• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.865-870
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• 2012

CFRP of the advanced composite materials as structure materials for vehicles has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness compared with conventional materials. This study is to investigate the energy absorption characteristics and collapse mode of CFRP single and double hat shaped structural member under the axial static collapse test. The CFRP single and double hat shaped structural members stacked at different angles (${\pm}15^{\circ}$, ${\pm}45^{\circ}$, ${\pm}90^{\circ}$, $90^{\circ}/0^{\circ}$ and $0^{\circ}/90^{\circ}$ where the direction on $0^{\circ}$ coincides with the axis of the member). The axial static collapse tests were carried out for each member. Collapse mode and energy absorption characteristics of the each member were analyzed.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.890-895
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• 2002

Effect of the sintering time on the microwave dielectric properties of the layered Functionally Graded Materials(FGMs) of the Mg0.93Ca0.07TiO3(MCT) with (Ca0.3Li0.14Sm0.42)TiO3(CLST) ceramics was investigated. The dielectric constant of layered FGMs specimens showed a nearly constant value and did not change significantly with sintering time. The quality factor, however, was affected by the relative density and thermal stress developed in each dielectric layer. With an increase of the relative density and the decrease of the induced thermal stresses, quality factor of the layered FGMs specimens increased and the quality factor was incluenced sensitively by the change of compressive stress developed in MCT layers which had a lower thermal expansion coefficient than that of CLST. For the layered FGMs specimen sintered at 1300$^{\circ}C$ for 9h, the compressive stress developed in MCT layer showed the maximum value, which, in turn, the quality factor of the specimen was the minimum value.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.83-88
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• 2020

Recently, radiation shielding sheets made of eco-friendly materials have been widely used in medical institutions. The shielding sheet is processed into a solid form by thermoforming by mixing a shielding material with a polymer material. The base is resin-based and has a limit in tensile strength, and for this purpose, fibers such as non-woven fabrics are used on the surface. The shielding sheet process technology has a problem in that the tensile strength rapidly decreases when the content of the shielding material is increased to increase the shielding performance. In order to improve this, this study intends to compare and evaluate the method of laminating and coating the fibers in the sheet process. In comparison of the three types of sheets, there was no difference in shielding performance between the fiber-coated sheet and the compression sheet, but there was a large difference in tensile strength.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.163-166
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• 2009

다중접합 초 고효율 태양전지 제조를 위해 SiC 매트릭스를 이용한 실리콘 양자점 초격자 박막을 제조하고 특성을 분석하였다. $SiC/Si_{1-x}C_x$(x ~ 0.31)로 실리콘 양자점 초격자 박막을 Si과 C target을 이용한 co-sputtering법으로 초격자 박막을 제조하고, $1000^{\circ}C$에서 20분간 열처리를 하였다. high resolution transmission electron microscopy 사진으로 약1~7nm 크기인 양자점 생성과 분포 밀도를 확인할 수 있었으며, grazing incident X-ray diffraction (GIXRD)를 통해서 Si(111)과 $\beta$-SiC(111)이 생성되었음을 알 수 있었다. Auger electron spectroscopy (AES)측정에서 stoichiometric SiC층과 Si-rich SiC층의 Si 원자농도 (56%, 69%)와 C 원자 농도 (44%, 31%)를 알 수 있었으며, Fourier transform infra-red spectroscopy (FTIR)측정에서 SiC 픽의 위치가 767에서 $800cm^{-1}$으로 이동하는 것을 알 수 있었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.19-27
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• 2021

In this study, a high-pressure subsacle thrust chamber was developed to verify the core technology for KSLV-II performance enhancement. The core technologies are the design of an injector for high-pressure combustion, development of a combustion stabilization device using the additive manufacturing technique, and the design and fabrication of mixing head and regeneratively cooled combustion chamber. The core technologies, which have been verified through the development of high-pressure subscale thrust chamber, will be used to develop large engine liquid rocket engine thrust chamber in the future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.464-464
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• 2007

환경오염으로 인한 각종 질병 및 증후군 등의 발생으로 가정용 산업용에서 환경관련 기술들이 다양한 분야로 확대되고 있다. 본 연구에서는 양이온 및 음이온 양쪽이온을 최대한 발생시키며, 오존 발생량은 억제하고 소비전력을 절감하고자 Ag-Pd 전극을 적용한 세라믹스 클러스터를 개발하였다. Ag-Pd 전극과 매칭되는 세라믹스 조성을 개발한 후 적층공정 기술을 이용하여 후막형 클러스터를 제조하였다. 전극 패턴모양, 전극간 방전간격 및 전극 보호층의 두께에 따른 음이온 발생량을 측정하여 최적화를 위한 실험을 진행하였으며, 음이온 발생량 100만개이상, 오존발생량 0.6ppb인 특성을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.124.2-124.2
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• 2015

최근 에너지 효율을 향상시키고 감성과 기능성을 동시에 만족시킬 수 있는 스마트 윈도우 (Smart Window) 기술이 큰 주목을 받고 있다. 신개념의 하이브리드형 열선차단 코팅기술로 고투명, 고단열 등 복합기능을 가지고 있음. 4계절 변화가 뚜렷한 대한민국 실정에 가장 적합하여 건축물의 냉 난방 에너지를 최소화하는데 크게 기여할 것으로 기대된다. 단열필름 제조 방식에는 보급형 필름으로 염료 방식, 금속 방식 등이 있고 고성능 필름에는 나노 세라믹 방식과 스퍼터 방식+세라믹 방식을 융합한 필름(스퍼터 IR 필름)이 있다. 본 연구에서는 DC pulse sputter를 이용하여 고굴절율 물질인 TiO2와 저굴절률 물질인 SiO2를 적층으로 성장시켜 단열 스마트필름을 제작해 보았다. 높은 가시광 투과율과 IR 차페 성능을 확인하였고, 제작한 스마트필름을 또다른 윈도우 기술에 적용하는 연구를 진행하였다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.549-554
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• 2000

In this study, using linear and nonlinear deformation theories and by closed-form analysis and finite difference energy methods, respectively, various buckling load factors are obtained for stiffened laminated composite cylindrical panels with rectangular type longitudinal stiffeners and various longitudinal length to radius ratios, which are made from Carbon/Epoxy USN150 prepreg and are simply-supported on four edges under uniaxial compression, and then for them, buckling behavior design analyses are carried out by the nonlinear search optimizer, ADS

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.54-65
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• 2022

We are developing a compact ignition device that can provide a multi-ignition capability for an upper stage methane engine of a two staged small satellite launch vehicle. Firstly, the multi-ignition device is designed and built as an integral part of an additively manufactured mixing head. Secondly, the ignition device requires no separate high-pressure vessels to store ignition propellants as they are branched out from the main feed lines for the mixing head. We performed experiments at various levels, including igniter autonomous tests, thrust chamber ignition and combustion tests on the new compact ignition device which is integrated in the thrust chamber of one-tonf class liquid oxygen/liquid methane engine, and confirmed stable ignition performance.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.34-39
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• 2008

In this study, CFRP(Carbon Fiber Reinforced Plastics) that has high specific strength and elastic modulus and low thermal strain was used as a material for the lightweight structural member. CFRP is a fiber material as anisotropic material. The anisotropic material is characterized by the change of its mechanical properties according to stacking orientation angle. CFRP orientation angle was oriented in [A/B]s in order to examine the effect of CFRP orientation angle on the characteristics of energy absorption. CFRP is very weak to the impact from the outside. So, when impact is applied to CFRP, its strength is rapidly lowered. The hybrid material was manufactured by combining CFRP to aluminum which is lightweight and widely used for structural members of the automobile. The hybrid member was shaped as a side member that could support the automobile engine and mount and absorb a large amount of impact energy at the front-end in case of automobile collision. The bending test device was manufactured in accordance with ASTM standard, and mounted to UTM for bending test. For comparing bending characteristics of the hybrid member with those of Aluminum and CFRP member, tests were performed for aluminum, CFRP and hybrid member, respectively.