• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.88-96
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• 2011

Underwater acoustic communication is applicable in various areas, such as ocean data collection, undersea exploration and development, tactical surveillance, etc. Thus, robot control system construction used for underwater-robot like AUV or ROV is essential in these areas. In this paper, we propose the Message Merging MAC($M^2$-MAC) protocol, which is suitable for real time robot control system, considering energy efficiency in important parts of underwater acoustic sensor network constitution. In this proposed MAC protocol, gateway node receives the data from robot nodes according to the time slots that were allotted previously. And messages delivered from base-station are generated to one MAC frame by buffering process. Finally, generated MAC frames are broadcasted to all robot nodes in the cluster. Our suggested MAC protocol can also be hybrid MAC protocol, which is successful blend of contention based and contention-free based protocol through relevant procedure with Maintenance&Sleep (M&S) period, when new nodes join and leave as an orphan. We propose mathematical analysis model concerned about End-to-End delay and energy consumption, which is important factor in constructing real-time robot control system. We also verify the excellence of performance according to comparison of existing MAC protocols with our scheme.

• Journal of The Korean Association of Information Education
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• v.18 no.2
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• pp.225-234
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• 2014

Robot programming allows students to plan an algorithm in order to solve a task, implement the algorithm, easily confirm the results of the implementation with a robot, and correct errors. Thus, robot programming is a problem solving process based on reflective thinking, and is closely related to students' metacognition. On this point, this research is conducted to develop a robot programming instructional model for tile enhancement of students' metacognition. The instructional processes of robot programming are divided into 5 stages (i.e., 'exploration of learning tasks', 'a teacher's modeling', 'preparation of a plan for task performance along with the visualization of the plan', 'task performance', and 'self-evaluation and self-reinforcement'), and core strategies of metacognition (i.e., planning, monitering, regulating, and evaluating) are suggested for students' activities in each stage. Also, in order to support students' programming activities and the use of metacognition, instructional strategies based on cognitive apprenticeship (i.e. modeling, coaching and scaffolding) are suggested in relation to the instructional model. In addition, in order to support students' metacognitive activities. the model is designed to use self-questioning, and questions that students can use at each stage of the model are presented.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.41-48
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• 2022

The purpose of this study is to compare the meaning of the experience of robot play in the free play time of 5-year-old children in daycare centers with the experience of 5-year-old children in the structural group activities of teachers. To this end, a total of 32 children (15 in the experimental group and 17 in the comparative group) aged 5 were conducted for 1 hour three times a week for 10 weeks. Robots were supported as toys in the classroom of the experimental group, and children in the comparative group freely experienced robot exploration and play during free play time, and children in the comparative group learned the robot's functions and performed structural group activities based on the 2019 Revised Nuri Curriculum national-level curriculum. As a result of analyzing the difference between pre-test and post-test, the use of robots in free play showed a significant effect in creativity and fluency of children, and a significant effect in expression of pleasure in playability. These results suggest that robots are meaningful as play materials in early childhood education, which aims for infant-led free play, and that it is worth studying the robot experiences of children in these free situations in the future.

• Journal of Intelligence and Information Systems
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• v.11 no.1
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• pp.153-167
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• 2005

In this paper, we consider the problem of exploring unknown environments with a mobile robot or an autonomous character agent. Traditionally, research efforts to address the space exploration problem havefocused on the graph-based space representations and the graph search algorithms. Recently EXPLORE, one of the most efficient search algorithms, has been discovered. It traverses at most min$min(mn, d^2+m)$ edges where d is the deficiency of a edges and n is the number of edges and n is the number of vertices. In this paper, we propose DFS-RTA* and DFS-PHA*, two real-time graph search algorithms for directing an autonomous agent to explore in an unknown space. These algorithms are all built upon the simple depth-first search (DFS) like EXPLORE. However, they adopt different real-time shortest path-finding methods for fast backtracking to the latest node, RTA* and PHA*, respectively. Through some experiments using Unreal Tournament, a 3D online game environment, and KGBot, an intelligent character agent, we analyze completeness and efficiency of two algorithms.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.516-523
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• 2009

Recently, the applications of unmanned robots are increasing in various fields including surveillance and reconnaissance, planet exploration and disaster relief. To perform their missions with success, the robots should be able to evaluate terrain's characteristics quantitatively and identify traversable regions to progress toward a goal using mounted sensors. Recently, the authors have proposed techniques that extract terrain information and analyze traversability for off-road navigation of an unmanned robot. In this paper, we examine the use of 3D world models(terrain maps) to classify obstacle and safe terrain for increasing the reliability of the proposed techniques. A world model is divided into several patches and each patch is classified as belonging either to an obstacle or a non-obstacle using three types of metrics. The effectiveness of the proposed method is verified on real terrain maps.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.2
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• pp.99-109
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• 2011

This paper presents implementation details of home appliance control system using personal communicator based on LN2440 single board computer, which recognizes hand-gesture of user, controls remote moving device such as mobile home server, robot etc. through delivery of proper control commands. Also, this paper includes details of design and implementation of home gateway and mobile home server. The implemented prototype can be utilized to develop various remote control system including a remote exploration robot, intelligent wheelchair based on general purpose embedded system.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.4
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• pp.279-285
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• 2016

In this paper, a platform design of caterpillar typed electrical vehicle is proposed. Nowadays, there have been many researches on mobile robots in the various ways. Many different fields such as military, exploration, agricultural assistance and disaster relief have applied the mobile robot. Design condition of stable angle, upset angle is reflect to caterpillar typed electrical vehicle. To experiment, developed a caterpillar typed electrical vehicle and design a driving controller. Developed caterpillar typed electrical vehicle is tested about operating and driving. Test environment is consisted of driving on flatland and climbing 15 degree and outdoor 40 degree slope. It is confirmed that developed tracked electric vehicular robot can driving and climbing.

• Journal of IKEEE
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• v.24 no.4
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• pp.991-997
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• 2020

Reinforcement learning has been applied mainly in sequential decision-making problems. Especially in recent years, reinforcement learning combined with neural networks has brought successful results in previously unsolved fields. However, reinforcement learning using deep neural networks has the disadvantage that it is too complex for immediate use in the field. In this paper, we implemented path planning algorithm for mobile robots using Q-learning, one of the easy-to-learn reinforcement learning algorithms. We used real-time Q-learning to update the Q-table in real-time since the Q-learning method of generating Q-tables in advance has obvious limitations. By adjusting the exploration strategy, we were able to obtain the learning speed required for real-time Q-learning. Finally, we compared the performance of real-time Q-learning and DQN.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.709-717
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• 2013

This paper presents the development of a specialized underwater leg with a manipulator function(convertible-to-arm leg) for the seabed walking robot named CRABSTER200(CR200). The objective functions of the convertible-to-arm leg are to walk on the seabed and to work in underwater for precise seabed exploration and underwater tasks under coastal area with strong tidal current. In order to develop the leg, important design elements including the degree of freedom, dimensions, mass, motion range, joint structure/torque/angular-speed, pressure-resistance, watertight capability and cable protection are considered. The key elements of the convertible-to-arm leg are realized through concept/specific/mechanical design and implementation process with a suitable joint actuator/gear/controller selection procedure. In order to verify the performance of the manufactured convertible-to-arm leg, a 25bar pressure-resistant and watertight test using a high-pressure chamber and a joints operating test with posture control of the CR200 are performed. This paper describes the whole design, realization and verification process for implementation of the underwater convertible-to-arm leg.

• Archives of Plastic Surgery
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• v.44 no.6
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• pp.550-553
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• 2017

Esophageal perforation is a rare but potentially fatal complication of robot-assisted thyroidectomy (RAT). Herein, we report the long-term outcome of an esophageal reconstruction with a jejunal free flap for esophageal rupture after RAT. A 33-year-old woman developed subcutaneous emphysema and hoarseness on postoperative day1 following RAT. Esophageal rupture was diagnosed by computed tomography and endoscopy, and immediate surgical exploration confirmed esophageal rupture, as well as recurrent laryngeal nerve injury. We performed a jejunal free flap repair of the 8-cm defect in the esophagus. End-to-side microvascular anastomoses were created between the right external carotid artery and the jejunal branches of the superior mesenteric artery, and end-to-end anastomosis was performed between the external jugular vein and the jejunal vein. The right recurrent laryngeal nerve injury was repaired with a 4-cm nerve graft from the right ansa cervicalis. Esophagography at 1 year after surgery confirmed that there were no leaks or structures, endoscopy at 1 year confirmed the resolution of vocal cord paralysis, and there were no residual problems with swallowing or speech at a 5-year follow-up examination. RAT requires experienced surgeons with a thorough knowledge of anatomy, as well as adequate resources to quickly and competently address potentially severe complications such as esophageal rupture.