간행물
천문학논총 KCI 등재 Publications of the Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 연3회
- ISSN 1225-1534 (Print)2287-6936 (Online)
- 수록기간 1984 ~ 2023
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권호리스트/논문검색
Volume 18 (2003년 12월) 16건
1.
2003.12
구독 인증기관 무료, 개인회원 유료
In the framework of linear perturbation theory and linear approximation of spacetime anisotropy, we investigated the formulae for the CMBR temperature anisotropy and fluctuation spectrum which have their origin in the primordial tensor perturbations of the perturbed Bianchi type I universe model. The resulting formulae were compared with those of the flat Friedmann model.
4,000원
2.
2003.12
구독 인증기관 무료, 개인회원 유료
In the earlier papers we analyzed the axisymmetric, nonstationary electrodynamics of the central black hole and a surrounding thin accretion disk in an active galactic nucleus. Based on those papers we analyze the axisymmetric, nonstationary force-free black hole magnetosphere and the motion of the plasma. We concentrate on deriving the totally new equations for the entropy incrrease and the angular momentum, energy extraction of the black hole.
3,000원
3.
2003.12
구독 인증기관 무료, 개인회원 유료
In the earlier papers we analyzed the axisymmetric, nonstationary electrodynamics of the central black hole and a surrounding thin accretion disk in an active galactic nucleus. Based on those papers we analyze the axisymmetric, nonstationary black hole magnetosphere in this paper. We concentrate on deriving the ‘Grad-Shafranov equations’; both in the force-free and non-force-free cases. In the time-independent limit our equations naturally coincide with stationary equations as they should.
4,000원
4.
2003.12
구독 인증기관 무료, 개인회원 유료
The problem of the collapse of a self gravitating disk is here considered. We show self-similar solutions for the above problem under a modified viscous parameter. Surface density depends on rm in the inner region, where m is -1.6. Therefore growing central mass goes on without mass inflow to the system.
3,000원
5.
2003.12
구독 인증기관 무료, 개인회원 유료
In this paper, we have re-examined the relative sunspot numbers from June 1987 to December 2002 observed at Korea Astronomy Observatory. For this we determined conversion factors (K) for each year data to derive the relative sunspot numbers. The estimated conversion factor ranges from 0.57 to 1.09 and has a trend to decrease with time, which seem to depend on the several effects such as observational system, observation methods, and experience of an observer. Our analysis shows that the newly-determined relative sunspot numbers are in much better agreements with the international sunspot numbers than the previously-determined ones in which the conversion factors were determined only four times. This result implies that we should determine the conversion factor for each year data. From these investigations, we also identified one and half solar cycles form our relative sunspot number.
4,200원
6.
2003.12
구독 인증기관 무료, 개인회원 유료
We have developed a seeing monitoring system and measured seeing variation of the Bohyunsan Optical Astronomy Observatory (BOAO) and the Sobaeksan Optical Astronomy Observatory (SOAO) using a small telescope system. Our seeing monitoring system is similar to the differential image motion monitor (DIMM) installed at the ESO. The ooly difference between the BOAO and the SOAO seeing monitoring system is a detector system, a video camera at the BOAO and ST-4 camera at the SOAO. We confirmed that the seeing monitoring system at the SOAO can measure average seeing size inspite of its simple detector system. From the BOAO seeing measurement, we found that the seeing size changes fast.
We expect that our seeing monitoring system could be used for real time seeing monitoring after some improvement, and the data to be obtained would be very useful when we build adaptive optic system in the future.
4,000원
7.
2003.12
구독 인증기관 무료, 개인회원 유료
Korean Astronomical Data Center (KADC, http://kadc.kao.re.kr) in Korea Astronomy Observatory (KAO) has constructed an archive of Bohyunsan Optical Astronomy Observatory (BOAO) 1.8m telescope data. The archive is consisted of photometric (1KCCD, 2KCCD) and spectroscopic data of 400GB amount for the period of 1997 to 2002,and the first web service is made of the data from 1997 to 2001. In the search page, primary search criterion of object name or coordinates is used. Users can also refine the search criteria using parameters such as observation date, observer(s), data type, and/or instrument. The data identified from the search can be uploaded to the FTP site for further downloading in FITS format. This archive is the first DB of astronomical data made in Korea.
4,000원
8.
2003.12
구독 인증기관 무료, 개인회원 유료
This paper is the research and development including the system design and the prototype system building of the 400MHz wide-band digital autocorrelation spectrometer system for radio astronomy observation, which will be used as back-end signal processing unit of the Dual channel SIS receiver at Taeduk Radio Astronomy Observatory. So in this paper, we performed development of the high speed digitizing sampler, the circular memory buffer, and the correlator module for the 400MHz wide-band digital autocorrelator. This developed system will be use at TRAO after the housing and some calibration.
4,000원
9.
2003.12
구독 인증기관 무료, 개인회원 유료
In 2002, a new solar spectroscopic system with the Coelostat type has been installed at Korea Astronomical Observatory. It was designed to observe solar spectra in the range from 3000 to 8000 Å with the spectral resolution of 1 Å/mm. The system is composed of a 40cm diameter Coelostat with 9m focal length, spectroscopic system with 600groove/mm grating, and a IK × IK CCD detector. By developing observational softwares for this system, we have successfully observed solar Ha spectra. In this paper, we development of telescope control and observational softwares.
4,000원
10.
2003.12
구독 인증기관 무료, 개인회원 유료
A CCD camera for the BOES (Bohyunsan Observatory Echelle Spectrograph) has been developed. The camera consists of a 2048 × 4096 format CCD, a SDSU Gen-I CCD controller, and a continuous flow cryostat (CFC) designed by the ESO. In order to control the CCD under SDSU Gen-I controller, the voltage level of all the biases and clocks were lowered by -6V. The CFC showed cooling time of about 10 hour, after which the chip temperature settled down with variation less than ±1°C. The final chip temperature is around -105 °C with the setting value for the CFC as -170 °C
4,000원
11.
2003.12
구독 인증기관 무료, 개인회원 유료
The characteristics of the BOES (Bohyunsan Observatory Echelle Spectrograph) CCD camera is presented. In order to get optimum gain and readout noise of the CCD, we examine the variation of the gain and readout noise by changing the value of output drain voltage of the CCD and measuring the gain using transfer curve, which is defined as the plot of variance versus mean exposure level of a homogeneous light onto the CCD surface. The gain and readout noises are optimised to be 0.5e −/ADU and 3e−, which is good for highest signal-to-noise ratio and contrast for the low light level characteristics of the BOES. We also measure the dark count of the CCD by getting five dark images with 3600 seconds exposure time. The mean dark count from median stacked dark images is essentially zero. A table of positions of defected pixels is also presented.
4,000원
12.
2003.12
구독 인증기관 무료, 개인회원 유료
We tested the characteristics of the newly made Long Slit Spectrograph (LSS) of the BOAO which replaced the Medium Dispersion Spectrograph (MDS) in the year of 2003. Performance test results on the spectrogram shift by gravity direction variation, slit illumination function, efficiency and the precision of the radial velocity measurements show the capabilities of the LSS are much improved in every respect comparing with those of the MDS.
4,000원
13.
2003.12
구독 인증기관 무료, 개인회원 유료
FIMS (Far-ultraviolet IMaging Spectrograph) is the main payload of STSAT-1 satellite which was successfully launched on September 27, 2003. The optical system of FIMS consists of two sets of parabolic cylinder mirror, slit, ellipsoidal reflection grating, and baffle system. We designed two types of baffle system for the FIMS: FOV baffle and order baffle. FOV baffle in the mirror house controls the field of view, and the order baffle in the vacuum box blocks the rays reflected rays by different orders.
4,000원
14.
2003.12
구독 인증기관 무료, 개인회원 유료
WRC-03 was held between 9 June and 4 July 2003 in Geneva, Switzerland. Over 2,200 delegates from 138 ITU Member States attended the Conference. The delegates considered some 2,500 proposals, and over 900 numbered documents related to 50 agenda items. The final output of the Conference consists of 527 pages of new and revised text of the Radio Regulations. This paper provides some details about the outcome of the radio astronomy related issues at the WRC-03 Conference. It is divided into two part: a) Agenda item1.8.2 and b) Agenda item 1.32, related to radio astronomy. Relevant extracts from the Final Acts of WRC-03 are given in the Appendix.
Agenda item 1.8.2 was one of the most controversial Agenda Items at WRC-03. Studies were carried out within ITU-R TG 1/7 for the last three years; the results of these studies are summarized in Recommendation ITU-R SM.1633. The Conference adopted a new footnote (5.347A), that calls for the application of Resolution 739 (WRC-03) in the 1452-1492 MHz, 1525-1559 MHz, 1613.8-1626.5 MHz, 2655-2670 MHz, 2670-2690 MHz and 21.4-22.0 GHz bands.
Agenda item 1.32 is to consider technical and reglatory provisions concerning the band 37.5-43.5 GHz, in accordance with Resolutions 128 (Rev.WRC-2000) and 84 (WRC-2000). WRC-03 reviewed and adjusted the New footnotes 5.551H and 5.551I cover the protection of radio astronomy observations in the 42.5-43.5 GHz band from unwanted emissions by non-geostationary (5.551H) and geostationary (5.551I) FSS and BSS systems, respectively.
4,600원
15.
2003.12
구독 인증기관 무료, 개인회원 유료
Most radio astronomy issues at WRC-03 (World Radiocommunication Conference-03) revolved around satellite downlink allocations, particularly to NGSO (Non-Geostationary Satellite Orbit) satellite systems, in bands adjacent to or close to a radio astronomy frequency band.
Out of a total of 50 agenda items, ten were of interest to radio astronomers. This paper provides some details about the important outcome of the radio astronomy related issues at the WRC-03.
6,000원
16.
2003.12
구독 인증기관·개인회원 무료
