Meminimalkan biaya pengendalian korosi pada tangki timbun avtur dengan menggunakan serat rami (Boehmeria nivea) di Depot Pengisian Pesawat Udara Yogyakarta International Airport = Reducing corrosion control cost of avtur storage tanks using ramie fiber (Boehmeria nivea) at Yogyakarta International Airport Aircraft Refuelling Depot