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Tool Design and Experimental Verification for Multi- Stage Cold Forging Process of the Outer Race
Ku, Tae-Wan,Kang, Beom-Soo 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.9
The outer race of constant velocity joints with six inner ball grooves has conventionally been produced using a multi-stage warm forging process, which consists of 9 operations such as billet cutting, forward extrusion, upsetting, backward extrusions, necking, ironing, sizing, and machining. In this study, a multi-stage cold forging process derived from process assessment to replace the traditional warm forging is presented. Detaily, both backward extrusions of the conventional one are redesigned as one operation, and the necking, ironing and sizing are combined into a single necking-ironing-sizing process, thus the proposed cold forging consists of 6 operations. To solve the tool interference in the combined necking-ironing-sizing process, and to facilitate extraction of the forged workpiece from the die cavity, a solid groove punch for shaping the inner ball grooves is redesigned with six-segmentalized grooving knives. Numerical simulation of each sequence is performed to ensure the appropriateness of the suggested process, and the structural integrity is also evaluated. Experimental investigations are carried out using SCr420H billet material. It is shown that this multi-stage cold forging process could be applied to the mass production of the outer race, with the dimensional variation of under 2.0% between the required and the forged geometries.
Ku, Tae Wan,Ryu, Ho Yeun,Lee, June Key,Kang, Beom Soo Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.340-341 No.1
<P>The main goal of this study was to develop the technique of process design and manufacturing for a rectangular deep drawn cup with very narrow width by using finite element analysis scheme and a series of experiments. The manufacturing process of this rectangular cup required several intermediate steps to generate the final shape. The multi-stage deep drawing process was applied to finite element analysis, and a continuous progressive press was employed in a series of experiments. Final specifications of the rectangular deep drawn cup were length of 33.70mm, height of 48.30mm and width of 3.46mm, respectively. In this study, finite element analysis for this drawing process was carried out from the first to the seventh stage, and a series of practical experiment was performed. These simulated results of the rectangular cup were compared with the prototypes of the experiments in view of the deformed shape in each mid-part. The results of finite element analysis showed good agreement with those from the experiments.</P>
성인형 호흡장애 증후군 ( ARDS ) 환자에서 혈중 모체 ( Complement ) 의 변화
김완동(Wan Dong Kim),김영선(Young Sun Kim),조성우(Sung Woo Cho),권순구(Sun Ku Kwon),정연태(Yun Tae Jung),김용훈(Yong Hun Kim),박춘식(Choon Sik Park) 대한내과학회 1989 대한내과학회지 Vol.37 No.3
N/A We previously reported that patients with ARDS had some serum factors which enhance neutrophil functions in terms of adherence and oxygen radical formation partly through complement activation, In this study, we measured complement C3, C4, C3a and C5a in the serum of patients with ARDS to search for the relation between the change of complement concentration and clinical sequence and the pathogenesis of ARDS. The results were as follows: 1) Although the concentration of C3 was lower in ARDS compared to normal controls, no difference was found between the two groups in the case of C4, 2) The concentrations of C3 and C5a were increased in the ARDS group. 3) The concentrations of C3a and C5a were increased in the ARDS group. In conclusion, in the serum of patients with ARDS, activated fragments of complement were found and the complement may be activated through an alternative pathway.
Relation between Disease Incidence of Bacterial Grain Rot of Rice and Weather Conditions
Noh,Tae-Hwan,Kim,Hyung-Moo,Song,Wan-Yeob,Lee,Du-ku,Kang,Mi-Hyung,Shim,Hyeong-Kwon 한국자원식물학회 2004 Plant Resources Vol.7 No.1
Bacterial grain rot of rice caused by Burkholderia glumae was examined between weather condition and disease incidence. From 1998 to 2000, average disease incidence was 3.0 % without difference in survey regions. However, it was related closely to amount of rainfall that disease incidence higher in 1998 and 2000 to 3.0 % and 3.6 % respectively than 2.3 in 1999 relatively small volum of rainfall season.
Surface Imaging of Barley Aleurone Cell by Atomic Force Microscopy
Kim, Tae-Wan,Huh, Kwang-Woon,Kim, Seung-Hwan,Ku, Hyun-Hwoi,Lee, Byung-Moo,Kim, Jae-Yoon,Seo, Yong-Won The Korean Society of Crop Science 2004 Korean journal of crop science Vol.49 No.1
To observe and analysis ultra-microscopically barley aleurone cell surface, atomic force microscope (AFM) was used. Seed coat of early maturing germplasm, eam9, was dehulled and scanned by non-contact mode. We have obtained the high resolution topographic 3-dimensional image of barley aleurone layer with high resolution. These images showed the membrane proteins in barley aleurone cell. One channel protein and numerous peripheral or integral proteins were detected in a area of 100 $\mu\textrm{m}^2$. Furthermore, we found that their widths were ranged from 50 to 750nm and lengths from 0 to 66 $\mu\textrm{m}$. The thickness of aleurone layer was measured by scanning electron microscope. The thickness at early developmental stage was about 16 and then the aleurone cell enlarged upto 57 $\mu\textrm{m}$${\mu}{\textrm}{m}$ at least until 42 days after anthesis. In this study, we firstly reported on the ultrastructural AFM analysis of living aleurone cell as a biological specimen. It was clearly suggested that AFM will become an powerful tool for probing both the structural properties of biological samples.