• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1317-1324
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• 2011

We propose a method operated in a vehicle to measure light absorption of particles in atmosphere. The advantage of this method is that it is insensitive to light scattering and hence can be used for the direct measurement of the light absorption coefficient without suffering from light scattering. With this method atmospheric light absorption can be measured at a time constant of 10 s. Further, our method allows for the real-time measurement of light absorption near a highway. The light absorption coefficients were high near a race track, an airport and the main gate where vehicles emitted carbonaceous particles.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.2
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• pp.207-222
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• 2018

In this study, light absorption of carbonaceous species in $PM_{2.5}$ was investigated using a dual-spot 7-wavelength Aethalometer(model AE33) with 1-min time interval between January 01 and September 30, 2017 at an urban site of Gwangju. During the study period, two Asian dust (AD) events occurred in April (AD I) and May (AD II), respectively, during which light absorption in total suspended particles was observed. Black carbon (BC) was the dominant light absorbing aerosol component at all wavelengths over the study period. Light absorption coefficients by aerosol particles were found to have 2.7~3.3 times higher at 370 nm than at 880 nm. This would be attributed to light absorbing organic aerosols, which is called brown carbon (BrC), as well as BC as absorbing agents of aerosol particles. Monthly average absorption ${{\AA}}ngstr{\ddot{o}}m$ exponent ($AAE_{370-950nm}$) calculated over wavelength range of 370~950 nm ranged from 1.10 to 1.35, which was lower than the $AAE_{370-520nm}$ values ranging from 1.19~1.68 that was enhanced due to the presence of BrC. The estimated $AAE_{370-660nm}$ of BrC ranged from 2.2 to 7.5 with an average of 4.22, which was fairly consistent to the values reported by previous studies. The BrC absorption at 370 nm contributed 10.4~28.4% to the total aerosol absorption, with higher contribution in winter and spring and lower in summer. Average $PM_{10}$ and $PM_{2.5}$ concentrations were $108{\pm}36$ and $24{\pm}14{\mu}g/m^3$ during AD I, respectively, and $164{\pm}66$ and $43{\pm}26{\mu}g/m^3$ during AD II, respectively, implying the greater contribution of local pollution and/or regional pollution to $PM_{2.5}$ during the AD II. BC concentration and aerosol light absorption at 370 nm were relatively high in AD II, compared to those in AD I. Strong spectral dependence of aerosol light absorption was clearly found during the two AD events. $AAE_{370-660nm}$ of both light absorbing organic aerosols and dust particles during the AD I and II was $4.8{\pm}0.5$ and $6.2{\pm}0.7$, respectively. Higher AAE value during the AD II could be attributed to mixed enhanced urban pollution and dust aerosols. Absorption contribution by the light absorbing organic and dust aerosols estimated at 370 nm to the total light absorption was approximately 19% before and after the AD events, but it increased to 32.9~35.0% during the AD events. In conclusion, results from this study support enhancement of the aerosol light absorption due to Asian dust particles observed at the site.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.307-309
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• 2005

We investigated light absorption layer effect on metal-induced lateral crystallization (MILC) growth rate and MILC thin films transistors (TFTs). As annealing method, we used scanning-rapid thermal annealing (RTA). MILC growth rate which was crystallized by light absorption layer and using scanning-RTA was 3 times than normal MILC which was without light absorption layer growth rate. Also we compared MILC TFTs characteristics which were combined to light absorption layer with conventional MILC TFTs. After scanning-RTA process, MILC-TFTs which were with light absorption layer were superior to conventional MILC-TFTs. With this new MILC-TFTs structure, we could reduced crystallization time and obtain good electrical properties.

• Analytical Science and Technology
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• v.34 no.5
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• pp.225-230
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• 2021

Currently, most photoluminescence reagents used in forensic science have short stokes shift, making it difficult to observe strong photoluminescence due to scattering light from forensic light sources when using filters that are not shieldable. However interference filters can be observed near monochromatic light, making them a better alternative to absorption filters. To verify practical applicability of interference filters, interference filters and three other types of previously frequently used absorption filters were observed using a variety of light source products, and transmission light was cross-compared. Interference filters have a lower slope value than absorption filters, and selectively show only the photoluminescence of reagents, regardless of the type of product from the forensic light source. In addition, tilting the angle of the filter surface for observation lowered the λ_cut-on, which could replace various types of absorption filters with a single interference filter.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.9-14
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• 2014

We numerically investigate the effect of sunlight polarization on the absorption efficiency of V-shaped organic solar cells (VOSCs) using the finite element method (FEM). The spectral distribution of absorbance and the spatial distribution of power dissipation are calculated as a function of the folding angle for s-and p-polarized light. The absorption enhancement caused by the light-trapping effect was more pronounced for s-polarized light at folding angles smaller than $20^{\circ}$, where s-polarized light has a relatively larger reflectance than p-polarized light. On the other hand, the absorption efficiency for p-polarized light is relatively larger for folding angles larger than $20^{\circ}$, where the smaller reflectance at the interface of the VOSC is more important in obtaining high absorption efficiency.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.4
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• pp.411-422
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• 2012

Ground-based in-situ measurements of aerosol optical properties at Gosan climate observatory have been analyzed to investigate the optical contribution of Asian dust and polluted particles on light absorption in springtime 2011. During the Asian dust episode, the contribution of Asian dust particle to aerosol absorption coefficient estimated about 45% at 370 nm and about 23% at 520 nm. Especially, black carbon in dust plume contributes about 48% to aerosol light absorption at 520 nm since the airmass are transported from the Gobi and inner Mongolia deserts, and this airmass comes across the northeastern coast of China, near the Shandong Peninsula. In pollution case, the contributions of dust particle and black carbon to aerosol absorption coefficient estimated about 41% and 11% at 370 nm, respectively. However, pollution case shows the highest light absorption of 48% for brown carbon at 370 nm, which indicates the significantly high mass concentration of organic carbon ($6.3{\pm}2.2{\mu}g\;m^{-3}$) in pollution plume can contribute to the increase of light absorption at near-UV spectral region.

• Current Optics and Photonics
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• v.7 no.2
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• pp.136-146
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• 2023

Based on calculations using the macroscopic Maxwell's equations with mesoscopic boundary conditions, light absorption by a layered metal-insulator-metal (MIM) metamaterial system embedded in three different environments is investigated. Increasing the top metal thickness shifts the broad absorption band to lower dielectric-constant regions and longer wavelengths, for either TM or TE waves. Boosting the dielectric-layer thickness redshifts the broadband absorption to regions of larger dielectric constant. In air, for the dielectric-constant range of 0.86-3.40, the absorption of the system exceeds 98% across 680-1,033 nm. In seawater with optimized dielectric constant, ≥94% light absorption over 400-1,200 nm can be achieved; particularly in the wavelength range of 480-960 nm and dielectric-constant range of 0.82-3.50, the absorption is greater than 98%. In an environment with even higher refractive index (1.74), ≥98% light absorption over 400-1,200 nm can be achieved, giving better performance. The influence of angle of incidence on light absorption of the MIM system is also analyzed, and the angle tolerance for ≥90% broadband absorption of a TM wave is up to 40° in an environment with large refractive index. While the incident-angle dependence of the absorption of a TE wave is nearly the same for different circumstances, the situation is different for a TM wave.

• The Korean Journal of Ecology
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• v.8 no.2
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• pp.61-68
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• 1985

The modeling of interception and absorption of light was studied in plant canopies at Mt. Kwanak. Followering results were obtained. Light intensity passing through the stacked leaves is attenuated exponentially. This phenomenon seems to be more clearly applied to the plant canopies, if they have large cumulative leaf area and are matured densely. Light interception and absorption are influenced by leaf thickness, shape pigments, and leaf area, and they have great effect on the maturation of canopies. It was confirmed that the light penetrating through the stratified canopies is decreased exponentially in dual pattern. The cumulative leaf area of a definite space in a certain plant canopy is the same as the growth of leaf area of the canopy at that time. A hypothetical model for calculating the light absorption in plant canopies, was established on the bases of phenomena that incident light is captured at the maximum level and light inerception effect is minimized by leaves.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.830-839
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• 2008

This study is designed to manufacture the upgraded sound absorption concrete by using foamed concrete by using artificial light weight aggregate which raises the continuous void ratio to increase the sound absorption ratio and improve the strength. In manufacturing the sound absorption block, the pre-foaming form is applied to generate continuous voids, controlling the density by the addition of bubbles. It is general that the more porosity creates, the weaker strength becomes. Each of specimens are used for this experiment and measured their absorption ratio to examine the absorption property depending on frequency. As a results of experiment, it is evaluated that the absorption capacity of the sound absorption block has relation to compression strength and surface shape.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1723-1726
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• 2008

In recent years, there has been a remarkable progress in the development of the fiber optic sensors for the detection of various chemicals. Fiber optic sensors have the advantages of very small size, flexibility and low cost. The fiber optic sensors employing different optical or spectroscopic phenomena have been reported such as bulk absorption, optical reflectance, fluoresces and energy transfer. In this study, the effect of nanoparticle concentration in liquid upon light absorption and scattering was studied using extrinsic fiber optic method. For the evaluation, we used Red (650 nm) and Blue (430 nm) light sources which are coupled through the standard cuvette using optical fiber to detector. The experiments are carried out with Polystyrene latex (400 - 800 nm), and Silicon (35 - 110 nm) nanoparticles suspended in Isopropanol. Differences in light absorption and scattering depending on nanoparticle concentration and type are discussed. This method may be useful to study nanoparticles properties for various application and research.