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김홍래(Hongrae Kim),정성근(Seong-keun Jeong),오현웅(Hyun-Ung Oh) 항공우주시스템공학회 2024 항공우주시스템공학회지 Vol.18 No.1
In the recent era of NewSpace, unlike high-reliability satellites of the past, low-reliability satellites are being developedand mass-produced at a lower cost to launch constellations satellites. To achieve cost-effective cluster satellite development, satellite users and developers need to assess the feasibility of maintaining mission performance over the expected lifespan when cluster satellites are launched. Plans for replacements due to random failures should also be established to maintain performance. This study proposed a method for assessing system reliability and availability to maintain mission performance and establish replacement strategies for Earth observation constellation satellites. In this study, a constellation reliability and availability model considering mission performance required for a satellite constellation, situations of satellite backup, and additional ground backups was established. The reliability model was structured based on the concept of a k-out-of-n system and the availability model used a Markov chain model. Based on the proposed reliability model, the minimum number of satellites required to meet mission requirements was defined and satellites needed in orbit during the required mission period to satisfy mission reliability were calculated. This research also analyzed the number of spare satellites in orbit and on the ground required to meet the desired availability during required service period through availability analysis.
양성자 조사 시험에 기초한 MPC860 소자의 SEE 발생률 예측
김성준(Sung-Joon Kim),선종호(Jongho Seon),정성근(Seong Keun Jeong),민경욱(Kyoung-Wook Min),최원호(Wonho Choe) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.5
양성자 가속기를 이용한 지상 실험에 기초하여 인공위성에서 사용할 마이크로프로세서의 SEE 발생률을 예측하였다. 우주 공간의 하전 업자 분포를 AP8, JPL91 그리고 CREME 모델을 사용하여 추정하고, 양성자 가속기를 통한 실험에서 얻어진 단면적 곡선들을 SEE 발생률 예측에 사용하였다. 약 685 ㎞의 저궤도에 대해 고 경사각과 저 경사각이 고려되었다. 계산 결과는 후보 소자에 대한 SEE 발생률이 저 경사각에서는 수용할만한 것이었지만 고 경사각의 경우에는 최악의 조건에서 문제될 수 있음을 보여준다. A prediction of SEE rates for a candidate microprocessor is made based on the ground experiment results with a proton accelerator. Populations of charged particles in space are estimated with numerical models such as AP8, JPL91 and CREME. The cross section curves that are previously obtained with the accelerator are then employed for SEE prediction. Both the high and low inclinations are considered for low-earth orbits with nominal altitudes of about 685 ㎞, The results show that the occurrence rate of SEEs for the candidate device is acceptable for low-inclinations, but can be considerable under worst conditions for high inclinations.
랜덤진동 환경하에 전장품 PCB 피로해석 방법론의 비교분석
노홍균(Hong-Kyun Noh),임재혁(Jae Hyuk Lim),권성철(Seong-Cheol Kwon),정성근(Seong-Keun Jeong),박태용(Tae-Yong Park),오현웅(Hyun-Ung Oh) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.10
자동차, 항공기, 인공위성, 발사체 등 첨단 운송체에 탑재되는 대부분의 전장품들은 다수의 인쇄회로기판(PCB)을 보유하고 있으며 운용환경 중에 랜덤진동에 의한 피로손상으로 균열과 같은 파손이 발생된다. 이는 고장이나 임무수명을 단축시키는 치명적인 원인이 된다. 따라서 랜덤환경에 노출된 PCB 설계를 위해 다양한 피로수명 예측이론이 제안되었으나 각기 다른 가정과 접근법으로 피로수명 예측 결과가 상이한 경우가 존재한다. 본 연구에서는 이러한 랜덤환경에 노출된 PCB를 위한 다양한 피로수명 예측식을 분석하고 피로수명 예측 결과를 시험 결과와 비교분석을 하여 장단점을 파악한다. Several electronic equipment mounted on high-tech vehicles such as automobiles, aircraft, satellites, and launch vehicles comprise numerous printed circuit boards (PCBs) that are subjected to random vibrations, which are the fatal cause of life-shortening. Accordingly, various fatigue life prediction theories have been proposed, but the results of fatigue life predictions are often different because of different assumptions and approaches used. This study analyzes various fatigue life prediction methods of the PCBs and compares the fatigue life prediction results through numerical examples referring to the test results.