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

• Aerospace Engineering and Technology
• /
• v.8 no.2
• /
• pp.1-7
• /
• 2009

The Geostationary Ocean Color Imager (GOCI) is under development to provide a monitoring of ocean-color around the Korean Peninsula from geostationary platforms. It is planned to be loaded on Communication, Ocean, and Meteorological Satellite (COMS) of Korea. In this study, the radiometric model of GOCI, which is constructed based on the functional model of sub-system, is introduced. Non-linearity for each channel is analyzed in terms of linear gain and nonlinear gain by using the radiometric model. The non-linearity characteristic is validated by using test data which have been achieved during ground test at payload level. The non-linearity $G^3$/b shows identical characteristic for all channels.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.5
• /
• pp.439-445
• /
• 2012

The COMS(Communication, Ocean, and Meteorological Satellite) is subjected to shock loads when the stage or fairing of a launch vehicle is separated and the satellite is separated from the launch vehicle during the launch vehicle flight. And, after the satellite is separated from the launcher, the COMS is subjected to shock loads when the solar array is deployed, Ka-Band communication antenna is deployed, and meteorological imager radiator cover is released. In order to validate the satellite safety against these shock loads on ground, shock tests were performed. In this paper, the shock tests performed in the course of the COMS development are described, and the method to assess the test result is presented with an example of Geostationary Ocean Color Imager(GOCI). In Ariane-5 launch vehicle, the clampband release shock for satellite separation is lower than the fairing or stage separation. In this paper, the extrapolation method to take into account the maximum shock load from the launch vehicle by using the satellite separation shock test result is also introduced.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.564-566
• /
• 2005

The relation between HPA (High Power Amplifier) and COMS (Communication Ocean Meteorological Satellite) multi-carrier is analyzed in this paper. MODAC (Meteorological and Ocean Data Application Center) has a primary mission to transmit processed data, HRIT (High Rate Information Transmission) and LRIT (Low Rate Information Transmission), which is normalized and calibrated by pre-processing. It is also replaced with the SOC (Satellite Operation Center) in emergency case and can transmit the command and ranging tones for operation of COMS. From the result of simulation with modelled HPA, it is found that the multi-carrier in one HPA can give rise to an inter-modulation which makes harmonic and spurious elements increase in-band. Under the environment of these increased parasitic elements, the degradation of multi-carrier's quality is estimated from the ratio of the amount of noise to total output power of HPA.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.04a
• /
• pp.142-147
• /
• 2009

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 tested under vacuum condition and very low temperature in order to verify thermal design of COMS. The test will be performed by using KARI large thermal vacuum chamber, which was developed by KARI, and the COMS will be the first flight satellite tested in this chamber. The purposes of thermal balance test are to correlate analytical model used for design evaluation and predicting temperatures, and to verify and adjust thermal control concept. KARI has plan to use heating plates to simulate space hot condition especially for radiator panels such as north and south panels. They will be controlled from 90K to 273K by circulating GN2 and LN2 alternatively according to the test phases, while the shroud of the vacuum chamber will be under constant temperature, 90K, during all thermal balance test. This paper presents thermal modelling including test chamber, heating plates and the satellite without solar array wing and Ka-band reflectors and discusses temperature prediction during thermal balance test.

• Proceedings of the KSRS Conference
• /
• 2006.03a
• /
• pp.381-385
• /
• 2006

2008년 발사를 목표로 개발되고 있는 통신해양기상위성(COMS: Communication, Ocean and Meteorological Satellite)는 기상 관측과 해양 관측 임무 및 통신 임무까지 수행하는 정지궤도 위성이다. 통신해양기상위성은 크게 탑재체와 지상국으로 나눌 수 있고 지상국은 다시 통신 임무를 위한 CTES(Communication Test Earth Station), 해양/기상 임무를 위한 IDACS(Image Acquisition and Control System), 그리고 위성 관제와 운영을 위한 SGCS(Satellite Ground Control System)로 구분된다. 이 중 IDACS의 서브시스템 중 하나인 LHGS(LRIT/HRIT Generation Subsystem)는 LRIT/HRIT(Low Rate Information Transmission/High Rate Information Transmission)를 생성하고 배포하는 기능을 가지고 있다. 관측 종료 후 LRIT/HRIT 전송 완료까지 15분 이내로 이루어져야 한다는 기상청의 요구사항을 만족하기 위해서 JPEG 압축 시간도 중요한 요소로 고려되어야 한다. 그래서 본 논문에서는 MTSAT에서 받은 LRIT/HRIT의 자료 처리를 바탕으로 lossless JPEG와 lossy JPEG의 압축 시간을 측정하여 압축률을 비교하여 성능 분석을 해보기로 한다. 이렇게 도출해낸 수치자료는 COMS LHGS 설계에 활용할 수 있다.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.336-339
• /
• 2004

Communication, Ocean and Meteorological Satellite (COMS) has been developed by Korean Aerospace Research Institute (KARI) since 2003. Ocean Color Imager (OCI) is the one of COMS payloads, which will monitor the marine environment around Korean peninsula routinely with the intermediate resolution. But considering COMS is to be located in the geostationary orbit, required geographical coverage is not positioned in the nadir direction of COMS but in specific location with horizontal and vertical offsets from the nadir. In this study, coverage by OCI Field Of View (FOV) is analyzed. First of all, OCI is modeled as the sensor which is a $2,500{\times}2,500$ sized 2-D CCD and the pixel resolution is about 500m. And then, OCI is simulated to be controlled to target the required coverage accurately. As a result of it, coverage by OCI FOV is determined. Finally, all coverages by OCI FOV are mapped.

• Journal of computational fluids engineering
• /
• v.10 no.3 s.30
• /
• pp.63-69
• /
• 2005

The COMS, the first meteorological geostationary satellite in Korea, is under development by KARI. The radiator size and the heater power for the thermal control of COMS are calculated using an analytic method. The total radiator area of $4.85\;m^2$ and the total heater power of 794.77 W are determined at a conceptual design of COMS. The commercial software, SINDA and TRASYS, are utilized in order to compare and verify the analytic results. The results of on-orbit numerical simulation of cold and hot cases show that the radiator size and heater power obtained from the analytic method are appropriate to maintain COMS equipments within required temperature ranges.

• Aerospace Engineering and Technology
• /
• v.2 no.1
• /
• pp.182-189
• /
• 2003

Communication Ocean Meteorological Satellite(COMS) for the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service is planned to be launched onto Geostationary Earth orbit (GEO) in 2008 according to the korea national space program, For the development of the meteorological payload of COMS, imager, the characteristics of Modulation Transfer Function (MTF) for GEO meteorological imager is investigated and the theoretical MTF limit is analyzed for each spectral channel of the imager in the both cases of a currently operating GEO instrument technology and an advanced GEO instrument technology under development. This study shows that MTF value can be considerably low in the infrared channels with longer wavelength than 10㎛ due to diffraction effect so that the MTF performance of long wavelength infrared channels should be paid attention to for the development of the imager.

• Proceedings of the KSRS Conference
• /
• v.1
• /
• pp.290-293
• /
• 2006

COMS (Communication, Ocean and Meteorological Satellite) shall be operated with two remote sensing payloads, MI (Meteorological Imager) and GOCI (Geostationary Ocean Color Imager). Since both payloads have rotating mechanisms, the dynamic coupling between two payloads is very important considering the pointing stability during GOCI operation. In addition, COMS adopts a single solar wing to improve the image quality, which leads to the unbalanced solar pressure torque in COMS. As a result, the off-loading of the wheel momentum needs to be performed regularly (2 times per day). Since the frequent off-loading could affect MI/GOCI imaging performance, another suboptimal off-loading time needs to be considered to meet the AOCS design requirements of COMS while having margin enough in the number of thruster actuations. In this paper, preliminary analysis results on the pointing stability and the wheel off-loading time selection with respect to MI/GOCI operations are presented.