• Title/Summary/Keyword: Absorption model

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Kinetics of Water Vapor Absorption by Sodium Alginate-based Films

  • Seog, Eun-Ju;Zuo, Li;Lee, Jun-Ho;Rhim, Jong-Whan
    • Preventive Nutrition and Food Science
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    • v.13 no.1
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    • pp.28-32
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    • 2008
  • Water vapor sorption by sodium alginate-based films may result in swelling and conformational changes in the molecular structure and affecting the water vapor barrier properties. Sodium alginate film specimens were dried in a vacuum freeze dryer and their moisture content was determined by an air-oven method. The water vapor absorption was determined at two different levels of water activities (0.727 and 0.995) and at three temperatures (10, 20, and $30^{\circ}C$), and kinetics were analyzed using a simple empirical model. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs 1/t. It was found that water vapor absorption kinetics of sodium alginate films were accurately described by a simple empirical model. The rate of water vapor sorption increased with increase in temperature and it showed temperature dependency following the Arrhenius equation. The activation energies varied from 49.18$\sim$149.55 kJ/mol depending on the relative humidity.

Modeling of the Parathyroid Hormone Response after Calcium Intake in Healthy Subjects

  • Ahn, Jae Eun;Jeon, Sangil;Lee, Jongtae;Han, Seunghoon;Yim, Dong-Seok
    • The Korean Journal of Physiology and Pharmacology
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    • v.18 no.3
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    • pp.217-223
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    • 2014
  • Plasma ionized calcium ($Ca^{2+}$) concentrations are tightly regulated in the body and maintained within a narrow range; thus it is challenging to quantify calcium absorption under normal physiologic conditions. This study aimed to develop a mechanistic model for the parathyroid hormone (PTH) response after calcium intake and indirectly compare the difference in oral calcium absorption from PTH responses. PTH and $Ca^{2+}$ concentrations were collected from 24 subjects from a clinical trial performed to evaluate the safety and calcium absorption of Geumjin Thermal Water in comparison with calcium carbonate tablets in healthy subjects. Indirect response models (NONMEM Ver. 7.2.0) were fitted to observed $Ca^{2+}$ and PTH data, respectively, in a manner that absorbed but unobserved $Ca^{2+}$ inhibits the secretion of PTH. Without notable changes in $Ca^{2+}$ levels, PTH responses were modeled and used as a marker for the extent of calcium absorption.

On Design of Half-Wave Resonators for Acoustic Damping in a Model Combustion Chamber (모형 연소실내 음향 감쇠를 위한 반파장 공명기의 설계에 관한 연구)

  • Park, Ju-Hyun;Sohn, Chae-Hoon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.05a
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    • pp.18-21
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    • 2008
  • Acoustic design parameters of a half-wave resonator are studied experimentally for acoustic stability in a model combustor. According to standard acoustic-test procedures, acoustic-pressure signals are measured. Quantitative acoustic properties of damping factor and sound absorption coefficient are evaluated and thereby, the acoustic damping capacity of the resonator is characterized. The diameter and the number of a half-wave resonator, its distribution are selected as design parameters for optimal tuning of the resonator. Acoustic damping capacity increases as the resonators with diameter increases. The optimum number of resonators or the optimum open-area ratio decreases as boundary absorption decreases.

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The Effect of Gas Absorption Induced a Change of Glass Transition Temperature in Microcellular Foamed Plastics (초미세 발포 플라스틱의 유리전이온도를 변화시키는 가스 용해량의 영향)

  • Hwang, Yun-Dong;Cha, Seong-Un
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.5
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    • pp.816-822
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    • 2001
  • The thermoforming process is widely used in the plastics industry to produce articles for the packaging, automotive, domestic construction and leisure industries. The microcellular foaming process appeared at M.I.T. in 1980s to save a quantity of polymer materials and increase their mechanical properties. The glass transition temperature of polymer materials is one of many important process variables in appling the microcellular foaming process to the conventional thermoforming process. The goal of this research is to evaluate the relation between gas absorption and glass transition temperature in batch process using microcellular foaming process. The weight gain ratio of polymer materials has a conception of gas absorption. Polymers such as acrylonitrile-butadiene-styrene(ABS), polystyrene(PS) have been used in this experiment. According to conventional Chows model and Cha-Yoon model, it was estimated with real experimental result to predict a change of glass transition temperature as a function of the weight gain ratio of polymer materials in batch process to gain microcellular foamed plastic products.

Factors Determining Intention to Continue Using E-HRM

  • NOERMAN, Teuku;ERLANDO, Angga;RIYANTO, Feri Dwi
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.2
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    • pp.1079-1089
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    • 2021
  • The development of information technology has promoted organizational transformation through the utilization of an electronic information system. This research aimed to identify factors that influence continuous intention to use E-HRM. This empirical research applies the Technology Acceptance Model and Cognitive Model for identifying significantly impacted areas of continuous intention to use E-HRM in a highly dynamic environment. The data were collected using questionnaires delivered directly to respondents. The sample was 100 employees of ESQ Group selected through random sampling. The variables used were subjective norms (X1), perceived behavioral control (X2), perceived innovativeness (Y1), cognitive absorption (Y2), satisfaction (Y3), and continuous intention to use E-HRM (Y4). Statistical analysis using Structural Equation Modelling (SEM) with Smart PLS was applied. The results revealed that behavioral control (X2) did not influence the continuous intention to use E-HRM (Y4) and that cognitive absorption (Y2) and satisfaction (Y3) did not significantly influence continuous intention to use E-HRM (Y4). Subjective norms (X1) significantly influenced both perceived innovativeness (Y1) and continuous intention to use E-HRM (Y4), perceived behavioral control (X2) significantly influenced both perceived innovativeness (Y1) and cognitive absorption (Y2), and perceived innovativeness (Y1) significantly influenced both satisfaction (Y3) and continuous intention to use E-HRM (Y4).

Structure and Photoreaction of Photoactive Yellow Protein

  • Imamoto, Yasushi;Harigai, Miki;Shimizu, Nobutaka;Kamikubo, Hironari;Yamazaki, Yoichi;Kataoka, Mikio
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.126-129
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    • 2002
  • The chromophore/protein interactions in the photocycle intermediates of photoactive yel- low protein (PYP) were probed by site-directed mutagenesis. The absorption spectra of L- intermediates produced from E46Q, T50V, and R52Q mutants were calculated using the absorption spectra of dark states and difference absorption spectra between L-intermediates and dark states, and compared with that of PYP$\_$L/. The absorption spectrum of R52Q$\_$L/ agreed with that of PYP$\_$L/, but those of E46Q$\_$L/ and T50V$\_$L/ were red-shifted. The effect of these mutations on the absorption spectrum for L-intermediate was comparable to that for the dark state, suggesting that the interaction around the phe-nolic oxygen of the chromophore is conserved in PYP$\_$L/ unlike the crystal structure. On the other hand, we have reported that the absorption spectra of Y 42F$\_$M/, T50V $\_$M/, and R52Q$\_$M/ agreed with that of PYP$\_$M/, but that of E46Q$\_$M/ was red-shifted, suggesting that the hydrogen bond of the chromophore with Glu46 is conserved but that with Tyr42 is broken in PYP$\_$M/. These results suggest that the chromophore inter-acts with Glu46 throughout the photocycle, but never directly interacts with Arg52. This model con- flicts with some of the structural model of PYP intermediates proposed based on the high-resolution X -ray crystallography.

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Absorption Characteristics of Soybean curd Powder by Drying Methods (건조방법에 따른 건조분말두부의 흡습특성)

  • Kim Jin-Sung;Kim Jun-Han;Ha Young-Sun
    • Food Science and Preservation
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    • v.12 no.1
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    • pp.54-61
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    • 2005
  • The absorption characteristics and their physical properties of hot air, vacuum and freeze dried soybean curd powder were investigated. Absorption conditions were at 5, 15, and 25 t with $0.11\~0.93$ water activities. Equilibrium moisture content and the monolayer moisture content determined by prediction models showed highest value in the freeze dried soybean curd powder due to porous structure. Absorption energy decreased with increasing water activity was not affected by drying method. In the comparisons of the isothermal absorption models, Oswin model generally was the best fit model for isothermal adsorption of soybean curd powder.

Numerical Modeling of an Inductively Coupled Plasma Sputter Sublimation Deposition System

  • Joo, Junghoon
    • Applied Science and Convergence Technology
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    • v.23 no.4
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    • pp.179-186
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    • 2014
  • Fluid model based numerical simulation was carried out for an inductively coupled plasma assisted sputter deposition system. Power absorption, electron temperature and density distribution was modeled with drift diffusion approximation. Effect of an electrically conducting substrate was analyzed and showed confined plasma below the substrate. Part of the plasma was leaked around the substrate edge. Comparison between the quasi-neutrality based compact model and Poisson equation resolved model showed more broadened profile in inductively coupled plasma power absorption than quasi-neutrality case, but very similar Ar ion number density profile. Electric potential was calculated to be in the range of 50 V between a Cr rod source and a conductive substrate. A new model including Cr sputtering by Ar+was developed and used in simulating Cr deposition process. Cr was modeled to be ionized by direct electron impact and showed narrower distribution than Ar ions.

Radiative Transfer Model of Dust Attenuation Curves in Clumpy, Galactic Environments

  • Seon, Kwang-il;Draine, Bruce T.
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.2
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    • pp.40.2-40.2
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    • 2016
  • The attenuation of starlight by dust in galactic environments is investigated through models of radiative transfer in a spherical, clumpy interstellar medium (ISM). We show that the attenuation curves are primarily determined by the wavelength dependence of absorption rather than by the underlying extinction (absorption+scattering) curve; the observationally derived attenuation curves cannot constrain a unique extinction curve unless the absorption or scattering efficiency is specified. Attenuation curves consistent with the Calzetti curve are found by assuming the silicate-carbonaceous dust model for the Milky Way (MW), but with the $2175{\AA}$ bump suppressed or absent. The discrepancy between our results and previous work that claimed the Small Magellanic Cloud dust to be the origin of the Calzetti curve is ascribed to the difference in adopted albedos; we use the theoretically calculated albedos whereas the previous ones adopted empirically derived albedos from observations of reflection nebulae. It is found that the model attenuation curves calculated with the MW dust are well represented by a modified Calzetti curve with a varying slope and UV bump strength. The strong correlation between the slope and UV bump strength, as found in star-forming galaxies at 0.5 < z < 2.0, is well reproduced if the abundance of the UV bump carriers is assumed to be 30-40% of that of the MW-dust; radiative transfer effects lead to shallower attenuation curves with weaker UV bumps as the ISM is more clumpy and dustier. We also argue that some of local starburst galaxies have a UV bump in their attenuation curves, albeit very weak.

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A Study of Dynamic Simulation of a Hybrid Absorption Chiller Utilizing Solar Power (태양열을 이용한 일이중 겸용 흡수식 냉온수기 동적성능 모사연구)

  • Shin, Young-Gy;Seo, Jung-A;Woo, Sung-Min;Kim, Hyo-Sang
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.967-972
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    • 2009
  • A dynamic model has been developed to investigate the operability of a single and double-effect solar energy assisted parallel type absorption chiller. In the study, main components and fluid transport mechanism were modeled. And solar radiation and the solar collector also were also modeled along with its control design. The model was run for the single mode with solar energy supply only and the solar/gas driving double effect mode. From the simulation results, it was found that the present configuration of the chiller is not capable of regulating solution flow rates according to variable solar energy input. And the issues of the excessive circulation flowrate and the mismatch between available solar power and cooling load discourages the use of the single mode, but the dual use of gas and solar power is recommendable in view of controllability and enhanced COP.

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