Erratum: Simulation on a photocathode-based microtron using a 3D PIC code

One affiliation of Sunjeong Park was omitted. It should be added as “Department of Physics, Kyungpook National University, Daegu 702-701, Korea”. Affiliation of Eun-San Kim had a typo. It should be corrected as “Department of Physics, Kyungpook National University, Daegu 702-701, Korea”.