J.W. Ok \emph{et al.}, "A Diagnostics of Ion Beam from 28 GHz Electron Cyclotron Resonance Ion Source", in Proc. 3rd International Beam Instrumentation Conference, Monterey, CA, USA, paper WEPF12, pp. 561–564, ISBN: 978-3-95450-141-0, \url{http://jacow.org/IBIC2014/papers/wepf12.pdf}, 2014.