• Journal of Institute of Control, Robotics and Systems
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• v.18 no.12
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• pp.1106-1114
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• 2012

To achieve synchronized motion between a wearable robot and a human user, the redundancy must be resolved in the same manner by both systems. According to the seven DOF (Degrees of Freedom) human arm model composed of the shoulder, elbow, and wrist joints, positioning and orientating the wrist in space is a task requiring only six DOFs. Due to this redundancy, a given task can be completed by multiple arm configurations, and thus there exists no unique mathematical solution to the inverse kinematics. This paper presents analysis on the kinematic and dynamic aspect of the human arm movement and their effect on the redundancy resolution of the human arm based on a seven DOF manipulator model. The redundancy of the arm is expressed mathematically by defining the swivel angle. The final form of swivel angle can be represented as a linear combination of two different swivel angles achieved by optimizing different cost functions based on kinematic and dynamic criteria. The kinematic criterion is to maximize the projection of the longest principal axis of the manipulability ellipsoid for the human arm on the vector connecting the wrist and the virtual target on the head region. The dynamic criterion is to minimize the mechanical work done in the joint space for each two consecutive points along the task space trajectory. As a first step, the redundancy based on the kinematic criterion will be thoroughly studied based on the motion capture data analysis. Experimental results indicate that by using the proposed redundancy resolution criterion in the kinematic level, error between the predicted and the actual swivel angle acquired from the motor control system is less than five degrees.

• Journal of Korea Game Society
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• v.17 no.2
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• pp.27-34
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• 2017

The study is to drive right users' attitude of internet and smart phones by providing the rewards. It consisted of 4 different types of no compensation, praise card, achievement sticker and cash and its effect on user's behavior was statistically tested. 24 children in grades four through six participated in the study. The task in this study was game of mathematical calculation. The subjective satisfaction about the reward and heart response during the game task were measured. As the results, inactivation of sympathetic and parasympathetic was observed in the case of no compensation while activation in the case of praise card. Therefore, the praise card was observed in greater commitment and satisfaction than the other rewards. The difference between non-compensation and compensation was significant in the subjective satisfaction, but not difference between compensations.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.208-222
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• 2021

Managing with the presence of sea ice is the primary challenge in the operation of floating platforms in the Arctic region. It is widely accepted that offshore structures operating in Arctic conditions need station-keeping methods as well as ice management by icebreakers. Dynamic Positioning (DP) is one of the station-keeping methods that can provide mobility and flexibility in marine operations. The presence of sea ice generates complex external forces and moments acting on the vessel, which need to be counteracted by the DP system. In this paper, an icevaning control algorithm is proposed that enables Arctic offshore vessels to perform DP operations. The proposed icevaning control enables each vessel to be oriented toward the direction of the mean environmental force induced by ice drifting so as to improve the operational safety and reduce the overall thruster power consumption by having minimum external disturbances naturally. A mathematical model of an Arctic offshore vessel is summarized for the development of the new icevaning control algorithm. To determine the icevaning action of the Arctic offshore vessel without any measurements and estimation of ice conditions including ice drift, task and null space are defined in the vessel model, and the control law is formulated in the task space. A backstepping technique is utilized to handle the nonlinearity of the Arctic offshore vessel's dynamic model, and the Lyapunov stability theory is applied to guarantee the stability of the proposed icevaning control algorithm. Experiments are conducted in the ice tank of the Korea Research Institute of Ships and Ocean Engineering to demonstrate the feasibility of the proposed approach.

• School Mathematics
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• v.9 no.4
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• pp.487-506
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• 2007

The aims of this study is figure out the characteristics of justification patterns and mathematical representation which are derived from 14 mathematically gifted middle school students in the process of solving the spatial tasks on Archimedean solid. This study shows that mathematically gifted students apply different types of justification such as empirical, or deductive justification and partial or whole justification. It would be necessary to pay attention to the value of informal justification, by comparing the response of student who understood the entire transformation process and provided a reasonable explanation considering all component factors although presenting informal justification and that of student who showed formalization process based on partial analysis. Visual representation plays an valuable role in finding out the Idea of solving the problem and grasping the entire structure of the problem. We found that gifted students tried to create elaborated symbols by consolidating mathematical concepts into symbolic re-presentations and modifying them while gradually developing symbolic representations. This study on justification patterns and mathematical representation of mathematically gifted students dealing with spatial geometry tasks provided an opportunity for understanding their the characteristics of spacial geometrical thinking and expending their thinking.

• Food Science of Animal Resources
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• v.29 no.2
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• pp.278-282
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• 2009

Previous studies indicate that BF-7 enhances learning and memory in normal and elderly individuals. Here, we evaluated whether milk containing BF-7 (BF-7 milk) could improve the brain function, with thirty normal university students $(21{\pm}1.2 years)$. Two versions of the Paced Auditory Serial Addition Test were used under double-blinded conditions to measure the efficacy of BF-7 milk on learning and memory, especially working memory and attention, and on mathematical ability. As a result, BF-7 milk improved the accuracy of the task more than 3-fold. Furthermore, BF-7 milk protected cultured neuronal cells from 3-hydroxykynurenine, a normal endogenous brain stress agent. These results indicate that BF-7 milk enhances memory, attention and mathematical ability in normal persons.

• School Mathematics
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• v.11 no.4
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• pp.583-605
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• 2009

This research aims to examine the characteristics and main subjects of the mathematics class-criticism by elementary' teachers. In this aim, we analyzed the mathematics class-criticism by the 11 elementary teachers. As the results of this research, the elementary teachers criticized the mathematics class while understanding and describing the class as it is. And mathematics class-criticism by elementary teachers showed contextual and situational characteristics. Furthermore, the main subjects of mathematics class-criticism by elementary teachers were identified as mathematical communication, teacher's question to foster the students' mathematical thinking, appropriateness of task, motivation for students, concrete operational activity, appropriateness on teacher's mathematical behavior and teacher's use of mathematical term, experience of inductive reasoning. While, we identified the significance of mathematics class-criticism for elementary teachers. The elementary teachers pointed out the necessity and importance of the mathematics class-criticism on the mathematics class in usual context.

• Education of Primary School Mathematics
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• v.6 no.2
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• pp.75-84
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• 2002

After entering an elementary school, in fact, a number of children regard mathematics as one of very difficult subjects because of its abstractiveness. This is caused by the fact that their basic thinking power is not yet formed or they can not understand the special quality of mathematics. So this article emphasizes the need to build up the higher logical thought and a basic mathematical concept at the lower grade elementary school stage in which the loaming activity on mathematics begins in earnest, that is, at the stage before having an experience on the calculating activity using numbers. But at present the lower grade elementary school students in our country do not understand the special quality of mathematics composed of a various symbolic system and lay stress upon mathematics learning attached to the calculative activity. In order to make the right mathematical concept of the lower grade elementary school, the basic knowledge and ability as follows is sure to be formed. 1) the foundational logical manipulation activity and knowledge 2) the using ability of the sign and symbolic system At the stage on which mathematics learning activity begins, it is a very important task to make the right concept of the abstractive math and nurse the capability for finding mathematical relations covered under the sign system through the continuos loaming activity on . Through the basic logical manipulation activity and the game activity of sign for lower grade elementary school students mentioned in this article, they can not only foster the higher level logical thinking power and the foundational calculative ability but also bring up the interest on the activity of establishing a new problem solving strategy.

• The Mathematical Education
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• v.58 no.3
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• pp.367-381
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• 2019

This investigation engaged elementary and middle school pre-service teachers in a task of modeling and explaining the magnitude of $0.14m^2$ and examined their responses. The study analyzed both successful and unsuccessful responses in order to reflect on the patterns of misconceptions relative to pre-service teachers' prior knowledge. The findings suggest a need to promote opportunities for pre-service teachers to make connections between different domains through meaningful tasks, to reason abstractly and quantitatively, to use proper language, and to refine conceptual understanding. While mathematics teacher educators (MTEs) could use such mathematical tasks to identify the mathematical content needs of pre-service teachers, MTEs generally use instructional time to connect content and pedagogy. More importantly, an early and consistent exposure to a combined experience of mathematics and pedagogy that connects and deepens key concepts in the program's curriculum is critical in defining the important content knowledge for K-8 mathematics teachers.

• The Mathematical Education
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• v.60 no.1
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• pp.1-19
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• 2021

This study investigates students' conceptions of fractions from a measurement approach while providing a technological environment designed to support students' understanding of the relationships between quantities and adjustable units. 13 third-graders participated in this study and they were involved in a series of measurement tasks through task-based interviews. The tasks were devised to investigate the relationship between units and quantity through manipulations. Screencasting videos were collected including verbal explanations and manipulations. Drawing upon the theory of semiotic mediation, students' constructed concepts during interviews were coded as mathematical words and visual mediators to identify conceptual profiles using a fine-grained analysis. Two students changed their strategies to solve the tasks were selected as a representative case of the two profiles: from guessing to recursive partitioning; from using random units to making a relation to the given unit. Dragging mathematical objects plays a critical role to mediate and formulate fraction understandings such as unitizing and partitioning. In addition, static and dynamic representations influence the development of unit concepts in measurement situations. The findings will contribute to the field's understanding of how students come to understand the concept of fraction as measure and the role of technology, which result in a theory-driven, empirically-tested set of tasks that can be used to introduce fractions as an alternative way.

• Journal of the Korean School Mathematics Society
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• v.25 no.2
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• pp.195-224
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• 2022

In this study, pre-service mathematics teachers cultivated technology content teaching knowledge (TPACK) in the regular curriculum of the College of Education. The course was designed to enhance pre-service teachers' mathematical communication skills by using an application, which is a mobile mathematics learning content for the development of group creativity of high school students. The educational program to improve mathematics teaching expertise using the application for group creativity expression consists of pre-education, goal setting, planning, teaching at school, and evaluation. In this process, pre-service teachers evaluated technology tools. They also wrote a task dialogue, lesson play, reflective journal, and lesson plan to guide high school students to develop group creativity in both app activities. As a result of the educational program, pre-service mathematics teachers cultivated TPACK and enhanced their mathematical communication skills with high school students to develop group creativity.