• Electronics and Telecommunications Trends
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• v.37 no.3
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• pp.41-51
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• 2022

This article presents an overview of the key technologies in the communications payload of broadband LEO satellite communications systems. In recent years, new developments have been realized for LEO satellite communications. SpaceX's Starlink, a technology leader in this field, offers premium services with satellites carrying in-house developed communications payloads. OneWeb, Amazon, Telesat, and Boeing are also developing LEO satellite communications payloads. The communications payload consists of user link antennas, inter-satellite link communications equipment, feeder link antennas, and a digital processor. Highly sophisticated technologies of compact active phased array antennas for generating multiple hopping beams and light laser communication equipment for ultra-high-speed inter-satellite communication will be applied to next- generation payloads.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.756-759
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• 2012

This paper presents the multibeam service coverage of GEO(Geostationary Orbit) satellite and the practical antenna scheme scenarios to provide the universal communication services on the Korean peninsula. The proposed antenna systems consist of the simplest scheme and feed network so that they can be mounted on satellites. The feed networks are effectively organized according to the frequency and polarization plan. Despite simple structure, all scenarios meet the electrical performance by the optimization of feed allocation and feed excitation.

• Proceedings of the KSRS Conference
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• v.1
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• pp.372-375
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• 2006

The MSC is a high resolution multi-spectral camera system which is mounted on the KOMPSAT-II satellite. The electro-optic camera system has a refocusing mechanism which can be used in-orbit by ground commands. By adjusting locations of some elements in optics, the system can be focused precisely. The focus mechanism in MSC is implemented with stepper motor and potentiometer. By reading the value of the potentiometer, rough position of the motor can be understood. The exact location of the motor can not be acquired because the information from the potentiometer can not be so accurate. However, before and after certain events of the satellite, like a satellite launch, the direction of the movement or order of the magnitude of the movement can be understood. In this paper, the trend analysis of the focus motor position during the ground test phase is introduced. This result can be used as basic information for the focus calibration after launch. By studying the long term trend, deviation from the best focal point can be understood. The positions of the focus motors after launch are also compared.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.273-284
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• 2011

A method of stellar source selection for validating the quality of image is investigated for a low Earth orbit optical remote sensing satellite. Image performance of the optical payload needs to be validated after its launch into orbit. The stellar sources are ideal source points that can be used to validate the quality of optical images. For the image validation, stellar sources should be the brightest as possible in the charge-coupled device dynamic range. The time delayed and integration technique, which is used to observe the ground, is also performed to observe the selected stars. The relations between the incident radiance at aperture and V magnitude of a star are established using Gunn & Stryker's star catalogue of spectrum. Applying this result, an appropriate image performance index is determined, and suitable stars and areas of the sky scene are selected for the optical payload on a remote sensing satellite to observe. The result of this research can be utilized to validate the quality of optical payload of a satellite in orbit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.466-473
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• 2011

The purpose of satellite thermal control design is to maintain all the elements of a spacecraft system within their temperature limits for all mission phases. The thermal analysis model for Low Earth Orbit satellite payload level simulation is established by considering thermal vacuum test environment condition, thermal vacuum chamber configuration, and satellite's payload inner thermal environment. The established thermal analysis model is used to determine thermal vacuum test conditions and test case requirements.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.48-53
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• 2010

COMS (Communication, Ocean and Meteorological Satellite), which will be launched in June 23rd, 2010 and located on geostationary orbit at the latitude of $128.2^{\circ}E$, is a multi-function satellite for communications, ocean observation, and meteorology. In order to operate Ka-band communication payload effectively, which is one of the three payloads for COMS, the Transponder Monitoring and Control (TMC) system are necessary in ground systems. In this paper, the concepts and design of the TMC system for COMS Ka-band payload are described.

• Korean Journal of Remote Sensing
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• v.32 no.3
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• pp.287-305
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• 2016

Over the past half century, satellites have continuously expanded their roles in remote sensing applications. As the number of satellites to be launched are expected to continuously increase in coming years, the research on satellite payloads will be in high demands. Earth Observation (EO) satellites are nowadays widely utilized for various purposes. Especially, Agriculture and forestry applications are considered as their major application areas. Since about 85% of domestic land cover is classified as forest or cropland areas, it would be reasonable to suggest that the demand for these satellites should be of high priority. In this paper, a comprehensive analysis is performed on the technical specifications of satellite payloads that may be applicable to agricultural applications. We attempted to build a solid database on payload specifications by collecting relevant information available from various related institutes and academic research works. A number of experts involved in national agricultural research and satellite development programs have been invited to investigate required payload design. Based on the current technology development status and future plan, multiple options for future satellite payload designs have been suggested bearing in mind that the results may be applicable to the future agriculture and forestry satellite payload design. The proposed payload specifications are analyzed in depth through satellite operation simulations under the mission of observing the national agriculture areas. The proposed design scheme and simulation results may be used as technical references to satellite payload design for future space missions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1240-1247
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• 2010

This paper describes the study on the electrical design of a multi-beam large antenna for a satellite payload. This satellite antenna provides the universal communication and broadcasting services to personal portable terminals over the Korean Peninsula. The structure of the hybrid antenna fed by a feed array is proper to provide multi-beams. The amplitude and phase of each feed element should be optimized for a required beam and they can be obtained by GO (Geometrical Optics) and PO(Physical Optics) method. The number of feed elements are also optimized to meet the specification of EIRP(Effective Isotropically Radiated Power). The optimally designed antenna with the limited reflector size and minimum number of feed elements is shown in this paper.

• 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.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.88-96
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• 2023

KOMPSAT (Korean Multi-Purpose Satellite) is a Low-Earth-Orbit (LEO) satellite under development in Korea. Its performance has been steadily improving. At this time, power demand of the payload increased according to performance improvement of the payload. Accordingly, design of the satellite, such as design of the internal power supply device and the configuration of the solar array, was changed. Thus, many considerations are required according to an increase in power when designing power EGSE (Electric Ground Support Equipment) for supplying power to satellites and conduct satellite integration tests. This paper deals with matters to be considered when designing power EGSE according to changes in satellite power requirements according to payloads and increase in power requirements.