• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.568-574
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• 2007

Crack-free dried gel monoliths of the composition $Li_2O1{\cdot}7Al_2O_3{\cdot}8.6SiO_2$ have been prepared as a precursor of transparent glass-ceramic by the hydrolysis and polycondensation of mixed metal alkoxides in solutions containing N,N-dimethylformamide as the drying control chemical additive, alcohols, and water. It was investigated that activation energy for gelation according to the variation of water concentration ranged from 13 to 14 kcal/mol. Only when the amount of water for gelation was 3 times higher than the stoichiometric amount, monolithic dry gels were successfully prepared after drying at $70{\sim}75^{\circ}C$ and at a rate of 0.1~0.3%/h. The specific surface area, the pore volume, the average pore diameters of dried gel at $180^{\circ}C$ were about $239.40m^2/g$, 0.001~0.03 mL/g, and $145.62{\AA}$, respectively. It showed that the dried monolithic gel had a porous body. The DTA curve had the first exothermic peak around $800^{\circ}C$ and the 2nd peak around $980^{\circ}C$, which may correspond to crystallization of the gel.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.2
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• pp.98-108
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• 2010

The purpose of this study was to analyze the monumental expression of Korean War Memorials(KWM) in Korea(KWMK). Through site survey and internet searching, the researcher selected 17 KWMK and analyzed four analysis categories: contents, spatial form, landscape elements, sculptures and architectural elements. The results are as follows: 1. The analysis revealed that main contents of KWMK were to cherish victims of the Korean War, honor military merit, and explain Korean War. 2. Most KWMK built battlefield had the form of symmetry and spatial axis arranged monuments and sculptures for solemnity and heroism. Though the sites were terraced by traditional spatial order, spatial sequence wasn't seen except Yang-gu KWMK and Chumomyeongbi in United Nations Memorial Cemetery in Korea. 3. Stone monument-like towers, tablets, podium, monoliths, cenotaphs, and exhibit halls to explain Korean War and combat history were used as main elements of KWMK and also, war weapons were often displayed the flags of countries taking part in Korean War were raised with Taegeukgi and the United Nations flag. 4. Most sculptures were used as important media to represent the Korean War and assumed realistically the form of heroic combat. But a few architectural memorial built in recent were designed in contemporary style to have spatial sequence and represent Korean War symbolically and narratively. 5. In memorial culture, KWMK were strongly influenced by ideology and patriotism, impacted by conventional value, and designed by some sculptors and designers in a certain circle. Further study will be required to analyze the characteristics of KWMK in the point of design style and diachronic.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.125-131
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• 2024

In this study, synthesized Ni/Ce_xZr_1-xO₂ catalysts were coated on the surface of honeycomb metalic monoliths to investigate catalytic activity in steam reforming of methane reactions. Supports with varying Ce/Zr ratios were synthesized to observe their behavior in the reforming reaction, and catalysts with Ni contents ranging from 5 wt% to 20 wt% were prepared to analyze the effect of Ni loading contents on catalytic activity. The catalysts were characterized by XRD, BET, TPR, and SEM. The TPR analysis indicated the formation of Ni-Ce-Zr oxide with a strong interaction between the active metal Ni and CeO₂-ZrO₂ support. The 15 wt% Ni/Ce_0.80Zr_0.20O₂ catalyst exhibited the highest activity and stability in the steam reforming of methane reaction. Catalysts with enhanced activity and stability were synthesized by manufacturing composite materials using excellent oxygen storage and donor properties of CeO₂ and the thermal properties of ZrO₂.