• Journal of the Korean School Mathematics Society
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• v.8 no.2
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• pp.183-201
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• 2005

Illustrations and letters are two components of school textbooks. In the case of low grades of elementary school, textbook's illustrations play an important role in learning because many parts of curriculums(lessons) are represented by the visual forms through illustrations. So elementary mathematics textbook's illustrations have to make clear mathematical concepts and principles by visual simplification and bring out of the interest and motivation of elementary school students' learning. In this paper, we analysed the external and content aspects of textbook's illustrations, focusing on the textbook of the second grade. We investigated number, kindness, size, ratio, and clearness of illustrations in regard to external aspects. On the aspects of content, we analysed the role of illustrations and the degree of agreement with contents. Also we classified types of error in the textbook's illustrations and presented examples of errors which was found.

• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.29-34
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• 2005

A mis-handling of the ship operators, treated as one qf the main causes of a ship accidents, normally has caused a ship to collide with obstacles like a reef, a rock and other ships etc. since their ability has been declining little by little even though the port conditions have been getting worse. The ship needs a highly sophisticated technology as her size and speed increase as the ship have been demanded. For example, Auto Avoidance Control System gradually has been receiving a growing interest to control the entire ship safely. From that purpose, this research has been done. The research was based on the MMG mathematical model, used Surge-Sway-Yaw-Roll motion equation and Fuzzy theory for calculating the collision-risk Also the research successively was done when the ship encountered continual multitude ships.

• Korean Journal of Logic
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• v.12 no.2
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• pp.141-170
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• 2009

We can witness the recent surge of interest in the controversy over the scientific status of mathematics among Jesuit Aristotelians around 1600. Following the lead of Wallace, Dear, and Mancosu, I propose to look into this controversy in more detail. For this purpose, I shall focus on Biancani's discussion of scientiae mediae in his dissertation on the nature of mathematics. From Dear's and Wallace's discussions, we can gather a relatively nice overview of the debate between those who championed the scientific status of mathematics and those who denied it. But it is one thing to fathom the general motivation of the disputation, quite another to appreciate the subtleties of dialectical strategies and tactics involved in it. It is exactly at this stage when we have to face some difficulties in understanding the point of Biancani's views on scientiae mediae. Though silent on the problem of scientiae mediae, Mancosu's discussions of the Jesuit Aristotelians' views on potissima demonstrations, mathematical explanations, and the problem of cause are of utmost importance in this regard, both historically and philosophically. I will carefully examine and criticize some of Mancosu's interpretations of Piccolomini's and Biancani's views in order to approach more closely what was really at stake in the controversy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1036-1044
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• 2012

Thanks to progressive development of IT technology, the number of intelligent devices communicating each other through an In-Vehicle Network(IVN) has been steadily increasing. It is expected that the required network bandwidth and network nodes for vehicle control in 2015 will be increased by two times and one and half times as compared to in 2010, respectively. As a result, many researchers in automotive industry has showed a significant interest on industrial Ethernets, such as EtherCAT and TTEthernet. This paper addresses an analysis on transmission delay and fault recovery performance with an EtherCAT network which is being considered as an IVN. A mathematical model based on the analysis is verified through a set of experiments using an experimental network setup.

• Education of Primary School Mathematics
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• v.20 no.4
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• pp.305-319
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• 2017

In the process of finding the triangle height, 26 students in the 6th grade were surveyed to understand the students' triangle height through the eye movement data and to investigate the cognitive load of the students. As a result, the correctness rate of the pre-test was significantly increased in the post-test, and the frequency and retention of gaze data were smaller in the post-test than in the AOI of each question. The Participants's subjective cognitive load indicated that it was more difficult to understand the concept of rotated triangles compared with upright triangles that were parallel to the ground. More frequent and more retentions in the eye-tracking data were detected in the right triangles and acute triangles by rotating configuration. Eye movement data show that eye tracking technology can provide an objective measure of students' cognitive load for feedback on instructional design.

• Steel and Composite Structures
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• v.34 no.4
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• pp.511-524
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• 2020

In this research, a simple four-variable trigonometric integral shear deformation model is proposed for the static behavior of advanced functionally graded (AFG) ceramic-metal plates supported by a two-parameter elastic foundation and subjected to a nonlinear hygro-thermo-mechanical load. The elastic properties, including both the thermal expansion and moisture coefficients of the plate, are also supposed to be varied within thickness direction by following a power law distribution in terms of volume fractions of the components of the material. The interest of the current theory is seen in its kinematics that use only four independent unknowns, while first-order plate theory and other higher-order plate theories require at least five unknowns. The "in-plane displacement field" of the proposed theory utilizes cosine functions in terms of thickness coordinates to calculate out-of-plane shear deformations. The vertical displacement includes flexural and shear components. The elastic foundation is introduced in mathematical modeling as a two-parameter Winkler-Pasternak foundation. The virtual displacement principle is applied to obtain the basic equations and a Navier solution technique is used to determine an analytical solution. The numerical results predicted by the proposed formulation are compared with results already published in the literature to demonstrate the accuracy and efficiency of the proposed theory. The influences of "moisture concentration", temperature, stiffness of foundation, shear deformation, geometric ratios and volume fraction variation on the mechanical behavior of AFG plates are examined and discussed in detail.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.3
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• pp.807-825
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• 2010

Educational interest has been paid to ADHD students. Because of being easily distracted, lacking concentration, and committing hyperactive acts, they lag much behind other students in academic grades and their teachers have many difficulties in teaching them. This study aims to provide a case of enhancing an ADHD student's fraction-related achievement. To do this, we investigated his mathematical abilities in a preliminary study, devised an individualized teaching for the fractions unit, and applied them to him. And analyzing the results from observations and interviews of the student we can induce the following results: First, the ADHD student showed such types of errors in relation to fraction as lack of the concept of dividing into equal parts, lack of the concept of numerator and denominator, and errors in adding or subtracting fractions anc mixed fractions whose denominators were the same. And secondly, the fraction-related achievements of the ADHD student have improved thanks to the systematic teaching plan based on the accurate understanding of his academic gap relative to other students, his learning attitude, and his time difference. In addition, this study suggests several implications for ADHD students' learning of fractions.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.3
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• pp.843-863
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• 2010

The basic purpose of 2007 revision curriculum is content of activity oriented, management of differentiated instruction, communication, introduction of story mathematics, mathematical exploration and problem solving ability and so on. In this paper, we investigate some characteristics of number teaching in the primary school of New Zealand. Especially, focused on materials and methods and so on. So we've got the following results. First, there are no fundamental differences in materials and methods in teaching number between Korea and New Zealand but in New Zealand there are no national textbook like us so there is a possibility not to teach number systematically like our Korea. On the contrary, they divide number region from one to six level and are offering achievement objects, suggestive learning experiences, sample assessment activities for each level and also they do not guide activities itself in detail like us and so have learners themselves think about the given problems. Second, there is a strategy stage in getting knowledge about number in New Zealand and so children can take advantage of this steps according to the type of problems. Third, it must be developed some materials and idea to reach the learning purpose rousing interest of children.

• School Mathematics
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• v.5 no.4
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• pp.555-572
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• 2003

In this study we analyze critically the educational studies on the history of mathematics, and the results of the questionnaires to the mathematics teachers and mathematics teacher educators and interviews with them in order to highlight the problems which ought to be settled for more efficient using the history of mathematics in the mathematics classes. We ought to deepen the understanding of the meaning of mathematical concepts and its essential viewpoints through the historical development of mathematics, going beyond the interest and motivation of learning mathematics. In this respect there are insufficient sides in the results of the educational studies in the history of mathematics and in the recognition of the mathematics teachers about using history of mathematics. And the teachings of the history of mathematics in the mathematics teachers education courses are not sufficient in that they just survey the history of mathematics, and it is the very important task to develop the historic-genetic materials in the school mathematics and study the historic-genetic approach to the mathematics texts.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.120-128
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• 2015

In this paper, Residential roof top photovoltaic system with 9.9 kW design is proposed. The system composed of 200 Watts solar array 33 panels connecting in series 10 strings and parallels 3 strings which have maximum voltage and current are 350 V and 23.8 A. The 10 kW sinusoidal grid-connected inverter with window voltage about 270-350 is selected to convert and transfer DC Power to AC Power at PCC (Point of Common Coupling) of power system following to utility standard. However the impact of fluctuation and uncertainty of weather condition of PV may decrease the voltage stability and voltage collapse of power system. In order to solve this problem the energy storage such 120 V 1200 Ah battery bank and 30 kVAR capacitor are designed for voltage stability control. The other expensed for installing the system such battery charger, cable, accessories and maintenance cost are concerned. The economic analysis by using investment from money loan with interest about 7% and use own money which loss income of deposit about 3% are calculated as 671,844 and 547,044 for PV system with energy storage and non energy storage respectively. The solar energy from PV is about 101,616 Bath per year which evaluated by using the value of $5kWh/m^2/day$ from average peak sun hour (PSH) of the Thailand and 6.96 Bath/kWh of Feed in Tariff Incentive. The payback periods of four scenarios are proposed follow as i) PV system with energy storage and use loan money is 15 years ii) PV system with no energy storage and use loan money is 10 years iii) PV system with energy storage and use deposit money is 9 years iv) PV system with energy storage and use deposit money is 7 years. In addition, the other scenarios of economic analysis such no FIT support and other type of economic analysis such NPV and IRR are proposed in this paper.