• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.141-144
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• 2002

This paper describes a new feature based tracking system that can track moving objects with a pan-tilt camera. We extract corner features of the scene and tracks the features using filtering, The global motion energy caused by camera movement is eliminated by finding the maximal matching position between consecutive frames using Pyramidal template matching. The region of moving object is segmented by clustering the motion trajectories and command the pan-tilt controller to follow the object such that the object will always lie at the center of the camera. The proposed system has demonstrated good performance for several video sequences.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.743-748
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• 2008

This paper presents an inertia type of piezostack based active mount for unmanned aero vehicle (UAV) camera system. After identifying the stiffness and damping properties of the rubber element and piezostack a mechanical model of the active mount system is established. The governing equation of mount is them derived and expressed in a state space farm. Subsequently, a sliding mode controller which is robust to uncertain parameters is designed in order to reduce the vibration imposed according to the military specification associated with UAV camera mount system operation. Control performances such as acceleration and transmitted force are evaluated through both computer simulation and experimental implementation.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.144-151
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• 2004

In this paper, we propose an active stereo surveillance system with human-like convergence function. The proposed system uses a bottom-up saliency map model with the human-like selective attention visual function to select an interesting region in each camera. and this system compares the landmarks whether the selective region in each camera finds a same region. If the left and right cameras successfully find a same landmarks, the implemented vision system focuses on the landmark. Using the motor encoder information, we can automatically obtain the depth information and resultantly construct a depth map using the depth information. Computer simulation and experimental results show that the proposed convergence method is very effective to implement the active stereo surveillance system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1278-1285
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• 2008

This paper presents an inertia type of piezostack based active mount fur unmanned aero vehicle (UAV) camera system. After identifying the stiffness and damping properties of the rubber element and piezostack a mechanical model of the active mount system is established. The governing equation of mount is then derived and expressed in a state space form. Subsequently, a sliding mode controller which is robust to uncertain parameters is designed in order to reduce the vibration imposed according to the military specification associated with UAV camera mount system operation. Control performances such as acceleration and transmitted force are evaluated through both computer simulation and experimental implementation.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.1106-1109
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• 2012

The stability of object tracking in non-stationary camera environment, such as intelligent surveillance system using a pan/tilt camera, is less stable compared with stationary camera environment. This is due to the fact that it is difficult to model a background image in non-stationary environment. In this letter, we propose a non-stationay pan/tilt camera surveillance system which uses a stop/go procedure together with a real-time active contour. The proposed system can track the object stable even in an environment where only a few difference frames can be obtained.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.6
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• pp.1166-1191
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• 2011

This paper presents an adaptive active tracking system with sector based scanning for a single PTZ camera. Dividing sectors on an image reduces the search space to shorten selection time so that the system can cover many targets. Upon the selection of a target, the system estimates the target trajectory to predict the zooming location with a finite amount of time for camera movement. Advanced estimation techniques using probabilistic reason suffer from the unknown object dynamics and the inaccurate estimation compromises the zooming level to prevent tracking failure. The proposed system uses the simple piecewise estimation with a few frames to cope with fast moving objects and/or slow camera movements. The target is tracked in multiple steps and the zooming time for each step is determined by maximizing the zooming level within the expected variation of object velocity and detection. The number of zooming steps is adaptively determined according to target speed. In addition, the iterative estimation of a zooming location with camera movement time compensates for the target prediction error due to the difference between speeds of a target and a camera. The effectiveness of the proposed method is validated by simulations and real time experiments.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.27-35
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• 2004

In the field of machine vision using a single camera mounted on a mobile robot, although the detection and tracking of moving objects from a moving observer, is complex and computationally demanding task. In this paper, we propose a new scheme for a mobile robot to track and capture a moving object using images of a camera. The system consists of the following modules: data acquisition, feature extraction and visual tracking, and trajectory generation. And a single camera is used as visual sensors to capture image sequences of a moving object. The moving object is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the active camera. Uncertainties in the position estimation caused by the point-object assumption are compensated using the Kalman filter. To generate the shortest time trajectory to capture the moving object, the linear and angular velocities are estimated and utilized. The experimental results of tracking and capturing of the target object with the mobile robot are presented.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2361-2369
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• 2020

Compton cameras using large scintillators have been developed for high imaging sensitivity. These scintillator-based Compton cameras, however, mainly due to relatively low energy resolution, suffer from undesired background-radiation signals, especially when radioactive materials' activity is very low or their location is far from the Compton camera. To alleviate this problem for a large-size Compton camera, in the present study, a hybrid-type shielding system was designed that combines an active shield with a veto detector and a passive shield that surrounds the active shield. Then, the performance of the hybrid shielding system was predicted, by Monte Carlo radiation transport simulation using Geant4, in terms of minimum detectable activity (MDA), signal-to-noise ratio (SNR), and image resolution. Our simulation results show that, for the most cases, the hybrid shielding system significantly improves the performance of the large-size Compton camera. For the cases investigated in the present study, the use of the shielding system decreased the MDA by about 1.4, 1.6, and 1.3 times, increased the SNR by 1.2-1.9, 1.1-1.7, and 1.3-2.1 times, and improved the image resolution (i.e., reduced the FWHM) by 7-8, 1-6, and 3-5% for ¹³⁷Cs, ⁶⁰Co, and ¹³¹I point source located at 1-5 m from the imaging system, respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.767-773
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• 2010

In the present work, vibration control performance of piezoactuator-based active mount system for unmanned aero vehicle(UAV) equipment is evaluated via hardware in the loop simulation(HILS). At first, the vibration level of UAV is measured and from this vibration data, the proper piezostack actuator is selected. Then, the dynamic model of active mount system including four active mounts and UAV camera equipment is derived. In order to evaluate vibration control performance, the HILS system is constructed. The proposed mount is prepared as hardware part and the other mounts are considered in software part. A sliding mode controller is designed and implemented to the HILS system. Effective vibration control results are presented in both time and frequency domains.

• International Journal of Control, Automation, and Systems
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• v.3 no.3
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• pp.444-452
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• 2005

A new scheme for a mobile robot to track and capture a moving object using camera images is proposed. The moving object is assumed to be a point-object and is projected onto an image plane to form a geometrical constraint equation that provides the position data of the object based on the kinematics of the active camera. Uncertainties in position estimation caused by the point-object assumption are compensated for using the Kalman filter. To generate the shortest time path to capture the moving object, the linear and angular velocities are estimated and utilized. In this paper, the experimental results of the tracking and capturing of a target object with the mobile robot are presented.