Direct Synthesis of Carbon Nanotube Field Emitters on Metal Substrate for Open-Type X-ray Source in Medical Imaging oleh Amar Prasad Gupta, Sangjun Park, Seung Jun Yeo, Jaeik Jung, Chonggil Cho, Sang Hyun Paik, Hunkuk Park, Young Chul Cho, Seung Hoon Kim, Ji Hoon Shin, Jeung Sun Ahn, Jehwang Ryu