• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1034-1037
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• 2003

In this work, Integral photography with variable focusing lens arrays is proposed. We fabricate two-dimensional liquid crystal lens arrays using cohesion of UV curable polymer and lithography. Applied voltage to the cell alters the effective refractive index of the liquid crystal layer and results in a change of the focal length. By adjusting the focal length, synchronized elemental image array for real or virtual mode is integrated in front of or behind the lens array.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.189-191
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• 2013

This letter presents a compact metamaterial-based tunable zeroth-order resonant antenna. It is based on the double-negative unit cell with a function of tunable inductance realized by a varactor and impedance convertor in the shunt branch. The resonant frequency of the designed antenna ranges from 2.31 to 3.08 GHz, depending on the capacitance of the used varactor. Its size is very compact ($0.05{\lambda}_0{\times}0.2{\lambda}_0$) with a relatively wide tunable range of 29.1%. The impedance bandwidth of the antenna is from 20 to 50 MHz for the resonant center frequency. The measured maximum total realized gain is from -0.68 dBi (2.43 GHz) to 1.69 dBi (2.97 GHz). The EM-simulated and measured results are in good agreement.

• Analytical Science and Technology
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• v.8 no.4
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• pp.457-460
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• 1995

A new hollow fiber filled with the lower refractive index liquid as core constructs a liquid core optical fiber(LCOF). The LCOF have been used as colorimetric cell to determine elements Cr and Cu in the presence of 70%- 50% ethanol or 50% dioxane aqueous solution, based on colored complex of Chromium(VI) with Diphenycarbazid(DPC) and copper with Chromaurd S(CAS) respectively. The sensitivity (1/ng/ml) of calibration curve of Cr and Cu are 0.052, 0.017 over the range 0 - 25, 0 - 24(ng/ml) respectively. The Cr in the animal gum and Nation Standard of China are determined with recoveries of 94 - 102%.

• Solar Energy
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• v.6 no.1
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• pp.12-23
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• 1986

The PECVD $SiN_x:H$ films were made from the $SiH_4-N_2$ gas mixtures under such deposition conditions as 0.01 to 1.0 of $SiH_4/N_2$ volume ratio, 0.1 to $0.8W/cm^2$ of RF power, and 100 to $400^{\circ}C$ of substrate temperature. The deposition rate, refractive index, hydrogen concentration, N/Si composition, optical gap and electric conductivity were measured, and the thermal stability and the optimum deposition conditions were investigated for the application of these films to the solar cell materials.

• ETRI Journal
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• v.41 no.1
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• pp.61-72
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• 2019

In this paper, we demonstrate the current concepts in holographic tomography (HT) realized within limited angular range with illumination scanning. The presented solutions are based on the work performed at Warsaw University of Technology in Poland and put in context with the state of the art in HT. Along with the theoretical framework for HT, the optimum reconstruction process and data visualization are described in detail. The paper is concluded with the description of hardware configuration and the visualization of tomographic reconstruction, which is calculated using a provided processing path.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.167-172
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• 2021

he progressively improved sensing sensitivity (∆λ_SPR/∆n, nm/RIU) to detect the refractive index is observed on the SPR platform of an Au-covered epoxy gratings in an increase in potential cycling in a typical three-electrode cell. Here, a DVD-R optical disc was used as a structure template to prepare an Au-covered epoxy gratings, and the newly formed reverse track pitch structure on the epoxy substrate was used as a working electrode directly in aqueous sulfuric acid solution. It is expected that Au reconstruction by potential cycling in sulfuric acid electrolyte increases the packing density of Au atoms in the grain boundary and improves the propagation of electromagnetic waves.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1705-1707
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• 1997

In this work, a possible new PD de technique, based on the electro-optic effect(P effect), has been proposed. The refractive index ellipsoid of EO crystal, as $LiNbO_3$, is changed by both the externally a electric field and its hysteresis loop of which effect on this hysteresis loop gives rise t discrepancy of index variation. Therefore, an eq regarding the phase variation of modulated beam through $LiNbO_3$ crystal under applied e field, is newly proposed considering the influen hysteresis characteristics. For this purpose generated from needle-plane electrode in oil has detected by use of $LiNbO_3$ cell and analyzed b equation. As a result, it is observed that PD measu phase intervals are limited by the cr characteristics such as asymmertrical P-E hyst and half-wave voltage.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.334.2-334.2
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• 2016

Silicon nitride (SiNx:H) films are generally used as passivation layer on solar cell and they are usually made by plasma enhanced chemical vapor deposition (PECVD). In this study, we investigated the properties of silicon nitride (SiNx:H) films made by PECVD. Effects of mixture ratio of process gases with silane (SiH4) and ammonia (NH3) on the passivation qualities of silicon nitride film are evaluated. Passivation properties of SiNx:H are focused by making antireflection properties identical with thickness and refractive index controlled. The absorption coefficient of each film was evaluated by spectrometric ellipsometery and the minority carrier lifetimes were evaluated by quasi-steady-state photo-conductance (QSSPC) measurement. The optical properties were obtained by UV-visible spectrophotometer. The interface properties were measured by capacitance-voltage (C-V) measurement and the film components were identified by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectroscopy detection (RBS) - elastic recoil detection (ERD).

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.168.2-168.2
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• 2014

반사방지막 코팅(Anti-reflection coating)은 태양전지(Solar cell), 발광다이오드(LED) 등의 반사율을 낮추어 효율을 증대시키기 위하여 사용되고 있다. 본 실험에서는 유리 기판 위에 실리콘 타겟을 이용한 반응성 high power impulse magnetron sputtering (HIPIMS) 장비를 활용하여, 높은 공정 압력(High-pressure)에서 펄스폭(Pulse width)을 조절하여 $SiO_2$ 반사방지막 코팅층을 형성하였다. 또한, 기공이 더 많은 박막을 제작하기 위해 빗각증착(Oblique-angle deposition)을 적용하여 더 좋은 광학 특성을 갖는 반사방지막 코팅층을 형성하였다. UV-Vis spectrometer를 이용하여, 380~800 nm 파장에서 투과율(Transmittance)을 측정하여 비교, 분석하였다. Ellipsometer를 이용하여 $SiO_2$ 박막층의 굴절률(Refractive index)을 측정한 결과, 반사방지막 코팅층 내부 기공에 따라 다양한 굴절률을 가지는 것을 확인할 수 있었다. 또한, 코팅층 내부 기공의 형상을 확인하기 위해 SEM(Secondary electron microscopy)을 활용하여 코팅층 단면(Cross section)을 측정하였다. 이를 활용하여 낮은 굴절률을 갖는 반사방지용 $SiO_2$ 코팅층을 형성하여 태양전지의 광 변환 효율을 상승 시킬 수 있고, 발광다이오드의 광 추출 효율을 증가시킬 있을 것으로 여겨진다.

• Korean Journal of Materials Research
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• v.30 no.3
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• pp.131-135
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• 2020

Silver nanowire (AgNW) networks have been adopted as a front electrode in Cu(In,Ga)Se2 (CIGS) thin film solar cells due to their low cost and compatibility with the solution process. When an AgNW network is applied to a CIGS thin film solar cell, reflection loss can increase because the CdS layer, with a relatively high refractive index (n ~ 2.5 at 550 nm), is exposed to air. To resolve the issue, we apply solution-processed ZnO nanorods to the AgNW network as an anti-reflective coating. To obtain high performance of the optical and electrical properties of the ZnO nanorod and AgNW network composite, we optimize the process parameters - the spin coating of AgNWs and the concentration of zinc nitrate and hexamethylene tetramine (HMT - to fabricate ZnO nanorods. We verify that 10 mM of zinc nitrate and HMT show the lowest reflectance and 10% cell efficiency increase when applied to CIGS thin film solar cells.