• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1102-1109
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• 2006

In this paper, the polarization of piezoelectric materials is considered to improve actuation since the piezoelectric polarization has influences on the performance of the actuator. The topology design of compliant mechanism can be formulated as an optimization problem of material distribution in a fixed design domain and continuous approximation of material distribution (CAMD) method has demonstrated its effectiveness to prevent the numerical instabilities in topology optimization. The optimization problem is formulated to maximize the mean transduction ratio subject to the total volume constraints and solved using a sequential linear programming algorithm. The effect of CAMD and the performance improvement of actuator are confirmed through Moonie actuator and PZT suspension design.

• Journal of the Korean Geophysical Society
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• v.5 no.4
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• pp.321-328
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• 2002

Difficulties encountered in downhole S-wave (shear wave) surveys include the precise determination of shear wave travel times and determination of geophone orientation relative to the direction of polarization caused by the seismic source. In this study an S-wave enhancing and a principal component analysis method were adopted as a tool for determination of S-wave arrivals and the direction of polarization from downhole S-wave survey data. An S-wave enhancing method can almost double the amplitudes of S-waves, and the angle between direction of polarization and a geophone axis can be obtained by a principal component analysis. Once the angle is obtained data recorded by two horizontal geophones are transformed to principal axes, yielding so called scores. The scores gathered along depth are all in-phase, consequently, the accuracy of S-wave arrival picking could be remarkably improved. Applying this processing method to the field data reveals that the test site consists of a layered ground earth structure.

• Journal of The Korean Astronomical Society
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• v.56 no.1
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• pp.23-33
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• 2023

We investigate the diffusion process of Thomson-scattered line photons in both real space and frequency space through a Monte Carlo approach. The emission source is assumed to be monochromatic and point-like embedded at the center of a free electron region in the form of a sphere and a slab. In the case of a spherical region, the line profiles emergent at a location of Thomson optical depth τ_Th from the source exhibit the full width of the half maximum σ_λ ≃ τ^1.5_Th. In the slab case, we focus on the polarization behavior where the polarization direction flips from the normal direction of the slab to the parallel as the slab optical depth τ_Th increases from τ_Th ≪ 1 to τ_Th ≫ 1. We propose that the polarization flip to the parallel direction to the slab surface in optically thick slabs is attributed to the robustness of the Stokes parameter Q along the vertical axis with respect to the observer's line of sight whereas randomization dominates the remaining region as τ_Th increases. A brief discussion on the importance of our study is presented.

• ETRI Journal
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• v.18 no.4
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• pp.287-299
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• 1997

Integrated-optic polarization controlling devices such as polarizers, polarization splitters, and polarization converters, are proposed and demonstrated in nonlinear optic polymers. Poling-induced birefringence in electro-optic polymers is exploited to fabricate the devices. The polymeric waveguide polarizers show low excess losses, and extinction ratios of 20.7 dB and 17.1 dB for TM-pass and TE-pass polarizers, respectively. The polymeric waveguide polarization splitters exhibit TE-TM mode splittings with crosstalk of 14.2 dB and 10.1 dB for TM and TE mode splittings, respectively. The polymeric waveguide polarization converters show successful TE/TM polarization mode conversion with conversion efficiencies of higher than 30 dB. The device employs poling-induced waveguides which have slowly rotating azimuth angle of optic axis along the light propagation direction. The novel polarization converter is insensitive to wavelength and easier to fabricate than the other polarization converters containing periodic structures.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.1
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• pp.43-50
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• 2000

In this study, experiments were carried out to measure the variations in the corrosion potential and current density of polarization curves using polycarbonate. The results were particularly examined to identify the influences affecting the corrosion potential including various conditions such as temperature, pH, catalytic enzyme, and salt. The lines representing the active anodic dissolution were only slightly shifted in the potential direction by temperature, pH, enzyme, and salt. The tafel slope for the anodic dissolution was determined based on the polarization effect with various conditions. The slope of the polarization curves describing the active-to-passive transition region were noticeably shifted in direction. Also, from the variation in the conditions, the optimum conditions were established for the most rapid transformation, including temperature, pH, corrosion rate, and resistance of corrosion potential. The second anodic current density peak and maximum passive current density were designated as the critical corrosion sensitivity(Ir/If). The value of Ir/If was then used in measuring the extent of the critical corrosion sensitivity of the polycarbonate. The potentiodynamic parameters of the corrosion were obtained using a Tafel plot.

• Journal of Information Display
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• v.8 no.4
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• pp.10-14
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• 2007

LCD performance is generally evaluated in terms of luminance and color versus viewing angle. In the present paper, we show that this type of display can be favorably characterized in terms of polarization. We show that ELDIM EZContrast instrument which is routinely used for viewing angle measurements can be upgrade for measuring the polarization state of the light at each incidence and azimuth angle. More precisely, the degree of polarization of light, its ellipticity and polarization direction can be measured at each incidence angle between 0 and $88^{\circ}$ and for all the azimuth angles (from 0 to $360^{\circ}$). Important differences between the displays can be detected and related to their internal structures when luminance and color profiles are quite similar. The same setup can also be used to characterize optical components of the LCDs.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1523-1526
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• 2009

We present highly polarized light emissions from an OLED on a flexible photonic anisotropic substrate. It was found that the polarization direction of emitted electroluminescent light corresponded to the ordinaryaxis of the photonic anisotropic substrate. Furthermore, it was also found that luminous polarized electroluminescence over 4,500 cd/$m^2$ was produced with high peak efficiency of 6 cd/A and high polarization ratio over 25.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.256-262
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• 2012

We derive the point-spread function of the reconstructed image from a point-source complex hologram, which includes phase error caused by polarization components, in the longitudinal direction of the point-spread function and analyze the effect of the error sources of polarization components having influence on image reconstruction of a point-source complex hologram in incoherent triangular holography.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.70-75
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• 2014

Permanent magnets have recently been considered as device that can be used to control the behavior of mechanical systems. Neodymium magnets, a type of permanent magnet, have been used in numerous mechanical devices. These are permanent magnets made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. The magnetic selection, magnet core design and mechanical errors of the magnetic component can affect the performance of the magnetic force. In this study, the coercive force, residual induction, and the dimensions of the design parameters of the magnet core are optimized. The design parameters of magnet core are defined as the gap between the magnet and the core, the upper contact radius, and the lower thickness of the core. The force exercised on a permanent magnet in a non-uniform field is dependent on the magnetization orientation of the magnet. Non-uniformity of the polarization direction of the magnetic has been assumed to be caused by the angular error in the polarization direction. The variation in the magnetic performance is considered according to the center distance, the tilt of the magnetic components, and the polarization direction. The finite element method is used to analyze the magnetic force of an optimized cylindrical magnet.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.35-38
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• 2006

The polarized direction of MT field was analyzed using the MT dataset measured in the Korean Peninsula. The atmospherics above 1 Hz has a large dispersion of polarized direction, whereas the Schumann resonance near 8 Hz exhibits the predominant direction ranging from $N20^{\circ}W$ to NS. The electromagnetic field variations below 0.1 Hz, induced by magnetic pulsations, show a strongly polarized direction of nearly NS. It results from the regular pulsations since the regular pulsation fields, driven by Alfv.n's wave in the magnetosphere, has a worldwide predominant direction of NS. The MT field strongly polarized along NS direction causes the poorly behaved XY impedance.