• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.4
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• pp.441-450
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• 2016

Wireless multi-hop communication is one of the key technologies to operate Unmanned Ground System (UGS) networks efficiently. Conventionally a lot of routing protocol has been developed and studied for multi-hop networks like Mobile Ad-hoc Network (MANET). However, the routing protocol for the unique environment of the UGS requires further studies, since conventional routing protocols cannot be used itself for UGS networks. In this paper, we propose the Betweenness Centrality based Geographic Routing (BCGR) which considers the main function of UGS. BCGR utilizes expanded ego betweenness centrality, mobility and location information error, respectively. We have conducted a simulation study for evaluating the performance of the BCGR using ns-3, and our simulation results show that BCGR outperforms the conventional routing protocols such as AODV and GPSR in terms of end-to-end transmission reliability, throughput and delay.

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.5-8
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• 2002

In this paper, we propose the self-autonomous algorithm for mobile robot system. The proposed mobile robot system controlled by Personal Digital Assistant(PDA) can follow the target at regular intervals. The mobile robot can evaluate the distance between robot and target with ultrasonic sensors, transmits the distance to the PDA. The velocity and direction decided in PDA are transmitted to the mobile robot with wireless LAN communication. Considering the state, velocity-changing and distance-maintenance, of the mobile robot, driving velocity and direction are applied. For safety, the velocity of the mobile robot is changed step by step. As a result, we confirm the ability of following the target with proposed mobile robot.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.340-342
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• 2007

When a system is teleoperated in the indoor environment through the wireless LAN, the communication time delay that is due to the inherent characteristic and surrounding environment is random and unbounded. The time delay has a significant effect on the stability and performance of the teleoperating system. In this paper, we present the method that is the image compression, measuring time delay and switching control-mode corresponding to time delay automatically, to improve stability and performance, and the simple experiment is conducted to demonstrate the feasibility

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.509-512
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• 2002

We propose a control method for mobile robot system using the bluetooth. The control packet is defined and used for control of the mobile robot. The control packet is composed of behavior components and has reserved packets for future working. The control packet has to be simple and provide commands to the mobile robot, since the bluetooth has a limited bandwidth. The data transmission rate and the distance, which can control the mobile robot in various circumstances, for example, corridor, yard, and room are measured by some experiments.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.2
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• pp.105-113
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• 2007

Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of application. Sensor position is used for its data to be meaningful and for energy efficient data routing algorithm especially geographic routing. The previous works for sensor localization utilize global positioning system(GPS) or estimate unknown-location nodes position with help of some small reference nodes which know their position previously. However, the traditional localization techniques are not well suited in the senor network for the cost of sensors is too high. In this paper, we propose the sensor localization method with a mobile robot, which knows its position, moves through the sensing field along pre-scheduled path and gives position information to the unknown-location nodes through wireless channel to estimate their position. We suggest using the sensor position estimation method and an efficient mobility path model. To validate our method, we carried out a computer simulation, and observed that our technique achieved sensor localization more accurately and efficiently than the conventional one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.937-941
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• 2016

This paper proposed an efficient multiple TCP mechanism using Android smartphones for remote control video Wi-Fi stream transmission via network communications in real time. The wireless video stream transmission mechanism can be applied in various area such as real time server stream transmissions, movable drones, disaster robotics and real time security monitoring systems. Moreover, we urgently need to transmit data in timely fashion such as medical emergency, security surveillance and disaster prevention. Our parallel TCP transmission system can play an important role in several area such as real time server stream transmissions, movable drones, disaster robotics and real time security monitoring systems as mentioned in the previous sentence. Therefore, we designed and implemented a parallel TCP transmission (parallel stream) for an efficient real time video streaming services. In conclusion, we evaluated proposed mechanism using parallel TCP transmission under various environments with performance analysis.