• Journal of Astronomy and Space Sciences
• /
• v.22 no.3
• /
• pp.223-232
• /
• 2005

New BVR CCD light curves of the low mass ratio contact binaries, V410 Aur and V776 Cas, were observed with the 61 cm reflector and a 2K CCD camera at the Sobaeksan Astronomical Observatory. The absolute dimensions of the low mass ratio contact binaries, V410 Aur and V776 Cas, were obtained using WD program from the published spectroscopic and newly observed photometric data. The evolutionary status of this type of binary system including V410 Aur and V776 Cas has been considered. We reconfirmed that the primary stars of the low mass contact binary system were located on the TAMS and secondary stars were located under the ZAMS in H-R diagram.

• Journal of Astronomy and Space Sciences
• /
• v.22 no.3
• /
• pp.311-328
• /
• 2005

This study was to understand the components that influence preservice elementary teachers' mental models about 'astronomical phenomena' such as the Seasons of the year, and the Lunar Phases of the month. We selected university of education students among whom 23 were in the second you. The data collected from the paper-pencil test and individual interview with students. The results of this study show that the students had apparent synthetic Mental models, and that the distance theory, and occultation theory had most important effects on their Mental Models. It can be said that preservice elementary teachers' initial mental models of the' astronomical phenomenon' have their origin in their belief sets (specific theory) related to 'astronomical phenomenon', on the basis of which they can interpret their observations and cultural information with the constraints of a naive framework of physics. The structures and possible sources of their mental models for overcoming these synthetic mental models were also discussed.

• Journal of Astronomy and Space Sciences
• /
• v.19 no.1
• /
• pp.7-18
• /
• 2002

Interstellar cabon monoxide and its isotopes were observed with the 13.7m radio telescope of the Daeduk Radio Astronomy Observatory toward Orion Molecular Cloud-1 (OMC-1). We derive the excitation temperature, optical depth, column density, and isotopic abundance ratios from the observed lines of $^{12}CO,^{13}CO,\;and\;C^{18}O$ inside of the region of $11'{\times}11'$. The optical depths of $^{13}CO$ were obtained to be 0.1~0.4, while those of $C^{18}O$ to be 0.01~0.03. The isotopic ratios $^{12}C/^{13}C$ were also estimated to be 2~60. We could not find the radial isotopic ratio $^{12}C/^{13}C$ gradient in the OMC-1.

• Journal of Astronomy and Space Sciences
• /
• v.23 no.3
• /
• pp.237-244
• /
• 2006

We produced the electron density distribution in the ionosphere over South Korea using the data from nine permanent GPS (Global Positioning System) stations which have been operated by KASI (Korea Astronomy and Space Science Institute). The dual-frequency GPS receiver data was used to precisely estimate the electron density in the ionosphere and we obtained the precise electron density profile based on two-dimensional TEC (Total Electron Contents). We applied ART (Algebraic Reconstruction Technique), which is one of the most commonly used algorithms to develop the tomography model. This paper presented the electron density distribution over South Korea with time. We compared with the electron density profiles derived from the GPS tomography reconstruction, Ionosonde measurement data obtained by observations, and the IRI-2001 values. As a result, the electron density profile by GPS reconstruction was in excellent agreement with the electron density profile obtained by Ionosonde measurement data.

• Journal of Astronomy and Space Sciences
• /
• v.18 no.3
• /
• pp.175-190
• /
• 2001

We investigated population of the elliptical galaxy NGC 4649 using the spectral synthesis technique based on the linear program in the spectral regions between $3160\AA$to $10800\AA$. We used the spectral data of stars obtained by Gunn & Striker (1983), and the integrated spectrum of NGC 4649 observed by Bertola et al. (1982). Among four models with different main sequence turn-off points, G8-K0V main sequence turn-off model is best fitted to the integrated spectrum of NGC 4649. We also found that super metal rich K giants are needed to describe the absorption lines in the long wavelength regions of integrated spectrum of NGC 4649. The mass to absolute light ratio obtained from the spectral synthesis is ~ 20 similar to those calculated dynamically.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.3
• /
• pp.267-282
• /
• 2008

The GNSS (Global Navigation Satellite System) signal is delayed by the neutral atmosphere at the troposphere, so that the delay is one of major error sources for GNSS precise positioning. The tropospheric delay is an integrated refractive index along the path of GNSS signal. The refractive index is empirically related to standard meteorological variables, such as pressure, temperature and water vapor partial pressure, therefore the tropospheric delay could be calculated from them. In this paper, it is presented how to generate meteorological data where observation cannot be performed. KASI(Korea Astronomy & Space Science Institute) has operated 9 GPS (Global Positioning System) permanent stations equipped with co-located MET3A, which is a meteorological sensor. Meteorological data are generated from observations of MET3A by Ordinary Kriging. To compensate a blank of observation data, simple models which consider periodic characteristics for meteorological data, are employed.

• Journal of Satellite, Information and Communications
• /
• v.8 no.3
• /
• pp.32-40
• /
• 2013

The Boltwood Cloud Sensor is meteorological sensor that is used to estimate an amount of clouds in the sky. This sensor will be installed for OWL(Optical Wide-field patroL) telescope and observatory system of Korea Astronomy and Space Science. Before applying this sensor to an observatory system, we performed test observations at Chungbuk University Observatory at Jincheon, Chungbuk. During the test run, a significant correlation between air temperature difference and the number of visible stars recorded in the CCD frames has not been found. This preliminary result can be attributed to test environment of the observation and our lack of knowledge on calculation algorithm as well as the hardware system of the Boltwood Cloud Sensor.In this paper, we present the procedure and the result of the performance test employing the cloud sensor.

• Journal of Astronomy and Space Sciences
• /
• v.20 no.4
• /
• pp.239-248
• /
• 2003

We completed the light curves of near-contact binary system AX Dra for 11 nights from March 2001 to May using the 61-cm reflector and VR filters at Sobaeksan Optical Astronomy Observatory. From our observations, seven new times of minimum light (three timings to. primary eclipse, four. for. secondary) and the light elements consistent with recent observations were determined. Using the Wilson-Devinney binary code and the q-search method, we analyzed our VR light curves for various Roche configurations and mass ratios. As the results, we found the eclipsing binary AX Dra to be the FO Vir-type near-contact binary system interpreted as a detached or a semi-detached system, with the secondary filling its Roche lobe and the primary almost. Unlike the statistical study(Shaw 1994) of the FO Vir-type near-contact binary system, our VR light curves showed the O'Connell effect of all the same type and it's dimensions was about $0^{m}.008$.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.1
• /
• pp.61-70
• /
• 2008

As the second step of the real time monitoring system of the solar radio disturbance, we constructed a 2.8 GHz radio receiver with 500 MHz bandwith. Using the control and observing system (Yoon et al. 2004), we observed the Sun, and found some frequencies, which disturb the Solar radio flux to be observed. DMB and aiport control frequencies are identified as responsible for this disturbance. As well as the testing the receiver, the measurment of the radio environment at 2.8 GHz with 500 MHz bandwith are carried out around Chungbuk National University. In fact, the radio power of the two frequencies, 2.649 GHz and 2.874 GHz is so high that we can not observe the Solar radio signal at 2.8 GHz. We report some results of this measurment and suggest the method to overcome this problem. We conclude also that the frequecies, which are important for the astronomy, should be protected in the future.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.94.1-94.1
• /
• 2012

천리안위성은 우리나라 최초의 정지궤도복합위성(COMS: Communication, Ocean, and Meteorological Satellite)으로 2010년 6월 27일, 남미 기아나 쿠루기지에서 아리안-5 로켓에 의해 발사된 후 동경 128.2도, 적도 상공 약 35,800 km 고도의 정지궤도에 안착되었다. 이 후 궤도상시험 기간과 안정화 기간을 거쳐 2011년 4월 1일, 기상청은 위성자료 서비스를 시작하였다. 천리안위성의 기상영상기는 한반도 주변의 기상변화와 전 지구적 기후 변화 및 대기 운동을 감시하기 위해 실시간 관측 및 전송 시스템을 갖춘 탑재체이다. 이 기상영상기는 하루 8번의 지구 반면 영역과 각각 80번 내외의 북반구 및 한반도 영역을 관측하며, 이 자료는 지상에서 복사보정과 기하보정을 거친 후 위성을 통해 다시 사용자에게 배포된다. 천리안위성 기상영상기는 쉼 없이 관측하고, 일정 시간 이내에 그 자료를 배포해야 한다. 이러한 자료서비스는 운영시스템의 장애나 자연현상에 의한 자료 미수신 혹은 미처리가 발생할 경우 운영 결과 및 성과에 영향을 미친다. 이와 같은 장애에 대비해 국가기상위성센터는 이중화된 시스템을 구축했으며, 자료 백업 부기관으로서 한국항공우주연구원과의 사이트 이중화도 시행하고 있다. 그러나 정지궤도에 있는 위성과 태양 및 지구의 역학적인 관계에 따라 태양 전파 잡음의 영향인 태양간섭과, 위성 태양전지판 충전 장애를 일으킬 수 있는 위성식, 그리고 위성 자정 주변에 발생할 수 있는 태양광 침입 및 산란광 영향 등은 미리 예측되어야 하며, 이 시기 운영 방안 마련과 사용자 공지 등의 조치가 수반되어야 한다. 국가기상위성센터는 춘 추분 시기에 발생하는 이러한 태양 영향을 예측하고 검증했으며, 이 시기 위성 및 지상국의 효율적인 운영방안을 마련하였다.