• Journal of Biosystems Engineering
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• 제15권1호
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• pp.44-51
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• 1990

Four models in current use for cereal grain drying, equilibrium model, Morey model, partial differential equation model and simplified partial differential equation model, were modified to be suitable for natural air drying of barley. The predicted by the four models and experimental results were compared. Three models except equilibrium model predicted moisture comtent and grain temperature very well. But equilibrium model overpredicted moisture content and grain temperature of bottom layer. The degree of prediction of the four models for relative humidities of exhaust air didn't differ much from one another and equally the four models predicted relative humidity statisfatorily. Morey model took much shorter computing time than any other models. Therefore, considering the degree of prediction and computing time Morey model was the most suitable for natural air drying of barley.

• 한국식품과학회지
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• 제16권1호
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• pp.108-112
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• 1984

분말고추를 상대습도 11%에서 84%까지 8단계의 RH조건별로 $15^{\circ}C,{\;}25^{\circ}C$ 및 $35^{\circ}C$ 온도구에 저장하면서 분말고추의 흡온특성(吸溫特性)을 조사하였다. 저장시간에 따른 분말고추의 흡습곡선은 RH57% 이하에서는 단시간내에 평형에 도달하여 수분함량의 변화가 거의 없었으나 RH75% 이상에서는 평형수분함량이 급격히 증가하여 갈변현상이 발생하였다. 분말고추의 단분자층(單分子層)의 수분함량은 온도에 따라서 11.32%에서 12.13%로서 온도가 하강함에 따라 다소 증가하는 경향을 보였으며 상대습도에 따라서 평형수분함량을 예측할 수 있는 1차 회귀방정식을 도출하였다

• Preventive Nutrition and Food Science
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• 제20권3호
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• pp.215-220
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• 2015

The moisture sorption isotherms of vacuum-dried edible green alga (Capsosiphon fulvescens) powders were determined at 25, 35, and $45^{\circ}C$ and water activity ($a_w$) in the range of 0.11~0.94. An inversion effect of temperature was found at high water activity (>0.75). Various mathematical models were fitted to the experimental data, and Brunauer, Emmett, and Teller model was found to be the most suitable model describing the relationship between equilibrium moisture content and water activity (<0.45). Henderson model could also provide excellent agreement between the experimental and predicted values despite of the intersection point. Net isosteric heat of adsorption decreased from 15.77 to 9.08 kJ/mol with an increase in equilibrium moisture content from 0.055 to $0.090kg\;H_2O/kg$ solids. The isokinetic temperature ($T_{\beta}$) was 434.79 K, at which all the adsorption reactions took place at the same rate. The enthalpy-entropy compensation suggested that the mechanism of the adsorption process was shown to be enthalpy-driven.

• 농업과학연구
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• 제16권1호
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• pp.111-117
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• 1989

시판(市販)되고 있는 국산(國産)담배와 외산(外産)담배 각각(各各) 3종(種)을 대상(對相)으로 담배각초(刻草)의 평형수분(平衡水分), 전당(全糖) 및 수추출물(水抽出物)등을 분석(分析)하여 측정(測定)하여 얻은 결과(結果)를 요약(要約)하면 다음과 같다. 1. 담배의 평형수분(平衡水分)은 국산(國産)담배가 외산(外産)담배에 비하여 높다. RH80%에서 24시간(時間) 보존(保存) 후(後)에 함수분(含水分)은 SOL은 Y.S.L보다 3.3%, EUNHASU는 Marlboro(L) 보다 2.4%가 높았다. 2. 제조(製造)담배의 온습도별 함수분(含水分) 변화(變化)의 경우(境遇), 국내외산(國內外産) 제조(製造)담배의 흡습속도(吸濕速度)는 국산(國産)담배가 외산(外産)담배에 비(比)하여 빨랐다. 3. 담배 각초(刻草)의 수추출물(水抽出物)에 따른 상대습도별(相對濕度別) 평형수분(平衡水分)은 국산(國産)담배는 외산(外産)담배에 비(比)하여 높았다. 4. 담배 각초(刻草)의 전당함량(全糖含量)이 상대습도(相對濕度)에 따른 담배 평형수분(平衡水分)은 국산(國産)담배가 외산(外産)담배에 비(比)하여 높았다. 이와 같은 국산(國産)담배가 평형수분(平衡水分)이 높고, 흡습속도(吸濕速度)가 빠른 것은 국산(國産)담배가 황색종(黃色種)이 많이 배합(配合)되어 있는 반면(反面) 외산(外産)담배는 버어리엽(葉)이 다량배합(多量配合)되어 있는 결과(結果)라고 추정(推定)된다.

• 한국가구학회지
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• 제19권1호
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• pp.75-82
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• 2008

A series of the studies on the applied physical properties of main domestic species have been conducted last three years. Equilibrium moisture content(EMC) of Pinus koraiensis, Larix kaemferi, Pinus koraiensis were investigated. The experiments for sorption property were conducted with 20- and 80-mesh wood powder and resulted in their EMC's at various sorption conditions. Amount of moisture sorption and sorption speed of Larix kaemferi were shown the most large values and very fast among three Korean main coniferous wood.

• Journal of Ginseng Research
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• 제5권1호
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• pp.1-7
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• 1981

A study was designed to study the sorption characteristics of powder-type products of red ginseng such as red ginseng tea, red ginseng powder and spray 4ried powder of red ginseng extract The sorption rates and equilibrium moisture contents on these products were calculated at ova. a range of relative himidities and two different temperatures ($25^{\circ}C$ and 38$^{\circ}C$). Significant differences between these three products were found in water activities, sorption rates and the relationship between the ratio of %H2O/RH and moisture content The red ginseng tea required the most excessive drying to reach aw=0.4, followed by red ginseng power and spray dried powder of red ginseng extract Attempt was made to obtain equations which can predict sorption rate and moisture content of red ginseng products at given relative humidity and temperature after certain period of storage.

• 한국농공학회논문집
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• 제57권1호
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• pp.79-87
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• 2015

A thermochemical equilibrium model was constructed for predicting composition of synthesis gas in biomass gasification. The model included estimation of equilibrium constants using Gibbs free energy. After constructing the model, the results were compared with the experimental values and predictions from a previous model. Gas compositions were reasonably well agreed with them and showed effects of operational and fuel condition. When the reaction temperature increased, the lower heating values decreased due to the decrease in CH4 concentrations. The methane concentrations were lower than those observed in experimental results. The model was used to predict the gas composition and heating values for the cases of mixed fuel of charcoal and un-dry woodchips. Although downdraft gasifiers require fuels less than 15% of moisture contents, the model results indicated that the mixed fuel with charcoal and woodchips which had over 25% of moisture contents could be used in the downdraft gasifiers. It might be explained by increase in energy density resulting from mixing charcoal. The results imply that the efforts and costs for drying biomass fuels could be reduced by mixing charcoal or fuels with higher calorific values.

• 한국가구학회지
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• 제20권6호
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• pp.599-604
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• 2009

For the search of unified law of moisture movement in wood, moisture distribution of Korean red pine at non-steady state was investigated. We assume that the equilibrium moisture content (EMC) in wood depends on only temperature and relative humidity, it can be control in temperature and humidity chamber. If temperature is constant and humidity or vapor pressure is changed with sin curve shape at adequate cycles, EMC in chamber can be changed as well with sin-curve shape. The setup condition of a non-steady state in humidity control chambers is a constant temperature at $20^{\circ}C$ and 15+10 sin ${\omega}t$ percent EMC. It can be found that the distribution of moisture in the specimen with varying relative humidity are illustrated various types. Moisture in wood is complicated and vibrates with the moisture sorption process. Considering a unified law of moisture movement in wood, it is considered that the most important fact is to search the method of precise diffusion & transfer coefficients.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.28-36
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• 1997

Several thick board and dimension lumbers of Japanese larch(Larix leptolepis), Dahurian larch(Larix gmelini) and radiata pine(Pinus radiata) air-dried in four different seasons to compare air-drying process. Patterns of air-drying curves were influenced by climatological conditions and limber thickness. The initial drying rates of summer were the highest, followed those of fall, spring and winter. The drying times to equilibrium moisture contents for four seasons were nearly the same except for winter. However, the drying time for winter required twice more time than the other seasons. The drying time of dimension lumbers required 1.3 times more than boards. The final moisture contents were lowest during spring, highest during winter and similar between summer and fall.

• 한국연초학회지
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• 제15권1호
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• pp.90-97
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• 1993

1. Average moisture content of tobacco in BIB silo was about 19: 1% until 4hours conditioned time, and then moisture variation of tobacco after 2hr conditioned was very small. 2. Application of mathematical model for ordering system. 1) The constant K in the exponential equation varies inversely with both relative humidity and equilibrium moisture. 2) Time needed to order blending tobacco leaves with standard moisture from bulking and blending silo was 4 hours. 3) Reconstituted tobacco sheet had higher moisture absorption ratio than Oriental and Burley tobacco. 4) For minimize of conditioning time in BIB silo, the values of K and Mo given in this study can be used in equation(1) to calculate moisture absorption ratio and optimum conditioning time. 3. Average moisture content and water activity of conditioned tobacco for 4 hours in BIB silo was about 20% and 0.65. In this condition. microbial life will inhibite 4. Physical properties of conditioned tobacco in bulking and blending silo for 4hours was virtually no change.