Min Gyun Chung, Dai-Hong Kim, Hyun Myoung Lee, Taewoo Kim, Jong Ho Choi, Dong kyun Seo, Ji-Beom Yoo, Seong-Hyeon Hong, Tae Jung Kang and Yong Hyup Kim, “Highly sensitive NO2 gas sensor based on ozone treated graphene”, Sensors and Actuators B:Chemical, 166-167 (2012) 172-176