• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1992.06a
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• pp.635-640
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• 1992

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.93-97
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• 2017

In satellites, even a small error in flight software could cause a failure of missions. Therefore, there are strict development and verification processes for a high reliability of flight software. However, satellites on orbits could meet unexpected situations including hardware malfunction. In this case, it is necessary for flight software to be updated to cope with the unexpected situations and to continue their missions. This paper reviews reprogramming capability of next generation LEO satellites.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.921-924
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• 2010

정지궤도 위성을 제외한 대부분의 저궤도 위성 및 심우주 관측용 위성은 임무를 수행하면서 하루동안에도 제한된 시간동안만 지상국과의 통신이 가능하다. 따라서 위성 운영에 고수준의 자율적 제어기능이 요구된다. OBCP(On-Board Control Procedures)는 별도로 개발된 언어로 작성한 작은 용량의 스크립트 프로그램을 통해 위성을 제어하는 기능을 제공한다. 이러한 방법을 통해 지상관제 시에 위성의 임무수행동안 수행되어야 하는 다양하고 복잡한 운영 시퀀스를 용이하게 준비하고 업로드할 수 있다. OBCP는 위성비행소프트웨어와는 분리된 별도의 서브시스템으로 수행되기 때문에 새로운 위성운영 프로시져의 생성을 위해 위성비행소프트웨어의 수정, 재검증, 코드업로드 등의 절차가 요구되지 않으며 지상에서 개발 및 검증시험을 완벽하게 수행할 수 있다. 본 논문에서는 기존의 저궤도 관측위성에서 사용되었던 위성의 자율적 제어 시퀀스 기능과 OBCP의 기능을 비교하여 설명하고, 실제 Herschel and Plank 위성에 활용된 예를 통해 OBCP의 개념 및 설계 방안에 대하여 소개한다.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.58-66
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• 2023

The latest global issues are the Space economy and low-orbit Space communication. 3GPP announced Release 17 standardization in June 2022, and in this regard, the United States prepared a strategy to enhance the competitiveness of the low-orbit 5G-NTN Space industry, and create an ecosystem at the national level in March 2023. Global smartphone semiconductor manufacturers have announced the development and verification results of standard-based chip technology, and satellite communication operators are launching low-orbit 5G-NTN Space communication services and rate products through convergence between terrestrial communication networks. This study diagnoses the current status of Korea's low-orbit 5G-NTN space communication ecosystem. We present our ecosystem creation strategy in terms of fair competition in the market, the service legal system, and the national R&D governance system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.747-752
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• 2007

Domestic satellite development programme is generally classified into two categories: COMS as GEO satellite and KOMPSAT as LEO one. Each satellite has the on-board propulsion system fulfilling its own mission requirements. The COMS propulsion system provides the thrust and torque required for the insertion into GEO, attitude and orbit control/adjustment of spacecraft. It is the well-known Chemical Propulsion System(CPS) using bipropellants. On the other hand, the monopropellant propulsion system is employed in KOMPSAT, and its main role is on-station attitude control excluding the orbit transfer function. In this study, these two representative propulsion systems are compared and analysed as well, in terms of essential differences and important characteristics.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.111-116
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• 2013

Because LEO (Low Earth Orbit) satellite has very limited contact time between satellite and ground station, all telemetry data generated on satellite are stored in a mass memory and transmitted to the ground during the contact time. There are two downlink modes, real-time mode and playback mode. Only real-time data frames are transmitted to the ground in real-time mode, real-time and playback data frames stored into mass memory are transmitted to the ground in playback mode. In accordance with the data transmission rate, there are two downlink rates, low downlink rate and high downlink rate. This paper briefly introduces downlink interfaces and flight software of a LEO satellite developed in KARI. And it presents the telemetry storage method, real-time and playback downlink management method, and downlink channel and rate control method.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.65-71
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• 2016

Currently developing the OBC of the next-generation LEO satellite by Korea Aerospace Research Institute adopts the LEON2-FT/AT697F processor to achieve high performance. And various communication devices such as SpaceWire, MIL-STD-1553B, DMAUART and CAN Master are integrated to the separated standard communication FPGAs within the OBC, where they can be controlled by the processor and flight software (FSW) through PCI interface. The Actel 1553BRM IP core is used for the 1553B in the next-generation LEO OBC and the B1553BRM wrapper from Aeroflex Gaisler is used for connecting it to the AMBA bus in FPGA. This paper presents the design and development of PCI-based 1553B communication software, and describes the handling mechanism of 1553B operation in FSW task level. Also it shows the test results on real-hardware and simulator.

• The Magazine of the IEIE
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• v.19 no.10
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• pp.95-102
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• 1992

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1998.10a
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• pp.1159-1162
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• 1998

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1998.10a
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• pp.1163-1166
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• 1998