• 항공우주시스템공학회지
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• 제15권4호
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• pp.40-46
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• 2021

At launch, satellites are exposed to various types of structural loads, such as quasi-static loads, sinusoidal vibrations, acoustic/random vibrations, and shocks. The launch environment test is aimed at verifying the structural stability of the test object against the launch environment. Various types of launch environments are simulated by simple vibration, acoustic, and shock tests considering possible test conditions in ground. However, the difference between the launch environment and the test environment is one of the causes of excessive testing. To prevent overtesting, a notching technique that adjusts the frequency range and the input load considering the design load is applied. For notching, specific procedures are established considering the satellite development concept, selected launch vehicle, higher system requirements, and test target level. In this study, the notching method, established procedure, and development of a notching toolkit for efficient testing are described.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1234-1239
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• 2000

KOMPSAT-1(Korea Multi-Purpose Satellite), which opened the space era in Korean peninsula, was developed from 1994 and launched successfully in December of 1999 at VAFB, USA. This paper presents a launch environment test of KOMPSAT and a short description of environment test facilities at Korea Aerospace Research Institute as well. The launch environment tests of KOMPSAT-1 satellite, such as vibration, acoustic, pyro-shock and mass properties measurement test, were performed during its system integration and test period. The participating engineers concluded that KOMPSAT-1 satellite would withstand environment during its launch period.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1252-1258
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• 2000

Koreasat-3 was successfully launched by an Ariane IV launch vehicle on September 5, 1999. Although the primary purpose of the satellite is to replace Koreasat-l, it also can extend its communication service coverage over the Asia-Pacific region. A spacecraft is subjected to severe dynamic loads during launch period. To verify the safety of spacecraft under the launch environment, dynamic tests should be performed such as sine sweep, acoustic and separation shock tests. This paper presents the launch environment test results of Koreasat-3. A total of 188 acceleration responses was measured and compared with the design requirements of components and spacecraft. Dynamic characteristic change was also investigated by comparing between low-level pre/post vibration results. From the review of test results, it is concluded that Koreasat-3 was designed and manufactured with the margin of safety enough to survive the launch loads of Ariane IV.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.747-750
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• 2004

After launching, spacecraft is exposed to extreme environments. So spacecraft should be tested after design/manufacture to verify whether components can be operated functionally. Acceleration transferred from launch vehicle to spacecraft produces quasi-static load, sine vibration and random vibration. Random vibration is also induced by acoustic vibrations transferred by surface of spacecraft. And shock vibration is produced when spacecraft is separated from launch vehicle. To verify operation of spacecraft under these launch environments, separation shock test, sine vibration test, acoustic vibration test and random vibration test should be performed. This paper describes these launch environment test requirements.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.273-278
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• 2006

In order to use a GPS antenna for launch vehicles, it should be installed on the skin of the vehicle and be able to normally receive the live GPS signals during the vehicle's full flight mission. The GPS antenna on the surface of the launch vehicle is, however, exposed to higher temperature than inner equipments of the vehicle due to aerodynamic heating generated during the flight. Test specification of the GPS antenna for qualification of hot-temperature is determined to $+95^{\circ}C$ that is higher than inner components by $25^{\circ}C$. Test results in this paper show that the GPS antenna normally operates under the above environment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.258-262
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• 2007

Satellite launch vehicle is exposed to some dynamic environment during its flight. Particularly, the safety of launch vehicle structure is surely verified under vibration environment in low frequency range. Sine sweep test is generally performed to describe this low frequency vibration environment. Dynamic property of vibration fixture is considered to get the correct property of target object. This vibration fixture should really be an extension of the armature in the form of a very rigid structure that can transfer the required force at the required frequency. An optimum fixture would have its lower natural frequency about 50% higher than the highest required forcing frequency in order to avoid fixture resonances during the test. In this study, the vibration mode analysis considering the mass of target object to design the vibration fixture. And the modal test of vibration fixture is performed to conform the design.

• 한국소음진동공학회논문집
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• 제24권7호
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• pp.517-524
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• 2014

Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with mechanical moving parts affects the image quality of high-resolution observation satellite. Micro-vibration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism additionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vibration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

• Journal of Astronomy and Space Sciences
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• 제13권2호
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• pp.94-104
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• 1996

The satellite experiences the launch environment such as vibration, acceleration, shock induced by rocket and the orbit environment such as high vacuum, no gravity, high temperature and cryogenic. Therefore, the satellite should be designed and manufactured to endure such environments. Also, special care must be taken on the assembly of parts and subsystem. Finally, we describe the environment test of microsatellite to ensure the reliable operation during launch period as well as in-orbit operation.

• 한국항공우주학회지
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• 제42권12호
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• pp.1051-1056
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• 2014

소형인공위성에 적용을 목적으로 전기추진시스템의 연료공급부가 개발되었다. 연료공급부는 연료로 사용되는 제논을 높은 압력과 밀도의 가스상태로 저장하게 된다. 제논은 상온에서 임계점을 갖는데 발사환경에서 과도상태로 시스템에 영향을 미칠 수 있다. 따라서 발사환경에 대한 본 시스템의 기능적 구조적 안정성은 지상시험을 통한 검증이 필요하다. 본문에서는 연료공급부의 설계점과 검증시험내용을 논하고 시험결과를 정리하였다. 검증시험을 통해 본 시스템이 발사환경에 대하여 안정성을 확보하고 있는 것을 확인하였다.

• International Journal of Aeronautical and Space Sciences
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• 제4권2호
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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.