• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.393-402
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• 2003

The Multi-Spectral Camera (MSC) is the payload of KOMPSAT-2 which is designed for earth imaging in optical and near-infrared region on a sun-synchronous orbit. The telescope in the MSC is a Ritchey-Chretien type with large aperture. The telescope structure should be well stabilized and the optical alignment should be kept steady so that best images can be achieved. However, the MSC is exposed to adverse thermal environment on the orbit which can give impacts on optical performance. Solar incidence can bring non-uniform temperature rise on the telescope tube which entails unfavorable thermal distortion. Three ways of preventing the solar radiation were proposed, which were installing external mechanical shield, internal shield, and maneuvering the spacecraft. After trade-off study, internal sun shield was selected as a practical and optimal solution to minimize the effect of the solar radiation. In addition, detailed designs of the structure and sunshield were produced and analyses have been performed. The results were assessed to verify their impacts to the image quality. It was confirmed that the internal sunshield complies with the requirements and would improve image quality.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.815-820
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• 2002

MSC as a payload of KOMPSAT-2 is an optical telescope for earth imaging on a sun-synchronous orbit. The MSC is a Ritchey-Chretien type telescope composed of hyperbolic primary and secondary mirrors with focal correcting lenses. Their relative positions should be kept aligned during imaging operation. However, the MSC is exposed to adverse thermal environment on orbit which can have some impacts on optical performance as well as structural endurance. Solar incidence can cause non-uniform temperature rise on the tube which entails unfavorable thermal distortion. Three options were proposed, which were internal shield, external mechanical shield and spacecraft maneuvering. After the trade-off studies, internal sun shield was selected as a realistic and optimal solution to minimize the effect of the solar radiation. In this paper, pros and cons are explained for the three possible choices and a design of the internal shield is discussed.

• Advances in aircraft and spacecraft science
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• 제7권3호
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• pp.251-269
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• 2020

Euclid is an optical/near-infrared survey mission of the European Space Agency (ESA) to investigate the nature of dark energy, dark matter and gravity by observing the geometry of the Universe and the formation of structures over cosmological timescales. The Euclid spacecraft mechanical architecture comprises the Payload Module (PLM) and the Service Module (SVM) connected by an interface structure designed to maximize thermal and mechanical decoupling. This paper shortly illustrates the mechanical system of the spacecraft and the mechanical verification philosophy which is based on the Structural and Thermal Model (STM), built at flight standard for structure and thermal qualification and the Proto Flight Model (PFM), used to complete the qualification programme. It will be submitted to a proto-flight test approach and it will be suitable for launch and flight operations. Within the overall verification approach crucial mechanical tests have been successfully performed (2018) on the SVM platform and on the sunshield (SSH) subsystem: the SVM platform static test, the SSH structure modal survey test and the SSH sine vibration qualification test. The paper reports the objectives and the main results of these tests.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권2호
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• pp.146-155
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• 2004

현재 대부분의 상용 운영체제는 운영체제의 보안성을 높이기 위하여 높은 수준의 감사 기능을 제공한다. Linux의 성능 및 안정성은 기존 상용 운영체제에 뒤떨어지지 않지만, 감사 기능을 거의 제공하지 못하고 있다. Linux를 서버 운영체제로 사용하기 위해서는 C2 수준 이상의 보안성을 필요로 하며, 이를 만족시키기 위해서는 시스템 콜에 대한 감시와, 감사 이벤트가 요구된다. 본 논문의 LxBSM은 Linux 커널에서 C2 수준의 감사 기능을 제공하는 커널 모듈이다. LxBSM은 SunShield BSM의 감사 자료와 호환되는 C2 수준의 감사 자료를 제공하며, 동적 커널 모듈(Loadable Kernel Module) 방식으로 구현되어 운용성을 높였다. 또한 사용자 프로세스에 대한 감사 자료를 생성함으로써, 기존의 Linux 기반 감사 모듈보다 풍부한 감사 자료를 제공한다. 파이프와 파일로 감사 자료의 출력이 가능하여 감사 자료를 활용하는 침입 탐지 시스템의 연계성을 높였다. LxBSM의 성능을 측정한 결과, fork, execve, open, close와 같이 감사 자료를 생성하는 시스템 콜이 호출될 때의 응답 시간은 지연되었으나, 그 외의 다른 성능 감소 현상은 나타나지 않았다.