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A Study on the Backward Extrusion of Internal Spline
YongIl Cho(조용일),JongUng Choi(최종웅),Yuangen Qiu(추연근),Heayong Cho(조해용) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.9
Spline is a machine component using transmits rotating energy with grooves on internal of boss and external periphery of shaft. Internal spline is generally produced by machining process. However, to reduce manufacturing cost and save time, plastic deformation process such as backward extrusion is gradually adapted for spline production. In plastic deformation process, forming load, stress on tools and flow flaws should be taken into account to have sound products. For this purpose, kinematically admissible velocity fields for Upper Bound Method in backward extrusion of internal spline has been suggested, then forming load and relative pressure have been calculated. Internal spline forming experiments have been con-ucted under hydraulic press and the calculated forming load well predicts the load of experiment.
Analysis of SLF Interruption Performance in self-blast Gas Circuit Breaker
Jin-gun Park(박진근),Hee-sup Ahn(안희섭),Jongung Choi(최종웅),Younggeun Kim(김영근),Heayong Cho(조해용) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.9
A self-blast type gas circuit breaker has been studied in this study to improve efficiency of interrupting performance of short line fault(SLF). Hot gas flows of gas circuit breaker have been simulated to evaluate interruption performance using CFD. Design parameters such as various types of expansion chamber and nozzles are suggested by using simulation results. Simulated results and experimental ones are compared with previous (ones that of in under development and with capacitor) GCB. Modified new shape of an expansion chamber and nozzle has been suggested to improve the efficiency of gas flow and to provide guidelines for designing self-blast breaker with a higher interruption capability.