• Carbon letters
• /
• 제1권1호
• /
• pp.12-16
• /
• 2000

Carbon fiber was reacted with gaseous silicon monoxide which is produced from pack-powder mixture at elevated temperature. As a result of the reaction, two kinds of SiC fiber were obtained. The first one was SiC fibers which were converted from carbon fiber. The fiber is constituted with polycrystal like fine grains or monolithic crystals that have a size from sub-micron to $10\;{\mu}m$. Their size depends on the temperature during the conversion reaction. The second one was ultra-fine SiC fibers that were found on the surface of the converted SiC fibers. The ultra-fine fibers have diameters from 0.08 to $0.2\;{\mu}m$ and their aspect ratio were larger than 100. The chemical composit ion of the ultra-fine fibers was analyzed using an Auger electron spectroscopy. In result, the fibers consist of 51% silicon, 38% carbon and 11% oxygen by weight.

• 대한환경공학회지
• /
• 제35권11호
• /
• pp.815-820
• /
• 2013

본 연구의 목적은 알루미늄판에 활성탄을 얇게 박판으로 코팅하여 분진제거를 위한 활성탄 전극을 제조함에 있다. 전극을 제조하기위하여 알루미늄판에 활성탄을 부착시키기 위한 적정 결합제 선정 그리고 결합제 사용에 따른 활성탄 세공의 막힘방지 그리고 제조된 제극의 분진제거능력 등을 알아보는 연구를 수행하였다. 알루미늄판에 활성탄 부착을 위한 결합제로는 비닐계의 PVA (polyvinyl acetate)가 적정하였고, 결합제 사용에 따른 활성탄 세공의 막힘을 방지하기 위해서는 우선 먼저 활성탄 세공에 결합제의 용매제를 충진하고 나중에 결합제와 활성탄을 혼합 후 고온에서 휘발시키는 방법이 적정하였다. 그리고 활성탄이 코팅된 전극판은 알루미늄 전극판보다 약 두배의 분진부착능력을 보여주었다.

• 한국전기전자재료학회논문지
• /
• 제21권11호
• /
• pp.973-976
• /
• 2008

In addition to its similarity to genuine diamond film, diamond-like carbon (DLC) film has many advantages, including its wide band gap and variable refractive index. In this study, DLC films were prepared by the RF PECVD (Plasma Enhanced Chemical Vapor Deposition) method on silicon substrates using methane ($CH_4$) and hydrogen ($H_2$) gas. We examined the effects of the RF power on the electrical properties of the DLC films. The films were deposited at several RF powers ranging from 50 to 175 W in steps of 25 W. The leakage current of DLC films increased at higher deposition RF power. And the resistivities of DLC films grown at 50 W and 175 W were $5\times10^{11}$ ${\Omega}cm$ and $2.68\times10^{10}$ ${\Omega}cm$, respectively.

• 한국재료학회지
• /
• 제13권11호
• /
• pp.732-736
• /
• 2003

A CP-GFRP(Carbon Powder-Glass Fiber Reinforced Plastic) sensor was fabricated for fracture detection. The electric resistance of the sensor was measured on condition of various composition of carbon powders and thickness of bundle of glass fibers. The resistance of the sensor was decreased as the increase of the content of carbon powders and the TEX of the glass fibers. In the case of loading on CP-GFRP, because inner crack was propagated, the part of percolation structures was disconnected. These observations show the following results. The conduction of CP-GFRP sensor is due to percolation structure of carbon powders and increase of resistance is due to expansion of cracks.

• 한국산학기술학회논문지
• /
• 제11권12호
• /
• pp.4685-4690
• /
• 2010

E-EGR Valve 고장의 원인이 되는 내부 퇴적물 축적을 최소화하기 위한 새로운 Valve 형상을 제안하고자 한다. 전산유체 해석을 통하여 다양한 형상에 대하여 유속과 유량을 관찰하였으며, 밸브 상부에 라운드를 추가한 Valve 디자인 변형을 통하여 유량손실 없이 Valve 내의 유속을 약 10% 향상시킬 수 있었다.

• Carbon letters
• /
• 제11권2호
• /
• pp.83-89
• /
• 2010

We prepared polycarbonate (PC)/poly(methyl methacrylate) (PMMA)/multiwall carbon nanotube (MWCNT) nanocomposites by co-rotating twin screw extruder at 533 K. Thermal analysis results indicate that the miscibility of PC and PMMA is enhanced by MWCNTs. Bead necklace-like morphology of PMMA-rich phase is observed in PC/PMMA/MWCNT nanocomposites with increasing PMMA weight fraction due to the bead necklace-like morphology. The tensile strength of PC/PMMA (75/25)/MWCNT (1 wt.%) nanocomposite is 3% higher than those of PC/PMMA (75/25) alloy. Suppression of die swell by MWCNT filler is observed in the melt flow of PC/PMMA/MWCNT nanocomposites during extrusion.

• 대한기계학회논문집A
• /
• 제27권11호
• /
• pp.1873-1880
• /
• 2003

The sliding wear characteristics of the crane sheave were investigated using a pin on disk rig tester. The experiment was conducted using a high carbon steel wire that was upper material, also carbon steel castings that was disk material. There are various operating conditions in this work. At the room temperature, we carried out the wear test under a grease lubrication and dry condition. The results of wear test showed that an annealed-casted have lower, also the wear curves are linearly increased with increasing of sliding distance. For the specific wear rate of annealed-casted, the wear resistance was increased with decreasing diameter of wire. The wear of a wire and a disk have a different mechanism, the one is the abrasive wear due to fatigue wear under lubrication, another is the adhesion wear under dry condition.

• Carbon letters
• /
• 제11권4호
• /
• pp.298-303
• /
• 2010

A method of functionalization of multi-walled carbon nanotube (MWNT) at room temperature using dry ozone gas is described. The resulting MWNT were characterized by Fourier transform infrared, x-ray photoelectron spectroscopy, and scanning electron microscopy. Combined to these analyses and solubility in liquids, it could be concluded that the dry ozone gas exposure introduces polar functional groups such as carboxylic groups to MWNT similar to acidic modification of MWNT. Particularly, the stable dispersion of MWNT in water after ozone treatment above a critical level could be obtained, implying potential bio-application. The hydrophilic functional groups on the MWNT introduced by ozone oxidation were helpful in improving the interaction with functional groups in PA6 such as $-NH_2$ and -CONH- resulting in improved mechanical properties.

• Bulletin of the Korean Chemical Society
• /
• 제34권11호
• /
• pp.3261-3264
• /
• 2013

Carbon nanocomposites composed of carbon nanostructures and metal nanoparticles have become one of useful materials for various applications. Here we present the preparation and antibacterial activity of CNT-Ag and GO-Ag nanocomposites. Their physical properties were characterized by TEM, XPS, and Raman measurements, revealing that size-similar and quasi-spherical Ag nanoparticles were anchored to the surface of the CNT and GO. The antibacterial activities of CNT-Ag and GO-Ag were investigated using the growth curve method and minimal inhibitory concentrations against Gram-negative and Gram-positive bacteria. The antibacterial activities of the carbon nanocomposites were slightly different against Gram-positive and Gram-negative bacteria. The proposed mechanism was discussed.

• 한국환경과학회지
• /
• 제11권4호
• /
• pp.333-338
• /
• 2002

In this work, the characterization of adsorption of Cu, Zn and Cd on granular activated carbon in water has been studied. The factors that affect adsorption in boundary between activated carbon and wastewater are concentration, temperature, contact time, pH and so on. As the result of this study, the maximum adsorption amount of Cu occurred near pH 7, while that of Zn and Cd was near pH 9.6 and 10, respectively. As contact time and temperature are transformed, such factors as optimum contact time and temperature are taken into consideration in an adsorptive process of heavy metal because an adsorption and a reducing process occur. In isotherm of Freundlich, 1/n values of Cu, Cd capacity were between 0.16 and 0.5.