• Proceedings of the Korean Society of Crop Science Conference
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• 2019.09a
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• pp.21-21
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• 2019

Approximately 80% of rice field in Africa conducts in rainfed (Nishimaki 2017). The rice is damaged by water stress because fields like rainfed lowland repeat drying and humidity of soil because of impossible water control. Then water stress is one of the major limiting factors for decreasing rice yield. So, in initial growth stage, quick and efficient root development is useful way to avoid drought stress by getting water from deeper soil layer with roots elongation as the hypothesis. Daniel et al (2016) reported that NERICA1 and NERICA4 show different patterns of root plasticity for drought stress. NERICA1 has greater development of lateral root in shallow soil layer, while NERICA4 has greater development in deep root elongation to underground. This study was aimed to evaluate the effect of root development in initial growth stage on growing NERICA1 and NERICA4 under different soil moisture condition in rainfed lowland rice field. They were grown in same water condition until 35 days after sowing (35DAS), and after that each varieties were separated in dry and wet condition. The rice plants were grown until 60DAS. The results of soil moisture, the root extension angle, shoot dry weight and bleeding ratio showed that NERICA4 can mitigate dry stress from surface soil compered to NERICA1.

• The Korean Journal of Community Living Science
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• v.23 no.4
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• pp.537-552
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• 2012

This study was conducted to investigate the quality characteristics of cooked rice with cereals frequently consumed in Korea by blending ratio. Seven kinds of cereals, white rice, glutinous barley, brown rice, black rice, glutinous rice, glutinous foxtail millet and proso millet, were chosen for the study. According to the results from rapid viscosity analyzer, glutinous barley had the lowest pasting temperature($66.55^{\circ}C$) and black rice had the highest values in the peak(231.77 RVU), trough(162.25 RVU), final viscosity(295.81 RVU) and set back(64.05 RVU)(p<0.05). Water absorption rate by soaking time for black rice and brown rice was increased only 18.77% and 14.57%, respectively, even after 120 minutes, whereas those of other cereals were increased up to 20.28~39.32% after 50 minutes. The pasting characteristics of white rice blended with cereals tended to be lower than white rice in the peak, trough, and final viscosity. Textural property of cooked white rice blended with black rice, brown rice, and glutinous foxtail millet showed a significantly higher value for hardness than that of cooked white rice only(p<0.05). The most preferred blending ratio of the respective cereals was 25% for glutinous barley, 10% for black rice, brown rice and proso millet, and 5% for glutinous foxtail millet and glutinous rice in the sensory evaluation for overall quality, but there were no significant differences except glutinous barley, brown rice and glutinous foxtail millet.

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.506-513
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• 2006

The effects of ultrasound stimuli on the germination and sprout growth of brown rice were investigated. Ultrasound was applied to brown rice at the frequencies of 28, 40, and 60 kHz before germination test and it was germinated in three methods (Type I, II and III). Type I was to soak brown rice into water for 60 hours. Type II was to expose brown rice to air for 48 hours after soaking them into water for 12 hours. Type III was a repetitive method of water-soaking and air exposure for 12 hours respectively. The most effective method for the germination was Type III without ultrasound. However, Type I was a best method after ultrasound treatment. As power of ultrasound increased, sprouts grew faster after brown rice were treated in 40%, 70%, and 100% power (0.137, 0.241, and 0.344 $W/cm^2$) at 40 kHz. The good treatments for fast sprout growth of brown rice at each frequency were the 28 kHz-10min group, the 40 kHz-5min group, and the 60 kHz-20min group of Type I. The best effective treatment was the 40 kHz-5min group at 0.344 $W/cm^2$ and at that condition the time required for sprout growth of 2.5 m was 51.9 hours. The ultrasound stimuli was very effective in the beginning of the rice germination, and the germination ratio was more than 95% in all ultrasound treatments.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.644-649
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• 1996

The purpose of this study was to investigate the relationship between physicochemical properties and optimum amount of added water for cooking in the preparation of Korean cooked rice (bab). Seven different kinds of rice samples were tested for their chemical and physical properties in relation to the eating quality after cooking with various amounts of water added. The amylose content and water content of rice did not show significant correlation with the amount of added water for optimum cooking. The width of rice kernel, expansion ratio, amylogram maximum viscosity showed significant correlation with the optimum ratio of added water for cooking.

• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.169-175
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• 2005

This study was carried out to investigate the effects of irrigation water pollution on the yield and grain quality of rice. It acquires fundamental data to set up water quality standards for irrigation and produce agricultural safety products. The correlations of BOD, T-N, T-P, pH, ECw of the irrigation water with yield, grain appearance quality, and the protein content were evaluated. The field and pot experiments were conducted by using Japonica of Oryza sativa L. during 2 years. BOD concentration in irrigation water effects strongly on grain appearance quality and yield of rice. T-N in irrigation water has strong effect on the yield, appearance, and quality of rice. T-P concentration in irrigation water have not any correlation with yield and quality of rice. pH showed strongly negative correlation with maturity ratio(MTR), 1000 grain weight(TGW), and yield of rice(YLD) as r=-0.803~-0.828(p<0.001) and have no effect on the appearance quality of rice. $EC_w$ indicating salt content showed strongly negative correlation with MTR, TGW, number of grains per panicles(NGP), and number of panicles per unit area(NPM) as r=-0.759~-0.798, and with YLD as -0.753.

• Journal of Biosystems Engineering
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• v.12 no.4
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• pp.31-43
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• 1987

This study was performed to develop a hot water boiler system with small scale automatic rice hull furnace for the multi-purpose use in the farm. For the experiment a prototype hot water boiler system with rice hull furnace was fabricated, which was equipped with automatic hull feeder, igniter and ash removal device. Optimum operational conditions of the prototype: system were analyzed. The results arc summarized as follows. 1. The temperature measured right above the burning surface should be higher than $500^{\circ}C$ combustion. 2. The top zone of the combustion chamber was the most suitable location of the thermocouple to pick up the control temperature for the automatic operation of the rice hull furnace. 3. The content of carbon monoxide in the flue gas was increased with the filling height of burning material but it was less than 0.3 percent in volume in this experiment. When the filling height was expressed as the ratio of rice hull feed rate to the volume of the combustion chamber above the burning surface, the optimum ratio was about $150kg/m^3-h$. 4. The combustion efficiency of the prototype was higher than 95 percent when the feed rate was 1.1 to 2.3 kg/h and moisture content of rice hull was 22.4 percent (w.b.) or less. 5. It was estimated that the optimum operational conditions of the system were 1.3 to 2.0 kg/h in feed rate, 70 to 100 percent in excess air and 500 to $510^{\circ}C$ in control temperature. 6. The efficiency of coil heal exchanger increased with a decrease in feed rate of rice hull. When the rice hull feed rates were 1.1, 1.7 and 2.3 kg/h, the efficiencies of coil heat exchanger were about 34, 30 and 25 percent and heat transfer rates were 5.7, 7.6 and 8.8 MJ/h, respectively. When the flat plate heat exchanger was used in addition to the coil heat exchanger, the efficiency of the heat exchanger system increased to 48 percent.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1997.06c
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• pp.141-149
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• 1997

Structural characteristic of a rice polisher of small size was analyzed to improve its performance and to utilize such data in developing a rice polisher of large size. Spraying characteristic of nozzles which were used for rice polishing was evaluated by a machine vision system. Internal pressure of the polishing chamber was also measured according to outlet resistance, water spraying, and roller shaft speed. In addition, the performance of the polisher was analyzed based on whiteness and broken ratio according to operating conditions.

• Journal of the Korean Society of Food Culture
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• v.15 no.1
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• pp.1-8
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• 2000

This study was to investigate the effects of concentration of malt extract in Sikhye manufacture on saccharification time, shapes of saccharified rice(the cooked rice) and sensory evaluation score of Sikhye. The optimum concentration of malt extract to reduce saccharification time and to keep desirable shapes of saccharified rice was 4 times (rice 24g, malt 28g and D.W. 240ml) as suitable as base composition formula(rice 6g, malt 7g and D.W. 240ml). The shapes of saccharified rice were influenced by the concentration of malt extract, the saccharification time and the shapes of steamed rice before saccharification. A good taste(softness) of Sikhye rice and the desirable shapes of saccharified rice were more suitable in the case of a small amount of unsaccharified starch than in the case of finishing saccharification. The optimum saccharification time to keep the desirable shapes of saccharified rice was 240min and also was desirable between 210 and 270min. To keep a good taste(softness) and the desirable shapes of saccharified rice, and to reduce the manufacturing time, it is desirable to in mass production of Sikhye add 3 times more water after making Sikhye in the ratio of rice 24g, malt 28g and water 240ml. In this case the whole amount will become 4 times as much as the original one.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.287-287
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• 2017

The objective of this study was to evaluate difference of quality properties of between fresh cooked rice and re-heated cooked rice after retrogradation. Nine rice varieties raised by NICS were compared the properties of physicochemical, texture, sensory evaluation, toyo glossiness value, pasting properties. Among nine rice cultivars, the changes of weight and length-width ratio of after soaking as well as cooking showed how water absorbed in each rice granule. The amount of water absorption after soaking was highest in Wolback (semi-waxy), Hiami and lowest in Samgwang, Seonpum, Ilpum. After cooking, the amount of water absorption was high in Dasan 1 and Andabyeo, however low in Ilpum. In the length-width ratio after soaking, Wolback (semi-waxy cultivar) and Anda (indica cultivar) increase their volume relatively as their shape are while others increased more in length than width. Among cooked rice, the highest value of length-width ratio shows in Anda, Dasan1, Hiami and Seonpum, the Wolbak was similar to that of non-glutinous rice. After cooking, the others stored at $10^{\circ}C$ for 16 hours for retrogradation (imitated at convenience store). Then re-heated using by microwave. Pasting properties were considerably affected by storage temperature and periods of rice. The setback showed in the following order: Wolback (-92.25 RVU, the lowest retrogradation) < Seonpum (-35.20) < Chindle (-22.08) < Jungsanggold (-21.98). Toyo glossiness value of cooked rice showed in the following order: Chindle (82.40) > Samgwang (79.43) > Hiami (79.23). Sensory evaluation of re-heated rice of Jungsanggold, Samgwang, and Chindle were 78.97, 78.36, and 77.35, respectively. Hardness, elasticity, and toughness of re-heated rice ware increased compared to cooked rice, whereas cohesiveness was decreased. Hardness and elasticity is higher in Seonpum, Dasan1 and Hiami, toughness is higher in Jungsanggold, Samgwang and Wolbak. Cohesiveness of Jungsanggold and wolbak showed higher than others.

• Journal of Biosystems Engineering
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• v.36 no.4
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• pp.267-272
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• 2011

The latent heat of vaporization in rough rice, brown rice, white rice and rice hull was calculated by Clausius-Clapeyron equation, which does not require complex constraints as in Othmer method. Equilibrium relative humidity and ratio of the latent heat of vaporization with ln$P_{\upsilon}$ and ln$P_S$ were estimated with moisture contents ranging from 10% (d.b.) to 36% (d.b.) with 2% (d.b.) increment and temperatures ranging from $10^{\circ}C$ to $50^{\circ}C$ with $2.5^{\circ}C$ increment. An empirical equation for calculating the latent heat of vaporization in rice was developed as a function of moisture content and temperature. The equation agreed well with the calculated results. The ratio for latent heat of vaporization were the greatest for white rice while they were similar among rough rice, brown rice and rice hull.