• Title/Summary/Keyword: 수분평형

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Absorption Characteristics of Persimmon Powder Depending on Temperature Changes and Drying Methods (건조방법과 온도변화에 따른 감 분말의 흡습특성)

  • 이원영;김종국
    • Journal of the East Asian Society of Dietary Life
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    • v.11 no.6
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    • pp.479-484
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    • 2001
  • The absorption characteristics of persimmon powder related to different drying methods and various storage temperatures was investigated. The physical properties of persimmon powder by different drying methods displayed the largest amount of porosity in the freeze-dried sample, and the smallest in hot air dried sample. Equilibrium moisture was reached in 6 days. Monolayer moisture contents were predicted to 0.09687~0.19712(freeze drying), 0.07820~0.18617(vacuum drying) and 0.07715~0.18056(hot air drying) g H2O/g solid respectively using the BET equation. BET equation for isothermal absorption curve showed over 0.95 R-square for all dried methods. Monolayer moisture contents were increased as storage temperature was incremented because water molecular movement was more active and there was a greater chance to clash with the absorption surface area.

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The Influence of the Hygroscopic Components in the Cigarettes on the Sorption of Moisture (제조(製造)담배중 흡습성분(吸濕成分)과 평형수분(平衡水分) 연구(硏究))

  • Chang, Ki Woon;Kim, Byeoung Ku
    • Korean Journal of Agricultural Science
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    • v.16 no.1
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    • pp.111-117
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    • 1989
  • Six cigarette brands produced in Korea and U.S.A. were studied to find the effects of relative humidity, moisture sorption time, temperature, and the amounts of water extracts and total sugar in the brands on the equilibrium moisture contents. The equilibrium contents were higher in the domestic brands than foreign ones and the sorption rates of moisture were faster in the domestic cigarettes. The Korean brands with high contents of water extracts and total sugar had higher equilibrium moisture contents in the range of RH 40-80% at $20^{\circ}C$ for 72hours. These are the reasons that Korean brands contain higher ratio of flue-cured tobacco and American brands are blended with higher ratio of Burley tobacco.

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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.

Analytical Method for Moisture Vaporization of Concrete under High Temperature (고온조건에서 콘크리트의 수분증발 해석기법)

  • Lee, Tae-Gyu
    • The Journal of the Korea Contents Association
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    • v.17 no.7
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    • pp.538-545
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    • 2017
  • Moisture evaporates, when concrete is exposed to fire, not only at concrete surface but also at inside the concrete to adjust the equilibrium and transfer properties of moisture. The equilibrium properties of moisture are described by means of water vapor sorption isotherms, which illustrate the hysteretical behavior of materials. In this paper, the prediction method of the moisture distribution inside the concrete members at fire is presented. Finite element method is employed to facilitate the moisture diffusion analysis for any position of member. And the moisture diffusivity model of high strength concrete by high temperature is proposed. To demonstrate the validity of this numerical procedure, the prediction by the proposed algorithm is compared with the test result of other researcher. The proposed algorithm shows a good agreement with the experimental results including the vaporization effect inside the concrete.

Prediction of Moisture Migration of Concrete Including Internal Vaporization in Fire (화재시 내부증발을 고려한 콘크리트의 수분이동)

  • Lee, Tae-Gyu
    • Fire Science and Engineering
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    • v.23 no.5
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    • pp.17-23
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    • 2009
  • Moisture evaporates, when concrete is exposed to fire, not only at concrete surface but also at inside the concrete to adjust the equilibrium and transfer properties of moisture. The equilibrium properties of moisture are described by means of water vapor sorption isotherms, which illustrate the hysteretical behavior of materials. In this paper, the prediction method of the moisture distribution inside the concrete members at fire is presented. Finite element method is employed to facilitate the moisture diffusion analysis for any position of member. And the moisture diffusivity model of high strength concrete by high temperature is proposed. To demonstrate the validity of this numerical procedure, the prediction by the proposed algorithm is compared with the test result of other researcher. The proposed algorithm shows a good agreement with the experimental results including the vaporization effect inside the concrete.

Absorption Characteristics of and a Prediction Model for Spray-Dried Protein-bound Polysaccharide Powders isolated from Agaricus blazei Murill (아가리쿠스버섯에서 분리한 단백다당류 분말의 흡습특성과 예측모델)

  • Hong, Joo-Heon;Youn, Kwang-Sup
    • Food Science and Preservation
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    • v.16 no.5
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    • pp.719-725
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    • 2009
  • We investigated the absorption characteristics of protein-bound polysaccharide powders of various molecular weights isolated from the mushroom Agaricus blazei Murill. The monolayer moisture content calculated using the GAB equation showed a higher level of significance than did the BET equation. The higher the water activity, the lower the isosteric heat of sorption. The fitness of the isotherm curve was shown to be in the order of the Khun, Oswin, Caurie and Henderson models. The prediction model equations for moisture content were established by use of ln(time), water activity, and temperature.

Sorption Characteristics of Red Pepper Powder with Relative Humidity and Temperature (저장상대습도 및 온도에 따른 분말고추의 흡습특성(吸濕特性))

  • Kim, Hyun-Ku;Park, Mu-Hyun;Min, Byong-Yong;Suh, Kee-Bong
    • Korean Journal of Food Science and Technology
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    • v.16 no.1
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    • pp.108-112
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    • 1984
  • The sorption characteristics of red pepper powder stored at various relative humidity and temperature were studied. At low relative humidity below RH 57%, the sorption equilibrium was easily attained, whereas at higher relative humidity above RH 75%, the powder was browned by higher equilibrium moisture content. The moisture content of monolayer value for the powder was ranging from 11.32% to 12.13% with temperature. First order regression equation of equilibrium moisture content for relative humidity was determined.

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Moisture Sorption Characteristics and a Prediction Model of Anchovy Powder with Particle Size (입자크기에 따른 분말멸치의 흡습특성 및 예측모델)

  • Youn, Kwang-Sup
    • Food Science and Preservation
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    • v.17 no.4
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    • pp.513-518
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    • 2010
  • This study was carried out to estimate the moisture sorption characteristics and prediction model of anchovy powders with different particle size as above 80 mesh, 80-60 mesh and 40-60 mesh. The equilibrium moisture content had higher values at lower storage temperatures, and higher water activity. The monolayer moisture content calculated using the GAB equation showed a higher level of significance than that of BET equation. The estimated monolayer moisture content was 0.024-0.052 g $H_2O/g$ dry solid. The absorption enthalpy was calculated with different particle size and various water activities. It showed that the absorption energy was decreased with increasing water activity but no difference was found on particle size increasement. The fitness of the isotherm curve was shown to be in the order of Khun, Halsey, Caurie and Oswin model. The prediction model equations for the moisture content were established by ln(time), water activity, and temperature, respectively. The model equation will be helpful for future work on drying and storage of anchovy powder.

Moisture Sorption Characteristics of Model Food Powders (모형 식품 분말의 흡습 특성)

  • Kim, Dong-Woo;Chang, Kyu-Seob;Kim, Suk-Shin;Lee, Un-Hyun
    • Korean Journal of Food Science and Technology
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    • v.28 no.6
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    • pp.1146-1150
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    • 1996
  • The purpose of this research was to provide fundamental data required for the process design of conveying, storage and processing of food powders. Potato starch, corn starch, wheat protein, soybean protein, and model food powders prepared by mixing potato starch and wheat protein were selected and their sorption characteristics such as equilibrium moisture content, monolayer moisture content, and sorption enthalpy were determined. Equilibrium moisture content and monolayer moisture content of high starch powders were higher than those of high protein powders, and the equilibrium moisture content decreased with temperature. The determination coefficients of the regression equations to predict the equilibrium moisture content of food powders were from 0.997 to 0.999. Sorption enthalpy experiments indicated that powder of high moisture content showed lower sorption than that of low· moisture content, and the high protein powder showed lower sorption than high starch powder.

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