• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.72-75
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• 2023

Carbon neutrality has been emerged as important mission for all the manufacturing industry to reduce energy usage and carbon emission equivalent. Korean semiconductor and display manufacturing industries are also in huge interest by minimize the energy usage as well as to find a less global warming product gases in both etch and cleaning. In addition, Korean government is also investing long term research and development plan for the safe environment in various ways. In this paper, we revisit previous research activities on carbon emission equivalent and current research activities performed in semiconductor process diagnosis research center at Myongji University with respect to the reduction of NF3 usage for the PECVD chamber cleaning, and we present the analytical result of the exhaust gas with residual gas analysis in both 6 inches and 12 inches PECVD equipment. The presented result can be a reference study of the development of new substitution gas in near future to compare the cleaning rate of the silicon oxide deposition chamber.

• 한국수소및신에너지학회논문집
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• 제25권6호
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• pp.620-628
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• 2014

Direct Carbon Fuel Cell(DCFC) is one of new power generation that the chemical energy of solid carbon can be converted into electrical energy directly. At the high temperature, the electrochemical reaction of the carbon takes place and the carbon reacts with oxygen to produce carbon dioxide as followed overall reaction ($C+O_2{\rightarrow}CO_2$). However, in case of using the raw coals as a fuel of DCFC, the volatile matter containing carbon, hydrogen, and oxygen produces at operating temperature. In this study, the electrochemical reaction of Adaro coal was compared with Graphite. This work focused on the electrochemical reaction of two kinds of solid carbon by Electrochemical Impedance Spectroscopy(EIS). The EIS results were estimated by equivalent circuit analysis. The constant phase element(CPE) was applied in Randle circuit to explain an electrode and fuel interface. The correlation between the fuel characteristic and electrochemical results was discussed by elements of equivalent circuit of each fuel.

• 한국환경보건학회지
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• 제24권1호
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• pp.32-37
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• 1998

The Carbon Dioxide is the gas, which causes green house effects, unusual changes in the weather, destruction of the life. Almost every nation in the world is trying to search the countermeasure to this poisonous gas. I synthesized $Fe_3O_4$ and NaOH, in order to decompose the Carbon Dioxide. Among the particles synthesizing $Fe_3O_4$, I chose the equivalent ratio 1.00 which can decompose the Carbon Dioxide best, and fixed that equivalent ratio and added the 0.005-3.00 mole percentage of NiCl$_2$ and synthesized $Fe_3O_4$. I studied the decomposition of the Carbon Dioxide and methanized reaction, by measuring its crystal structure, thermochemistrical character and specific surface area. In decomposing the Carbon Dioxide, I used oxygen-deficit Magnetite which I produced by injecting the hydrogen gas into the synthesized sample. I observed the methanization reaction by raising the temperature of sample up to 650$\circ$C and having it reacted with the hydrogen gas. The decomposition of the Carbon Dioxide was added 0.005, 0.03, 0.05 mole percentage of NiCl$_2$ was more effective than pure $Fe_3O_4$. All sample in which the decomposition of the Carbon Dioxide took place produced the methane gas.

• Structural Engineering and Mechanics
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• 제70권6호
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• pp.737-750
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• 2019

This paper investigates the static and dynamic behaviors of imperfect single walled carbon nanotube (SWCNT) modeled as a beam structure by using energy-equivalent model (EEM), for the first time. Based on EEM Young's modulus and Poisson's ratio for zigzag (n, 0), and armchair (n, n) carbon nanotubes (CNTs) are presented as functions of orientation and force constants. Nonlinear Euler-Bernoulli assumptions are proposed considering mid-plane stretching to exhibit a large deformation and a small strain. To simulate the interaction of CNTs with the surrounding elastic medium, nonlinear elastic foundation with cubic nonlinearity and shearing layer are employed. The equation governed the motion of curved CNTs is a nonlinear integropartial-differential equation. It is derived in terms of only the lateral displacement. The nonlinear integro-differential equation that governs the buckling of CNT is numerically solved using the differential integral quadrature method (DIQM) and Newton's method. The linear vibration problem around the static configurations is discretized using DIQM and then is solved as a linear eigenvalue problem. Numerical results are depicted to illustrate the influence of chirality angle and imperfection amplitude on static response, buckling load and dynamic behaviors of armchair and zigzag CNTs. Both, clamped-clamped (C-C) and simply supported (SS-SS) boundary conditions are examined. This model is helpful especially in mechanical design of NEMS manufactured from CNTs.

• Advances in nano research
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• 제7권1호
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• pp.39-49
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• 2019

This paper focuses on two main objectives. The first one is to exploit an energy equivalent model and finite element method to evaluate the equivalent Young's modulus of single walled carbon nanotubes (SWCNTs) at any orientation angle by using tensile test. The calculated Young's modulus is validated with published experimental results. The second target is to exploit the finite element simulation to investigate mechanical buckling and natural frequencies of SWCNTs. Energy equivalent model is presented to describe the atomic bonding interactions and their chemical energy with mechanical structural energies. A Program of Nanotube modeler is used to generate a geometry of SWCNTs structure by defining its chirality angle, overall length of nanotube and bond length between two adjacent nodes. SWCNTs are simulated as a frame like structure; the bonds between each two neighboring atoms are treated as isotropic beam members with a uniform circular cross section. Carbon bonds is simulated as a beam and the atoms as nodes. A finite element model using 3D beam elements is built under the environment of ANSYS MAPDL environment to simulate a tensile test and characterize equivalent Young's modulus of whole CNT structure. Numerical results are presented to show critical buckling loads, axial and transverse natural frequencies of SWCNTs with different orientation angles and lengths. The understanding of mechanical behaviors of CNTs are essential in developing such structures due to their great potential in wide range of engineering applications.

• 대한화학회지
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• 제40권5호
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• pp.308-316
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• 1996

Impedance Spectroscopy를 통하여 조밀한 표면조직을 갖는 glassy carbon과 PVDF 합성흑연의 표면에 대한 전기화학적 거동을 조사하였다. 이들 두 탄소재료는 모두 전압에 대한 높은 Faraday-임피던스의존성이 나타났으며, 이를 평가하기 위한 등가회로는 PVDF 흑연의 경우 lassy carbon의 등가회로에 소수성 결합제에 의한 저항과 축전용량이 추가된 형태로 나타났다. 또한 디들 재료는 표면의 차이로 인한 전기화학적 거동의 차이도 나타났다.

• 한국환경보건학회지
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• 제21권2호
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• pp.68-74
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• 1995

The optimum conditions was synthesized for the formation of Magnetite ($Fe_3O_4$) by air bubbling with the suspensions obtained by mixing Ferrous sulfate ($FeSO_4\cdot 7H_2O$) and Sodium Hydroxide (NaOH) solution in various values equivalent ratio($R=2NaOH/FeSO_4$) were studied. The changes of the structure were measured with XRD, $EM and BET. Equivalent ratio R: 0.65 was synthesized Goethite ($\alpha$-FeOOH), which becomes Maghemite ($\gamma=Fe_2O_3$) by dehydration, reduction and oxidation process. At the equivalent ratio over 1 (R>1), Magnetite ($Fe_3O_4$) was synthesized directly. The oxygen-deficient Magnetite ($Fe_3O_{4-\delta}$), which is obtained by flowing $H_2$ gas(100 ml/min) through the synthesis Magnetite at 350$\circ$C for 4 hr. By using it, was researched the decomposition reaction of $CO_2$. $CO_2$ was decomposed nearly 100% in 45 minutes by the oxygen-deficient Magnetite.

• Advances in nano research
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• 제3권1호
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• pp.29-37
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• 2015

In the current study, the nonlinear vibration properties of an embedded zigzag single-walled carbon nanotube (SWCNT) are investigated. Winkler-type model is used to simulate the interaction of the zigzag SWCNTs with a surrounding elastic medium. The relation between deflection amplitudes and resonant frequencies of the SWCNT is derived through harmonic balance method. The equivalent Young's modulus and shear modulus for zigzag SWCNT are derived using an energy-equivalent model. The amplitude - frequency curves for large-amplitude vibrations are graphically illustrated. The simulation results show that the chirality of zigzag carbon nanolube as well as surrounding elastic medium play more important roles in the nonlinear vibration of the single-walled carbon nanotubes.

• Journal of Welding and Joining
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• 제6권2호
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• pp.40-46
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• 1988

The effect of heat input on the content of residual .delta.-ferrite and the hot cracking susceptibility in the austenitic stainless steel overlaid on the carbon steel was studied in the range of heat input from 7.5 to 15.1 KJ/cm. Present study shows that residual .delta.-ferrite content in the overlay is mainly determined by the dilution of the base metal (carbon steel) which is in turn affected by heat input, i.e. the amount of dilution decreases as heat input increase. Accordingly, higher heat input results in a substantial increase in Cr equivalent but a little increase in Ni equivalent due to the less dilution of carbon from base metal. This fact can explain the result obtained in this study, i, e, the higher content of .delta.-ferrite in the weld deposit made with higher heat input. This in turn causes more resistant overlaying weld metal to hot cracking.

• 항공우주기술
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• 제1권1호
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• pp.153-162
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• 2002

킥모터용 노즐목에 사용되는 공간적으로 보강된 탄소/ 탄소 복합재료의 기계적 물성치를 예측하고, 전체 노즐의 기계적 거동해석을 수행하였다. 이러한 3차원 등가물성치는 노즐의 기계적 거동해석에 필요한 3차원 물성치로 이용된다. 노즐목에 사용되어지는 공간적으로 보강된 복합재료는 그 구조에 따라서 물성치분포가 달라지므로 물성치 예측 프로그램을 개발하였다. 지금 개발되고 있는 킥모터용 노즐은 노즐목의 graphite 또는 공간적으로 보강된 탄소/ 탄소 복합재료, 노즐머리부분과 확장부의 carbon/ phenol, 그리고 확장부 외피의 강철로 구성되어있다. 추력에 가장 큰 영향을 미치는 노즐목의 변형형상은 4-D 탄소/ 탄소 복합 재료가 가장 균일하고, 작은 변형형상을 나타내었다. 이러한 해석 결과에 더하여 4D 탄소/ 탄소 복합재료 노즐목과 그라파이트 노즐목을 가진 모타 시험이 수행되었다.