• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.697-700
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• 2011

본 논문에서는 X-FEM을 사용하여 혼합모드 하중 상태에서의 이차원 선형탄성체의 균열문제에 대한 형상 설계민감도 해석을 수행하였다. X-FEM이란 균열과 같은 특수한 해를 근사하는 방법으로써, 확장함수를 도입하여 FEM의 한계를 극복하는 방법론이다. X-FEM 하에서 해를 근사하는 데 쓰이는 확장함수들은 불연속성과 특이성을 포함하고 있어 물리적 영역에 의존한다. 이는 설계민감도 해석을 수행하는 과정에서 그러한 의존성을 고려해주는 것이 필요하다. 따라서 본 논문에서는 X-FEM 기반의 형상 설계민감도 해석해를 제안하고자 한다. 식의 유도는 전 미분 공식에 기초하고 있으며, 형상함수의 설계변분에 대한 의존성에 관한 항을 추가시켰다. 또한, 균열 주위의 국부적인 공간에서의 확장된 자유도에 설계속도를 가한다. 이에 대한 몇 가지 수치 예제를 통하여 개발된 방법론의 타당성을 확인하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.12-20
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• 2002

To control the noise of an enclosed sound field, we built a state space model using the acoustic modal parameter description. Using the state space model, we can investigate the controllability and observability, and find an appropriate position of control speaker and microphone to control sound field of the enclosed space. We implemented LQR(linear quadratic regulator) controller and reduced order observer to reduce the first acoustic mode. Experiments showed satisfactory results of 4∼10 dB reduction of magnitude of the first acoustic mode, and support the feasibility of the proposed scheme to lightly damped acoustic field.

• Composites Research
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• v.36 no.3
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• pp.230-240
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• 2023

The deployable reflector antenna consists of 24 unit main reflectors, and is mounted on a launch vehicle in a folded state. This satellite reaches the operating orbit and the antenna of satellite is deployed, and performs a mission. The deployable reflector antenna has the advantage of reduce the storage volume of payload of launch vehicle, allowing large space structures to be mounted in the limited storage space of the launch vehicle. In this paper, structural analysis was performed on the main reflector constituting the deployable reflector antenna, and through this, the initial conceptual design was performed. Lightweight composite main reflector was designed by applying a carbon fiber composite and honeycomb core. The laminate pattern and shape were selected as design variables and a design that satisfies the operation conditions was derived. Then, the performance of the lightweight composite reflector antenna was analyzed by performing detailed structural analysis on modal analysis, quasi-static, thermal gradient, and dynamic behavior.