• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.8
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• pp.448-454
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• 2004

In this paper, circular polarized antennas of Tx 30GHz and Rx 20GHz are implemented in LTCC process. Tx antenna has a circular patch structure and Rx antenna has a ring patch structure. The feeding line of Tx antenna is placed in the center hole of Rx ring patch antenna which is printed under Tx circular patch antenna layer. It makes antenna size smaller. Tx antenna's return loss in under -l0dB level from 30GHz to 31GHz and Rx antenna is under -10 dB from 20GHz to 21GHz. The isolation between two antennas is less than -20dB. Axial ratio is less than 3dB thoughout each band.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.59-62
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• 1994

Tact Electrical conductivity. optical absorption spectra of poly(p-phenylene vinylene) and their dependence on stretching are discussed in detail. The conductivity in the parallel direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching. The photocurrent spectrum for the ligh polarized parallel to the chain direction is much enhanced in lower photon energy compared with that for the light polarized perpendicular to that direction. The result may be originated in the difference of energies which is needed to photogenerate carriers wi th the light polarized parallel and perpendicular to the chain stretched direction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.150-152
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• 2005

We investigated the fabrication and characteristics of spin-polarized LEDs based on GaN using (Ga,Mn)N as spin injection source. (Ga,Mn)N thin films were found to exhibit the ferromagnetic ordering above room temperature and the negative MR up to room temperature. The electrical characteristics in spin LEDs did not degraded in spite of the insertion of (Ga,Mn)N films. In EL spectra of spin LEDs, it is confirmed that spin LEDs emit the strong light at 7 K as well as room temperature. These results suggest that it is possible to emit spin-polarized light in our spin LEDs.

• Communications for Statistical Applications and Methods
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• v.17 no.6
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• pp.767-777
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• 2010

This paper investigates the relationship between the passenger car demand and business activities in the OECD. The positively linear relationships changed suddenly since 1990 and the reason was thought to be the polarized economic development of USA and Japan. The cases of other countries supports this conclusion. According to the conclusion, we modeled and estimated the car demand function of Korea.

• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.271-275
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• 2001

We investigated H-type molecular aggregation in a simply spin-coated amorphous homopolymer film of polymethacrylate containing push-pull azobenzene moieties. It was found that the aggregate formation was strongly influenced by thermal treatment an d that the aggregate created in the polymer film could be easily disrupted by irradiation of a linearly polarized light. In the first writing cycle of aggregated polymer film, photo-induced birefringence showed a steep increase to the highest value followed by a gradual decrease to the certain asymptotic value under longer irradiation of a linearly polarized light. This unique behavior could be attributed to the cooperative motion and the disruption of the aggregated molecules under continuous irradiation of light.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1458-1465
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• 2018

We present a constructed setup for polarizing $^{129}Xe$ noble gas. Hyperpolarized $^{129}Xe$ has been obtained via spin exchange with an optically pumped rubidium vapor. Optical pumping is based on polarizing the valence electron of rubidium by the resonant absorption of a circularly polarized laser light. The magnetic field of 30 G was used for obtaining $^{129}Xe$ polarization. The apparatus for detecting polarization is a nuclear magnetic resonance spectrometer. The highest $^{129}Xe$ polarization of 54% has been obtained using 60 W circularly polarized laser light with wavelength of 794.7 nm. The measured longitudinal relaxation time of the hyperpolarized $^{129}Xe$ was 72.3 minutes.

• Current Optics and Photonics
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• v.5 no.1
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• pp.72-76
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• 2021

The polarized micro-photoluminescence spectrum was analyzed to investigate the anisotropic localized states in a single GaAs quantum ring. An energy difference of ~0.1 meV was observed from the perpendicularly polarized spectrum measured by a pair of linear analyzers. Spectral dependence of the polarized emission was also characterized in terms of rotation and ellipticity angles using four Stokes parameters. While the rotation angle indicates the symmetric axis of an anisotropic quantum ring with a small variation (± 2°), the ellipticity angle varies from 7.4° down to -2.5°. We conclude that optical anisotropy and birefringence are induced by the crescent-like lateral shape of localized states.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.55-61
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• 2021

In this paper, we proposed and implemented defect detection methods of polarized film with half-wave phase retardation plates. We investigated the principles of phase retardation compensation and optical principle of half-wave phase retardation plates. We analyzed of samples of polarized film with half-wave phase retardation plates. The optical defect detection methods are proposed and the performance is validated with experiments.

• Current Optics and Photonics
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• v.7 no.2
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• pp.147-156
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• 2023

Circularly polarized (CP) emission can be achieved by integrating emissive materials into chiral metasurfaces. Such CP light sources in integrated device platforms are desirable for important potential applications. However, the exact characterization of the polarization state in CP emission may include some errors because of the unwanted polarization distortion caused by optical components (e.g., beam splitter) in the optical setup. Here, we consider CP emission measurements from chiral metasurfaces and characterize the polarization distortion caused by the beam splitter. We first detail the procedures for the Stokes parameters and Mueller matrix measurements. Then, we directly measure the Mueller matrix of the beam splitter and retrieve the original polarization state of CP emission from our metasurface sample. Using the measured Mueller matrix of the beam splitter, we specifically identify what contributes to polarization distortion in CP emission. Our work may provide useful guidelines for the characterization and compensation of polarization distortion in general Stokes parameter measurements.

• Current Optics and Photonics
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• v.8 no.2
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• pp.192-200
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• 2024

Wheat stripe rust, caused by Puccinia striiformis, has reduced winter wheat yield globally for ages. In this work, multi-spectral Mueller matrix imaging with 37 measurements using the method of double rotatable quarter-wave plates was used to investigate wheat stripe rust. Individual Mueller matrix measurements were performed on incident monochromatic light with nine bands in the range of 430 to 690 nm. As a result, it was found that the infected area absorbed linearly polarized light and was sensitive to circularly polarized light in the spectral domain. Both linear depolarization and linear diattenuation images distinguished between wheat stripe rust and healthy tissue. The responsiveness of stripe rust to polarized light reveals the potential of using polarization imaging to detect plant diseases. This further suggests that the multi-spectral Mueller matrix imaging system provides us with an alternative approach to agricultural disease detection.