• Journal of Powder Materials
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• v.10 no.6
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• pp.436-442
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• 2003

The magnetic Nd-Fe-B powders were prepared by a thermochemical method, consisting of the processes of spray-drying, debinding, milling, H$_2$-reduction, Ca-reduction, and washing. The optimum process conditions were studied by microstructural and thermal analysis. The resultant Nd-Fe-B powder was spherical with the size of 1 ${\mu}{\textrm}{m}$. Effects of the process parameters of each step on the microstructure of the powders were investigated, and their magnetic properties were evaluated.

• Food Science and Biotechnology
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• v.16 no.2
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• pp.187-192
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• 2007

The objectives of this study were to examine changes in the color and antioxidant compounds of paprika powder under various conditions, as well as to establish the suitable conditions for drying and storage. Paprika was dried using the following methods: freeze-drying, vacuum drying, far infrared-ray drying, and hot-air drying. Measurements of the moisture content, color pigments, and antioxidant compounds (total carotenoids, capsanthin, ascorbic acid, and total polyphenols) were completed during 120 days of storage at 4 and $30^{\circ}C$. We found that drying methods, storage temperatures, and packaging materials affected the American Spice Trade Association (ASTA) and Hunter color values, as well as the antioxidant content of paprika powder. There was a high correlation (r=0.87, p<0.01) between the ASTA color and the $a^*/b^*$ value. The loss of red color was closely related to the reduction of moisture content (r=0.81, p<0.01) during storage. Drying paprika with a low temperature in the absence of air resulted in better retention of the carotenoids and ascorbic acid. Also, as the retention of the carotenoids and ascorbic acid increased, the stability of the red pigment increased. Freeze-drying was found to be the most suitable drying method for the stability of the antioxidant compounds and red pigment.

• Journal of Biosystems Engineering
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• v.15 no.3
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• pp.230-243
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• 1990

This study was conducted to investigate the possibility of application of an infrared drying to drying process for red pepper. The performance of seramic heaters and the variation of temperature and moisture content of red pepper were analyzed during an infrared drying of red peppers. Also, the quality of dried red pepper was analyzed. The following results were obtained from this study. 1. The surface temperature of infrared heaters and the rising time required for steady state were mainly affected by electrical power consumed. 2. The heat energy required for heating red pepper was proposed to be calculated by the equation in terms of enthalpy of air and net heat flux by infrared heater in a drying chamber. The statistical model for net heat flux was developed. 3. The performance of the infrared heater used for heating red pepper was much affected by the distance of radiation, and the difference of temperatures appeared between the radiated surface and the inside of red pepper. 4. Electrical capacity of the infrared heater had a significant effect on the heating of red pepper. However, the effect of shape of heater on heating was not significant. 5. The variation of temperature of red pepper largely appeared in the range of 30 to 60% (db) in moisture content. The temperature of red pepper was almost constant at low moisture content. 6. The temperature of red pepper and heating time had significant effects on the quality for radiant heating. 7. When the electrical capacity of infrared heater and the distance of radiation are carefully designed in a dryer with the insulated drying chamber, infrared drying might be very effective in red pepper drying.

• Journal of the Korean Ceramic Society
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• v.31 no.12
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• pp.1467-1474
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• 1994

The effects of the dispersion, drying, and binder burning-out on the green-microstructures of gelcasted alumina were studied. The slip consisting of 55 vol% alumina powder and 5 wt% organic materials was well-dispersed by adding 0.28 wt% polyelectrolyte polymer. Green bodies were dried at >85% relative humidity at room temperature. Green-microstructures were observed to be depended on the heating rate during binder burnout. Constant drying rate was not observed in drying process of gelcasted alumina. Sintered body showed its relative density higher than 99% when it was sintered at 1$600^{\circ}C$ for 2 hours.

• Journal of the Korean Society of Food Culture
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• v.18 no.5
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• pp.437-442
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• 2003

This study was conducted to confirm the effect of drying method on quality of popped rice for making salyeotgangjung(popped rice lump with malt syrup) in process of drying gelatinized rice. The drying were performed at dry oven or convection oven, at $30^{\circ}C,\;50^{\circ}C\;and\;105^{\circ}C$, respectively. There were not significant differences in the hardness of popped rice among the drying methods. The dry at $30^{\circ}C$ constant in dry oven showed higher popping rate, good external surface, uniformed and well developed internal cell size. The dry at $30^{\circ}C$ in convection oven and $50^{\circ}C$ constant temperature in dry oven showed low expansion and poor external surface, respectively. In conclusion, the drying at $30^{\circ}C$ in non-convection oven had the highest quality of popped rice for salyeotgangjung.

• 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.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.636-641
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• 2008

Heat pump drying has a great potential for energy saving due to its high energy efficiency in comparison to conventional air drying. The heat pump dryer is usually operated at the temperature less than $50^{\circ}C$ and the drying temperature is limited to the operating temperature of the heat pump system. In order to increase the drying temperature, the special box-type heat pump dryer has been developed. The dryer uses the two-cycle heat pump system which has the two heat pump cycles for high and low temperature heating. The high temperature cycle uses the refrigerant 124 to get the temperature greater than $80^{\circ}C$ and the low temperature cycle uses the refrigerant 134a. The drying experiment has been carried out to figure out the performance of the dryer with the selected drying material.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.4
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• pp.741-746
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• 2004

Drying of raw ginseng root down to 35% moisture content required for extrusion process. There were two kinds of pre-treatments of raw ginseng root which were chopping and whole-root ginseng before frying at 80, 100 and 12$0^{\circ}C$. Drying rate and physicochemical properties of dried ginseng were evaluated to determine optimum drying temperature for extrusion process. Drying time at 8$0^{\circ}C$ to decrease to 35% moisture was 6.5 hr and ginsenoside content in dried ginseng at 8$0^{\circ}C$ was lower than that of dried ginseng at 100 and 12$0^{\circ}C$. Drying time at 100 and 12$0^{\circ}C$ to decrease to 35% moisture was 5.5 and 3.5 hr and redness of dried ginseng powder was 5.20 and 7.23 respectively. Browness and redness of dried ginseng extract from 75% ethylene were significantly increased with the increase in drying temperature. Ginsenosides Rb1, Rb2, Rc, Rd, Rg1 and total saponin were also increased with the increase in drying temperature from 8$0^{\circ}C$ to 10$0^{\circ}C$, however, those were not significantly different with drying temperature at 100 and 12$0^{\circ}C$. Drying temperature for extrusion process can be optimal at 10$0^{\circ}C$.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.41-46
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• 2017

This study aims to select suitable co-solvents and to obtain optimal process conditions in order to improve process efficiency and productivity through experimental results obtained under various experimental conditions for the etching and rinsing process using liquid carbon dioxide and supercritical carbon dioxide. Acetone was confirmed to be effective through basic experiments and used as the etching solution for MEMS-wafer etching in this study. In the case of using liquid carbon dioxide as the solvent and acetone as the etching solution, these two components were not mixed well and showed a phase separation. Liquid carbon dioxide in the lower layer interfered with contact between acetone and Mems-wafer during etching, and the results after rinsing and drying were not good. Based on the results obtained under various experimental conditions, the optimum process for treating MEMS-wafer using supercritical CO2 as the solvent, acetone as the etching solution, and methanol as the rinsing solution was set up, and MEMS-wafer without stiction can be obtained by continuous etching, rinsing and drying process. In addition, the amount of the etching solution (acetone) and the cleaning liquid (methanol) compared to the initial experimental values can be greatly reduced through optimization of process conditions.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.665-670
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• 2001

The purpose of this study is to develop a new type dryer, which is to proceed mixing and drying of wet-materials at the same time and drying process is carried out in a closed system. In this drying system, thermal contact occurs, when a fluidized zone is created by paddle mechanism. Accordingly, wet-materials is dried in a short time without any damage. Also wet-materials could be dried uniformly to low moisture contents. It is suitable to dry a small quantity of multi-kind materials. And drying process is carried out in a closed system, so as for environmental pollution dust not to be emitted into the atmosphere. Accordingly, it could be used to dry not only food and chemical materials, but also environmental pollution materials.