• Journal of Astronomy and Space Sciences
• /
• v.22 no.1
• /
• pp.1-12
• /
• 2005

The Korean VLBI Network (KVN) will open a new field of research in astronomy, geodesy and earth science using the newest three Elm radio telescopes. This will expand our ability to look at the Universe in the millimeter regime. Imaging capability of radio interferometry is highly dependent upon the antenna configuration, source size, declination and the shape of target. In this paper, imaging simulations are carried out with the KVN system configuration. Five test images were used which were a point source, multi-point sources, a uniform sphere with two different sizes compared to the synthesis beam of the KVN and a Very Large Array (VLA) image of Cygnus A. The declination for the full time simulation was set as +60 degrees and the observation time range was -6 to +6 hours around transit. Simulations have been done at 22GHz, one of the KVN observation frequency. All these simulations and data reductions have been run with the Astronomical Image Processing System (AIPS) software package. As the KVN array has a resolution of about 6 mas (milli arcsecond) at 220Hz, in case of model source being approximately the beam size or smaller, the ratio of peak intensity over RMS shows about 10000:1 and 5000:1. The other case in which model source is larger than the beam size, this ratio shows very low range of about 115:1 and 34:1. This is due to the lack of short baselines and the small number of antenna. We compare the coordinates of the model images with those of the cleaned images. The result shows mostly perfect correspondence except in the case of the 12mas uniform sphere. Therefore, the main astronomical targets for the KVN will be the compact sources and the KVN will have an excellent performance in the astrometry for these sources.

• Journal of Astronomy and Space Sciences
• /
• v.21 no.2
• /
• pp.121-128
• /
• 2004

As the first step of the real time monitoring system of the solar radio disturbance, we constructed the control system of the solar radio telescope. An 1.8m antenna built by Korean Astronomy Observatory has been used, and the observed radio flux is transformed to the digital signal by the powermeter. We have also developed a computer program CBNUART in order to control the telescope system and the powermeter. As the sun rises, the telescope begins to observe the sun, and ends the observation automatically at sunset. The CBNUART enables the telescope automatically to go to the position of the sunrise for the beginning the observation and come back to the setposition after the ending the observation at the sunset. An active tracking routine is adopted in order to improve the tracking accuracy of the control system, and we used an optical telescope equipped in front of the antenna for control test. The tracking test shows that our control system can track with the accuracy of arc seconds, and the 50 minute pointing test shows that the pointing accuracy of right ascension and declination are 1.12 and 0.08 arc minutes respectively.

• Journal of Navigation and Port Research
• /
• v.30 no.5 s.111
• /
• pp.363-367
• /
• 2006

The frequency band $10.5GHz\sim10.7GHz$ provides some of the best angular resolutions using many large and accurate radio telescopes. Developing high performance Bandpass Filter is needed for these equipments to receive low power signals from the space. In this paper, suggests Bandpass Filter for Radio Astronomy equipments. Designed by Microstrip Line for good pass characteristic and suppressing not necessary signals cause of using high frequency. Center frequency is 10.6 GHz and band width is 5% of Center frequency. Manufactured Bandpass Filter is suitable for Radio Astronomy Equipments. Bemuse it matches up to the result by simulate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2006.06b
• /
• pp.121-125
• /
• 2006

The frequency band $10.5GHz{\sim}10.7GHz$ provides some of the best angular resolutions that using many large and accurate radio telescopes. Developing high-performanced Bandpass Filter is needed for these equipments receive low power signals from the space. In this paper, Bandpass Filter for Radio Astronomy equipments is proposed. It is designed by Microstrip Line for good pass characteristic and suppressing unwanted signals. Center frequency is 10.6 GHz and band width is 5% of Center frequency. Manufactured Bandpass Filter is suitable for Radio Astronomy Equipments. Because the measured results agree well with the simulation results.

• Journal of the Institute of Convergence Signal Processing
• /
• v.10 no.4
• /
• pp.280-288
• /
• 2009

In this paper, we developed new time information recording module of VSI (VLBI Standard Interface) format by analyzing the Mark5B recorder control and operation software with 1Gbps speed, which is able to record the weak signal of space radio source, through the Korean VLBI Network (KVN). The control and operation software of high-speed recorder consists of 2 kinds of software, which is that it can operate RAID control board by controlling large capacity HDD drive and the network control and operation. Especially, core software in high-speed recorder is able to output the results after performing and analyzing the input command. Through the analysis of control and operation software, new time information recording module, which is needed to process the observed data for correlation, is developed. New developed time information recording module can record the time information together after checking the interrupt of 1PPS(Pulse Per Second) input signal when the observed data will be recorded. To verify the normal operation of the developed time information recording module, we performed the real observation test and confirmed the effectiveness of developed software through analyzing the recorded observation data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.8
• /
• pp.648-659
• /
• 2018

In this study, both the altitude error due to the refraction and the range error due to the delay in the ionosphere with respect to the frequency are extracted according to the radar elevation to analyze the effect of atmosphere on the space surveillance radar. To achieve this, the radio refractivity profile is modeled using the measured data from domestic weather stations. Then, the altitude-error due to the refraction is extracted using the ray tracing method, and the range error in the ionosphere is extracted according to the frequency. Further, considerations for radar design with respect to the radar error characteristics are discussed based on the abroad space surveillance radar and proposed domestic space surveillance radar. This analysis of the error characteristics is expected to be utilized for the determination of radar location, range of steering, and frequency in the space surveillance radar design.

• Aerospace Engineering and Technology
• /
• v.13 no.1
• /
• pp.184-192
• /
• 2014

In this paper, the lifetime of the artificial space objects in the LEO is analysed by using TLE data, which is provided by JSpOC. We observed the change of the number of space objects from 1957 and determined the reason of space debris generation. And then, we performed the analysis about present condition of space debris environment. The lifetime analysis includes a total of 11,792 artificial space objects and performed until the year 2050 by orbit propagation. We analyze the annual reentry frequency for the high RCS objects such as nonoperational satellites and rocket bodies, which have the possibility of earth ground impact through STK/Lifetime Tool for accurate and effective calculation. The results show that 9 payloads or rocket bodies will be decayed annually and 2 or 3 objects of total value have the possibility of ground impact. In addition, it is also shown that the 40% of a total analysed objects have the lifetime over 200 years.

• Bulletin of the Korean Space Science Society
• /
• 2009.10a
• /
• pp.25.2-25.2
• /
• 2009

한국천문연구원 한국우주전파관측망(Korean VLBI Network, KVN)에서 도입하여 시험운용중인 VLBI 상관서브시스템(VLBI Correlation Subsystem, VCS)은 한일공동 VLBI 상관기(Korea-Japan Joint VLBI Correlator, KJJVC)의 핵심 장비로서, 최대 16 관측국의 관측국 당 최대 8Gbps의 데이터를 처리할 수 있는 상관처리장치이다. VCS의 상관처리 결과는 총 4회선의 10GbE 광케이블을 통하여 UDP 프로토콜로 출력된다. 이 상관처리 결과는 광케이블 하나당 8개씩 총 32개의 상관 처리 블록(correlation block)으로 구성되며, 최대 출력속도는 1.4 GBytes/sec이다. 이 출력은 초고속 대용량 자료저장 시스템(Peta-scale Epoch Data Archive, PEDA)을 이용하여 저장하고 후속 자료처리를 위해 가공된다. PEDA는 총 4대의 고성능 자료 전송 및 저장 서버(writing server) 및 대용량 하드디스크 어레이로 구성된다. 상관처리 과정에 맞추어 PEDA의 writing 서버를 연계하여 제어하는 자료 전송 및 저장 제어 소프트웨어를 개발하였다. 이 소프트웨어는 핵심이 되는 전송 및 저장 프로세서와 이를 제어하는 제어프로세서로 구성된다. 전송 및 저장 프로세서는 개개의 상관 처리 블록에 대한 전송과 저장을 전담한다. 제어 프로세서는 총 32개의 상관 처리 블록을 처리하기 위하여 전송 및 저장 프로세스를 32개를 실행하고 각각의 상관 처리 블록에 해당하는 개별파라미터를 전달하는 전체적인 제어를 담당한다. 이 연구에서는 이 자료전송 및 저장 제어 소프트웨어의 설계 구성과 테스트 내용을 소개한다.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.54-54
• /
• 2012

한국 젊은 천문우주과학자들의 모임(Korea Young Astronomers Meeting, KYAM)과 일본 젊은 천문우주과학자들의 모임(Japan Young Astronomers Meeting, JYAM)은 지난 2006년부터 한-일 젊은 천문우주과학자들의 모임(Korea-Japan Young Astronomers Meeting, KJYAM-JKYAM)을 개최하고 있다. 이 모임은 학문 후속 세대로서 활발히 연구를 진행하고 있는 한국과 일본의 젊은 천문우주과학자들 간의 관계를 유지, 강화하여, 천문학 및 우주과학분야에서 많은 교류를 해오고 있는 양 국의 관계를 더욱 발전시켜 나가는 것이 목적이다. 제1회 KJYAM은 2006년 한국 경주에서 열렸으며, 그 후 2008년 일본 교토, 2009년 한국 과천, 2010년 일본 도쿄에서 진행되었다. 그리고 2012년 2월, 제 5회 KJYAM이 한국 연세대학교에서 2박 3일에 걸쳐 개최되었다. 이번 KJYAM에서는 일본 소속 1명의 SOC를 포함한 3명의 SOC와 1명의 초청 연사로부터 초청 강연이 있었고, 일본 소속 11명, 한국 소속 35명, 그리고 중국 소속 1명의 참석자들이 자신의 연구 성과를 발표하였다. 또한 경복궁 방문과 연세 KVN 전파망원경 견학을 통하여 한국의 오래된 고궁에서부터 가장 최신의 천문 시설까지 관람하는 기회를 가질 수 있었다. KYAM과 JYAM 두 모임은 이러한 KJYAM-JKYAM 모임을 지속함으로써, 양 국 젊은 천문우주과학자들의 친목 관계를 증진시킬 뿐만 아니라, 상호간의 공동연구 진행에 긍정적인 영향을 끼칠 것으로 기대하고 있다. 다음 JKYAM은 2013년 일본에서 개최될 예정이다.

• Journal of Space Technology and Applications
• /
• v.1 no.2
• /
• pp.160-177
• /
• 2021

The Solar and Space Environment Division of the Korean Space Science Society investigated the use and possession of ground and satellite observations and models of solar and planetary data operated by domestic research institutes and universities. Based on the findings, we would like to introduce observational instruments, data, and models in solar and interplanetary fields in this paper to improve understanding and use of each data and explore opportunities for interdisciplinary research. The ground and satellite observations, which require a lot of investment, were mainly held by research institutes (National Meteorological Satellite Center, Polar Research Institute, Korean Space Weather, Korea Astronomy and Space Science Institute and KAIST Satellite Research Institute), and model development was overwhelmingly carried out at Kyung Hee University. In solar and interplanetary fields, we introduce Fast Imaging Solar Spectrograph (FISS), neutron monitors, and the analysis models [for the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) and Hinode/X-Ray Telescope (XRT) observations] in nonequilibrium ionization state as representatives. Survey on solar and interplanetary fields can be downloaded from the website of the Korean Space Science Society (http://ksss.or.kr/). The paper makes know the importance of long-term and continuous management of space science-related materials, and hopes to contribute to enhancing the status of domestic space science data by utilizing locally produced data by various personnel participating in space science research.