In this paper, we introduce the performance evaluation and development of Raw VLBI Data Buffer(RVDB) system for the synchronized playback processing of observed data in Korea-Japan Joint VLBI Correlator(KJJVC). The high-speed correlation processing system is under development so that the radio data obtained with 8192 channels and 8 Gbps speed from 16 stations will be able to be processed. When the recorded data of each station are played to correlator, the time synchronization of each station is very important because the correlator should process the data obtained with same time and condition. There are many types of recorder systems in the East Asia VLBI Network (EAVN). Therefore it is required to prepare the special time synchronized playback processing system to synchronize the time tag of observed data. The developed RVDB system consists of Data Input Output(DIO), 10GbE switch, and Disk Data Buffer(DDB). It can record the data with maximum 2 Gbps speed, and can play back the data to correlator with nominal 2 Gbps speed. To enable to play back the data of different playback system to the correlator, we developed the high-speed time synchronized playback processing system. We carried out the experiments of playing back and correlation for gigabit correlator and VCS trial product so as to confirm the performance of developed time synchronized playback processing system. In case of online and offline playing back experiment for gigabit correlator, we confirmed that the online and offline correlation results were the same. In case of playing back experiment for VCS trial product, we verified that the wide band and narrow band correlation results were also the same. Through the playing back experiments of RVDB system, the effectiveness of developed RVDB system was verified. In this paper, the system design, construction and experimental results are shown briefly.

ABSTRACT
1. 서론
2. 한일공동VLBI상관기 개발
3. 동기재생처리 시스템
    3.1 DIO(Data Input Output)
    3.2 DDB(Disk Data Buffer)
    3.3 RVDB 시스템의 동작과 데이터 흐름
4. 실험결과
5. 결론
참고문헌

• 오세진(한국천문연구원) | SE-JIN OH (Korea Astronomy & Space Science Institute)
• 노덕규(한국천문연구원) | DUK-GYOO ROH (Korea Astronomy & Space Science Institute)
• 염재환(한국천문연구원) | JAE-HWAN YEOM (Korea Astronomy & Space Science Institute)
• 정현수(한국천문연구원) | HYUN-SOO CHUNG (Korea Astronomy & Space Science Institute)
• 이창훈(한국천문연구원) | CHANG-HOON LEE (Korea Astronomy & Space Science Institute)
• 김광동(한국천문연구원) | KWANG-DONG KIM (Korea Astronomy & Space Science Institute)
• 김효령(한국천문연구원) | HYO-RYOUNG KIM (Korea Astronomy & Space Science Institute)
• Tmoaki Oyana(일본국립천문대)
• Noriyuki Kawaguchi(일본국립천문대)
• Kensuke Ozeki(Elecs Industry Co. Ltd.)