• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2937-2943
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• 2013

This paper introduces a real-time flocking simulation framework through radial basis function(RBF). The proposed framework first divides the entire environment into a grid structure and then assign a vector per each cell. These vectors are automatically calculated by using RBF function, which is parameterized from user-input control lines. Once the construction of vector field is done, then, flocks determine their path by following the vector field flow. The collision with static obstacles are modeled as a repulsive vector field, which is ultimately over-layed on the existing vector field and the inter-individual collision is also handled through fast lattice-bin method.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.145-151
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• 2006

In this paper, we propose a novel navigation method combined Nearness Diagram, Limit-Cycle method and the Vector Field Method for avoidance of unexpected obstacles in the dynamic environment. The Limit-Cycle method is used to obstacle avoidance in front of the robot and the Vector Field Method is used to obstacle avoidance in the side of robot. And the Nearness Diagram Navigation is used to obstacle avoidance in the nearness area of the robot. The performance of the proposed method is demonstrate by simulations.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.599-602
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• 2007

Generally, the mobile robot navigation with obstacle avoidance is one of the key issues to be looked into for successful applications of autonomous mobile robots. In this paper, the Univector field based method is proposed for mobile robot to accomplish the obstacle avoidance and the robot orientation at the target position. Univector field method guarantees the desired posture of the robot at the target position. But it is not effective Univector to avoid obstacles. To solve this problem, modified univector field is used. With this proposed method, robot navigation task becomes easier and effectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.535-542
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• 2011

The Global Navigation Satellite System(GNSS) is being utilized in numerous applications. The research for autonomous guided vehicles(AGVs) using precise positioning of GNSS is in progress. GNSS based AGVs is useful for setting driving path. This AGV system is more efficient than the previous one. Escipecially, the obstacle is positioned the driving path. Previcious AGVs which follow marker or wires laid out on the road have to stop the front of obstacle. But GNSS based AGVS can continuously drive using obstacle avoidance. In this paper, we developed collision avoidance system for GNSS based AGV using laser scanner and collision avoidance path setting algorithm. And we analyzed the developed system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1173-1179
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• 2012

In this paper, collision avoidance beamforming(CA-BF) technology is proposed to mitigate inter-cell interference in cooperative wireless communications system with limited feedback. Each acess terminal(AT) selects both the best BF weight vector for a serving base transceiver station(BTS) and the most interfering BF weight vectors of interfering BTSs within a cluster, and sends it back to a cluster scheduler. At the cluster scheduler, a set of transmit BF weights of BTSs and the corresponding scheduled ATs are jointly determined to avoid collision among beams formed by BTSs within a cluster, which enhances system throughput by mitigating inter-cell interference. It is shown that the proposed CA-BF outperforms existing non-coordinated BF schemes in terms of the average system throughput.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.49-53
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• 2018

Parabolic offset antenna is widely used for wireless communication system. The general structure of parabolic offset antenna system is composed of supporting stand and RF devices under parabolic reflector. However sidelobe distortion in gain pattern is occurred by supporting stand and RF devices. Depending on position of subsidiary devices, angle of sidelobe distortion can be changed. In this paper we describe method for sidelobe distortion suppression using raytracing. We calculate 3D vector for sidelobe distortion suppression zone by raytracing method and compare when subsidiary device is in sidelobe distortion suppression zone or not. By comparison, we show method for parabolic antenna sidelobe distortion suppression.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.351-357
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• 2011

Rotor position is essentially required for vector control of permanent magnet synchronous generator(PMSG) and position sensor such as encoder are generally used for the purpose of position sensing. However, the use of position sensor degrades reliability of PMSG control system. This paper presents position sensor fault tolerant control method for PMSG control system. Sensorless position estimator based on extended electromotive force(EMF) is operated in parallel with sensored vector control to provide rapid reconfiguration capability to sensorless vector control at the moment of position sensor fault detection. Experimental results show the effectiveness of the proposed method.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.623-629
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• 2018

In this paper, we propose a real-time obstacle detection and avoidance path generation algorithm for UAV. 2-D Lidar is used to detect obstacles, and the detected obstacle data is used to generate real-time histogram for local avoidance path and a 2-D SLAM map used for global avoidance path generation to the target point. The VFH algorithm for local avoidance path generation generates a real-time histogram of how much the obstacles are distributed in the vector direction and distance, and this histogram is used to generate the local avoidance path when detecting near fixed or dynamic obstacles. We propose an algorithm, called modified $RRT^*-Smart$, to overcome existing limitations. That generates global avoidance path to the target point by creating lower costs because nodes are checked whether or not straight path to a target point, and given arbitrary lengths and directionality to the target points when nodes are created. In this paper, we prove the efficient avoidance maneuvering through various simulation experiment environment by creating efficient avoidance paths.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.3
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• pp.67-75
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• 1998

This paper presents a new robot motion planning method for moving obstacle avoidance. To consider the mobility of a moving obstacle, we define virtual distance function(VDF) between the robot and the obstacle. At each sampling time, we use the VDF to construct an artificial potential, considering the motion of obstacles. The robot moves according to the repulsive and attractive force vector induced by the artificial potential function. The proposed algorithm can be driven the robot to avoid moving obstacles in real time. Some simulation studies show the effectiveness of the proposed method.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.6
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• pp.470-476
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• 2001

This paper presents a new algorithm of path planning and obstacle avoidance for autonomous mobile robots with vision system that is working in unknown environments. Distance variation technique is used in path planning to approach the target and avoid obstacles in work space as well . In this approach, the Sobel operator is employed to detect edges of obstacles and the distances between the mobile robot and the obstacles are measured. Fuzzy rules are used for trajectory planning and obstacle avoidance to improve the autonomy of mobile robots. It is shown by computer simulation that the proposed algorithm is superior to the vector field approach which sometimes traps the mobile robot into some local obstacles. An autonomous mobile robot with single vision is developed for experiments. We also show that the developed mobile robot with the proposed algorithm is navigating very well in complex unknown environments.