Investigation on the effect of varying bubble size and location in electrical resistance tomography using conducting boundary strategy by Ridzuan Aw., Suzanna, Azimi, Farah Hanan, Syafie, Lia Safiyah, Abdul Rahim, Ruzairi, Abd. Wahab, Yasmin, Shuhaimi, Nurain Izzati, Raja Aris, Raja Siti Nur Adiimah, Ahmad, Ida Laila