• Journal of the Korean Society of Costume
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• v.62 no.6
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• pp.200-217
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• 2012

The purpose of this research is to examine the specificity of grids to define the characteristics of clothes styles in the Joseon Dynasty period. The significance of examining of the specificity of grids is to find out arbitrary types of the features of grids involved in structuring the Jeogori in the Joseon Dynasty period one by one. The Visual Linguistic Theory was introduced as a methodological tool to exquisitely analyze the characteristics of grids in deep structures of Jeogori in the Joseon Dynasty period. This theory strives to examine sample distribution, the distribution of samples by quality and the distribution of the types of ploidy features. Through the examination, the results are as follows. The grid systems of the Jeogori consisted of diverse proportion systems reaching 86 cases, that is, sequence systems composed of multi-functional, multi-combined bodies. Most ornamental grids had feature angles distributed in a range of $2-20^{\circ}$ that showed a common preference for low sloped diagonal lines or small curvature. Although the preference for certain feature angles were prominent, the feature angles that were used were generally distributed evenly among diverse feature angles to show the characteristics of separation. Therefore, Jeogori makers in the Joseon Dynasty period can be considered as having experimented with many proportion systems to show their aesthetics. In conclusion, based on the results of the examination of feature distributions and related methods to allocate ploidy features, O-type accounted for 66% and thus it was identified that the Jeogori was characterized by O-type. Therefore, it was identified that the characteristic of the Jeogori in the Joseon Dynasty period consisted of O-type fractal structures which are formative structures unique to our nation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1852-1865
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• 2017

The vibration of the structures with restrained motion has long been observed in various engineering fields. When the motion of vibrating structure is restrained due to the adjacent objects, the frequencies and the mode shapes of the structure change and its vibration characteristics becomes unpredictable, in general. Although the importance of the study on this type of vibration model increases in many engineering areas, most studies conducted so far are limited to the theoretical study on dynamic responses of the structure with stops, including some experimental works. Specially, the study on the nonlinear phenomena due to the impact between the structure and the stops have been mainly performed theoretically. In the paper, both numerical analyses and experiments are conducted to study the chaotic vibration characteristics of the nonlinear motion and the dynamic response of a cantilevered beam which has restrained motion at the free end by the stops. Results are presented for various magnetic forces and gaps between the beam and stops. The conclusions are as follows : Firstly, Numerical simulation results have a good agreement with experimental ones. Secondly, the effect of higher modes of beams are increased with increasing magnitude of exciting force, and displacement and velocity curves become more complicated shapes. Thirdly, nonlinear characteristics tend to appear greatly with increasing magnitude of exciting force, and fractal dimension is increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.504-510
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• 2002

Recently, thin film capacitors of high dielectric constant and low leakage current are applied to integrated devices. In this study, (Ba, Sr)$TiO_3$ (BST) thin films for low cost were prepared by Sol-Gel method. BST solution was spin-coated on Pt/$SiO_2$/Si substrate at 4,000 rpm for 10 seconds. Coating process was repeated 3 times and then sintered at $700^{\circ}C$ for 30 minutes. Structural and electrical characteristics of each specimen were analyzed by TG-DTA, SEM, fractal phenomenon, voltage-current and dielectric factor. Thickness of BST ceramics thin films are about 2,600~2,800 ${\AA}$ at depositing 3 times. Dielectric constant of thin films was decreased in 1 kHz~1 MHz. Dielectric constant and loss to frequency were 250 and 0.02 in $(Ba_{0.7}Sr_{0.3})TiO_3$ (BST3). Leakage current of BST3 was $10^{-9}\sim10^{-11}$/ A under 3 V.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.997-1009
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• 1999

Silica particle formation and growth process including chemical reaction, coagulation and sintering was studied in a counterflow diffusion flame burner. The counterflow geometry provides a one dimensional flow field, along the stagnation point streamline, which greatly simplifies interpretation of the particle growth characteristics. $SiCl_4$ has been used as the source of silicon in hydrogen/oxygen/argon flames. The temperature profiles obtained by calculation showed a good agreement with experiment data. Using one and two dimensional sectional method, aerosol dynamics equation in a flame was solved, and these two results were compared. The two dimensional section method can consider sintering effect and growth of primary particle during synthesis, thus it showed evolution of morphology of non-spherical particles (aggregates) using surface fractal dimension. The effects of flame temperature and chemical loading on particle dynamics were studied. Geometric mean diameter based on surface area and total number concentration followed the trend of experiment results, especially, the change of diameters showed the sintering effect in high temperature environment.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.909-915
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• 2008

Recently, the interests in the development and application of unmaned robots are increasing in various fields including surveillance and reconnaissance, planet exploration, and disaster relief. Unmaned robots are usually controlled from distance using radio communications but they should be equipped with an autonomous travelling function to cope with unexpected terrains and obstacles. This means that they should be able to evaluate terrain's characteristics quantitatively using mounted sensors so as to traverse harsh natural terrains autonomously. For this purpose, this paper presents a method for extracting terrain information, that is, slope and roughness from elevation maps as a prior step of traversability analysis. Slope is extracted using the curve fitting based on the least squares method and roughness using three metrics and their weighted average. The effectiveness of the proposed method is verified on both a fractal map and the world model map of a real terrain.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.105-110
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• 2014

This paper presents the hysteresis friction of a sliding elastomer on various types of surfaces. The hysteresis friction is calculated by means of an analytical model which considers the energy spent by the local deformation of the rubber due to surface asperities. By establishing the fractal character of the surfaces, the contribution to rubber friction of roughness at different length scales is accounted for. High resolution surface profilometer is used in order to calculate the main three surface descriptors and the minimal length scale that can contribute to hysteresis friction. The results show that this friction prediction can be used in order to characterize in an elegant manner the surface morphology of various surfaces and to quantify the friction coefficient of sliding rubber as a function of surface roughness, load and speed.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.6
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• pp.50-56
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• 1997

As the purpose of the breakdown prediction of three degradation of insulating materials caused by partial discharge occurring at various defects in the polymer insulator itself and at the interfaces between electrodes and the insulating materials. Treeing due to partial discharge os one of the main causes of breakdown of the insulating materials. Recently, the necessity of establishing the way to diagnoses the aging of insulation materials and to predict of insulation breakdown become improtant. The purpose of our work are to use acoustic emission System and fractal dimension and to investigated the treeing phenomena in polymeric insulation under appliec AC voltage 11[kV] with an artificial needleshaped void(1.5[mm]) using the above system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.636-641
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• 2000

The purpose of this study is assessing the characteristics of surface aging and recovery of hydrophobicity for silicone rubber which takes a great interest as outdoor insulation recently subjected to the combined stressed of salt fog and AC power. The methods for assessing are contact angle ATR-FRIR, AFM and XRD. In addition salt fog method is adopted as the artificial contamination experiment and AC power is applied 24 hour on and 24 hour off repeatedly for 5 cycles. The results suggest that degraded surface was more rough than virgin but was restored water repellency through the off cycle. It was due to not only the formation of fractal surface but also maintenance of hydrophobic surface by diffusion of low molecular oil. Although surface recovers initial hydropohbicity there are possibilities of decreasing electrical performance due to irreversable changes such as depolymerization of surface and loss of filler particles. This fact is confirmed by surface conductivity measurement showing that the degradation is significant and the recovery of hydrophobicity is imperfect as the energized cycle increases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.609-616
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• 2002

The characteristics of mechanical behavior are investigated for Ti-6Al-4V alloy. Four kinds of the specimens are prepared under different heat treatments in order to produce different microstructures. In the present investigations, impact, tensile and fatigue crack growth tests are performed for each test specimen. The results obtained through the investigations are compared. Additionally fr actal dimensions of crack pass are obtained using the box counting method. The results are, 1) the microstructures shows as equiaxed, bimodal and Widmanstatten microstructures respectively, 2) the impact energy and elongation are superior fur the bimodal microstructure, and the hardness and tensile strength are superior fur the Widmanstatten microstructure, 3) the fatigue crack growth rate is similar to all microstructures in low ΔK region while that of equiaxed microstructure is the largest, and that of Widmanstatten microstructure is the lowest in high ΔK region respectively, 4) the fractal dimension D of Widmanstatten microstructure shows higher value than that of the equiaxed and bimodal microstructures under 200 magnification view of the SEM micrographs.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.2
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• pp.1-20
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• 2005

The purpose of this paper is to classify two study sites into the biotope types and investigate the landscape ecological characteristics of them. This will be available for the rural planning in the aspect of environmental preservation. The summaries of the result are as follows. 1) In the result of the area assessment in biotope groups, a dry field (32%) and a paddy field (28%) are more than 50%, but settlement space and water space are less than 10%. The result shows the land use condition of rural areas. 2) In the investigation result of elongation, running water spaces are higher than other biotope groups relatively, it is because they long shaped and 1-3m narrow. 3) In case of Fractal index analysis, residential spaces and cultivated lands are investigated to be lower in numerical value, it is because they have the definite borders and get simple in the border of landscape by human intervention. 4) In case of dispersion degree, the dry field has the highest value because they are located close by forests spread widely around study sites. It means that the land which is used by artificial purpose get more value rather than natural lands 5) In the connectivity analysis, a paddy field and a residential space appear the highest. It is because residence spaces spread intensively through roads and a paddy field, through streams. 6) In rural landscape, the diversity of landscape is investigated to be simple. A paddy field and a dry field contain small sized patches that have been divided by human intervention. Besides, there appear much different vegetation around waterways and farm-roads.