• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1740-1742
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• 2004

산소 과전압이 낮은 $MnO_2$를 촉매로 사용하여 반도체 산화물계의 산소선택성 전극을 제조하고 산화물 코팅층의 미세구조와 전기화학적 특성을 분석하였다. Ti 기판에 열분해 법을 이용하여 $MnO_2$ 피막을 형성하였고, 또한 binder를 이용한 코팅 방법을 이용하여 Ti, Fb 기판에 $MnO_2$ 피막층을 형성하였다. 450$^{\circ}C$에서 1시간 열분해하여 약 1 ${\mu}m$의 $MnO_2$ 피막층을 형성 시켰으나 Ti 기판과의 접착력이 약하여 피막자체에 대한 전기화학적 특성은 관찰할 수 없었다. PVDF : $MnO_2$의 함량비가 1:1에서 1:6 까지는 DMF의 함량에 무관하게 전극 특성이 나타나지 않았지만 20:1 이상의 조성에서는 균일한 C-V 특성을 나타냈고, 산소 발생 과전압도 약 1.4V 정도로 감소되었다. 그러나 Ti 기판의 경우 열분해법을 이용하여 제조된 전극과 같이 낮은 기판과의 접착력 때문에 $MnO_2$ 피막층의 촉매효과가 현저하게 감소하였다.

• Clean Technology
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• v.25 no.3
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• pp.256-262
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• 2019

Hydroxylammonium nitrate (HAN)-based liquid propellants are attracting attention as environmentally friendly propellants because they are not carcinogens and the combustion gases have little toxicity. The catalyst used to decompose the HAN-based liquid propellant in a thruster must have both low temperature activity and high heat resistance. The objective of this study is to prepare an Ru/alumina/metal foam catalyst by supporting alumina slurry on the surface of NiCrAl metal foam using a washing coating method and then to support a ruthenium precursor thereon. The decomposition activity of a HAN aqueous solution of the Ru/alumina/metal foam catalyst was evaluated. The effect of the number of repetitive coatings of alumina slurry on the physical properties of the alumina/metal foam was analyzed. As the number of alumina wash coatings increased, mesopores with a diameter of about 7 nm were well-developed, thereby increasing the surface area and pore volume. It was optimal to repeat the wash coating alumina on the metal foam 12 times to maximize the surface area and pore volume of the alumina/metal foam. Mesopores were also well developed on the surface of the Ru/alumina/metal foam catalyst. It was found that the metal form itself without the active metal and alumina can promote the decomposition reaction of the HAN aqueous solution. In the case of the Ru/alumina/metal foam-550 catalyst, the decomposition onset temperature was significantly lowered compared with that of the thermal decomposition reaction, and ${\Delta}P$ could be greatly increased in the decomposition of the HAN aqueous solution. However, when the catalyst was calcined at $1,200^{\circ}C$, the catalytic activity was lowered inevitably because the surface area and pore volume of the catalyst were drastically reduced and Ru was sintered. Further research is needed to improve the heat resistance of Ru/alumina/metal foam catalysts.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.279-286
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• 2010

Hypersonic aircraft technologies have been developed with increase in flight speeds. As hypersonic flight speeds increase, heat loads on an aircraft and it's engine increase. Researches on cooling technologies using endothermic fuels are progressing in the USA, France, and Russia to treat the heat loads. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. In this study, methylcyclohexane, n-octane, and n-dodecane were selected as model endothermic fuels and experiments in endothermic properties were implemented. Experimental conditions were supercritical phase of each model fuels in which actual endothermic fuels were exposed. The object of this study is to identify endothermic properties of the model endothermic fuels and to predict endothermic properties of actual fuels such as kerosene fuels.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.178-185
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• 2019

Three spherical quaternary composites composed of metal/metal oxide/high explosive/oxidizer were prepared by a crystallization/agglomeration process. From the characteristics of composites by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the shortening of the decomposition zone of high explosives in the quaternary composite was observed, which may be attributed to the autocatalytic reaction caused by $ClO_2$ or HCl which are ammonium perchlorate (AP) degradation products. The activation energy analysis showed that the activation energy abruptly decreases at the end of the decomposition zone of high explosives, and it was considered to be caused by $HNO_2$ which is common in decomposition products of high explosives. The activation energy predicted from complex pyrolysis results by the distributed activation energy model (DAEM) showed much better in accuracy than those by model-fitting methods such as Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models.

• Polymer(Korea)
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• v.26 no.1
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• pp.80-87
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• 2002

A comparative study using electron-beam(EB) and thermal curing techniques was carried out to determine the effect of cure behavior and thermal stability of epoxy resins. In this work, benzylquinoxalinium hexafluoroantimonate(BQH) was used as a latent cationic catalyst for an epoxy resin. According to the thermogravimetric analysis(TGA), the decomposed activation energy based on Coats-Redfern method was higher in the case of thermal curing technique. This could be interpreted in terms of slow thermal diffusion rate resulted from high crosslink density of the thermally cured epoxy resin. However, the increase of hydroxyl group in the epoxy resin cured by EB technique was observed in near-infrared spectroscopy(NIRS) measurements, resulting in improving the stable short aromatic chain structure, integral procedural decomposition temperature, and finally ductile properties for high impact strengths.

• Journal of Integrative Natural Science
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• v.2 no.3
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• pp.177-184
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• 2009

신소재(고분자, 금속, 세라믹)는 기존의 재료와는 다른 우수한 특성과 새로운 기능이 있어 우리 인류 복지에 매우 중요하며 우리는 무한대 생존 경쟁에 몰리고 있다. 이 중 무기고분자는 유기고분자의 단점을 보완하는 동시에 새로운 기능성을 가지므로 산업발전에 매우 중요하다. 다양한 무기고분자의 응용분야 중 세라믹 전구체로의 사용은 첨단 산업 분야에 막대한 발전을 초래하였다. 특히 규소를 함유하는 비산화성 세라믹인 탄화규소 (SiC) 및 질화규소 ($Si_3N_4$) 세라믹은 그 산업적 용도가 다양하다. 규소 고분자는 원료 물질이 값싸고 중합 수율이 높아서 경제적이고, 분자 내 Si와 C 또는 N의 비율을 자유자제로 조정할 수가 있고, 용융성 또는 용해성이 있으므로 성형가공이 가능하며, 세라믹 잔여 수율을 증대시키기 위해서 여러 화학반응에 의해 가교도 시킬 수가 있다. 열분해 조건에 따라서 SiC와 $Si_3N_4$ 등 선택의 조절이 쉬우며, 금속과 섞어서 열분해 함으로서 세멧도 제조할 수가 있다. 이런 종류의 연구는 신소재의 총아인 금속, 고분자, 세라믹 연구들이 함께 어우러진 종합 작품이라 할 수 있겠다. 여러 유형의 유기규소 고분자들을 다양하게 합성해서 그 열분해 과정을 좀 더 면밀히 연구한다면 산업적 응용 가능성은 매우 크리라 기대된다.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.721-730
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• 1993

Various catalysts of $Cu_xH_3-{_{2x}}PMo_{12}O_{40}{\cdot}_nH_2O$ with different x-values have been prepared and characterized by thermal analysis, X-ray powder diffraction, infrared spectroscopy, BET surface-area measurement, electron microscopy, and temperature programmed desorption of ammonia. The properties of these catalysts in acrolein oxidation have been investigated in a continuous-flow fixed-bed reactor. The catalysts lost their water of crystallization at about $200^{\circ}C$ and their constitutional water between 300 and $400^{\circ}C$. The Keggin structure of the catalysts was identified by infrared spectroscopy. The decomposition of Keggin anion, $(PMo_{12}O_{40})^{3-}$, was increased with the increase of substituted copper content and identifiable $MoO_3$ and $P_2O_5$ as decomposition products were observed. The conversion of acrolein decreased with the increase of x probably due to the decrease of specific surface area and of total amount of acid sites. But specific reaction rate and selectivity to acrylic acid were maximized at x=1.0, and it showed specific acid site distributions.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.295-296
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• 2001

동물 축사, 폐수 및 하수처리장, 피혁공장, 생선처리시설 등에서 주로 발생하는 암모니아(NH$_3$) 및 트리메틸아민(($CH_3$)$_3$N)과 같은 악취 물질 제거에 대한 많은 연구가 진행되고 있다. 악취 물질에 대한 처리 기술에는 직접 산화법, 고온 연소법, 효소분해법, 흡착법, 촉매 산화법, 플라즈마 제거법 등과 같은 악취 물질을 분해 제거하는 방법과 단순히 악취를 은폐시키는 마스킹법이 있다. (중략)

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.58-63
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• 2007

The aim of the present work is to study the effect of gallium addition to HZSM-5 on recovery rates of gaseous and liquid products and carbon number distribution in the catalytic cracking of a polymer mixture, LDPE, LLDPE, and EVA copolymer, with a composition similar to that found in real agricultural film wastes. Ga/HZSM-5 system produced a larger amount of aromatic hydrocarbons than HZSM-5. The yield of aromatic compound in vapor phase contact was higher than that in liquid phase contact. The yield of aromatic compound increased with the amount of catalyst and with the reaction temperature of catalyst bed. The effect of gallium addition on the carbon number distribution was not great.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.71-79
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• 2010

As hypersonic flight speeds and engines efficiencies increase, heat loads on an aircraft and it's engine increase. Because the temperature of the air flow is too high to cool the aircraft structure at hypersonic flight speeds, it is essential to use the aircraft fuel as the primary coolant. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. The endothermic reactions are improved by catalysts which change the extent of reaction and product distribution. At high temperature, liquid hydrocarbons would lead to coke formation that can reduce the effectiveness of heat exchanger and cause rapid degradation of the catalyst, thus endothermic capacity of endothermic fuels is limited to the temperature at which coke doesn't form. In this study, the essential cooling technologies by applying endothermic fuels and the properties of the endothermic fuels are described.