• Composites Research
• /
• 제27권6호
• /
• pp.236-241
• /
• 2014

본 연구에서는 공항 포장용 유지보수 재료로 사용되는 폴리머 콘크리트의 자외선 노출에 대한 기계적 물성 변화를 확인하기 위해 자외선 노출 전/후 시편의 압축강도 및 연성인자의 변화를 평가하였다. 현재 공항 포장용으로 사용되는 폴리머 콘크리트의 비율과 선행연구를 통해 얻은 최적 배합비율을 참고하여 시편을 제작하였다. 자외선 발생 램프의 출력을 고려하여 자연상태에서 노출되는 등가시간을 계산한 후 최대 3년에 해당하는 시간만큼의 등가시간 동안 시편을 노출시켰다. 실험결과, 자외선 노출 자체는 재료물성에 거의 영향을 주지 않았으며, 자외선 노출에 따른 온도상승에 의한 재료물성 변화가 주로 관찰되었다. 자외선에 의해 발생된 열에 노출된 후 모든 시편에서 인성은 감소하고, 압축강도는 증가하는 경향을 나타내었다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 추계학술대회 논문집
• /
• pp.265-266
• /
• 2010

• 한국전기전자재료학회논문지
• /
• 제24권7호
• /
• pp.547-553
• /
• 2011

We investigated the dielectric and mechanical properties of ceramic polymer composite xBNT - (1-x)LCP (x= 0, 10, 20, 30, 40 vol.%). The disk shaped BNT ($BaNd_2Ti_4O_{12}$) - LCP (liquid crystal polymer) composite samples were prepared by compression molding method. With increasing the BNT content in composites from 10 to 40 vol.%, the dielectric constant increased but the dielectric loss as well as bending strength of composites reduced. These composites were well described with modified Lichtenecker's model having k = 0.392 and 0.303 for the first and second ball milled BNT filled composites, which means that the BNT filler in composites are well dispersed. The dielectric constant of the composite comprised of the second milled BNT ($D_{50}$ = 1.39 um) was higher that of the composite of the first milled BNT ($D_{50}$= 2.45 um), which seems to be related with the different particle size and dispersion of BNT fillers in LCP matrix. The bending strength of the composite containing the second milled BNT was superior to that of the composite of the first milled BNT.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
• /
• pp.149-149
• /
• 2003

This paper presents the work peformed in a program developing composite material which properties satisfy structural and thermal requirements for aircrafts and spacecrafts. In the aerospace vehicle structures, the specific strength of the materials is one of the important requirements and this is why polymer matrix composite material with reinforced carbon fiber is widely used. However, the mechanical properties of the composite material have been known to be dependent on processing and this difficulties in evaluation have caused a lot of mechanical tests for each batch.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권10호
• /
• pp.1053-1059
• /
• 1996

The pulse-echo response of the piezoceramics PZT-polymer 3-3 type composite transducers with various PVA additions were investigated. The PZT powder was prepared by the molten salt synthesis method. The porous PZT specimens will be used as a filler to make 3-3 type comosite were prepared from a mixture of PZT and polyvinylalcohol(PVA) sphere by utilizing BURPS(Bumout Plastic Sphere) technique. It was shown that the transmitting and receiving sensitivity of 3-3 type piezoelectric composite transducers could be improved than that of solid PZT transducers. The reason is that 3-3 type piezoelectric composite have low dielectric constant, density and acoustic impedance. The distance between transducer and reflector was in good agreement with the distance calculated from the longitudinal velocity of the specimens and receiving time observed pulse-echo responses on the ultrasonic transducer analyzer.

• 한국전기전자재료학회논문지
• /
• 제26권5호
• /
• pp.360-366
• /
• 2013

For conventional electrical actuators, the materials are mainly made up of metals, which mean they are prone to corrosion and electrical sparking. Replacing these systems with polymer metal composite based materials can be solved both problems. Considering their excellent electromechanical property, low device fabrication cost, light weight, and good electrical conductivity, the actuator based on ionic polymer metal composite (IPMC) was fabricated using Nafion film, NaOH 0.1 molar solution, and Au electrode. IPMCs exhibit good electrostatic property which means they can in principle be used in making actuators based on electromechanical motions. The resistance measurements of Nafion film after soaking in NaOH and deionized water were demonstrated and compared each other. The result of sample soaked in NaOH showed better electrical conductivity than in deionized water. The fabricated IPMC actuator exhibits a large deformation of bending displacement of approximately 9 mm with applied low AC voltage 6.89 V at 2.84 Hz. The result of computer simulation was also very similar and shown as a bending displacement of 8.6085 mm.

• Transactions on Electrical and Electronic Materials
• /
• 제15권2호
• /
• pp.60-65
• /
• 2014

This article explains the experimental results of ferroelectric polarization switching (FPS) of potassium nitrate ($KNO_3$) with different polymers such as polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF) using simple melt-press techniques. To analyze the ferroelectric polarization switching in potassium nitrate ($KNO_3$) composite films at room temperature, we applied the Ishibashi and Takagi theory (based on Avrami model) to the switching current transient. To investigate the dimensionality of domain growth, the ferroelectric polarization switching current (FPS current) was observed from the square - wave bipolar signals across a resistance of $0.1k{\Omega}$ in series with the composite films. The existence of a switching current transient pulse confirmed the ferroelectricity and indicated the stability of the ferroelectric phase (phase III) of $KNO_3$ at room temperature. Polarization hysteresis (P-E) characteristics supported the prominent features of ferroelectric polarization switching in the composite films at room temperature.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.469-472
• /
• 2004

There have been numerous accelerated aging laboratory tests for evaluating suitability of polymeric materials and devices. Aging test for materials and its full scale device has been conducted, but poor correlation of aging test such as service experience were observed. Service experience plays a key role in the utility section of composite insulators. A meaningful and reliable accelerated aging test is needed for evaluating composite insulator. During the service these insulators are subjected to aging stress such as humidity, pollution, and electrical field, and erosion and tracking of the weathershed occurs. This paper presents the criteria of reliability evaluation and evaluation facilities for 22.9 kV suspension composite insulator. We adopt the criteria of reliability evaluation consist of two test methods. One is CEA tracking wheel test for examining the tracking and erosion performance of composite insulator. The other is multi-stress aging test for examining effects of environmental factors such as UV, temperature, humidity, etc on composite insulator.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 추계학술대회 논문집
• /
• pp.105-108
• /
• 1996

The positive active material for polymer film battery was prepared by using Polyphenylenediamine(PPD) synthesized in our lab. and 2.5-dimercapto-1, 3, 4-thiadiazole(DMcT) in various mixture ratio. The transference measurement of surface morphology and thermal stability of prepared composite film was carried out by using SEM and TGA, respectively. Electrocyhemical property and electrical conductivity of composite film were also measured by using cyclic voltammetry and four-probe method in dry box, respectively. The thermal stability of prepared composite film is more than 20$0^{\circ}C$. The electrical conductivity of composite film increased and showed the highest value(about 3 S/cm)when doped at 0.4% LiClO$_4$solution. And we could confirm that DMcT effect on reactiviation of PPD through cyclic voltammogram.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제52권3호
• /
• pp.144-151
• /
• 2003

IPMC(Ionic Polymer-Metal Composite) is promising candidate material for bio-related actuators mainly due to its biocompatibility and wet and soft properties. The widely used commercialized Nafion film has a few kinds of fixed thicknesses but more various film thicknesses are required for extensive applications. Especially for the enhanced force as an actuator, the thick film is essential. Various Nafion films with thickness of 0.4-1.2mm have been prepared by casting of liquid Nafion. Also, IPMC actuators using casted Nafion films have been fabricated and the basic mechanical properties such as stiffness, displacement and force were measured and analyzed. These results can be used for the optimized design of actuators for different applications.