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공은영,이영석,이경민,최예지 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Fluorinated carbon nanotube(CNT) and graphene nanoplatelet(GNP) were used as reinforcements to improve the mechanical properties of epoxy composite. The effect of fluorination on the surface of CNT and GNP was investigated by x-ray photoelectron spectroscopy(XPS). Thermal stabilities and mechanical properties were analyzed by TGA and tensile and impact strength test. CNT/GNP reinforced epoxy composite exhibited higher strength than CNT reinforced. This result was due to the size effect as the two reinforcements had different aspect ratio. The tensile and impact strength of the composites, which were reinforced with surface fluorinated CNT and GNP, were increased approximately 101 % and 69 % compared to those of neat epoxy. Also, thermal stability of the composites was improved 130 % than that of neat epoxy. These results are due to the synergy effect composed with size effect of reinforcements according to the different aspect ratio and improvement of dispersion in epoxy resin.
공은영,김도영,이경민,이영석 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
To improve electromagnetic interference shielding effectiveness (EMI-SE) of carbon nano fibers (CNF), CNF was deposited with nickel by electroless plating method. Plating time was given as a variable. The samples were named Raw, N1, N3, N5, N7. The surfaces of nickel plated carbon nano fibers were characterized by using ultra-high resolution scanning electron microscope (UHR-SEM). Also the thermal properties were analyzed by thermogravimetry (TGA), the electric properties were tested by sheet resistance analyzer and EMI shielding analyzer. As the result, nickel plated CNF has more high EMI-SE than the Raw-CNF. It is attributed to the Ni plating time and plating morphology. The electromagnetic shielding effectiveness (EMI-SE) of the carbon nano fibers enhanced with increased Ni plating time. But the N5 has high EMI-SE than the N7. Therefore, the uniformity of plating morphology on the surface has more effect on EMI shielding efficiency than the amount of nickel plating.
이강근,공은영 한국지질과학협의회 2002 Geosciences Journal Vol.6 No.3
A model of groundwater flow and contaminanttransport is proposed that incorporates changes in hydraulicparameters due to biomass growth. The model simulates the cou-pled transport phenomena of biodegradable organic contaminantssuch as hydrocarbon compounds, dissolved oxygen, and biomass.The model starts with flow simulation to compute the velocityfield, which is used to simulate solute transport by the method ofcharacteristics and the finite difference method. The reactionequation incorporating biodegradation kinetics is solved to com-pute the biomass increase. The increased biomass is transformedto biofilm thickness, which reduces the porosity and permeability.The porosity and permeability are updated at each time step of thecomputation. Numerical simulations show that the transport sim-ulations, if the reduction of hydraulic parameters is ignored, arelikely to overestimate the extent of contaminant plume and under-estimate the peak concentration of the plume.
최예지,이경민,공은영,이영석 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Carbon black(CB) is functionalized via direct fluorination according to different partial pressure of fluorine and CB/epoxy composites are prepared. The surface properties and dispersion of untreated and fluorinated CB are investigated by X-ray photoelectron spectroscopy (XPS) and UV-spectroscopy, respectively. Then, physical properties of CB/epoxy are conducted via tensile, impact test and thermal creep behavior. As the results, the tensile strength of fluorinated CB/epoxy composites were improved by maximum 33% increase than that of untreated CB/epoxy composites. Also, the thermal creep behavior of fluorinated CB/epoxy composite is remarkably enhanced. These results are attributed to improvement of dispersion of CB and adhesion of it with epoxy resin, which result from developed functional groups containing fluorine by direct fluorination of CB.
Improved mechanical properties of long carbon fiber/epoxy composite by fluorination
김경훈,김지욱,공은영,송은지,이영석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Recently, the use of carbon fiber reinforced plastics (CFRP) has been rapidly increasing around the world. There are many used and abandoned CFRP or left remnant carbon fiber in the manufacturing process, however, they have to be recycled for environment. In this study, the long carbon fiber (LCF; 1 cm) surface is modified by fluori-nation and it is used as a reinforcement of epoxy composite to enhance mechanical properties. The surface chemical compositions, mechanical properties and fracture surface morphologies are evaluated. Tensile strength and modulus of the fluorinated LCF/epoxy composites enhanced up to about 21% and 5% compared to that of pristine LCF/epoxy composites, respectively.
VOCs gas adsorption properties of CuO-introduced activated carbon fibers by electroless plating
김민지,김지욱,공은영,김경훈,최석순,이영석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
The volatile organic compounds (VOCs) is a major environmental problem as the major greenhouse gas. In this study, CuO doped activated carbon fibers (ACFs) were prepared using electroless plating method to improve the adsorption property of VOCs. The crystalline phase of CuO-introduced ACFs was determined using X-ray diffraction (XRD, Empyrean), and specific surface area was assessed by N2 adsorption at 77K. The VOCs adsorption experiment was carried out using gas chromatography (GC), and benzene and toluene gas were used as the VOCs gas, under the 100 ppm gas concentration, gas flow rate of 300 cc/min and 0.01 g adsorbent. As a result, in case of toluene gas adsorption, the breakthrough time was increased up to 2 h, while benzene was increased 14 h. These results can be used that removal technique of carcinogenic materials such as toluene and benzene.
Improved thermal property of modified expanded graphite/epoxy composites
최예지,한정인,김지욱,공은영,이영석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
To improve thermal property of epoxy composites, expanded graphite (EG)/epoxy composites were prepared, in which the EG was modified by different oxyfluorination conditions. The surface-chemical property of oxyfluorinated EG was investigated by X-ray photoelectron spectroscopy (XPS). The fracture surfaces and thermal property of these composites were measured by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) according to the conditions of oxyfluorination. The oxyfluorinated EG/epoxy composites showed ~27% enhancement of thermal stability as compared to neat epoxy. Especially, OF55-EG/epoxy composite appeared the highest thermal stability. These results were indicated that interfacial interaction between EG and epoxy resin was improved by oxyfluorination due to the functional groups including oxygen and fluorine which increase the polarity on the surface of EG. Therefore, oxyfluorination improved the thermal property of EG/epoxy composites.
Electrochemical properties of TiO<sub>2</sub>/ACF composites for supercapacitor
강다희,최예지,한정인,공은영,이영석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
In this study, TiO<sub>2</sub>/activated carbon fibers (ACF) composites are prepared without heat-treatment as supercapacitor electrode materials. ACF are treated with different concentration of titanium isopropoxide solutions. These treated ACFs are calcinated by ultrasound energy at room temperature. The morphology and crystallinity of prepared samples are estimated by scanning electron microscope (SEM) and x-ray diffraction (XRD), respectively. The electrochemical properties of TiO<sub>2</sub>/ACF com-posites based electrodes are estimated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the TiO<sub>2</sub>/ACF composite electrode led to 95% improvement in the specific capacitance as compared to pristine ACF electrode. These results are attributed that TiO<sub>2</sub> doped on ACF surface enhances the wettability of electrode and increases ion-transport rate within ACF pores.