• 우주기술과 응용
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• 제3권3호
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• pp.280-300
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• 2023

본 논문은 한국항공우주연구원에서 운영 중인 우주물체 충돌위험 관리시스템의 개발 및 운영 현황을 포함하고 있다. 현재 저궤도위성 6기, 정지궤도위성 3기에 대해 24시간 충돌위험을 모니터링하고 있으며, 필요 시 충돌회피기동을 통해 충돌위험을 완화하여 안전하고 안정적으로 운영하고 있다. 2007년 중국의 자국위성 요격실험 이후 본격적으로 우주물체와 운영위성 간 충돌위험을 모니터링하고 있으며, 신속하고 효율적으로 상황에 대처하기 위해 다양한 충돌위험 관리시스템을 개발해왔다. 본 논문에서는 2007년 이후 현재까지 개발된 우주물체 충돌위험 관리시스템에 대한 소개, 현재 지구주변의 인공우주물체 현황, 현재 운영 중인 시스템에 대해 기술하였으며, 나아가 앞으로의 전망과 향후 계획에 대해 소개하였다.

• Journal of Astronomy and Space Sciences
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• 제34권4호
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• pp.271-280
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• 2017

This study presents the application of satellite laser ranging (SLR) to orbit determination (OD) of high-Earth-orbit (HEO) satellites. Two HEO satellites are considered: the Quasi-Zenith Satellite-1 (QZS-1), a Japanese elliptical-inclinedgeosynchronous-orbit (EIGSO) satellite, and the Compass-G1, a Chinese geostationary-orbit (GEO) satellite. One week of normal point (NP) data were collected for each satellite to perform the OD based on the batch least-square process. Five SLR tracking stations successfully obtained 374 NPs for QZS-1 in eight days, whereas only two ground tracking stations could track Compass-G1, yielding 68 NPs in ten days. Two types of station bias estimation and a station data weighting strategy were utilized for the OD of QZS-1. The post-fit root-mean-square (RMS) residuals of the two week-long arcs were 11.98 cm and 10.77 cm when estimating the biases once in an arc (MBIAS). These residuals were decreased significantly to 2.40 cm and 3.60 cm by estimating the biases every pass (PBIAS). Then, the resultant OD precision was evaluated by the orbit overlap method, yielding three-dimensional errors of 55.013 m with MBIAS and 1.962 m with PBIAS for the overlap period of six days. For the OD of Compass-G1, no station weighting strategy was applied, and only MBIAS was utilized due to the lack of NPs. The post-fit RMS residuals of OD were 8.81 cm and 12.00 cm with 49 NPs and 47 NPs, respectively, and the corresponding threedimensional orbit overlap error for four days was 160.564 m. These results indicate that the amount of SLR tracking data is critical for obtaining precise OD of HEO satellites using SLR because additional parameters, such as station bias, are available for estimation with sufficient tracking data. Furthermore, the stand-alone SLR-based orbit solution is consistently attainable for HEO satellites if a target satellite is continuously trackable for a specific period.

• 대한원격탐사학회지
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• 제38권6_4호
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• pp.1871-1877
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• 2022

과거 위성개발에는 막대한 예산과 시간이 소요됨에 따라 일부 선진국만 위성을 보유하였으나, 최근 초소형위성과 같은 저예산 위성이 등장함에 따라 전 세계 많은 국가들이 위성 개발에 참여하고 있다. 저궤도 및 정지궤도 위성은 환경 및 기상 감시, 정밀변화탐지, 재난 등 다양한 분야에서 활용되고 있으며, 최근에는 딥러닝 기반의 관심 객체탐지 등을 통한 모니터링에도 활발히 이용되고 있다. 우리나라는 지금까지 우주개발계획에 따라 국가 수요의 위성을 개발하여 왔으며, 이를 통해 획득한 위성영상은 공공 및 민간에서 다양한 목적으로 활용되고 있다. 국내에서 위성영상에 대한 관심은 지속적으로 증가하고 있으며, 각종 아이디어 발굴 및 기술개발 촉진을 위한 다양한 경진대회도 개최되고 있다. 본 특별호에서는 최근 개최된 2022 위성정보활용 경진대회에 참여한 주제와 다목적실용위성 영상자료 처리 및 활용 연구에 대해서 소개하고자 한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.296-298
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• 1999

Five institutions, which are very active in data utilization of environmental satellites NOAA and GMS, are connected via high speed networks to construct the databases based on the observations of A AVHRR (Advanced very High Resolution Radiometer) of NOAA satellite and VISSR (Visible and Infrared Scanning Radiometer) of GMS (Geostationary Meteorological Satellite) and to create scientific data sets for land, ocean and ,atmosphere. And vegetation index, sea surface temperature, cloud distribution maps and so on are generated by high speed and huge volume data Processing for studies on long term variations of land, ocean and atmosphere in Asia. In this paper the concept of this project and the activities at the Science University of Tokyo are briefly introduced

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.997-1000
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• 2006

We estimate the net heat flux in the tropical and subtropical Atlantic Ocean using satellite data. These fluxes are related to changes in sea surface temperature (SST). This variable influences atmospheric circulations and is indicative of surface and subsurface oceanic circulations. We employ data from the geostationary METEOSAT-7 and 8 satellites and from the Special Sensor Microwave/Imager (SSM/I) for the shortwave and long-wave radiative fluxes, and for estimates of SST. For turbulent flux calculations, we use the bulk aerodynamic method with satellite estimates for wind speed and atmospheric humidity and temperature.

• Journal of Positioning, Navigation, and Timing
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• 제8권4호
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• pp.215-223
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• 2019

This paper analyzes navigation performances of the Korean Positioning System (KPS) constellation with respect to the orbit parameters which fulfills the specification requirements. Specifically, the satellite configuration and navigation requirements of KPS are explained, and the daily mean horizontal dilution of precision (HDOP) and satellite visibility on KPS coverage are analyzed to confirm the adequate orbit parameters. However, due to orbital slot saturation, geostationary-orbit (GEO) satellites may not be allocated in the original orbit as specified in the KPS requirements. Therefore, in a spanned window of 4 degrees from the reference longitude the navigation performance of each GEO satellite orbit is investigated.

• 항공우주정책ㆍ법학회지
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• 제9권
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• pp.421-433
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• 1997

The orbit and frequency spectrum allocation for the communication and broadcasting satellite services are coordinated between the concerned parties according to the Radio Regulations of International Telecommunication Union (ITU). Currently, the geostationary orbit is filled with too many satellites for the commercial or military uses. In addition, a number of near earth satellite programs are being introduced. As each country claims for the space orbit and spectrum, the limited space resources are being exhausted. In this paper, the current situations in the worldwide satellite orbit demand are discussed, and some ideas on the peaceful, efficient and equitable use of space resources are proposed.

• Journal of Positioning, Navigation, and Timing
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• 제6권1호
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• pp.35-41
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• 2017

Precise Point Positioning (PPP) method is based on dual-frequency data of Global Navigation Satellite Systems (GNSS). The recent multi-constellations GNSS (multi-GNSS) enable us to bring great opportunities for enhanced precise positioning, navigation, and timing. In the paper, the multi-GNSS PPP with a combination of four systems (GPS, GLONASS, Galileo, and BeiDou) is analyzed to evaluate the improvement on positioning accuracy and convergence time. GNSS observations obtained from DAEJ reference station in South Korea are processed with both the multi-GNSS PPP and the GPS-only PPP. The performance of multi-GNSS PPP is not dramatically improved when compared to that of GPS only PPP. Its performance could be affected by the orbit errors of BeiDou geostationary satellites. However, multi-GNSS PPP can significantly improve the convergence speed of GPS-only PPP in terms of position accuracy.

• Journal of Positioning, Navigation, and Timing
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• 제3권4호
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• pp.149-154
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• 2014

The BeiDou is a satellite-based positioning and navigation system, which is under construction by the China Satellite Navigation Office. Until the June of 2014, the constellation of BeiDou navigation satellite system consists of 14 satellites including five geostationary earth orbit (GEO), five inclined geosynchronous earth orbit (IGSO) and four medium earth orbit (MEO). In this paper, we present the positioning results using BeiDou B1 code measurements obtained from three GNSS reference stations (BHAO, SKMA, MKPO). Combined Beidou/GPS positioning results are also compared to BeiDou and GPS only. BeiDou-only positioning errors for the east-west and north-south direction had less than 2 meter with root mean square (RMS) value. However, the positioning error for the up-down direction had larger than 10 meter at a 95% confidence level. Our results also suggest that the position precision is improved by combined BeiDou/GPS compared to BeiDou-only.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.309-310
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• 2007

Spacecrafts such as most of commercial satellites that are operating in the geostationary orbit can be subjected to intense irradiation by charged particles. The surface made of dielectric materials can therefore become probable sites for damaging electrostatic discharges. Thanks to a specially equipped chamber, the spatial environment can be reproduced experimentally in the laboratory. In this paper, the behavior of high energy electrons injected in polymers such as PolyMethylMetaAcrylate (PMMA) and Kapton is studied. Results obtained by surface potential technique, pulse-electro acoustic device and a cell based on the split Faraday cup system are analyzed and discussed.