• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
• /
• pp.785-792
• /
• 2000

Repair and retrofit system of concrete structures has been developed from conventional reinforced concrete overlaying, steel plate bonding and recently to fiber composite systems. Research and study on carbon, aramid, and glass fiber composite system has been actively carried out from all over the world Glass fiber composite is proved to be competitive technically and enconomically, among fiber composite system. CAF system is a system developed locally using all domestic materal, glass fabric and epoxy, and improved in shear bonding property by utilizing silica fume mixed with epoxy. All the tests on material properties, structural behavior, constructiveness at site and quality control procedure proved to be most appropriate system so far developed. Futher research work is and will be under progress for utilization of this system which will be applied to more adverse situation.

• 대한금속재료학회지
• /
• 제50권10호
• /
• pp.729-734
• /
• 2012

This study investigated the effect of water absorption on the tensile properties of carbon-glass/epoxy hybrid composites at room temperature and $-30^{\circ}C$. To investigate the effect of the position of glass fabric in the hybrid composite on the tensile properties, the stacking pattern of the fiber fabrics for reinforcing was created in three different ways: (a) glass fabrics sandwiched between carbon fabrics, (b) carbon fabrics sandwiched between glass fabrics and (c) alternative layers of carbon and glass fabrics. They were manufactured by a vacuum-assisted resin transfer molding (VARTM) process. The results showed that there was surprisingly little difference in tensile strength at the two different temperatures with dry and wet conditions. However, the water absorption into the hybrid system affected the tensile properties of the hybrid composites at RT and $-30^{\circ}C$. When the glass fabrics were at the outermost layers, the hybrid composite had the lowest tensile properties. This is attributed to the fact that the composite had a relatively high water absorption rate.

• 한국생산제조학회지
• /
• 제26권4호
• /
• pp.395-401
• /
• 2017

Energy absorption capabilities and failure modes of circular tubes made of glass/epoxy with two trigger mechanisms were evaluated. Three types of glass/epoxy tubes were fabricated using a hand lay-up method with unidirectional and woven fabric prepregs tapes, and a filament winding method. The one end of the fabricated tubes was machined for the bevel trigger and tulip trigger. Then, crush tests were conducted at 10 mm/min loading speed, wherein the glass/epoxy tubes were crushed by a brittle fracturing mode combined with fragmentation and lamina-splaying modes. The UD glass/epoxy tubes with a bevel trigger and the filament winded tubes with a tulip trigger showed the maximum and minimum specific energy absorptions, respectively, with a difference of 9.3%. The tube with a tulip trigger exhibited a maximum reduction of 5.7% in the initial peak load; the tube with a bevel trigger showed a maximum increase of 2.9% in the specific energy absorption.

• Composites Research
• /
• 제15권2호
• /
• pp.1-10
• /
• 2002

본 논문에서는 특성길이 방법과 실험을 통하여 핀하중을 받는 평직 유리/에폭시 적층판 체결부의 강도를 평가하였다. 특성길이 및 강도에 영향을 미치는 인자들의 효과를 연구하기 위해, 핀과 원공이 접하는 부분에 코사인 하중을 가할 경우와, 적절한 변위경계조건으로 처리할 경우, 접촉요소를 사용하여 비선형 해석을 수행하는 경우 등 총 세가지 방법으로 특성길이 및 강도를 계산하였다. 또한 체결부의 강도는 사용하는 파손식의 영향을 받게 되므로 Tsai-Wu 파손식과 Yamada-Sun 파손식을 사용하여 결과를 비교하였다. 평직으로 이루어진 적층판과 일방향 프리프레그로 이루어진 적층판 모두에서 접촉요소를 사용한 비선형 해석이 시험과 가장 일치하는 결과를 나타내었다. 일방향 프리프레그만을 사용한 적픙판 체결부에서와 달리 모든 층이 평직으로 이루어진 유리/에폭시 채결부의 경우 Tsai-Wu 파손식을 사용한 결과가 실험값과 더 잘 일치함을 알 수 있었다.

• 한국항공운항학회지
• /
• 제13권1호
• /
• pp.43-49
• /
• 2005

There are several ways to mold the complex material, and it is divided to vacuum pack mold, compression mold, and hand lay up for a high molecular substance as a basic material. Moreover, it can be divided to general manufacturing (Single form) and mold manufacturing(Mold form) under normal temperature for Firefly. Firefly was manufactured with hand lay up and general manufacturing that using the foam core, glass fabric, and template without mold. However, mold manufacturing that is producing the surface by semi-sandwich using thin foam core and glass fabric then reinforce the inside with spar and rib is on developing. Mold manufacturing can make easy to production, standardize the quality, and possible to mass producing. In this paper, we present the mold producing process for canard aircraft "Firefly", and the problems and solutions during producing Firefly. Moreover, it complements the defect that the problems caused by master manufacturing error when produce several masters of a large part, and make the manufacturing process to be shortened by the replacement from the supplementary plate to the foam that is installed when producing lay up mold.

• Nuclear Engineering and Technology
• /
• 제10권4호
• /
• pp.195-201
• /
• 1978

감마선을 이용하여 폴리에스터직포에 methacylic acid와 methyl methacylate를 graft 종합반응시켜서 그 반응성을 보았다. 폴리에스터직포에 acrylic acid, methacrylic acid, methyl methacrylate를 중합반응 시켰을 때 graft 효율은 monomer 혼합용액내에 포함되어 있는 용매의 dielectric constant에 따라 상당한 차이를 나타내었다. Graft 수율은 방사선 선량과 monomer 농도 및 swelling agent의 농도에 좌우되었다. MA graft copolymer의 glass transition temperature (101$^{\circ}C$)와 melting point (238$^{\circ}C$)를 측정하였고, 정전기 효과는 frictional electricity 8,000V에서 half life가 0 sec이었으며, moisture regain는 5.6%, wicking time은 1 sec이었다.

• Composites Research
• /
• 제16권2호
• /
• pp.48-53
• /
• 2003

본 논문에서는 카본 블랙의 함유율에 따른 유리섬유/에폭시 직조 복합재료 적층판의 유전율에 대한 실험 및 예측방법에 대한 연구를 수행하였다. 유전율 측정은 5 GHz∼18 GHz의 주파수 영역에서 수행하였으며, 복합재료의 유전율은 카본 블랙의 함유율과 주파수의 함수로 얻을 수 있었다. 카본 블랙의 함유율에 따른 복합재료의 유전율을 모사하는 혼합법칙을 얻기 위한 새로운 방법이 제시되었으며. 이 방법에서는 실험적으로 얻기 어려운 카본 블랙 자체의 유전율도 얻을 수 있다. 혼합법칙으로 계산된 복합재료 유전율 결과는 실험적으로 얻은 유전율을 비교적 잘 모사하는 결과를 얻을 수 있었다.

• International Journal of Railway
• /
• 제1권3호
• /
• pp.113-116
• /
• 2008

The long-tenn exposure of polymeric composite materials to extreme-use environments, such as pressure, temperature, moisture, and load cycles, results in changes in the original properties of the material. In this study, the effect of combined environmental factors such as ultraviolet ray, high temperature and high moisture on mechanical and thermal analysis properties of glass fabric and phenolic composites are evaluated through a 2.5 KW accelerated environmental aging tester. The environmental factors such as temperature, moisture and ultraviolet ray applied of specimens. A xenon-arc lamp is utilized for ultraviolet light and exposure time of up to 3000 hours are applied. Several types of specimens - tensile, bending, and shear specimens that are warp direction and fill direction are used to investigate the effects of environmental factors on mechanical properties of the composites. Mechanical degradations for tensile, bending and shear properties are evaluated through a Universal Testing Machine (UTM). Also, storage shear modulus, loss shear modulus and tan a are measured as a function of exposure time through a Dynamic Mechanical Analyzer (DMA). From the experimental results, changes in material properties of glass fabric and phenolic composites are shown to be slightly degraded due to combined environmental effects.

• 한국건축시공학회지
• /
• 제16권6호
• /
• pp.545-551
• /
• 2016

막구조 건축물의 시공 증가에도 불구하고 국내에는 내화 및 방화기준이 마련되어있지 않고 일반 건축물의 내화기준을 적용하고 있어 막구조 건축물과 막재료의 특성을 반영하지 못하고 있다. 또한 막구조 건축물의 내화 및 방염성능을 확보하기 위해서는 막재료가 규정된 난연성능을 만족해야 한다. 따라서 본 연구에서는 건축용 막재의 고온에서의 안전성을 확보하기 위해 현무암섬유를 직포로 적용하였다. 그리고 막재의 강도특성과 방염 및 난연특성을 기존의 건축용 막재와 비교, 평가함으로써 막재료의 평가기준에 대한 참고자료로 삼고자 한다. 연구결과, 현무암섬유와 유리섬유 기반의 건축용 막재는 낮은 열방출율과 총방출열량을 나타내 화재안전성이 높은 것으로 확인되었다.

• 한국의류학회지
• /
• 제41권2호
• /
• pp.352-361
• /
• 2017

This study prepared 5 retroreflective fabrics of glass beads and colors of silver, gold and purple in order to characterize morphologies, luminance and illuminance properties. Retroreflective fabrics were prepared according to division and area by Samp.1 (Division 2, area $80cm^2$), Samp.2 (Division 2, area $60cm^2$), Samp.3(Division 3, area $60cm^2$), Samp.4 (Division 5, area $50cm^2$), and Samp.5 (Division 1, area $100cm^2$). The results of the morphologies indicate that the back side of retroreflective fabrics was the 3M-Sv, RF-Sv. The RF-Gd of the fabrics were woven fabrics and the SRF-Sv, SRF-Pp was knitting. The largest glass bead size was 3M-Sv and the smallest was SRF-Pp. RF-Sv was the thinnest and SRF-Sv, SRF-Pp were the thickest. The results of luminance properties indicated a tendency to decrease slightly as the number of divisions and area increased, except for Samp.2 to Samp.3. The result of illuminance properties tend to increase as the number of LED becomes greater than the number of divisions in the same area; in addition, the higher the luminance as a whole increases. The results show that it is preferable to use a silver-colored RF-Sv which has the highest luminance and physical properties when a retroreflective fabric is applied to clothes.