• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.290-295
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• 2001

The surface morphology of oil-lubricated surface for hydraulic piston motor is believed to be extremely effective in contact mechanics. adhesion, friction and wear. In order to describe morphology of various rubbed surface on driving condition, the wear test was carried out under different experimental conditions in oil-lubricated system. And fractal descriptors was applied to rubbed surface of hydraulic driving material with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Morphology of rubbed surface can be effectively obtained by fractal dimensions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.166-170
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• 2003

In this paper, the characteristics of Koch island microstrip patch antenna are investigated by numerical and experimental methods. The Koch patch is fractal shaped antenna which can be characterized by two properties such as space-filling and self-similarity. Due to its space-filling property of fractal structure, the proposed Koch fractal patch antennas are smaller in size than that of conventional square patch antenna. From numerical and experimental results, it is found that as the iteration number and iteration factor of Koch patch increase, its resonance frequency becomes lower than that of conventional patch, thus contributes to antenna size reduction. In particular, when the fractal iteration factor is 1/4, the fractal antenna is 45% smaller in size than that of conventional patch, while maintaining radiation patterns comparable to those of rectangular antenna and cross polarization level is about -20~-14 dB.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.289-297
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• 2000

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface, the harding test was carried out under different experimental conditions in try friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing system These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1329-1336
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• 2000

A new fractal geometry of the traveling wave type cross antenna is newly presented. In the conventional type of the traveling wave antenna, the electrical length of the radiating conductor increases as the order of fractal expansion increases. But, increased length of the current path degrades the performance of the antenna from the various loss mechanism of the traveling wave type antenna. To reduce the antenna performance degradation, the new hybrid fractal antenna, which divides the entire fractal structure into some smaller ones and connects each smaller fractal group with a power divider is presented. The secondly, thirdly and fourthly expanded hybrid fractal cross antennas are fabricated and their performances are examined by measurements. Influences of the fractal order to the antenna performance are examined.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.3
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• pp.1-10
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• 2005

The purpose of this paper is to conduct an experimental measurement and analysis of cities' morphology. Fractal theory that is an effective tool for evaluating self-similarity and complexity of objects was applied. For the comparative analysis of fractailities and computational verification, two totally different cities in Japan were selected. They are Kitakyushu City, which is a big and fully developed city, and Jinguu Machi of which almost all the area is covered with agricultural land use. After converting vector data to raster data within GIS, fractal dimensions of two cases in Kitakyushu City and one case in Jinguu Machi were calculated. The calculation showed that two parts of Kitakyushu City were already fractal. Jinguu Machi, however, was difficult to find fractality. As a conclusion, fractal was proved to be an useful tool to estimate the shape of cities reflecting their internal spatial structure, that is self-similarity and complexity.

• Journal of the Korean association of regional geographers
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• v.16 no.4
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• pp.387-399
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• 2010

This study, using Fractal theory, aims to examine the meaning in the aspect of urban spatial structure by reflecting the characteristics of elements organizing the urban space and at the same time measuring the urban form quantitatively. By calculating Fractal Dimension to Cheongju as a target, it conducted comparison and analysis by dividing building and road which are internal element of a space into the whole city and urbanized area to compare and analyze validity of the theory application and the inside of an actual urban space. For the method of an analysis, it calculated Fractal Dimension by linking a digital map including the property of building and road with GIS program and using box counting. An analysis result showed that the result value of Fractal Dimension by structure and road is all high and similar. It drew a similar result value from the whole Cheongju and the urbanized area as well, but commercial and industrial area showed low result value from the partial viewpoint. However, it is correct to regard these spaces as one space because they are intimately connected with a residential area. From the general viewpoint, it could be said that Cheongju's Fractal Dimension grows in the context of a urbanized area.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.195-201
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• 2014

In this paper, an AccessPoint compact microstrip patch antenna was designed by using L-shaped feeding structure of a Fractal Structure and the compact antenna can be obtained by the rare formed presence of the resonance flow which is called "Crossed-Diagonal". CST's MicroWave5.0 was used for the design. As the operating characteristics of the patch antenna, it showed the characteristic of 1031 [MHz] or 29.4% in the range of 3.202 [GHz] ~ 4.233 [GHz] when an input return loss is less -10 [dB] and VSWR 2:1, also as it is in this paper, we got simulation results such as, gains of the E-plane and H-plane are 8.7 [dBi] and 8.6 [dBi] for this is the single patch, and 3 [dB] beamwidth is $43.9^{\circ}$ at E-plane and $78.7^{\circ}$ at H-plane.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.863-867
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• 2007

In this paper, We have designed miniature microstrip patch antenna based on fractal structure using L-shaped feeding structure for 4G mobile communication applications. Miniature antenna has achieved by the presence of unusual fundamental resonant mode which we call "crossed-diagonal"(CD)current. Using CST Microwave Studio 5.0, patch antenna was designed. The simulated input return loss showed the bandwidth of 1.2647[GHz]($2.944{\sim}4.209GHz$), 35.4% below -10dB. The gain of E, H-plane was achieved 8.3dBi and 8.4dBi respectively. And beamwidth of 3dB in the E, H-plane was $40.6^{\circ}$ and $81.6^{\circ}$, respectively.

• Journal of The Korean Astronomical Society
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• v.49 no.6
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• pp.255-259
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• 2016

We estimate the fractal dimension of the ${\rho}$ Ophiuchus Molecular Cloud Complex, associated with star forming regions. We selected a cube (${\upsilon}$, l, b) database, obtained with J = 1-0 transition lines of $^{12}CO$ and $^{13}CO$ at a resolution of 22" using a multibeam receiver system on the 14-m telescope of the Five College Radio Astronomy Observatory. Using a code developed within IRAF, we identified slice-clouds with two threshold temperatures to estimate the fractal dimension. With threshold temperatures of 2.25 K ($3{\sigma}$) and 3.75 K ($5{\sigma}$), the fractal dimension of the target cloud is estimated to be D = 1.52-1.54, where $P{\propto}A^{D/2}$, which is larger than previous results. We suggest that the sampling rate (spatial resolution) of observed data must be an important parameter when estimating the fractal dimension, and that narrower or wider dispersion around an arbitrary fit line and the intercepts at NP = 100 should be checked whether they relate to firms noise level or characteristic structure of the target cloud. This issue could be investigated by analysing several high resolution databases with different quality (low or moderate sensitivity).

• Imaging Science in Dentistry
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• v.34 no.4
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• pp.179-182
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• 2004

Purpose: The purpose of this study is to examine the effects of X-ray beam angulation on the fractal dimension of trabecular bone structure of human dry mandible using the tile counting method. Materials and Methods: We divided 5 human dry mandibles into an angle and a molar groups depending on the regions and deciding the region of interest (ROI). When contrasted with the ROI, the inferior cortex was appointed to be low and the lines perpendicular to the buccal cortex were appointed to be the standard angle. Direct digital intraoral radiographs were obtained from 9 different projection angles. We analyzed statistically the fractal dimension using the tile counting method. Results: There was a statistically significant difference in the fractal dimension of the regions and the mandibles, but there was no statistically significant difference in the fractal dimension according to the X-ray beam angulation. Conclusion : There is no statistically significant effect of the angle of the projection on the fractal dimension of trabecular bone structure of a human dry mandible according to the tile counting method.