1. DiFX at KASI Jongsoo Kim and Taehyun Jung Korea Astronomy and Space Science Institute http://jskim.kasi.re.kr/difx

2. YonseiUlsanTamna Korean VLBI Network - 2 -  3 × 21m Antennas  Maximum Baseline : 480 km  4 Channel (22/43/86/129 GHz), LCP/RCP  Simultaneous Observing System  Multi-Frequency Phase Referencing  Correlators: Daejeon(HW), DiFX(SW )

3. 22/43/86/129 GHz Receivers - 3 -

4. Performance tests East Sea Korea : KVN antenna Yonsei (Seoul), Ulsan, Tanma (Jeju) Japan : VERA antenna Mizusawa, Ishigaki, Iriki,Ogasawara 1.4 mas@22GHz 0.7 mas@43GHz

5. Improved image (22GHz) of M87 by KVN+VERA Total flux : 1.18 Jy Peak flux : 1.04 Jy/beam Image rms : 4 mJy/beam Total flux : 1.55 Jy Peak flux : 1.08 Jy/beam Image rms : 2 mJy/beam

6. Daejeon Correlator@KJCC

7. DiFX system one difx server: 16 cores (E5-2690), 64GB memory, CentOS 6.3 Storage: 120TB+80TB RAID 6, direct attached to server Mark5 unit: Mark 5B+(SDK8.3), 5C(SDK9.2), direct connection to server with 1GE

8. Operations Just started normal operations for KVN only following standard procedure –Fuse or mk5cp –vex2difx –calcif2 –mpifxcorr –difx2mark4, fourfit –difx2fits

9. Example

10. Performance mk5cp: ~ 0.51 Gbit/sec mpifxcorr with 16 cores: ~24 hours correlation time for a 12 hour 1Gbps observation with 3 KVN antennas

11. Future Plan “native” Mark5 correlation infiniband upgrade Correlation for KVN+VERA –Require copy of VERA 2000 tape to Mark 5 diskpack or storage