• 한국세라믹학회지
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• 제55권5호
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• pp.446-451
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• 2018

In this study, different formulations of magnesium oxide and various modifiers (phosphoric acid, ferrous sulfate, pure acrylic emulsion, silicone acrylic emulsion, glass fiber, and polypropylene fiber) were used to prepare magnesium oxychloride cement composites. The compressive strength of the magnesium oxychloride cement was tested, and the softening coefficients of the composites after soaking in water were also calculated. The results showed that a magnesium oxychloride cement sample could not be coagulated when the MgO activity was 24.3%, but the coagulation effect of the magnesium oxide cement sample was excellent when the MgO activity was 69.5%. While pure acrylic emulsion, silicon-acrylic emulsion, and glass fiber showed insignificant modification effects on the magnesium oxychloride cement, ferrous sulfate heptahydrate, phosphoric acid, and polypropylene fiber could effectively improve its water resistance and compressive strength. When the phosphoric acid, ferrous sulfate heptahydrate, and polypropylene fiber contents were 0.47%, 0.73%, and 0.25%, respectively, the softening coefficient of a composite soaked in water reached 0.93 after 7 days, and the compressive strength reached 64.3 MPa.

• E2M - 전기 전자와 첨단 소재
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• 제11권10호
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• pp.24-31
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• 1998

Interfacial effect in polymetric composites have been studied extensively. This report deals mainly with the effects of interfacial space charge and interface structure. A model for the dynamic process of interfacial space charge accumulation is proposed. The new model might interpret some interface phenomena which is difficult to be explained in terms of traditional Maxwell-Wagner theory. An interface structure is also presented, by which the importance of surface treatment of glass Fiber for improving the properties of FRP could be well understood.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.27-30
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• 2003

In order to apply fracture detection we fabricated the CP-FRP using carbon-powder and analyzed conductive mechanism of it. The composites showed lower initial resistance as the carbon powder and amount of glass fiber(TEX) was used much more. When those are compared with each other that before and after bending test, the more cracks observed in matrix after bending test. We become to know that the conductivity of the composites depends on percolation structure of carbon powder.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1757-1764
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• 1997

The geometric and elastic models based on the unit cell have been proposed to predict the geometric characteristics and the engineering constants of plain and satin woven composites. In the geometric model, length and inclined angle of the yarn crimp and the fiber volume fraction of woven composites have been predicted. In the elastic model, the coordinate transformation has been utilized to transform the elastic constants of the yarn crimp to those of woven composites, and the effective elastic constants have been determined from the volume averaging of the constituent materials. Good correlations between the model predictions and the experimental results of carbon/epoxy and glass/epoxy woven composites have been observed. Based on the model, the effect of various geometric parameters and materials on the three-dimensional elastic properties of woven composites can be identified.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.371-374
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• 2005

The research reported in this paper provides the test results of eleven reinforced concrete beams strengthened with FRP composites. Three parameters were considered in this investigation: the amount of FRP composites, the types of bonding schemes(continuous sheets or strips), and the material types of FRP composites (Carbon or Glass). The experimental results indicated that because the rupture strain of FRP composites was relatively higher that the yield strain of steel bars, the RC beams strengthened with FRP composites failed due to concrete crushing before the FRP composites arrived at its rupture strain. The compatibility-aided truss model showed reasonable agreement between the predicted and experimental shear stress-strain curves of the beams throughout the entire loading history.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.95-98
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• 2005

This paper proposes the solutions predicting the coefficient of the thermal expansion changes of composites which include the fiber-like shaped ($a_1$ > ($a_2$ = ($a_3$) and the disk-like shaped (al = a2> a3) inclusions like two dimensional geometries, which has one aspect ratios, ${\alpha}$ = ($a_1$ /($a_3$). The analysis follows the procedure developed for elastic moduli by using the generalized approach of Eshelby’s equivalent tensor. The influences of the aspect ratios, on the effective coefficient of thermal expansion of composites containing aligned isotropic inclusions are examined. This model should be limited to analyze the composites with unidirectionally aligned inclusions and with complete binding to each other of both matrix and inclusions having homogeneous properties. The coefficient of thermal expansion of composites (${\theta}_{11}$,${\theta}_{22}$and ${\theta}_{33}$) are investigated. From material data of the composites with glass fiber in epoxy resin, the thermal expansions along the aspect ratio were obtained and similar to the Chow model. The longitudinal coefficients of thermal expansion ${\theta}_{11}$decrease, as the aspect ratios increase. However, the transverse coefficients of thermal expansion ${\theta}_{22}$increase or decrease, as the aspect ratios increase. And both of them decrease, as the concentration increases.

• Elastomers and Composites
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• 제54권2호
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• pp.135-141
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• 2019

Polyphenylene sulfide (PPS) was filled with glass fiber (GF), aramid fiber (AF), and solid lubricants to improve the mechanical properties and wear resistance. The addition of GF effectively enhanced the tensile strength, flexural modulus, and impact strength of PPS, while solid lubricants such as polytetrafluoroethylene (PTFE), molybdenum disulfide ($MoS_2$), and tungsten disulfide ($WS_2$) lowered the friction coefficients of the composites to below 0.3. The ball nut and motor pulley of the electric power steering (EPS) were manufactured using the PPS composites, and feasibility was ascertained thereafter by conducting the durability test. The composites filled with GF and AF showed high mechanical strength, but slip occurred at the interface between the pulley and belt while testing above $50^{\circ}C$. When small amounts of lubricants were added, the slip was no longer detected because of the suppression of friction heat. It is realized that the low friction as well as high mechanical properties is important to ensure the reliability of plastic pulleys.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.894-899
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• 2012

폐 전자제품의 양이 지속적으로 증가하므로 폐 인쇄회로기판(WPCBs: waste printed circuit boards)의 재활용에서 금속과 유리섬유 및 에폭시 수지를 분리하는 방법에 대한 연구가 필요하다. 본 연구에서는 WPCBs로부터 금속과 유리섬유 및 에폭시 수지를 분리하기위해 dimethylformamide 용매와 어트리션 밀 반응기를 사용하였다. WPCBs에서 유리섬유의 분리는 다양한 교반기를 이용하여 교반속도를 300~600 rpm에서 반응시간을 1~2 h에서 반응을 수행하였다. WPCBs에서 에폭시 수지의 분리도를 재생 유리섬유의 열 중량 분석을 통해 분석하였으며 기계화학적 방법인 어트리션밀 교반기에서 에폭시 수지의 분리도가 증가하였다. 재생 유리섬유를 보강재로 재활용하기 위하여 재생 유리섬유/불포화 폴리에스테르 수지 복합재료로 적용하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.167-170
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• 2004

In order to investigate the impact behaviors of 3-D braided glass/epoxy composites, the energy profiles and damage area were compared to the laminates of similar volume fraction and composition. The energy profiles showed different characteristics from each other which indicates they have distict energy absorption mechanisms. The image analysis on the damage projections visualized the crack propagation paths along the fiber direction.

• Composites Research
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• 제26권4호
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• pp.245-253
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• 2013

본 연구에서는 입자형태인 두 가지 이상의 강화제가 기지 내에 무작위로 분포하여 하이브리드 복합재료를 이룰 때, 강화제의 함유량에 따른 복합재료의 인장강도 및 탄성계수를 예측할 수 있는 이론 모델을 제안하였다. 이를 위하여 연속적인 두 강화제가 기지 내에 평행하게 분포한 복합재료 모델에 입자형태의 한 가지 강화제가 무작위하게 분포한 복합재료 모델을 수정 적용하였다. 본 연구에서 제안한 모델의 정확성과 타당성을 논의하기 위해, 산업체에서 널리 쓰이고 있는 폴리프로필렌을 기지로 하고, 탈크와 유리단섬유를 서로 다른 강화제로 한 복합재료를 제작하여 인장강도 및 탄성계수를 측정하였다. 인장강도 값을 예측하는 경우, 이전의 이론 모델이 실험 측정값과 7배 이상의 오차를 보이는 반면 본 연구의 모델은 비슷한 값을 예측하였다. 탄성계수의 경우에도 본 연구의 모델은 비교적 정확하게 실험 측정 값을 예측할 수 있었다.