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박상우(Sang Woo Park),오개희(Kae Hee Oh),강면규(Myeon Gyu Kang) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.10
철도차량의 경량화를 위해서 오늘날 알루미늄 압출재의 사용이 증가하고 있는 추세이며, 이를 통한 차체 제작이 일반화 되고 있다. 경량화에 대한 요구는 더욱더 가속화되고 있으며, 특히 자기부상열차의 경우 환경규제 및 에너지 효율성 증대의 측면에서 경량화가 더욱 절실히 요구되고 있다. 그러나, 알루미늄 압출의 특성상 폭 대비 두께에 대한 제약이 따르므로 추가 경량화를 위해서는 알루미늄 압출재의 구조적인 연구가 필요하다. 따라서, 본 연구에서는 중공형 알루미늄 압출재의 내부 Rib 형상에 따른 굽힘 특성을 비교함으로써 알루미늄 압출재의 경량화를 이루고자 하였다.
조영근(Young-June Jo),이상곤(Sang-Kon Lee),김병민(Byung-Min Kim),오개희(Kae Hee Oh),박상우(Sang-Woo Park) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.4
The effectiveness of vehicle parts made through extrusion is in the limelight because of the advantages of high strength stiffness materials can be produced and the number of processes can be drastically reduced. Therefore, the parts should have sufficient stiffness and be lightweight enough to improve fuel efficiency. However, the application of extruded aluminum requires pre-bending technologies that can manufacture the complex designs profiles demanded by vehicle parts. The aim of this research is that the development of the variable curvature extrusion technology that can produce a variety of curvature. In order to produce a variable curvature, the guide transfer speed and transfer time should be controlled properly. The guide transfer speed and transfer time were examined by the theoretical analysis. A model was developed to simulate the deformation behaviors of extrusion and bending process from the symmetric bumper with range of radii from 1863mm to 2163mm. The theoretical analysis and FE analysis were verified through experimental method.
우수한 기계적 특성과 형상치수 확보를 위한 정밀 압출기술개발
이현철(Lee Hyun-Cheol),이광식(Lee Kwang-Sik),오개희(Oh Kae-Hee),박상우(Park Sang-woo) 한국철도학회 2009 한국철도학회 세미나자료 Vol.2009 No.5
Most advanced countries are researching to apply light weight materials for rolling stock because weight reduction for railway body derives cost-saving, energy-saving, and high-speed. Likewise, current Korea rolling stock field makes arduous efforts of weight-reduction, miniaturization, and high-efficiency to achieve a high-speed railway. Aluminum becomes suitable material for these projects because it is much lighter than steel or stainless. Manufacturing the railway car body by using the Aluminum is increasing because Aluminum is not bringing the corrosion by unique oxidation-passivate. Aluminum extrusion profile for railway body requires a high mechanical property, awn-ate shape dimension, and stable quality because the railway body is composed with many different kinds of extruded profiles. Therefore, it is necessary to research about Aluminum precision-extrusion technology to maintain exit temperature and die load. The goal of this project is applying the Aluminum extrusion profile to next-generation railway car body by developing the Aluminum extrusion profile according to precision-extrusion technology which may maintain isothermal exit temperature.
알루미늄 열간 압출공정의 3차원 유한요소 해석 및 금형설계
조영준(Young June Joe),이상곤(Sang Kon Lee),김병민(Byung Min Kim),오개희(Kae Hee Oh),박상우(Sang Woo Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The growing demand for more fuel-efficient vehicles to reduce energy consumption and air pollution is a challenge for the automotive industry. The characteristic properties of aluminum, high strength stiffness to weight ratio, good formability, good corrosion resistence, and recycling potential make it the ideal candidate to replace heavier materials in the car to respond to the weight reduction demand within the automotive industry. In this paper, FE simulation was carried out to design an appropriate extrusion die for the automobile control arm. Based on the FE simulation result. A new die design has been proposed for uniform material flow in the cross section of extruded product. And then the welding pressure, extrusion load, and the tendency of mandrel deflection were estimated to verify high quality. In the extrusion experiment, it was possible to produce sound product without defects.
곡률압출공정을 이용한 알루미늄 Bumper Back Beam 개발
이상곤(Sang-Kon Lee),조영준(Young-June Jo),김병민(Byung-Min Kim),박상우(Sang-Woo Park),오개희(Kae-Hee Oh) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.5
Curvature extrusion process has several advantages in comparison to the conventional extrusion and bending process. In the curvature extrusion, the extruded part is directly bent during extrusion. Therefore, it does not need additional bending process after extrusion. In the curvature extrusion process, it is possible to produce curved extruded products that have a constant or various curvatures. It is essential that we predict the curvatures of the extruded product to meet the required curvatures. This paper proposed a theoretical model that can predict the curvature of extruded product produced by the curvature extrusion process. Using the proposed model the movement of guide tool that causes the bending of extruded product was controlled to produce the required curved automotive Al bumper back beam. The effectiveness of the proposed prediction model and the movement of guide tool were verified by the FE analysis and curved extrusion experiment.
ECAP 강가공에 의한 0.15%C 강의 결정립 미세화
김우진,신동혁,주웅용,오개희,이상우 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.9
Experiments were conducted on 0.15%C steel with an initial grain size of ∼40 ㎛ for obtaining an ultra-fine grain structure and enhanced tensile properties. ECA pressing was successfully conducted at 200℃ by designing the channel angle and the arc of curvature at the outer point of intersection of two channels properly. The Vickers hardness increased significantly by a factor of 1.6 even with a single pass. Subsequently, the hardness increased slightly after second pass. The microstructure was refined after a single pass and consisted of parallel bands of elongated subgrains. These subgrains were developed to fine grains by repeating the pass. At least for 0.15%C steel, it was possible to achieve equiaxed fine grains of ∼0.5 ㎛ by applying 2 passes such that the sample was rotated by 180℃ in the second pass.