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박찬덕 ( Park Chan Deok ),박병수 ( Park Byung Soo ) 한국구조물진단유지관리공학회 2018 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.22 No.1
This study is a case of construction after bridge demolition due to the aging of bridges operating the railway. Due to the influence of the pier vibration on the railway, the influence of the railway line, the construction period, etc., the P.B.S technique was applied to the coping pile foundation. It was completed in 5 days per 1 bridge pier by the PBS method. Since it is constructed in the dry season (from October to April) without vibration and noise, it can be installed safely on the rail rail of the pier of the bridge .
김경하,박찬덕,박상영 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.4
This work presents fuel-optimal altitude maintenance of Low-Earth-Orbit (LEO) spacecrafts experiencing non-negligible air drag and J2 perturbation. A pseudospectral (direct) method is first applied to roughly estimate an optimal fuel consumption strategy, which is employed as an initial guess to precisely determine itself. Based on the physical specifications of KOrea Multi-Purpose SATellite-2 (KOMPSAT-2), a Korean artificial satellite, numerical simulations show that a satellite ascends with full thrust at the early stage of the maneuver period and then descends with null thrust. While the thrust profile is presumably bang-off, it is difficult to precisely determine the switching time by using a pseudospectral method only. This is expected, since the optimal switching epoch does not coincide with one of the collocation points prescribed by the pseudospectral method, in general. As an attempt to precisely determine the switching time and the associated optimal thrust history, a shooting (indirect) method is then employed with the initial guess being obtained through the pseudospectral method. This hybrid process allows the determination of the optimal fuel consumption for LEO spacecrafts and their thrust profiles efficiently and precisely.
황인영,박찬덕,박상영 한국우주과학회 2013 Journal of Astronomy and Space Sciences Vol.30 No.1
A collision-free formation reconfiguration trajectory subject to the linearized Hill’s dynamics of relative motion is analytically developed by extending an algorithm for gravity-free space. Based on the initial solution without collision avoidance constraints, the final solution to minimize the designated performance index and avoid collision is found, based on a gradient method. Simple simulations confirm that satellites reconfigure their positions along the safe trajectories, while trying to spend minimum energies. The algorithm is applicable to wide range of formation flying under the Hill’s dynamics.
Performance Analysis of Generating Function Approach for Optimal Reconfiguration of Formation Flying
이광원,박상영,박찬덕 한국우주과학회 2013 Journal of Astronomy and Space Sciences Vol.30 No.1
The use of generating functions for solving optimal rendezvous problems has an advantage in the sense that it does not require one to guess and iterate the initial costate. This paper presents how to apply generating functions to analyze spacecraft optimal reconfiguration between projected circular orbits. The series-based solution obtained by using generating functions demonstrates excellent convergence and approximation to the nonlinear reference solution obtained from a numerical shooting method. These favorable properties are expected to hold for analyzing optimal formation reconfiguration under perturbations and non-circular reference orbits.