• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.663-668
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• 1991

In order to navigate, mobile robot needs to avoid obstacles on his way. We describe a stereo vision method for detecting obstacles on the floor ground. With the knowledge of floor geometry, stereo images are transformed so that the relative views of obstacle to the floor are seen. After comparing the transformed images, obstacles information such as location and size are extracted and determined from the local disparities. Some experimental results are shown.

• Journal of Educational Research in Mathematics
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• v.9 no.1
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• pp.133-150
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• 1999

In this study, we tried to make histo-genetic analyses necessary to identify epistemological obstacles on the function concepts. Historical development on the function concept was analysed. From these analyses, we obtain epistemological obstacles as follows: the perception of changes in the surrounding world, mathematical philosophy, number concepts, variable concepts, relationships between independent variables and dependent variables, concepts of definitions.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.345-348
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• 1994

A real-time collision avoidance algorithm for an AMR (Autonomous Mobile Robot) using the Distance Transform and Vector Field Histogram is studied. This approach enables AMR to find a collision-free path with the unknown obstacles. All system parameters including positions of the obstacles can be accepted using a mouse icon and all the obtained trajectories can be displayed on a computer monitor in graphics.

• The Journal of Korea Robotics Society
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• v.4 no.2
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• pp.163-168
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• 2009

In this paper, a new driving mechanism of security robotswhich should overcome obstacles with stability even though movingin high speed is introduced. The driving mechanism has spring-based suspension and two wheels positively necessary to overcome obstacles. From the driving mechanism, it is mainly discussed how we can decrease overshoot and impulse occurred when the robot is in the process of overcoming obstacles. Finally, design parameters of the driving mechanism which guarantees stable motion while overcoming obstacles is deduced based on simulation results. Experiments are also followed to demonstrate how well the manufactured system works in its early stage of the practical use.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.918-925
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• 2017

This paper presents a path planning problem for multi-robot system in the environment with dynamic obstacles. In order to guide the robots move along a collision-free path efficiently and reach the goal position quickly, a navigation method based on fuzzy logic controllers has been developed by using proximity sensors. There are two kinds of fuzzy controllers developed in this work, one is used for obstacle avoidance and the other is used for orientation to the target. Both static and dynamic obstacles are included in the environment and the dynamic obstacles are defined with no type of restriction of direction and velocity. Here, the environment is unknown for all the robots and the robots should detect the surrounding information only by the sensors installed on their bodies. The simulation results show that the proposed method has a positive effectiveness for the path planning problem.

• Industrial Engineering and Management Systems
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• v.12 no.1
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• pp.63-72
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• 2013

The aim of this paper is to analyse the impacts of R&D cooperation and obstacles to technological innovation on the innovation failure of the Korean manufacturing firms. Two hierarchical regression models including interaction variables are employed for the analysis. Some interesting findings are: first, almost all the obstacles have positive and significant effects on the failure. Second, R&D cooperation positively or negatively moderates the impact of obstacles to technological innovation on the innovation failure, although R&D cooperation itself is not directly related to the failure. Third, the interaction effects between the cooperation and the obstacles influence the failure in various manners. This study is expected to help manufacturing firms which are under unfavourable environments to formulate their cooperation strategies successfully based on what they learn from the failure.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.84-90
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• 2012

In unmanned vehicles' navigation, the shapes of obstacles are generally irregular and complex. The motion of vehicles based on the range sensor system such as ultrasonic sensors or laser sensors can be unstable due to the irregular shape of the obstacles. In this case, to generate stable trajectory of unmanned vehicles equipped with range sensors, we need an approach that can simplify an obstacle's irregular shape information. In this paper, we propose the trajectory generation algorithm that an vehicle can stably navigate in the environments where irregular shaped obstacles are scattered. The proposed method is verified through the analysis of vehicle's trail and direction data acquired by simulations and implementations.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.17-29
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• 2001

In this paper, we designed the hybrid path generation method which is named CAPM(Continuous path generation method based on artificial Potential field) that is able to be used in the obstacles environment. This CAPM was designed so that it puts together two obstacle avoidance algorithm-the continuous path generation method(CPGM) and the artificial potential field method(APFM). Here, the CAPM generate the safety path using continuous path curvature. But, this method has demerits when used in obstacles environment in which are closely located. Another method which is named the APFM generates the path with the artificial potential field in the obstacles environment. But, It has local minima in certain places and unnecessarily calculates the path in which obstacles are not located. So, the CAPM was designed for autonomous underwater vehicle(AUV) obstacle avoidance. As the result of simulation, it was confirmed that the CAPM can be applied to a safe path generation for AUV.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.304-306
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• 2001

This paper presents the obstacle avoidance of a biped walking robot using GA-Fuzzy algorithm. In the case of our previous studies the surface has been assumed to be flat. For the case of the environment with obstacles, however, the walking robot might be unnatural. Thus, we considered the surface contained obstacles that the robot can pass through. We propose the optimal leg trajectory data-base by using genetic algorithm and optimal leg trajectory movement about obstacles that exist in front of the robot using fuzzy approach. It is shown that the robot can move more naturally on the surface that contains obstacles.

• Journal of Educational Research in Mathematics
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• v.12 no.1
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• pp.29-48
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• 2002

The purpose of this paper is to investigate the transfer in mathematics learning, especially focussing on arithmetic and algebra. There are many obstacles at the stage of transfer in learning. In the case of mathematics, each learning contents are definitely categorized by the learning level, therefore these obstacles are more happened than other subjects. First of all, this paper investigates the historical transfer from arithmetic to algebra by Sfard's perspectives. And we define prealgebra as the stage between arithmetic and algebra, which may be revised obstacles or misconceptions happened in the early algebra learning. Also, this paper discusses various obstacles and concrete examples happened in the transfer from arithmetic to algebra. To advance the understanding in the learning of algebra, we consider the core contents of the algebra learning which should be stressed at the prealgebra stage. Finally we present the teaching units of (pre)algebra which are sequenced from the variable concepts to equations.