• Journal of the Korea Society for Simulation
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• v.27 no.3
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• pp.23-36
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• 2018

Discrete Event System Specification (DEVS) has been used for decades as it provides sound semantics for hierarchical modular specification of discrete event systems. Instead of the mathematical specification, the DEVS diagram, based on the structured DEVS formalism, has provided more intuitive and convenient representation of complex DEVS models. This paper proposes a clean room process for implementation and verification of a DEVS diagram model specification into a simulation software source code. Specifically, it underlies a sequence of transformation steps from conformance and integrity checking of a given diagram model, translation into a corresponding tabular model, and finally conversion to a simulation source code, with each step being inversely verifiable for traceability. A simple example helps developers to understand the proposed process with associated transformation methods; a case study shows that the proposed process is effective for and adaptable to practical simulation software development.

• Smart Structures and Systems
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• v.23 no.6
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• pp.565-577
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• 2019

One of the most effective countermeasures for mitigating cable vibration is to install mechanical dampers near the anchorage of the cable. Most of the dampers used in the field are so-called passive dampers where their parameters cannot be changed once designed. The parameters of passive dampers are usually determined based on the optimal damper force obtained from the universal design curve for linear dampers, which will provide a maximum additional damping for the cable. As the optimal damper force is chosen based on a predetermined principal vibration mode, passive dampers will be most effective if cable undergoes single-mode vibration where the vibration mode is the same as the principal mode used in the design. However, in the actual engineering practice, multi-mode vibrations are often observed for cables. Therefore, it is desirable to have dampers that can suppress different modes of cable vibrations simultaneously. In this paper, MR dampers are proposed for controlling multi-mode cable vibrations, because of its ability to change parameters and its adaptability of active control without inquiring large power resources. Although the highly nonlinear feature of the MR material leads to a relatively complex representation of its mathematical model, effective control strategies can still be derived for suppressing multi-mode cable vibrations based on nonlinear modelling, as proposed in this paper. Firstly, the nonlinear Bouc-wen model is employed to accurately portray the salient characteristics of the MR damper. Then, the desired optimal damper force is determined from the universal design curve of friction dampers. Finally, the input voltage (current) of MR damper corresponding to the desired optimal damper force is calculated from the nonlinear Bouc-wen model of the damper using a piecewise linear interpolation scheme. Numerical simulations are carried out to validate the effectiveness of the proposed control algorithm for mitigating multi-mode cable vibrations induced by different external excitations.

• Education of Primary School Mathematics
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• v.25 no.3
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• pp.233-249
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• 2022

Measurement plays an important role in both school mathematics and real life. Among the measurement areas, length is the first to learn and is the basis for measurement. Time is measured in its own way and is characterized by being the most abstract. This study attempted to analyze elementary mathematics textbooks and representations in real life to examine how the length and time of learning in school mathematics differ from those represented in real life. Based on this, we tried to derive implications for the direction of measurement education and elementary math textbooks. As a result of the analysis, the concept of length was used the same in real life and school mathematics. However, terms such as distance, depth, and height were not defined, and the representation of the approximate value was presented in a fragmentary form. In addition, there were parts where students were likely to feel confused in school mathematics and real life, such as the same units such as 'minutes and seconds' were used in time. Therefore, considering these differences, it is necessary to consider the direction of composition of math textbooks and teaching and learning so that students can connect school mathematics and real life and understand widely about measurement concepts.

• Communications of Mathematical Education
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• v.30 no.2
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• pp.199-223
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• 2016

The purpose of this study is to investigate how first and second graders in middle school take in integrated understanding about the concept of function. The data was collected through the questionnaire conducted by the first and second-year students at A, B middle school in Cheongju. The questionnaire consisted of 14 questions related to the extent of understanding a concept of function, the ability to express function and to translate function. The results are summarized as follows. First, the percentage of correct answer made a difference according to the types of representation. Questions leading students to translate a task into a table or an equation showed quite high correct response rates. However, questions asking students to translate a task into graphs showed high incorrect responses. Second, the result shows that students have the different viewpoints depending on their grades when they have to determine whether the suggested situation belongs to function. The first-year students tended to consider function as the concept of 'definition'. On the other hand, the second-year students emphasized 'equation' of function. Finally, only a few students can distinguish the various situations and representations into the definition of function. This result shows that students didn't get the integrated understanding of the concept of function.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.277-297
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• 2020

The purpose of this study was to identify and compare the mathematics educational values of pre-service and in-service elementary school teachers. For this purpose, we implemented a questionnaire investigating mathematics educational values and used principal component analysis which resulted in six components. These components were named as fun, problem-solving, representation, computation, ability, and explanation through systematic labeling processes. Both pre-service and in-service elementary school teachers considered problem-solving the most important and there was no statistical difference between the teacher groups. They also considered fun the least important and in-service elementary school teachers regarded it more important than pre-service counterparts did. All value components except explanation were regarded as important by in-service elementary school teachers, fourth-year pre-service teachers, and first-year pre-service teachers in order. The result of noticeable differences between pre-service and in-service elementary school teachers implies that actual teaching experience may affect teachers' mathematics educational values more than teacher preparation programs. Based on these findings, we need to discuss what should be regarded as important and worthwhile in teacher preparation programs to establish mathematics educational values for pre-service teachers. We also need to confirm whether the mathematics educational values by in-service elementary school teachers may be in line with what has been pursued in the national mathematics curriculum.

• School Mathematics
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• v.18 no.2
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• pp.257-275
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• 2016

The purpose of this study was to investigate the impact of multiple representations on students' understanding of fractions, decimals, and percent. The instructional approach integrating multiple representations was compared to traditional algorithmic instruction, a form of direct instruction. To examine and compare the impact of multiple representations instruction with traditional algorithmic instruction, pre and post tests consisting of five similar items were administered with 87 middle school students. Students' scores in these two tests and their problem solving processes were analyzed quantitatively and qualitatively. The quantitative results indicated that students taught by traditional algorithmic instruction showed higher scores on the post-test than students in the multiple representations group. Furthermore, findings suggest that instruction using multiple representations does not guarantee a positive impact on students' understanding of mathematical concepts. Qualitative results suggest that the limited use of multiple representations during a class may have hindered students from applying their use in novel problem situations. Therefore, when using multiple representations, teachers should employ more diverse examples and practice with multiple representations to help students to use them without error.

• Communications of Mathematical Education
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• v.33 no.2
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• pp.105-122
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• 2019

In Korean textbooks, by T(x,y) = (x+a, y+b) where a and b are horizontal and vertical changes respectively, an arbitrary point on the original figure f(x, y) = 0 has been expressed as a point (x, y) and a point on a translated figure f(x-a, y-b) = 0 has been expressed as a point (x', y'). If an arbitrary point on a figure f(x, y) = 0 is expressed as a point (x, y), then a point (x, y) and a figure f(x, y) = 0 are different targets but the same characters are used. In this following study, there were found that the expressions in these textbooks were stuck for more than 50 years, so students' thoughts were stiff. And therefore these are a need to be improved so that those things are studied as follows. First, inducing a formula, what are the students' responses like when were expressed differently from textbooks? Second, based on the results reviewed, how will the expressions of the textbook be revised? Third, how do the students respond to the modified expressions? As the result, a point on the original figure were expressed differently from textbooks and a point on a translated figure was put as a point (x, y), and about it, all of the students surveyed said that this improved expressions made in the study were easier.

• School Mathematics
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• v.14 no.1
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• pp.85-107
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• 2012

Problem solving is important in school mathematics as the means and end of mathematics education. In elementary school, inductive reasoning is closely linked to problem solving. The purpose of this study was to examine ways of improving problem solving ability through analysis of inductive reasoning process. After the process of inductive reasoning in problem solving was analyzed, five different stages of inductive reasoning were selected. It's assumed that the flow of inductive reasoning would begin with stage 0 and then go on to the higher stages step by step, and diverse sorts of additional inductive reasoning flow were selected depending on what students would do in case of finding counter examples to a regulation found by them or to their inference. And then a case study was implemented after four elementary school students who were in their sixth grade were selected in order to check the appropriateness of the stages and flows of inductive reasoning selected in this study, and how to teach inductive reasoning and what to teach to improve problem solving ability in terms of questioning and advising, the creation of student-centered class culture and representation were discussed to map out lesson plans. The conclusion of the study and the implications of the conclusion were as follows: First, a change of teacher roles is required in problem-solving education. Teachers should provide students with a wide variety of problem-solving strategies, serve as facilitators of their thinking and give many chances for them ide splore the given problems on their own. And they should be careful entegieto take considerations on the level of each student's understanding, the changes of their thinking during problem-solving process and their response. Second, elementary schools also should provide more intensive education on justification, and one of the best teaching methods will be by taking generic examples. Third, a student-centered classroom should be created to further the class participation of students and encourage them to explore without any restrictions. Fourth, inductive reasoning should be viewed as a crucial means to boost mathematical creativity.

• Cartoon and Animation Studies
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• s.51
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• pp.391-411
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• 2018

The purpose of this thesis is to examine ontology of digital photo image based on a Simulacre concept of Gilles Deleuze & Jean Baudrillard. Traditionally, analog image follows the logic of reproduction with a similarity with original target. Therefore, visual reality of analog image is illuminated, interpreted, and described in a subjective viewpoint, but does not deviate from the interpreted reality. However, digital image does not exist physically but exists as information that is made of mathematical data, a digital algorithm. This digital image is that newness of every reproduction, that is, essence of subject 'once existing there' does not exist anymore, and does not instruct or reproduce an outside target. Therefore, digital image does not have the similarity and does not keep the index instruction ability anymore. It means that this digital image is converted into a virtual area, and this is not reproduction of already existing but display of not existing yet. This not-being of digital image changes understanding of reality, existence, and imagination. Now, dividing it into reality and imagination itself is meaningless, and this does not make digital image with technical improvement but is a new image that is basically completely different from existing image. Eventually, digital image of the day passes step to visualize an existent target, nonexistent things have been visualized, and reality operates virtually. It means that digital image does not reproduce our reality but reproduces other reality realistically. In other words, it is a virtual reproduction producing an image that is not related to a target, that is to say Simulacre. In the virtually simulated world, reality has an infinite possibility, and it is not a picture of the past and present and has a possibility as the infinite virtual that is not fixed, is infinitely mutable, and is not actualized yet.

• Korean Journal of Childcare and Education
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• v.10 no.5
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• pp.229-248
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• 2014

The purpose of this study is to draw guidelines on how to select traditional games that would efficiently help and develop multiple intelligences in children. Guidelines standard of section inquiries were prepared through a Delphi survey targeting twenty experts in early childhood education and traditional games. As a result, linguistic intelligence questions regarding writing, listening, speaking and vocabulary acquisition were selected. logical-mathematical intelligence questions regarding strategy, counting, patterns, hypothesis, verification, and comparing, contrasting, calculating ability were selected. Spatial intelligence questions regarding drawing, coloring, representation activities, operating and creating were selected, physical performance intelligence questions regarding global muscles, eye-hand coordination, flexibility, accommodation force, balance, agility and muscular strength were selected. Musical intelligence included questions about singing, and playing musical instruments. Interpersonal intelligence included perspective-taking, role-sharing, cooperation and discussion. For intrapersonal intelligence questions regarding personal significance-ties, planning-decision making, emotional expression and problem solving were selected. Finally, in relation to naturalist intelligence, questions regarding living organisms, inanimate objects and seasons were selected. In addition, traditional games were analyzed based on the finalized guidelines, and the results showed that each of the traditional games would not only work with one intelligence at a time but with other different intelligence as well. In the light of that, the study confirmed the validity of the guidelines on how to select traditional games that would develop multiple intelligences in children.