OPTIMIZATION OF PARAMETERS IN MEWMV AND MEWMA CONTROL CHARTS FOR CLEAN WATER QUALITY CONTROL AT PP KRAKATAU TIRTA GRESIK - Hafiyusholeh, Moh.; Khaulasari, Hani; Firmansyah, Fery; Ulinnuha, Nurissaidah (BAREKENG: Jurnal Ilmu Matematika dan Terapan, 2025)