• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.25-30
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• 2005

This experiment was carried out for the improvement of drying schedules for 50 mm-thick Japanese red pine (Pinus densiflora Sieb. et Zucc.) lumber. Drying rates were analyzed comparatively after drying to 15% of final moisture content through the applications of conventional kiln drying schedule, time schedule, continuously rising temperature schedule, and drying rate schedule. As results drying rate of 50 mm-thick red pine lumber was 0.53%/hr with conventional kiln drying schedule, 0.9%/hr with time schedule, 2.29%/hr with continuously rising temperature schedule, and 1.52%/hr with drying rate schedule, respectively.

• Korean Journal of Food Science and Technology
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• v.21 no.5
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• pp.655-661
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• 1989

Optimal drying conditions consisting of air temperature and relative humidity were searched by the simulation-optimization technique for minimizing quality changes in red pepper drying. Optimized drying conditions were analysed in the viewpoint of quality change kinetics and effects of control variables on the state variables. Optimal drying conditions were nearly same in both cases for carotenoid maximization and browning minimization. In two staged optimized drying, relative humidity took a lower search limit of about 10%, and air temperature in the first stage was near the lower limit of $50^{\circ}C$ and in second stage increased to a higher temperature varying with total drying time and stage changing time. Response surface analysis of time invariable drying confirmed the location of the optimal point lying on the vertex of lower limit humidity and a lowest drying temperature which ensures to attain target moisture of 0.2g water/g dry solid. Two stage drying can attain the higher objective function of quality by 3-5% than time invariable drying for shorter total drying times.

• Journal of Practical Agriculture & Fisheries Research
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• v.20 no.1
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• pp.67-74
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• 2018

This experiment was conducted to develop a healthy tea by fumigation, low temperature drying, drying and instant immersion using flowers of Robinia pseudoacacia L. that bloom in May in all regions of Korea. The drying was drying after fumigation treatment, low temperature drying, drying and instant immersion. The color of the flowers, beverage color, the sugar content, and the taste of the beverage were measured after changing the weight of the flowers. The change in the weight of flower tea was 11% ~ 12.5% of the body weight. The change in the color of the flowers appeared to be the lightest brown in the treatment of drying, and the other treatment area became turbidity white. The color of the beverage was yellowish from the tea treated with drying and became pale yellow when fumigation, low temperature drying and instant immersion. Sugar content was highest at 2.9brix from the drying and 2.6-2.7brix at the other three treatments. The taste was the best in the drying treatment, and the instant taste dipped in the tastes.

• The Korean Journal of Food And Nutrition
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• v.13 no.2
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• pp.152-157
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• 2000

In order to select the optimum drying method for the production of cinnamon extract, water extract and 70% ethanol extract of cinnamon were prepared. And then several drying method of oven drying, vacuum evaporation, spray drying and freeze drying were performed. Content of cinnamic acid, cinnamic aldehyde, eugenol, tannin and free sugar, and antioxidant activity, degree of browning, pH, color value, turbity and solubility were compared. In water extract, contents of cinnamic acid, cinnamic aldehyde, eugenol were 29.45mg/100g, 94.86mg/100g, 120.75mg/100g and decreased to 4.76%∼44.21%, 5.30%∼48.05%, 3.66%∼21.83% by oven dyring, vaccum drying, spray drying respectively, but freeze drying showed a little decrease of those components. In 70% ethanol extract, effectual components decreased to 76.05%∼88.38% and 26.86%∼78.76% by freeze drying and vacuum evaporation respectively. Antioxidant activity decreased by drying and decreasing rate in 70% ethanol extract was lower than water extract. Degree of browning increased as the drying temperature increased. Tannin and free sugars were little affected by drying temperature. Solubility decreased in oven drying and 70% ethanol extract. Overall data suggested that optimum drying methods of cinnamon extract were freeze drying in case of water extract and freeze drying and vaccum drying in case of 70% ethanol extract.

• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.1-8
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• 1998

Western redcedar timber, 26 by 26cm in cross section and by 200cm long, was dried in a laboratory radio-frequency/vacuum kiln under 65torr of ambient pressure and a fixed frequency of 6.78MHz for the potential rapidly dry large timber. All process data were collected and saved in a computer through a data acquisition system. The temperature in the middle of timber was higher than temperature at the quarter point of timber length and thickness. Temperature gradients developed in the longitudinal and transverse direction of timber. The pressure in the middle of timber was higher than pressure at the quarter point of timber length. The pressure in the middle of timber was lower in the early stage of drying, and higher in the latter stage of drying than pressure at the quarter point of timber thickness. Power density was very highest during heating period and then gradually decreased. The drying curve was approximately linear and the total drying time was 27 hours from an initial moisture content(MC) of 48.6 percent to a final Me of 19.2 percent with only a few mild internal checks in the middle location of timber.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.

• Journal of Biosystems Engineering
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• v.18 no.2
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• pp.122-132
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• 1993

Effects of physical properties of garlic paste and freeze dry control parameters on the sublimation drying time were investigated to verify optimal operating method in freeze drying. A mathematical model of freeze drying by sublimation was suggested and used to estimate the drying time of garlic paste. Under various conditions, the drying time of garlic paste was calculated using the computer program for the suggested model. Among the physical properties of garlic paste, melting temperature was evaluated the most important factor in affecting the drying time. In supplying methods of the required heat energy for sublimation, it would be the best way to control the upper plate temperature and the lower plate temperature independently.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1293-1297
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• 2009

In this study, drying kinetics of onion slices was examined in a laboratory scale vacuum dryer at an air temperature in a range of $50-70^{\circ}C$. Moisture transfer from onion slices was described by applying the Fick's diffusion model, and the effective diffusivity was calculated. Temperature dependency of the effective diffusivity during drying process obeyed the Arrhenius relationship. Effective diffusivity increased with increasing temperature and the activation energy for the onion slices was estimated to be 16.92 kJ/mol. The experimental drying data were used to fit 9 drying models, and drying rate constants and coefficients of models tested were determined by non-linear regression analysis. Estimations by the page and Two-term exponential models were in good agreement with the experimental data obtained.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.2
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• pp.74-84
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• 2005

The objectives of this study was to investigate the improvement of thermal kinetics for disposal of sewage sludge using thermal wind drying. The operational parameters varied are the temperature of $130{\sim}170^{\circ}C$ and evaporation velocity WD. Important parameters effect on thermal kinetics for evaporation of water in sewage sludge studied include the drying time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. The saturation point of water evaporation was observed at the drying time of 60 min in conditions of drying temperature $170^{\circ}C$ and drying time of 120 min by drying temperature $130^{\circ}C$ and WD=0.95 m/s. Operation at drying temperature of $170^{\circ}C$ led to higher rate of evaporation than those 130, $150^{\circ}C$ at WD=1.0 m/s and WD=1.0 m/s was higher than WD=0.5 m/s at drying temperature of $130^{\circ}C$.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.681-686
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• 2002

In the industrial field, the theory of drying process is different from the practical application, and it is effective to reduce energy by recirculation of the heat of exhausting gas. But the study of this field may not be performed still. The cure properties of the urea resin moulding compounds was investigated according to drying temperature, drying time, recycle rate of exhausting gas and moulding temperature in the process of drying and moulding. We obtained the following results; water content of material decreases with increasing drying time and drying temperature, and the rate of drying also decreases with increasing recycle rate of exhausting gas. Specially, The cure fluidity of the urea resin moulding compounds decreases, with increasing drying temperature, recycle rate of exhausting gas and moulding temperature. And the correlation equations on water content and cure fluidity of the urea resin moulding material were obtained through a regression analysis of experimental data.