• School Mathematics
• /
• v.11 no.1
• /
• pp.131-145
• /
• 2009

This research was designed to investigate the possibility to teach function concept and graph representation of functions in explicit manner toward at elementary level. Eight class-hours instruction was given to four Grade 5(age 11) students, and dynamic geometry software GSP was partially used in the class. Results indicate that the students could conceptualize the function relation, interpret linear function graphs, recognize the meaning of their slopes, and discuss the relationships among linear graphs and real life situation. Results also indicate that GSP helped students to recognize the relation between dots and the linear graph clearly and that GSP-line graph did decisive role for children to understand the meaning of graph representation of function.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.6
• /
• pp.431-436
• /
• 2002

The interior sound pressure level of the Korean high-speed train(KHST) is predicted by geometrical acoustic method. For the Purpose of assuring the prediction of Interior noise of KHST by the geometrical acoustic scheme, calculated sound level values of the Korean train express(KTX) by Identical geometrical method are compared with measured values of KTX prototype vehicle by experiment. Contribution of individual sound source of KHST vehicle Into the interior response positions is calculated and sound sources are classified in influential order. Hence, it is reasonable approach to reduce sound power of most contributing noise source first. Sensitivity of the interior response position's sound pressure level (SPL) with respect to train wall sections' transmission loss are carried on and acoustically sensitive spot is identified, for example window area for passenger cabin case. Those contribution and sensitivity analysis results are suggested to design quieter train efficiently.

• Journal for History of Mathematics
• /
• v.20 no.1
• /
• pp.33-44
• /
• 2007

This paper examines a historical case- the French Revolution- of conceptual change in mathematics. The case that is a space of possibility gave birth to a new community of mathematical practitioners. Carnot and Monge shared the particular conceptions of the problems, aims, and methods of a field and contributed to found Ecole Polytechnique. I intend to show how Carnot's and Monge's mathematical endeavours responded to social, political and technological developments in French society.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.6
• /
• pp.1259-1265
• /
• 1997

We investigate depth measurement error of a range finder based on triangulation method. Geometric analysis resulted in intuitive understanding of the error sensitivity. We show that the depth error is propostional to the distance between the object andthe camera. The measurement value has the highest accuracy when the line connecting the focal point of the camera and the object is perpendicular to the line joining the object and the light source of herange finder. Also we analyze the error using a perturbation method and verify that the results are identical through an experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.237-240
• /
• 1997

The casing oscillator is a construction equipment to clamp, oscillate and push a casing for foundation work. In case that the casing oscillator is operated on the slant ground, if another construction heavy equipment is not used, it is impossible to insert the casing in ground using only casing oscillator. So in this paper, we present the new casing oscillator that need not to level the ground for work of casing insertion. This mechanism can execute 4 DOF motion by actuating 5 single - rod hydraulic cylinders. The forward kinematics analysis of the casrng oscillator by tetrahedron geometry is performed so predict workspace, direction and poison of casing oscillatoer.

• Journal of Korean Society for Geospatial Information Science
• /
• v.5 no.2 s.10
• /
• pp.55-63
• /
• 1997

Precision digital data capture and spatial analysis system to cultural properties play important roles in preserving the existing properties. This study presents the acquisition oi digital data in geometrical context and spatial analysis for more effective management to cultural properties. Established in the same coordinates system, Precision 3D measurements and image analysis were peformed. In addition, geometrical analysis, and 3D monitoring to Songsanri Royals Tombs in Gongju were carried out in generating basedata for conservation plan.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.711-715
• /
• 1996

This paper describes an automated computer-aided engineering (CAE) system for micromachines whose size range 10 to 10$^3$${\mu}{\textrm}{m}$. An automatic finite element mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with one of commercial finite clement (FE) analysis codes, MARC, and one of commercial solid modelers, Designbase. The system allows a geometry model of concern to be a automatically converted to different FE models, depending on physical phenomena to be analyzed, i.e. electrostatic analysis, stress analysis, modal analysis and so on. The FE analysis models are then exported to the FE analysis code, and then analyses are performed. This system is successfully applied to an electrostatic micro actuator.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.6
• /
• pp.709-715
• /
• 1999

To optimize a heating and cooling system, we need an exact solution lot radiant heat transfer in any form of room or building. This paper describes the solution method of view factor by the area weighted average and graphical method to calculate the radiant heat exchange or daylighting level in any form of room or building. This study shows that the area weighted average and graphical methods have many points of merits(calculation speed, correctness and calculation capability in an arbitrary form of room shapes etc.) compared with existing methods

• School Mathematics
• /
• v.14 no.3
• /
• pp.331-355
• /
• 2012

All the method used in teaching the ellipse was to have students draw the points which have the same sum of distances from the two points so that they can confirm the shapes of the ellipse before showing them the definition of ellipse. In this process, students would not get an opportunity to think or make the definition of ellipse for themselves. This deductive way can hinder students from having clear understanding of why such definition was made. This paper introduces a method of defining the ellipse based on the similarity between a circle and an ellipse, leading into the equation. This method is possible by introducing Analytic Geometry taught in current school mathematics and Transformation Geometry. By doing so, this paper will discuss a fundamental understanding about the ellipse and the feature of the ellipse expandable by intuition. Furthermore this paper will also show various advantages which can be given by defining the ellipse in Transformation Geometry.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.4
• /
• pp.199-204
• /
• 2021

In this study, an isogoemetric analysis (IGA) method that uses NURBS (Non-Uniform Rational B-Spline) basis functions in computer-aided design (CAD) systems is employed to account for the geometric exactness of curved electrodes constituting an electro-adhesive pad in electrostatic problems. The IGA is advantageous for obtaining precise normal vectors when computing the electro-adhesive forces on curved surfaces. By performing parametric studies using numerical examples, we demonstrate the superior performance of the curved electrodes, which is attributed to the increase in the normal component of the electro-adhesive forces. In addition, concave curved electrodes exhibit better performance than their convex counterparts.