http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Development of fuzzy controller for inverter DC resistance spot welding using system identification
이희준,유지영 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
Adaptive Resistance spot welding (RSW) technologies have been developed and applied within the automotive industry to improve the weldability of automotive steels, including conventional and high strength steels. Almost all adaptive RSW systems require an inverter DC RSW system as a platform because such a system can generate various types of current waveforms effectively with higher control frequency than an AC RSW system. In this work, a fuzzy controller for an inverter DC RSW system that can control constant current and more complex current waveforms was developed as a platform for adaptive control of RSW. This study used System identification (SI) to model the inverter DC welding system effectively. To optimize the fuzzy controller for the SI model, fuzzy scaling factors were optimized using a genetic algorithm. To apply the scaling factor of the fuzzy controller with the SI model to a real system, the scaling factors were adjusted using response surface methodology.
이희준,도종대,김선신,박원경,전기천 한국해양과학기술원 2016 Ocean science journal Vol.51 No.4
Haeundae Beach represents Korean pocket beaches that are currently erosional and dominated by summertime typhoons. The decadal wave characteristics 9 km offshore of Haeundae Beach were analyzed using the WAM model that was validated through the 2007 wave observations. The wave statistics modelled for 1979–2007 indicates that the seasonal mean significant wave height (Hs) is highest (0.6–0.7 m) in summer due to typhoons, in contrast to the lowest (around 0.5 m) autumn analog. The wave direction is also pronouncedly seasonal with the principal bearings of SSW and NE in the summer and winter seasons, respectively. The WAM results additionally show that the Hs has gradually increased over the region of Haeundae Beach since 1993. Beach profiling during June–November 2014 shows the opposite processes of the typhoon and fair-weather on beach sands. During a typhoon, foreshore sands were eroded and then accumulated as sand bars on the surf zone. In the subsequent fair-weather, the sand bars moved back to the beach resulting in the surf-zone erosion and foreshore accretion. A total of 5 cycles of these beach-wide sand movements yielded a net retreat (up to 20 m) of the shoreline associated with large foreshore erosion. However, the surf zone only slightly accumulated as a result of the sand cycles. This was attributed to the sand escape offshore from the westernmost tip of the beach. The present study may provide an important clue to understanding the erosional processes in Haeundae Beach.