• Proceedings of the KSME Conference
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• 2003.11a
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• pp.851-856
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• 2003

A cross-flow fan consists of an impeller, a stabilizer and a rearguider. When it applied for an air conditioner, an evaporator should be added. It relatively makes high dynamic pressure at low speed because a working fluid passes through an impeller blade twice and blades have a forward curved shape. Therefore, the performance of a cross-flow fan is influenced 25% by the impeller, 60% by the rearguider and the stabilizer, 15% by the heat exchanger. At the low flow rate, there are a rapid pressure head reduction, a noise increase and an unsteady flow against a stabilizer and a rearguider. Moreover, the reciprocal relation between the impeller and the flow passage is the important factor for performance improvement of the cross-flow tan because each parameter is independent. The performance characteristics in the cross-flow fan are graphically depicted with various impeller outlet angles and rearguiders.

• Journal of the Korean Society of Visualization
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• v.10 no.1
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• pp.27-33
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• 2012

This paper describes a new design of small-scale horizontal wind blade, called spiral wind turbine blade. Theoretical and numerical approaches on the prediction of aerodynamic performance of the blade have been conducted. A theoretical equation is successfully derived using the angular momentum equation to predict aerodynamic characteristics according to the design shape parameters of spiral blade. To be compared with the theoretical value, a numerical simulation using ANSYS CFX v12.1 is performed on the same design with the theoretical one. Large scale tip vortex is captured and graphically presented in this paper. The TSR-$C_p$ diagram shows a typical parabolic relation in which the maximum efficiency of the blade approximately 25% exists at TSR=2.5. The numerical simulation agrees well with that of the theoretical result except at the low rotational speed region of 0~20 rad/s.

• Communications of Mathematical Education
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• v.23 no.2
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• pp.297-312
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• 2009

We study the process of horizontal and vertical mathematization on the polyhedron problems through the history of mathematics, computer experiments, problem posing, and justifications. In particular, we explore the Hamilton cycle problem, coloring problem, and folding net construction on the Archimedean and Catalan polyhedrons. In this paper, we present our mathematical results on the polyhedron problems, and we also present some unsolved problems that we found. We found that the history of mathematics and mathematical experiments are very useful in such R&E exploration as polyhedron problem posing and solving project.

• Communications of Mathematical Education
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• v.21 no.4
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• pp.663-676
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• 2007

In this paper we study tetrahedron's properties related with intersection of segments and planes using the principle of the lever. We analyze proof method using the principle of the lever, and describe how to prove intersection of segments and planes using the principle of the lever in tetrahedron.

• Journal of Educational Research in Mathematics
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• v.18 no.1
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• pp.81-101
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• 2008

This study points out that the way of teaching varies according to the kinds of figures in explaining the volume and the surface area of solid figures in the seventh grade curriculum. Especially, the study discusses the limitation of the explanation depending on the experimental method using physical objects. Considering the study of Archimedes' research about measuring sphere, we investigate its educational implications and, based on this result, suggest the complementary approach and the considerations for applying to current school mathematics curriculum.

• The KSFM Journal of Fluid Machinery
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• v.7 no.4 s.25
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• pp.7-15
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• 2004

The design point of the cross-flow fan is generally based on the region within low static pressure and high flow rate. It relatively makes high dynamic pressure at low speed because a working fluid passes through an impeller blade twice. However, it has low static pressure efficiency between $30\%$ and $40\%$ because of relative high impact loss. The purpose of this study is to research the reciprocal relation among each parameter. Experiments and numerical analyses are conducted on effects of a stabilizer and a rearguider on performance analysis of a cross-flow fan. Two-dimensional, unsteady governing equations are solved using FVM, PISO algorithm, sliding grid system and standard $k-{\epsilon}$ turbulence model. Experiments are also carried out to estimate the performance of the modeled cross-flow fan. It is clarified that the rearguider of Archimedes type has excellent results for the most part.

• Solar Energy
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• v.11 no.1
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• pp.50-60
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• 1991

A centrifugal pump was selected as a basic study, for it was utilized widely at the industry among various types of pumps. The purpose of this study was to develop the software for design of centrifugal pump. The step of this design was divided into two stages. First, the impeller was designed by the experiences and theory of A.J.Stepanoff, and the head was checked whether the design of impeller was acceptable. Second, the volute chamber was designed by the Archimedes spiral. Then, These procedures of impeller and volute chamber were developed into the software in C-language. Checked the validity of the developed software, the results were consistent with the actual pump produced domestically.

• Journal of the Korean Society of Costume
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• v.66 no.8
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• pp.78-97
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• 2016

The purpose of this study is to develop textile pattern designs by utilizing the prototype of traditional culture extracted from cultural resources in order to establish a specialty strategy for local cultural contents. To achieve this, the study selected the Hyojaemunjado as source of Jeju traditional culture. Jeju's Hyojaemunjado is characterized mainly by the creative and unique formativeness of Jeju's character paintings. Character paintings often contained images related to the characters featured inside characters, or composed stroke with symbolic iconography. The main subjects of Hyojaemunjado were stories that alluded to the Confucian virtues. Therefore, the purpose of this study was to remind people of the real meaning of Shin(truth) by developing textile pattern designs, which borrows the tessellation technique for design, and the dominant characteristic of geometric abstraction. This study used theoretical research and empirical analysis. First, the study did the theatrical research on Hyojaemunjado based on literature and precedent studies, and then analyzed the style of expression and formativeness on the Shin character paintings through real analysis of Jeju's Hyojaemunjado kept in Jeju National University Museum. Second, based on the analysis of the style(three-tier composition) and formativeness of Hyojaemunjado, it analyzed the formativeness of the iconography about Shin, i.e. character types(semi cursive style, square style) drawn according to the symbolic meaning, palace, unknown flower, pheasant, tile fish and constellation. Based on analysis of the iconography, it stylized the motives that became available on the Archimedean tiling of tessellation, and then developed the textile pattern designs by arranging the iconographic motives with Platonic tiling and Semi-tiling. The reason why this study borrowed tessellation was to create various visual effects using the size of angle, symmetry and change and joint with simple figure.

• Journal of Educational Research in Mathematics
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• v.15 no.3
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• pp.335-352
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• 2005

In this paper, we consider a center of gravity of convex polygon which could be an enriched topic for the gifted in mathematics(7th grades) and suggested a case that the gifted experienced a center of gravity. Based on properties of Archimedes' center of mass, we define it as a point which make a polygon be in counterpoised with its area and explain how to find that point through using integral calculus or internal division. Then we consider that the gifted would experience various kinds of mathematical thinking and apply diverse ways of problem solving 3s searching for this topic. As this research, the teacher would be able to conduct the gifted with penetration into center of gravity and to let them participate in advanced learning courses which value ma-thematical thinking while they undergo similar experiences such as mathematicians.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2324-2330
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• 2010

In middle and high school to learn the principles of fluid mechanics to Experiments in space and time constraints and difficulties for the study of the principles of fluid mechanics to the problem is superficial. In this paper, Pascal's principles, Archimedes' Principle, Bernoulli's Theorem, etc. learning about the fluid mechanics and implemented in Web Browser, In connection with flash and HTML, web simulation is to implement. Web Based Instruction program that implemented a comparative analysis became an effect of 15% to industrial total high school students in satisfaction, Interest, Achievement. The fluid mechanics education through engineering design and web design through the actual web server is implemented on the Internet over broadband. Department of Education, this study the fluid mechanics and the Internet will contribute to the development of distance education.