• 전자공학회논문지A
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• 제32A권12호
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• pp.166-172
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• 1995

A novel passive TE/TM polarization mode converter is fabricated by using poled polymer waveguides. The optic axis of the poling induced waveguide is slowly rotated by using a slowly varying structure of poling electrodes. Thus the polarization conversion is achieved as the guided mode propagates through the waveguide. The proposed device is simulated by a full vectorial beam propagation method (VBPM) for anisotropic medium. For the rotation length of 1 mm, the TE polarization of the guided mode is successfully converted to the TM polarization with negligible loss. Based on the simulation results, we fabricated the polarization converter which is tested by using 1.3 $\mu$m laser diode. TE to TM mode conversion is observed with a polarization extinction ratio higher than 30 dB, and the excess loss is less than 1 dB. The polarization conversion is relatively insensitive to wavelength since the device contains no periodic structures. These devices are easier to fabricate than others containing periodic structures.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.86-89
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the resent work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section exclusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• 대한전자공학회논문지
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• 제23권2호
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• pp.149-169
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• 1986

Fundamentals of electrodynamics of moving sources with constant velocity in an anisotripic plasma when the do magnetic field and the relative motion are oriented in arbitrary directions are presented. The well-known Minkowski's relations are generalized to accomodate anisotropic and dispersive media, and relativistic transformation formulae of constitutive parameters are derived and expanded into polynomials of the speed ratio \ulcornerto increase the utility of the formulae. The helmholtz wave equation of electromagnetic fields is generalized to the media charactrized by tensor parameters, and is solved in operator form. Also the solution of wave equation is expressed as a porcuct of the inverse of the wave operator matrix and the source function vector, and the inverse of the wave operator matrix is presented in an explicit form. The equations and formulae derived in this paper are all general, and can be reduced to known and proven results upon imposing the restriction called for by specific situations.

• 반도체디스플레이기술학회지
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• 제3권1호
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• pp.31-34
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• 2004

We develop Mueller-matrix spectroscopic ellipsometry based on dual compensator configuration. This technique is very powerful for measuring surface anisotropy in nano-scale, especially when materials show depolarization. Dual-rotating compensator configuration is adopted with the rotational ratio of 5:3 originally developed by Collins et al[1]. The instrument can provide 250-point spectra over the wavelength range from 230 nm to 820 nm in one irradiance waveform with minimum acquisition time of Tc=10 s. In this work, the results obtained in transmission modes are presented for the initial attempt. We present calibration procedures to diagnose the system from the utilized data collected in transmission mode without sample. We expect that the instrument will have important applications in thin films and surfaces that have anisotropy and inhomogeneity.

• 소성∙가공
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• 제11권8호
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• pp.724-730
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the present work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section extrusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.911-917
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• 1998

In this paper, we have investigated the generation of pretilt angle for nematic liquid crystal (NLC) in a cell with oblique non-polarized ultraviolet(UV) light irradiation polyimide (PI) surface. It was found that the monodomain alignment of the NLC is obtained with an angle of incidence of 70∼85。 on PI surface. It is considered that the monodomain alignment of NLC is attributed to anisotropic of NLC is about 3。 with and angle of incidence of 70∼75。. Finally, we observed that the voltage-transmittance, response time, and voltage-holding-ratio(VHR) characteristics of photo-aligned twisted nematic(TN)-LCD with and angle of incidence of 85。 on PI surface were almost same compared to rubbing -treated TN-LCD.

• 한국전기전자재료학회논문지
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• 제15권9호
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• pp.818-821
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• 2002

We investigated the evolution of magnetic property with varying palladium (Pd) contents and elevating substrate temperatures up to 200 $^{\circ}C$ during dc-sputtering. We observed that saturation magnetization (Ms), remanence and anisotropic magnetoresistance (AMR) ratio decrease with Pd contents in the case of keeping the substrate temperature at 3$0^{\circ}C$. However they increase by adding 2 %Pd, then decrease above 3 %Pd when we keep the substrate temperature at 20$0^{\circ}C$. Coercivity does not change with Pd contents. Our results imply that we may tune the Ms and AMR with Pd contents and substrate temperature in permalloy films.

• 한국생산제조학회지
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• 제9권6호
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• pp.41-48
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• 2000

The Compression molding process is widely used in the automotive industry to produce parts that are large, thin, light-weight, strong and stiff. Compression molded parts are formed by squeezing a glass fiber reinforced polypropylene sheet, known a glass mat thermoplastic(GMT), between two heated cavity surfaces. In this study, the anisotropic viscosity of the Unidirectional Fiber-Reinforced Plastic Composites is measured using the parallel plastometer and the composites is treated as an incompressible Newtonian fluid. The effects of molding parameter and fiber contents ratio on longitudinal/transverse viscosity are also discussed.

• Journal of Magnetics
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• 제10권1호
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• pp.28-32
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• 2005

The magnetic properties and ordering behavior of Nb-doped FePt alloy films prepared by dc-magnetron sputtering were investigated. It was found that Nb addition retarded the ordering reaction from the disordered face-centered-cubic (fcc) Al phase to the ordered face-centered-tetragonal (fct) L1₀ phase. The tetragonality (c/a ratio) of the ordered fct L1₀ phase increased with the Nb concentration. Nb addition hampered c-axis contraction during ordering, probably because the larger Nb atoms occupy Pt sites. Consequently, the coercivity and magnetocrystalline anisotropic energy of Nb-doped FePt alloy films are lower than those of un-doped FePt film under equivalent annealing conditions.

• 한국초전도ㆍ저온공학회논문지
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• 제7권3호
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• pp.13-16
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• 2005

Multi-stacked HTS tapes are needed to conduct large current in the power application. In this paper magnetization losses of the multi-stacked YBCO coated conductor and the BSCCO tape have been measured and compared. Magnetization losses of single tape, 2-stacked, 3-stacked and 4-stacked HTS tapes have been presented in this paper. Multi-stacked tapes have been fabricated using face-to-face type stacking method. Measurements of magnetization loss were performed under various stacked of external magnetic field to consider the anisotropic characteristics of HTS tapes. Test results show that loss density per unit volume decreased for both YBCO coated conductors and BSCCO tapes when the stacking number of tapes is increased. As the external magnetic field decreased, the ratio of decrement has risen because the full penetration magnetic field(Bp) of the multi-stacked tape is larger than that of the single tape.