• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.88-93
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• 1998

This paper presents a new solution approach to moving obstacle avoidance problem for a mobile robot. A new concept avoidability measure(AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function(VDF) is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terns of the VDF, an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived form the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.

• Electronics and Telecommunications Trends
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• v.35 no.7
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• pp.13-22
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• 2020

There is no denying that computing power has been a crucial driving force behind the development of artificial intelligence today. In addition, artificial intelligence (AI) semiconductors and computing systems are perceived to have promising industrial value in the market along with rapid technological advances. Therefore, success in this field is also meaningful to the nation's growth and competitiveness. In this context, ETRI's AI strategy proposes implementation directions and tasks with the aim of strengthening the technological competitiveness of AI semiconductors and computing systems. The paper contains a brief background of ETRI's AI Strategy #2, research and development trends, and key tasks in four major areas: 1) AI processors, 2) AI computing systems, 3) neuromorphic computing, and 4) quantum computing.

• The Journal of Korea Robotics Society
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• v.16 no.1
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• pp.17-22
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• 2021

Soft robot research has been actively conducted due to the advantages of soft materials that have less motion restrictions and higher energy efficiency compared to rigid robots. In particular, soft robots are being applied in more and more diverse fields, and the need for soft robots is increasing, especially when dealing with soft or deformable objects that rigid robots cannot perform. Various soft robots are being developed, and studies on artificial muscles with versatility, seamless integration with sensing, and self-healing capabilities are being proposed. In this study, we propose one of the most simple rectangular shaped HASEL (Hydraulically amplified self-healing electrostatic) actuators and compare the performance according to shape deformation such as the size or ratio of actuators and electrodes. Developing these actuators can be used in many ways for artificial muscles in soft robotics.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.1
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• pp.33-38
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• 2024

In this paper, we propose the implementation of a drone delivery system using artificial intelligence in a situation where the use of drones is rapidly increasing and human errors are occurring. This system requires the implementation of an accurate control algorithm, assuming that last-mile delivery is delivered to the apartment veranda. To recognize the delivery location, a recognition system using the YOLO algorithm was implemented, and a delivery system was installed on the drone to measure the distance to the object and increase the delivery distance to ensure stable delivery even at long distances. As a result of the experiment, it was confirmed that the recognition system recognized the marker with a match rate of more than 60% at a distance of less than 10m while the drone hovered stably. In addition, the drone carrying a 500g package was able to withstand the torque applied as the rail lengthened, extending to 1.5m and then stably placing the package down on the veranda at the end of the rail.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.377-378
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• 2010

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.88-88
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• 2007

• The Korean Journal of Air & Space Law and Policy
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• v.15
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• pp.146-181
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• 2002

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.731-738
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• 2000

The purpose of this study was to investigate the change of 3 point bending properties of various nickel titanium wires after recycling. Four Types of nickel-titanium (Align: martensitic type, NiTi, Optimalloy, Sentalloy: austenitic type) wires were divided to three groups: as-received condition (T0: control group), treated in artificial saliva for four weeks (T1) and autoclaved after being treated in artificial saliva (T2). Detrimental changes were observed for the selected mechanical properties in three point bending test. Loading force at 3mm deflection, unloading force at 3mm deflection, stress hysteresis, loading force at 1mm deflection, unloading force at 1mm deflection and stress hysteresis at 1mm deflection were calculated. The findings suggest that : 1. Align demonstrated statistically significant increase In loading force (p<0.05) and unloading force (p<0.01) at 3mm deflection after recycling(T2), but NiTi, Optimalloy and Sentalloy showed no statistically difference after recycling. 2. Align demonstrated statistically significant decrease in hysteresis(p<0.01) after recycling(T2) but NiTi, Optimalloy and Sentalloy showed no statistically significant difference after recycling. 3. All wires showed no statistically significant difference in loading force at 1mm deflection after recycling(T2). 4. Align demonstrated statistically significant decrease in unloading force in 1mm deflection (p<0.05) after recycling(T2) but NiTi, Optimalloy and Sentalloy showed no statistically difference after recycling 5. Loading force and unloading force of T1 showed no significant change compared with those of T0, but loading force and unloading force of T2 showed significant changes compared with those of T0(p<0.05, p<0.01 respectively). 6. Align demonstrated a tendency to lose some of this pseudoelasticity in T1 and pseudoplasticity and pseudoelasticity in T2.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.1
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• pp.9-16
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• 2002

In this paper, we intend to demonstrate a new intuitive force-feedback device for advanced VR applications. Force feed-back for the device is tension based and is characterized by 7 degrees of freedom (DOF); 3 DOF for translation, 3 DOF for rotation, and 1 DOF for grasp). The SPIDAR-G (Space Interface Device for Artificial Reality with Grip) will allow users to interact with virtual objects naturally by manipulating two hemispherical grips located in the center of the device frame. We will show how to connect the strings between each vertex of grip and each extremity of the frame in order to achieve force feedback. In addition, methodologies will be discussed for calculating translation, orientation and grasp using the length of 8 strings connected to the motors and encoders on the frame. The SPIDAR-G exhibits smooth force feedback, minimized inertia, no backlash, scalability and safety. Such features are attributed to strategic string arrangement and control that results in stable haptic rendering. The design and control of the SPIDAR-G will be described in detail and the Space Graphic User Interface system based on the proposed SPIDAR-G system will be demonstrated. Experimental results validate the feasibility of the proposed device and reveal its application to virtual reality.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1063-1071
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• 2008

A piezoceramic unimoph actuator can produce a relatively larger actuation force and actuation displacement when a proper compressive load is applied during operation, because the compressive stress causes material nonlinear behavior in the piezoceramic layer and triggers mechanical buckling. In this paper, we examined effects of the actuator under compression on the flapping angle and aerodynamic force generation capability. Effects of wing shape and passive wing rotation angle on the aerodynamic force production were also investigated. The average vertical force acquired by a 2D CFD simulation for an artificial wing showed a good agreement with the measured one by the experiment.