• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.459-469
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• 2017

An air-to-ground guidance missile aimed to hit a main battle tank(MBT) should detect a ground moving target and estimate the target position to guide. In this paper, we detect a front ground moving target by using FMCW(Frequency Modulated Continuous Wave) and estimate the position by forward-looking SAR(Synthetic Aperture Radar) via scanning certain front ground section by steering a beam with narrow beamwidth left to right mechanically. Also, by MLE(Maximum Likelihood Estimation), degree of how fast the target approach or recede from the radar can be figured out from the estimated radial velocity of the moving target. Subsequently, we generate a radar image via corrected matched filter from phase history including the radial velocity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.202-209
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• 2014

In this paper, a developed device for detecting target's location and avoiding collision is proposed. Velocity and acceleration model of target are derived to estimate target's information, i.e. position, velocity and acceleration considering process and measurement noise. Kalman filtering method applied to the estimation process and its results was confirmed by simulation. The distance measurements system using laser sensor for moving target system is also developed to confirm the effectiveness of the proposed scheme. Experiments to get information of moving target with velocity and acceleration model was executed. The data with filtering and without filtering was compared by experiments. Discontinuous measured data was changed to smooth and continuous data by Kalman filtering. It is confirmed that desired data was obtained by applying proposed scheme. UI for measuring and monitoring the target data is developed and visual and auditory alarm function is attached on the system Finally, position estimation system of moving target with good performance is achieved by low price equipments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2707-2712
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• 2003

In this paper, with the utilization of a three-dimensional version of Leibniz’s rule, the procedure of deriving the time rate of change of an energy functional for axially moving continua is investigated. It will be shown that the method in [14], which describes the way of getting the time rate of change of an energy functional in Eulerian description, and subsequent results in [10, 11] are not complete. The key point is that the time derivatives at boundaries in the Eulerian description of axially moving continua should take into account the velocity of the moving material itself. A noble way of deriving the time rate of change of the energy functional is proposed. The correctness of the proposed method has been confirmed by other approaches. Two examples, one-dimensional axially moving string and beam equations, are provided for the purpose of demonstration. The results following the procedure proposed and the results in [14] are compared.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1815-1823
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• 2003

The vibrational system of this study consists of a cantilever pipe conveying fluid, the moving masses upon it and having an attached tip mass. The equation of motion is derived by using Lagrange's equation. The influences of the velocity and the inertia force of the moving mass and the velocities of fluid flow in the pipe have been studied on the dynamic behavior and the natural frequency of a cantilever pipe by numerical method. The deflection of the cantilever pipe conveying fluid is increased due to the tip mass and rotary Inertia. After the moving mass passed upon the cantilever pipe, the amplitude of pipe is influenced by energy variation when the moving mass fall from the cantilever pipe. As the moving mass increase, the frequency of the cantilever pipe conveying fluid is increased. The rotary inertia of the tip mass influences much on the higher frequencies and vibration mode.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.515-526
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• 2017

Dynamic response of functionally graded Carbon nanotubes (FG-CNT) reinforced pipes conveying viscous fluid under accelerated moving load is presented. The mixture rule is used for obtaining the material properties of nano-composite pipe. The radial force induced by viscous fluid is calculated by Navier-Stokes equation. The material properties of pipe are considered temperature-dependent. The structure is simulated by Reddy higher-order shear deformation shell theory and the corresponding motion equations are derived by Hamilton's principal. Differential quadrature (DQ) method and the Integral Quadrature (IQ) are applied for analogizing the motion equations and then the Newmark time integration scheme is used for obtaining the dynamic response of structure. The effects of different parameters such as boundary conditions, geometrical parameters, velocity and acceleration of moving load, CNT volume percent and distribution type are shown on the dynamic response of pipe. Results indicate that increasing CNTs leads to decrease in transient deflection of structure. In accelerated motion of the moving load, the maximum displacement is occurred later with respect to decelerated motion of moving load.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.139-148
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• 2016

The passive control methods such as horizontal and vertical fences on the lower surface of the bluff body were applied to suppress the vortex shedding and enhance the aerodynamic stability of flow. For investigating the effects of the passive control methods, wind tunnel experiments on the unsteady flow field around a bluff body near a moving ground were performed. The boundary layer and velocity profiles were measured by the Hot Wire Anemometer (HWA) system and the vortex shedding patterns and flow structures in a wake region were visualized via the Particle Image Velocimetry (PIV) system. Also, it is a measuring on moving ground condition that the experimental values of the critical gap distances, Strouhal numbers and aerodynamic force FFT analyses. Through the experiments, we found that the momentum supply due to moving ground caused the vortex shedding at the lower critical gap distance rather than that of fixed ground. The horizontal and vertical fences increase the critical gap distance and it can suppress the vortex shedding. Consequently, the stability characteristics of the bluff body near a moving ground could be effectively enhanced by the simple passive control such as the vertical fences.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.11
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• pp.19-27
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• 1998

To achieve the required services in the next-generation cellular telephone systems, the size of the cell become smaller and/or is of mixed macrocells and microcells. For more efficient system control, We make use of the mobile position and velocity information, provided that the mobility information is relatively accurate. In this paper, we propose an improved version of path-loss measurement algorithm introduced in literature[11]. The microcellular structure with severe multipath fading, reflection and refraction make mobile position and velocity estimation very difficult. In the proposed method, the pre-recorded path-loss informations, called the discrete position data base, are searched to estimate the position. Velocity estimation is obtained as a difference of the position values with respect to the time difference. Moving average filter is applied to smooth the estimated velocity and to reduce the error in the estimates. We also propose a method to simplify system implementation by reducing search area for discrete area database.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.215-226
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• 2007

To verify the performance of roadside barriers, occupant risk indices are calculated from acceleration and angular velocity data of vehicle crash tests. The occupant risk indices to be computed include THIV(Theoretical Head Impact Velocity), PHD(Post-impact Head Deceleration), ASI(Acceleration Severity Index), OIV(Occupant Impact Velocity) and ORA(Occupant Ridedown Acceleration). There is a confusion due to different values of occupant risk indices produced for the same test data because various computational procedures and data processing methods can be applied to compute them. To slove this problem the effects of various numerical procedures and data processing methods on occupant risk indices were investigated. If the sampling rate specified in the guidelines is used for full-scale vehicle crash tests, an interpolation of impact time and numerical integration methods do not result in an appreciable change of THIV and OIV. The way to determine 10msec moving average for PHD and zero offset of data processing should be specified in the guidelines because 10msec moving average and zero offset methods have a significant influence on occupant risk indices.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.3
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• pp.170-184
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• 2024

With the advancement of autonomous navigation technology in maritime domain, there is an active research on swarming Unmanned Surface Vehicles (USVs) that can fulfill missions with low cost and high efficiency. In this study, we propose a formation control algorithm that maintains a certain shape when multiple unmanned surface vehicles operate in a swarm. In the case of swarming, individual USVs need to be able to accurately follow the target state and avoid collisions with obstacles or other vessels in the swarm. In order to generate guidance commands for swarm formation control, the potential field method has been a major focus of swarm control research, but the method using the potential field only uses the position information of obstacles or other ships, so it cannot effectively respond to moving targets and obstacles. In situations such as the formation change of a swarm of ships, the formation control is performed in a dense environment, so the position and velocity information of the target and nearby obstacles must be considered to effectively change the formation. In order to overcome these limitations, this paper applies a method that considers relative velocity to the potential field-based guidance law to improve target following and collision avoidance performance. Considering the relative velocity of the moving target, the potential field for nearby obstacles is newly defined by utilizing the concept of Velocity Obstacle (VO), and the effectiveness and efficiency of the proposed method is verified through swarm control simulation, and swarm control experiments using a small scaled unmanned surface vehicle platform.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.1-8
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• 2020

This paper studied a method of estimating target information using a radar in wireless communication. Position information on the target can be estimated angle, distance and velocity. The velocity information can be estimated since the Doppler frequency is changed in the moving target. The signal incident on the receiving array antenna is multiplied by the delay time and the reference signal to represent the output signal. This output signal is estimated by applying FFT (Fast Fourier Transform) after calculating signal correlation through correlation integrator. Since the output signal must be calculated within the correlator, it should be processed with the Dwell time. The correlation signal of the correlation integrator outside this Dwell time is indicated by the velocity measurement error. The FFT is applied to the signal that has passed through the correlated integrator in order to estimate the distance of the signal. The Doppler resolution must be improved because the FFT estimates target information using the Doppler information. The Doppler resolution decreases with increasing the integration time. The velocity information estimation should have no spread of the velocity. As a result of the simulation, there was no spread of the target velocity in this study.