• Current Optics and Photonics
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• 제2권6호
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• pp.629-634
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• 2018

A broad dual-band terahertz metamaterial filter with sharp out-of-band rejections is designed and demonstrated. The center frequencies of the first and the second bands occur at 0.35 THz and 0.96 THz with 3 dB relative bandwidth of 31% and 17%, respectively. Results are measured using a THz time-domain spectroscopy system that shows agreement with simulations. Physical mechanisms of the broad dual-band resonance are clarified based on transmissions of different structures and surface current density distributions. Influence of structure parameters on the transmission characteristics are discussed. Symmetry of the structure ensures the filter polarization independence at normal incidence. These results supported by the design of the filter could find applications in broad multi-band sensors, terahertz communication systems, and other emerging terahertz technologies.

• Bulletin of the Korean Chemical Society
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• 제12권5호
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• pp.515-517
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• 1991

The electronic behavior of a organic metal $(BEDT-TTE)_2$${Cu_5}{I_6}$ observed to be stable at low temperatures was examined by performing tight-binding band electronic structure calculations. The suppression of a metal-insulator tansition is likely to originate from its quasi-two-dimensional Fermi surface with no nesting, in agreement with experiment.

• 대한전자공학회논문지TC
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• 제46권9호
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• pp.60-65
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• 2009

본 논문에서는 대역통과 여파기와 대역저지 여파기를 하나의 구조로 합성하여 크기 증가 없이 초광대역 특성을 가지면서 Wireless-LAN 대역을 저지하는 대역통과 여파기를 설계, 구현하였다. 대역저지 특성을 얻으면서도 여파기의 크기증가가 없어야 하기 때문에 전송선에 내장된 형태의 오픈 스터브를 사용하였다. 그리고 저역 통과 특성을 얻기 위하여 접지 면에 식각할 수 있는 DGS(Defected Ground Structure) 구조를 이용하였다. 기존의 대역통과 여파기와 저역통과 여파기를 직접 연결하였을 때 보다 크기를 줄일 수 있었다. 측정결과 통과대역은 $2.21GHz{\sim}10.92GHz$ 이고 삽입손실은 최대 0.7dB, 반사손실은 최소 17dB, 군 지연 변화폭은 0.22ns였으며 $5.3GHz{\sim}5.7GHz$의 저지대역을 형성하였다.

• Nuclear Engineering and Technology
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• 제34권3호
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• pp.202-210
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• 2002

The details of the electronic structure of the perfect crystal provides a critically important foundation for understanding the various defect states in uranium dioxide. In order to understand the local defect and impurity mechanism, the calculation of electronic structure of UO$_2$ in the one-electron approximation was carried out, using a semi-empirical tight-binding formalism(LCAO) with and without f-orbitals. The energy band, local and total density of states for both spin states are calculated from the spectral representation of Green’s function. The bonding mechanism in Perfect lattice of UO$_2$ is discussed based upon the calculations of band structure, local and total density of states.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.623-628
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• 2002

A meshfree formulation for the calculation of energy band structure is presented. The conventional meshfree shape function is modified to handle the periodicity of Bravais lattice, and applied to the calculation of real-space electronic-band structure. Numerical examples include the Kronig-Penney model potential and the empirical pseudopotentials of diamond and zinc-blonde semiconductors. Results demonstrate that the meshfree method be a promising one as a real-space technique for the calculations of diverse physical band structures.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.267-267
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• 2010

The continuous change in the electronic band structure of metal-adsorbed bilayer graphene was calculated as a function of metal coverage using first-principles calculations. Instead of modifying the unit cell size as a function of metal coverage, the distance between the metal atoms and bilayer graphene in the same $2{\times}2$ unit unit cell was controlled to change the total charges transferred from the metal atoms to bilayer graphene. The validity of the theoretical method was confirmed by reproducing the continuous change in the electronic band structure of K-adsorbed epitaxial bilayer graphene, as shown by Ohta et al. [Science 313, 951 (2006)]. In addition, the changes in the electronic band structures of undoped, n-type, and p-type bilayer graphene were studied schematically as a function of metal coverage using the theoretical method.

• 대한전자공학회논문지TC
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• 제41권1호
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• pp.65-68
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• 2004

본 논문에서는 밀리미터파 대역 전력증폭기가 출력단에 PBG (photonic bandgap structure) 구조를 설치함으로써 성능개선 되었다 PBG 구조는 Ka 대역에서 저역통과 특성을 갖도록 최적화되었다. 전력증폭기의 하모닉은 PBG 구조에 의하여 억제되었고 50 GHz에서 40dBc 개선되었다 전력증폭기의 IMD와 PAE는 PBG에 의하여 기존의 전력증폭기에 비하여 각각 $15\%$와 $25\%$ 개선되었다.

• Applied Science and Convergence Technology
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• 제26권3호
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• pp.43-46
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• 2017

Aluminum-doped ZnO (AZO) thin films were deposited by atomic layer deposition (ALD) with respect to the Al doping concentrations. In order to explain the chemical stability and electrical properties of the AZO thin films after hydrogen peroxide ($H_2O_2$) solution immersion treatment at room temperature, we investigated correlations between the electrical resistivity and the electronic structure, such as chemical bonding state, conduction band, band edge state below conduction band, and band alignment. Al-doped at ~ 10 at % showed not only a dramatic improvement of the electrical resistivity but also excellent chemical stability, both of which are strongly associated with changes of chemical bonding states and band edge states below the conduction band.

• Journal of Magnetics
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• 제11권3호
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• pp.139-142
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• 2006

We fabricated new one-dimensional magnetophotonic crystal (1D-MPC) utilizing the second and third photonic band gaps where localized modes existed. Structure of the 1D-MPC was $(Ta_{2}O_{5}/SiO_{2})_{5}/Bi:YIG/(SiO_{2}/Ta_{2}O_{5})_{5}$ with optical thicknesses of 3$\lambda$ /4 for $Ta_{2}O_{5} and $SiO_2$ dielectric layers and $\lambda$ /2 for Bi:YIG defect layer, where $\lambda$ is a wavelength of a localized mode in the second photonic band gap. Faraday rotation at the localized mode in the second photonic band gap was enhanced, which was confirmed by calculation using 4${\times}$4 matrix method.

• 대한전자공학회논문지TC
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• 제46권5호
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• pp.162-167
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• 2009

본 논문에서는 대역통과 여파기와 저역통과 여파기를 하나의 구조로 합성하여 크기 증가 없이 초광대역 특성을 가지는 여파기를 설계 및 구현하였다. 제안한 구조는 그 구조가 간단하다. 그리고 저역 통과 특성을 얻기 위하여 이미 잘 알려진 DGS(Defected Ground Structure) 구조를 이용하였다. 기존의 대역통과 여파기와 저역통과 여파기를 직접 연결하였을 때 보다 크기를 줄일 수 있었다. 측정결과 통과대역은 $2.1GHz{\sim}10.56GHz$이고 삽입손실은 최대 0.5dB, 반사손실은 최소 20dB, 군 지연은 $0.13ns{\sim}0.35ns$ 까지 최대 변화폭 0.23ns의 변화를 보인다.