• Proceedings of the KSME Conference
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• 2003.11a
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• pp.163-168
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• 2003

Analytical approach is applied to predict temperature of satellite box under worst hot condition from fairing jettison to separation. The box is tried to solve analytically which is exposed to known environmental heating condition and has internal heating and irradiation to space. For a single thermal mass, governing equation for temperature is simplified to 1st order ordinary differential equation(ODE) by several assumptions. Two cases are considered. The one is for constant mass box and the other is for mass-varying box. Each case has three different analytical solution by sign of constant term in ODE. One analytical solution for constant mass is applied to physical launch stage condition. It is concluded that the present analytical method can be used to quick predict the temperature of a satellite box and check whether a satellite is safe against space environment during launch stage.

• Journal of Communications and Networks
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• v.9 no.2
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• pp.159-166
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• 2007

In this paper, we propose an efficient and robust interference mitigation technique based on a nullsteering multi-user multiple-input multiple-output (MU-MIMO) spatial division multiple access (SDMA) scheme for frequency sharing between IMT-advanced and fixed satellite service (FSS) in the 3400-4200 and 4500-4800 MHz bands. In the proposed scheme, the pre-existing precoding matrix for SDMA unitary precoded (UPC) MIMO proposed by the authors is modified to construct nulls in the spatial spectrum corresponding to the direction angles of the victim FSS earth station (ES). Furthermore, a numerical formula to calculate the power of the interference signal received at the FSS ES when IMT-Advanced base stations (BS) are operated with the interference mitigation technique is presented. This formula can be derived in closed form and is simply implemented with the help of simulation, resulting in significantly reduced time to obtain the solution. Finally, the frequency sharing results are analyzed in the co-channel and adjacent channel with respect to minimum separation distance and direction of FSS earth station (DOE). Simulation results indicate that the proposed mitigation scheme is highly efficient in terms of reducing the separation distance as well as robust against DOE estimation errors.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.345-354
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• 2011

Earth acquisition is to solve when earth can be visible from satellite after Sun acquisition during launch and early operation period or on-station satellite anomaly. In this paper, the algorithm and test result of the Communication, Ocean and Meteorological Satellite (COMS) Earth acquisition are presented in case of on-station satellite anomaly status. The algorithms for the calculation of Earth-pointing attitude control parameters including those attitude direction vector, rotation matrix, and maneuver time and duration are based on COMS configuration (Eurostar 3000 bus). The coordinate system uses the reference initial frame. The constraint calculating available time-slot to perform the earth acquisition considers eclipse, angular separation, solar local time, and infra-red earth sensor blinding conditions. The results of Electronics and Telecommunications Research Institute (ETRI) are compared with that of the Astrium software to validate the implemented ETRI software.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.2
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• pp.17-25
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• 2003

Simple methods are developed to predict temperatures of a satellite box during launch stage. The box is mounted on outer surface of satellite and directly exposed to space thermal environment for the time period from fairing jettison to separation. These simple methods are to solve a 1st order ordinary differential equation (ODE) which is simplified from the governing equation after applying several assumptions. The existence of analytical solution for the 1st order ODE is determined depending on treatment of time-dependent molecular heating term. Even for the case that the analytical solution is not available due to the time dependent term, the 1st order ODE can be solved by relatively simple numerical techniques. The temperature difference between two different approaches (analytical and numerical solutions) is relatively small (Jess than $1^{\circ}C$ along the time line) when they are applied to STSAT-I launch scenario. The present methods can be generally used as tools to quickly check whether a satellite box is safe against space environment during the launch stage for the case that the detailed thermal analysis is not available.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.519-527
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• 2023

Air-launch means launching from aircraft such as fighter jets, and has various advantages, such as cost reduction and less environmental/weather impact during launch. However, there are no air-launch satellite in Korea. Examining air-based launch satellite and anti-satellite missiles operated and developed by foreign private companies and various countries confirmed the necessity of domestic research and development. In South Korea, various research activities, including satellite launch system design and development approaches for different launch platforms, have been carried out mainly by academia. Development of upward maneuver air launch technology which is launched in the air when the aircraft is moving upward is suggested. Additionally, an introduction to wind tunnel tests for safety separation verification is provided. A new concept for a test facility has been suggested to conduct drop tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.520-521
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• 2013

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.457-463
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• 2009

This paper describes the development of non-explosive separation(NES) device which can be equipped on a small satellite. It comprises mechanism itself and spring-type shape memory alloy(SMA) actuator. In order to design SMA actuator properly, the necessary actuation force is measured. Based on that result, SMA actuator is designed and fabricated. Finally, SMA actuator and the proposed mechanism are integrated. In order to evaluate performance of the developed NES, we carried out a response time test, preload test and shock level test. In near future, we expect to replace the imported NES device with the developed device.

• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.58-62
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• 2016

The satellite propulsion system provides the required thrust to insert a satellite into the desired orbit after separation from the launch vehicle and to control orbit inclination or compensate altitude loss due to drag after inserted into the desired orbit. The on-orbit performance of LEO satellite propulsion system according to operation mode was verified based on the results analysis for early on-orbit operation. The temperature trends of components and tubing were checked and the resultant trends were within the normal range as well.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.199-208
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• 1999

In this paper, KOMPSAT satellite launch and deployment operations are discussed. The U.S. Taurus launch vehicle delivers KOMPSAT satellite into the mission orbit directly. Launch and deployment operations is monitored and controlled by several international ground stations including Korean Ground Station (KGS). After separation from launch vehicle, KOMPSAT spacecraft deploys solar array by on-board autonomous stored commands without ground inter-vention and stabilizes the satellite such that solar arrays point to the sun. Autonomous ground communication is designed for KOMPSAT for the early orbit ground contact. KOMPSAT space-craft has capability of handing contingency situation by on-board fault management design to retry deployment sequence.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.194-201
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• 2008

The launch vehicle upper stage generally executes collision and contamination avoidance maneuver after the satellite separation. Through this maneuver the satellite safely settles in its orbit and the launch vehicle moves away from the satellite with minimum contamination. In this paper collision and contamination avoidance maneuvers by foreign launch vehicles are analyzed. Criteria for satellite contamination during the avoidance maneuver is given for KSLV-I upperstage.