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전동익,오화석,이상철,변상균,박종승,강민영,이승우,Cheon, Dong-Ik,Oh, Hwa-Suk,Lee, Sangchul,Byun, Sang-Kyun,Park, Jong-Seung,Kang, Min-Young,Rhee, Seung-Woo 항공우주시스템공학회 2007 항공우주시스템공학회지 Vol.1 No.4
Labyrinth seal is most common way to protect the bearings installed in Reaction wheel. In spite of wide applications, no such research was found about the sealing utility of the Labyrinth seal in the condition of vacuum and high temperature. In this research, we tried to verify the utility of Labyrinth seal. Numerical analysis had been executed to predict the benefit of the Labyrinth seal and also experiments were performed to verify the utilization. Two Bearings were installed at the vacuum chamber, one was assembled with Labyrinth seal and the other was stand alone. After executing the vacuum test, it was found to be the stand alone bearing had lost more weight than the one that was assembled with the labyrinth seal. In this result, it is verified that the Labyrinth seal has useful function to preserve the lubricant that affects to the life-cycle of the Bearing.
전절권 분포형 권선을 통한 제어모멘트자이로 김블의 저속 안정성 개선 연구
이준용,이헌조,오화석,송태성,강정민,송덕기,서중보,Lee, Jun-yong,Lee, Hun-jo,Oh, Hwa-suk,Song, Tae-Seong,Kang, Jeong-min,Song, Deok-ki,Seo, Joong-bo 항공우주시스템공학회 2019 항공우주시스템공학회지 Vol.13 No.3
전자기적 힘에 의해 김블 모터에 토크가 발생하며 코일 전류 변화는 토크 리플을 야기한다. 이는 김블속도에 영향을 주는 동시에 위성의 자세를 불안정하게 한다. 따라서 위성의 자세 제어 정확도 향상을 위해서는 김블 모터의 토크 리플 저감이 필수적이다. 본 논문에서는 일반적인 집중형 권선과 분포형 권선에 대해 모터의 모델링으로부터 발생 토크를 이론적으로 시뮬레이션 분석하였다. 토크 리플을 저감하는 권선을 선정하여 시제품을 설계 및 제작하여 자기장 및 역기전력의 이론적 해석 결과와 측정 결과를 비교하여 설계와 제작의 합치성을 확인하였다. 저속 시험을 통해 전절권 분포형 권선의 속도 안정도가 향상되어 토크 리플이 저감됨을 입증하였다. The electromagnetic forces generate a torque on the gimbal motor, and changes in the coil current causes torque ripple. This affects the gimbals' speed and results to unstable satellite attitude. It is therefore essential to reduce the torque ripple of the gimble motor with the aim of improving the attitude control accuracy of the satellite. This paper theoretically analyzes the torque generated from the modeling of a motor for general concentrated winding and distributed winding. The prototype was designed and fabricated through selection of the winding that reduces the torque ripple through simulation results. The results of the magnetic fields' theoretical analysis and the back electromotive force of the prototype were compared with the calibrated results for verification of conformity and manufacture of the design. The low-speed test proved that the torque ripple is reduced by improving the speed stability.
김동훈,전동익,오화석,이상철,방효충,이승우,Kim, Dong-Hoon,Cheon, Dong-Ik,Oh, Hwa-Suk,Lee, Sangchul,Bang, Hyochoong,Rhee, Seung-Wu 항공우주시스템공학회 2007 항공우주시스템공학회지 Vol.1 No.3
When the reaction wheel rotates, the disturbance occurs mainly due to the mass imbalance. It is necessary to predict the effect of disturbance on the attitude stability of the satellite. The disturbance forces and torques are identified and the attitude jitter of the satellite is analyzed depending on the configuration of the wheels. On the analysis the equation of the satellite motion is combined with the translational and rotational dynamics of the wheels. The accuracy of analysis is verified by simulation of STSAT-3 satellite.
모멘텀 휠의 내부 진공 유지를 위한 커넥터 밀봉방법 개발
전동익,공성철,오화석,이승우,Cheon, Dong-Ik,Gong, Sung-Chul,Oh, Hwa-Suk,Lee, Seung-Wu 항공우주시스템공학회 2008 항공우주시스템공학회지 Vol.2 No.4
In general, we utilize momentum wheel to control spacecraft. It needs vacuum test to analyze the effect of space environments. The conventional vacuum connector which is composed of steel has problems for test with built in momentum wheel because of weight, thermal expansion, etc. We suggest possibility to manufacture the vacuum connector using aluminum mount, epoxy and industrial D-Sub considering cost, weight. We verify the performance through vacuum test.
이상욱,김동훈,전동익,오화석,김응현,김규선,Lee, Sang-Wook,Kim, Dong-Hoon,Cheon, Dong-Ik,Oh, Hwa-Suk,Kim, Eung-Hyun,Kim, Gyu-Sun 항공우주시스템공학회 2008 항공우주시스템공학회지 Vol.2 No.1
The line of sight(LOS) is affected by the vibration of spacecraft. It is necessary to predict the effect of disturbance on LOS stability. Reaction wheel assembly is anticipated to be the largest disturbance source on spacecraft. The disturbance which is occurred mainly due to the mass imbalance is analyzed with harmonic numbers. The accuracy and stability are verified by probability density function with dynamic equation of the satellite motion.
SCL EM 반작용 휠의 시간응답 최적화를 위한 비례 이득 추정
김준호,이상욱,전동익,오화석,Kim, Joon-Ho,Lee, Sang-Wook,Cheon, Dong-Ik,Oh, Hwa-Suk 항공우주시스템공학회 2009 항공우주시스템공학회지 Vol.3 No.4
The driver's speed control to the satellite's mission is required. Therefore, optimal control over the value of benefits is required. Driver to control the characteristics of the driver and the driver was analyzed. Experimental results based on the estimated parameters using the equations of motion and was passed to save the function. Using optimization techniques applied to estimate the proportional term gain was the result of the analysis.