• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1629-1643
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• 2016

Let R be a ring with identity, X be the set of all nonzero, nonunits of R and G be the group of all units of R. A ring R is called unit-duo ring if $[x]_{\ell}=[x]_r$ for all $x{\in}X$ where $[x]_{\ell}=\{ux{\mid}u{\in}G\}$ (resp. $[x]_r=\{xu{\mid}u{\in}G\}$) which are equivalence classes on X. It is shown that for a semisimple unit-duo ring R (for example, a strongly regular ring), there exist a finite number of equivalence classes on X if and only if R is artinian. By considering the zero divisor graph (denoted ${\tilde{\Gamma}}(R)$) determined by equivalence classes of zero divisors of a unit-duo ring R, it is shown that for a unit-duo ring R such that ${\tilde{\Gamma}}(R)$ is a finite graph, R is local if and only if diam(${\tilde{\Gamma}}(R)$) = 2.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2615-2626
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• 1998

In this paper, we propose a new interconnection network called RFM graph, whichis the merger of the directed rotator and Faber-Moore graph, and analyze fault tolerance, routing algorithm node disjoint cycles and broadcasting algorithm. We also describe methods to embed star graph, 2 dimesional torus and bubblesort graph into RFM graph with unit expasion and dilation 2.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.203-206
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• 2000

In the multi-purpose lathe, the design of tilting turret slide system has an important and critical role to enhance the accuracy of the machining process. Tilting turret unit is traveled by 3-axis slide systems. There is a need to design this part very carefully. In this research, the 3-axis slide system with tilting turret unit is researched with two approaches; The first is that 3-axis slide system is modeled and simulated usig ADAMS software. The dynamic behavior of this system is visualized by data graphs and dynamic animations. The first step of virtual prototype which makes it possible to design economically and effectively is developed.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.556-556
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• 2000

In the multi-purpose lathe, the design of tilting turret slide system has an important and critical role to enhance the accuracy of the machining process. Tilting turret unit is traveled by 3-axis slide systems. There is a need to design this part very carefully. In this research, the 3-axis slide system with tilting turret unit is researched with two approaches; The first is that 3-axis slide system is modeled and simulated using ADAMS software. The dynamic behavior of this system is visualized by data graphs and dynamic animations. The second is that the slide system is analyzed with the aspect of stress distribution. The slide system is modeled and displayed by PATRAN and analyzed by NASTRAN. The analysis of strain and stress distribution in the each node is prompted and visualized in the computer. The first step of virtual prototype which makes it possible to design economically and effectively is developed.

• Honam Mathematical Journal
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• v.44 no.4
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• pp.594-617
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• 2022

In this study, firstly Smarandache ruled surfaces whose base curves are Smarandache curves derived from Frenet vectors of the curve, and whose direction vectors are unit vectors plotting Smarandache curves, are created. Then, the Gaussian and mean curvatures of the obtained ruled surfaces are calculated separately, and the conditions to be developable or minimal for the surfaces are given. Finally, the examples are given for each surface and the graphs of these surfaces are drawn.

• Journal of the Korean earth science society
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• v.30 no.4
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• pp.513-526
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• 2009

It has long been that the unit of oceanic salinity changed from permil (%o) to other unit. However, the middle-and high- school textbooks of science and earth science have still used %o as salinity unit that was defined a long time ago. The objectives of this study are to briefly discuss about the historical development of change in salinity unit and measurement techniques, to present differences between the salinity units of psu (practical salinity unit) and %o, and to address the need and validity for the correction of salinity unit in the textbooks. Twenty-seven kinds of textbooks based on the 7th National Curriculum were analyzed to investigate the expression of salinity unit and the definition of salinity. The results were compared with the usage of salinity units in the articles published in Journal of Korean Society of Oceanography from 1967 to 2008. The percentages by the use of %o were 96.3% in the text and 83.8% in the graphs or tables of the textbooks. By contrast, the scientific papers began to use psu from 1994 and then %o has seldom been used since 2004.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.825-828
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• 2005

In this paper, we propose a new nonvolatile unit memory cell and proposal peripheral circuit using the polymer material. Memory that relies on bistable behavior- having tow states associated with different resistances at the same applied voltage - has attracted much interest because of its nonvolatile properties. Such memory may also have other merits, including simplicity of structure and manufacturing, and the small size of memory cells. We have plotted the load line graphs for the use of a polymer memory character, hence we have designed in the band-gap reference shape of a write/erase drive, and then designed in the 2-stage differential amplifier shape of a sense amplifier in the consideration of a low current characteristic of a polymer memory cell. The simulation result shows that is has high gain about 80dB by sensing the very small current.

• Research in Mathematical Education
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• v.22 no.2
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• pp.83-97
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• 2019

Science, Technology, Engineering, and Mathematics (STEM) education has been at the forefront of K-12 curricula in the technology-rich 21st century, with emphasis on how these fields reinforce each other in preparing students for a dynamic future. However, there is a need for greater attention to STEM education research in the mathematics education community, in particular to pedagogical approaches that facilitate integrating the mathematics component of STEM education. Toward this end, the authors report the outcomes of a Project-based Learning (PBL) unit in which upper elementary students integrated STEM elements by researching, crafting, testing, and evaluating kites they created by applying scientific knowledge of aerodynamics and mathematical knowledge of polygons, surface area, graphs, and data analysis. This unit, which the authors developed, implemented, and assessed, demonstrates how STEM subjects and in particular mathematics can be effectively integrated in upper elementary school classrooms through PBL.

• Journal of the Korean earth science society
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• v.29 no.6
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• pp.487-494
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• 2008

The purpose of this study was to investigate the effects of MBL experiment instruction on the 7th graders' scientific inquiry skills and graph construction and interpretation ability in the unit "Elements and movement of sea water". Results are as follows: First, this study analyzed the influence on students' scientific inquiry skill after having six MBL instructional classes. The result showed a significant difference in the scientific inquiry skills between the experimental group and the control group, which implies that the instruction using MBL was an effective way to improve students' scientific inquiry skills. Second, this study also analyzed the influence on students' abilities to construct and interpret graphs. The result did not show any significant differences between the experimental group and the control group in the ability to construct graphs. But it showed significant differences in the ability to interpretgraphs, which means that instruction using MBL was an effective way to improve students' ability to interpret graphs.

• Journal of the Korean Chemical Society
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• v.60 no.5
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• pp.327-341
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• 2016

This study explores the effective visual resources in the “regularity in chemical reactions” unit of ninth grade science textbooks (2009 revised version). The frequency and role of visual resources were initially examined, and the students’ perceptions of visual resources were investigated. The results of the analysis represented the learning material presentation (68%), motivational categories (14%), guide to inquiry procedures (9%), and inquiry results and summaries (8%). According to the investigation of the students’ perceptions of visual resources, the most effective visual resource for motivation is a photograph depicting physical and chemical changes, such as in bread baking and the most effective for learning material presentations in mass conservation, definite proportion, and stoichiometric concept units were a cartoon, graph, and formula representing stoichiometric phenomena, respectively. The most effective resource for guide to inquiry (experimental) procedures were photographs of both instruments and sequential experiment processes; and in the inquiry results and summary category, incomplete tables and graphs for students to work on themselves. The aims of this research are to increase the usefulness of visual resources in the teaching-learning activity and provide informative supplements for the development and improvement of visual resources, according to the students’ perceptions.