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Kim, Yunjoong,Kim, Mingu,Han, Bumku,Kim, Youdan,Shin, Hohyun The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.2
The optimum design of an SAR (Synthetic Aperture Radar) satellite constellation is developed herein using a genetic algorithm. The performance of Earth observations using a satellite constellation can be improved by minimizing the maximum revisit time. Classical orbit design using analytic methods has limitations when addressing orbit dynamics due to various disturbances. To overcome this issue, an optimization technique based on a genetic algorithm is used. STK (Systems Tool Kit) is utilized to propagate the satellite orbit when considering external disturbances, and the maximum revisit time on the earth observation area is calculated. By minimizing the performance index using a genetic algorithm, the optimum orbit of the satellite constellation is designed. Numerical results are provided to demonstrate the performance of the proposed method.
Lyapunov-based impact time control guidance laws against stationary targets
Mingu Kim,Bokyung Jung,Bumku Han,Sangchul Lee,Youdan Kim IEEE 2015 IEEE transactions on aerospace and electronic syst Vol.51 No.2
<P>Nonlinear guidance laws that consider impact time constraints are proposed. Two-dimensional and three-dimensional impact time control guidance laws are derived using Lyapunov stability theory. Under the consideration of the nonlinear kinematics, it is shown that the missile states converge to the desired equilibrium point by the Lyapunov stability theory. The singularity issue of the proposed guidance laws is also analyzed. Numerical simulations are performed to verify the performance of the proposed guidance laws.</P>
Fully Autonomous Vision-Based Net-Recovery Landing System for a Fixed-Wing UAV
Kim, H. Jin,Mingu Kim,Hyon Lim,Chulwoo Park,Seungho Yoon,Daewon Lee,Hyunjin Choi,Gyeongtaek Oh,Jongho Park,Youdan Kim IEEE 2013 IEEE/ASME transactions on mechatronics Vol.18 No.4
<P>This paper presents an autonomous vision-based netrecovery system for small fixed-wing unmanned aerial vehicles (UAVs). A fixed-wing UAV platform is constructed using various avionic sensors, and integrated with a flight control system and a vision system. The ground operation system consists of a vision station and ground control station that provide operation commands and monitor the UAV status. The vision algorithm to detect the recovery net and provide the bearing angle to the guidance algorithm is explained, along with the discussions on the techniques employed to improve the reliability of visual detection. The system identification process and controller are described, which enables to track given waypoints and to approach the detected net under the pursuit guidance law. Experimental results show the autonomous capabilities including take-off, waypoint following, and vision-based net recovery. The proposed technique can be an effective solution to recover fixed-wing UAVs without resorting to a complicated structure such as an instrumented landing system or expensive sensors such as a differential GPS.</P>
Kim, Mingu,Kim, Youdan The Korean Society for Aeronautical and Space Scie 2013 International Journal of Aeronautical and Space Sc Vol.14 No.1
Nonlinear guidance law combined with a pseudo pursuit guidance is proposed, to perform stationary target observation mission. Multiple UAVs are considered, with waypoint constraint. The whole guidance is divided into two steps: firstly, waypoint approach, with specified incidence angle; and secondly, loitering around the stationary target. Geometric approach is used to consider the constraint on the waypoint, and a specified phase angle between the loitering UAV and the approaching UAV. In the waypoint approach step, UAVs fly to the waypoint using the pseudo pursuit guidance law. After passing the waypoint, UAVs turn around the target, using a distance error dynamics-based guidance law. Numerical simulations are performed, to verify the performance of the proposed guidance law.
Kim, Dong-eun,Jung, Sunhee,Ryu, Hyung Won,Choi, Miri,Kang, Mingu,Kang, Hyunju,Yuk, Heung Joo,Jeong, Hyejeong,Baek, Jiyeon,Song, Jae-Hyoung,Kim, Janghwan,Kang, Hyojeung,Han, Sang-Bae,Oh, Sei-Ryang,Cho, Elsevier 2018 Journal of Functional Foods Vol.42 No.-
<P><B>Abstract</B></P> <P>Lytic induction of latent Epstein-Barr virus (EBV) has been considered as a therapeutic approach for efficient treatment of EBV-associated malignancies. Here, we established a robust assay system quantitatively measuring EBV lytic induction and identified three <I>Euphorbia</I> extracts as strong inducers from a screen of Korean medicinal plant extracts library. Expression of lytic genes were efficiently induced by each <I>Euphorbia</I> extract in SNU-719 (EBV-positive gastric carcinoma cells). <I>Euphorbia pekinensis</I>, out of three extracts, exhibited the most potent lytic-inducing activity. Importantly, treatment with <I>E. pekinensis</I> extract led to an obvious cytotoxic effect on SNU-719 cells, but little on MKN-74 cells (EBV-negative gastric carcinoma cells), indicating the selective oncolytic effect on EBV-positive gastric carcinoma. We further revealed that lytic-inducing activity of <I>E. pekinensis</I> was mediated by PKC/MEK signal. Moreover, we defined two structural analogs of PMA with strong lytic-inducing activity, suggesting their therapeutic applicability for the treatment of EBV-associated gastric carcinoma.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Identification of three <I>Euphorbia</I> extracts with EBV lytic-inducing activity. </LI> <LI> <I>Euphorbia</I> extracts efficiently induce lytic replication in most of cell population. </LI> <LI> <I>Euphorbia</I> extracts induce EBV reactivation through modulating PKC/MEK pathway. </LI> <LI> PMA analogs in <I>Euphorbia</I> extracts contribute to lytic induction of EBV. </LI> <LI> <I>E. pekinensis</I> extract has an oncolytic effect selectively on EBV-positive gastric carcinoma cells. </LI> </UL> </P>