• Title/Summary/Keyword: refractive index distribution

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Study on Characteristics of Change of Urea and Biuret Content by Temperature Variation in Urea Solution (요소수(Urea solution)의 온도변화에 따른 요소 및 뷰렛함량 변화 특성 연구)

  • Doe, Jin-woo;Park, Tae-sung;Lee, Yu-rim;Yim, Eui-soon;Lee, Joung-min;Kang, Hyung-kyu
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.4
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    • pp.1307-1319
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    • 2018
  • As interests in the air pollution increases, many kinds of researches are underway on the reduction of air pollutants. The removal of nitrogen oxides from the emission gas of diesel vehicles using urea solution has shown a great effect. The quality of urea solution is strictly defined by domestic law, but the increase of impurities in urea solution reduces the effect of reducing nitrogen oxides. Therefore, in this study, the change of physical properties of urea solution was analyzed after heating the urea solution for a certain temperature and time. Also, the changes of physical properties of urea solution were analyzed according to kinds of storage container and temperature for storing the urea solution. After heating the urea solution for a certain period of time, the biuret content in urea solution increased and the content of urea decreased. As the urea content decreased, both density and refractive index decreased. In the storage stability test carried out at a constant temperature with iron and PET containers, no change in physical properties was observed.

Changes of Body Balance on Static Posture According to Types of Induced Ametropia (정적자세에서 유도된 비정시의 유형에 따른 신체균형의 변화)

  • Kim, Sang-Yeob;Moon, Byeong-Yeon;Cho, Hyun Gug
    • Journal of Korean Ophthalmic Optics Society
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    • v.19 no.2
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    • pp.239-246
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    • 2014
  • Purpose: This study was performed to investigate the effect of induced ametropia on static posture for body balance. Methods: Twenty subjects (10 males, 10 females) of average age $23.4{pm}2.70$ years were participated and ametropia(binocular myopia; BM, simple myopic anisometropia; SMA, binocular hyperopia; BH, and simple hyperopic anisometropia; SHA) were induced with ${pm}0.50D$, ${\pm}1.00D$, ${\pm}1.50D$, ${\pm}2.00D$, ${\pm}3.00D$, ${\pm}4.00D$, ${\pm}5.00D$, respectively. General stability (ST), weight distribution index (WDI), and fall risk index (FI) were measured using TETRAX the biofeedback systems. Each index of the body balance was evaluated for 32 seconds in each ametropic condition and those value was compared with the value in fully corrected condition. Results: The ST showed significant increase from +0.50 D under condition of BM, from +1.00 D under condition of SMA, from -1.00 D under condition of BH, and from -1.50 D under condition of SHA compared with under condition of fully corrected condition, respectively. The FI showed significant increases from +4.00 D under condition of BM, from -1.00 D under condition of BH, and from -1.50 D under condition of SHA. The WDI show no change in all ametropia condition. Conclusions: Whatever ametropia is, uncorrected refractive error could reduce the general stability of body balance and increase the falling risk.

Preparation and Physical Properties of Hydrogle Lens Containing N,N-Dimethylacrylamide (N,N-Dimethylacrylamide를 포함한 하이드로젤 렌즈의 제조 및 물리적 특성)

  • Kim, Tae-Hun;Sung, A-Young
    • Journal of the Korean Chemical Society
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    • v.54 no.6
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    • pp.761-765
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    • 2010
  • Poly (N,N-dimethylacrylamide) is very useful in various fields due to its remarkable properties, such as water solubility and biocompatibility. This study used N,N-dimethylacrylamide with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (N-vinyl-2-pyrrolidone) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Measurement of the physical properties of the copolymerized polymer showed that the water content was 36 - 42%, refractive index was 1.433 - 1.426 and visible ray transmittance 90 - 91% while the oxygen permeability showed a distribution between 13.1 and $21.29{\times}10^{-11}(cm^2/sec)$ ($mlO_2/mL{\times}mmHg$). The measurement showed that the increased amount of oxygen permeability of the copolymer measured using the polarographic method range between 11.0% and 80.5%. Based on the results of this study, the produced copolymer is suitable for use as a material to high oxygen permeability hydrogel lenses.

Fluorescence-labelling for analysis of protein in starch using asymmetrical flow field-flow fractionation (AF4)

  • Yoo, Yeongsuk;Choi, Jaeyeong;Zielke, Claudia;Nilsson, Lars;Lee, Seungho
    • Analytical Science and Technology
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    • v.30 no.1
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    • pp.1-9
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    • 2017
  • Starch is a mixture of amylose (AMY) and amylopectin (AMP) which are different in physical properties such as molar mass (M), rms radius ($R_g$) and hydrodynamic diameter ($d_H$). The rheological and functional properties of starch are influenced by various factors including the molecular size, molar mass distribution (MD) and the concentration ratio of AMY and AMP. It is also important to analyze proteinaceous material in starch as they affect the flavor and texture of food to which starch is added. In this study, asymmetrical flow field-flow fractionation (AF4) was employed for separation and quantitation of AMY and AMP in starches (Amaranth, potato, taros and quinoa). AF4 was coupled with a multi-angle light scattering (MALS) and a refractive index (RI) detector for determination of the absolute M, MD and molecular structure. It was found that AMP has the M and $R_g$ ranging $3.7{\times}10^7{\sim}6.5{\times}10^8g/mol$ and 84 ~ 250 nm, respectively. Also the existence of branch was confirmed in higher M. In addition, proteinaceous material in starch was analyzed by AF4 coupled with a fluorescence detector (FS) after fluorescence-labeling. AF4-FS with fluorescence-labelling showed a potential for investigation on existence of proteinaceous material and the interaction between proteinaceous material and polysaccharide in starch.

Universality of the Quasi-linear Relation Between the Order Parameter and the Normalized Birefringence of Aligned Uniaxially Anisotropic Molecules (정렬된 단축이방성 분자들의 질서변수와 상대 복굴절간 준선형 관계식의 보편성)

  • Kim, Sang Youl
    • Korean Journal of Optics and Photonics
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    • v.28 no.1
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    • pp.33-38
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    • 2017
  • The universality of the quasi-linear relation between the order parameter S and the normalized birefringence ${\Delta}n_{rel}$, $S=(1+a){\Delta}n_{rel}-a{\Delta}n^2_{rel}$ is confirmed. It is verified that the refractive index of liquid crystals distributed with regular polyhedral symmetry is isotropic and it is given as $\frac{1}{n^2_{av}}=\frac{1}{3}\(\frac{1}{n^2_e}+\frac{2}{n^2_o}\){\cdot}S$ and ${\Delta}n_{rel}$ of angular weighted liquid crystals that are initially distributed with regular polyhedral symmetry, are numerically calculated. Also ${\Delta}n_{rel}$ and S of liquid crystals that are conically distributed, keeping the rotational symmetry about z-axis are calculated as the apex angle of the cone is varied. Based on these calculated results, it is confirmed that the quasi-linear relation between S and ${\Delta}n_{rel}$ is universal, independent of the details of the distribution function.

Rigorous Analysis for Optical Impacts of Tapered Sidewall Profile on Trapezoidal Diffraction Grating (사다리꼴 회절격자에서 테이퍼 측면의 광학적 효과에 대한 정확한 분석)

  • Ho, Kwang-Chun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.5
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    • pp.151-156
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    • 2020
  • To analyze the diffraction properties of optical signals and the significant impacts of tapered sidewall profile at periodic trapezoidal 2D diffraction gratings, Toeplitz dielectric tensor is first defined and formulated by 2D spatial Fourier expansions associated with trapezoidal profile. The characteristic modes in each layer is then based on eigenvalue problem, and the complete solution is found rigorously in terms of modal transmission-line theory (MTLT) to address the pertinent boundary-value problems. Based on those one, the numerical analysis is performed on how the tapered side profile of grating structures with trapezoidal refractive index distribution affects the design of a sub-wavelength grating reflector. The numerical results reveal that this tapered sidewall profile plays a critical role in determining the reflection bandwidth, the average reflectance, and the band edge.

Polymerization and Characterization of Ophthalmic Polymer Containing Glycerol dimethacrylate with High Wettability (Glycerol dimethacrylate를 포함한 고습윤성 안의료용 고분자의 중합 및 특성)

  • Cho, Seon-Ahr;Kim, Tae-Hun;Sung, A-Young
    • Journal of the Korean Chemical Society
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    • v.55 no.2
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    • pp.283-289
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    • 2011
  • This study used glycerol dimethacrylate with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), MA (methacrylic acid) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Measurement of the physical properties of the copolymerized polymer showed that the water content was 22~32%, refractive index was 1.442~1.463 and visible ray transmittance 90.0~90.5% while the contact angle showed a distribution between 56 and $65^{\circ}$. Also, the measurement showed that the decreased amount of contact angle of the copolymer measured using the sessile drop method ranged between $9.89^{\circ}$ and $18.99^{\circ}$ with increase of glycerol dimethacrylate. Based on the results of this study, the produced copolymer is suitable for use as a material to high wettability ophthalmic lenses.

A Novel Atomic Layer Deposited Al2O3 Film with Diluted NH4OH for High-Efficient c-Si Solar Cell

  • Oh, Sung-Kwen;Shin, Hong-Sik;Jeong, Kwang-Seok;Li, Meng;Lee, Horyeong;Han, Kyumin;Lee, Yongwoo;Lee, Ga-Won;Lee, Hi-Deok
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.1
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    • pp.40-47
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    • 2014
  • In this paper, $Al_2O_3$ film deposited by thermal atomic layer deposition (ALD) with diluted $NH_4OH$ instead of $H_2O$ was suggested for passivation layer and anti-reflection (AR) coating of the p-type crystalline Si (c-Si) solar cell application. It was confirmed that the deposition rate and refractive index of $Al_2O_3$ film was proportional to the $NH_4OH$ concentration. $Al_2O_3$ film deposited with 5 % $NH_4OH$ has the greatest negative fixed oxide charge density ($Q_f$), which can be explained by aluminum vacancies ($V_{Al}$) or oxygen interstitials ($O_i$) under O-rich condition. $Al_2O_3$ film deposited with $NH_4OH$ 5 % condition also shows lower interface trap density ($D_{it}$) distribution than those of other conditions. At $NH_4OH$ 5 % condition, moreover, $Al_2O_3$ film shows the highest excess carrier lifetime (${\tau}_{PCD}$) and the lowest surface recombination velocity ($S_{eff}$), which are linked with its passivation properties. The proposed $Al_2O_3$ film deposited with diluted $NH_4OH$ is very promising for passivation layer and AR coating of the p-type c-Si solar cell.

Simulation and Examination for Beam Profile of DFB Laser with an Anti-reflection Coated Mirror (무반사 면을 갖는 DFB 레이저의 빔 분포 시뮬레이션과 검정)

  • Kwon, Kee-Young;Ki, Jang-Geun
    • Journal of Software Assessment and Valuation
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    • v.16 no.1
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    • pp.55-63
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    • 2020
  • Lasers for optical broadband communication systems should have excellent frequency selectivity and modal stability. DFB lasers have low lasing frequency shift during high speed current modulation. In this paper, when a refractive index grating and a gain grating are simultaneously present in a DFB laser having a wavelength of 1.55 ㎛, the dielectric film is coated so that reflection does not occur on the right mirror surface, so that ρr=0. For the first mode, which requires a minimum gain at the threshold, the beam distribution of the oscillation mode in the longitudinal direction and the radiated power ratio Pl/Pr were analyzed and compared for the cases of the phase of ρl=π and π/2. If the phase of ρl=π, in order to obtain a low threshold current and high frequency stability, κL should be greater than 8. In the case of the phase of ρl=π/2, for low threshold current, κL is necessary to be 1.0, where the oscillation frequency coincides with the lattice frequency. DFB lasers with an anti-reflection coated mirror have excellent mode selectivity than 1.55um DFB lasers with two mirror facets

An Assessment of Utilization of the Pungchon Limestone in Paper Industry (풍촌층 석회석의 제지 산업에서의 응용성 평가)

  • Lee, Na-Kyong;Noh, Jin-Hwan
    • Journal of the Mineralogical Society of Korea
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    • v.20 no.4
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    • pp.339-349
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    • 2007
  • For various types of the Pungchon limestone, diverse mineral characters of the limestone including their size and morphology are investigated by using of ELS and SEM to examine the possibility of application as fillers to paper industry. Also, the measurement of zeta potential and the evaluation of coagulation properties in calcite suspension was made for fine powders of the limestone to examine the applicability and efficiency in wet-papermaking process. Fine powder of the Pungchon lime-stone, largely controlled by original mineral characters of ore in mineralogical aspects, exhibits some-what different trend in particle morphology according to ore types, and thereby, the size distribution, zeta potential and coagulation properties also become different. The examined whiteness, brightness, opacity and sheet strength in hand sheet also show remarkable differences according to ore types. These are seemed to be basically due to the results of combined effects of whiteness, site distribution, refractive index, and morphology of the limestone powder on the properties of hand sheet. Considering the investigated results, all types of the Pungchon limestone appear to be sufficiently applicable to paper industry. Especially, the mega-crystalline calcite type is evaluated to be overall suitable for the purpose of paper industry due to the higher values in whiteness and brightness. In addition the fine powder of micro-crystalline calcite type is assessed particularly to have a good quality in sheet strength by virtue of irregular particle shape.