• Nano
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• 제13권10호
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• pp.1850121.1-1850121.11
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• 2018

In this study, a series of $LaMnO_3$-diamond composites with varied $LaMnO_3$ mass contents supported on micro-diamond have been synthesized using a sol-gel method. The as-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and the Fourier transform infrared spectra (FTIR). Meanwhile, the photocatalytic performances were also tested by photoluminescence (PL) spectroscopy, ultraviolet-visible diffuse reflection spectra (UV-Vis DRS) and the degradation of weak acid red C-3GN (RC-3GN). Results show that the peak position of $LaMnO_3$ is shifted to low angle after the introduction of diamond, and perovskite particles uniformly distributed on the surface of diamond, forming a network structure, which can increase the active sites and the absorption of dye molecules. When the mass ratio of $LaMnO_3$ and diamond is 1:2 (LMO-Dia-2), the composite shows the most excellent photocatalytic activity. This result offers a sample route to enlarge the range of the application of micro-diamond and provide a new carrier for perovskite photocatalysts.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.566-574
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• 2015

We report for the first time highly efficient trans-reflective color filters capable of demonstrating coloration in both transmission and reflection modes by taking advantage of a multilayer stack consisting of MgF₂ and TiO₂ used respectively as the low and high index materials. In order to enable such trans-reflective performance, securing an optimal stop band assuming an appropriate bandwidth within the visible regime is pivotal, which was realized by tailoring the thicknesses and the numbers of TiO₂-MgF₂ bi-layers. Three devices were designed through rigorous simulations and developed via e-beam evaporation to demonstrate vivid blue, green, and red colors in the reflection mode, and yellow, magenta, and cyan colors in the transmission mode, featuring an enhanced efficiency exceeding 90% under normal incidence. The color performance of the filters was examined by referring to the chromaticity coordinates of the transmission and reflection spectra, alongside photographed color images. The dependence of the performance on the angle of incidence was explored with respect to incident polarization, indicating that a transmission surpassing 60% could be stably maintained up to an angle of 75°. Polarization independent transfer characteristics were especially achieved for the normal incidence. The proposed devices may be readily extended to other spectral regimes by adjusting the thicknesses of the films.

• 한국자기학회지
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• 제18권3호
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• pp.115-119
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• 2008

Permalloy를 30시간 볼밀 한 후 주사전자현미경으로 형상 및 입경을 분석하였으며, 볼밀 가공한 Permalloy의 입자들이 편편한 상을 가짐을 확인하였다. Permalloy를 실리콘 고무와 혼합하여 박형 전파흡수체를 제조하고 Network Analyzer을 이용하여 permalloy-고무 전파흡수체의 재료정수 및 전파흡수특성을 측정하였으며, 그들의 상관 관계를 비교 조사하였다. 가공한 permalloy-고무 복합재료는 높은 복소유전율 및 복소투자율을 가지며 미가공한 permalloy-고무 복합재료 보다 전파흡수 특성이 우수하였다. 또한 전파흡수체 두께에 따라서 정합주파수가 낮은 주파수 대역으로 shift 됨을 알 수 있고, 1.3 mm의 두께로 제조한 전파흡수체에서는 이동통신주파수 대역인 $1.65\;GHz{\sim}1.86\;GHz$에서 가장 우수한 전파흡수특성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1074-1078
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• 2004

열 중착 방법을 이용하여 copper(II)-phthalocyanine(CuPc) 박막을 glass 기판 위에 제작하였다. 박막은 열처리를 하지 않은 경우와 열처리 조건을 $150^{\circ}C$ 로 후열(annealing) 처리 하는 방식으로 하였으며 후열 처리한 경우 $150^{\circ}C$에서의 열처리 지속 시간을 각각 2시간, 3시간, 4시간으로 달리하였다. 제작된 박막의 전기전도도를 평가하기 위해 마이크로파의 근접장 효과를 이용한 근접장 현미경(near-field scanning microwave microscope)을 이용하여 비파괴적인 방식으로 CuPc 박막의 반사계수(reflection coefficient)를 측정하였다. CuPc 박막의 전기전도도 특성을 UV 흡수도를 통한 HOMO(highest occupied molecular orbital), LUMO(lowest unoccupied molecular orbital) 준위의 밴드갭의 shift 현상과 관련지어 설명하였다. 박막 표면 특성은 SEM(scanning microscope microscopy)을 통해 관측하였다. 열처리 지속 시간에 따른 CuPc 박막의 전기전도도 특성은 2시간으로 지속한 경우의 박막의 경우 가장 좋았으며 그 보다 더 오랜 시간 동안 열처리를 지속한 경우에는 전기 전도 특성이 오히려 나빠짐을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.141-141
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• 2012

The electronic and optical properties of Indium Zinc Tin Oxide (IZTO) thin films using gas environment were investigated by X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). REELS spectra revealed that the band gaps of IZTO thin films are 3.26, 3.07, and 3.46 eV for water mixed with oxygen, argon mixed with oxygen, and air environments, respectively. The measured band gaps by REELS are consistent with the optical band gaps obtained by UV-Spectrometer. The optical properties represented by the dielectric function $\mathfrak{m}$, the refractive index n, the extinction coefficient k, and the transmission coefficient T of the IZTO thin films with different gas environments were determined from a quantitative analysis of REELS spectra. The calculated transmission from quantitative analysis of REELS spectra shows good agreement with transmission measured by UV-spectrometer. The transmission values of 89% and low electrical resistivity of $3.55{\times}10^{-3}{\Omega}{\cdot}cm$ have been achieved for argon mixed with oxygen which indicates that the gas enviroment plays an important role in improving the electronic and optical properties of films.

• Macromolecular Research
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• 제12권1호
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• pp.1-10
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• 2004

The structural changes occurring in the isothermal crystallization processes of polyethylene (PE), poly-oxymethylene (POM), and vinylidene fluoridetrifluoroethylene (VDFTrFE) copolymer have been reviewed on the basis of our recent experimental data collected by the time-resolved measurements of synchrotron-sourced wide-angle (WAXS) and small-angle X-ray scatterings (SAXS) and infrared spectra. The temperature jump from the melt to a crystallization temperature could be measured at a cooling rate of 600-1,000 $^{\circ}C$/min, during which we collected the WAXS, SAXS, and infrared spectral data successfully at time intervals of ca. 10 sec. In the case of PE, the infrared spectral data clarified the generation of chain segments of partially disordered trans conformations immediately after the jump. These segments then became transformed into more-regular all-trans-zigzag forms, followed by the formation of an orthorhombic crystal lattice. At this stage, the generation of a stacked lamella structure having an 800-${\AA}$-long period was detected in the SAXS data. This structure was found to transfer successively to a more densely packed lamella structure having a 400-${\AA}$-long period as a result of the secondary crystallization of the amorphous region in-between the original lamellae. As for POM, the formation process of a stacked lamella structure was essentially the same as that mentioned above for PE, as evidenced from the analysis of SAXS and WAXS data. The observation of morphology-sensitive infrared bands revealed the evolution of fully extended helical chains after the generation of lamella having folded chain structures. We speculate that these extended chains exist as taut tie chains passing continuously through the neighboring lamellae. In the isothermal crystallization of VDFTrFE copolymer from the melt, a paraelectric high-temperature phase was detected at first and then it transferred into the ferroelectric low-temperature phase at a later stage. By analyzing the reflection profile of the WAXS data, the structural ordering in the high-temperature phase and the ferroelectric phase transition to the low-temperature phase of the multi-domain structure were traced successfully.

• 한국세라믹학회지
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• 제39권12호
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• pp.1124-1127
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• 2002

In this paper, we studied the effects of the electron reflection on shadow mask on which the electron reflecting materials with $WO_3-ZnS:Cu.Al-PbO-SiO_2$ system were screen-printed and we evaluated the variation of the electron beam mislanding in CRT. As a result, the green emitted spectra on the electron reflecting layer are observed due to the transformation of the electron energy, when the electron impacted on shadow mask. The beam mislanding is reduced about 40% in comperision with that of CRT made by the conventional method.

• Journal of Information Display
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• 제1권1호
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• pp.48-51
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• 2000

In this work, we proposed a reflective antiferroelectric liquid crystal display (AFLCD) using a half-wave cell whose inplane tilt angle is $22.5^{\circ}$. To check the validity of our design, we fabricated a reflective half-wave AFLC cell of which inplane tilt angle is $24.9^{\circ}$, and measured VIS reflection spectra, contrast ratio and response time. In the results, the half-wave AFLC cell in the reflective configuration exhibits high brightness, high contrast ratio of 20:1, and fast response time of $700{\mu}s$.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.54-58
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• 2003

In this study, the solution of Gel'fand-Levitan-Marchenko integral equation in the inverse scattering problem is efficiently solved for arbitrarily specified spectra pattern which are reflected from the restricted potential. The procedure is based on the successive approach without iterations. This method lessens the truncation errors which plague conventional design schemes using specific windows for reflection coefficients. It is shown that the method is adequate for the synthesis of the continuously varying one-dimensional potential of the nonuniformly distributed dielectric constants.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.452-454
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• 2007

가시광을 사용하여 시중에 시판되는 고기 육질의 특성을 파악하기 위해 기초 실험을 수행 하였다. 고기 육질의 특성은 분광분석법을 이용하여 측정하였다. 측정결과 540-580nm 영역에서 myoglobin의 분포에 따라 흡광도의 변화가 발생하였으며, 이를 통해 고기 육질에서 살코기와 지방의 분포를 통해 간편하게 고기육질 특성의 파악이 가능할 것으로 예상된다.