As the first facility of VLBI observation, KVN (Korean very long baseline interferometer network) is consists`of three radio observatories, which sites are KVN Yonsei, KVN Ulsan and KVN Tamna. In each radio`observatory, more than ten Tera Bytes of data is produced during VLBI observation. But in traditional method,`this massive VLBI (very long baseline interferometer) data recorded in magnetic tape or HDD is transferred to`correlation center by transportation, which cause much loss of time and research products. To overcome this`problem, e-VLBI connecting each radio observatory and correlation center with high speed network was`appeared, and we are now design this concept in KVN by using KREONET (Korea Research Environment`Open NETwork). In this paper, we discuss the methods to transfer VLBI data from radio observatory to`correlation center efficiently. As part of an solution to improve the performance of data transfer, we especially`discuss system tuning for computer and network systems and stream based data transfer. Additionally, we`suggest upgraded data transfer system with this improvements.``