• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.40-50
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• 2003

The operational orbit evolution of the KOMPSAT-l over 3 years was analyzed. During LEOP, four orbit maneuvers were performed to obtain the optimized orbit and eight safe-hold modes happened. The effects of unpredictable occurrence of the safe-hold mode and the highest solar activity on the orbit evolution during the mission life were analyzed. The comparison of orbital elements between long-term predicted orbit and determined orbit from observed data was also performed. The operational orbit started from the optimized one was evolved within the boundary of the designed mission orbit except altitude and it was verified the sun-synchronous orbit was successfully maintained.

• Korean Journal of Remote Sensing
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• v.36 no.6_2
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• pp.1615-1627
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• 2020

The purpose of this study is to compare and analyze the performance of KOMPSAT-3 Digital Surface Model (DSM) made in overseas testbed area. To that end, we collected the KOMPSAT-3 in-track stereo image taken in San Francisco, the U.S. The stereo geometry elements (B/H, converse angle, etc.) of the stereo image taken were all found to be in the stable range. By applying precise sensor modeling using Ground Control Point (GCP) and DSM automatic generation technique, DSM with 1 m resolution was produced. Reference materials for evaluation and calibration are ground points with accuracy within 0.01 m from Compass Data Inc., 1 m resolution Elevation 1-DSM produced by Airbus. The precision sensor modeling accuracy of KOMPSAT-3 was within 0.5 m (RMSE) in horizontal and vertical directions. When the difference map was written between the generated DSM and the reference DSM, the mean and standard deviation were 0.61 m and 5.25 m respectively, but in some areas, they showed a large difference of more than 100 m. These areas appeared mainly in closed areas where high-rise buildings were concentrated. If KOMPSAT-3 tri-stereo images are used and various post-processing techniques are developed, it will be possible to produce DSM with more improved quality.

• Bulletin of the Korean Space Science Society
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• 2006.04a
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• pp.52-52
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• 2006

• Bulletin of the Korean Space Science Society
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• 2006.04a
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• pp.48-48
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• 2006

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.914-924
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• 2010

In this paper, results on the orbit analysis for the KOMPSAT-2 satellite using a real orbit data during the LEOP and normal mission lifetime are presented. In particular, the preparation and performance of an orbit operations during the LEOP is emphasized and the effects of space environments (i.e., Solar activity) on orbit evolutions are investigated comparing to those of the KOMPSAT-1 satellite. The summarized results in this paper would be an important reference to improve the stability and effectiveness of satellite operations during the LEOP and normal mission lifetime in case of LEO satellites such as successors of KOMPSAT-2 (i.e., KOMPSAT-3, KOMPSAT-3A, KOMPSAT-5).

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.48.2-48.2
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• 2009

아리랑위성 2호는 2006년에 발사되어 정상 운영 중이다. 아리랑 위성 5호와 아리랑위성 3호는 각각 2010년과 2011년에 발사될 예정이다. 아리랑위성 2호의 운영시스템은 하나의 위성을 운영하는 개념에 따라서 개발되었다. 그러나 아리랑위성 3호 운영시스템과 아리랑위성 5호 운영시스템은 다중위성운영 개념을 도입하여 개발되고 있다. 다중위성운영 개념이란 (1) 임무를 준비하고 수행하기 위해서 충분한 임무 요소, 시설 요소, 인원 및 운영절차를 확보한다. (2) 각각의 운영시스템은 독자적인 임무 요소, 시설 요소, 인원 및 절차를 소유하나 하위 상세 부분들은 다른 운영시스템과 공유된다. 다중위성운영의 경우에 장비, 서브시스템, 운영절차 등이 다를 수 있고, 독자적인 운영시스템 구성이기 때문에 운영이 복잡하고 운영비용이 많이 든다. 이 논문에서는 이러한 점을 개선시키기 위해서 다중임무운영 설계개념을 제시한다. 다중임무운영 개념은 (1) 임무를 준비하고 수행하기 위해서 최근 수정 및 변경된 임무 요소, 시설 요소, 인원 및 운영절차를 확보한다. (2) 최근 수정 및 변경된 임무 요소, 시설 요소, 인원 및 운영 절차는 이전 개발된 운영시스템이 수행하는 기능을 지원한다. 이러한 개념의 다중임무운영은 비슷한 임무와 기능을 가진 위성들이 같은 운영자와 조직에 의해서 운영될 때 잘 적용될 수 있다. 다중임무운영시스템은 각각의 임무에만 사용되는 모듈과 다른 임무와 공통으로 사용되는 모듈로 구성된다. 이러한 개념에 따라서 운영시스템을 개발하면 개발하기 위한 시간과 예산을 크게 감소시킬 수 있다. 또한, 발사 이후 운영의 편리, 운영인력의 효율적인 활용 및 유지보수의 편리성으로 인해서 운영 상황이 크게 개선된다.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.87-98
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• 2014

Generally there is a technical gap for the image data quality between from the satellite requirement values and from the users. After Cal/Val for KOMPSAT-3 had been done by Dec. 31, 2012, all requirements for KOMPSAT-3 image data quality have been validated, and then the normal operation of it started from Jan. 2013. In the normal period, the image data quality for the users has been defined and managed, and according to the result of it, the additional Cal/Val items have been doing. Cal/Val team and Processing team in KARI made the quality report (QR) for KOMPSAT-3 image data quality for the users, and have determined the quality level of KOMPSAT-3 product generated by Processing system (PMS; Product Management System) and managed the quality report for it. According to the result of the quality report, Cal/Val team defined six additional Cal/Val items, and has done five items of them and has been implementing the result of them into the Processing system.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.109-116
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• 2004

In a satellite time management system, the GPS-based clock synchronization technique[1] has the merits of precision time management by knowing the time difference or the error between the OBT(On Board Time) of the internal processors and GPS time every second. It can be realized employing the DPLL(Digital Phase Loop Lock) and FEP(Front End Processor) circuitry for the clock synchronization[2]. In this paper, a refined DPLL & FEP scheme is proposed to provide the precision, stability and robustness of the operation, which is to compensate the errors and noise of the GPS signal, and also to cope with the case when the GPS signal is lost due to several reasons. The simulation and HIL (Hardware In the Loop) test results using the FM(Flight Model) in the course of KOMPSAT-2(Korea Multi Purpose Satellite-2) design and development are illustrated to demonstrate the salient features of this methodology.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.92-97
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• 2005

In this paper, the performance of the KOMPSAT-1 GPS receiver on orbit was analyzed. OD (Orbit Determination) accuracy using GPS navigation solutions and GPS visibility were investigated with respect to the configuration of the GPS receiver. Indeed, the problem such as ‘3D Fix Loss’ observed during the mission was presented. As a result, the OD accuracy of ‘Best-of-4’ Position Fix Algorithm with 0 degree of mask angle was slightly better than that of ‘N-in-View’ Position Fix Algorithm. On the other hand, the GPS visibility under ‘N-in-View’ Algorithm is better than that of ‘Best-of-4’ Algorithm. The occurrence of temporal 3D Fix Loss is reduced when the ‘N-in-View’ Position Fix Algorithm was selected.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.2
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• pp.156-163
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• 2013

Collision probability is the most common method to measure the risk of space debris, it is widely used that two dimensional linear collision probability using the closest approach distance. This paper represents the characteristics of object that approach KOMPSAT 2, 3, 5 that have operated or will be operated by Korea. And more precise method than two dimensional linear collision probability, we analyzed the properties of three dimensional nonlinear collision probability using STK/Nonlinear Collision Probability Tool. Through this, efficiency of three dimensional nonlinear collision probability for KOMPSAT series satellites was investigated. The result represents that three dimensional nonlinear collision probability showed the precise outcome at a relative velocity of less than 350m/s. Also, KOMPSAT series satellites appeared to few low relative velocity approaches and showed low efficiency for the three dimensional nonlinear collision probability.