Optimization Study on Turning Process by Using Taguchi-copras Method Do Duc Trung, Nguyen Huu Quang, Tran Quoc Hoang, Cao The Anh, Nguyen Hong Linh, Hoang Trung Kien, Do Thi Tam and Nguyen Anh Tuan E3S Web Conf., 309 (2021) 01010 Published online: 07 October 2021 DOI: 10.1051/e3sconf/202130901010