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특정두께를 갖는 이방성복합재 구조의 전자파 응답특성 연구
정헌달,김덕주,이윤상 한국군사과학기술학회 1998 한국군사과학기술학회지 Vol.1 No.1
A user friendly computer code(EMCOMST; Electro-Magnetic response for COMposite STructures) was developed which provides with computations of the response characteristics such as reflectance and transmittance to the incident wave angles, frequencies, composite thicknesses, ply orientations, and types of backplate as the linearly polarized transverse electro-magnetic wave is emitted to the advanced composite structures. In this investigation were reviewed the electromagnetic characteristics of the continuous orthotropic fiber-reinforced organic matrix composites with or without ferrite fillers, which are actively applied to low-weight and high-strength aircraft structures. Also were calculated the response of the three layered compound structures which have appropriately stacked above-mentioned materials as transmitting layer, absorbing layer, reflection layer, respectively under the specific thickness constraints for mechanical strength design requirements. For the composite structures presented in this study, minimum reflectance value less than -5㏈ can be obtained in the frequency range of 4 to 12 ㎓. In addition, analysis of structures attached isotropic radar absorbing materials(RAM) is facilitated by putting the material properties in the material input card entries adequately.
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연구논문초록(’81-’90) : SO2 가스에 의한 철 - 규소합금의 고온황화부식에 미치는 탄소의 영향
강성군,정헌달 한국부식학회 1991 Corrosion Science and Technology Vol.20 No.1
The high temperature sulfidation of reaction Fe-5wt% Si alloys containing 0.5, 0.7, 1.0, 1.7 wt% C was investigated in 1 atm So₂ gas pressure at temperature ranging from 650℃ to 800℃. The sulfidation rate of she alloys was determined by thermogravimetric analysis. The structure and the composition of the reaction products were identified by the aid of SEM, EDS, AES analysis and X-ray diffraction technique. The scales formed on the alloy surface consisted of two types of layers : the outer layers (FeO, Fe₃O₄,Fe₂O₃) and the inner layers (FeS, SiO₂). The overall reaction process obeyed a parabolic rate law over the temperature range 650-800℃, in which the reaction rate increased with increasing in the temperature. The activation energies for the sulfidation reaction of Fe-5Si, Fe-5Si-1.7C and Fe-5Si-1.7C were 41.2, 59.3, 96.6 KJ/mol, respectively. The addition of carbon in the Fe-Si alloy retarded the sulfidation reaction by forming the dense outer oxide layer and the thick inner SiO₂ layer. However, the influence of the carbon on the sulfidation retewas not remarkable above 800℃
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SO2 가스에 의한 철 - 규소합금의 고온황화부식에 미치는 탄소의 영향
강성군,정헌달 한국부식학회 1989 Corrosion Science and Technology Vol.18 No.1
The high temperature sulfidation reaction of Fe-Swt% Si alloys containing 0.5, 0.7, 1.0, 1.7wt% C was investigated in 1 atm SO₂ gas pressure at temperature ranging from 650℃ to 800℃. The sulfidation rate of the alloys was determined by thermogravimetric analysis. The structure and the composition of the reaction products were identified by the aid of SEM, EDS, AES analysis and X-ray diffraction technique. The scales formed on the alloy surface consisted of two types of layers: the outer Layers (FeO, Fe₃O₄, Fe₂O₃) and the inner layers (FeS, SiO₂). The overall reaction process obeyed a parabolic rate law over the temperature range 650-800℃, in which the reaction rate increased with increasing in the temperature. The activation energies for the sulfidation reaction of Fe-5Si, Fe-5Si-0.7C and Fe-5Si-1.7C were 41.2, 59.3, 96.6 KJ/mol, respectively. The addition of carbon in the Fe-Si alloy retarded the sulfidation reaction by forming the dense outer oxide layer and the thick inner SiO₂ layer. However, the influence of the carbon on the sulfidation rate was not remarkable above 800℃.
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