• 한국안전학회지
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• 제21권1호
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• pp.79-85
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• 2006

Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

• 한국정밀공학회지
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• 제12권11호
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• pp.132-139
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• 1995

Turbulent boundary layer pressure fluctuation exerted on the surface of a structure can give rise to a elastic stress wave on the surface of the structure. The stress wave so called surface wave, will not only propagate along the surface of structure but also penerate into the structure. To reduce the transmission of stress wave into the structure the elastomer layer is usually attactched on the surface of structure. The transfer function, which is defined herein as the ratio of stress waves at the surface and bottom of the elastomer layer, is derved by use of the cylindrical coordinates system. The elastodynamics of the elastomer layer subjected to the turbulent boundary layer pressure fluctuation is represented by the simplified one degree-of-freedom model for easy prediction of the stress wave transmission as well as efficient design of the elastomer layer.

• 한국세라믹학회지
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• 제39권10호
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• pp.919-927
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• 2002

표면층과 내부간의 기공구조가 다른 다공질체를 제조하기 위해 입자크기가 다른 두 종류의 분체를 이용하여 다공질 성형체를 제조하였다. 두 층간의 소결 수축율을 동일하게 제어하기 위해 성형밀도 변화에 따른 소결밀도 변화를 예측할 수 있는 Ford＇s equation을 도입하여 소결 수축율을 동일한 조건을 구하였다. 제조된 다공질체는 미세구조와 통기도를 조사함으로서 기공의 이중 구조화 여부를 평가하였다. SEM 관찰결과 기공크기가 다른 두 층으로 구성되어 있는 것을 확인하였다. 각 층의 통기도는 출발 입자크기와 기공율이 클수록 증가하였으며, 이중 기공구조를 갖는 시편의 통기도는 기공크기가 작은 층의 특성에 의존하였다.

• Journal of Magnetics
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• 제2권4호
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• pp.126-129
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• 1997

We have studied magnetostructural phase transitions in the perovskite-type layered structure compound (C18H37NH3)2 MnCl4 by means of electron paramagnetic resonance (EPR) and superconducting quantum interference device (SQUID) measurements. Distinct slopes were observed in the linear temperature dependences of the Mn++ EPR linewidth in the low and high temperature phases. Besides, linewidth anomalies at the transition temperatures sensitively reflect the magnetic changes arising from the MnCl6 octahedra.

• Bulletin of the Korean Chemical Society
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• 제16권6호
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• pp.484-489
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• 1995

The synthesis of new bismuth-barium containing members of layered cuprates with 2201 type structure was reported. By solution calorimetry the formation enthalpies for Bi2MLaCuO6.5 (M=Ba, Ba0.5Sr0.5, Sr) were obtained. Crucial influence of partial oxygen pressure and size of lanthanoid on stability of layered cuprates was shown. Electronic states of variable valence atoms were studied by voltammetry of solids.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2004년도 학술대회지
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• pp.6-6
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• 2004

• 한국전자파학회논문지
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• 제14권7호
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• pp.712-720
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• 2003

본 논문에서는 원형 편파의 구형 빔 패턴을 효율적으로 형성하기 위하여 교차 다이폴 소자로 여기되는 다층 원형 도체 배열 구조(MDAS)를 제안하였다. 다이폴 방사 소자 여기에 의한 MDAS는 전체 배열 안테나의 부피 및 무게를 줄일 수 있는 장점이 있으므로 비교적 낮은 주파수 대역 응용에 적합하다. 이러한 구조의 유효성을 검증하기 위하여 X 대역(7.9~8.4 GHz)에서 동작하는 MDAS 시제품을 제작하였으며, 설계 변수들은 설계 경험을 바탕으로 실험적으로 최적화하였다. 실험 결과는 교차 다이폴 소자에 의한 MDAS가 최소한 6.1 % 대역폭내에서 $\pm$20$^{\circ}$의 양호한 구형 빔 패턴을 형성함을 보여주었다.

• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.477-480
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• 2002

A new microporous TiO2-pillared layered titanate has been successfully prepared by hybridizing the exfoliated titanate with the anatase TiO2 nano-sol. According to the X-ray diffraction analysis and N2 adsorption-desorption isotherms, the TiO2-pillared layered titanate showed a pillar height of ~2 nm with a high surface area of ~460 m2/g and a pore size of ~0.95 nm, indicating that a microporous pillar structure is formed. Its photocatalytic activity was evaluated by measuring the photodegradation rate of 4-chlorophenol during irradiation of catalyst suspensions in an aqueous solution. An enhancement in activity of ca. 170% was obtained for TiO2-pillared layered titanate compared to that of the pristine compound such as layered cesium titanate.

• Macromolecular Research
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• 제11권2호
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• pp.110-114
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• 2003

When using the dipping method for crystal formation, mono-layered colloidal crystal structures depend upon the lift-up rate of a glass substrate. The mono-layered colloidal crystals showed the highest quality when the glass substrate was raised at a rate of 3 mm/min at 25 $^{\circ}C$ in a 1 wt% polystyrene colloidal suspension (ethanol medium). In addition, in order to obtain multiple-layered colloidal crystals, an external electric Held was introduced. Multiple-layered colloidal crystals were successfully obtained via this method. The colloidal particles were well ordered over large areas and assembled into a homogeneous structure.

• 한국세라믹학회지
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• 제48권5호
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• pp.396-403
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• 2011

In this study, we investigated the mechanical behaviors of layered thermal barrier coatings by indentations. Various single and double-layered thermal barrier coatings were deposited by air plasma spray process using different type of commercialized YSZ (Yttria stabilized zirconia) starting powders. Indentation stress-strain curve, load-displacement curve and hardness of the single and the double-layered thermal barrier coatings were obtained experimentally and analyzed. The indentation damages at the same loads were compared, and thus, the results depend on the structure of each coating. The result indicates improvement in damage resistances from tailoring of layered structures in the component of gas turbine system is expected.