• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.718-724
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• 2006

The heterogeneous association behaviour of various concentration binary mixtures of mono alkyl ethers of ethylene glycol with ethyl alcohol were investigated by dielectric measurement in benzene solutions over the entire concentration range at 25 ${^{\circ}C}$. The values of static dielectric constant $\epsilon_0$ of the mixtures were measured at 1 MHz using a four terminal dielectric liquid test fixture and precision LCR meter. The high frequency limiting dielectric constant $\epsilon_\infty$ values were determined by measurement of refractive index $n_D$ ($\epsilon_\infty\;=\;n_D\;^2$). The measured values of $\epsilon_0$ and $\epsilon_\infty$ were used to evaluate the values of excess dielectric constant $\epsilon^E$, effective Kirkwood correlation factor $g^{eff}$ and corrective correlation factor $g_f$ of the binary polar mixtures to obtain qualitative and quantitative information about the H-bond complex formation. The non-linear behaviour of the observed $\epsilon_0$ values of the polar molecules and their mixtures in benzene solvent confirms the variation in the associated structures with change in polar mixture constituents concentration and also by dilution in non-polar solvents. Appearance of the maximum in $\epsilon^E$ values at different concentration of the polar mixtures suggest the formation of stable adduct complex, which depends on the molecular size of the mono alkyl ethers of ethylene glycol. Further, the observed $\epsilon^E$ < 0 also confirms the heterogeneous H-bond complex formation reduces the effective number of dipoles in these polar binary mixtures. In benzene solutions these polar molecules shows the maximum reduce in effective number of dipoles at 50 percent dilutions. But ethyl alcohol rich binary polar mixtures in benzene solvent show the maximum reduce in effective number of dipoles in benzene rich solutions.

• Asian Journal of Atmospheric Environment
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• 제9권1호
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• pp.91-99
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• 2015

The Multi-wavelength Raman LIDAR (MRL) system was developed to enable a better understanding of the complex properties of aerosols in the atmosphere. In this study, the microphysical, optical, and radiative properties of mixed aerosols were retrieved using the discrete aerosol observation products from the MRL. The dust mixing ratio, which is the proportion of dust particles to the total mixed, was derived using the particle depolarization ratio. It was employed in the retrieval of backscattering and extinction coefficient profiles for dust and non-dust particles. The vertical profiles of aerosol optical properties were then used as input parameters in the inversion algorithm for the retrieval of microphysical parameters including the effective radius, refractive index, and the single scattering albedo (SSA). Those products were successfully applied to an analysis of radiative flux using a radiative transfer model. The relationship between the MRL derived extinction and aerosol radiative forcing (ARF) in short-wavelength was assessed over Gwangju, Korea. The results clearly demonstrate that the MRL-derived extinction profiles are a good surrogate for use in the estimation of optical, microphysical, and radiative properties of aerosols. It is considered that the analytical results shown in this study can be used to provide a better understanding of air quality and the variation of local radiative effects due to aerosols.

• 한국표면공학회지
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• 제29권6호
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• pp.788-796
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• 1996

$TiO_2$ films prepared by RF magnetron sputtering, electron beam evaporation, ion assisted deposition (IAD) and sol-gel method are prepared on c-Si substrate and vitreous silica substrate respectively. From the transmission spectra of $TiO_2$ films on vitreous silica substrate in the spectral region from 190 nm to 900 nm, k($\lambda$) of $TiO_2$ is obtained. Using k($\lambda$) in the interband transition region the coefficients of the quantum mechanical dispersion relation of an amorphous $TiO_2$ and hence n($\lambda$) including the optically opaque region of above fundamental transition energy are obtained. The spectroscopic ellipsometry spectra of $TiO_2$ films in the spectral region of 1.5-5.0eV are model analyzed to get the film packing density variation versus i) substrate material, ii) film thickness and iii) film growth technique. The complex refractive index change of these $TiO_2$ films versus water condensation is also studied. Film micro-structures by SE modelling results are compared with those by atomic force microscopy images and X-ray diffraction data.

• 설비공학논문집
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• 제11권6호
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• pp.749-757
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• 1999

Holographic interferornetric tomography can provide reconstruction of instantaneous three dimensional gross flow fields. The technique however confronts ill-posed reconstruction problems in practical applications. Experimental data are usually limited in projection and angular scanning when a field is captured instantaneously or under the obstruction of test models and test section enclosures. An algorithm, based on a series expansion method, has been developed to improve the reconstruction under the ill-posed conditions. A three-dimensional natural convection flow around two interacting isothermal cubes is experimentally investigated. The flow can provide a challenging reconstruction problem and lend itself to accurate numerical solution for comparison. The refractive index fields at two horizontal sections of the thermal plume with and without an opaque object are reconstructed at a limited view angle of 80" The experimental reconstructions are then compared with those from numerical calculation and thermocouple thermometry. It confirms that the technique is applicable to reconstruction of reasonably complex, three-dimensional flow fields.elds.

• 한국광학회지
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• 제14권3호
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• pp.272-278
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• 2003

분광타원법을 이용하여 PDP용 ITO박막의 광학상수 및 패턴을 분석하였다. ITO 박막의 광물성은 로렌쯔 진동자 모델을 사용하고 ITO의 패턴에 의한 효과는 전체빔이 ITO와 유리기층을 덮는 면적비 가중치를 가진 반사율 평균방법으로 반영시켰다. PDP 다층박막을 구성하고 있는 유리기층 위의 ITO박막 패턴이 타원데이터에 미치는 영향을 분석하여 ITO가 패턴에서 차지하는 면적비를 결정하였다. 측정된 분광타원데이터에 최적맞춤한 ITO의 상대면적값이 예측값과 보이는 차이를 검토함으로써 분광타원법을 사용한 ITO패턴분석의 한계와 이를 극복하는 방법을 제시하였다.

• 센서학회지
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• 제28권4호
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• pp.236-239
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• 2019

In this work, we performed an optical simulation study on the performance of a PMDPP3T:PCBM based on an organic photovoltaic (PV) device. The virtual PV device was developed in Lumerical, finite-difference time-domain (FDTD) solutions. Different layers of the PV cell have been defined through the incorporation of complex refractive index value of those layers' constituent materials. During the simulation study, the effect of the variation active layer thickness on an ideal short circuit current density ($J_{sc,ideal}$) of the PV cell has been, first, observed. Thereafter, we have investigated the impact of surface roughness of a transparent conducting oxide (TCO) electrode on $J_{sc,ideal}$ of the PV cells. From this simulation, it has been observed that the $J_{sc,ideal}$ value of the PV cell is strongly dependent on the thickness of its active layer and the photon absorption of the PV cell has gradually decreased with the increment of the TCO's surface roughness. As a result, the capability of the PV device has been reduced with the increment of the surface roughness of the TCO.

• 분석과학
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• 제17권2호
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• pp.173-179
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• 2004

Ethylene glycol의 polymerization-complex route를 통한 졸-겔 합성법으로 안정하고 균일한 barium titanate 분말 및 박막을 제조하였다. 출발 용액으로 킬레이팅 리간드인 acetylacetone을 barium과 titanium 용액에 치환시켜 합성한 복합 산화물 졸 용액을 사용했을 때 박막을 만들 수 있었다. 졸 용액의 입자 분포도는 안정한 gaussian 분포를 보였으며, $1100^{\circ}C$에서 열처리한 겔 분말의 입자 크기는 40~77 nm이었다. 열분석 및 FT-IR, $^{13}C$ CP/MAS NMR 스펙트라와 XRD 결과로부터 (Ba-Ti)-oxycarbonate 중간상을 거쳐 $BaTiO_3$ 분말이 형성됨을 알 수 있었다. Quartz에 스핀 코팅으로 제조한 박막은 치밀하고 균열 없는 미세 조직을 보였다. $1100^{\circ}C$에서 열처리한 박막 표면의 입자 크기는 220 nm였으며 치밀한 입자 성장을 관찰할 수 있었다.

• 대한원격탐사학회지
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• 제30권1호
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• pp.47-59
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• 2014

화산재입자의 굴절률과 산란 같은 고유 광학 특성으로 결정되는 분광학적 신호는 원격탐사 센서를 통하여 측정될 수 있지만, 화산 폭발 이후 생성된 화산재입자의 성분에 대한 굴절률에 관한 정보는 매우 제한적이었다. 따라서, 화산재입자의 원격탐사의 강건성을 개선하기 위하여 화산재입자와 복사전달 과정의 상호작용에 대한 정확한 이해가 필요하다. 본 연구에서는 화산재 주요 성분으로 알려진 화산성 안산암과 부석에 대한 입자 소산계수, 산란 위상함수, 비대칭 계수, 단산란 알베도 값을 정량화 하였다. 이러한 화산재입자의 고유 광학 특성값은 복사전달모델의 입력자료로 이용하여 다양한 에어러솔 광학두께(${\tau}$) 및 기하조건에서 원격탐사 센서(인공위성과 지상관측용)가 측정하는 이론적인 복사량과 화산재입자 특성의 관계를 분석하였다. 복사전달모델 분석결과, 대기권 최상층부에서 ${\tau}$ 에 대한 복사량의 변화율의 평균값은 안산암의 경우 부석보다 6배 정도 크게 나타났다. 지표에서 이러한 변화율은 ${\tau}$ <1인 경우 양의 상관관계를 보이지만, ${\tau}$ >1인 경우에는 음의 상관관계를 보였다. 그러나, 적외선 영역인 11 ${\mu}m$ 에서는 차이가 매우 적게 나타났으며, 여기서 발생하는 복사량의 오차범위는 광학두께가 증가할수록 커지는 양상을 보이며, 다항 회귀함수로 표현될 수 있다. 이러한 결과는 원격 탐사 관측자료를 이용한 화산재 관측에 있어서 화산재의 정량적 분석에 도움이 될 것이다.

• 한국진공학회지
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• 제17권1호
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• pp.46-50
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• 2008

Febry-Perot 프린지 패턴의 광 반사성을 가지고 있는 다공성 실리콘을 이용하여 암호화된 광학 이미지를 제작하였다. 암호화된 광학이미지 다공성 실리콘 샘플은 p-type 실리콘 웨이퍼 (boron-doped,<100> orientation, resistivity $0.8{\sim}1.2m{\Omega}-cm$)를 이용하여 빔 프로젝트의 광원과 전기화학적 식각을 통하여 만들어 졌다. 광학 이미지 다공성 실리콘 샘플은 전기화학적 식각과정에 빔 프로젝트의 광원에 의하여 톡특한 Febry-Perot 프린지 패턴을 나타낸다. 실리콘 웨이퍼의 광 반사성의 프린지 패턴을 퓨리에 변환을 통하여 유효광학두께를 측정하고 실리콘웨이퍼에 암호화 시킨 광학이미지를 제작하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.222-222
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• 2011

Titanium dioxide (TiO2) has a number of applications in optics and electronics due to its superior properties, such as physical and chemical stability, high refractive index, good transmission in vis and NIR regions, and high dielectric constant. Atomic layer deposition (ALD), also called atomic layer epitaxy, can be regarded as a special modification of the chemical vapor deposition method. ALD is a pulsed method in which the reactant vapors are alternately supplied onto the substrate. During each pulse, the precursors chemisorb or react with the surface groups. When the process conditions are suitably chosen, the film growth proceeds by alternate saturative surface reactions and is thus self-limiting. This makes it possible to cover even complex shaped objects with a uniform film. It is also possible to control the film thickness accurately simply by controlling the number of pulsing cycles repeated. We have investigated the ALD of TiO2 at 100$^{\circ}C$ using precursors titanium tetra-isopropoxide (TTIP) and H2O on -O, -OH terminated Si surface by in situ X-ray photoemission spectroscopy. ALD reactions with TTIP were performed on the H2O-dosed Si substrate at 100$^{\circ}C$, where one cycle was completed. The number of ALD cycles was increased by repeated deposition of H2O and TTIP at 100$^{\circ}C$. After precursor exposure, the samples were transferred under vacuum from the reaction chamber to the UHV chamber at room temperature for in situ XPS analysis. The XPS instrument included a hemispherical analyzer (ALPHA 110) and a monochromatic X-ray source generated by exciting Al K${\alpha}$ radiation (h${\nu}$=1486.6 eV).