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On the Modeling of Dynamic Systems
Suk, Jinyoung,Kim, Youdan The Korean Society for Aeronautical and Space Scie 2001 International Journal of Aeronautical and Space Sc Vol. No.
In this paper, several dynamic systems are modeled using the time domain finite element method. Galerkins' Weak Principle is used to model the general second-order mechanical system, and is applied to a simple pendulum dynamics. Problems caused by approximating the final momentum are also investigated. Extending the research, some dynamic analysis methods are suggested for the hybrid coordinate systems that have both slew and flexible modes. The proposed methods are based on both Extended Hamilton's Principle and Galerkin's Weak Principle. The matrix wave equation is propagated in space domain, satisfying the geometric/natural boundary conditions. As a result, the flexible motion can be obtained compatible with the applied control input. Numerical example is shown to demonstrate the effectiveness of the proposed modeling methods for the hybrid coordinate systems.
Jinyoung Suk,Youngsaeng Lee,Seungjoo Kim 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.5
This paper presents a consequence of the systematic approach to identify the aerodynamic parameters of an unmanned aerial vehicle (UA V) equipped with the automatic flight control system. A 3-2-1-1 excitation is applied for the longitudinal mode while a multi-step input is applied for lateral/directional excitation. Optimal time step for excitation is sought to provide the broad input bandwidth. A fully automated programmed flight test method provides highquality flight data for system identification using the flight control computer with longitudinal and lateral/directional autopilots, which enable the separation of each motion during the flight test. The accuracy of the longitudinal system identification is improved by an additional use of the closed-loop flight test data. A constrained optimization scheme is applied to estimate the aerodynamic coefficients that best describe the time response of the vehicle. An appropriate weighting function is introduced to balance the flight modes. As a result, concurrent system models are obtained for a wide envelope of both longitudinal and lateral/directional flight maneuvers while maintaining the physical meanings of each parameter.
Ground Test and Evaluation of a Flight Control System for Unmanned Aerial Vehicles
Jinyoung Suk,Jinhyung Kim 한국항공우주학회 2004 International Journal of Aeronautical and Space Sc Vol.5 No.1
UAV(Unmanned Aerial Vehicle) has become one of the most popular military/commercial aerial robots in the new millennium. In spite of all the advantages that UAVs inherently have, it is not an easy job to develop a UAV because it requires very systematic and complete approaches in full development envelop. The ground test and evaluation phase has the utmost importance in the sense that a well-developed system can be best verified on the ground. In addition, many of the aircraft crashes in the flight tests were resulted from the incomplete development procedure. In this research, a verification procedure of the whole airborne integrated system was conducted including the flight management system. An airborne flight control computer(FCC) senses the external environment from the peripheral devices and sends the control signal to the actuating system using the assigned control logic and flight test strategy. A ground test station controls the mission during the test while the downlink data are transferred from the flight management computer using the serial communication interface. The pilot control box also applies additional manual actuating commands. The whole system was tested/verified on the wind-tunnel system, which gave a good pitch control performance with a pre-specified flight test procedure. The ground test system guarantees the performance of fundamental functions of airborne electronic system for the future flight tests.
시간유한요소법을 이용한 분포형 구동기의 형상최적화에 관한 연구
석진영(Jinyoung Suk),김유단(Youdan Kim) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.9
시간유한요소법은 시간영역을 고정시키고 행렬 미분방정식 형태의 공간전파 관계식을 풂으로써 시간과 공간에 대한 동적 해석을 수행하는 방법이다. 이 방법은 공간이산화 유한요소법이나 시/공간 동시이산화 유한요소법에 비해 공간에 관한 자유도가 발생하는 것 이 두드러진 특징으로, 이를 이용하여 분포형 구동기의 공간에 따른 특성을 최적화하는 데에 효율적으로 사용될 수 있다. 본 논문에서는 임의의 초기조건을 반영할 수 있도록 구성된 상태변수 벡터를 이용하여 구조물을 시간영역에서 이산화하고, 공간영역에서 전파관계식 및 경계조건을 이용하여 공간전파 관계식을 형성하였다. 이 때 구동기의 공간에 따른 형상 분포는 설계되어야 할 변수의 함수이고, 시간반응은 형상함수를 이용하여 이산화 하였다. 포텐셜 에너지 및 운동에너지를 구조물의 변위제어에 적절한 최적의 성능지수로 설정하고, 이를 최소화하도록 미지의 함수인 구동기의 분포형상을 구하였다. 일반적으로 구조물은 임의의 초기조건에서 외란을 받게 되나, 본 연구에서는 구현가능한 제어법칙을 이용하여 최종시간에서 안정화(rest) 조건을 만족한다고 가정하였다. 구동기 분포형상 최적화를 위해 상태/준상태 방정식을 유도하였다. 서브행렬 재형상화와 시/공간 경계조건을 통해 상태변수와 준상태변수에 대한 Ricatti 미분방정식을 유도하였다. 이를 통해 구동기 분포형상 최적화를 구현하였으며, 수치 시뮬레이션을 통해 적절한 구동기의 분포형상 최적화를 수행할 수 있음을 보였다. A dynamic analysis method that freezes a time domain by discretization and solves the spatial propagation equation has a unique feature that provides a degree of freedom on spatial domain compared with the space discretization or space-time discretization finite element method. Using this feature, the time finite element analysis can be effectively applied to optimize the spatial characteristics of distributed type actuators. In this research, the time domain finite element method was used to discretize the model. A state variable vector was used in the discretization to include arbitrary initial conditions. A performance index was proposed on spatial domain to consider both potential and vibrational energy, so that the resulting shape of the distributed actuator was optimized for dynamic control of the structure. It is assumed that the structure satisfies the final rest condition using the realizable control scheme although the initial disturbance can affect the system response. Both equations on states and costates were derived based on the selected performance index and structural model. Ricatti matrix differential equations on state and costate variables were derived by the reconfiguration of the sub-matrices and application of time/space boundary conditions, and finally optimal actuator distribution was obtained. Numerical simulation results validated the proposed actuator shape optimization scheme.
Analysis of photovoltaic potential at abandoned mine promotion districts in Korea
Jinyoung Song,최요순,Suk-Ho Yoon 한국자원공학회 2015 Geosystem engineering Vol.18 No.3
The present study analyzed the photovoltaic (PV) potentials at seven abandoned mine promotion districts in Korea: Taebaek, Samcheok, Jeongseon, Yeongwol, Mungyeong, Hwasun, and Boryeong. A PV system with a capacity of 99 kW was considered at each abandoned mine promotion district. The estimated electric power productions and economic effects of PV systems were analyzed using RETScreen software developed by Natural Resources Canada (NRC). The results showed that the Boryeong district has the highest PV potential, with estimated electric power production of about 83.43 MWh/year, which means a present net value of 69.2 million KRW and a payback period of about 13 years.