• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.49-50
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• 2011

Receiving sensitivity of the power gain by using Soret typed FZPL antenna should be worse when obliquely incident wave is illuminated on the FZPL. To solve this problem, elliptic Fresnel Zone Plate Lens antenna system should be introduced. Some numerical results computed by PO method are compared with Kirchhoff's approximation and measurement result.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.67-69
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• 2012

In this paper, electromagnetic scattering analysis of Fresnel Lens by using 2D FDTD method was performed. Fresnel lens which is consigured 7 diffracted conductors, and considered at 5GHz. As a result, axial gain characteristic corresponding to near design focusing distance at 0.71m is 26dB.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.1-7
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• 2006

A light guided plate coupled with the micro Fresnel lens array(MFTA) is designed to improve the efficiency of the LCD backlight unit. Blazed Frenel lens and binary multi-level Fresnel lens are adapted for the MFLA. This type of MFLA can replace the prism sheet and diffuser sheet which are used for the conventional type of the LCD backlight unit. The luminance and uniformity are calculated to verify the performance of the MFLA type LCD backlight unit.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.38-39
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• 2015

최근 고 해상도의 콘텐츠의 보급이 늘어나는데 이에 따라 암호화를 위한 계산 량과 시간이 증가하였다. 본 논문은 고 해상도의 콘텐츠에서 많은 양의 암호화 계산과 시간을 줄이기 위해 프레넬 변환을 이용한 암호화 방법을 제안하였다. 프레넬 변환을 통하여 획득한 회절 영상은 거리에 따라 가운데로 집중되는 특성을 가지는데, 고 해상도의 영상을 먼 거리에서의 회절 영상을 획득하여 가운데의 집중된 영역에 암호화를 수행하여 암호화 영역을 줄여 계산 량을 줄일 수 있다. 본 논문에서 제안하는 암호화 알고리즘을 구현하여 10m의 거리일 때 0.004%의 데이터만 암호화 하여 모든 데이터를 숨길 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.55-57
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• 2011

TLM method to analyize receiver gain characteristic of the FZPL antenna which is operated at 12GHz and can be applied to satellite TV system, radio telescope, and Geodetic System. Some numerical results computed by TLM method are compared with Kirchhoff's approximation and PO method. As a result, receiver gain characteristic on main axis of the 12GHz FZPL antenna is shown at the front side, which means that the focal length is 15% shorter than designed focal length.

• Applied Microscopy
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• v.32 no.2
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• pp.81-90
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• 2002

In this review, the author discussed how the Fresnel and Fraunhoffer Diffraction can be deduced from the Huygens-Fresnel principle and Kirchhoff Diffraction Theory. Fresnel diffraction became the basic theory of the CTEM image theory, and Fraunhoffer diffraction became the base for electron diffraction and HRTEM image theory by Fourier transformation. The author also discussed the diffraction based on Born series.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.15-18
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• 2003

Most numerical techniques such as FEM, BEM, and MOM are able to analize electromagnetic scattering problems from arbitrary shapes. Although these methods could be applied to compute electromagnetic scattering problems in frequency domain, it was limited for electrodynamic problem in time domain. In this paper, electromagnetic scattering problem from Fresnel zone plate lens are considered. Some numerical results computed by TLM are compared with Kirchhoff's approximation and PO method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.43-44
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• 2014

By using geometrical structure of Fresnel lens, it can be applied with receiver antenna and geodetic system. In this paper, we consider Soret typed fresnel lens with reflected plate and its focusing gain characteristics is calculated by the FDTD method.

• Korean Journal of Optics and Photonics
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• v.20 no.1
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• pp.1-5
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• 2009

Recently, much research has been done for to realizeing nano-scale photonic circuits based on photonic crystal, plasmonics and silicon photonics in order to overcome fundamental limits of electronic circuits. These limits include such as bottleneck of speed, and size that cannot be reduced. Even though several kinds of coupling schemes have been reported, coupling structures are still large when it is compared with the nano-scale optical circuit. In this paper, we proposed using a very thin Fresnel lens while shortening the focal length of the Fresnel lens as much as possible. We proposed, for the first time, to utilize metal slits that are able to use the optical coupling system between a nano-scale optical circuit and the standard single mode optical fiber for overcoming the limitation of focal length shortening of the Fresnel lens. Comparative study has been carried out with a FDTD simulation between normal and metal slit assisted Fresnel lens. From the result of simulation, we can achieve 65% coupling efficiency for the metal-slit Fresnel lens when the focal length of metal-slit Fresnel lens is just $4{\mu}m$. On the other hand, the coupling efficiency of the normal Fresnel lens is about 43%.

• Korean Journal of Optics and Photonics
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• v.33 no.1
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• pp.28-34
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• 2022

We study through computational simulation the focal performance of an infrared (IR) Fresnel lens, composed of a multilayer-graphene zone plate formed under a graphene electrode. Here the Fermi level E_F of the patterned multilayer graphene is adjusted by the overlying graphene electrode. The Fresnel lens effect, with respect to the reflectance contrast between the graphene electrode and the 8-layer graphene zone plate placed on a glass substrate, has been analyzed over a broad wavelength range from 4 to 30 ㎛. As the optimal wavelength of 8 ㎛ (considering the reflectance and the reflectance-contrast ratio) is incident upon the Fresnel lens with a focal length of 240 ㎛, the focal intensity is enhanced by a factor of 4.3 as the E_F of multilayer graphene increases from 0.4 eV to 1.6 eV, and is improved by a factor of 5.8 as the number of graphene layers increases from two to eight. As a result, an all-graphene-based IR Fresnel zone-plate lens, exhibiting multifocal function (240 ㎛ and 360 ㎛) according to the selected E_F, is proposed as an ultrathin lens platform.