• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.511-518
• /
• 2008

The Engineering Test Satellite VIII(ETS-VIII) of Japan Aerospace Exploration Agency(JAXA) uses a 20mN class xenon ion engine subsystem(IES) for North-South Station Keeping(NSSK). The IES was modified for a larger satellite with longer lifetime based on the former IES. ETS-VIII, a three-ton class geosynchronous satellite with 10 years bus lifetime, was launched 18 Dec. 2006 JST; it reached the planned orbit and all bus systems were checked out. The IES showed good results and is now under normal operation. The total accumulated operation time of the IES in orbit was about 2300 hours till $19^{th}$ Dec. 2007.

• Journal of computational fluids engineering
• /
• v.13 no.2
• /
• pp.48-54
• /
• 2008

COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean and meteorological observations. It will be launched by ARIANE 5. Ka-band components are installed on South panel, where single solar array wing is mounted. Radiators, embedded heat pipes, external heat pipe, insulation blankets and heaters are utilized for the thermal control of the satellite. The Ka-band payload section is divided several areas based on unit operating temperature in order to optimize radiator area and maximize heat rejection capability. Other equipment for sensors and bus are installed on North panel. The ocean and meteorological sensors are installed on optical benches on the top floor to decouple thermally from the satellite. During the transfer orbit operation, satellite will be under severe thermal environments due to low dissipation of components, satellite attitudes and LAE(Liquid Apogee Engine) firing. This paper presents temperature and heater power prediction and validation of thermal control design during transfer orbit operation.

• Proceedings of the KSRS Conference
• /
• 2006.03a
• /
• pp.398-403
• /
• 2006

2008년 발사를 목표로 개발되고 있는 통신해양기상위성(COMS : Communication, Ocean and Meteorological Satellite)의 기상 탑재체를 이용한 기상 관측 임무는 기상청 기상위성센터(가칭)의 고유 임무로서, 이는 기상탑재체에서 관측한 자료를 수신 처리하여 고품질의 영상과 분석 자료를 생산하여 기상 예보 업무에 활용하고, 위성을 통하여 국내외 사용자들에게 분배하는 것 등을 포함한다. 위성을 통한 기상 자료 서비스는 국내에서는 최초로 시도되는 것으로, 국제기상위성운영 기관들의 모임인 기상위성조정그룹회의(CGMS Coordination Group for Meteorological Satellites)에서 권고하는 High Rate Information Transmission/Low Rate Information Transmission(HRIT/LRIT)라는 특정 자료 형태를 사용하여 분배하게 된다. 따라서 본 논문에서는 CGMS에서 권고하는 CCSDS (Consultative Committee for Space Data Systems) 전송 규격과 일본의 MTSAT-1R(Multi-functional Transport Satellite) 위성 사용자 서비스 자료 형태를 참고하여 통신해양기상위성의 효과적인 기상자료 분배를 위한 HRIT/LRIT 데이터 전송률을 분석하여 보았다.

• Proceedings of the KSRS Conference
• /
• v.1
• /
• pp.196-199
• /
• 2006

Various communication mechanisms have been developed to acquire a meaningful data from sensors. The key requirement during the sensor data acquisition is determinism and reduction of time dependency. It is a fundermental level of satellite data management for controlling satellite operation software data acquisition from sensors or subsystem. Satellite operation software has various software modules to be operated in addition to data acquisition. Therefore, unnecessary time delay shall be minimized to perform the data acquisition. As the result, interrupt method might be prefered than polling method because the former can decrease the restriction of design during implementation of data acquisition logic. The possible problems while using interrupt method like as interrupt latency caused by delaying of interrupt processing time are analyzed. In this paper, communication mechanism which can be used to interface with satellite computer and subsidary subsystem by using interrupt is presented. As well, time dependency between software scheduling and data acquisition is analyzed.

• 제어로봇시스템학회:학술대회논문집
• /
• 1994.10a
• /
• pp.38-43
• /
• 1994

To provide more instructive and a safer ground control operation environments for satellite operators, and subsequently to implement a better look-and-feel user interface and a structural mechanism to enhance the efficiency of control and monitoring facilities, we have developed a prototype(laboratory model) ground control softwares targeting for the first generation KOREASAT scheduled to be launched in 1995. As far as the functionality is concerned, the developed system is covering almost all the mission phase operational functions except for some functions like antenna tracking control that are necessary for real operation environments. Most of the functions of the system is realized in softwares but some hardwares needed for TM/TC RF communications are also included in it. The system is now being integrated and under the system test. The performance and functionality is to be evaluated by the end of this year by using the satellite software simulator. Next year, this system could be configured to be used as a workbench for a online/off-line analysis of the operating KOREASAT satellites.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.2
• /
• pp.147-158
• /
• 2020

In this paper, we will review the thruster based reaction wheel momentum dumping method for low Earth orbit satellite. Thruster based momentum dumping is widely used in GEO satellites by performing momentum dumping and attitude control using thrusters at the specific time. LEO satellite should perform momentum dumping at any time, thus it is not appropriate to use GEO satellite's momentum dumping method. In this research, we will review the method for LEO satellite, which perform momentum dumping always and use reaction wheels for attitude control during dumping. To reduce thruster's valve on and off counts, we propose to use the maximum pulse width for thruster operation. To prevent attitude error increase by thrusters, we adjust the thruster operation interval. Through simulation, we verify the proposed method's effects.

• Korean Journal of Remote Sensing
• /
• v.36 no.6_2
• /
• pp.1537-1549
• /
• 2020

The ground sample distance of KOMPSAT-3 is 0.7 m for panchromatic band, 2.8 m for multi-spectral band, and the swath width of KOMPSAT-3 is 16 km. Therefore, an image of an area wider than the swath width (16 km) cannot be acquired with a single scanning. Thus, after scanning multiple areas in units of swath width, the acquired images should be made into one image. At this time, the necessary algorithm is called image mosaicking or image stitching, and is used for cartography. Mosaic algorithm generally consists of the following 4 steps: (1) Feature extraction and matching, (2) Radiometric balancing, (3) Seamline estimation, and (4) Image blending. In this paper, we have studied an effective seamline estimation method for satellite images. As a result, we can estimate the seamline more accurately than the existing method, and the heterogeneity of the mosaiced images was minimized.

• Journal of Korea Society of Industrial Information Systems
• /
• v.15 no.2
• /
• pp.17-22
• /
• 2010

Establishment of systematic platform is needed for technological progress of receiving of satellite image data with high quality and processing system for product generation and operation related with direct receiving system for satellite from abroad. Besides, it's necessary to develop the integrated data processing system to prohibit similar functions on developing (or being developed) for KOMPSAT-3, KOMPSAT-5 and to operate system efficiently. Therefore, conceptual design of the integrated data processing system is performed considering commercialization of KOMPSAT(Korea Multi-Purpose Satellite) series based on KOMPSAT-2 IRPE on operation in this paper.

• Aerospace Engineering and Technology
• /
• v.9 no.2
• /
• pp.176-184
• /
• 2010

The power simulator for a LEO satellite is a useful tool to analyze mission validity and energy balance for various mission scenarios by estimating power generation, power consumption, depth of discharge, bus voltage, charging/discharging current, etc. In this paper, it is described the calculation algorithm of the solar array (SA) power, the satellite load power and the battery modeling method to develop a satellite power simulation. To simulate the SA power generation, three different operation modes (DET, MPPT, CV) of SAR (Solar Array Regulator) are considered with a SA model. The satellite load power is estimated using the satellite unit power database, the unit on/off configuration at some satellite operation modes. The bus voltage and battery charging/discharging current at the specific DoD (Depth of Discharge) are calculated based on the battery characteristics. By this satellite power simulator, it can be conveniently analyzed the energy balance and the validity of a planned mission of a LEO satellite.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.11
• /
• pp.41-47
• /
• 2005

Even more than 240 commercial geostationary communication satellites currently on orbit at the higher location than the GPS orbit altitude perform their own missions only by the support of the ground segment because of weak visibility from GPS. In addition, the orbit determination accuracy is very low without using two or more dedicated ground tracking antennas in intercontinental ground segment, since the satellite hardly moves with respect to the ground station. In this paper, we propose the GSPS(Geostationary Satellite Positioning System) in circular orbits of two sidereal days period higher than the geosynchronous orbit for orbit determination and autonomous satellite operation. The GSPS is conceived as a ranging system in that unknown positions of a geostationary satellite can be acquired from the known positions of the GSPS satellites. Each GSPS satellite transmits navigation data, clock data, correction data, and geostationary satellite command to control a geostationary satellite.