• Journal of Astronomy and Space Sciences
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• v.33 no.2
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• pp.137-146
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• 2016

The correlation between meteorological data collected at the optical wide-field patrol network (OWL-Net) Station No. 1 and the seeing of satellite optical observation data was analyzed. Meteorological data and satellite optical observation data from June 2014 to November 2015 were analyzed. The analyzed meteorological data were the outdoor air temperature, relative humidity, wind speed, and cloud index data, and the analyzed satellite optical observation data were the seeing full-width at half-maximum (FWHM) data. The annual meteorological pattern for Mongolia was analyzed by collecting meteorological data over four seasons, with data collection beginning after the installation and initial set-up of the OWL-Net Station No. 1 in Mongolia. A comparison of the meteorological data and the seeing of the satellite optical observation data showed that the seeing degrades as the wind strength increases and as the cloud cover decreases. This finding is explained by the bias effect, which is caused by the fact that the number of images taken on the less cloudy days was relatively small. The seeing FWHM showed no clear correlation with either temperature or relative humidity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.805-808
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• 2005

This paper is a study on an optical bench satisfying stiffness and thermal pointing error requirements for LEO earth observation satellite. According to shape and stiffness requirements, optical bench type 1 is designed. Because type 1 does not satisfy the thermal pointing error requirement, an optical bench type 2 is suggested. Although the type 2 has better results than type 1, it still does not meet the thermal pointing error requirement. Using the results of optical bench type 1&2, the optical bench type 3 is finally designed, which satisfies both the stiffness and thermal pointing error requirements.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.76.1-76.1
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• 2019

After the first identification of electromagnetic counterpart of gravitational wave source (GW170817), era of multi-messenger astronomy has begun. For specifying coordinate, magnitude, and host galaxy information, optical follow-up observation of GW source becomes important. The O3 run of LIGO / VIRGO started after April 2019. We present searching strategy of GW optical counterpart using the KMTNet. By performing tiling observation of high probability area in GW localization map, we expect to observe early light-curve of GW optical counterpart. We will also present observation result for three gravitational wave events of binary black hole mergers. After identification of optical counterpart, we will study collision mechanism, progenitor, and characteristics of host galaxy using observation data of GW source.

• The Bulletin of The Korean Astronomical Society
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• v.27 no.2
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• pp.58-58
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• 2002

• Journal of the Korean Ceramic Society
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• v.23 no.2
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• pp.64-70
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• 1986

In this investigation x-ray diffraction method was mainly studied for quantitative analysis of clinker mineral composition. And also optical microscopic observation and Bogue calculation method were applied to compare with the x-ray diffraction method. In the procedure of x-ray diffraction analysis graphite monochromator automatic divergence slit and spinner for sample holder were used for minimizing the error due to the operation of the equipment. Especially the separation of overlapped peaks were proceeded by micro-processor automatically. The results of x-ray diffraction method for synthesized clinker were consistent with the Bogue value and the results of optical microscopic observation. However the results of quantitative analysis of mineral composition or commercial clinker containing solid solution of minor component were different from the Bogue value. On the other hand they agreed reasonably well with results of the optical mic-roscopic observation.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.28-29
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• 2001

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.207-210
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• 2005

In this paper, technical issues for an optical bench of high precision LEO Earth observation satellite are described. The optical bench should be stable for thermal and dynamic environment. In this point of view, an intermediate type of optical bench is developed. Thermal deformation analysis and modal analysis are performed for two types of FE model. Modal test are performed to verify the analysis results. The test results fit well the analysis results.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.53.3-54
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• 2021

We present optical follow-up observation results of three binary black hole merger (BBH) events, GW190408 181802, GW190412, and GW190503 185404, which were detected by the Advanced Ligo and Virgo gravitational wave (GW) detectors. Electromagnetic (EM) counterparts are generally not expected for BBH merger events, however, some theoretical models suggest that EM counterparts of BBH can possibly arise in special environments. To identify EM counterparts of the three BBH merger events, we observed high-credibility regions of the sky with telescopes of the Gravitational-wave EM Counterpart Korean Observatory (GECKO), including the Korea Microlensing Telescope Network (KMTNet). Our observation started as soon as 100 minutes after the GW event alert and covered roughly 29 - 63 deg2 for each event with a depth of 22.5 mag in R-band within hours of observation. No plausible EM counterparts were found for these events. Our result gives a great promise for the GECKO facilities to find EM counterparts within few hours from GW detection in future GW observation runs.

• The Bulletin of The Korean Astronomical Society
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• v.26 no.1
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• pp.38.1-38.1
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• 2001

• Journal of Astronomy and Space Sciences
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• v.26 no.1
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• pp.111-126
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• 2009

We used an optical observation system with a 0.6m wide-field telescope and 5 computers system in KASI (Korean Astronomy and Space Science Institute) for satellite optical observation. Optical data have errors that are caused by targeting, expose start time and end-point determination. Gauss method for initial orbit determination was tested using angle-only data simulated by KODAS. And suitable time span is confirmed for result which has minimum errors. Initial orbit determination results are proved that optical observation system in KASI is possible satellite tracking for a short period. And also through differential correction, initial orbit determination results are improved.