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KBC2005 기준과 개선된 유전자알고리즘(DGA)을 이용한 강구조 골조의 설계
이홍우(Lee, Hongwoo) 서원대학교 미래창조연구원 2009 과학과 문화 Vol.6 No.1
This study uses the modified genetic algorithm, DGA, for designing the steel frame. The DGA method is an improved genetic algorithm with the direction-vector based search technique. Two types of direction vectors are defined without sensitivity analysis. It is demonstrated that DGA is an effective design method by comparing with the simple genetic algorithm. DGA includes two stages. In the first stage, a global search is carried out over the design search space like as a simple genetic algorithm. In the second stage, a local search is executed by the two types of direction vectors. Those direction vectors don’t use the gradient information and they are appropriate to the discrete non-differentiable functions which compose the structural design problem. DGA and the simple GA are applied to the problem of 2-span 3-story steel frame design. The steel frame is designed by ‘Korea Building Code - Structures 2005(chapter 7. Steel Structure Design)’ which is similar to the AISC-LRFD. The frame design results shows that DGA converged rapidly to a reliable solution.
이홍우(Hongwoo Lee),조진래(Jinrae Cho),유완석(Wansuk Yoo) 한국자동차공학회 2004 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Recently, the natural element method (NEM) based on the natural neighbors and the Bubnov-Galerkin approximation is being explored as a possible solution to the common defects of meshfree methods, the enforcement of essential boundary condition and the numerical integration. In which, Laplace interpolation functions defined using the Voronoi diagram and the Delaunay triangulation are used for both trial and test basis functions. And, the numerical integration is carried out with the help of the background cell. This paper intends to explore the application of NEM to the 2-D static tire contact problem characterized by the large and almost incompressible deformation.
강연식(Yeonsik Kang),이홍우(Hongwoo Lee),김재현(Jaehyun Kim),정경환(Kyunghwan Chung),이현영(Hyunyoung Lee),남재복(Jaebok Nam) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
POSCO developed a new body concept for electric vehicle (PBC-EV, POSCO Body Concept ? Electric Vehicle) with the aim to identify requirements of new steel grades for electric vehicle and to provide cost efficient steel solutions to customer. The objectives are achieved by advanced steel technologies and engineering design optimization with the best attributes of steel ? its design flexibility, strength, formability and low manufacturing cost. PBC-EV features steel body structure designs that reduce weight to 218kg by 26 percent over a benchmark body of 296kg. The weight reduction has been realized through the use of advanced high strength steel grades by 65% of total body weight. The steel grades include TWIP, 2Gipa grade HPF steels as well as DP, CP and TRIP steels. A number of steel application technologies were also adopted to take the benefit of advanced steels. New forming technologies such as tailored hot press forming and multi-directional roll forming were applied as well as conventional manufacturing methods. Even though there is a cost premium associated with the use of higher grade steels, the consequently achieved weight savings and the optimal use of forming process minimize the overall cost increase of manufacturing and assembly. The total life cycle emission of PBC-EV is reduced by nearly 50 percent comparing to the benchmark internal combustion engine vehicle. These are accomplished while meeting a broad list of global safety requirements such as US FMVSS, IIHS and EuroNCAP. No damage of battery cell in the crash simulations is observed. In the last stage hardware demonstration was done by building BIWs (Body-in-White) excluding opening parts and fenders. It is very important for automakers to avoid unintended consequences by using eco-friendly steel technologies for advanced powertrain vehicle. With this project advanced steel solutions which are not only lighter and safer but greener can be provided to automakers.
타이어의 그루브 폭에 따른 젖은 노면에서의 제동특성 연구
손정삼(Jungsam son),이홍우(Hongwoo Lee),조진래(Jinrae Cho),김기전(Gijeon Kim),우종식(Jongshik Woo) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
When a vehicle is running rapidly on the wet-road, the tire contact force decreases because of the occurrence of thin water film between road and tire. In the severe case, tire may float over the road slide on the road. this phenomenon is called "hydroplaning". Hydroplanning is seriously influenced by road property, internal pressure, the vehicle velocity, the tread pattern, and so on. In this paper, the width of tire-groove among several factors is considered and 3 groove models are applied. The rolling analysis of tire is performed by MSC/Dytran.
복합하중조건에서 AHSS 점용접부의 준정적 파단특성 연구
하지웅(Jiwoong Ha),허훈(Hoon Huh),이홍우(Hongwoo Lee),김교성(Kyo-seong Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This paper is concerned with the failure characteristic and the failure load of spot welds of AHSS under combined axial and shear loading conditions. The testing fixture and the specimen are newly designed to impose the pure-shear load on a spot weld. The testing fixture and the specimen proposed Song and Huh1 are used to impose the combined axial and shear load from 0° to 75° on spot welds. Using those testing fixture and specimens, failure tests of the spot weld of 590TRIP 1.2t, 780DP 1.0t, and 980DP 1.2t are conducted with seven different combined loading conditions. Based on the experimental results, failure loads and failure behaviors of the spot weld are investigated with respect to different loading angles. Failure loads of the spot weld obtained from failure tests are interpolated to construct Song and Huh’s failure model1, which facilitates the failure description of spot welds in the macroscopic finite element analysis of auto-body structure.