• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.34-39
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• 2017

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.16-24
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• 2007

The high-frequency analysis method of back-scattering cross section spectrum of rotating targets is established. The time history of the back-scattering cross section is calculated using a quasi-stationary approach, based on a physical optics and a physical theory of diffraction, combining an adaptive triangular beam method to consider the shadow effect. And the spectra of back-scattering cross section by the Doppler effect are analyzed applying a simple fast Fourier transform method to its time history. The numerical calculation for rotating targets, such as rotating metal plates and underwater propeller, are carried out. The time history appears to be periodic with respect to the number of wings. The backscattering cross section spectrum level and its frequency shift are dependent on the rotating speed, direction, and the shape of the targets.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.536-544
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• 2009

The performance of radars operated near an offshore wind farm region may be degraded due to the distorted signals by wind turbines. This degradation of radar systems includes ghost effects and doppler effects by a tower, nacelle, and turbine blades consisting of the wind turbine. In this paper, electromagnetic wave backscatterings from a offshore wind turbine are numerically simulated in terms of temporal radar cross section and radar cross section spectra, using a quasi-static approach based on physical optics and physical theory of diffraction. The simulations are carried out at 3.05 GHz for the seven yaw angles and four blade pitch angles. From the results, radar cross section values and doppler effect as turbine blades rotate are investigated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.929-938
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• 2000

A summary of the development and verifications of a computer code being developed at Pohang University of Science and Technology (POSTECH) for calculating the radar cross section(RCS) of complex targets is presented. The complex targets are modeled in terms of patches and wedges. This code utilizes physical optics, physical theory of diffraction and shooting and bouncing rays method to calculate the RCS of complex targets. For the verification of the RCS prediction code, a simple-shaped scale-model was manufactured and the RCS was measured at the POSTECH compact range. The obtained RCS was processed to give frequency-domain RCS patterns and ISAR images. The predicted RCS shows good agreement with measured one. The RCS prediction methods presented here are applicable to stealth design and target recognition.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.260-266
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• 1997

Holographic optical elements for polarization separation (HPS) are fabricated in a dichromated gelatin(DCG) thin film of 7${\mu}{\textrm}{m}$ thickness. The polarization properties of HPS is characterized by measuring diffraction efficiency with several physical parameters like exposure time, incident angle and read-out polarization angles. The experimental data are compared with theoretical results based on Kogelnik's coupled wave theory, which shows good agreement. It is also found that the HPS element has a very high extinction ratio of polarization over 500:1 for S and P polarizations, respectively, with He-Ne laser wavelength. We also propose an optical switch optical interconnects by using HPS elements.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.261-267
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• 2015

The eigenvalue problems involving the diffraction of waves by multi-layered grating configurations can be explained by rigorous modal expansion terms. Such a modal solution can be represented by equivalent transmission-line networks, which are generalized forms of simple conventional circuits. This approach brings considerable physical insight into the grating diffraction process of the fields everywhere. In particular, the transmission-line representation can serve as a template for computational algorithms that systematically evaluate dispersion properties, radiation effects and other optical characteristics that are not readily obtained by other methods. To illustrate the validity of the present rigorous approach, the previous research works are numerically confirmed and the results agree well each other.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.7
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• pp.584-587
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• 2017

In this paper, the radar cross section of the integrated mast module for battleship is analyzed. The computation program based on physical optics and physical theory of diffraction is developed and the computed results are compared with those of commercial simulator to check the accuracy of computations. The radar cross section is calculated in terms of the mast shape, incident angle, and polarization. The radar cross section can be reduced through the change of the mast slope and the chamfered mast, which can be applied to a mast with a low radar cross section.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.5
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• pp.463-470
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• 2016

In this paper, we introduce a method of scattering centers extraction using the polarimetric data. VIRAF software based on the PO (Physical Optics) and PTD(Physical Theory of Diffraction) were used to calculate the surface scattering and the edge or wedge scattering, respectively. In addition, by using the unitary transformation, 4-channel data based on the linear polarization basis were converted to 2-channel data based on the left/vertical-circular polarization basis, leading to data compression coherently. The scattering mechanism was analyzed in terms of the polarization states and different look angles by using the scattering center of a target extracted by the 2D RELAX algorithm.