• Korean Journal of Food Science and Technology
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• v.23 no.5
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• pp.593-598
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• 1991

The effect of emulsion treatment on the separation of quick-cooking rice kernel after drying and the quality of reconstituted quick-cooking rice made of a Japonica variety were investigated. Among the several stages of emulsion treatment tested, immersion of cooked rice before drying was the most effective on the separation index. Immersion condition of 3 min at $30^{\circ}C$ was found to be the most desirable. Emulsion composed of 5% soybean oil and 0.5% sucrose fatty acid ester (HLB : 9.5) was found to be the most effective to yield the separation index of 86%. By applying the above mentioned emulsion, the separation index was improved by 30 compared with untreated one. The quality of the quick-cooking rice manufactured by the emulsion treatment was found to be as good as untreated one.

• The Korean Journal of Food And Nutrition
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• v.26 no.3
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• pp.421-427
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• 2013

The results of testing general components, physical property and physical function after having made steamed rice cake by adding eggplant, which caters to consumers' tastes are as follows. It showed that when eggplant powder content increased, the moisture content of steamed rice cake with eggplant was decreased. It also showed that the lightness value (L) of steamed rice cake with eggplant powder was the highest as 82.75 in the control group. When eggplant powder content increased, the redness (a) and yellowness (b) were increased. From the results of having measured the antioxidant potential over the steamed rice cake with freezing-drying eggplant powder by DPPH radical elimination, we figured out that it was the lowest as 48.30% in the control group. As more eggplant powder was added, its elimination increased accordingly. As per hardness of steamed rice cake with eggplant, the added group with 7% was revealed as the highest at 0.757. It showed that adhesiveness was the lowest as 30.233 in the control group, and springiness and cohesiveness were on the rise as freezing-drying eggplant powder was increased. Furthermore, softness and chewiness were shown to be high in the added group with eggplant powder of 3, 5%. The evaluation over the overall preference was the highest in 5% added group. Judging from this, adding 3~5% eggplant powder against non-glutinous rice powder is considered an optimal quantity in making steamed rice cake with eggplant.

• Journal of Wetlands Research
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• v.21 no.1
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• pp.43-56
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• 2019

Irrigated and flooded rice paddy contributes to the greenhouse gas emissions (GHG) that affect climate. This in turn affects the supply and reliability of the water needed for rice production. This dynamic makes current rice production methods foreseeably less sustainable over time while having other undesirable effects. Intermittent irrigation by a means of the system of rice intensification (SRI) and alternate wetting and drying (AWD) methods was reviewed to reduce global warming potential (GWP) from 29% to 90% depending on site-specific characteristics from flooded rice paddy and analyzed to be a promising option for enhancing the productivity of water as well, an increasingly constraining resource. Additional benefits associated with the SRI/AWD can be less arsenic in the grain and less degradation of water quality in the run-off from rice paddies. Adoption and expansion of intermittent irrigation of SRI/AWD may require costly public and private investments in irrigation infrastructure that can precisely make irrigation control, and the involvement and upgrading of water management agencies and farmer organizations to enhance management capabilities. Private and public collaboration as a means of earning carbon credit under the clean-development mechanism (CDM) with SRI/AWD for industries to meet as a part of their GHG emission quota as well as a social contribution and publicity program could contribute to adopt intermittent irrigation and rural investment and development. Also, inclusion of SRI and AWD in programs designed under CDM and/or in official development assistance (ODA) projects could contribute to climate-change mitigation and help to achieve UN sustainable development goals (SDGs).

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.1
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• pp.3293-3301
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• 1974

An experimental work was conducted by using a laboratory-made model dryer to investigate the effect of the rate of natural forced-air on the drying rate of rough rice which was deposited in the deep-bed. The dryer consisted of 8 cylinderical containers with grain holding screen at their bottoms, each of which having 30cm in diameter and 15cm in height. The containers were sacked vertically with keeping them air-tight by using paper tape during dryer operation. Two separate layers of containers were operated in the same time to have two replications. The moisture contents of grains within each bins after predetermined period of dryer operation were determined indirectly by measuring the weight of the individual containers. The air-rates were maintained at 6 levels, or 5, 8, 10, 15, 18 and 20 millimenters of static head of water. The roomair conditions during dryer operation were maintained in the range of 10-l5$^{\circ}C$ in temperature and 40-60% in relative humidity. The results of the study are summarized as follows: 1. Drying characteristics of the grains in the bottom layers were approximately the same regardless of airdelivery rates, giving the average drying rate as about 0.35 percent per hour after 40-hour drying period, during which moisture content (w. b.) reduced from 24 percent to about 10 percent. 2. After about 40-hour drying period, the mean drying rates increased from 0.163 percent per hour to 0.263 percent per hour as air-flow rates increased from 5mm to 87.16mm of static head of water. In the same time, the moisture differences of grains between lower and upper layers varied from 12.7 percent at the air rate of 5mm of water head to 7.5 percent at the air-flow rate of 20mn of water head. Thus, the greater the air-flow rate was, the more overall improvement in drying performance was. Additionally, from the result of ineffectiveness of drying grain positioned at 70cm depth or above by the air rate of 5mm of static head of water it may be suggested in practical application that the height of grain deposit would be maintained adequately within the limits of air-rates that may be actually delivered. 3. Drying after layer-turning operation was continued for about 30 hours to test the effectiveness of reducing moisture differences in the thick layers. As a result of this layer-turning operation, moisture distribution through layers approached to narrow ranges, giving the moisture range as about 7 percent at air-flow rate of 5mm head of water, about 3 percent at 10mm head about 2 percent at 15mm head, and less than 1 percent at 20mm head. In addition, from the desirable results that drying rate was rapid in the lower layers and dully in the upper layers, layer-turning operation may be very effective in natural air drying with deep-layer grain deposit, especially when the forced air was kept in low rate. 4. Even though the high rate of air delivery is very desirable for deep-layer natural-air drying of rough rice, it can be happened that the required air delivery rate could not be attained because of limitation of power source available on farms. To give a guide line for the practical application, the power required to perform the drying with the specified air rate was analyzed for different sizes of drying bin and is given in Table (5). If a farmer selects a motor of which size is 1 or {{{{1 { 1} over {2 } }}}} H.P. and air-delivery rate which ranges from 8~10mm of head, the diameter of grain bin may be suggested to choose about 2.4m, also power tiller or other moderate size of prime motor may be recommended when the diameter of grain bin is about 5.0m or more for about 120cm grain deposit.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.439-446
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• 2015

Kimbugak is one of Korea's traditional snacks made of laver. This study was conducted to investigate the physical drying and frying characteristics of kimbugaks made by a pasting & garnishing machine. The drying and frying characteristics should be analyzed to develop a continuous operation system for manufacturing kimbugak because kimbugak has a high moisture content after pasting process. Materials for pasting and garnishing on laver were rice gruel and sesame. The aluminum shelf with square hole was selected as a drying shelf. The recommended size of the square hole type was $1.5mm{\times}1.5mm$ because characteristics of deformation and easy separation from the shelf were excellent at the hole size. The drying time of 2 hours was also recommended with the drying temperature of $70^{\circ}C$ based on the test results such as dried condition (good), moisture conten t (3.7%), deformation (12.1 mm), and shrinkage rate (19.8%). As the frying conditions for dried kimbugaks, recommended oil temperature and frying time were $170^{\circ}C$, 15 seconds, respectively when corn oil was used. In the case of frying for undried kimbugaks, recommended oil temperature and frying time were $210^{\circ}C$, 2 - 3 minutes, respectively for improvement of work efficiency.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.751-755
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• 2006

Physicochemical properties of black rice flours (BRFs) produced under different milling conditions were investigated to explore their applications for various processed rice products. Moisture contents of BRFs after roll milling and subsequent hot-air drying or microwave drying were 10.3% and 14.4%, respectively. The BRFs with jet milling and subsequent hot-air drying or microwave drying showed moisture contents of 7.9% and 7.5%. Mean particle sizes of the BRFs obtained from roll milling, jet milling, and following air-classification were 150, 41.5, and 9.4 ${\mu}m$, respectively. Hunter L value and water soluble index (WSI) of BRFs increased with decreasing particle size, while Hunter a value decreased. Total polyphenol contents of 91.4-115.8 mg/100 g and total amino acids of 75.0-96.4 mg/100 g in three types of BRFs were higher as compared to those (6.3 mg/100 g and 30.5 mg/100 g) of polished rice flour (PRF). Physicochemical properties such as moisture content, color parameter, and WSI have close relationship with the particle size of BRFs prepared under different milling conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.3
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• pp.230-235
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• 1983

Physicochemical properties of instant rice prepared by hot-air drying, alcohol dehydration and freeze-hot air drying were studied. Freeze-hot air drying rice showed the fastest rehydration rate as well as the most desirable textural characteristics. Sensory evaluation suggested that the freeze-hot air drying rice also had more desirable taste, flavor and texture. However, color was more desirable in alcohol dehydrated rice.

• Mycobiology
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• v.42 no.1
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• pp.59-65
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• 2014

Entomopathogenic fungi are promising pest-control agents but their industrial applicability is limited by their thermosusceptibility. With an aim to increase the thermotolerance of Isaria fumosorosea SFP-198, moisture absorbents were added to dried conidial powder, and the relationship between its water potential and thermotolerance was investigated. Mycotized rice grains were dried at $10^{\circ}C$, $20^{\circ}C$, $30^{\circ}C$, and $40^{\circ}C$ and the drying effect of each temperature for 24, 48, 96, and 140 hr was determined. Drying for 48 hr at $10^{\circ}C$ and $20^{\circ}C$ reduced the moisture content to < 5% without any significant loss of conidial thermotolerance, but drying at $30^{\circ}C$ and $40^{\circ}C$ reduced both moisture content and conidial thermotolerance. To maintain thermotolerance during storage, moisture absorbents, such as calcium chloride, silica gel, magnesium sulfate, white carbon, and sodium sulfate were individually added to previously dried-conidial powder at 10% (w/w). These mixtures was then stored at room temperature for 30 days and subjected to $50^{\circ}C$ for 2 hr. The white carbon mixture had the highest conidial thermotolerance, followed by silica gel, magnesium sulfate, and then the other absorbents. A significant correlation between the water potential and conidial thermotolerance was observed in all conidia-absorbent mixtures tested in this study (r = -0.945). Conidial thermotolerance in wet conditions was evaluated by adding moisturized white carbon (0~20% $H_2O$) to conidia to mimic wet conditions. Notably, the conidia still maintained their thermotolerance under these conditions. Thus, it is evident that conidial thermotolerance can be maintained by drying mycotized rice grains at low temperatures and adding a moisture absorbent, such as white carbon.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.357-370
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• 1982

Recent concern regarding price and availability of fossil fuels has spurred the interest in alternative sources for farm crop drying. Among the available options such as biomass energy, wind power, nuclear energy and solar energy etc., the increasing attention is being directed to the utilization of heat from solar energy especially for farm crop drying. Even though solar energy is dispersed over a large land area and only a relatively small amount of energy can be simply collected, the advantages of solar energy is that the energy is free, non-polluting. The study reported here was designed to help supply the informations for the development of simple and relatively inexpensive solar warehouse for farm crop drying and storage. Specifically, the objectives of this study were to determine the performance of the solar collector fabricated, to compare solar supplemented heat drying with natural air drying and to develop a simulation model of temperature in stored grain, which can be used to study the effects due to changes in ambient air temperature. For those above objectives, solar collector was fabricated from available materials. Corrugated steel galvanized sheet, painted flat black, was used as absorbers and clear 0.2mm polyethylene sheet was the cover material. The warehouse for rough rice drying and storage was constructed with concrete block, and the solar collector was used as the roof of warehouse instead of original roofing system of it. The results obtained in this study were as follows: 1. The thermal efficiency of the solar collector was average 26 percent and the overall heat transfer coefficient of the collector was approximately $25kJ/hr.m^2\;^{\circ}K$. 2. Solar heated air was sufficient to dry one cubic meter of rough rice from 23.5 to 15.0 percent in 7 days and natural air was able to dry the same amount of rough rice from 20.0 to 5 percent in l2 days. 3. Drying with solar heat reduced the required drying time to dry the same amount of rough rice into a half compared to natural air drying, but overdrying problems of the bottom layer were so severe that these problems should be thoroughly analyzed. 4. Simulation model of temperature in stored grain was developed and the results of predicted temperature agreed well with test results. 5. Based on those simulated temperature, changes in the grain-temperature were a large at the points of the wallside and the damage of the grain would be severe at the contact area of wall.

• Journal of Biosystems Engineering
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• v.4 no.2
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• pp.65-83
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• 1979

Low-temperature drying systems have been extensively used for drying cereal grain such as shelled corn and wheat. Since the 1973 energy crisis, many researches have been conducted to apply solar energy as supplemental heat to natural air drying systems. However, little research on rough rice drying has been done in this area, especially very little in Korea. In designing a solar drying system, quality loss, airflow requirements, temperature rise of drying air, fan power and energy requirements should be throughly studied. The factors affecting solar drying systems are airflow rate, initial moisture content, the amount of heat added to drying air, fan operation method and the weather conditions. The major objectives of this study were to analyze the effects of the performance factors and determine design parameters such as airflow requirements, optimum bed depth, optimum temperature rise of drying air, fan operation method and collector size. Three hourly observations based on the 4-year weather data in Chuncheon area were used to simulate rough rice drying. The results can be summarized as follows: 1. The results of the statistical analysis indicated that the experimental and predicted values of the temperature rise of the air passing through the collector agreed well. 2. Equilibrium moisture content was affected a little by airflow rate, but affected mainly by the amount of heat added, to drying air. Equilibrium moisture content ranged from 12.2 to 13.2 percent wet basis for the continuous fan operation, from 10.4 to 11.7 percent wet basis for the intermittent fan operation respectively, in range of 1. 6 to 5. 9 degrees Centigrade average temperature rise of drying air. 3. Average moisture content when top layer was dried to 15 percent wet basis ranged from 13.1 to 13.9 percent wet basis for the continuous fan operation, from 11.9 to 13.4 percent wet basis for the intermittent fan operation respectively, in the range of 1.6 to 5.9 degrees Centigrade average temperature rise of drying air and 18 to 24 percent wet basis initial moisture content. The results indicated that grain was overdried with the intermittent fan operation in any range of temperature rise of drying air. Therefore, the continuous fan operation is usually more effective than the intermittent fan operation considering the overdrying. 4. For the continuous fan operation, the average temperature rise of drying air may be limited to 2.2 to 3. 3 degrees Centigrade considering safe storage moisture level of 13.5 to 14 perceut wet basis. 5. Required drying time decrease ranged from 40 to 50 percent each time the airflow rate was doubled and from 3.9 to 4.3 percent approximately for each one degrees Centigrade in average temperature rise of drying air regardless of the fan operation methods. Therefore, the average temperature rise of drying air had a little effect on required drying time. 6. Required drying time increase ranged from 18 to 30 percent approximately for each 2 percent increase in initial moisture content regardless of the fan operation methods, in the range of 18 to 24 percent moisture. 7. The intermittent fan operation showed about 36 to 42 percent decrease in required drying time as compared with the continuous fan operation. 8. Drymatter loss decrease ranged from 34 to 46 percent each time the airflow rate was doubled and from 2 to 3 percent approximately for each one degrees Centigrade in average temperature rise of drying air, regardless of the fan operation methods. Therefore, the average temperature rise of drying air had a little effect on drymatter loss. 9. Drymatter loss increase ranged from 50 to 78 percent approximately for each 2 percent increase in initial moisture content, in the range of 18 to 24 percent moisture. 10. The intermittent fan operation: showed about 40 to 50 percent increase in drymatter loss as compared with the continuous fan operation and the increasing rate was higher at high level of initial moisture and average temperature rise. 11. Year-to-year weather conditions had a little effect on required drying time and drymatter loss. 12. The equations for estimating time required to dry top layer to 16 and 1536 wet basis and drymatter loss were derived as functions of the performance factors. by the least square method. 13. Minimum airflow rates based on 0.5 percent drymatter loss were estimated. Minimum airflow rates for the intermittent fan operation were approximately 1.5 to 1.8 times as much as compared with the continuous fan operation, but a few differences among year-to-year. 14. Required fan horsepower and energy for the intermittent fan operation were 3. 7 and 1. 5 times respectively as much as compared with the continuous fan operation. 15. The continuous fan operation may be more effective than the intermittent fan operation considering overdrying, fan horsepower requirements, and energy use. 16. A method for estimating the required collection area of flat-plate solar collector using average temperature rise and airflow rate was presented.