• Polymer(Korea)
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• v.24 no.3
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• pp.299-305
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• 2000

In order to increase the thermal stability at high temperatures, new hybrid ceramic percursors were synthesized by chemical modification of polycarbosilane (PCS). The structure of hybrid ceramic percursors were investigated by using FT-IR and $^1$H-NMR spectrometers. The syntheses of hybrid ceramic precursors were confirmed by monitoring the change of the adsorption peaks appearing at 0893, 1092, 609 $cm^{-1}$ / on the FT-IR spectra, and also by the presence of peaks at 3.8, 2.0, 0.6 ppm on the $^1$H-NMR spectra. The conversion of hybrid ceramic percursor was around 74 and 10 wt% higher than that of the pure PCS. After the heat-treatment at 150$0^{\circ}C$, the crystalline peaks for $\beta$-SiC were observed at 2$\theta$=35.7, 42.2, 61.0$^{\circ}$ on the X-ray powder diffractogram. It showed the conversion of hybrid ceramic percursor to crystalline $\beta$-SiC.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.107.1-107.1
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• 2011

최근 석유, 가스, 석탄을 비롯한 화석연료의 다량 사용으로 기후변화, 대기오염 등의 환경문제 및 자원 고갈의 우려 때문에 바이오매스는 중요한 화석연료 대체 에너지 자원으로써 큰 관심을 받고 있다. 바이오매스 자원을 에너지로 전환하는 방법 중 하나인 급속 열분해 공정은 산소가 없는 상태에서 바이오매스를 열적으로 분해하여 액상 상태의 생성물을 회수하는 공정으로, 증기상의 열분해 가스를 응축하여 회수하게 된다. 바이오매스의 급속 열분해에 관한 연구는 주로 바이오매스의 종류와 열분해 조건에 따라 회수되는 바이오 원유의 수율 및 물리 화학적 특성에 관한 연구가 수행되고 있으나, 열분해 가스의 응축에 관한 연구는 응축에 수반되는 복잡한 물리적 현상 때문에 미진하다. 따라서 본 연구에서는 바이오매스의 급속 열분해를 통해 생성되는 증기상의 열분해 가스의 응축 현상을 모사 할 수 있는 모델링 기법에 대해 연구하였다. 급속 열분해 공정을 통해 생성되는 바이오 원유는 수백개의 화합물로 구성되어 있으며, 동일한 바이오매스를 사용한 경우라도 공정조건에 따라 바이오 원유에 포함된 화합물은 달라진다. 따라서 본 연구에서는 바이오 원유의 주요 화합물인 water, propanal, butanal, pentanal, phenol, guaiacol, coniferyl alcohol, formic acid, acetic acid, propanoic acid, butanoid acid를 대상으로 열분해 가스의 응축을 모사하였다. 본 연구에서는 응축 모델링 기법의 검증을 위해 실험결과와 비교하여 정확성을 검증하였으며, 본 연구의 결과를 활용하여 응축 조건 변화에 따른 급속 열분해 가스의 응축률을 예측하고, 이를 이용한 응축 열교환기 설계에 유용하게 사용될 수 있을 것으로 판단된다.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.65-78
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• 2016

Initial studies of the photocatalyst has been developed from the field relating to the conversion and storage of solar energy. Recently, the study of the various organic decomposition compound and the water purification and waste water treatment by ultraviolet irradiation in the presence of light or a photocatalyst are being actively investigated. In addition, the oxidized material-carbon nanotubes, graphene-nanocomposites have been studied. Such a complex is suitable as a material constituting the solar cells and photolysis nanoelectronics, including the flexible element due to thermal and chemical stability.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.129-136
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• 2010

Ionic liquids are expanding their applications in various fields of chemistry, due to their unique properties such as negligible volatility, immisciblity with hydrocarbons, high electrical conductivity, and tunable acidity and basicity. In this paper, the physical properties, synthesis, and commercial applications of ionic liquids are discussed. Recent research trends are also briefly reviewed, particularly on application of ionic liquids to catalysis, biomass, and $CO_{2}$ capture and utilization.

• Polymer(Korea)
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• v.29 no.2
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• pp.211-215
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• 2005

Stabilization process is absolutely necessary to convert the precursor fibers into chemically, physically, thermally and structurally stable carbon fibers. Especially, it is critically important for rayon fibers experiencing severe weight loss and thermal shrinkage occurring at the stabilization stage below $400^{\circ}C$. The stabilization of rayon fibers strongly depends not only on stabilization temperature but also on heating rate, chemical pre-treatment, atmosphere, and so on. In the present study, the weight loss, fiber diameter change occurred in the furnace during the stabilization process for rayon fibers produced with various heating rates and in the absence and presence of phosphorous-based flame retardants and the thermal stability of the stabilized fibers were investigated. The result indicates that the weight, diameter and thermal stability of the rayon fibers are significantly affected by the type and amount of the flame retardant used. It is also suggested that the pre-treatment of rayon fibers with a concentration lower than $3\;vol\%$ of phosphoric acid is most desirable for further carbonization process of stabilized rayon fibers.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.46-55
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• 2006

본 연구는 불소그룹을 함유한 술폰화된 아릴렌에테르계 블록 공중합체 고분자 전해질막의 제조 및 연료전지 특성에 관한 것이다. 이러한 불소그룹을 함유한 술폰화된 아랄렌에테르계 블록 공중합체를 제조하기 위하여 양말단에 불소계 비닐기를 가지면서, 고분자 전환시 상온에서 술폰화 가능한 biphenyl계 단량체와 술폰화가 불가능한 sulfonyl계 단량체를 각각 합성하였다. Biphenyl계 단량체로 부터 올리고머를 합성한 후 sulfonyl계 단량체와 열적 고리화 부가중합을 하여 다양한 몰조성을 갖는 일련의 perfluorocyclobutane(PFCB)기를 포함하는 블록 공중합체를 제조하였다. 제조된 블록 공중합체를 상온에서 술폰화제인 chlorosulfonic acid(CSA)를 이용하여 후술폰화시켜 강산 이온기인 sulfonic acid를 biphenyl계 올리고머 부분에 선택적으로 도입하였다. 이렇게 제조된 술폰화된 고분자를 제막한 후 연료전지 특성을 Nafion-115와 비교하였다. 술폰화가 되는 올리고머 블록의 비율 증가에 따라 이온교환능력 (IEC)이 증가하였고 , 그에 따른 팽윤도 역시 증가하는 것을 보였다. 술폰화된 고분자들은 건조 및 습윤 상태에서도 기계적 강도가 우수하였다. 최적화된 술폰화 블록 고분자(S-2) 를 대상으로 membrane electrolyte assembly(MEA) 를 제조하여 연료전지 초기성능을 측정한 결과 Nafion-112와 유사한 전기화학적 성능을 나타내었다.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.670-678
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• 1996

The characterization of catalysts for the selective catalytic reduction(SCR) was investigated to remove NOx discharge from radioactive waste incinerator. The catalyst was prepared by impregnating $V_2O_5$, $MoO_3$, and $SnO_2$ on honeycomb shaped $TiO_2$. The effects of the type of catalysts, reaction temperature, feed composition, and mole ratio of $NH_3/NO$ on the reaction characteristics were evaluated in a laboratory scale reactor. The 10% $V_2O_5/TiO_2$ catalyst showed the highest NO to $N_2$ conversion of 94.4% at $350^{\circ}C$ and the temperature range for higher conversion was broadened by adding thermally stable promoters, $MoO_3$.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.61-66
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• 2020

In this study, the effect of characteristics of colloidal silica, which was used as an additive in the compression/coating catalyst process, on activities and thermal stabilities of the catalysts was investigated. The shape, size, specific surface area and porosity, and composition of four different types of colloidal silica materials were analyzed, and the NOx conversion of V₂O₅/TiO₂ catalyst prepared by these colloidal silica were studied. Properties of the catalysts prepared by colloidal silica depend on the nature of the colloidal silica used, in particular the alkaline substances such as Na in the silica were evaluated to be directly effect on the deNOx conversion of the catalyst. In addition, higher silica contents in the colloidal silica were found to improve the deNOx activity and thermal stability of the catalyst.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.37-42
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• 2021

The effect of chemical composition on the structural and thermal properties of TiZrN thin films was studied. As the Zr fraction in the deposited TixZr1-xN (x = 0.87, 0.82, 0.7, 0.6, and 0.28) increased, microstructural changes consisted of reduction in the grain size and a gradual transition from columnar structure to granular structure were observed. In addition, it was also confirmed that a gradual crystal phase transition from TiN to TiZrN has occurred as the Zr fraction increased up to 0.4. After heat treatment at 900℃, Ti0.82Zr0.18N and Ti0.7Zr0.3N layers were converted to a form in which rutile phase TiO2 and TiZrO4 oxides coexist, while Ti0.6Zr0.4N layer was converted to TiZrO4 oxide. Among the five compositions of TiZrN films, the Ti0.6Zr0.4N showed the best high temperature stability and produced a significant enhancement in the thermal oxidation resistance of Inconel 617 through suppressing the surface diffusion of Cr caused by thermal oxidation of the Inconel 617 substrate.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.990-995
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• 1999

To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with ethylene diamine(EDA) and hexamethylene diamine(HMDA) in a stoichiometrically equivalent ratio. From this work, the effect of linear amine curing agents on the thermal and mechanical properties is significantly influenced by the chemical structure or chain length of curing agents. In contrast, the results show that the DGEBA/EDA system having the two carbons had higher values in the thermal stability, maximum conversion of epoxide, density, glass transition temperature, tensile modulus, flexural strength, and flexural modulus than the DGEBA/HMDA system having the six carbons, whereas the DGEBA/EDA cure system had relatively low values in the shrinkage(%), thermal expansion coefficient, tensile strength, and had similar values in the maximum exothermic temperature, and conversion of epoxide compared to the DGEBA/HMDA cure system. This findings indicate that packing ability in the HMDA structure affects the thermal and mechanical properties.