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문바울(Pa Ul Mun),오중석(Joungseok Oh),박정후(Junghu Park),강동명(Dongmyeong Kang) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
The energy crisis have faced and the environmental problems have recently raised. In this situation, the interest in light-weight frame for small & medium sized bus. this work is to develop a composite frame which will be applicable to relatively small & medium sized bus. For this frame a high efficiency and light-weight frame was designed with the proposing structural design procedure and a light composite structure frame. In the structural analysis including load case study, stress, deformation and buckling anlysis wer performed using the Finite Element Method. In its manufacturing, ther was utilized the wet lay-up and the result compared with structural experiments and structural anlysis.
Numerical analysis of the subsonic flow around a three-dimensional cavity
최홍일,Pa-ul Mun,김재수 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.6
Flight vehicles such as wheel wells and bomb bays have many cavities. The flow around a cavity is characterized as an unsteady flow because of the formation and dissipation of vortices brought about by the interaction between the free stream shear layer and the internal flow of the cavity. The resonance phenomena can damage the structures around the cavity and negatively affect the aerodynamic performance and stability of the vehicle. In this study, a numerical analysis was performed for the cavity flows using the unsteady compressible three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equation with Wilcox's turbulence model. The Message Passing Interface (MPI) parallelized code was used for the calculations by PC-cluster. The cavity has aspect ratios (L/D) of 2.5 ~ 7.5 with width ratios (W/D) of 2 ~ 4. The Mach and Reynolds numbers are 0.4 ~ 0.6 and 1.6×106, respectively. The occurrence of oscillation is observed in the "shear layer and transient mode" with a feedback mechanism. Based on the Sound Pressure Level (SPL) analysis of the pressure variation at the cavity trailing edge, the dominant frequencies are analyzed and compared with the results of Rossiter's formula. The dominant frequencies are very similar to the result of Rossiter's formula and other experimental data in the low aspect ratio cavity (L/D = ~ 4.5). In the large aspect ratio cavity, however, there are other low dominant frequencies due to the leading edge shear layer with the dominant frequencies of the feedback mechanism. The characteristics of the acoustic wave propagation are analyzed using the Correlation of Pressure Distribution (CPD).
이민근(Min Geun Lee),정상원(Sang Won Chung),문바울(Pa Ul Mun) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The springback to the metal forming is one of the most important issues. The springback of high strength steel under U-bending has been studied for a material orientation in which U-bending process is presumed to have the highest forming. In the study, the effects of the variable on springback of U-bending depending on intrusion direction, forming speed and blank holding force are investigated. And numerical analyses are performed to predict the amount of springback and to analyze the results. Practical and physical meaning of the results are discussed.