• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.657-660
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• 2009

The surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ cathode particle was modified by lanthanum based oxide to improve electrochemical property and thermal stability. The XRD pattern of surface layer was indexed with that of $La_4NiLiO_8$. The discharge capacity of modified electrode was higher than that of pristine sample, specially at fast charge-discharge rate and high cut-off voltage. In the DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by surface modification. Such enhancement may by attributed to the presence of stable lanthanum based oxide, which effectively suppressd the reaction between electrode and electrolyte on the surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ electrode.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.66-67
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• 2020

The synthesis of stearic acid composite phase change material (PCM) was investigated and the samples produced were characterized for use in latent heat storage, using a simple chemical sol-gel process. The PCM was encapsulated to tetraethyl orthosilicate by various preparation ratios of stearic acid (5, 10, 15, 20, 30 and 50%). Fourier transformation infrared spectroscope (FT-IR) and X-Ray diffraction (XRD) were performed to determine the chemical structure and crystalloid phase of the microencapsulated PCM. SATEOS1 (5%) shows the best proportion for the PCM. With the presence of stearic acid as core materials and SiO2 as the supporting materials, it does not show any chemical reaction between both of them. SATEOS1 shows promising potential for thermal energy storage as it shows a better encapsulation efficiency and good thermal stability.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.695-698
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• 2012

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1321-1324
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• 2012

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.731-734
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• 2009

• Elastomers and Composites
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• 제42권4호
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• pp.201-208
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• 2007

본 연구에서는 충전된 고무재료의 온도 변화에 대한 치수 안정성을 고찰하기 위해 카본블랙 또는 실리카가 충전된 NR과 SBR의 열변화시 발생하는 수축력과 팽창력을 측정하였다. 일정 길이로 인장된 시편의 온도를 올렸을 때 고무사슬의 엔트로피적 변화에 의해 수축력이 발생하였다. 카본블랙이나 실리카가 첨가된 NR의 경우 충전제 함량이 증가함에 따라 최대 열수축력 값이 감소하였으나, SBR의 경우는 30 phr 함량에서 미충전 고무보다 높은 열수축력 값을 보였다. 압축된 시편의 열팽창력 측정의 경우, 카본블랙을 첨가한 NR의 열팽창력은 거의 변화가 없었으나, SBR은 카본블랙 양의 증가와 함께 최대 팽창력 값이 증가하였다. 실리카를 첨가했을 경우 NR, SBR시편 모두 첨가량이 증가할수록 최대 열팽창력 값이 증가하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.217-217
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• 2011

Recently, demand for thermally stable metal nanoparticles suitable for chemical reactions at high temperatures has increased to the point to require a solution to nanoparticle coalescence. Thermal stability of metal nanoparticles can be achieved by adopting core-shell models and encapsulating supported metal nanoparticles with mesoporous oxides [1,2]. However, to understand the role of metal-support interactions on catalytic activity and for surface analysis of complex structures, we developed a novel catalyst design by coating an ultra-thin layer of titania on Pt supported silica ($SiO_2/Pt@TiO_2$). This structure provides higher metal dispersion (~52% Pt/silica), high thermal stability (~600$^{\circ}C$) and maximization of the interaction between Pt and titania. The high thermal stability of $SiO_2/Pt@TiO_2$ enabled the investigation of CO oxidation studies at high temperatures, including ignition behavior, which is otherwise not possible on bare Pt nanoparticles due to sintering [3]. It was found that this hybrid catalyst exhibited a lower activation energy for CO oxidation because of the metal-support interaction. The concept of an ultra-thin active metal oxide coating on supported nanoparticles opens-up new avenues for synthesis of various hybrid nanocatalysts with combinations of different metals and oxides to investigate important model reactions at high-temperatures and in industrial reactions.

• 한국재료학회지
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• 제29권10호
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• pp.631-638
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• 2019

As automation systems become more common, there is growing interest in functional labeling systems using organic and inorganic hybrid materials. Especially, the demand for thermally and chemically stable labeling paper that can be used in a high temperature environment above $300^{\circ}C$ and a strong acid and base atmosphere is increasing. In this study, a composite coating solution for the development of labeling paper with excellent thermal and chemical stability is prepared by mixing a silica inorganic binder and titanium dioxide. The silica inorganic binder is synthesized using a sol-gel process and mixed with titanium dioxide to improve whiteness at high-temperature. Adhesion between the polyimide substrate and the coating layer is secured and the surface properties of the coating layer, including the thermal and chemical stability, are investigated in detail. The effects of the coating solution dispersion on the surface properties of the coating layer are also analyzed. Finally, it is confirmed that the developed functional labeling paper showed excellent printability.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.612-619
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• 2016

Pitch synthesis reaction was studied based on the effect for chemical composition of feedstock. Feedstock was selected as pyrolyzed fuel oil (PFO) and coal-tar (CT), which are by-products in petroleum and steel industry. Pitch was prepared at $420^{\circ}C$ for 180 minutes on atmospheric pressure by thermal treatment. Thermal stability and softening point (SP) of the prepared pitches were investigated and their molecular weight distribution was analyzed by MALDI-TOF. PFO has various aliphatic compounds and coal-tar has high aromaticity with 3 wt% of primary quinoline insolubles. The thermal property of PFO was enhanced with polymerization reaction during the thermal treatment with increased molecular weight range. But CT was inferior to PFO because of side reaction by hetero elements. CTP was appeared molecular weight by 0~200 m/z.

• 전기화학회지
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• 제12권4호
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• pp.324-328
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• 2009

양극 (cathodes)과 음극 (anodes)이 서로 물리적으로 닿게되는 내부 단락 (internal short-circuit) 현상은 리튬이차전지 안전성 (safety) 이슈의 주요 원인으로 고려되고 있으며, 분리막 (separators)의 열 안정성 (thermal stability)에 의해 크게 영향을 받는 것으로 알려져 있다. 본 연구에서는 기존 폴리올레핀 (polyolefin) 계열 분리막에 비해 열 안정성이 현저히 개선된 세라믹 복합막 구조의 신규 분리막을 개발하여, 전지 내부 단락 발생을 억제하고자 하였다. 본 연구의 복합분리막은 알루미나 ($Al_2O_3$) 나노입자와 PVdF-HFP (polyvinylidene fluoride-hexafluoropropylene) 바인더로 구성된 세라믹 코팅층을, 폴리에틸렌 (polyethylene, PE) 분리막 양면에 도입시킴으로써 제조되었다. 세라믹 코팅층의 모폴로지는 코팅용액의 상전이 (phase inversion) 현상 제어를 통해 결정되었으며, 비용매 (물) 함량이 증가함에 따라 기공크기 및 기공구조가 보다 더 발달되었다. 이러한 세라믹 코팅층의 기공구조 변화는 복합분리막의 열 안정성 및 전기화학특성에 큰 영향을끼치는 것으로 관찰되었으며, 이를 상전이 현상 관점에서 체계적으로 해석하였다.