• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.20-28
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• 2011

The electro-optical payload of a low-earth orbit satellite is thermally decoupled with the bus, which supports a payload for a mission operation. The payload has a cooling unit of FPA(Focal Plane Assembly) which has a thermal behavior increasing its temperature instantly during an operation in order to dissipate a waste heat into the space. The FPA cooling unit should include a radiator and heatpipes with a sufficient performance in worst hot condition, and a heater design to maintain its temperature above a minimum allowable temperature in the worst cold condition. In this paper, we analyzed the thermal requirements and the heater design constraints from the thermal analysis results for the current thermal design of the FPA cooling unit and the design elements of the better heater design were found.

• Korean Journal of Remote Sensing
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• v.24 no.6
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• pp.591-603
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• 2008

Satellite performance can be evaluated by image quality. MTF(Modulation Transfer Fuction), SNR(Signal To Noise Ratio), GSD(Ground Sample Distance) etc. are important bias parameters to analyze image quality. It is necessary to estimate quality of satellite image in design stage. In this paper, the simulating method of satellite image quality, considering design, manufacturing, and operation, is proposed. The proposed method shall be used to estimate and restore quality of satellite image.

• Korean Journal of Remote Sensing
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• v.39 no.6_3
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• pp.1791-1799
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• 2023

The Korea Aerospace Research Institute is responsible for supplying and supporting the utilization of imagery data from the Arirang satellite series for organizations affiliated with the Government Satellite Information Application Consultation. Most of them primarily utilize optical imagery, and there is a relative lack of utilization of Synthetic Aperture Radar (SAR) imagery. In this paper, as part of supporting the use of SAR images, we investigated SAR intensity-based change detection algorithms and their use cases that have been researched to determine SAR intensity-based change detection algorithms to be developed in the future. As a result of the research, we found that various algorithms utilizing intensity difference, correlation coefficients, histograms, or polarimetric information have been researched by numerous researchers to detect and analyze change pixels and the applications of change detection algorithms have been studied in various fields such as a city, flood, forest fire, and vegetation. This study will serve as a reference for the development of SAR change detection algorithms, intended for utilization in the Government Satellite Information Application Consultation.

• ETRI Journal
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• v.30 no.6
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• pp.774-782
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• 2008

An operational orbit determination (OD) and prediction system for the geostationary Communication, Ocean, and Meteorological Satellite (COMS) mission requires accurate satellite positioning knowledge to accomplish image navigation registration on the ground. Ranging and tracking data from a single ground station is used for COMS OD in normal operation. However, the orbital longitude of the COMS is so close to that of satellite tracking sites that geometric singularity affects observability. A method to solve the azimuth bias of a single station in singularity is to periodically apply an estimated azimuth bias using the ranging and tracking data of two stations. Velocity increments of a wheel off-loading maneuver which is performed twice a day are fixed by planned values without considering maneuver efficiency during OD. Using only single-station data with the correction of the azimuth bias, OD can achieve three-sigma position accuracy on the order of 1.5 km root-sum-square.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.709-712
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• 2005

Ground processing for geostationary weather satellite such as GOES, MTSAT includes the process called image navigation. Image navigation means the retrieval of satellite navigational parameters from images and requires landmark detection by matching satellite images against landmark chips. For an automated preprocessing, a matching must be performed automatically. However, if match results contain errors, the accuracy of image navigation deteriorates. To overcome this problem, we propose the use of a robust estimation technique, called Random Sample Consensus (RANSAC), to automatically detect mismatches. We tested GOES-9 satellite images with 30 landmark chips. Landmark chips were extracted from the world shoreline database. To them, matching was applied and mismatch results were detected automatically by RANSAC. Results showed that all mismatches were detected correctly by RANSAC with a threshold value of 2.5 pixels.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.394-397
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• 2006

본 논문에서는 일본의 정지궤도 위성인 MTSAT(Multi-functional Transport Satellite)-1R의 HRIT/LRIT(High Rate Information Transmission/Low Rate Information Transmission) 데이터의 특성 및 오차를 분석하였다. HRIT/LRIT 데이터를 수신하여 영상을 추출하고, 추출한 영상에 ITU(International Telecommunication Union)의 Space Radiocommunications Stations(이하 SDS) CD에 있는 Map 데이터를 겹쳐서 실제 해안선과의 차이를 계산하였다. 분석을 위하여 10일간의 HRIT/LRIT 수신 데이터를 사용하였고 분석한 결과 MTSAT-1R 위성의 HRIT VIS 영상의 평균오차는 Line 4.42 Pixel, Column 0.66 Pixel, LRIT IR1 영상의 평균오차는 Line 1.05 Pixel, Column 0.19 Pixel인 것을 알 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.425-430
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• 1991

For satellite orbit determination, a satellite (K-3H) which is affected by the earth's gravitational field and the earth's atmospheric drag, the sun, and the moon is chosen as a dynamic model. The state vector include orbit parameters, uncertain parameters associated with perturbations and tracking stations. These perturbations include gravitational constant, atmospheric drag, and jonal harmonics due to the earth nonsphericity. Early orbit was obtained with given the predicted orbital parameter of the satellite. And orbit determination, which is applied to Extended Kalman Filter(EKF) for real time implementation , use the observation data which is given by satellite tracking radar system and then orbit estimation is accomplished. As a result, extended sequential estimation algorithm has a fast convergence and also indicate effectiveness for real time operation.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.58-62
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• 2014

This paper we introduce the satellite communication system consist of redundant central station with management module for increase the stability of the satellite link. Configuration of redundant central station in satellite communication system can minimize the service interruption due to unstable link or some module error. According to this, we expect to ensure efficient use of technology for the next-generation VSAT services and broadcasting services.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.169-180
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• 2019

In this study, a batch least square estimator that utilizes optical observation data is developed and utilized to determine geostationary orbits (GEO). Through numerical simulations, the effects of error sources, such as clock errors, measurement noise, and the a priori state error, are analyzed. The actual optical tracking data of a GEO satellite, the Communication, Ocean and Meteorological Satellite (COMS), provided by the optical wide-field patrol network (OWL-Net) is used with the developed batch filter for orbit determination. The accuracy of the determined orbit is evaluated by comparison with two-line elements (TLE) and confirmed as proper for the continuous monitoring of GEO objects. Also, the measurement residuals are converged to several arcseconds, corresponding to the OWL-Net performance. Based on these analyses, it is verified that the independent operation of electro-optic space surveillance systems is possible, and the ephemerides of space objects can be obtained.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.150-158
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• 2013

In Korea, the official monitoring of the atmospheric re-entry of satellites or space debris was initiated by the first operation of a re-entry situation analysis team for the 'Cosmos 1402' of the Soviet Union, which main body re-entered on January 23, 1983 and radio active core re-entered on February 7, 1983. After this incident, a task force team consisting Korea Astronomy and Space Science Institute (KASI), Korea Aerospace Research Institute (KARI) and other related institutes operated a situation monitoring group under the supervision of the Ministry of Science and technology (MOST) for the controlled re-entry of the Russian 'Mir' space station in 2001. The re-entry of the upper atmospheric weather satellite 'UARS' of United States had been monitored and analyzed by KASI on September 24, 2011. As the re-entry of the space object has been frequently occurred, the government officials and the experts from MEST (Ministry of Education, Science and Technology), KASI, KARI had an urgent official meeting to establish a satellite re-entry monitoring room in KASI and to give an operational authority to KASI in September 14, 2011. Under this decision, the satellite re-entry monitoring room in KASI has successfully executed the monitoring, data analyzing, official reporting, media contacting, and public announcing for the German satellite 'Roentgen' in October 2011, Russian space explorer 'Phobos-Grunt' in January 2012, Russian satellite 'Cosmos 1484' in January 2013, and European geodetic satellite 'GOCE' in November 2013 with the support from the Korean Air Force and KARI.