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용탕단조법에 의하여 제조한 $SiC_p$/Al 복합재료의 2차 성형공정이 기계적 성질에 미치는 영향
서영호,강충길,Seo, Y.H,Kang, C.G 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.11
A metal matrix composites(MMCs) for A16061 reinforced with silicon carbide particles is fabricated by melt-stirring method. The primary products of MMCs billets are prepared by volume fractions 5 vol% to 20 vol% and particle size $13\mu m$ to $22\mu m$.This paper will be made to examine the microstructure and mechanical properties of fabricated $SiC_p$/Al 6061 composite by melt-stirring and squeeze casting method. The MMC billets is extruded at $500^{\circ}C$ under the constant extrusion velocity $V_e$=2mm/min using curved shape die. Extrusion force, particle rearrangement, micro structure and mechanical properties of extruded composites will be investigated. The mechanical properties of primary billets manufactured by melt-stirring and squeeze casting method will be compared with extrusion specimen. The effect of volume fraction and size of the reinforcements will be studied. The increase in uniformity of particle dispersion is the major reason for an improvement in reliability due to hot extrusion with optimal shape die. Experimental Young's modulus and 0.2% offset yield strength for the extruded MMCs will be compared with theretical values calculated by the Eshelby method. A method will be proposed for the prediction of Young's modulus and yield strength in $SiC_p$ reinforced MMCs.
금형 표면코팅이 소재 마찰계수와 드로잉 성형성에 미치는 영향
서영호(Y. H. Seo) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.10
There are various problems such as shape accuracy, weariness and deflection of the tool, and galling in sheet metal forming process depending on utilization of high strength steel. A heat treatment is carried out on the surface of forming tool in order to solve the mentioned problems. It has been demonstrated that the surface coating is effective in reducing wear. However, the fact that the surface properties may affect the characteristics of drawing formability cannot be overlooked. In this research an effect of surface coating, e.g., non-coating, TD (Thermo-Reactive Deposition and diffusion), PVD (Physical Vapor Deposition)_CrN, PVD_TiN, PVD_TiAlN, and PVD_TiCN, on characteristics of friction and drawing formability is considered.
Neural Network 모델을 이용한 가변성형 공정에서의 탄성회복 보정
서영호(Y. H. Seo),송우진(W. J. Song),구태완(T. W. Ku),강범수(B. S. Kang),김정(J. Kim) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
The objective of this study is to compensate the elastic recovery in the flexible forming process using the Neural Network model. The target shape was limited to two-dimensional shape having only one curvature radius in the longitudinal-direction. In order to predict the shape error the neural network model was established based on the finite element (FE) simulations. A series of simulations were conducted considering input variables such as the elastic pad thickness, the thickness of plate, and the objective curvature radius. Then, at sampling points in the longitudinal-direction, the shape errors between formed and objective shapes could be calculated from the FE simulations as an output variable. To obtain the correct objective shape the die shape was adjusted using the neural network model. Finally the experimental result shows that the formed shape was almost agreed with the objective shape.
서영호(Y.H.Seo),조행묵(H.M.Cho),김현정(H.J.Kim),이창식(C.S.Lee) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_1
In order to decrease fuel comsumption rate and emissions, lean burn engine which has equipped swirl control valve, is investigated experimentally on the test bench. Single cylinder engine was used to test the combustion and emission preformance with 4 kinds of swirl valve. Decrease in the carbon manoxide, hydrocarbon and specific fuel consumption was shown at the lean condition, which means that a good choice of swirl valve on the given intake port geometry can be used to increase the combustion efficiency.