• 대한금속재료학회지
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• 제48권12호
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• pp.1123-1129
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• 2010

In order to apply the Sievert's type automatic apparatus to thermal analysis of hydrogen absorbing materials, the dehydrogenation of the Mg-H system was investigated. As the initial wt% of hydrogen was increased to 4.4, the peak temperature of evolution rate shifted to higher temperature. However, with the initial wt% of hydrogen higher than 4.4, peak temperature of evolution rate did not change. The peak temperatures of evolution rate obtained by automatic apparatus were almost the same as those measured by a manual apparatus. As the heating rate was increased, the peak temperatures increased; the peak temperatures for heating rates 1, 2 and 3 K/min were 664, 687 and 702 K, respectively. The activation energy for the decomposition of Mg hydride was 101 kJ/mol. The Sievert's type automatic apparatus can be successively applied to the thermal analysis of metal hydride.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.662-665
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• 1991

In order to prepare new chiral borohydrides (4) possessing chirality on dialkyl moieties, a series of B-alkoxydiisopinocampheylborinates (3) were synthesized by treatment of diisopinocampheylborane ($Ipc_2BH$) with alcohols (R in ROH: Me, Et, i-Pr, t-Bu) and reacted with excess of potassium hydride. Of these chiral borinic esters, only B-methoxydiisopinocampheyl borinate (3a) was converted into the corresponding dialkylmonoalkoxyborohydride (4a). For the other borinic esters, hydride uptake reactions were very slow at room temperature, accompanying disproportionation products at $65^{\circ}C$. The hydride (4a) formed is stable at $0^{\circ}C$ and can be stored over potassium hydride for few months. In the asymmetric reduction of the selected ketones, 4a provided the corresponding alcohols, such as 21% ee for 3-methyl-2-butanone, 11% ee for 2,2-dimethylcyclopentanone, 24% ee for acetophenone, 32% ee for 3-acetylpyridine, 30% for methyl benzoylformate, 31% ee for 4-phenyl-3-butyn-2-one, 39% ee for 3-butyn-2-one, and 34% ee for 3-hexyn-2-one.

• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.670-676
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• 1992

A systematic study of the partial reduction of carboxylic acids and their derivatives to the corresponding aldehydes with lithium tris(dialkylamino)aluminum hydrides under practical conditions has been carried out. The diethylaminosubstituted derivative of lithium aluminum hydride, lithium tris(diethylamino)aluminum hydride (LTDEA), shows quite general applicability in the conversion of carboxylic acids, carboxylic esters, and primary carboxamides to the corresponding aldehydes. Lithium tripiperidinoaluminum hydride (LTPDA) also appears to be a reagent of choice for such partial transformation of primary carboxamides. In additioin, both LTDEA and LTPDA reduce tertiary carboxyamides to aldehydes in high yields. Finally, lithium tris(dihexylamino)aluminum hydride (LTDHA) is capable of achieving the chemoselective reduction of aromatic nitriles to aldehydes in the presence of aliphatic nitriles under practical conditions.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 춘계학술발표회요약집
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• pp.292.1-292
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• 2001

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3891-3894
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• 2013

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3463-3466
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• 2013

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.260.2-260
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• 1999

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.77-78
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• 2018

• 한국해양공학회지
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• 제23권2호
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• pp.69-73
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• 2009

The objective of this study was to obtain a better understanding of the delayed hydride cracking (DHC) of Zr-2.5Nb alloy. The DHC model has some defects: first, it cannot explain why the DHC velocity (DHCV) becomes constant regardless of an applied stress intensity factor, even though the stress gradient is affected by the applied stress intensity factor at the notch tip. Second, it cannot explain why the DHCV has a strong dependence on the method of approaching the test temperature by a cool-down or a heating-up, even under the same stress gradient, and third, it cannot predict any hydride size effect on the DHC velocity. The DHC tests were conducted on Zr-2.5Nb compact tension specimens with the test temperatures reached by a heating-up method and a cool-down method. Crack velocities were measured in hydrided specimens, which were cooled from solution-treatment temperatures at different rates by being furnace-cooled, water-quenched, and liquid nitrogen-quenched. The resulting hydride size, morphology, and distributions were examined by optical metallography. It was found that fast cooling rates, which produce very finely dispersed hydrides, result in higher crack growth rates. This different DHC behavior of the Zr-2.5Nb tube with the cooling rate after a homogenization treatment is due to the precipitation of the $\gamma$-hydrides only in the water-quenched Zr-2.5Nb tube. This experiment will provide supporting evidence that the terminal solid solubility of a dissolution (TSSD) of $\gamma$-hydrides is higher than that of $\delta$-hydrides.

• 한국수소및신에너지학회논문집
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• 제10권1호
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• pp.41-48
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• 1999

산업단지에서 손실되는 막대한 폐열을 효율적으로 회수하고 이를 인근의 배후 도시에서 활용하기 위해서는 이에 적합한 열수송기술이 필요하다. 현재 온수나 증기에 의한 열수송은 배관을 통하여 열손실 및 마찰손실 등이 발생하므로 수송거리는 3 내지 5km가 한계이다. 그러나 대부분의 공단이 도시지역에서 10km 이상 떨어져 있으므로 이들 지역에서 발생되는 폐열을 적절히 활용하기 위해서는 새로운 열수송시스템이 개발되어야 한다. 본 연구에서는 수소저장합금이 수소를 흡수 또는 방출하면서 발열반응과 흡열반응을 일으키는 특성을 이용하여 산업공단지역의 폐열로부터 수소저장합금의 수소를 방출시키고, 이 수소를 인근 도시지역에 파이프라인으로 수송한 후 필요시 또 다른 수소저장합금과 반응시켜 열을 얻을 수 있는 열수송시스템에 대하여 고찰하였다. 이 시스템에서는 난방의 목적 외에도 수소의 흡수 방출온도가 낮은 합금을 이용하여 냉열을 얻을 수도 있으며, 폐열의 저장수단으로, 또한 수소를 수송함으로서 열수송의 수단으로 활용할 수 있다. 이에 따라 수소저장합금을 이용한 열수송기술의 문제점과 열수송시스템의 구성기술에 대하여도 검토하였다.