• 한국전자통신학회논문지
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• 제13권6호
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• pp.1213-1222
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• 2018

본 연구에서는 무질서 효과가 고려된, 새로이 가정한 가상 결정 근사법을 갖는 empirical pseudopotential method를 사용하여 온도와 조성비 변화에 따른 3원계 질화물계 화합물 반도체 $GaAs_{1-X}N_X$의 휨 매개변수 및 에너지 밴드갭을 계산하였다. 300K의 조성비 구간($0{\leq}x{\leq}0.05$)에서 에너지 밴드갭들이 급격히 감소하며, 해당하는 계산된 휨 매개변수가 15eV임을 알 수 있었다. 에너지 밴드갭 계산 결과로부터 굴절률 n과 고주파 유전상수 ${\varepsilon}$ 등의 광학상수를 계산하였고, 에너지 밴드갭 계산 결과는 실험치를 대체로 잘 설명하였다.

• 전기학회논문지P
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• 제65권1호
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• pp.72-75
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• 2016

In this paper, we proposes a internal antenna for wireless DVI dongle device using the folded monopole structure. The proposed antenna uses a basic structure of spiral and monopole. The antenna optimized for parameters length, gap, width, and rectangle of folded monopole antenna using the spiral structure. To confirm the characteristics of the antenna parameters, HFSS from ANSYS Inc. was used for the analysis. We used an FR4 dielectric substrate with a dielectric constant of 4.4. The DVI dongle size of the proposed antenna is $50{\times}40{\times}1.6mm$, and the size of the antenna area is $10{\times}40mm$. There is a value of return loss less then -10dB in 2.4GHz and 5.8GHz, band and the maximum antenna gain is -4.13dBi. The utilization possibility of the wireless DVI Dongle antenna have a folded monopole with spiral shape could be confirmed according to compare and analyze the simulation and measurement data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.366.1-366.1
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• 2014

The rare-earth oxides M2O3 (M=La, Pr, Gd) are good insulators due to their large band gap (3.9eV for Pr2O3, 5.6eV for Gd2O3), they have high dielectric constants (Gd2O3 K=16, La2O3 K=27, Pr2O3 K=26-30) and, compared to ZrO2 and HfO2, they have higher thermodynamic stability on silicon making them very attractive materials for high-K dielectric applications. Another attractive feature of some rare-earth oxides is their relatively close lattice match to that of silicon, offering the possibility of epitaxial growth and eliminating problems related to grain boundaries in polycrystalline films. Metal-organic chemical vapor deposition (MOCVD) has been preferred to PVD methods because of the possibility of large area deposition, good composition control and excellent conformal step coverage. Herein we report on the synthesis of rare-earth oxide complexes with designed alkoxide and aminoalkoxide ligand. These novel complexes have been characterized by means of FT-IR, elemental analysis, and thermogravimetric analysis (TGA).

• Journal of information and communication convergence engineering
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• 제2권2호
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• pp.93-96
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• 2004

The a-Si:H TFT using ferroelectric of $SrTiO_3$ as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to $SiO_2$ and $Si_{3}N_{4}$. Ferroelectric increases on-current, decreases threshold voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, retractive index of 1.8∼2.0 and resistivity of $10^{13}$~$10^{15}$ $\Omega$cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60∼100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8∼20 $\mu\textrm{m}$ and channel width of 80∼200 $\mu\textrm{m}$. And it shows that drain current is 3.4$\mu\textrm{A}$ at 20 gate voltage, $I_{on}$/$I_{off}$ is a ratio of $10^5$~$10^8$ and $V_{th}$ is 4∼5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5 $\mu\textrm{A}$ at 20 gate voltage and $V_{th}$ is 5∼6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.

• 한국전자파학회논문지
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• 제16권11호
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• pp.1067-1074
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• 2005

원형 마이크로스트립 안테나를 기본 구조로 하고 단점인 표면파의 영향을 개선하기 위해 접지면에 광 밴드 갭 구조를 취하여 대역폭을 늘리고 안테나의 후방 방사를 줄였다. 또한 광 밴드 갭의 형태를 각기 달리하여 그에 따른 안테나 특성의 변화를 관찰하였다. 끝으로 유전체 사이에 비유전율이 유전체보다 낮은 공기층을 삽입하여 전체적인 비유전율을 낮게 만들어 작은 크기로 높은 응답 주파수 특성을 보였다.

• Journal of Magnetics
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• 제11권4호
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• pp.195-207
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• 2006

The recently published and new results on design and fabrication of magnetophotonic crystals of different dimensionality are surveyed. Coupling of polarized light to 3D photonic crystals based on synthetic opals was studied in the case of low dielectric contrast. Transmissivity of opals was demonstrated to strongly depend on the propagation direction of light and its polarization. It was shown that in a vicinity of the frequency of a single Bragg resonance in a 3D photonic crystal the incident linearly polarized light excites inside the crystal the TE- and TM-eigen modes which passing through the crystal is influenced by Brags diffraction of electromagnetic field from different (hkl) sets of crystallographic planes. We also measured the faraday effect of opals immersed in a magneto-optically active liquid. It was shown that the behavior of the faraday rotation spectrum of the system of the opal sample and magneto-optically active liquid directly interrelates with transmittance anisotropy of the opal sample. The photonic band structure, transmittance and Faraday rotation of the light in three-dimensional magnetophotonic crystals of simple cubic and face centered cubic lattices formed from magneto-optically active spheres where studied by the layer Korringa-Kohn-Rostoker method. We found that a photonic band structure is most significantly altered by the magneto-optical activity of spheres for the high-symmetry directions where the degeneracies between TE and TM polarized modes for the corresponding non-magnetic photonic crystals exist. The significant enhancement of the Faraday rotation appears for these directions in the proximity of the band edges, because of the slowing down of the light. New approaches for one-dimensional magnetophotonic crystals fabrication optimized for the magneto-optical Faraday effect enhancement are proposed and realized. One-dimensional magnetophotonic crystals utilizing the second and the third photonic band gaps optimized for the Faraday effect enhancement have been successfully fabricated. Additionally, magnetophotonic crystals consist of a stack of ferrimagnetic Bi-substituted yttrium-iron garnet layers alternated with dielectric silicon oxide layers of the same optical thickness. High refractive index difference provides the strong spatial localization of the electromagnetic field with the wavelength corresponding to the long-wavelength edge of the photonic band gap.

• 한국진공학회지
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• 제12권S1호
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• pp.15-16
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• 2003

3-D photonic band-gap structures are fabricated from dielectric colloidal polystyrene beads through a centrifuge method. The fabricated photonic crystals exhibit opalescent colors under white light and show a clear diffraction peak dependent on the incident angle of the light beam. Also the scanning electron microscope image was taken to verify the face-centered cubic crystal structure. Bragg's law and Snell's law are employed to describe the position of angle resolved diffraction peaks. It was shown that the optically deduced effective refractive index and lattice constants were in good agreement with the crystal structure identified by scanning electron microscope.

• 한국전자파학회논문지
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• 제10권5호
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• pp.688-693
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• 1999

본 논문에서는 공기 절연 적층형 마이크로스트립 구조의 새로운 MMIC 3dB 커플러를 제안하였다. 제안된 커플러의 제작은 아주 간단하며, 유전체 공정을 필요로 하지 않는다. 제안된 커플러의 구조 해석을 위해서 HP-Momentum을 이용하였으며, 이를 통해 제안된 커플러의 구조를 최적화 하였다. 제작된 커플러는 22 GHz대역폭(23~GHz~45GHz)을 갖고 있었다. 또한, 제안된 커플러를 이용하여 Ka-Band용 평형 2단 증폭기를 성공적으로 제작하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.227-229
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• 2002

본 논문에서는 마이크로스트립 라인 전압제어 가변 대역통과필터를 제안한다. 박막 강유전체의 상대 유전율은 인가 전압에 따라 변하는 특성을 이용하였고, Au/BSTO/MgO/Au 구조로 설계하였다. 커플링 수가 3개인 공진기를 연결하여 공진기 사이의 간격을 잘 조절한 격과, 중심 주파수 16 GHz 에서 1.9 GHz의 튜닝 범위, 800MHz 내의 좁은 대역폭, 3dB 이내의 작은 삽입손실을 갖는 필터를 설계할 수 있었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.374-375
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• 2006

Three-dimensional artificial crystals with periodicity corresponding to terahertz wave lengths were fabricated by self-assembling monosized metal spherical particles. The metal crystals were weakly sintered to utilize them as templates. The metal templates were inverted to air spheres crystal embedded in dielectric resin though infiltration and etching. The resulting resin inverted crystals clearly presented the photonic stop gaps within terahertz wave region and the frequencies of the gaps were confirmed to agree well with calculation by plane wave expansion method.