• Communications of Mathematical Education
• /
• v.37 no.3
• /
• pp.419-442
• /
• 2023

This study investigated fifth graders' understanding of variables from a generalized arithmetic and a functional perspectives of early algebra. Specifically, regarding a generalized perspective, we included the property of 1, the commutative property of addition, the associative property of multiplication, and a problem context with indeterminate quantities. Regarding the functional perspective, we covered additive, multiplicative, squaring, and linear relationships. A total of 246 students from 11 schools participated in this study. The results showed that most students could find specific values for variables and understood that equations involving variables could be rewritten using different symbols. However, they struggled to generalize problem situations involving indeterminate quantities to equations with variables. They also tended to think that variables used in representing the property of 1 and the commutative property of addition could only be natural numbers, and about 25% of the students thought that variables were fixed to a single number. Based on these findings, this paper suggests implications for elementary school students' understanding and teaching of variables.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.4
• /
• pp.1013-1024
• /
• 1997

In the traditional object modeling methodologies, the object model can be said as formal since it has been based on rich semantic model. But almost of all methodolgies lack in formality the dyamic model and modeling process. Dynamic model cannot represent exctly the timing constraints and the interaction among the objects, which are very important features in real-time and multimedia system. In this paper, we formalize the synamic moedl and modeling proxess based on object behavior and state. This model defines the object state space using the concepts in algebra stucture and defines the object behavior func-tion. Also this model can formalize object kifecycle and conurrency among the objects usint the temporal logiction. Also this model can frlmaize object lifecycle and conurrency among the objects using the tempral logic and behavior founction. We apply firing rules to behacior function for modeling the dependency of interaction among the objescts.

• Journal of Elementary Mathematics Education in Korea
• /
• v.19 no.3
• /
• pp.251-266
• /
• 2015

The statement, 'Taking more mathematics would result a better mathematics teacher.' sounds plausible. However, it is questionable that how much of taking university level of mathematics such as abstract algebra and real analysis would affect to teach elementary mathematics well. Would a mathematician be a better teacher for elementary students to teach mathematics than who has been prepared to teach elementary mathematics? This paper reports the effects of opportunities to learn tertiary level mathematics and school level mathematics on pre-service primary school teachers' mathematics pedagogical content knowledge. The study analyzed Teacher Education and Development Study in Mathematics 2008 (TEDS-M 2008) database using multiple regression. Prospective primary teachers who have been prepared as generalist were the focus of the study. The results support future elementary teachers might need to have opportunities to revisit school mathematics they are going to teach.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.3
• /
• pp.48-58
• /
• 1999

In this paper, a new parallel computation method, which fully utilize the parallel processors both in mesh generation and FEM calculation for 2D/3D process simulation, is presented. High performance parallel FEM and parallel linear algebra solving technique was showed that excessive computational requirement of memory size and CPU time for the three-dimensional simulation could be treated successively. Our parallelized numerical solver successfully interpreted the transient enhanced diffusion (TED) phenomena of dopant diffusion and irregular shape of R-LOCOS within 15 minutes. Monte Carlo technique requires excessive computational requirement of CPU time. Therefore high performance parallel solving technique were employed to our cascade sputter simulation. The simulation results of Our sputter simulator allowed the calculation time of 520 sec and speedup of 25 using 30 processors. We found the optimized number of ion injection of our MC sputter simulation is 30,000.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.14 no.3
• /
• pp.126-135
• /
• 2011

In this study, the algorithm for priority area of forest fire surveillance was developed to enhance the effectiveness of fire detection. The high priority surveillance area for forest fire detection was defined as the area with not only low value of viewshed analysis of the lookouts and detection cameras but also high fire occurrence probability. To build the priority map, fuzzy function and map algebra were used. The analysis results of Bonghwa-gun, Gyeongbuk Province, showed that the surveillance priority of central and southern area is higher than north area. This algorithm could be used in the allocation of fire prevention resources and selection of suitable point for new fire detection system.

• School Mathematics
• /
• v.9 no.2
• /
• pp.223-240
• /
• 2007

The purpose of this study was to investigate the degree to which the middle school mathematics curriculum matched the item difficulty levels of representative mathematics items. The items used in this study were developed for the National Assessment of Educational Achievement. Ranks for difficulty values of the 60 multiple-choice item were calculated via both Classical Test Theory and Item Response Theory and correlated with the rank order of the mathematics content and cognitive domains sequence. There are six content domains; number and operation, algebra, measurement, figure, pattern and function, and probability and statistics. The cognitive domains include computation, understanding, reasoning and problem-solving. Results suggest a congruence between cognitive domain's sequence and item difficulty levels of items based on that sequence. This finding indicates that the linear or hierarchical assumptions concerning the sequence appears to be reasonable. The characteristics of items that were exceptions to this trend were addressed.

• Communications of Mathematical Education
• /
• v.25 no.1
• /
• pp.119-145
• /
• 2011

We study on the Connected Mathematics Project(CMP), one of the American mathematics education reform projects which have been promoted since the 1990s, so that we can provide some suggestions for the recent research of developing the 2009 Korean Mathematics Curriculum. In this paper, we examine the background of the CMP, the controversies over the textbooks [CMP1 textbooks] developed by CMP[CMP1] implemented from 1991 till 1996, and the curriculum of the CMP[CMP2] revised from CMP1 and carried from 2000 till 2006. Through the literature study, we can see that the CMP2 curriculum has reflected some of those controversies of the CMP1 textbooks by introducing procedures for students' acquiring basic skills, reducing the number of lessons and the contents supposed to be learned in each lesson, putting more stress on algebra and adding data analysis contents more.

• Journal of the Korean Society of Safety
• /
• v.31 no.5
• /
• pp.187-194
• /
• 2016

A single fire event within a fire area can cause multiple initiating events considered in internal events probabilistic safety assessment (PSA). For an example, a fire event in turbine building fire area can cause a loss of the main feed-water and loss of off-site power initiating events. This fire initiating event could result in special plant responses beyond the scope of the internal events PSA model. One approach to address a fire initiating event is to develop a specific fire event tree. However, the development of a specific fire event tree is difficult since the number of fire event trees may be several hundreds or more. Thus, internal fire events PSA model has been generally constructed by modifications of the pre-developed internal events PSA model. New accident sequence logics not covered in the internal events PSA model are separately developed to incorporate them into the fire PSA model. Recently, many fire PSA models have fire induced initiating event fault trees not shown in an internal event PSA model. Up to now, there has been no analytical comparative study on the constructions of fire events PSA model using internal events PSA model with and without fault trees of initiating events. In this study, the changing process of internal events PSA model to fire events PSA model is analytically presented and discussed.

• The KIPS Transactions:PartD
• /
• v.11D no.1
• /
• pp.39-50
• /
• 2004

GML proposed to offer interoperability of geography information is specifying various dynamic object schema for application in the wireless environment. These GML dynamic object schema supports the expression of moving objects that the position and shape change consecutively over time, so practical use of GML is increased in location-based service that provides various application services based on location information of moving objects. In particular, the conventional query languages about GML have been studied with priority given to the integration of geographic information, the support of spatial operations, and etc. However, it lacks the support for moving objects queries. Therefore, in this paper, we propose the moving objects query language that supports moving objects queries for GML documents by extension of XQuery that is standard in query language. Also, data model, algebra operation and various moving objects operators for the proposed query language are designed, and we apply the proposed query language to tornado government organization system to show that the proposed query language can be used effectively in various location-based service.

• Journal of the Korean School Mathematics Society
• /
• v.20 no.2
• /
• pp.119-139
• /
• 2017

The construction in the ancient Greek era had more meanings than a construction in the present education. Based on this fact, this study examines the meaning of the current textbook. In contrast, we have extracted the meaning of the constructions in Euclid Elements. In addition, we have been thinking about what benefits can come up if the meaning of the construction in Euclid Elements was reflected in current education, and suggested a way to exploit that advantage. As results, it was confirmed that the construction in the current textbook was merely a means for introducing and understanding the congruent conditions of the triangle. On the other hand, the construction had four meanings in Euclid Elements; Abstract activities that have been validated by the postulates, a mean of demonstrating the existence of figures and obtaining validity for the introduction of auxiliary lines, refraining from intervening in the argument except for the introduction of auxiliary lines, a mean of dealing with numbers and algebra. Finally we discussed the advantages of using the constructions as a means of ensuring the validity of the introduction of the auxiliary line to the argument. And we proposed a viewpoint of construction by intervention of virtual tools for auxiliary lines which can not be constructed with Euclid tool.