• Journal of Magnetics
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• v.16 no.3
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• pp.300-303
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• 2011

The effect of the hot-compaction temperature on the microstructure and magnetic properties of anisotropic nanocrystalline magnets was investigated. The hot-compaction temperature was found to impact both the magnetic properties and the microstructure of die-upset magnets. The remanence of the isotropic precursor increases slightly with the improved hot-compaction temperature, and the grains start to grow on the flake boundary at higher hot-compaction temperatures. After hot deformation, it was found that the change in the magnetic properties was the inverse of that observed with the hot-compaction temperature. Microstructural investigation showed that die-upset magnets inherit the microstructural characteristics of their precursor. For the die-upset magnets, hot pressed at low temperature, scarcely any abnormal grain growth on the flake boundary can be seen. For those hot pressed at higher temperatures, however, layers with large equiaxed grains could be observed, which accounted for the poor alignment during the hot deformation, and thus the poor magnetic properties.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.822-823
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• 2006

The compaction and sintering behavior of zirconium titanate $(ZrTiO_4)$ was investigated by means of the measurement of sintering density and shrinkage, and the observation of microstructure. With increasing the content of $Al_2O_3$ additive, $Al_2O_3$-modified zirconium titanate samples fired at $1300^{\circ}C$ showed the anisotropic shrinkage behavior that the upper region of sintered body has higher sintering shrinkage than the low region. This difference of sintering shrinkage decreased with increasing firing temperature from 1300 to $1400^{\circ}C$. The SEM micrographs of powder compation show that the anisotropic shrinkage behavior is related with non-uniform density in a uniaxial compaction.

• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.45-49
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• 2010

The roller compacted concrete (RCC) is supposed to be isotropic, whereas the compaction of this material, which is achieved using the same machines used for the soil, appears only unidirectional, making the RCC an anisotropic material. In this experimental work, the influence of the phenomenon of compaction on the isotropy of the RCC is studied. This study was carried out through an evaluation of the compressive strengths and ultrasonic tests which were used for measurements of the elastic modulus and the dynamic Poisson's ratio of the RCC as well as a qualitative judgement of the RCC aspect at the hardened state. The results of this work proved the anisotropy of the RCC and they showed the sensitivity of the mechanical strengths and the elastic modulus to the compaction direction.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.685-692
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• 2000

Vertical drain used improvement soft clay is made of not only decreasing construction time but also increasing the ground strength during some decades. As, it is applied to improvement soft clay with vertical drain, it is designed by the result that is caused by oedemeter test ignored anisotropic of the ground related to consolidation conditions. When we are expected consolidation conditions, the most important factors is soil of compaction and water permeability. Above all, anisotropic of the ground permeability show the results which differ between vertical and radial drainage. Recently, We study for radial consolidation coefficient and permeability coefficient that utilized Rowe Cell Consolidation and permeability tester but, it dont use well because of not only a supply lack also difficulty of test. The paper experimented with searching anisotropic of the ground so there are Rowe Cell test, standard consolidation tester and modified standard consolidation test that have pohang's soft clay ground. Therefore, we find anisotropic of the ground and a tester of easy use more than before. We made a comparison test result between the devised tester and Rowe Cell tester, Also, we learned average degree of consolidation for partial penetrating vertical drains. We were found relations as effective stress-void and effective stress-permeability coefficient through those tests.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.09a
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• pp.73-78
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• 2000

The reinforced soil has been widely used for constructing retaining walls and embankment with steep slope. However, the benefits of soil reinforcing are often-restricted by a lack of good quality backfill material. In this study, plane strain compression tests were carried out to study the effects of preloading on the behavior of geosynthetic-reinforced saturated clay. For the unreinforced and reinforced soil, drained and undrained shearing tests were peformed after anisotropic consolidation in a constant strain rate. A preoading test was carried out by preloading, creep, unloading, aging and undrained shearing after anisotropic consolidation(K=0.3, σ'₃=50 kPa). It was observed that a reinforced clay, Kanto loam, can have a great initial secant modulus in undraind condition by well compaction and over consolidation. The results shown that the increasing of drained strength should be used to apply a large preloading in the case of reinforced clay.

• Structural Engineering and Mechanics
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• v.5 no.6
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• pp.679-689
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• 1997

The damage of concrete subjected to multiaxial complex loading involves strong anisotropy due to its highly heterogeneous nature and the geometrically anisotropic characteristic of the microcracks. A comprehensive description of concrete damage is proposed by introducing a fourth-order anisotropic damage tenser. The evolution of damage is assumed to be related to the principal components of the current states of stress and damage. The unilateral effect of damage due to the closure and opening of microcracks is taken into account by introducing projection tensors that are also determined by the current state of stress. The proposed damage model considers the different kinds of damage mechanisms that result in different failure modes and different patterns of microdefects that cause different unilateral effects. This damage model is embedded in a thermomechanically consistent constitutive equation in which hardening and the triaxial compression caused shear-enhanced compaction can also be taken into account. The validity of the proposed model is verified by comparing theoretical and experimental results of plain and steel fiber reinforced concrete subjected to complex triaxial stress histories.

• Journal of the Korean Geotechnical Society
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• v.26 no.6
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• pp.21-28
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• 2010

Decomposed granite soil is the most common type of soils. The measurement of the stress-strain-strength behavior of anisotropic decomposed granite soils is very important for the deformation and stability analysis of slopes, retaining walls, excavations. A series of unsaturated-drained triaxial compression tests were performed to know unsaturated strength properties. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane): 0, 45 and 90 degrees. The compression strain of specimens subjected to an isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clearly shown with low confining stress. The effect of the sedimentation angle on the compressive strength and deformation was more evident in saturated specimens. A new method of predicting the shear strength of unsaturated decomposed granite soils, considering compaction angles, was proposed.

• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.5-12
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• 2005

In order to investigate the strength and deformation anisotropy of compacted decomposed granite soils, a series of unsaturated-drained triaxial compression tests were performed. The sample used in the study was decomposed granite soil from Shimonoseki in Yamaguchi prefecture. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane), 0, 45 and 90 degrees. The compression strain of specimens subjected to isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clear with low confining stress. Moreover, it was recognized that although the sedimentation angle and preparation methods were different, the dilatancy rate was relative to the increment of strength due to dilatancy. Therefore, it may be concluded that the compacted specimen has anisotropic mechanical properties similar to those of sand with initial fabric anisotropy.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.6
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• pp.64-73
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• 1996

The three-dimensional strength behavior of compacted decomposed granite soil was studied using cubical triaxial tests with independent control of the three principal stresses. All specimens were loaded under conditions of principal stress direction fixed and aligned with the directions of compacted plane. For comparable test conditions, the major principal strain and volume strain to failure were smallest when the major principal stress acted perpendicular to the compacted plane. The opposite extremes were obtained when the major principal stress acted parallel to the compacted plane. In cubical triaxial tests with same b values and with ${\theta}$ values in one of three sectors of the octahedral plane, independent of the range of ${\theta}$, higher friction angles are obtained in tests with b greater than in triaxial compression tests in which b 0.0, Comparison between the results of the drained cubical triaxial tests on lksan compacted decomposed granite soil and the cross section of the Mohr-Coulomb failure surface as well as the cross section of the Mohr-Coulomb failure surface were made. Lade's isotropic failure criterion based on vertical specimens overestimates the strengths for tests performed with values of 0 between 90˚ and 1 50˚ the Mohr-Coulomb criterion generally underestimates the strengths of tests performed with values of ${\theta}$ between $0^{\circ}$ and $180^{\circ}$ except around the $120^{\circ}$.