• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.45-54
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• 2010

The goal of the paper is to discuss the recent trend of the configuration of high resolution LEO(Low Earth Orbit) EO(Earth Observation) satellites. The satellite configuration is decided by considering several factors such as mission, payloads, launch vehicle, propulsion and attitude control module. The advent of commercial companies selling satellite's images in 2000's requires additional changes of the satellite system to be capable of obtaining many high resolution images quickly. In order to meet customer's needs, the overall configuration of satellites is designed to be compact and stable without the loss of structural integrity and reliability. Among design changes, the configuration change of satellites is treated intensively in the paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.517-524
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• 2019

A system design has been performed for a vacuum thrust 88 ton staged combustion cycle rocket engine. Previous research has been used to estimate the performance of the engine components. And the algorithm has been proposed to evaluate the converged engine system performance. The present methodolgy has been verified by comparing the published data for RD-180. The present work adopts the most of the previous KSLV-II engine heritage for both performance improvement and cost competitiveness. The combustion pressure has been decided as 12MPa considering manufacturing difficulty, cost and performance improvement, and as a result the vacuum specific impulse has increased by 23.4s.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.11-20
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• 2024

In the recent era of NewSpace, unlike high-reliability satellites of the past, low-reliability satellites are being developed and mass-produced at a lower cost to launch constellations satellites. To achieve cost-effective cluster satellite development, satellite users and developers need to assess the feasibility of maintaining mission performance over the expected lifespan when cluster satellites are launched. Plans for replacements due to random failures should also be established to maintain performance. This study proposed a method for assessing system reliability and availability to maintain mission performance and establish replacement strategies for Earth observation constellation satellites. In this study, a constellation reliability and availability model considering mission performance required for a satellite constellation, situations of satellite backup, and additional ground backups was established. The reliability model was structured based on the concept of a k-out-of-n system and the availability model used a Markov chain model. Based on the proposed reliability model, the minimum number of satellites required to meet mission requirements was defined and satellites needed in orbit during the required mission period to satisfy mission reliability were calculated. This research also analyzed the number of spare satellites in orbit and on the ground required to meet the desired availability during required service period through availability analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.311-318
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• 2014

Electromagnetic compatibility(EMC) performance of the first Korea space launch vehicle(KSLV-I) should be ensured and verified in order to guarantee the normal operation among the spacecraft, ground facilities which are installed in the space center, and other wireless communication networks. For the purpose of the EMC performance verification, pertinent EMC test specifications, methods, and procedures for both the subsystems and the system should be established in consideration of operational properties and electromagnetic environmental effects. And it is required to maintain and control the EMC properties consistently in accordance with the determined specifications up to the program closing phase. In this paper, sequential management work conducted during the overall development process of the KSLV-I is explained, and not only the phased EMC test plan for each model of the KSLV-I and its subsystem but also test method, specification, and results of the verification tests are presented. And also, multipaction analysis results are presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.333-342
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• 2016

Liquid rocket propulsion is a system that produces required thrust for satellites and space launch vehicles by using chemical reactions of a liquid fuel and a liquid oxidizer. Monomethylhydrazine/dinitrogen tetroxide, liquid hydrogen/liquid oxygen and RP-1/liquid oxygen are typical combinations of liquid propellants commonly used for the liquid rocket propulsion system. The objective of the present study is to investigate useful design and performance data of liquid rocket engine by conducting a numerical analysis of thermochemical reactions of liquid rocket propellants. For this, final products and chemical compositions of three liquid propellant combinations are calculated using equilibrium constants of major elementary equilibrium reactions when reactants remain in chemical equilibrium state after combustion process. In addition, flame temperature and specific impulse are estimated.

• Journal of Aerospace System Engineering
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• v.14 no.spc
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• pp.49-55
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• 2020

The average probability of a lightning strike to transport aircraft operating in airline service has been estimated to be approximately one strike in every year (or one strike per 1,000 through 20,000 flight hours). The important thing is not the probability of a lightning strike to aircraft, but the fact that aircraft is struck by lightning. Therefore, lightning protection design for aircraft should be qualified and compliance with airworthiness standards related to lightning protection must be substantiated in the process of certification. In this paper, I studied means of compliance for lightning protection through analysis of some test cases, including the KC-100 airplane that firstly obtained civil type certificate in Korea. Based on this paper, it will be also necessary to study on the effect of lightning for space launch vehicles.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.125-132
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• 2010

Estimation of pressurant mass flowrate and its total mass required to maintain propellant tank pressure during propellant outflow is very important for design of pressurization control system and pressurant storage tank. Especially, more pressurant mass is required to maintain pressure in cryogenic propellant tank, because of reduced specific volume of pressurant due to heat transfer between pressurant and tank wall. So, basic model for propellant tank ullage calculation was proposed to estimate ullage and tank wall temperature distribution, required pressurant mass, and energy distribution of pressurant in ullage. Both test and theoretical analysis have been conducted, but only theoretical modeling method was addressed in this paper.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.189-199
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• 2013

This paper summarizes results of second stage attitude control of KSLV-I third flight test. The results show that three axes attitude control at coasting phases of KSLV-I was successfully accomplished by the reaction control system, and pitch and yaw attitude control at thrusting phase where second stage kick motor burns was also normally accomplished by using the thrust vector control system. It is verified that the second stage controller performed successfully for all flight phases regardless of some disturbances due to mass center offset, slag effects, and residual thrust of kick motor. These results may provide an important basis in enhancing domestic technology level of attitude control of launch vehicle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.111-117
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• 2004

An analytical study was carried out to evaluate the regenerative cooling characteristics in the liquid rocket engine of a 10tf-thrust level using kerosene as a fuel. As a supplementary cooling method, a radiative cooling was applied to the nozzle extension. It was found out from this work that the cooling system with the regenerative and radiation cooling only is not adaptable for the liquid rocket engine of a 10tf-thrust level using kerosene as a fuel for the $2^{nd}$ stage of the space launch vehicle, with the viewpoint of the thermal and thermo-structural instability and the excessive pressure drop in the cooling channel.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.17-22
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• 2006

Anhydrous hydrazine and its methyl derivatives MMH and UDMH have been safety used as monopropellant and bipropellant fuels in thousands of satellites and expendable launch vehicles. Since KOMPSAT program, We have been developing skills on the hydrazine propulsion system for several years. This paper presents an overview of the hydrazine for the space application - propellant overview, material compatibility, handling cautions and the future of hydrazine systems.