• Current Optics and Photonics
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• v.3 no.4
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• pp.275-284
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• 2019

Chirality is ubiquitous in physics and biology from microscopic to macroscopic phenomena, such as fermionic interactions and DNA duplication. In photonics, chirality has traditionally represented differentiated optical responses for right and left circular polarizations. This definition of optical chirality in the polarization domain includes handedness-dependent phase velocities or optical absorption inside chiral media, which enable polarimetry for measuring the material concentration and circular dichroism spectroscopy for sensing biological or chemical enantiomers. Recently, the emerging field of non-Hermitian photonics, which explores exotic phenomena in gain or loss media, has provided a new viewpoint on chirality in photonics that is not restricted to the traditional polarization domain but is extended to other physical quantities such as the orbital angular momentum, propagation direction, and system parameter space. Here, we introduce recent milestones in chiral light-matter interactions in non-Hermitian photonics and show an enhanced degree of design freedom in photonic devices for spin and orbital angular momenta, directionality, and asymmetric modal conversion.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.240-244
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• 2002

We proposed a novel temperature sensor based on the phenomena that the phase difference between principal polarization states in an optical retarder is a function of temperature. The polarization state of an optical beam is changed as it passes through the optical retarder, with the change dependent on the temperature. The temperature of the optical retarder is determined by comparison of the power difference between principal polarization states. A temperature sensor was successfully implemented using a polarization maintaining fiber of length 100 mm as the optical retarder. The change rate of phase difference on temperature was 0.236$^{\circ}C$$_{-1}$ and the measurement error was $\pm$0.038$^{\circ}C$ over the temperature region of -2.6$^{\circ}C$~3.4$^{\circ}C$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3054-3067
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• 2015

The phenomena of higher channel cross polarization discrimination (XPD) is mainly observed for future wireless technologies such as small cell network and massive multiple-input multiple-output (MIMO) system. Therefore, utilization of high XPD is very important and space-polarization division multiple access (SPDMA) with dual-polarized MIMO system could be a suitable solution to high-speed transmission in high XPD environment as well as reduction of array size at base station (BS). By SPDMA with dual-polarized MIMO system, two parallel data signals can be transmitted by both vertically and horizontally polarized antennas to serve different mobile stations (MSs) simultaneously compare to conventional space division multiple access (SDMA) with single-polarized MIMO system. This paper analyzes the performance of SPDMA for maximum ratio transmission (MRT) in time division duplexing (TDD) system by proposed dual-polarized MIMO spatial channel model (SCM) compare to conventional SDMA. Simulation results indicate that how SPDMA utilizes the high XPD as the number of MS increases and SPDMA performs very close to conventional SDMA for same number of antenna elements but half size of the array at BS.

• Journal of the Korean Society of Visualization
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• v.13 no.2
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• pp.16-21
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• 2015

Concentration polarization(CP) phenomena show great potential on desalination technology. As we can control the dimension of silicon based nanochannel system, it can be used to model ion exchange membrane. In this study, to investigate the effect of nanochannel number and working conditions on the CP based desalination process, nanochannel based microfluidic system is fabricated. First, we optimized nanochannel number and working conditions to conduct visualization study on CP based desalination process. Second, we visualized the desalination process with fluorescent dye in the desalination chip. We also visualized that the particles also can be removed by the CP based desalination process.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.5-9
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• 2001

A wavemeter was realized using the phenomena that the phase lag between principal polarization states in an optical retarder is a function of wavelength. The change in the polarization state of the optical beam as it passes through the optical retarder is dependent on wavelength. The wavelength of the optical beam is determined by comparing the power difference between principal polarization states. A prototype wavemeter was successfully implemented using a polarization maintaining fiber with birefringence $3\times10^{-4}$ and length 100 mm as the optical retarder. The measurement resolution was 0.08 nm over a wavelength region of 1554.38 nm-1557.l9 nm, which agreed well with theoretically calculated results. In addition, the dependence of operating characteristics on temperature was analyzed theoretically and experimentally.mentally.

• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1070-1077
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• 1998

Effect of current collecting layer on the cathode was characterized by AC impedance spectroscopy at 800$^{\circ}C$ under flowing air. LSM-YSZ composite cathode showed lower polarization resistance due to the in-crease of triple phase (LSM/YSZ/Pore) boundary length by incorporation of YSZ. Ohmic resistance {{{{ {R }_{1 } }} of LSM-YSZ was higher than that of pure LSM however because in-plane resistance of the cathode was fair-ly high due to its high specific resistivity. To reduce the in-plane resistance of LSM-YSZ cathode cathode side current collecting layer was required. Ohmic resistance {{{{ {R }_{1 } }} was reduced after forming LSM current col-lecting layer on the LSM-YSZ cathode. In case of pure LSM cathode the formation of Pt, or LSCO current collecting layer reduced polarization resistance {{{{ {R }_{p } }} but ohmic resistance {{{{ {R }_{1 } }} was relatively constant. After annealing of LSM cathode with Pt current collector at higher temperature polarization resistance {{{{ {R }_{p } }} was in-creased but ohmic resistance {{{{ {R }_{1 } }} was constant. These phenomena indicate that Pt or LSCo current col-lecting layers act as a catalytic layer for oxygen reduction of pure LSM cathode. LSCO current collector was effective in reducing the ohmic and polarization resistance of LSM-YSZ cathode.

• 한국사회정책
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• v.20 no.2
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• pp.261-304
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• 2013

This article is aiming intensively to analyze the polarizing tendency of labour market and social integration. The polarization of labour market is being regarded as one of the hottest issues not less important than those problems of economic growth, employment, income distribution and national security etc. in the national policy. In this article, we will first follow up the important phenomena of labour market polarization and the background as well as its consequence. Especially, it asks if the present labour policy in the new government which is now being concentrated on the improvement of employment rate(from the present 63% to the 70% in the future) could deserve to diminish the polarization of labour market in korea. At one side, this article makes the special attention on the diversifying tendency of labour market and the various phenomena of fragmentation and segmentation in the labour market according to the forms and types of employment and according to the employee's status as much as the company's size. At the other side, it emphasizes that to overcome the polarization of labour market should require the wide reform from the legal measure to the improvement of the wage system, and the qualification system and the social investment as well as the human resource development. Furthermore, this article stresses the importance of integrative approach between the active market policy and the social policy instead of choosing each policy option, seperatively.

• Advances in materials Research
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• v.4 no.2
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• pp.113-132
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• 2015

The phenomena of high-voltage polarization and conductivity in oriented vinylidenefluoride and tetrafluoroethylene copolymer films have been investigated. It was shown that under certain electric fields, injection of carriers from the material of electrodes appears The barrier for holes injection in the copolymer was found to be lower than that for electrons. It results in more effective screening of the external field near the anode than near cathode. Electrones, ejected from cathode, creating negative charge by trapping on the surface. It is shown that the electrons injected from cathodes create a negative homocharge on the copolymer surface and then become captured on the surface shallow traps. Their nature has been studied by the x-ray photoelectron spectroscopy. It was shown that these traps may consist of chemical defects in the form of new functional groups formed by reactions of surface macromolecules with sputtered atoms of aluminum. The asymmetric shape of hysteresis curves was explained by the difference in mobility of injected holes and electrons. These factors caused appearance of "non-closed" hysteresis curves for fluorine-containing polymer ferroelectrics. Hysteresis phenomena observed at low electric fields (below coercive ones) are to associate with the behavior of the domains localized in the ordered regions formed during secondary crystallization of copolymers.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.679-686
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• 2018

Reverse osmosis (RO) concentration of sodium chloride, sodium acetate, and sodium citrate solutions has been performed by polyamide RO membrane. Concentration polarization phenomena was also studied by changing pressure, solute kinds, and initial solution concentration. Pressure effect on permeation flux was that the increase of flux was accompanied by the increase of pressure. Flux increase was observed by the decrease of initial solution concentration. Surface concentration on the RO membrane increases and so flux declines due to the concentration polarization. In the later phase of concentration, concentration polarization effect was decreased by the back diffusion of solute from the polariztion layer. In case of sodium citrate, its large ion size and charge density resulted in the discrepancy between theory and experimental data of concentration polarization. It may be due to electric repulsion on the membrane surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.2
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• pp.139-144
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• 2001

In this study, we have investigated the photoinduced birefringence of Ag plarized-photodoping in double-layer of Ag doped chalcognide thin films and dependence of polarization states in chalcogenide thin films. Also, we have investigated the polarization dependence of photoinduced birefringence and the anisotropy of absorption in an amorphous As$\sub$40/Ge$\sub$10/Se$\sub$15/S$\sub$35/ chalcogenide thin films using two 632.8nm He-Ne lasers, which have a smaller energy than the optical energy gap (E$\sub$OP/) of the film, i.e., an exposure of sub-bandgap light (hν$\sub$op/). The photoinduced phenomena of Ag polarized-photodooping increasing the linear dichroism(d), about 84% and birefringence(Δn), about 23%. It will offer lots of information for the photodoping mechanism and analysis of chalcogenide thin films.