호
• /
• pp.597-607
• /
• 2018

In this study, a wet chemical method was used to synthesize nanostructured hydroxyapatite for biomedical applications. Diammonium hydrogen phosphate and calcium nitrate 4-hydrate were used as starting materials with a sodium hydroxide solution as an agent for pH adjustment. Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, differential thermal analysis, thermal gravimetric analysis, atomic absorption spectroscopy, and ethylenediaminetetraacetic acid (EDTA) titration analysis were used to characterize the synthesized powders. Having been uniaxially pressed, the powders formed a disk-like shape. The sinterability and electrical properties of the samples were examined, and the three-point bending test allowed for the measurement of their mechanical properties. Sedimentation analysis was used to analyze the slurry ability of hydroxyapatite. As in-vitro biological properties of the samples, biocompatibility and cytotoxicity were assessed using osteoblast-like cells and the L929 cell line, respectively. Solubility was assessed by employing a simulated body fluid.

• 한국재료학회지
• /
• 제24권3호
• /
• pp.129-134
• /
• 2014

Pure $MgH_2$ was milled under a hydrogen atmosphere (reactive mechanical grinding, RMG). The hydrogen storage properties of the prepared samples were studied at a relatively low temperature of 423 K and were compared with those of pure Mg. The hydriding rate of the Mg was extremely low (0.0008 wt% H/min at n = 4), and the $MgH_2$ after RMG had higher hydriding rates than that of Mg at 423 K under 12 bar $H_2$. The initial hydriding rate of $MgH_2$ after RMG at 423 K under 12 bar $H_2$ was the highest (0.08 wt% H/min) at n = 2. At n = 2, the $MgH_2$ after RMG absorbed 0.39 wt% H for 5 min, and 1.21 wt% H for 60 min at 423K under 12 bar $H_2$. At 573 K under 12 bar $H_2$, the $MgH_2$ after RMG absorbed 4.86 wt% H for 5 min, and 5.52 wt% H for 60 min at n = 2. At 573 K and 423 K under 1.0 bar $H_2$, the $MgH_2$ after RMG and the Mg did not release hydrogen. The decrease in particle size and creation of defects by reactive mechanical grinding are believed to have led to the increase in the hydriding rate of the $MgH_2$ after RMG at a relatively low temperature of 423 K.

• Journal of Photoscience
• /
• 제6권4호
• /
• pp.165-170
• /
• 1999

Asymmetric recognition of chiral alcohol by fluorenone derivatives with chiral substituents through intermolecular hydrogen bonding interaction in the singlet excited state was attempted. 1-((1S, 2R, 5S)-(+)-Menthyloxycarbonyl)aminofluoren-9-one (1-MAF) and 1-((1S, 2R, 5S)-(+)-menthyloxycarbonyl)oxyfluoren-9-one (1-MOF) were synthesized and their photophysical behaviors were characterized by the measurement of absorption and fluorescence spectra, as well as the quantum yield and the lifetime of fluorescence. The excited singlet states of 1-MAF and 1-MOF were revealed to have characteristics similar to those of fluorenone, though the intramolecular CT nature was fairly suppressed as compared with 3- and 4-substituted aminofluorenones. Fluorescences of 1-MAF and 1-MOF in acetonitrile were quenched by the addition of alcohols. Differences in fluorescence quenching efficiency were hardly observe for rather small chiral alcohols such as (R)-(-)- or (S)-(+)-2-butanol, while bulky alcohols such as menthol and isopinocampheol showed chiral recognition effects in their fluorescence quenching of 1-MAF in either acetonitrile or butyronitrile.

• 대한치과기공학회지
• /
• 제15권1호
• /
• pp.5-25
• /
• 1993

Effects of hydrogenation on microstructure and mechanical properties of pure Ti and Ti-0.15Pd alloy have been studied by means of optical microscopy, differential scanning calorimeter(DSC), Xray diffraction and micro vicker's hardness test. Grain size of pure Ti and Ti-0.15Pd alloy decresed largely by hydrogenation finer than that of pure Ti and the grain size refinement was evedent in Ti-0.15Pd alloy than that in pure Ti. Ti-.015Pd alloy carried out solution treatment at 950$^{\circ}C$, the transformation of $\alpha$' martensite was occured. The amount of Hydrogen absorption in Ti-.015Pd alloy was higher than that in pure Ti. Decomposition of hydride in pure titanium and Ti-0.15Pd alloy increased largely by hydrogenation, and micro vicker's hardness of Ti-.015Pd alloy was largely than that of pure Ti by 30% after hydrogenation. The micro vicker's hardness of Ti-0.15Pd alloy after solution treatment and dehydrogenation were higher at $\beta$ phase ranger(950$^{\circ}C$) than that phase range(750$^{\circ}C$).