• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.2
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• pp.155-160
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• 2012

In this paper, a strip modeling method is developed for the acquisition of target positions in remote area and validated using the imagery of SPOT satellite. This method utilizes the parameters given in header files and constructs a camera model without ground control points. In most cases, the root mean squared error of check points is less than pixel size with one ground control point. The model error of reference image is evaluated using ground control points and used to remove the model error of target images acquired along the same satellite orbit, which enables one to calculate target positions in remote area where no ground control points are available.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.57-59
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• 2003

Digital surface model generation from IKONOS stereo imagery is a new challenge in photogrammetric community, especially when the satellite company does not provide the raw data as well as their ancillary ephemeris data. In this paper we utilized an estimated relief displacement azimuth and the nominal collection elevation data included in the metadata file to correct the relief displacement of GCPs, together with a linear transformation for geometric modeling of IKONOS imagery. Space intersection is performed by the trigonometric intersection assuming a parallel projection of IKONOS imagery due to its small FOV and frame size. In the experiment, less than 2-meters of RMSE in orbit modeling is achieved denoting the potential positioning accuracy of the IKONOS stereo imagery.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.187-195
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• 2008

Generation of accurate ground coordinates from high resolution satellite image are becoming increasingly of interest. The primary focus of this paper is to compute satellite direct sensor model (DSM) and rational function model (RFM) for accurate generation of ground coordinates from high resolution satellite images. Being based on this we presented an algorithm to be able to efficiently ground coordinates about large area with introducing RFM(rational function model) method applied to rigorous sensor modeling standing on basis of satellite orbit dynamics and collinearity equation, and sensor modeling of high-resolution satellite data like IKONOS, QuickBird, KOMPSAT-2 and others. The general high resolution satellite measures the position, velocity and attitude data of satellite using star, gyro, and GPS sensors.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.74-80
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• 2016

In this paper, the modeling and implementation results of the operational test and evaluation tool of the KASS up-link station composed of the GEO(Geostationary Earth Orbit) satellite signal analysis tool model that analyzes the GEO satellite signal and the GEO message analysis tool model that analyzes the GEO satellite navigation message. In addition, we describe the results of software modeling and implementation of some software models of GEO satellite and KASS up-link stations that can generate and provide simulated signals to operational test and evaluation tools of these KASS up-link stations.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.290-295
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• 2003

Among the thermal analysis methods for Multi-Layer Insulation(MLI), effective emittance, diffusion MLI node and arithmetic MLI node methods are compared. The methods have been applied to the aluminum panel under the low earth orbit environment. TRASYS program is used for geometrical math modeling and SINDA program for thermal math modeling and temperature calculation. Test cases are selected according to MLI area on the panel. Temperature results are calculated and compared under the ratio of absorptivity and emissivity.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.149-152
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• 2007

The horizontal geo-location accuracy of KOMPSAT-2, without GCPs (Ground Control Points) is 80 meters CE90 for monoscopic image of up to 26 degrees off-nadir angle, after processing including POD (Precise Orbit Determination), PAD(Precise Attitude Determination) and AOCS (Attitude and Orbit Control Subsystem) sensor calibration. In case of multiple stereo images, without GCPs, the vertical geometric accuracy is less than 22.4 meters LE 90 and the horizontal geometric accuracy is less than 25.4 meters. There are two types of sensor model for KOMPSAT-2, direct sensor model and Rational Function Model (RFM). In general, a sensor model relates object coordinates to image coordinates The major objective of this investigation is to check and verify the geometrical performance when initial KOMPSAT-2 images are employed and briefly introduce the sensor model of KOMPSAT-2.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.17-29
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• 1999

Inter-Satellite Links(ISL) technique in the Polar Orbit Satellite plays the key role in the communication methods in IRIDIUM system, where the ISL is commonly established between neighbor satellites. The system has major drawbacks in maintaining the multi-hopping link connectivities while the satellite nodes are communicating each other. The proposed system is newly designed to allow diagonal link connections between the satellites and shows how it does improve the performance. The optimized number of satellites in the terms of their altitudes and visible distance are calculated. The traffic parameters and the probability of blocking are analyzed to compare the visible satellite link method with the neighbor link method mathermatically.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.1
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• pp.77-88
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• 2015

The dynamics of relative motion in a perturbed orbital environment are exploited based on Gauss' and Cowell's variational equations. The inertial coordinate frame and relative coordinate frame (Hill frame) are used, and a linear high fidelity model is developed to describe the relative motion. This model takes into account the primary gravitational and atmospheric drag perturbations. Then, this model is used in the design of a navigation, guidance, and control system of a chaser vehicle to approach towards and to depart from a target vehicle in proximity operations. Relative navigation uses an extended Kalman filter based on this relative model to estimate the relative position/velocity of the chaser vehicle with respect to the target vehicle. This filter uses the range and angle measurements of the target relative to the chaser from a simulated LIDAR system. The corresponding measurement models, process noise matrix, and other filter parameters are provided. Numerical simulations are performed to assess the precision of this model with respect to the full nonlinear model. The analyses include the navigation errors and trajectory dispersions.

• 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.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.136-140
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• 2011

Satellites industry has been developing with the commercial and military needs. Because power system of satellites is very important to survival operation and hard to test, increasing reliability is very critical. Especially LEO small satellites are very sensitive to power system, effective stabilization control is important. Because of various need of load condition, converter design are complicated. Therefore this paper introduced general modeling of LEO small satellite converter system and analyzed stabilization control design. The performance prediction of LEO small satellites power system is typically critical. Because of verity controller and rectification value, it is hard to computation and test implementation. So, this approach has merit that will reduce cost and make more reliable system. Furthermore, it can be constraint of converter specification and controller design. This paper will examine generation a modeling of LEO small satellites power converting system, and a possible guide line to design reliable controller which optimizing power converters of LEO small satellite.