• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.61-63
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• 2001

Residual stress distribution in injection-molded short fiber composites was determined using layer-removal method. Polysterene with 3 vol% carbon fibers was injection-molded into the tensile specimen. With milling machine layer-removal process was conducted and the curvature data were acquired. Treuting and Read analysis which is assuming isotropic material, and White analysis considering anisotropy due to the fiber orientation were used to calculate residual stress of the flow direction through the thickness direction and compared with each other.

• Carbon letters
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• 제9권2호
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• pp.127-130
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• 2008

This study aims to find a correlation between XRD and Raman result of the activated carbon fibers as a function of its activation degrees. La of the isotropic carbon fiber prepared by oxidation in carbon dioxide gas have been observed using laser Raman spectroscopy. The basic structural parameters of the fibers were evaluated by XRD as well, and compared with Raman result. The La of the carbon fibers were measured to be 25.5 ${\AA}$ from Raman analysis and 23.6 ${\AA}$ from XRD analysis. La of the ACFs were 23.6 ${\AA}$ and 20.4 ${\AA}$, respectively, representing less ordered through activation process. It seems that the $I_D/I_G$ of Raman spectra were related to crystallite size(La). Raman spectroscopy has demonstrated its unique ability to detect structural changes during the activation of the fibers. There was good correlation between the La value obtained from Raman and XRD.

• Carbon letters
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• 제3권3호
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• pp.146-151
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• 2002

Activated carbon fibers were prepared from the petroleum isotropic pitch and organometallic compounds. The metalsvwere dispersed uniformly in the ACFs. The specific surface area and pore size distributions of metal containing ACFsvwere measured. The mesopores of ACFs were developed by Co, Ni, and Mn metals addition and the catalytic reactivityvof ACFs'SOx removal was increased by adding Ni and Pd metals. It was found that the mesopores did not work forvthe improvement of catalytic reactivity of ACFs' SOx removal with the blank experiment using the metal removedvACFs.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1165-1171
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• 2004

The free vibration analyses of the isotropic and CFRP laminated composite rectangular plates with point supports at the fix edge is performed by FEM. We showed optimal position and mode shape of point supports that maximized fundamental natural frequency of the isotropic and CFRP laminated composite rectangular plates by each aspect ratio and the number of point supports.

• 한국재료학회지
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• 제13권11호
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• pp.749-755
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• 2003

A development of micropores of $CO_2$activated isotropic carbon fibers from TEM was observed. It was observed that the micropores of activated carbon fibers(ACFs) were consisted of slit-shaped pores(SP) and cylinder-shaped pores(CP). The SPs were formed between two parallel-carbon layers, and the CPs were formed at a place which is connected polygonally by more than two carbon layers. It was shown that the CPs of the ACFs were developed at high degree of burn-offs and at high activation temperature. The pore size distribution of the best ACF, which was observed at a highest value of specific surface area(3,495 $\m^2$/g), showed a continuous distribution in the range of about $4∼l5\AA$, and the median pore size was 6.7$\AA$. The super-high specific surface area of ACFs was found to be due to that the SPs were connected with a maximum size of 7∼8$\AA$ continuously, It is possible that the SPs should be formed in the ACFs in order to show super-high SSA.

• 한국재료학회지
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• 제7권2호
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• pp.121-128
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• 1997

이방성과 등방성을 갖는 두 종류의 피치계 탄소섬유를 TGA장치를 이용하여 $CO_{2}$gas와 공기중에서 등온산화반응을 실시하였다. $CO_{2}$ gas보다 공기중에서의 산화가 훨씬 빠르게 일어났으며, $600^{\circ}C$공기중에서 등방성 T-10IS섬유는 이방성 HM-60섬유보다 23.9배나 빠른 산화속도를 보였다. 실험적으로 구한 활성화에너지를 저온에서 36-56Kcal/mole의 값을 가지며, 고온에서는 6-13Kcal/mole의 값을 나타내었다. 반응기구(zone 1,2,3)의 천이도는 T-10IS섬유보다 HM-60 섬유가 높았으며, 공기중에서보다 $CO_{2}$ gas분위기에서 더 높게 나타났다. SEM으로 관찰된 표면상변화로부터 탄소섬유의 산화반응은 섬유의 결함을 따라 진행된다는 것을 알 수 있었다.

• Carbon letters
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• 제15권4호
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• pp.247-254
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• 2014

In this work, thermal treatment accompanied with different acid treatments was applied to a commercial coal tar pitch (CTP) to obtain a spinnable precursor pitch for carbon fiber. In the case of thermal treatment only, a relatively high reaction temperature of between $380^{\circ}C$ and $400^{\circ}C$ was required to obtain a softening point (SP) range of $220^{\circ}C-260^{\circ}C$ and many meso-phase particles were created during the application of high reaction temperature. When nitric acid or sulfuric acid treatment was conducted before the thermal treatment, the precursor pitch with a proper SP range could be obtained at reaction temperatures of $280^{\circ}C-300^{\circ}C$, which were about $100^{\circ}C$ lower than those for the case of thermal treatment only. With the acid treatments, the yield and SP of the precursor pitch increased dramatically and the formation of meso-phase was suppressed due to the lower reaction temperatures. Since the precursor pitches with acid and thermal treatment were not spinnable due to the inhomogeneity of properties such as molecular weight distribution and viscosity, the CTP was mixed with ethanol before the consecutive nitric acid and thermal treatments. The precursor pitches with ethanol, nitric acid, and thermal treatments were easily spinnable, and their spinning and carbon fiber properties were compared to those of air blowing and thermal treated CTP.

• Carbon letters
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• 제1권1호
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• pp.6-11
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• 2000

Coal tar pitch was chemically modified with 10 wt% benzoquinone (BQ) to raise the softening point of isotropic pitch precursor and the precursor was melt-spun into pitch fibers, stabilized, carbonized and activated with steam at $900^{\circ}C$. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area. Those adsorption isotherms fitted into 'Type I' according to Brunauer, Deming, Deming and Teller classification. However, there was very thin low-pressure hysteresis that lower closure points of the hysteresis are about 0.42-0.45. From the pore size distribution curves, there might be some micropores having narrow-necked bottle; a series of interconnected pore is more likely than discrete bottles. FT-IR studies showed that the functional groups such as carboxyl, quinone, and phenol were introduced to ACFs-BQ surface after steam activation. Methylene blue decolorization and iodine adsorption capacity of ACF-BQ increased linearly with the increase of specific surface area and was larger than that of ACF-Kureha at the same specific surface area.

• 한국안전학회지
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• 제12권2호
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• pp.27-36
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• 1997

This paper evaluates the static and fatigue bending strengths of CFRP (carbon fiber reinforced plastic) laminates subjected to hygrothermals. The specimens which had different stacking composition, orthotropic and quasi-isotropic laminated plates, were prepared for this experiment. A steel ball launched by the air gun collides against CFRP laminates to generate impact damages, and the 3-point fatigue bending test is carried out by using the impacted laminates to investigate the influence of hygrothermals on the effect on the residual bending fatigue strength of CFRP laminates.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1533-1538
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• 2008

The development of new material systems like Carbon Fiber Reinforced Polymer (CFRP) places ever higher demands on the techniques for non-destructive material characterisation. Image-producing eddy current methods also need to satisfy these demands. Eddy-current imaging of FRP is based on the anisotropic electrical properties of the material investigated. Significant differences in conductivity between carbon fibres, polymer matrix and integrated functional components can be found. The availability of high-resolution sensors enables access to the local distribution of the electromagnetic properties. The static and dynamic procedures for isolating influential characteristics, already in use in eddy-current technology, can now be supplemented by topographical images. The precondition for a successful implementation of the eddy-current procedure is a deeper understanding of the image-generating process which allows correct interpretation of the images obtained.