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정동원,황재신 濟州大學校 海洋硏究所 2003 해양과환경연구소 연구논문집 Vol.27 No.-
In the present work a finite element formulation using dynamic explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. Did correction of deformities public decision simulation to esteemed daughter benevolent person who influence in transformation that Binder Wlap has being formed using dynamic extensive method. In this work. brief descriptions of the formulation and the factor study are presented. Further. the simulated results for the total auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.
정동원 고려대학교 의과대학 1988 고려대 의대 잡지 Vol.25 No.1
The purpose of this study is to compare bone scintigraphy with histological findings of avascular necrosis of femoral head in the steroid-treated rabbits. Of thirty-five rabbits, thirty rabbits were administrated a weekly dosage of five milligrams of methylprednisolone for ten weeks and five of them were employed as control. Serial scintigraphy of the femoral head with 99m technetium-methylene diphosphonate (99mTc-MDP) was taken weekly from two weeks to ten weeks after administration of methylprednisolone and this was studied comparatively with corresponding histological findings. The results obtained are as follows: 1. In the experimental group, the mean uptake ratio of the femoral head to greater trochanter with 99mTc-MDP was 1.57± 0.03 at two weeks, and slightly decreased to 1.20±0.03 at four weeks, decreased remarkably to 0.76±0.04 at five weeks, 0.77±0.01 at six weeks, 0.71±0.02 at eight weeks, and 0.75±0.03 at ten weeks. 2. The histological findings revealed that fatty hyperplasia, vascular hemorrhage and congestion in the subchondral bone and metaphysis of femoral head at five to ten weeks, and the early findings of avasuclar necrosis at eight to ten weeks were observed. The above experiment suggests that decreased uptake of the 99mTc-MDP in the femoral head treated with methylprednisolone in the early stage indicates fatty hyperplasia and intramedullary hemorrhage with damage of vascular wall in bone marrow, and those induce avascular necrosis in the late stage.
정동원 濟州大學校工科大學産業技術硏究所 1999 尖端技術硏究所論文集 Vol.10 No.1
In this study, the forming behavior of Tailor Welded Blanks is analyzed by using the explicit finite element code PAM-STAMP and LS-DYNA3D. The dynamic explicit finite element method is applied effectively to analyze total auto-body panel stamping processes, which include the forming stage, the trimming stage and the springback stage consecutively. The formability and the weld line movement in stamping with Tailor Welded Blanks were investigated through cylindrical cup and QTR-OTR-FRT. Tailor Welded Blanks are defined as two or more separate pieces of sheet material having the same or dissimilar thickness and/or physical properties, joined together before forming. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.
반구형 딥-드로잉 공정에서 동적 외연적 해석방법에 관한 연구
정동원,황재신 제주대학교 공과대학 첨단기술연구소 2003 尖端技術硏究所論文集 Vol.14 No.2
In the present work a finite element formulation using dynamic explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. Analyzed auto-panel stamping process correction of forming using common use software called Dynaform using dynamic extensive method. The developed algorithm is also capable of calculating the diagram black shapes as the initial state of binder wrap condition for large scale parts such as a fender or a rear quarter part. Further, the simulated results for the total auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction. weight saving, and improvement of strength.
동적-외연적 유한요소법을 이용한 Hydro-forming 공정에 관한 연구
정동원,황재신 제주대학교 공과대학 첨단기술연구소 2004 尖端技術硏究所論文集 Vol.15 No.1
In the present work, a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of Hydro-forming processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Hydro-forming process for auto-body panel forming has been analyzed by using dynamic-explicit finite element method. Further, the simulated results for the Hydro-forming processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.
정동원,안현길 제주대학교 공과대학 첨단기술연구소 2005 尖端技術硏究所論文集 Vol.16 No.2
A method is described for mapping a three-dimensional computer modelled surface into the two-dimensional plane. The technique is referred to as geometric modelling and provides in the computer a transformation between the flat sheet and the final surface. The initial blank shape represents an approximate development of the final formed three dimensional surface. It was used the initial constant area mapping hypothesis in this paper. This technique is intended to be developed as the basis of an interactive computer design capable of dealing with typical stamping process, including deep parts and complex shapes.
정적 외연적 유한요소법을 이용한 비드 펀치 행정거리가 드로우비드 공정에 미치는 영향에 관한 연구
정동원 濟州大學校 基礎科學硏究所 2003 基礎科學硏究 Vol.16 No.1
The bead is used to provide properly restraining force in the sheet metal forming process. This bead process includes bending and geometrical non-linearity, and affects the state of binderwrap. Therefore, the analysis of bead process is very important to obtain the desired formability. In this paper, the research about the influence of the punch stroke of bead on the draw-bead process was conducted. Results from the analysis will give useful information to the effective tool design of blank forming process. To analyze the bead process, an elasto-plastic finite element formulation is constructed from the equilibrium equation and the considered boundary conditions involved a proper contact condition. The static-explicit finite element method as a numerical method for the analysis was applied to the analysis program code. It was found that this method could solve too much computation time and convergence problem owing to high non-linearity of bead forming process.
One-Step 이론을 이용한 Roof 판넬 해석에 관한 1차 연구
정동원,안현길 濟州大學校 海洋硏究所 2004 해양과환경연구소 연구논문집 Vol.28 No.1
The static implicit finite element method and the dynamic explicit finite element method are applied effectively to analyze total auto-body panel stamping processes, which include the forming stage. Analyzed complicated and abnormal Large size auto-body panel using common use program called AutoForm. Analysis results examining possibility and validity of the formulation and the factor study are presented. Further, the simulated results for the total auto-body panel stamping Processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction. weight saving, and improvement of strength.