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李吉春,沈基五 단국대학교 1995 論文集 Vol.29 No.-
A study on the effect of the angle between the channel and the bridge piers on the increase in water level in the case of a sloped channel was carried out and the following conclusions were made. When the angle between the channel and the piers of 0°was taken as reference, the percentage rise in water level with the incline exhibited a maximum at 45°. That is the grater the slope, the more intense was the percentage rise in the water level; 11%, 5%, 3% and 3% when the slope was 1/200, 1/300, 1/400 and 1/500 respectively. When the percentage rise in the water level with the magnitude of the angle between the channel and the piers was averaged over various slopes, the average increase was 2.3%, 4.5% and 5.5% for 15°, 30° and 45° showing a gradual increase. Application of the Froude number, which is a characteristic factor of an open channel, suggested that the flow of water was inferior when the slope was steeper, while the opposite condition was observed when no hydraulic structures (piers) were present. Since increases in the slope and the angle between the channel and the piers restrict the flow of water, care must be exercised in the design of hydraulic structures, especially those for urban small channels, when steep slopes and excessive angles between the channel and the piers are to be utilized.
Pressure-enhanced dehydrogenation reaction of the LiBH<sub>4</sub>–YH<sub>3</sub> composite
Kim, Kee-Bum,Shim, Jae-Hyeok,Cho, Young Whan,Oh, Kyu Hwan Royal Society of Chemistry 2011 Chemical communications Vol.47 No.35
<P>The increase in hydrogen back pressure unexpectedly enhances the overall dehydrogenation reaction rate of the 4LiBH<SUB>4</SUB> + YH<SUB>3</SUB> composite significantly. Also, argon back pressure has a similar influence on the composite. Gas back pressure seems to enhance the dehydrogenation reaction by kinetically suppressing the formation of the diborane by-product.</P> <P>Graphic Abstract</P><P>The increase in gas back pressure significantly enhances the dehydrogenation reaction of the 4LiBH<SUB>4</SUB> + YH<SUB>3</SUB> composite. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cc14072h'> </P>
Kim, Kee-Bum,Shim, Jae-Hyeok,Oh, Kyu Hwan,Cho, Young Whan American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.16
<P>This article investigates the dehydrogenation behavior of the LiBH<SUB>4</SUB>–YH<SUB>3</SUB> composite under various early-stage Ar back-pressure conditions. It is clearly observed that a minute change in early-stage atmosphere greatly affects the overall dehydrogenation reaction of the composite. Free boron and Li<SUB>2</SUB>B<SUB>12</SUB>H<SUB>12</SUB> start to form in turn as the partial dehydrogenation products around 400 °C under static vacuum or low Ar back pressure. The formation of Li<SUB>2</SUB>B<SUB>12</SUB>H<SUB>12</SUB> greatly increases the activation energy for the dehydrogenation reaction between LiBH<SUB>4</SUB> and YH<SUB>3</SUB> into LiH and YB<SUB>4</SUB>, hence significantly retarding the reaction. The formation of B just slightly increases the incubation period of the reaction. The formation of Li<SUB>2</SUB>B<SUB>12</SUB>H<SUB>12</SUB> is effectively suppressed by initially applying Ar back pressure above 0.1 MPa.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-16/jp4000208/production/images/medium/jp-2013-000208_0007.gif'></P>
Kim, Kee-Bum,Shim, Jae-Hyeok,Park, So-Hyun,Choi, In-Suk,Oh, Kyu Hwan,Cho, Young Whan American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.18
<P>This paper investigates dehydrogenation reaction behavior of the LiBH4-MgH2 composite at 450 degrees C under various hydrogen and argon back-pressure conditions. While the individual decompositions of LiBH4 and MgH2 simultaneously occur under 0.1 MPa H-2, the dehydrogenation of MgH2 into Mg first takes place and subsequent reaction between LiBH4 and Mg into LiH and MgB2 after an incubation period under 0.5 MPa H-2. Under 1 MPa H-2, enhanced dehydrogenation kinetics for the same reaction pathway as that under 0.5 MPa H-2 is obtained without the incubation period. However, the dehydrogenation reaction is significantly suppressed under 2 MPa H-2. The formation of Li2B12H12 as an intermediate product during dehydrogenation seems to be responsible for the incubation period. The degradation in hydrogen capacity during hydrogen sorption cycles is not prevented with dehydrogenation under 1 MPa H-2, which effectively suppresses the formation of Li2B12H12. The overall dehydrogenation behavior under argon pressure conditions is similar to that at hydrogen pressure conditions, except that under 2 MPa Ar.</P>