http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
분류 알고리즘과 NCA를 활용한 기계학습 기반 구조건전성 모니터링 시스템
신창교,권혁석,박유림,김천곤 한국항행학회 2019 韓國航行學會論文誌 Vol.23 No.1
This is a pilot study of machine learning based structural health monitoring system using flight data of composite aircraft. In this study, the most suitable machine learning algorithm for structural health monitoring was selected and dimensionality reduction method for application on the actual flight data was conducted. For these tasks, impact test on the cantilever beam with added mass, which is the simulation of damage in the aircraft wing structure was conducted and classification model for damage states (damage location and level) was trained. Through vibration test of cantilever beam with fiber bragg grating (FBG) sensor, data of normal and 12 damaged states were acquired, and the most suitable algorithm was selected through comparison between algorithms like tree, discriminant, support vector machine (SVM), kNN, ensemble. Besides, through neighborhood component analysis (NCA) feature selection, dimensionality reduction which is necessary to deal with high dimensional flight data was conducted. As a result, quadratic SVMs performed best with 98.7% for without NCA and 95.9% for with NCA. It is also shown that the application of NCA improved prediction speed, training time, and model memory. 본 연구는 복합재 항공기의 비행 데이터를 활용한 기계학습 기반 구조건전성 모니터링 시스템 연구의 예비 연구이다. 본 연구에서는 구조건전성 모니터링에 이용되기에 가장 적합한 기계학습 알고리즘을 선별하고, 실 기체 데이터에 대한 적용을 위해 차원 축소를 수행하였다. 이를 위해 외팔보를 통해 모사된 항공기 날개 구조와 부가 질량을 통해 손상 모사 실험을 진행하고, 분류 알고리즘을 통해 데이터를 손상의 위치와 정도에 따라 구분하였다. 이를 위해 FBG (fiber bragg grating) 센서를 부착한 외팔보의 진동 실험을 통해 정상상태와 12개의 손상상태에 대한 데이터를 취득하고, MATLAB 환경에서 tree, discriminant, SVM (support vector machine), kNN, ensemble 알고리즘의 비교와 파라미터 튜닝을 통해 가장 적합한 알고리즘을 도출하였다. 또한 NCA (neighborhood component analysis)를 이용한 특징 선택을 통해, 실 기체에서 나올 수 있는 고차원 데이터의 관리를 위해 필요한 차원 축소를 수행하였다. 그 결과, quadratic SVM이 NCA를 적용하지 않은 모델에서 98.7%, NCA를 적용한 모델에서 95.9%로 가장 높은 정답률을 보였다. 또한 NCA 적용 후 모델의 예측 속도, 학습 시간, 용량이 모두 향상되었다.
신창교,김건중 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2
The syntheses of optically pure chemicals have gained significant potential over recent years. Chiral catalysts get more important nowadays. Especially the heterogeneous chiral catalysts offer practical advantages of the facile separation from reactants and products. Several immobilization strategies have been shown to give stable and active heterogeneous catalysts. So, we synthesize chiral Co(III) salen complexes bearing on BCl3. And this Co(III) Salen complexes are immobilized on the functionalized silica gel. This catalysts are very reactive and enantioselective in the hydrolytic kinetic resolution of racemic ECH(epichlorohydrine) with water.
권현석,박유림,신창교,김진혁,김천곤 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.3
With the increased use of composite materials in aircraft structures, continuous and thorough monitoring of structural conditions is highly required for the assurance of safety and reliability. In this study, as part of the fiber Bragg grating (FBG) sensor-based aircraft health and usage monitoring system (HUMS) development research, in-flight strain monitoring of an aircraft tail boom structure using the FBG sensor-based aircraft HUMS was investigated. The FBG sensor-based aircraft HUMS was implemented to the tail boom structure of an ultralight propeller composite aircraft. Flight tests of the testbed aircraft were performed, and in-flight strain variations of the tail boom structure were measured using the implemented system. For in-flight strain variation data-based verification through comparative analysis with flight parameters, the in-flight strain variations of the tail boom structure were analyzed with the flight parameters for various flight conditions. As a result, the HUMS operated as expected during the actual flights, and the acquired in-flight strain variations corresponded adequately in relation to the loading conditions during flight, such as bending loads due to the use of control surfaces and ground impacts during landing procedures.