Perancangan sistem peringatan dini kebocoran gas dengan teknologi ultrasonik di area mike-mike platform pertamina hulu energi offshore north west java (ONWJ) = Early warning system design for the presence of gas leak with ultrasonik technology in mike-mike platform pertamina hulu energi offshore north west java (ONWJ) - Ihin Solihin, author (Fakultas Teknik Universitas Indonesia, 2010)