• Tribology and Lubricants
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• v.33 no.6
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• pp.303-308
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• 2017

Most automobile tire companies have not yet considered the geometric information of a road at the design stage of a tire because the topographical characterization of a road surface is very difficult owing to its vastness and randomness. A road surface shows variable surface roughness values according to magnification, and thus, the contact force between the road and tire significantly fluctuates with respect to the scale. In this study, we make an attempt to define a representative value for surface topographical information at multi-scale levels. To represent surface topography, we use a statistical method called power spectral density (PSD). We use the fast Fourier transform (FFT) and PSD to analyze the height profiles of a random surface. The FFT and PSD of a surface help in obtaining a fractal dimension, which is a representative value of surface topography at all length scales. We develop three surfaces with different fractal dimensions. We use finite element analysis (FEA) to observe the contact forces between a tire and the road surfaces with three different fractal dimensions. The results from FEA reveal that an increase in the fractal dimension decreases the contact length between the tire and road surfaces. On the contrary, the average contact force increases. This result indicates that designing and manufacturing a tire considering the fractal dimension of a road makes safe driving possible, owing to the improvement in service life and braking performance of the tire.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.125-129
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• 2014

In this paper, design and fabrication of the GPS receiving antenna using Hilbert curve fractal structure was proposed. The size of the antenna was miniaturized by transforming dipole structure into monopole structure because its size increases if Hilbert curve fractal dipole structure is used. To use a Hilbert curve structure, the current directions of the radiator were made oppositely each other. The size of the antenna is $10{\times}10{\times}0.8[mm]$, the line width is 0.25[mm]. The resonant frequency is 1.58[GHz] and its range is 1.52[GHz] ~ 1.65[GHz]. Frequency bandwidth is 130[MHz]. Antenna maximum gain is 3.09[dBi].

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1008-1014
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• 2011

In this paper, multi-band fractal microstrip patch antenna which is possible for WLAN band and WiMax band is designed and made. For multi-resonance of developed antenna, resonance frequency, impedance matching, polarity and reflection pattern can mad perfectly, then to make satisfied multi-independent frequency three kind of half circle fractal patch is inserted. In the situation continuously happening half circle in designed structure, antennas one of half-circle band is shown.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.55-58
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• 2008

In this paper, the new type wiggly directional coupler which uses the fractal coupled shape in coupled sections is presented. A commercial software has been used to analyze this new structure and the simulation results are compared to those of the conventional wiggly directional coupler. To verify the simulation results, the new type wiggly directional coupler was fabricated with the center frequency of 15GHz. The measurement results shows that the coupling of new structure proposed in this paper is more than that of conventional wiggly coupler. The results in this paper also show that the fractal shape coupled lines in wiggling sections can improve the coupling characteristics in wiggly directional coupler.

• International Journal of CAD/CAM
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• v.8 no.1
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• pp.37-40
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• 2009

Based on the study of Digital Elevation Simplification Model and fractal theory, this paper put forward a new method to simulate complex terrain. That use simplified DEM data to construct terrain frame based on the quad tree at first, and then use fractal to generate the details of every node of the tree. In the process of construction, the LOD theory is used to simplify the terrain and get its typical data. According to the change of view position and direction, the paper gives a new way to judge the visibility of the surface patch. Experimental results show that this algorithm is simple, efficient and supports the real time dynamic simulation of terrain model.

• Proceedings of the Korea Society of Design Studies Conference
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• 2003.05a
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• pp.160.2-171
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• 2003

• 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.

• Korean Institute of Interior Design Journal
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• v.23 no.1
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• pp.88-95
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• 2014

This study intended arousal of other viewpoints that deal with and understand spaces and shapes, by describing the concept of 'dimensions' into visual patterns. Above all, the core concept of spatial dimensions was defined as 'expandability'. Then, first, the 'golden ratio', 'Fibonacci sequence', and 'fractal theory' were defined as elements of each dimension by stage. Second, a 'unit cell' of one dimension as 'minimum unit particles' was set. Next, Fibonacci sequence was set as an extended concept into two dimensions. Expansion into three dimensions was applied to the concept of 'self-similarity repetition' of 'Fractal'. In 'fractal dimension', the concept of 'regularity of irregularity' was set as a core attribute. Plus, Platonic solids were applied as a background concept of the setting of the 'unit cell' from the viewpoint of 'minimum unit particles'. Third, while 'characteristic patterns' which are shown in the courses of 'expansion' of each dimension were embodied for the visual expression forms of dimensions, expansion forms of dimensions are based on the premise of volume, directional nature, and concept of axes. Expressed shapes of each dimension are shown into visually diverse patterns and unexpected formative aspects, along with the expression of relative blank spaces originated from dualism. On the basis of these results, the 'unit cell' that is set as a concept of theoretical factor can be defined as a minimum factor of a basic algorism caused by other purpose. In here, by applying diverse pattern types, the fact that meaning spaces, shapes, and dimensions can be extracted was suggested.

• Proceedings of the Korea Society of Design Studies Conference
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• 1998.04a
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• pp.18-19
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• 1998

• Advances in Computational Design
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• v.1 no.1
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• pp.79-86
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• 2016

In this study, the three different meta-heuristics namely the Grey Wolf Optimizer (GWO), Stochastic Fractal Search (SFS), and Adaptive Differential Evolution with Optional External Archive (JADE) algorithms are examined. This study considers optimization of the planer frame to minimize its weight subjected to the strength and displacement constraints as per the American Institute of Steel and Construction - Load and Resistance Factor Design (AISC-LRFD). The GWO algorithm is associated with grey wolves' activities in the social hierarchy. The SFS algorithm works on the natural phenomenon of growth. JADE on the other hand is a powerful self-adaptive version of a differential evolution algorithm. A one-bay ten-story planar steel frame problem is examined in the present work to investigate the design ability of the proposed algorithms. The frame design is produced by optimizing the W-shaped cross sections of beam and column members as per AISC-LRFD standard steel sections. The results of the algorithms are compared. In addition, these results are also mapped with other state-of-art algorithms.