• Proceedings of the KSME Conference
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• 2000.04b
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• pp.290-295
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• 2000

An experimental study was carried out in a cavity with upper channel and square heat surface by visualization equipment with Mach-Zehnder interferometer and laser apparatus. The visualization system consists of 2-dimensional sheet light by Argon-Ion Laser with cylindrical lens and flow picture recording system. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system(CACTUS'2000). Obtained result showed various flow patterns. Severe unsteady flow fluctuation within the cavity are remarkable and sheared mixing layer phenomena are also found at the region where inlet flow is collided with the counter-clockwise rotating main primary vortex. Photographs of Mach-Zehnder are also compared in terms of constant heat flux.

• Journal of the Korean Society of Visualization
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• v.5 no.2
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• pp.20-25
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• 2007

The geometry of a commercial passenger airplane is realized based on a Boeing 747-400 model through the photographic scanning and reverse engineering. The each element consisting of the plane such as fuselage, wing, vertical fin, stabilizer and engines, is individually generated and then the whole body is assembled by the photomodeler. The maximum error in the realized airplane is about 1.4% comparing with the real one. The three-dimensional inviscid steady compressible governing equations are solved in the unstructured tetrahedron grid system, and in a finite volume method using STAR-CD when the airplane flies at the cruise condition. The pressure distribution on the surface and the wing-tip vortices are visualized, and in addition to the aerodynamics coefficients, lift and drag are estimated.

• Solar Energy
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• v.20 no.4
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• pp.53-60
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• 2000

An experimental study was carried out in a cavity with upper channel and square heat surface by visualization equipment with Mach-Zehnder interferometer and laser apparatus. The visualization system consists of 2-dimensional sheet light by Argon-Ion Laser with cylindrical lens and flow picture recording system. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system(CACTUS'2000). Obtained result showed various flow patterns. Severe unsteady flow fluctuation within the cavity are remarkable and sheared mixing layer phenomena are also found at the region where inlet flow is collided with the counter-clockwise rotating main primary vortex. Photographs of Mach-Zehnder are also compared in terms of constant heat flux.

• Journal of Educational Research in Mathematics
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• v.19 no.1
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• pp.143-161
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• 2009

This study was designed to gain insights into students' visualization process in geometric problem solving. The visualization model for analysing visual process for geometric problem solving was developed on the base of Duval's study. The subjects of this research are two Grade 9 students and six Grade 10 students. They were given 2D-geometric problems. Their written solutions were analyzed problem is research depicted characteristics of process of visualization of individually. The findings on the students' geometric problem solving process are as follows: In geometric problem solving, visualization provided a significant insight by improving the students' figural apprehension. In particular, the discoursive apprehension and the operative apprehension contributed to recognize relation between the constituent of figures and grasp structure of figure.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.67-70
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• 2003

Hard disk drives (HDD) in computer are used extensively as data storage capacity. The trend in the computer industry to produce smaller disk drives rotating at higher speeds requires an improved understanding of fluid motion in the space between disks. Laser sheet and digital camera was used for 2-dimensional visualization of the unsteady flow between the center pair of two co-rotating disks in air with a cylindrical enclosure (or shroud). Geometric parameters are gap height (H) between disks, and gap distance (G) between disk tip and shroud. The lobe-structured boundary between inner region and outer region was detected by inserted particles, and the number of dominant vortices was determined clearly It is found from flow visualization that the number of vortex cells can be correlated with Reynolds number based on H which is defined as $Re_H={\Omega}RH/v$ ranging from $3.18\times10^3\;to\;1.43\times10^4$, and decreases as the disk speed increases. The lobe pattern by vortex cells is changed to a circular pattern for the wide gap than narrow one.

• Spatial Information Research
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• v.15 no.1
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• pp.35-52
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• 2007

Three-dimensional GIS, which provides spatial information through expression techniques of virtual reality close to the real world and the web, is one of the fields that attract a new attention. In particular, Open GIS Consortium(OGC) announced a topological relationship specification of spatial object which supports interoperability while interest in interoperability of spatial data is increasing. However, this specification is limited to two-dimensional spatial object. So this research established a topological relationship of three-dimensional spatial object in order to improve urban landscape and provide a foundation to use GIS. Based on this, this study proposes ways to visualize landscape information which is appropriate for new town's circumstances. It can be concluded that this research has a bigger meaning since it established a base of sharing information about realistic urban landscape that can be accessed regardless of place and time.

• Education of Primary School Mathematics
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• v.17 no.2
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• pp.159-171
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• 2014

Spatial ability has been valued as one component of intelligence and as an talented domain. And it is associated with the achievements in science, technology, engineering, and mathematics (STEM) disciplines. So, the instrument for measuring spatial ability is very important. The purpose of this study is to develop Spatial Visualization Tests for Elementary School Children and examine internal consistency reliability evidence and construct validity evidence on confirmatory factor analysis of that instrument. For this purpose, 'The Spatial Visualization Tests for Elementary School Children was administered to 1482 Korean elementary school students. As a result, this study show that internal consistency reliability evidence using Cronbach' alpha showed item consistency and construct validity evidence from confirmatory factor analysis in the Spatial Visualization Tests for Elementary School Children. And also, this study show ed that item difficulty and item discrimination of the Spatial Visualization Tests for Elementary School Children were within an acceptable range.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1661-1665
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• 2004

Hard disk drives (HDD) in computer are used extensively as data storage capacity. The trend in the computer industry to produce smaller disk drives rotating at higher speeds requires an improved understanding of fluid motion in the space between disks. Laser sheet and digital camera was used for 2-dimensional visualization of the unsteady flow between co-rotating disks in air with a cylindrical enclosure (or shroud). Geometric parameters are gap height (H) between disks, and gap distance (G) between disk tip and shroud. The lobe-structured boundary between inner region and outer region was detected by inserted particles, and the number of dominant vortices was determined clearly It is found from flow visualization that the number of vortex cells can be correlated with Reynolds number based on H which is defined as $Re_H={\Omega}RH/v$ ranging from $7.96{\times}10^2$ to $1.43{\times}10^4$, and decreases as the disk speed increases. The lobe pattern by vortex cells is changed to a circular pattern for the wide gap than narrow one.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.47-50
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• 2003

The wind flow and pollutant dispersion over a two-dimensional sinusoidal hilly obstacle with slope (the ratio of height to half width) of 0.7 have been investigated experimentally and numerically. Flow over a single sinusoidal hill model was visualized in a subsonic wind tunnel. The mean velocity profiles, turbulence statistics, and pollutant concentration distribution were measured at the Reynolds number based on the obstacle height (H=40mm) oft $2.6\times10^4$. Experimental results for flow over a flat ground were agreed with the theoretical and numerical results. When a pollutant source is located behind the hilly terrain, the pollutant dispersion appeared even in the upstream region due to recirculation flow.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.259-260
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• 1998

In this paper, we present a 3D visualization method of medical image on PC. Using morphological method, we used to segment 2D medical images (X-ray CT, MRI). Presented method is treating in some detail two operations : dilation and erosion. Also known as an isosurface, using a constant density surface make a target organ in 3D. In the whole procedure for visualization. The medical images are implemented by using Visual C++ 5.0 in activeX and IDL(interactive data language) under PC environment.