• Research in Mathematical Education
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• v.27 no.1
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• pp.1-24
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• 2024

In this paper, the author analyzed characteristics of deep mathematics learning in problem solving and problem-posing classroom teaching. Based on a simple wrong plane geometry problem, the author describes the classroom experience how one expert Chinese mathematics teacher guides students to modify geometry problems from solution to investigation, and guides the students to learn how to pose mathematics problems in inquiry-based deep learning classroom. This also demonstrates how expert mathematics teacher can effectively guide students to teach deep learning in regular classroom.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1934-1935
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• 2011

In order for a service robot to perform several tasks, basically autonomous navigation technique such as localization, mapping, and path planning is required. The localization (estimation robot's pose) is fundamental ability for service robot to navigate autonomously. In this paper, we propose a new system for point pattern matching based visual global localization using spot lightings in ceiling. The proposed algorithm us suitable for system that demands high accuracy and fast update rate such a guide robot in the exhibition. A single camera looking upward direction (called ceiling vision system) is mounted on the head of the mobile robot and image features such as lightings are detected and tracked through the image sequence. For detecting more spot lightings, we choose wide FOV lens, and inevitably there is serious image distortion. But by applying correction calculation only for the position of spot lightings not whole image pixels, we can decrease the processing time. And then using point pattern matching and least square estimation, finally we can get the precise position and orientation of the mobile robot. Experimental results demonstrate the accuracy and update rate of the proposed algorithm in real environments.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.231-235
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• 2011

In these day, the number of people who have an abnormal posture caused by bad habit are increasing. Therefore, people suffer various disease and symptoms. For correcting the posture to cure, we need continuous monitor, expenditure of time and money. In this study, we develop a posture correcting aid system in other to monitor a posture continuously and leads to pose correctly and records postural variation which are attached to the neck and the waist. The devised system showed good potential for the correct posture guide and a cure of postural defect.

• Structural Engineering and Mechanics
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• v.42 no.6
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• pp.831-847
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• 2012

Impact from water-borne debris during tsunami and flood events pose a potential threat to structures. Debris impact forces specified by current codes and standards are based on rigid body dynamics, leading to forces that are dependent on total debris mass. However, shipping containers and other debris are unlikely to be rigid compared to the walls, columns and other structures that they impact. The application of a simple one-dimensional model to obtain impact force magnitude and duration, based on acoustic wave propagation in a flexible projectile, is explored. The focus herein is on in-air impact. Based on small-scale experiments, the applicability of the model to predict actual impact forces is investigated. The tests show that the force and duration are reasonably well represented by the simple model, but they also show how actual impact differs from the ideal model. A more detailed three-dimensional finite element model is also developed to understand more clearly the physical phenomena involved in the experimental tests. The tests and the FE results reveal important characteristics of actual impact, knowledge of which can be used to guide larger scale experiments and detailed modeling. The one-dimensional model is extended to consider water-driven debris as well. When fluid is used to propel the 1-D model, an estimate of the 'added mass' effect is possible. In this extended model the debris impact force depends on the wave propagation in the two media, and the conditions under which the fluid increases the impact force are discussed.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.23-31
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• 2023

The escalating settlements observed in concrete slab tracks pose a significant challenge in Korea, raising concerns about their adverse impact on the safe operation of high-speed railways and the substantial costs involved in restoration. A primary contributor to these settlements is identified as the utilization of rock materials sourced from tunnel construction, incorporated into the lower subgrade without the requisite soil mixing to achieve an appropriate particle size distribution. This study employs numerical analysis to evaluate the efficacy of partial reinforcement in reducing settlements in rock-filled lower subgrades. Column-shaped reinforcement areas strategically positioned at regular intervals in the lower subgrade induce soil arching in the upper subgrade, leading to a concentration of soil loads on the reinforced areas and consequent settlement reduction. The analysis employs finite element methods to investigate the influence of the size, stiffness, and spacing of the reinforced areas on settlement reduction in the lower subgrade. The numerical results guide the formulation of an optimal design approach, proposing a method to determine the minimum spacing required for reinforcements to effectively limit settlements within acceptable bounds. This research contributes valuable insights into addressing the challenges associated with settlement in concrete slab tracks, offering a basis for informed decision-making in railway infrastructure management.

• Korean Journal of Cognitive Science
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• v.34 no.2
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• pp.85-110
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• 2023

The gaze cueing effect appears as detecting a target rapidly and accurately when the direction of others' gaze corresponds with the location of the visual target. The gaze cue can be affected by the orientation of the face. The gaze cueing effect is strong when the face is presented upright, but the effect has only been observed in some studies when the face is presented inverted(e.g., Tipples, 2005). This study aimed to examine whether the gaze can operate as a cue to guide attention with upright faces, and to add variables that can affect the gaze cue, such as the orientation of the face, the orientation of the background, and a time interval between the gaze cue and the target(SOA). Furthermore, it systematically manipulated these variables to explore whether the gaze cueing effect can be observed under the various conditions. The results showed a significant gaze cueing effect even on the inverted face, contrasting with previous studies. These findings were consistently observed when the background stimulus was absent(Experiment 1) and present(Experiments 2 and 3). However, there was no significant interaction in the orientations between the face and the background. Moreover, in the short SOA(150 ms), we found a significant gaze cueing effect in conditions of every face and background orientation, whereas there was no significant gaze cueing effect in the long SOA(1000 ms). By presenting a consistent observation of the gaze cueing effect under the short SOA(150ms) even in the inverted faces, the results of this study pose questions about the reliability and repeatability of previous studies that did not report significant results of gaze cueing effects in that faces. Furthermore, our results are meaningful in providing additional evidence that attention can be guided toward the direction of the gaze even in various directions of the face and background.