• 전기학회논문지
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• 제62권5호
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• pp.649-656
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• 2013

A conventional epoxy-microsilica composite (EMC) and an epoxy-microsilica-nanosilicate composite (EMNC) were prepared in order to apply them to mold-type transformers, current transformers (CT) and potential transformers (PT). Nanosilicate was exfoliated in a epoxy resin using our electric field dispersion process and AC insulation breakdown strength at $30{\sim}150^{\circ}C$, glass transition temperature and viscoelasticity were studied. AC insulation breakdown strength of EMNC was higher than that of EMC and that value of EMNC was far higher at high temperature. Glass transition temperature and viscoelasticity property of EMNC was higher than those of EMC at high temperature. These results was due to the even dispersion of nanosilicates among the nanosilicas, which could be observed using transmission electron microscopy (TEM). That is, the nanosilicates interrupt the electron transfer and restrict the mobility of the epoxy chains.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.160-161
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• 2006

To Improve the mean-life and the reliability of power cable, we have investigated thermal conductivity of XLPE insulator and semiconducting materials in l54[kV] underground power transmission cable. Specimens were made of sheet form with the nine of specimens for measurement. Thermal conductivity were measured by Nano Flash Diffusivity thermal conductivity measurement temperature ranges of XLPE insulator were from 20[$^{\circ}C$] to 90[$^{\circ}C$], and the heating rate was 1[$^{\circ}C$/mm]. In case of semiconducting materials. the measurement temperature ranges of thermal conductivity were from 20[$^{\circ}C$] to 60[$^{\circ}C$], and the heating rate was 1[$^{\circ}C$/min].

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.357-357
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• 2006

Many industrial sources of proteins can be used as raw materials to produce films, molded materials, and various hollow items either by "casting" techniques or by "thermoplastic processing". Combining proteins with natural fibbers, paper or biodegradable polyesters is very promising to form biodegradable composites witch take advantage of the barrier and mechanical properties of each component. Using nano-fillers to form nanocomposites has also been shown to be interesting to improve properties. Production, with low transformation cost, of protein based materials to form biodegradable materials with controlled functional properties for food uses, medical uses, packaging, agriculture, controlled release systems, etc. is discussed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.103.1-103.1
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• 2011

고체 산화물 연료전지(SOFC)는 크게 음극(anode), 양극(cathode), 전해질(electrolyte)로 구성되 있으며 연결자를 통해 직렬 또는 병렬로 연결된 형태로 발전장치 등에 활용되고 있다. 이중 연료의 산화반응을 담당하고 있는 연료전지의 음극으로 지금까지 Cobalt, Platinum, Palladium 등의 전이금속 또는 귀금속들이 사용되었지만 현재는 Nickel 또는 Nickel을 함유한 물질들 특히, Ni-YSZ 복합체가 주로 사용되고 있다. Ni-YSZ 복합체는 가격과 성능 등 여러가지 면에서 SOFC의 음극으로 사용하기에 가장 적합한 물질인데 특히 전지의 지지체 역할과 동시에 전극으로서의 역할도 병행해야하는 음극 지지형 SOFC의 경우 Ni-YSZ 복합체의 효용성을 더욱 커지게 된다. 본 연구에서는 SOFC의 음극물질로 가장 널리 쓰이고 있는 Ni-YSZ 복합체를 core shell 형태로 만들어 전도 path를 효율적으로 하고 그 특성을 최적화하기 위한 미세구조 및 소결 거동, 전기적 특성을 평가하였다.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.100-103
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• 2010

In this study, NO reduction behaviors of copper-loaded mesoporous molecular sieves (Cu/MCM-41) have been investigated. The Cu loading on MCM-41 surfaces was accomplished by a chemical reduction method with different Cu contents (5, 10, 20, and 40%). $N_2/77$ K adsorption isotherm characteristics, including the specific surface area and pore volume, were studied by BET's equation. NO reduction behaviors were confirmed by a gas chromatography. From the experimental results, the Cu loading amount on MCM-41 led to the increase of NO reduction efficiency in spite of decreasing the specific surface area of catalysts. This result indicates that highly ordered porous structure in the MCM-41 and the presence of active metal particles lead the synergistical NO reduction reactions due to the increase in adsorption energy of MCM-41 surfaces by the Cu particles.

• 한국재료학회지
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• 제17권4호
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• pp.236-238
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• 2007

[ 0-3PbTiO_3/P$ ](VDF/TrFE) nanocomposites thin films for passive pyroelectric infrared sensor have been fabricated by two-step spin coating technique. 65 wt% VDF and 35 wt% TrFE was formed to a P(VDF/TrFE) poder Nano size $PbTiO_3$ powder was used. 0-3 connectivity of $PbTiO_3$(VDF/TrFE) composites film is achieved and also observed by SEM photography successfully. The dielectric constant, and pyroelectric coefficient measured and compared with P (VDF/TrFE). A very low dielectric constant (13.48 at 1 kHz) and high enough pyroelectric coefficient (3.101 $nC/cm^2$.k at $50^{circ}C$) neasured. This nanocomposites can be used for a new pyroelectric infrared sensor for better performance.

• Elastomers and Composites
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• 제51권4호
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• pp.280-285
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• 2016

The purpose of this study is to get optimum design and operation conditions of the heating rubber roller for laminating process. The cause of performance degradation of heating rubber roller is delamination of rubber on metal tube, rubber aging due to high temperature. We measured the material properties of thermal expansion, thermal conductivity, specific heat and density and analyzed thermal distributions of rubber layer using finite element method. As a result of heat/flow analysis, the density distribution of heating coil must shorten the stabilization time by reducing the temperature deviation on the length direction at the temperature rising section after increasing the density of the area contacting with the laminate film at the center part which is an opposite of the current composition while enabling to maintain the temperature of heater to be consistent while maintaining the temperature deviation to be low when heat loss is created. Finally, we determined optimum heating method of heating rubber roller.

• 한국응용과학기술학회지
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• 제28권2호
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• pp.185-195
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• 2011

Carbon nanotube(CNT) plays an essential role in various fields of nano based science and technology. Recently, silica coated CNT composites are interested because they are useful for the optical, magnetical, and catalytic applications. In this report, carboxyl groups were introduced on the MWCNT using nitric acid. In order to maximize the silica encapsulation efficiency, carboxyl groups of MWCNT reacted with a silane coupling agent were used to prepare silica coated MWCNT. Due to their strong interaction between modified MWCNT and TEOS. Silica layer with a controllable thickness was achieved. Silica coated MWCNT were further utilized as the template for the synthesis of hollow silica nanotubes after $800^{\circ}C$ calcination.

• 한국해양공학회지
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• 제27권2호
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• pp.114-120
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• 2013

A superhydrophobic surface means that the contact angle between the solid surface and a water droplet is more than $150^{\circ}$. Materials with a superhydrophobic surface have a self-cleaning function because of the Lotus effect, in which water is not absorbed by the material but rolls off of it. If such a Lotus effect can be applied to the surface of underwater vessels, submarines, torpedos, and so on, enhanced vessels can be made based on this lubricant effect reducing the friction coefficient for the liquid. Because polymer composites can be easily applied in various nanotechniques, they are more advantageous than conventional materials like iron in terms of a superhydrophobic surface. Furthermore, a superhydrophobic surface bring enhanced anticorrosion and ecotechnology because no paint is needed on underwater vessels.

• Carbon letters
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• 제13권1호
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• pp.48-50
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• 2012

Mass production of graphene-based materials, which have high specific surface area, is of importance for industrial applications. Herein, we report on a facile approach to produce thermally modified graphene oxide (TMG) in large quantities. We performed this experiment with a hot plate under environments that have relatively low temperature and no using inert gas. TMG materials showed a high specific surface area (430 $m^2g^{-1}$). Successful reduction was confirmed by elemental analysis, X-ray photoelectron spectroscopy, thermogravimetic analysis, and X-ray diffraction. The resulting materials might be useful for various applications such as in rechargeable batteries, as hydrogen storage materials, as nano-fillers in composites, in ultracapacitors, and in chemical/bio sensors.