• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.2
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• pp.87-96
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• 2004

Acoustic performances of the steel-wire fabrics manufactured from the crushed tires were experimentally investigated for various thicknesses and bulk densities. The well- known two-cavity method was used to measure the characteristic impedances, the propagation constants, and the absorption coefficients. The normal absorption coefficients measured by the two-cavity method agreed well with those measured by the two-microphone impedance tube method. The experimental results showed that the magnitude and frequency range of the absorption coefficient were controllable by changing the thickness and the bulk density of the steel-wire fabrics. Therefore, the steel-wire fabrics from the crushed tires can be successfully used as a good sound absorbing material.

• Bulletin of the Korean Chemical Society
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• v.6 no.4
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• pp.225-228
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• 1985

The absorptions of Fe(Ⅲ), Tb(Ⅲ), Tl(Ⅰ), Ce(Ⅲ), Th(Ⅳ), and $UO_2^{2+}$ ions into the Dowex 50W-X2, 100-200 mesh resin were investigated by spectrophotometry to understand the abnormal strong absorption behavior of cations to cation exchange resins in concentrated HClO4. The distribution coefficients increase in the order : Tl(Ⅰ) < Fe(Ⅲ) < Tb(Ⅲ)∼Ce(Ⅲ) < $UO_2^{2+}$< Th(Ⅳ) and the order is interpreted in terms of the ratio of charge-to-ionic radius. The mole ratios of increment of $ClO_4^-$ ion absorption to metal ion absorption showed the same order as the distribution coefficients, which indicates that the electrostatic association between $ClO_4^-$ ion and metal ion plays a major role in the strong absorption.

• Journal of the Korean Wood Science and Technology
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• v.29 no.1
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• pp.16-21
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• 2001

Improvement of sound absorption capability of wood and wood-based board by resonant absorption was attempted. Sound absorption coefficients of wood and wood-based board which contain normal, simple perforation and stair type perforation had been estimated by the tube method using standing wave ratio. Sound absorption coefficients of wood specimens of simply perforated and perforated with stair were higher than that of normal specimens. Especially, in case of stair type perforation, it was about 50 to 60% higher than that of normal specimen in the frequency of 3 to 4KHz. It was considered that the cavity which had been formed by perforation with stair type behaved as a single resonator. Wood-based board showed good sound absorption coefficients in the frequency from 125Hz to 2KHz and that of perforated board showed a little higher in the frequency from 300Hz to 500Hz than that of normal board. The computed data of resonant frequencies at several sizes of cavity showed good accordance with the estimated data of those.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1727-1734
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• 2013

Synthesis and characterization of some novel symmetric bis-azospiropyrans are reported in this study. These bis-azospiropyrans are bifunctional chromophores with two spiropyrans linked by a bis-azo extended aromatic system that produce more color strength (large molar absorption coefficient in mero forms) due to appending two azospiropyran chromophores on one molecule. Comparing to the molar absorption coefficients of the conventional spiropyran chromophores (${\varepsilon}=0.31{\times}10^4\;M^{-1}{\cdot}cm^{-1}$) and mono-azospiropyran chromophores ($1.35{\times}10^4\;M^{-1}{\cdot}cm^{-1}$), the novel synthesized photochromes showed astonishingly increased molar absorption coefficients ($2.3-3.8{\times}10^4\;M^{-1}{\cdot}cm^{-1}$) at the same conditions. Such high molar absorption coefficients confers high sensitivity to light and more color intensity of mero form, that leads to improvement of their light sensitivity and better discrimination of spiro (OFF) form from mero (ON) ones in molecular switches. The structures were deduced from their MS, FT-IR, and $^1H$-NMR spectroscopic data and CHN analysis. All the synthesized photochemically bifunctional compounds revealed fluorescent emission in their colorless form which was faded out after exposing to UV light. Fluorescence quantum yield values of the mero forms were 0.25-0.81 and two high fluorescence quantum yield values (0.60 and 0.81) were found in these series.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.499-505
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• 1997

A non-invasive technique to measure absorption and scattering coefficients was investigated The reflected backscattered light from the surface of phantom and biological tissue was obtained by using a time-correlated single photon counting system in pico-second time domain. The absorption and scattering coefficients were acquired by the time of peak and asymptotic behavior of the time-resolved reflectance curve and agreed well the ones that is obtained with deconvolution method It was found that the approximation method was good for biological medium to calculate optical properties due to its convenience and accuracy.

• International Journal of Air-Conditioning and Refrigeration
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• v.8 no.2
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• pp.51-59
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• 2000

The purpose of the present study is to investigate the absorbing characteristics in a vertical falling film type absorber using LiBr-H$H_2O$ solution as working fluids with the concentration of 60 wt%. The experimental apparatus consists of an absorber with the diameter of 17.2 mm and the length of 1150 mm, a generator, an evaporator (condenser), a weak solution tank and a sampling trap device and so on. The parameters were the solution temperatures of 45 and 50$^{\circ}$C, coolant temperatures of 30 and 35$^{\circ}$C, and the film Reynolds numbers from 50 to 150. The pressure drop in the absorber increased as the solution and coolant temperatures decreased. The pressure drop in the absorber increased up to the film Reynolds number of 90, however, decreased at the film Reynolds number above 90. The maximum absorption mass flux was observed at the film Reynolds number of 90. Absorption mass fluxes increased as the coolant temperature decreased. Accordingly, absorption mass fluxes and heat transfer coefficients under the subcooled condition increased more than those under the superheated condition. It is claimed that heat transfer coefficients are deeply affected by the solution temperature more than the coolant temperature within the experimental range.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.896-901
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• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several compartments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method for various combinations of perforated plates, airspaces or porous materials. Based on these results, a guidance for the design of multiple layer perforated plate systems combined with airspaces and porous absorbing materials is discussed in detail.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.62-65
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• 2003

In this study, to confirm corrosion of reinforced concrete affected by carbonation, chloride ion diffusion, absorption ratio, air permeability, measured carbonation velocity coefficient, chloride ion diffusion coefficient, absorption coefficient, air permeability coefficient. Corrosion velocity under environment of complex deterioration. And than compared corrosion velocity with these coefficients. As the results of this study, the correlation coefficient between chloride ion diffusion coefficients and absorption coefficient was revealed that it is very high. As well, an increase in carbonation, chloride ion diffusion also increases corrosion velocity. It showed that corrosion velocity was affected by the carbonation, chloride ion diffusion, absorption ratio, air permeability. Generally, data on the development of these coefficient made with none, organic B, organic A, inorganic B, and inorganic A is shown. It showed that coating of surface prevent steel bar from deteriorating.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.388.1-388
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• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several companments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method fur various combinations of perforated Plates, airspaces or porous materials. (omitted)

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.4
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• pp.593-602
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• 2004

This paper is a study on the model of simultaneous heat and mass transfer process in the absorption of refrigerant vapor into a lithium bromide solution of water-cooled vertical plate absorber. The model can predict temperature and concentration profiles as well as the effect of Reynolds number on them. Also. the variations of the absorption heat and mass fluxes. and the heat and mass transfer coefficients have been investigated. The numerical result shows that the interface temperature and concentration decrease as film Reynolds number does. The absorption heat and mass fluxes, and the heat and mass transfer coefficients get their maximum values adjacent to the inlet solution. Analyses on a constant wall temperature condition have been also carried out to exam the reliability of the present numerical method by comparing to previous investigations.