• ETRI Journal
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• v.46 no.4
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• pp.571-580
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• 2024

A compact triple-band porous electromagnetic bandgap structure-loaded coplanar-waveguide-fed wearable antenna is introduced for applications of wireless body area networks. The porous structure is aimed to create a stopband or bandgap in the electromagnetic spectrum and increase breathability. The holes in the bottom electromagnetic bandgap surface increase the inductance, which in turn increases the bandwidth. The final design resonates at three bands with impedance bandwidths of 264 MHz, 100 MHz, and 153 MHz and maximum gains of 2.18 dBi, 6.75 dBi, and 9.50 dBi at 2.45 GHz, 3.5 GHz, and 5.5 GHz, respectively. In addition, measurements indicate that the proposed design can be deformed up to certain curvature and withstand human tissue loading. Moreover, the specific absorption rate remains within safe levels for humans. Therefore, the proposed antenna can suitably operate in the industrial, scientific, and medical, Bluetooth, Wi-Fi, and WiMAX bands for potential application to wireless body area networks.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.367-375
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• 2010

Understanding the interactions between earth materials and fluids is essential for studying the diverse geological processes in the Earth's surface and interior. In order to better understand the interactions between earth materials and fluids, we explore the effect of specific surface area and porosity on structural parameters of pore structures. We obtained 3D pore structures, using random packing simulations of porous media composed of single sized spheres with varying the particle size and porosity, and then we analyzed configurational entropy for 2D cross sections of porous media and cube counting fractal dimension for 3D porous networks. The results of the configurational entropy analysis show that the entropy length decreases from 0.8 to 0.2 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$, and the maximum configurational entropy increases from 0.94 to 0.99 with increasing porosity from 0.33 to 0.46. On the basis of the strong correlation between the liquid volume fraction (i.e., porosity) and configurational entropy, we suggest that elastic properties and viscosity of mantle melts can be expressed using configurational entropy. The results of the cube counting fractal dimension analysis show that cube counting fractal dimension increases with increasing porosity at constant specific surface area, and increases from 2.65 to 2.98 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$. On the basis of the strong correlation among cube counting fractal dimension, specific surface area, and porosity, we suggest that seismic wave attenuation and structural disorder in fluid-rock-melt composites can be described using cube counting fractal dimension.

• Spatial Information Research
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• v.8 no.2
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• pp.243-255
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• 2000

The spatial distribution characteristics and patterns of geographic features in space can be understood through a variety of analysis techniques. The scale is one of most important factors in spatial analysis techniques. This study is aimed at identifying the characteristics of spatial data with a coarser spatial resolution and finding procedures for spatial resolution in operational scale. To achieve these objectives, this study selected LANSAT TM imagery for Sunchon Bay, a coastal wetland for a study site, applied the indices for representing scale characteristics with resolution, and compared those indices. Local variance and fractal dimension developed by previous studies were applied to measure the textual characteristics. In this study, Moran s I was applied to measure spatial pattern change of variance data which were generated from the process of coarser resolution. Drawing upon the Moran s I of variancedata was optimum technique for analysing spatial structure than those of previous studies (local variance and fractal dimension). When the variance data represents maximum Moran´s I at certainly resolution, spatial data reveals maximum change at that resolution. The optimum resolution for spatial data can be explored by applying these results.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.3
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• pp.16-22
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• 1999

The various spatial structure of biological habitat has tighten relationship with biodiversity. Due to increasing of population, development of agriculture and urban structure, various change of landscape has became these days. These change of landscape has raised the decrease of habitat and landscape fragmentation. This paper summarizes research to analysis vegetation index according to P/A ratio, Shape Index, and Fractal dimension using Landsat Thematic Mapper(TM). The analysis of landscape fragmentation using NDVI(Normalized Difference Vegetation Index) 0.5~1 has the most profitable for detection of vegetation fragmentation. The analysis of vegetation index of Seoul and Kyunggi province has also showed that Fractal dimension has the most fragmentation index. In near future, time series analysis is needed for fragmentation of vegetation on the same area, and for various landuse of fragmentation analysis. These researches were carried out for preservation strategy of vegetation and biodiversity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.90-96
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• 2018

In this study, the mechanical and micro-structural change of cement pastes incorporating Stainless-Steel Slag Argon Oxygen Decarburization Slag (STS-A) containing ${\gamma}-C_2S$ as a carbon capture materials were investigated with carbonation curing condition. ${\gamma}-C_2S$ is non-hydraulic, therefore does not react with water. But ${\gamma}-C_2S$ has a reactivity under carbonation curing condition with water. The reaction products fill up the pore in pastes. The microstructure of STS-A blended cement pastes could be densified by this reaction. The pore structure of cement pastes incorporating STS-A was measured using mercury intrusion porosimetry (MIP) after carbonation curing ($CO_2$ concentration is about 5%). Also the fractal characteristics were investigated for the effect of carbonation curing on the micro-structural change of paste specimens. From the results, the compressive strength of carbonated specimens incorporating STS-A increased and pore-structure of carbonated paste is more complicated.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.110-116
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• 2008

This paper presents a new postprocessing method to eliminate the false minutiae, that caused by the skelectonization of fingerprint image, and an image compression method using Isometric Self Organizing Map(ISOSOM). Since the SOM has simple structure, fast encoding time, and relatively good classification characteristics, many image processing areas adopt this such as image compression and pattern classification, etc. But, the SOM shows limited performances in pattern classification because of it's single layer structure. To maximize the performance of the pattern classification with small code book, we a lied the Isometric SOM with the isometry of the fractal theory. The proposed Isometric SOM postprocessing and compression algorithm of fingerprint image showed good performances in the elimination of false minutiae and the image compression simultaneously.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.525-535
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• 2017

In order to produce hydrophilic coating solution, which has superior antifogging and antifouling effect on the glass surface of solar cell module as well as improving photovoltaic efficiency, nanosilica was dispersed in an aqueous solution of Tween 20 and fluorosurfactant composed of decafluorobutane and polyethylene glycol. The antifogging effect at high temperature was excellent for all the coating solutions containing nanosilica, but the antifouling effect was observed when the content of nanosilica was over 6 wt%. As the content of fluorosurfactant increased, the initial water contact angle slightly increased and the antifogging effect remained well until 500 wiping with wet $Wipeol^{(R)}$. The antifouling effect was also excellent regardless of the content of fluorosurfactant, thus 0.1 wt% of the fluorosurfactant was enough for a coating solution production. From the AFM results, when 0.1 wt% to 0.3 wt% of the fluoro surfactant was added, the fractal structure of the coated glass surface was clearly existed and contributed to the better antifouling effect. The transmittance of coated glass surface was highest in TL-1 coating solution containing 0.1 wt% of fluorosurfactant, and the addition of fluorosurfactant in a larger amount than 0.1 wt% did not improve the transmittance. This result is in good agreement with the previous AFM result which shows a high surface roughness as well as a fractal structure formation for the TL-1 coating solution.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.351-360
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• 2015

Human influence on soil formation has dramatically increased with human civilization and industry development. Increase of anthropogenic soils induced researches on the anthropogenic soils; classification, chemical and physical characteristics of anthropogenic soils and plant growth from anthropogenic soils. However there have been no comprehensive analyses on soil pore or physical properties of anthropogenic soils from 3 dimensional images in Korea. The objectives of this study were to characterize physical properties of anthropogenic paddy field soils by depth and to find differences between natural and anthropogenic paddy field soils. Soil samples were taken from two anthropogenic and natural paddy field soils; anthropogenic (A_c) and natural (N_c) paddy soils with topsoil of coarse texture and anthropogenic (A_f) and natural (N_f) paddy soils with topsoil of fine texture. The anthropogenic paddy fields were reestablished during the Arable Land Remodeling Project from 2011 to 2012 and continued rice farming after the project. Natural paddy fields had no artificial changes or disturbance in soil layers up to 1m depth. Samples were taken at three different depths and analyzed for routine physical properties (texture, bulk density, etc.) and pore properties with computer tomography (CT) scans. The CT scan provided 3 dimensional images at resolution of 0.01 mm to calculate pore radius size, length, and tortuosity of soil pores. Fractal and configuration entropy analyses were applied to quantify pore structure and analyze spatial distribution of pores within soil images. The results of measured physical properties showed no clear trend or significant differences across depths or sites from all samples, except the properties from topsoils. The results of pore morphology and spatial distribution analyses provided detailed information of pores affected by human influences. Pore length and size showed significant decrease in anthropogenic soils. Especially, pores of A_c had great decrease in length compared to N_c. Fractal and entropy analyses showed clear changes of pore distributions across sites. The topsoil layer of A_c showed more degradation of pore structure than that of N_c, while pores of A_f topsoil did not show significant degradation compared with those of N_f. These results concluded that anthropogenic soils with coarse texture may have more effects on pore properties than ones with fine texture. The reestablished paddy fields may need more fundamental remediation to improve physical conditions.

• Journal of Fashion Business
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• v.18 no.1
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• pp.164-181
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• 2014

As the boundary between fashion and architecture is getting blurred, the interactions of the two fields are turning out abundant as well as essential. This study investigates the tectonic strategies in architectural fashion design as a novel aesthetic in the 21st century by combining literary survey and case analysis on architecture and contemporary fashion. The tectonic strategies in the works of architectural fashion designers were categorized as follows: organic geometry, technological garment construction, and independent space. Organic geometry transforms basic geometric shapes into subtle organic forms after being thrown on the body. Technological garment construction explores the garment structure and volume by applying the structural principle of suspension and fractal geometry. Independent space refers to maintaining the firm three-dimensionality of garment structure which keeps the distance from the body, assuming the similarity to architecture.

• Journal of the korean society of oceanography
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• v.35 no.1
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• pp.11-15
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• 2000

The scaling behavior of random fractals and multifractals is investigated numerically on the seabottom depth in the seabottom topography. In the self-affine structure the critical length for the crossover can be found from the value of standard deviations for the seabottom depth. The generalized dimension and the spectrum in the multifractal structure are discussed numerically, as it is assumed that the seabottom depth is located on a two-dimensional square lattice. For this case, the fractal dimension D$_0$ is respectively calculated as 1.312476, 1.366726, and 1.372243 in our three regions, and our result is compared with other numerical calculations.