• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.674-682
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• 2014

Radio Frequency Test Set (RFTS) is essential to verify Telemetry, Command & Ranging (TC&R) RF subsystem of both Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO) satellite during Assembly Integration & Test (AI&T). The existing RFTS was specialized for each project and needed to be modified for each new satellite. The new design enables RFTS to be used in various projects. The hardware and software was designed considering this and therefore it could be directly used in other projects within a similar test period without modification or inconvenience. It will be also easily controlled, modified, and managed through the extension in modularization according to each function and the use of COTS (commercial on-the-self) and this will improve system reliability. A more reliable RF test measurement is also provided in this new RFTS by using an accurate reference clock signal.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.1-9
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• 2011

The Communication Ocean and Meteorological Satellite(COMS), the first geostationary observation satellite, was successfully launched on June 27th in 2010. The raw data of Meteorological Imager(MI) and Geostationary Ocean Color Imager(GOCI), the main payloads of COMS, is delivered to end-users through the on-ground processing. The COMS Image Data Acquisition and Control System(IDACS) developed by Korea Aerospace Research Institute(KARI) in domestic technologies performs radiometric and geometric corrections to raw data and disseminates pre-processed image data and additional data to end-users through the satellite. Currently the IDACS is in the nominal operations phase after successful in-orbit testing and operates in National Meteorological Satellite Center, Korea Ocean Satellite Center, and Satellite Operations Center, During the in-orbit test period, validations on functionalities and performance IDACS were divided into 1) image data acquisition and transmission, 2) preprocessing of MI and GOCI raw data, and 3) end-user dissemination. This paper presents that IDACS' operational validation results performed during the in-orbit test period after COMS' launch.

• Journal of Astronomy and Space Sciences
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• v.8 no.1
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• pp.99-113
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• 1991

We developed a software system called IODS(ISSA Orbit Determination System), which can predict the orbit of arbitary artificial satellite using the numerical method. For evaluating the orbit prediction accuracy of IODS, the orbital data predicted for the meteorological satellite NOAA-11 and the stationary satellite INTELSAT-V are intercompared with those tracked at the Central Bureau of Meterology and the Kum-San Satellite Communication Station. And the Perturbations affecting the orbit of these artificial satellites are quantitatively analyzed. The orbital variation and the eclipse phenomina due to the shadow are analyzed for a hypothetical geostationary satellite called KORSAT-1 which is assumed to be located in longitude $110^{circ}E$.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.251-260
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• 1998

We consider the motion of the subsystems as separate bodies as well as the entire satellite for the attitude and orbit control of a communication satellite by multi-body modeling technique. Thus, the system, can be applied to a general communication satellite as well as a specific communication satellite, i. e. Koreasat I,II. The simulation results can be viewed by two-dimensional graphics and three-dimensional animation. The graphical user interface(GUI) makes its usage much simpler. We have simulated a couple of scenarios for Koreasat I,II which are being operated as geostationary communication satellites to verify the system performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.62-71
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• 2015

Geostationary satellites use the thruster in order to control the location change and mount the suitable amount of liquid propellant depending on the operating lifetime. Therefore the lifetime of the geostationary satellite depends on the residual propellant amount and the precise residual propellant gauging is very important for the mitigation of economic losses arised from premature removal of satellite from its orbit, satellites replacement planning, slot management and so on. The propellant gauging methods of geostationary satellite are mostly used PVT method, thermal mass method and bookkeeping method. In this paper, we analysis the modeling of COMS(Communication, Ocean & Meteorological Satellite) bipropellant system for bookkeeping method and COMS GTO(Geostationary Transfer Orbit) injection propellant estimation using Monte-Carlo method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2763-2771
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• 1997

To determine the satellite orbital positions considering interference caused by inter-satellite systems is one of the most improtant issues in terms of optimal usage of satellite network resources. In this paper, considering ITU filing situation, we present the satellite orbital positions determination method to minimize iter-satellite system interference effect in the fixed satellite communication using an optimization method. Through the computer simulatio, it was shown that the proposed method is suitable to determine the satellite orbital positions.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1235-1243
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• 2021

Geostationary Ocean Color Imager 2 (GOCI-II) on Geo-KOMPSAT-2 (GK2B)satellite was developed as a mission successor of GOCI on COMS which had been operated for around 10 years since launch in 2010 to observe and monitor ocean color around Korean peninsula. GOCI-II on GK2B was successfully launched in February of 2020 to continue for detection, monitoring, quantification, and prediction of short/long term changes of coastal ocean environment for marine science research and application purpose. GOCI-II had already finished IAC and IOT including early in-orbit calibration and had been handed over to NOSC (National Ocean Satellite Center) in KHOA (Korea Hydrographic and Oceanographic Agency). Radiometric calibration was periodically conducted using on-board solar calibration system in GOCI-II. The final calibrated gain and offset were applied and validated during IOT. And three video parameter sets for one day and 12 video parameter sets for a year was selected and transferred to NOSC for normal operation. Star measurement-based INR (Image Navigation and Registration) navigation filtering and landmark measurement-based image geometric correction were applied to meet the all INR requirements. The GOCI2 INR software was validated through INR IOT. In this paper, status and results of IOT, radiometric calibration and INR of GOCI-II are analysed and described.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.5-10
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• 2005

The geostationary satellite propulsion system has thermistors which can measure liquid propellant temperature at tanks, pipes and etc. In the satellite propulsion system with several tanks, the propellant in the tanks is moved by temperature change and this temperature pattern is constant. In this paper, the temperature change pattern of KOREASAT 1 propulsion system is compared and the prediction study of pressurant inflow using temperature change of geostationary satellite propulsion system is described.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.145-154
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• 2007

Antenna pointing analysis for a geostationary satellite has been performed for using the NORAD Two-Line-Elements (TLE) converted from osculating Keplerian orbital elements. In order to check the possibility of the reception of the satellite signal, the antenna offset angles have been derived for the Communications, Ocean, and Meteorological Satellite (COMS) which carries out weekly East-West and North-South station-keeping maneuvers and twice a day thruster assisted momentum dumping. Throughout the analysis, it is shown that the use of converted NORAD TLE simplifies the antenna pointing related interfaces in satellite mission control system. For a highly eccentric transfer orbit cases, further analysis presents that the converted NORAD TLE from near apogee gives more favorable results.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.345-347
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• 2015

인공위성은 다양한 센서장치, 구동장치, 전자장치들로 구성되어 있으며, 위성을 제어하는 컴퓨터 장치는 이들 장치들과 다양한 종류의 통신 버스로 연결되어있다. 정의된 프로토콜에 따라 명령을 전송하고 장치들의 상태 정보를 수집하여 위성을 운영한다. 위성에서 많이 사용되는 대부분의 상용 센서나 구동장치들은 표준화된 버스 (ex, 1553B, CAN, UART, etc ...) 인터페이스를 지원한다. 그러나 위성의 임무나 설계에 맞게 특수하게 제작된 장치의 경우는 범용의 버스보다는 용도에 적합한 프로토콜이 설계되고 제작된다. 본 논문에서는 2018년 발사 예정인 정지궤도복합위성 컴퓨터 장치 (GMU) 내의 프로세스 모듈과 시스템의 이상상태를 감지하여 GMU의 운용 모드 및 형상의 변경을 담당하는 MRE 모듈사이의 통신을 담당하는 IMGL 설계를 소개하고 IMGL 운영을 담당하는 소프트웨어 설계 및 구현 내용을 기술한다.