• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.13 no.3
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• pp.168-182
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• 1984

For the purpose of drying high moisture rough rice effectively, from the view point of pre-drying, some basic experiments of fluidized bed drying of rough rice were carried out. The minimum fluidization velocities $(U_{mf})$ for both rough rice and glass bead were analyzed to find out fluidizing characteristics. The main results obtained were as follows ; 1) Minimum fluidization velocity of rough rice and glass bead were 2.01m/s and 4.07m/s, respectively, when using the distributor with $16\%$ opening ratio. 2) $U_{mf}$ calculated by Shirai's empirical equation and that calculated by Wen's modified equation were inconsistent with experimental data, while $U_{mf}$ calculated by Ergun's equation was consistent with the experimental data. 3) The following equations, on the basis of Leva's equation, were obtained. $$C_{mf}=1.19\times10^{-4}(Re_p)^{-0.0318)\;(rough rice)$$ $$C_{mf}=1.02imes10^{-4}(Re_p)^{-0.0047)\;(glass bead)$$

• Journal of Biosystems Engineering
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• v.29 no.6 s.107
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• pp.495-500
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• 2004

This study was performed to develop thin layer drying equations for low temperature. Thin layer drying tests of short grain rough rice were conducted at three low temperature levels of 15, 25, $35^{\circ}C$ and two relative humidity levels of 30, $50\%$, respectively. The measured moisture ratios were fitted to the selected four drying models (Page, Thompson, Simplified diffusion and Lewis model) using stepwise multiple regression analysis. The overall drying rate increased as the drying air temperature was increased and as relative humidity was decreased, but the effect of temperature increase was dominant. Half response time (Moisture ratio=0.5) of drying was affected by both drying temperature and relative humidity at drying temperature of below $25^{\circ}C$, but at $35^{\circ}C$ was mainly affected by drying temperature. The results of comparing coefficients of determination and root mean square error of moisture ratio for low drying models showed that Page model was found to fit adequately to all drying test data.

• Journal of Biosystems Engineering
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• v.5 no.1
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• pp.15-23
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• 1980

Natural-air drying systems have been extensively used for cereal grains, and many researches on the systems have been conducted in foreign countries. However, little research on drying rough rice with natural air has been done. Especially . little research on natural air drying of rough rice based on weather data has been done in Korean. The objective of this study was to present fundamental data for estimating optimum requirements and basic information available for natural air drying of rough rice based on the weather data . The weather data analyzed in this study were the 10-year (1969 to 1978) record of air temperatures, wet-bulb temperatures and relative humidities, which were three-hourly observations in Taegu area. The results of this study are summarized as follows ; 1 From the results of weather data analysis the average air temperature was about $14.8^\circ$and the average relative humidty 67.5% . Average equilibrium moisture content appeared to be 13.8 percent on wet basis, which showed great potential for natural air drying in Taegue area in October. 2. Possible fan operation time based on the equilibrium moisture content of 15% on wet basis was about 14 hours a day during October in Taegu area. Probabilities of possible drying days based on minimum time available for drying in a day were analyzed. 3. Minimum air flow requirements based on the worst year were determined for different fan operation methods and initial moisture contents.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.4
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• pp.345-350
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• 1991

Rough rice samples of Chucheongbyeo, Bongkwangbyeo and Hwaseongbyeo were collected by the National Agricultural Products Inspection Office. Drying methods of rough rice were sun drying and forced ventilation drying by an oven dryer and temperature of the oven dryer was set to 43, 60, 70, or 8$0^{\circ}C$. Moisture content of samples was reduced from ca. 20% to 15% at the end of drying, and additionally to 12.5 % for the drying at 8$0^{\circ}C$. Characteristics related to rice grain quality, milling recovery, ratio of broken and cracked rices, percentage of germination, and sensory scores of the cooked rices were evaluated. Yielding percentage of brown rice and polished rice remarkably decreased by drying at 8$0^{\circ}C$. Percentages of cracked rice and broken rice were within the criterion of the second grade government brown rice (20%) only in the sun dried and the rices dried at 43$^{\circ}C$, on the basis of damaged rice, opaque kernel rice and colored rice. Broken rice percentage of the polished rice was within the criterion for the standard of government rice (5%) in the sun dried and the rices dried at 43$^{\circ}C$. Germination percentage of rough rice was higher than 80% in sun drying and drying at 43$^{\circ}C$, but remarkably decreased by drying rice at 6$0^{\circ}C$ and over. Sensory palatability of the cooked rice decreased with increase in drying temperature. The present governmental method of judging rough rice on the basis of moisture content and appearance of the rough rice appears to be improved to include the ratio of broken and cracked rices.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.877-885
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• 1993

Three types of solar grain dryers, namely , the solar grain bin dryer, the solar greenhouse rotary drum dryer and small scale solar green house tray dryer, have been tested. The results showed that each type of solar grain dryer has its feature. These solar drying units have three main advantages : (1) Required commercial energy to remove 1Kg moist from rough rice is only 5.3% to 15.8% of the energy consumed by common heated dryer : 2) The area of solar drying system is only about 10% of the area of the sunny ground to give equal drying capacity ; (3) There are good drying quality in the moisture uniform , germination percentage, and grain color.

• Korean Journal of Food Science and Technology
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• v.38 no.4
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• pp.506-512
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• 2006

We investigated changes in the physicochemical characteristics and functional components of the Saengsik cereal grains-milled rice, brown rice, glutinous rice, and barley- by washing with electrolyzed water. There were no changes in the composition of all cereal grains that was dried with hot-air and freeze-dried after being washed with electrolyzed water. The L and a values were not affected by drying in milled rice, brown rice, glutinous rice, or barley, but the b value increased in milled rice and glutinous rice-this increase was greater with hot-air drying than with freeze-drying. The dietary fiber content of the all cereals increased with hot-air drying. The niacin content decreased in all cereals; the extent of this change was greater with hot-air drying than with freeze-drying. The ${\beta}-glucan$ content of barley was higher in samples that underwent freeze-drying than in those treated by hot-air drying, but was not affected by washing with electrolyzed water. Thus, other than a change in color for milled and glutinous rice, no changes in the physicochemical characteristics and functional components these products were observed with freeze-drying. Data indicate that the electrolyzed water washing could be effectively used as pasteurization step in the uncooked cereal grains.

• Journal of Biosystems Engineering
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• v.31 no.4 s.117
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• pp.349-354
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• 2006

This study was performed to evaluate the performances for a concurrent flow rice dryer of pilot scale with devices for circulating rice. The pilot scale dryer with the capacity of 700 kg was developed to obtain design informations for the development of actual scale dryer of holding capacity of 10 tons. Three drying tests were conducted at two temperature levels of $100^{\circ}C\;and\;120^{\circ}C$, and two air flow rates levels of $28.5cmm/m^2\;and\;57.1cmm/m^2$. Drying conditions for Test-1, Test-2 and Test-3 were $100^{\circ}C\;-28.5cmm/m^2,\;120^{\circ}C-28.5cmm/m^2\;and\;120^{\circ}-57.1cmm/m^2}$ respectively. Drying rates were 0.73%(w.b./h) for Test-1, 0.90%(w.b./h) for Test-2 and 1.46%(w.b./h) for Test-3. The crack ratios of brown rice after drying ranged from 2.4% to 8.4%, and increased with the increase of drying rate and airflow rate. The energy consumptions were from 6,225 kJ/kg to 6,993 kJ/kg which was higher than that of conventional cross-flow rice circulating type dryer used in Korea. This results were due to the lower ambient air temperatures of $4.5^{\circ}C\;to\;13.4^{\circ}C$ during drying tests.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.4
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• pp.234-239
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• 2013

This study investigated the effects of drying methods and drying time on the changes in anthocyanin content in colored barley. Colored barley cultivar Boanchalbori was harvested at a time when the anthocyanin content was the most and dried in afield. The harvested barley was then treated by two methods, sun drying and shade drying, for 4, 8, 24, and 32 h. The moisture content of the sun-dried barley decreased slightly faster than shade-dried samples, but the difference was not statistically significant. Chemical analysis indicated that the samples dried under shaded conditions had slightly higher crude fiber and lower nitrogen free extract, but the difference was not statistically significant. There was no difference in the total digestible nutrients between the two methods. In the case of sun-dried barley, the anthocyanin content decreased compared to the control and shade-dried samples after drying for 4 h (p < 0.05), was maintained at a constant level at 24 h, and then decreased at 32 h. In case of shade-dried barley, the anthocyanin content decreased gradually with the drying time, and a significant decrease was found at 24 h of drying (p<0.05) as compared to the control. The shade-dried method was more successful in reducing anthocyanin loss than the sun-dried method (p<0.05). There was a slight decrease in 1,1-Diphenyl-2-Picrylhydrazyl radical scavenging with drying time in the shade-dried method, and a significant decrease after 4 h with the sun-dried method. These results showed that covering with a two-layer awning was advantageous to dry colored barley in the field conditions.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.625-630
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• 1999

This work was to study drying characteristics of the brown rice koji, an enzymic health food, using microwave under vacuum. Cooked brown rice was inoculated with Aspergillus oryzae and incubated at $32^{\circ}C$ for 6 days. The brown rice koji was dried by different drying methods: microwave vacuum drying, hot air drying, vacuum drying and freeze drying. Each drier except freeze drier was set to maintain the sample temperature at $40^{\circ}C$. During microwave vacuum drying, the sample reached $40^{\circ}C$ much faster (within $5{\sim}10\;min$) and was dried much faster (2 hrs) than the other drying methods. The initial drying rate of microwave vacuum drying was ten times faster than that of hot air drying. The microwave vacuum drying produced a dry sample of the highly retained enzymic activity, followed by freeze drying, vacuum drying, and hot air drying.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.227-232
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• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) of moisture contents to 16.7%(w.b), by prototype dryer and the average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to a conventional natural air dryer in which grains were not mixed during drying periods. The dryer performance evaluation index was 738.3kJ/(kg.water), which was more effective than that of grain circulation type hot air dryer(3,500∼5,000 kJ/kg.water)