• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.301-303
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• 2008

In order to investigate the influence of anisotropy on formability and also to obtain guidelines for the stamping process design in friction stir welded TWB (tailor welded blank), the aluminum ally 6111-T4 sheet was welded with three different types of combination: RD||RD, TD||RD and TD||TD (Here, RD and TD mean the rolling direction and transverse direction, respectively) and then hemisphere dome stretching and cylindrical cup drawing tests were carried out. In addition, the numerical analysis was performed to confirm the validity of experimental results. For the numerical analysis, the non-quadratic orthotropic yield function, Yld2004-18p was utilized to represent precise anisotropic properties.

• 한국세라믹학회지
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• 제49권4호
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• pp.347-351
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• 2012

Vermiculite-silica composites with a layered structure were fabricated by adding cellulose fibers as a pore former and by a simple uniaxial pressing and subsequent sintering process. Three different combinations of additives were used and their effects on the compressive strength and thermal conductivity of the composites were investigated. Both compressive strengths (42-128 MPa) and thermal conductivities (0.75-1.48 $W/m{\cdot}K$) in the direction perpendicular to the pressing direction (T) were higher than those (19-81 MPa and 0.32-1.04 $W/m{\cdot}K$) in the direction parallel to the pressing direction (S) in all samples. The anisotropy in both properties was attributed to the microstructural anisotropy, which was caused by the layered structure developed in the composites.

• 한국생산제조학회지
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• 제9권6호
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• pp.82-88
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• 2000

The effect of the welding for the offshore structure in the TMCP steel on the fatigue crack propagation rate and crack opening-and-closure behavior was examined. The welding anisotropy of the TMCP steel and crack propagation characteristics of the excessive loading were reviewed. (1) It seemed that a heat which was generated by the welding made a compressive residual stress over the base metal, so fatigue crack propagation rate was placed lower than in case of the base metal. (20 In the base metal, an effect of the anisotropy which has an effect of fatigue crack propagation rate of the excessive load and the constant amplitude laos was not found but in the welding material case, fatigue crack propagation rate of the excessive load in the specimen of the width direction was located in the retard side as compared with a specimen rolling direction. (3) A crack opening ratio of the used TMCP stel in this study was not changed after excessive loading but a retard phenomenon of crack propagation was observed. Consequently, it was thought that all of the retard phenomenon of crack propagation did not only a cause of the crack opening-and-closure phenomenon.

• 동력기계공학회지
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• 제15권1호
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• pp.39-44
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• 2011

This study was to investigate the effects of stress ratio and anisotropy on Fatigue Crack Propagation(FCP) behavior of rolled magnesium alloy AZ31B. The experimental materials were a Mg-Al-Zn magnesium alloy. The FCP test was conducted on compact tension specimen by a servo-hydraulic fatigue testing machine in air at room temperature. Compact tension specimens were prepared from the extruded parallel and vertical rolling direction. The test condition was frequency of 10Hz and sinusoidal load stress ratios are 0.1 and 0.7. The FCP rates was automatically measured by a compliance method. In the case of the FCP of AZ31B, the FCP of both direction of LT and TL by anisotropy of specimens are almost same value. In lower stress ratio, the FCP of the LT, TL specimens are increased in lower ${\Delta}K$ region but higher ${\Delta}K$ regions are almost same value. Finally, the result of observed the surface crack, it expressed the quasi-cleavage fracture in lower ${\Delta}K$ region and straight mark on the aspect of the facet in high ${\Delta}K$ region.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.103-110
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• 2003

This study is as for shale that attract recently geotechnical engineer more and more. like sedimentary rocks and metamorpic rocks, shales have many problem with anisotropy for stength and deformation and they have many problems with quick weathering progress and differential weathering of alternate bedding. In foreign countries, many renowned schalors, like Jaeger(1960),McLamore,Gray(1967),Donath(1972),Nova(1980),Hoek&Brown(1980),Ranamurthy(1985), have already studied for a variety of characteristic and announced high level results of their studies. In domestic also, there are many scholars who have announced high level research papers for shale. this study is a part of these stream. and this study not only analyzed strength anisotropy characteristic along with direction of testing(two-direction) by using point-load test(log-log method) but also compared uniaxial strength between the maximum saturated and dried condition. In this study, we also conducted slaking test. these results of slaking test show weathering characteristic of shales. also, we made the most of field data that obtained during slope stability project and we noticed that RQD measured in the field is much differ from drilled core RQD. In order to come close two different value or access to reality, we suggest new RQD method that artificially reduce RQD by separating core with light hand force.

• 한국전기전자재료학회논문지
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• 제17권8호
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• pp.888-892
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• 2004

It is necessary to develop soft magnetic layer with high saturation magnetization 4 $\pi{M}_s$ and in-plane magnetic anisotropy field Hk for soft magnetic underlayer of perpendicular magnetic recording media with high signal to noise ratio. Fe-Co-B layer with high 4 $\pi$Ms of about 23 kG deposited on Ni-Fe and Ni-Fe/Si seedlayer exhibited very high in-plane magnetic anisotropy filed Hk of about 280 and 380 Oe, respectively, In-plane XRD studies clarified that the lattice spacing of planes along the easy axis direction was longer than that along the hard axis direction in the Fe-Co-B layers with high Hk. These results indicate that high Hk of Fe-Co-B/Ni-Fe and Fe-Co-B/［Ni-Fe/si］ layers were resulted from magnetoelastic anisotropy owing to a residual stress. Moreover, the high Hk in the Fe-Co-B/Ni-Fe layer was maintained until 30$0^{\circ}C$ annealing temperature.

• 한국정밀공학회지
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• 제25권11호
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• pp.126-133
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• 2008

Rapid Prototyping (RP) has been widely used for rapid development of prototypes in various industrial fields. In recent years, a new requirement in RP industry has issued so as to directly manufacture a functional prototype which has enough mechanical properties to be used as a functional part. The RP prototype, however, has a limitation in mechanical properties due to its layer-by-layer manufacturing process. This manufacturing process results in anisotropy of the prototype, especially showing weakness in the building direction. In the present work, we performed tensile tests for RP prototypes in order to determine directional mechanical properties. The test specimens were made by using $Eden330^{TM}$ by Object Geometries Ltd. Finite element analyses considering material anisotropy were then carried out for RP prototypes with various building directions. Effect of the building direction on the mechanical strength was investigated through the analysis, and compared with experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.287-290
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• 2005

The shearing and punching processes are analyzed with the finite element method using an isotropic material model. The experimental result in the punching process shows that final radiuses of sheet metal according to the rolling direction and transverse direction are different because of the material anisotropy. The material anisotropy is induced by complicated large deformation in the polycrystalline aggregate. The contact region between the punch and sheet metal experiences severe deformation such as shear, compression and tension in the punching process. In this paper, the analysis of punching process for Al 1100 is performed with the ABAQUS Standard. The analysis of texture development and evolution is carried out based on the deformation history in the punching process. The deformation histories are extracted by UMAT in the ABAQUS Standard. The torture development is investigated with the pole figure and yield surface during the punching process.

• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.724-728
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• 2005

Electro-optic characteristics of reflective hybrid aligned liquid crystal (LC) cell driven by fringe field using a nematic LC with positive dielectric anisotropy have been studied. Optimized optical configurations are achieved by using a single polarizer, half-wave film and a cell with quarter-wave retardation. The simulation results shows an optimum cell retardation of $0.30{\mu}m$. This value may allow a practical cell gap larger than $3{\mu}m$, which makes it easy to control in the manufacturing process. Furthermore, this LC cell with optimized cell parameters shows low wavelength dispersion and the contrast ratio greater than 5 over exists about $100{\circ}$ in vertical direction and $160{\circ}$ in horizontal direction. Also, when using the LC with positive dielectric anisotropy rather than negative dielectric anisotropy, the display shows low power consumption and fast response time.

• 한국자기학회지
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• 제26권2호
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• pp.50-54
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• 2016

본 연구에서는 교환 결합력을 갖는 CoFe/MnIr 박막 재료의 각도에 따른 강자성 공명 선폭 변화 특성을 분석하였다. 선폭의 최대 및 최소값은 교환 결합력에 의한 일방 이방성의 자화 곤란축 및 용이축 방향에서 각각 관측되었으며, 고정된 MnIr의 스핀에 의한 교환 바이어스 자기장의 각도 의존성과 일치하였다. 따라서, 최대 선폭은 고정된 MnIr 스핀의 반대 방향에서 자기장 방향으로 꼬여있는(twist) CoFe의 자화에 기인한다. 한편, CoFe 단일 박막에 비하여 증가된 최소 선폭은 각도 의존성이 없는 회전 이방성 자기장과 관련되며, 선폭 증가의 원인은 MnIr 입도의 자화 용이축 분포 특성으로 설명된다.