• Advances in Computational Design
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• 제7권3호
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• pp.253-279
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• 2022

This study investigated and predicted the Marshall stability of glass-fiber asphalt mix, carbon-fiber asphalt mix and glass-carbon-fiber asphalt (hybrid) mix by using machine learning techniques such as Artificial Neural Network (ANN), Support Vector Machine (SVM) and Random Forest(RF), The data was obtained from the experiments and the research articles. Assessment of results indicated that performance of the Artificial Neural Network (ANN) based model outperformed applied models in training and testing datasets with values of indices as; coefficient of correlation (CC) 0.8492 and 0.8234, mean absolute error (MAE) 2.0999 and 2.5408, root mean squared error (RMSE) 2.8541 and 3.3165, relative absolute error (RAE) 48.16% and 54.05%, relative squared error (RRSE) 53.14% and 57.39%, Willmott's index (WI) 0.7490 and 0.7011, Scattering index (SI) 0.4134 and 0.3702 and BIAS 0.3020 and 0.4300 for both training and testing stages respectively. The Taylor diagram also confirms that the ANN-based model outperforms the other models. Results of sensitivity analysis show that Carbon fiber has a major influence in predicting the Marshall stability. However, the carbon fiber (CF) followed by glass-carbon fiber (50GF:50CF) and the optimal combination CF + (50GF:50CF) are found to be most sensitive in predicting the Marshall stability of fibrous asphalt concrete.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.492-501
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• 2012

In this paper, the status of the recent applications of carbon fiber was investigated through the published papers, informations or data of the internet etc. The production cost of the carbon fiber will be lowered and in the other hand the quality would be upgraded. Therefore in the automobile area, the use of the carbon fiber will be increased, specially for the high quality cars and the sports cars. Also the structures, wings and many secondary parts of the commercial airplanes will be made of carbon fibers more and more. The carbon fiber applications are extended to many fields including ship buildings like as boats, canoes and retrofitting in civil engineering, sporting goods, instruments etc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1322-1325
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• 2005

The main objectives of this research work are to develop conductive glass fiber woven roving and carbon fiber unidirectional fabric composite materials and to determine their electromagnetic shielding effectiveness(EMSE). Epoxy is the matrix phase and glass, carbon fiber are the reinforcement phase of the composite material. Carbon black are incorporated as conductive fillers to provide the electromagnetic shielding properties of the composite material. The amount of carbon black in the composite material is varied by changing the carbon black composition, woven roving and unidirectional (fabric) structure. The EMSE of various fabric composites is measured in the frequency range from 300MHz to 800MHz. The variations of EMSE of woven roving and unidirectional composites with fabric structure, metal powder composite are described. Suitability of conductive fabric composites for electromagnetic shielding applications is also discussed.

• 대한기계학회논문집A
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• 제31권4호
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• pp.417-424
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• 2007

This paper reports fabrication and characterization of a pressure sensor using a pitch-based carbon fiber. Pitch-based carbon fibers have been shown to exhibit the piezoresistive effect, in which the electric resistance of the carbon fiber changes under mechanical deformation. The main structure of pressure sensors was built by performing backside etching on a SOI wafer and creating a suspended square membrane on the front side. An AC electric field which causes dielectrophoresis was used for the alignment and deposition of a carbon fiber across the microscale gap between two electrodes on the membrane. The fabricated pressure sensors were tested by applying static pressure to the membrane and measuring the resistance change of the carbon fiber. The resistance change of carbon fibers clearly shows linear response to the applied pressure and the calculated sensitivities of pressure sensors are $0.25{\sim}0.35 and 61.8 ${\Omega}/k{\Omega}{\cdot}bar$ for thicker and thinner membrane, respectively. All these observations demonstrated the possibilities of carbon fiber-based pressure sensors.

• 방사선산업학회지
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• 제9권1호
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• pp.15-20
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• 2015

Carbon fiber has received much attention owing to its properties, including a large surface-to-volume ratio, chemical and thermal stability, high thermal and electrical conductivity, and high mechanical strengths. In particular, magnetic nanopowder dispersed carbon fiber has been attractive in technological applications such as the electrochemical capacitor and electromagnetic wave shielding. In this study, the nickel-oxide-nanoparticle dispersed polyacrylonitrile (PAN) fibers were prepared through an electrospinning method. Electron beam irradiation was carried out with a 2.5 MeV beam energy to stabilize the materials. The samples were then heat-treated for stabilization and carbonization. The nanofiber surface was analyzed using a field emission scanning electron microscope (FE-SEM). The crystal structures of the carbon matrix and nickel nanopowders were analysed using X-ray diffraction (XRD). In addition, the magnetic and electrical properties were analyzed using a vibrating sample magnetometer (VSM) and 4 point probe. As the irradiation dose increases, the density of the carbon fiber was increased. In addition, the electrical properties of the carbon fiber improved through electron beam irradiation. This is because the amorphous region of the carbon fiber decreases. This electron beam effect of PAN fibers containing nickel nanoparticles confirmed their potential as a high performance carbon material for various applications.

• Composites Research
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• 제28권5호
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• pp.311-315
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• 2015

섬유체적비에 따라 복합재료의 기계적 열적 특성이 크게 달라지기 때문에, 복합재료 설계시 섬유체적비를 올바르게 측정하는 것이 매우 중요하다. 일반적으로 섬유체적비를 측정하는 여러 방법은 산화되지 않는 유리섬유나 세라믹섬유를 사용한 복합재료의 경우에는 적합하고 효율적이다. 하지만 산화현상이 있는 탄소섬유의 경우에는 산화 방법과 조건에 따라서 다른 결과를 가져오게 되며 그러므로 올바른 섬유체적비를 측정이 어렵다. 본 연구에서는 Thermogravimetric analysis를 수행하여 산화되는 탄소섬유의 질량 감소량을 보정하여 탄소섬유 복합재료의 섬유체적비를 측정하였고 현미경 단면 이미지를 이용하여 그 결과를 검증하였다.

• 대한치과보철학회지
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• 제38권5호
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• pp.640-649
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• 2000

In the restoration of endodontically treated teeth, carbon fiber post was recently introduced. The purpose of this in vitro study was to investigate the fracture strength of teeth restored with a pre-fabricated carbon fiber post in comparison with teeth restored with a prefabricated titanium post & custom cast gold post after cyclic loading in the different environment. A total of 30 recently extracted human central incisors of similar dimension with crowns removed were used. All teeth were placed into acrylic blocks and every steps for post and core fabrication were made accord-ing to manufacture's instruction. The post length and core dimensions were standardizd. All teeth were divided into 6 groups: 1) carbon fiber post / atmosphere, 2) titanium post / atmosphere, 3) gold post / atmosphere, 4) carbon fiber post / wet, 5) titanium post / wet, 6) gold post / wet. Carbon fiber post and titanium post were cemented in place using resin cement and cores were fabricated with Ti-Core. Custom cast gold post was made from Duralay pattern resin and cemented using resin cement, too. All specimens were thermocycled 10,000 times. After 50,000 cyclic loading, failure strength was measured using Instron testing machine. Kruskal-Wallis test followed by Mann-Whitney test was used to compare the mean fracture strength. Results were as follows : 1. All specimens showed lower fracture strength in wet environment after cyclic loading than in atmosphere condition, but did not reveal a significant difference. 2. There was no significant difference between carbon fiber post specimen and titanium post specimen in the same environment. 3. Gold cast post specimen showed significant different greater fracture strength than those of others in the same environment. 4. Carbon fiber post specimen showed no root fracture.

• Carbon letters
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• 제6권4호
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• pp.234-242
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• 2005

Bending and tensile properties of 2D cross-ply C/C composites with processing heat treatment temperature (HTT) are evaluated. C/C composites used are made from two types of PAN based T700 and M40 carbon fibers with phenolic resin as carbon matrix precursor. Both the types of composites are heat treated at different temperatures (ranging from 750 to $2800^{\circ}C$) and characterized for bending and tensile properties. It is observed that, real density and open porosity increases with HTT, however, bulk density does show remarkable change. The real density and open porosity are higher in case T-700 carbon fiber composites at $2800^{\circ}C$, even though the density of M40 carbon fiber is higher. Bending strength is considerably greater than tensile strength through out the processing HTT due to the different mode of fracture. The bending and tensile strength decreases in both composites on $1000^{\circ}C$ which attributed to decrease in bulk density, thereafter with increase in HTT, bending and tensile strength increases. The maximum strength is in T700 fiber based composites at HTT $1500^{\circ}C$ and in M40 fiber based composites at HTT $2500^{\circ}C$. After attending the maximum value of strength in both types of composite at deflection HTT, after that strength decreases continuously. Decrease in strength is due to the degradation of fiber properties and in-situ fiber damages in the composite. The maximum carbon fiber strength realization in C/C composites is possible at a temperature that is same of fiber HTT. It has been found first time that the bending strength more or less 1.55 times higher in T700 fiber composites and in M40 fiber composites bending strength is 1.2 times higher than that of tensile strength of C/C composites.

• 한국산학기술학회논문지
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• 제17권5호
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• pp.80-85
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• 2016

탄소섬유강화 복합재는 기계적 물성이 우수하여 다양한 산업분야에서 활용되고 있으나 섬유길이가 짧은 단섬유 형태로 함침 되고 있어 강도와 강성을 증대시키는데 한계가 있다. 이를 보완하기 위한 LFT-D성형은 탄소 또는 유리섬유를 열가소성 수지와 혼합하여 압출 후 프레스 성형하여 제품을 만드는 공법으로 연속공정이 가능하고 사출성형에 비해 생산성이 높아 자동차 구조용 부품을 제작하는데 사용할 수 있다. 본 연구에서는 LFT-D공법으로 성형된 탄소 장섬유강화 열가소성 복합소재의 기계적 특성을 파악하기 위하여 탄소 장섬유의 함침과 압출공정을 수행할 수 있는 Lab scale의 소형 압출기 시스템을 제작하였다. Lab scale의 소형 압출기를 사용하여 제작된 탄소 장섬유 복합소재를 프레스 성형하여 시편을 제작하고 재료의 기계적 특성을 평가한 결과, 탄소섬유길이, 프레스 가압압력 및 탄소섬유 함유량이 복합소재의 강도 및 강성의 증가에 영향을 미침을 알 수 있었다. 향후 탄소 장섬유 복합소재의 기계적 성질 향상을 위해서 혼합 스크류 설계, 탄소 섬유코팅 등에 대한 추가적인 연구가 필요하다.

• 한국건설순환자원학회논문집
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• 제8권4호
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• pp.429-435
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• 2020

본 연구에서는 탄소계 섬유를 이용하여 EMP차페 시멘트 개발을 위해 저 직경 카본섬유 사용량에 따른 시멘트 페이스트의 물리적 특성과 EMP차폐 성능평가를 실시하였다. 사용된 저 직경 카본섬유의 길이는 100㎛의 크기로서 육안으로는 분말형태를 나타내기 때문에 시멘트 혼화재 개념으로 사용하였다. 실험결과 저 직경 카본섬유 시멘트 사용량 대비 5% 사용 하였을시 압축강도 및 EMP차폐에 효과가 있었으며 그 이상의 사용시에는 차폐효과는 증가 하지 않았다. 또한 실험체 두께에 따른 EMP차폐성능 검토 결과 저 직경 카본섬유가 사용되지 않은 Plain은 두께에 따른 차폐율 증가 효과가 없었으나 저 직경 카본섬유가 사용된 실험체들은 두께 증가에 따라 차폐성능이 증가 하였다. 따라서 저 직경 카본섬유 사용량과 실험체 두께에 따른 성능을 비교평가 하였을시 EMP차폐율 증가시키기 위해서는 저 직경 카본섬유 사용량은 5%가 최적이며 사용량을 증가시키는 것보다 두께를 증가시키는 방법이 효과적일 것으로 사료된다.