• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.810-820
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• 2014

Recently many studies of Radar systems mounted on ground vehicles for autonomous driving, SLAM (Simultaneous localization and mapping) and collision avoidance are reported. In near field, several hits per an object are generated after signal processing of Radar data. Hence, clustering is an essential technique to estimate their shapes and positions precisely. This paper proposes a method of grouping hits in range-doppler domains into clusters which represent each object, according to the pre-defined rules. The rules are based on the perceptual cues to separate hits by object. The morphological connectedness between hits and the characteristics of SNR distribution of hits are adopted as the perceptual cues for clustering. In various simulations for the performance assessment, the proposed method yielded more effective performance than other techniques.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.10
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• pp.104-110
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• 2005

In this paper, unmanned vehicle system and VFF algorithm development with vehicle dynamics is the main topic as a part of Intelligent Transportation System. Unmanned vehicle system is classified by vehicle system and control system. Authors used RC servo motor for longitudinal control via throttle angle, shift lever control, and brake control. For lateral control, authors used step motor, equipped with reduction gear. Unmanned vehicle has nine ultrasonic sensors in front of the unmanned vehicle. After the microcontroller computes the distance between unmanned vehicle and obstacle, the control computer calculates the steering angle enough to avoid the obstacle.

• ETRI Journal
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• v.40 no.4
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• pp.511-521
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• 2018

The ability to realize human-motion imitation using robots is closely related to developments in the field of artificial intelligence. However, it is not easy to imitate human motions entirely owing to the physical differences between the human body and robots. In this paper, we propose a work chain-based inverse kinematics to enable a robot to imitate the human motion of upper limbs in real time. Two work chains are built on each arm to ensure that there is motion similarity, such as the end effector trajectory and the joint-angle configuration. In addition, a two-phase filter is used to remove the interference and noise, together with a self-collision avoidance scheme to maintain the stability of the robot during the imitation. Experimental results verify the effectiveness of our solution on the humanoid robot Nao-H25 in terms of accuracy and real-time performance.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.4
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• pp.480-485
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• 2010

In this paper, we developed mobile robot platform called Ecobot for the application system of friendly environment smart home appliance. Ecobot fulfills the purposes of monitoring of the healthy environment and guidance in the application system of friendly smart environment home appliance, home network formed by Zigbee network. For the healthy environment, the system contains monitoring sensor. Moreover, it continuously keeps the healthy environment by controlling the smart home appliances linkng with Zigbee network. And also using the URG-04LX laser distance sensor, it monitors indoor environment through autonomous moving and collision avoidance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.111-118
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• 2006

It is indispensable to grasp the turning ability of a ship to operate her effectively. For this purpose, the author measured the turning ability of training ship, A-RA by use of bow thruster and stem rudder. The turning ability of this ship, in case of using both of stem rudder and bow thruster at the same time, caused by increase of steering angle provides more influence to the size of tactical diameter than it caused by the power of bow thruster. But the influence of bow thruster on the turning ability is available only within rudder angle $5^{\circ}\;-\;10^{\circ}$, so it is possible to grasp that the effect of bow truster is reduced as rudder angle become bigger. In case of the influence of bow thruster by her speed, the ability of bow thruster is very effective at low speed, but it is almost not available in normal turning speed. Therefore, the using both of stem rudder and bow thruster can be useful in case of low speed proceeding at entrance or departure of the narrow waterway or inside port which sea traffic is congest for collision avoidance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.769-771
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• 2011

The satellite payloaded on the 2nd stage of KSLV-I is planned to perform CCAM(Contamination and Collision Avoidance Maneuver) not to collide with KM(Kick Motor). At the moment, the satellite should pass through low density environment not to be contaminated by KM plume due to residual thrust. Therefore, it is necessary to predict the flow field of KM plume by residual thrust. In this paper, DSMC (Direct Simulation Monte-Carlo) method, which is widely accepted to simulate in rarefied regime, is used to compute the density field of KM plume by residual thrust and the result of DSMC simulation was compared with that of FLUENT to validate it.

• ETRI Journal
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• v.34 no.1
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• pp.24-34
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• 2012

In this paper, the directional carrier sense multiple access/collision avoidance (CSMA/CA) protocol in the immediate acknowledgement mode for IEEE 802.15.3c is analyzed under saturation environments. For the analysis, a sensing region and an exclusive region with a directional antenna are computed probabilistically and a Markov chain model in which the features of IEEE 802.15.3c and the effects of using directional antennas are incorporated is analyzed. An algorithm to find the maximal number of concurrently transmittable frames is proposed. The system throughput and the average transmission delay are obtained in closed forms. The numerical results show the impact of directional antennas on the CSMA/CA media access control (MAC) protocol. For instance, the throughput with a small beamwidth of antenna is more than ten times larger than that for an omnidirectional antenna. The overall analysis is verified by a simulation. The obtained results will be helpful in developing an MAC protocol for enhancing the performance of mmWave wireless personal area networks.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1054-1059
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• 2005

The artificial potential method uses a potential field to guide a robot from a start to a goal configuration respectively. The potential field consists of attractive potential used to pull a robot toward a goal and repulsive potential to keep it away from obstacles. However, there are two problems concerning local minimum and computational cost to be resolved in conventional artificial potential methods. This study proposes a method utilizing a spline surface that interpolates arbitrary boundaries and a domain reduction method that reduces the unnecessary area. The proposed spline surface interpolates arbitrary shaped boundaries and is used as an artificial potential to guide a robot for global motion planning of a mobile robot. A reduced domain process reduces the unnecessary domain. We apply a distance-weighted function as such a function, which blends distances from each boundary with a reduction in computational time compared with other analytical methods. As a result, this paper shows that an arbitrary boundary spline surface provides global planning and a domain reduction method reduces local minimum with quick operation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.595-604
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• 2016

Utilizing a standard 130-nm CMOS process, a RF frontend is designed at 24 GHz for automotive collision avoidance radar application. Single IF direct conversion receiver (DCR) architecture is adopted to achieve high integration level and to alleviate the DCR problem. The proposed frontend is composed of a two-stage LNA and downconversion mixers. To save power consumption, and to enhance gain and linearity, stacked NMOS-PMOS $g_m$-boosting technique is employed in the design of LNA as the first stage. The switch transistors in the mixing stage are biased in subthreshold region to achieve low power consumption. The single balanced mixer is designed in PMOS transistors and is also realized based on the well-known folded architecture to increase voltage headroom. This frontend circuit features enhancement in gain, linearity, and power dissipation. The proposed circuit showed a maximum conversion gain of 19.6 dB and noise figure of 3 dB at the operation frequency. It also showed input and output return losses of less than -10 dB within bandwidth. Furthermore, the port-to-port isolation illustrated excellent characteristic between two ports. This frontend showed the third-order input intercept point (IIP3) of 3 dBm for the whole circuit with power dissipation of 6.5 mW from a 1.5 V supply.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.2
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• pp.143-153
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• 2008

This paper describes the current research trend and future development direction of autonomous flight of the aircraft. The autonomous flight means that aircraft control system recognize and cope with the emergency situation confronted during the flight by itself. Current research for autonomous flight technology is mainly performed for the application to unmanned air vehicle. Considering advent of future air traffic management system and increasing demand of the unmanned air vehicle application, however, autonomous flight technology required to be combined with future air traffic management system. In this paper, the current air traffic management system and anticipating change in future air traffic management system was investigated and research activities of autonomous flight technology was described as well as future prospect.