• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.523-528
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• 2004

This study proposed an anisotropic diffusion restoration fer image classification. The anisotropic diffusion restoration uses a probabilistic model based on Markov random field, which represents geographical connectedness existing in many remotely sensed images, and restores them through an iterative diffusion processing. In every iteration, the bonding-strength coefficient associated with the spatial connectedness is adaptively estimated as a function of brightness gradient. This study made experiments on the satellite images remotely sensed on the Korean peninsula. The experimental results show that the proposed approach is also very effective on image classification in remote sensing.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.407-414
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• 2002

The knowledge of interaction of electromagnetic waves in composite structures is important for designing the shielding structure for antenna such as radome. Recently, radomes are constructed in the form of foam core sandwich structures that have many mechanical advantages such as high strength, long fatigue life, low density and adaptability to the intended function of structure. However, the propagation of electromagnetic waves is affected by high anisotropic permeability and loss tangent of the composite skin. In this study, the analytical model to understand the propagation of electromagnetic waves in the anisotropic composites and foam core sandwich structures with composite skins was proposed. Numerical analyses of unidirectional composites and foam core sandwich structure as a function of incident angle were performed. From the results of analysis, the general tendencies of transmittance of electromagnetic wave through composites and foam core sandwich structure were obtained.

• Korean Journal of Remote Sensing
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• v.31 no.1
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• pp.21-28
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• 2015

The essential idea of de-noising is referring to neighboring pixels of a center pixel to be updated. Conventional adaptive de-noising filters use local statistics, i.e., mean and variance, of neighboring pixels including the center pixel. The drawback of adaptive de-noising filters is that their performance becomes low when edges are contained in neighboring pixels, while anisotropic diffusion de-noising filters remove adaptively noises and preserve edges considering intensity difference between neighboring pixel and the center pixel. The anisotropic diffusion de-noising filters, however, use only intensity difference between neighboring pixels and the center pixel, i.e., local statistics of neighboring pixels and the center pixel are not considered. We propose a new connectivity function of two adjacent pixels using statistics of neighboring pixels and apply connectivity function to diffusion coefficient. Experimental results using an aerial image corrupted by uniform and Gaussian noises showed that the proposed algorithm removed more efficiently noises than conventional diffusion filter and median filter.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.131-142
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• 1999

The objective of this study is to perform finite element analyses using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening constitutive model had been developed in a companion paper, and was then formulated by implicit stress integration and consistent tangent moduli. A nonlinear finite element analysis program was coded including the algorithm, and as a result, the nonlinear solution was accurately calculated and converged to be asymptotically quadratic. In the analysis of a test embankment it was found that the proposed model could predict the displacement of soils more reasonably than the analysis with von Mises type model. In addition the proposed model could predict accurately the actual behavior through the reanalysis of the problem by a reasonable evaluation of the strength parameter.

• Transactions of Materials Processing
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• v.25 no.2
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• pp.91-95
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• 2016

This paper is concerned with modeling of a ductile fracture criterion for sheet metal considering anisotropy to predict the sudden fracture of advanced high strength steel (AHSS) sheets during complicated forming processes. The Lou−Huh ductile fracture criterion is modified using the Hill’s 48 anisotropic plastic potential instead of the von Mises isotropic plastic potential to take account of the influence of anisotropy on the equivalent plastic strain at the onset of fracture. To determine the coefficients of the model proposed, a two dimensional digital image correlation (2D-DIC) method is utilized to measure the strain histories on the surface of three different types of specimens during deformation. For the derivation of an anisotropic ductile fracture model, principal stresses (𝜎₁,𝜎₂, 𝜎₃) are expressed in terms of the stress triaxiality, the Lode parameter, and the equivalent stress (𝜂_𝐻, 𝐿,) based on the Hill’s 48 anisotropic plastic potential. The proposed anisotropic ductile fracture criterion was quantitatively evaluated according to various directions of the maximum principal stress. Fracture forming limit diagrams were also constructed to evaluate the forming limit in sheet metal forming of AHSS sheets over a wide range of loading conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.284-287
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• 2001

Multi-pole anisotropic Sr-ferrite sintered magnets has been studied by powder injection molding under applied magnetic field. The orientation of anisotropic Sr-ferrite powders higher than 80% during injection molding is achieved at the following conditions; apparent viscosity lower then 2500 poise in 1000 $sec^{-1}$ shear rate and applied magnetic field higher then 4 kOe. For the high fluidity and strength of injection molded compact, and the effective binder removal without defects during solvent extraction and thermal debinding, the optimum multi-binder composition is paraffin wax(PW)/carnauba wax(CW)/HDPE = 50/25/25 wt%. The rate of binder removal is proportional to the mean particle size of Sr-ferrite powders whereas it is inversely proportional to the content of Sr-ferrite powders and the sample thickness. The high magnetic properties of Sr-ferrite sintered magnets are; 3.8 kG of remanent flux density, 3.4 kOe of intrinsic coercivity, and 1.2 kG of surface flux density (l-mm-thick) in the direction of applied magnetic field.

• Korean Journal of Materials Research
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• v.30 no.3
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• pp.105-110
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• 2020

Cu/PET composite films are widely used in a variety of wearable electronics. Lifetime of the electronics is determined by adhesion between the Cu film and the PET substrate. The formation of an anisotropic nanostructure on the PET surface by surface modification can enhance Cu/PET interfacial adhesion. The shape and size of the anisotropic nanostructures of the PET surface can be controlled by varying the surface modification conditions. In this work, the effect of Cu/PET interface nanostructures on the failure mechanism of a Cu/PET flexible composite film is studied. From observation of the morphologies of the anisotropic nanostructures on plasma-treated PET surfaces, and cross-sections and surfaces of the fractured specimens, the Cu/PET interface area and nanostructure width are analyzed and the failure mechanism of the Cu/PET film is investigated. It is found that the failure mechanism of the Cu/PET flexible composite film depends on the shape and size of the plasmatreated PET surface nanostructures. Cu/PET interface nanostructures with maximal peel strength exhibit multiple craze-crack propagation behavior, while smaller or larger interface nanostructures exhibit single-path craze-crack propagation behavior.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
• /
• pp.284-287
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• 2001

Multi-pole anisotropic Sr-fertile sintered magnets has been studied by powder injection molding under applied magnetic field. The orientation of anisotropic Sr-ferrite powders higher than 80% during injection molding is achieved at the following conditions; apparent viscosity lower then 2500 poise in 1000 sec$\^$-1/ shear rate and applied magnetic field higher then 4 kOe. For the high fluidity and strength of injection molded compact, and the effective binder removal without defects during solvent extraction and thermal debinding, the optimum multi-binder composition is paraffin wax(PW)/carnauba wax(CW)/HDPE = 50/25/25 wt%. The rate of binder removal is proportional to the mean particle size of Sr-ferrite powders whereas it is inversely proportional to the content of Sr-ferrite powders and the sample thickness. The high magnetic properties of Sr-ferrite sintered magnets are; 3.8 kG of remanent flux density, 3.4 kOe of intrinsic coercivity, and 1.2 kG of surface flux density (1-mm-thick) in the direction of applied magnetic field.

• Structural Engineering and Mechanics
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• v.3 no.1
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• pp.91-103
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• 1995

An analysis to determine shear centers for anisotropic elastic thin-walled composite beams, cantilevered and loaded transversely at the free end is presented. The shear center is formulated based on familiar strength of material procedures analogous to those for isotropic beams. These procedures call for a balancing of torsional moments on the cross sectional surface and lead to a condition of zero resultant torsional couple. As a consequence, due the presence of anisotropic coupling, certain non-classical effects are manifested and are illustrated in two example problems. The most distinguishing result is that twisting may occur for composite beams even if shear forces are applied at the shear center. The derived shear center locations do not depend on any specific anisotropic bending theories per se, but only on the values of bending and shear stresses which such theories produce.

• Tunnel and Underground Space
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• v.10 no.2
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• pp.165-172
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• 2000

When tunnels or underground structures are constructed in anisotropic rock mass, designers and constructors have to consider the anisotropic characteristics in rock mass because their physical and mechanical properties are depended on the anisotropic angles(${\beta}$). In this study, therefore, we have first investigated the mechanical behavior of the gneiss specimen from lab. tests, and then have analysed the behavior of specimens for to the transversely isotropic model in elastic medium using the FLAC program. The results of this study were summarized as follows; 1) In the result of the variation tests, in general, the properties of strength were depended on the angle of inclination in spite of the hard rock. And except for the shear strength test, the lowest and peak stress were appeared at 60$^{\circ}$ and 90$^{\circ}$respectively. 2) The results of specimen modeling analysis using FDM well indicated the mechanical behaviors of the specimen of transversely isotropic model.