• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.393-396
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• 2004

In this paper, multifrequency, polarimetric SAR data acquired during the first SIR-C/XSAR mission over the Seoul and Gyunggi-do (Korea) test sites are analyzed. The main objective of the study is to assess the possibility of extracting relevant information about surface properties for geophysical applications using polarimetry. This study analyses the characteristics of polarization responses and polarimetric parameters to conditions present in urban, river, agricultural, and forested areas. Results indicate that the dominant scattering property from these fields varies depending on the land cover types. The polarization response graphs and the backscattering coefficients associated with the polarimetric parameters are also useful in characterizing these cover types.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1893-1896
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• 2003

This research aimed to fabricate a micro structure using micro electrochemical machining (${\mu}$-ECM). with a view to that the theory of ${\mu}$-ECM is established accurately in a different way of conventional electrochemical machining. In details, if the impedance is existed in the system, it is difficult to analyze the micro electrochemical reaction efficiently in polarization curve using a potentiodynamic test. Hence, this research investigates the relationships between impedance and electric current measuring with a potentiostatic test applying to a pair or electrode as a constant potential. And this paper examines the influence of temperature of electrolyte on polarization curve for the quantitative analysis of electrochemical reactions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.111-117
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• 2014

With the development of technology, the display industry has been focusing on the development of new types of displays, such as bendable and wearable displays. However, the PVA/TAC polarizing film used in the manufacturing of a normal display is associated with low luminance and low efficiency. If the existing polarization film is replaced with a wire grid polarizer, it is possible to reduce the thickness significantly. Moreover enhanced brightness can also be expected. This study confirms the optical properties of the WGP through a simulation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.7-14
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• 1997

A rigorous analysis method of electromagentic scattering from frequency selective surface with gridded square loop elements in case of oblique incident and arbitrary polarization is presented, which uses the roof-top subdomain basis function. The frequency response and polarization characteristics of the reflected wave and the transmitted wave for various widths of the grid and the conductor square loop, and for the various gaps between the grid and the conductor square loop, and for the various gaps between the grid and square loop is investigated. To confirm the validity of presented method, frequency selective surfaces with gridded square loop elements are fabricated with honeycomb structures, calculate dvalues for the frequency response of the reflected wave and the transmitted wave for arbitrary incident angle and polarization are compared with measured values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1741-1746
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• 2001

This paper proposes the OFDM system that uses circularly polarized waves for improving the system performance. The circular polarization has the characteristic that it cannot receive the waves which are reflected by odd times. Using this characteristic, a modified OFDM system that uses the cross-handed circular polarization(XCP-OFDM) is newly proposed. By using the characteristic of circular polarization, it is clearly seen that the system performance of XCP-OFDM can be improved to a great extent. This is due to a reduction of the interferences caused by reflected waves and inter-channel interference. Both theoretical analysis and system simulation results are described.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.63-66
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• 2008

This study presents 0-dimensional model for solid oxide fuel cells(SOFCs). The physics of the cell and the simplifying assumptions are presented, and only hydrogen participates in the electrochemical reaction. The electrical potential is predicted using this model. The Butler-Volmer equation is used to describe the activation polarization and the exchange current density is changed according to the partial pressure of reactants and the temperature. The electrical conductivities of electrodes and an electrolyte are calculated for the ohmic polarization. Material characteristics and temperature affect those factors. Analysis of concentration polarization based on transport of gaseous species through porous electrodes is incorporated in this model. Both binary diffusion and Knudsen diffusion are considered as the diffusion mechanism. For validation, simulation results at this work are compared with our experimental results and numerical results by other researchers.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.214-223
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• 2013

This paper proposes a theoretical analysis of hidden device detection and a design of multiband circular polarization patch array antenna for non-linear junction detector system application. A good axial ratio of circular polarization patch antenna is realized by a new approach that employs inclined slots, two rectangular grooves and a truncated ground for the conventional antenna. A good axial ratio of the 1.5 dB lower is measured by having an asymmetric gap distance between the ground planes of the coplanar waveguide feeding structure. The common ground plane of the linear array has an optimum trapezoidal slot array to reduce the mutual coupling without increasing the distance between the radiators. The higher gain of about 1 dBi is realized by using the novel common ground structure. The measured return loss, gain, and axial ratio of the proposed single radiator, as well as the proposed array antennas, showed a good agreement with the simulated results.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.43.3-43.3
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• 2019

Magnetic fields play an important role in supporting molecular clouds against gravitational collapse. The measured magnetic field strengths in molecular clods enable us to see the effect of magnetic fields in star-forming regions. People have used the Chandrasekhar and Fermi (CF) method to estimate magnetic field strength from observational quantities of molecular cloud density, turbulent velocity and polarization angle dispersion. However, previous studies obtained just one magnetic field strength over the quite large region of a molecular cloud by using the CF method. We here suggest a way to estimate magnetic field strength distribution in Orion A region. We used 450 and 850-micron polarization data of James Clerk Maxwell Telescope (JCMT). Magnetic field strengths were estimated in two wavelengths with 4 pixel resolutions of 16, 20, 24 and 28". Through statistical analysis, we proved the difference of magnetic field strengths between two wavelengths were caused by the difference of their beam sizes. Additionally, we calculated the radii of curvature of polarization segments to select a best pixel resolution for estimating the magnetic field distribution. The pixel resolution should be larger than a radius of curvature. We selected that 20 or 24" pixel resolutions are good choices towards Orion A region.

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.45-52
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• 2021

The surveillance camera market has developed and plays an important role in the field of video surveillance. However, in recent years, the identification of areas requiring surveillance has been limited by reflective light in the surveillance camera market. Cameras using polarization filters are being developed to reduce reflective light and facilitate identification. Programs are required to automatically adjust polarization filters. In this paper, we proposed an optimal angle extraction method from surveillance cameras using polarization filters through histogram analysis. First of all, transformed to grayscale to analyze the specifications of frames in multiple polarized angle images, reducing computational throughput. Then we generated and analyzed a histogram of the corresponding frame to extract the angle when the highlights are the fewest. Experiments with 0˚ and 90˚ showed high performance in extracting optimal angles. At this point, it is hoped this technology would be used for surveillance cameras in place like beach with a lot of reflective light.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.638-645
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• 2015

Vanadium redox flow batteries (VRFBs) have been investigated for their potential utility as large energy storage systems due to their advantageous performances in terms of long cycle life, high energy efficiency, low cost, and flexible design. Carbon materials are typically used as electrodes in redox reactions and as a liquid electrolyte support. The activities, surface areas, and surface morphologies of porous carbon materials must be optimized to increase the redox flow battery performance. Here, to reduce the resistance in VRFBs, surface-modified carbon felt electrodes were fabricated, and their structural, morphological, and chemical properties were characterized. The surface-modified carbon felt electrode improved the cycling energy efficiencies in the VRFBs, from 65% to 73%, due to the improved wettability with electrolyte. From the results of impedances analysis with proposed fitting model, the electrolyte-coupled polarization in VRFB dramatically decreased upon modification of carbon felt electrode surface. It is also demonstrated that the compressibility of carbon felt electrodes was important to the VRFB polarization, which are concerned with mass transfer polarization. The impedance analysis will be helpful for obtaining better and longer-lived VRFB performances.