• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.170-178
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• 2009

In order to develope a common ground system, a general procedure language that can be used in both EGSE and MCS is primarily needed. As the first step in developing a common test and integration procedure language, KARI's ATS for AIT and MCE for GS were compared to some of the most representative languages such as PLUTO regarded European standard, STOL and ELISA and PIL. Based on the analysis, design features of developing a common test and integration procedure language were presented.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.129-139
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• 2012

This paper will describe the structure and characteristics of operator training system which was developed to maintain the quality of operational ability for COMS (Communication, Ocean and Meteorological Satellite) operators during a long-term nominal operations of missions and a contingency operations against an occurrence of anomaly. In particular it will present benefits and expected effects of the training system with a focus on three parts which are functions especially for trainer-friendly failure injection, an automatic sequencer of training scenario based on the predefined plan and additional functions of the existing COMS simulator. Furthermore, it will present a practical example of training on the training system to understand the overall mechanism of training process.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.252-256
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• 1998

Accurate mapping of satellite images is one of the most important Parts in many remote sensing applications. Since the position and the attitude of a satellite during image acquisition cannot be determined accurately enough, it is normal to have several hundred meters' ground-mapping errors in the systematically corrected images. The users which require a pixel-level or a sub-pixel level mapping accuracy for high-resolution satellite images must use a number of Ground Control Points (GCPs). In this paper, the performance of two geometric correction algorithms is tested and compared. One is the polynomial warping algorithm which is simple and popular enough to be implemented in most of the commercial satellite image processing software. The other is full camera modelling algorithm using Physical orbit-sensor-Earth geometry which is used in satellite image data receiving, pre-processing and distribution stations. Several criteria were considered for the performance analysis : ultimate correction accuracy, GCP representatibility, number of GCPs required, convergence speed, sensitiveness to inaccurate GCPs, usefulness of the correction results. This paper focuses on the usefulness of the precision correction algorithm for regular image pre-processing operations. This means that not only final correction accuracy but also the number of GCPs and their spatial distribution required for an image correction are important factors. Both correction algorithms were implemented and will be used for the precision correction of KITSAT-3 images.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.2
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• pp.61-68
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• 2003

The space systems are being operated in a uncertain space environment and are desired to have autonomous capability for long periods of time without frequent telecommunications with the ground station. At the same time, requirements for new set of satellite system set of projects/systems calling for "autonomous" operations for long unattended periods of time are emerging. Since, by the nature of space systems, it is desired to perform its mission flawlessly and also it is of extreme importance to have fault-tolerant sensors and actuators for the purpose of validating science measurement data for the mission success. This studies focused on the identification/demonstration of critical technology innovations that will be applied to the Validation Control System.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.238-243
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• 1999

Minimum-fuel and -time orbit transfer are two major goals of the satellite trajectory optimization. In this paper, we consider satellites in two coplanar elliptic orbits when the apsidal lines coincide, and analytically find the conditions for the two-impulse minimum-time transfer orbit using Lambert's theorem. The transfer time is a decreasing function of a variable related to the transfer orbit's semimajor axis in the minimum-time case. In the minimum-time case, there is no unique minimum-time solution, but there is a limiting solution. However, there exists a unique solution in the case of minimum-fuel transfer, fur which we find analytically the necessary and sufficient conditions. As a special case, we consider when the transfer angle is one hundred and eighty degrees. In this case, we show that we obtain the classical fuel-optimal Hohmann transfer orbit. We also derive the Hohmann transfer rime and delta-velocity equations from more general equations, which are obtained using Lambert's theorem. We note the tradeoff between minimum-time and - fuel transfer. An optimal coplanar orbit maneuver algorithm to trade off the minimum-time goal against the minimum-fuel goal is proposed. Finally, the numerical simulation results are given to demonstrate the derived theory and the algorithm.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.80-87
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• 2013

Communication Ocean Meteorological Satellite (COMS) has the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service. The COMS is located at $128.2{\circ}$ east longitude on the geostationary orbit and currently under normal operation service since April 2011. In order to perform the three missions, the COMS has 3 separate payloads, the meteorological imager (MI), the Geostationary Ocean Color Imager (GOCI), and the Ka-band communication payload. The satellite controls for the three mission operations and the satellite maintenance are done by the real-time operation which is the activity to communicate directly with the satellite through command and telemetry. In this paper the real-time operation for COMS is discussed in terms of the ground station configuration and the characteristics of daily, weekly, monthly, seasonal, and yearly operation activities. The successful real-time operation is also confirmed with the one year operation results for 2011 which includes both the latter part of the In-Orbit-Test (IOT) and the first year normal operation of the COMS.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.51-56
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• 2002

Satellite propulsion system is employed for orbit transfer, orbit correction, and attitude control. The monopropellant feeding system in the low-earth-orbit satellite blowdowns fuel to the thrust chamber. The thrust produced by the thruster depends on fuel amount flowed into the combustion chamber. If the thruster valve be given on-off signal from on-board commander in the satellite, valve will be opened or closed. When the thrusters fire fuel flows through opened thruster valve, instantaneous stoppage of flow in according to valve actuation produces transient pressure due to pressure wave. This paper describes transient pressure predictions of the KOMPSAT-2 propulsion system resulting from latching valve and thrust control valve operations. The time-dependent set of the fluid mass and momentum equations are calculated by MOC.

• Journal of Astronomy and Space Sciences
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• v.19 no.3
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• pp.197-206
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• 2002

NORAD Two Line Elements (TLE) are widely used for the increasing number of small satellite mission operations and analysis. However, due to the irregular periodicity of generation of the NORAD TLE, a new TLE that is independent of NORAD is required. A TLE type Orbit Determination (TLEOD) has been developed for the generation of a new TLE. Thus, the TLEOD system can provide an Antenna Control Unit (ACU) with the orbit determination result in the type of a TLE, which provides a simple interface for the commercialized ACU system. For the TLEOD system, NORAD SGP4 was used to make a new orbit determination system. In addition, a least squares method was implemented for the TLEOD system with the GPS navigation solutions of the KOMPSAT-1. Considering both the Orbit Propagation (OP) difference and the tendency of $B^{*}$ value, the preferable span of the day in the observation data was selected to be 3 days. Through the OD with 3 days observation data, the OP difference was derived and compared with that of Mission Analysis and Planning (MAPS) for the KOMPSAT-1. It has the extent from 2 km after sit days to 4 km after seven days. This is qualified enough for the efficiency of an ACU in image reception and processing center of the KOMPSAT-2.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.84-96
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• 2002

The major goal of this research is to use as a baseline guide for a flight model design of power system of next domestic communication satellite. For this purpose, the EPS(Electrical Power Subsystem) is designed to compliance performance requirements specified in EPS subsystem specification during all expected spacecraft operations. The regulated electrical power bus gives 42.5V to the various spacecraft loads from PCDU(Power Control & Distribution Unit) and the solar arrays are composed of 6 panel, each panel has 3 circuits including 7 string. The battery system is comprised of two batteries consisting of 26 IPV(Individual-Pressure-Vessel) NiH2 cells. Each battery can be capable of delivering 2878Watt-hours at a 80% maximum DOD(Depth of Discharge) based on the nameplate capacity of 150 amper-hours.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.4
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• pp.15-23
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• 2004

In order to utilize remote sensed images effectively, it is necessary to correct geometric distortion. Geometric correction is a critical step to remove geometric distortions in satellite images. For geometric correction, Ground Control Points (GCPs) have to be chosen carefully to guarantee the quality of geocoded satellite images, digital maps, GPS surveying or other data. Traditional approach to geometric correction used GCPs requires substantial human operations. Also that is necessary much time and manpower. In this paper, we presented an on-line automatic geometric correction by constructing GCP Chip database. The Proposed on-line automatic geometric correction system is consists of four part. Input image, control the GCP Chip, revision of selected GCP, and output setting part. In conclusion, developed system reduced the processing time and energy for tedious manual geometric correction and promoted usage of Landsat imagery.