• Journal of Navigation and Port Research
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• v.35 no.1
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• pp.51-56
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• 2011

In this paper, we presents an algorithm which restores lost data or increases resolution of a DTM(Digital terrain model) using fractal theory. Terrain information(fractal dimension and standard deviation) around the patch to be restored is extracted and then with this information and original data, the elevations of cells are interpolated using the random midpoint displacement method. The results of the proposed algorithm are compared with those of the bilinear and bicubic methods on a fractal terrain map.

• Tunnel and Underground Space
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• v.22 no.3
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• pp.196-204
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• 2012

Quantification of roughness plays an important role in modeling strength deformability and fluid flow behaviors of rock joints. A procedure was suggested to simulate joint roughness, and characteristics of the roughness was investigated in this study. Stationary fractional Brownian profiles with known input values of the fractal parameter and other profile properties were generated based on random midpoint displacement method. Also, a procedure to simulate three dimensional roughness surface was suggested using the random midpoint displacement method. Selected statistical roughness parameters were calculated for the generated self-affine profiles to investigate the attribute of roughness. Obtained results show that statistical parameters applied in this study were able to consider correlation structure and amplitude of the profiles. However, effect of data density should be tackled to use statistical parameters for roughness quantification.

• Tunnel and Underground Space
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• v.26 no.6
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• pp.516-523
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• 2016

Roughness of a joint surface is one of the most important parameters that affects the mechanical and hydraulic behavior of rock mass. Therefore, various studies on making constitutive model and/or roughness quantification have been conducted in experimental and empirical manners. Advances in recent 3D printing technology can be utilized to generate a joint surface with a specific roughness. In this study, a reliable technique to generate a rough joint surface was introduced and its quantitative assessment was made. Random midpoint displacement method was applied to generate a joint surface and the distribution of $Z_2$ was investigated to assess its roughness. As a result, a certain roughness can be embodied by controlling input parameters and furthermore it was able to generate a joint surface with specific roughness anisotropy.

• Journal of the Korea Computer Graphics Society
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• v.6 no.3
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• pp.17-23
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• 2000

Recently, as it is growing concern about Non-Photo-Realistic Rendering, several researchers are studying to simulate conventional artistic expressions such as pen-and-ink, watercolor and impressionism techniques. In this paper, we describe a mosaic technique using color paper tore by hands. We will also try to represent real paper by using random midpoint displacement method (RMD) to express a shape of paper tore by hands without using cutters or scissors. The Perlin's noise function is used to express texture of paper.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1080-1085
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• 2003

The flow of electrical current through a microscopic actual contact spot between two conductors is influenced by the flow through adjacent contact spots. A smoothed version of this interaction effect is developed and used to predict the contact resistance when the statistical size and spatial distribution of contact spots is known. To illustrate the use of the method, an idealized fractal rough surface is defined using the random midpoint displacement algorithm and the size distribution of contact spots is assumed to be given by the intersection of this surface with a constant height plane. With these assumptions, it is shown that including finer scale detail in the fractal surface, equivalent to reducing the sampling length in the measurement of the surface, causes the predicted resistance to approach the perfect contact limit.

• Journal of the Korea Computer Industry Society
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• v.2 no.3
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• pp.297-308
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• 2001

We propose an algorithm which can reconstruct the 3D information from geographical information. The conventional techniques, the triangular patches and the Random Fractal Midpoint Displacement (RFMD) method, etc., have often been used to reconstruct natural images. While the RFMD method using Gaussian distribution obtains good results for the symmetric images, it is not reliable on asymmetric images immanent in the nature. Our proposed algorithm employs neural networks for the RFMD method to present the asymmetrical images. By using a neural network for reconstructing the 3D images, we can utilize statistical characteristics of irregular data. We show that our algorithm has a better performance than others by the point of view on the similarity evaluation. And, it seems that our method is more efficient for the mountainous topography which is more rough and irregular.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.344-355
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• 2008

In this paper, we are dealing with the problems of performance evaluation of Differentiated Services(DiffServ) networks. For successful performance evaluation, the ability to accurately represent "real" traffic on the network by suitable traffic models is an essential ingredient. Many research results on the nature of real traffic measurements demonstrated LRD(long-range dependence) property for the Internet traffic including Web, TELNET, and P2P traffic. The LRD can be effectively represented by self-similarity. In this paper, we design and implement self-similar traffic generator using the aggregated On/Off source model, based on the analysis of the On-Off source model, FFT-FGN(Fast Fourier Transform-Fractional Gaussian Noise) model, and RMD(Random Midpoint Displacement) model. We confirmed the self-similarity of our generated traffic by checking the packet inter-arrival time of TCPdump data. Further we applied the implemented traffic generator to the performance evaluation of DiffServ networks and observed the effect of performance to the a value of the On/Off model, and performance of EF/BE class traffic by CBQ.