• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.820-825
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• 1989

Yukwa (one of most popular Korean traditional popped rice snacks) was made by four different varieties of rice, Shinsun (Japonica) and Hangang $(Japonica{\times}Indica)$ which are waxy rice and Dongjin (Japonica) and Samgang $(Japonica{\times}Indica)$ which are non waxy rice, for their quality by total expansion volume, hardness and brittleness. It was notified that hydration rate of waxy and non waxy rice for preparation of Yukwa were different by 30% and 42% in moisture content respectively soaked at $12^{\circ}C$ for 12 hours and the gelatinization temperature of their starch was $64.5-67.5^{\circ}C$ with no big difference by varieties. The quality of Yukwa was deeply related with amylose contents ranging from 18.5% of non waxy rice to 2-3% of waxy rice. Superior quality (p<0.05) was got from waxy rice. Lactic acid bacterial fermentation didn't improve the quality, and soybean and rice bran oil can be used for popping in even value.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.231-237
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• 2005

Gypsum treated to fine sandy loam increased the fornation of >2 mm aggregates in $1,550kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg1) and $3,100kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg2) to compare with control, Kc, at 60DAT, and bigger aggregates in general at 90DAT. The higher treatment of gypsum level, the <0.1 mm aggregates were less decreased as in Kbfg1, Kbfg2, and $6,200kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg3) and aggregates of 0.25->2 mm were increased with increasing level of gypsum with more effective in Kbfg2 and Kbfg3 at 120DAT. Gypsum treated to silt loam increased aggregates of 2.0-1.0 and 1.0-0.5 mm in $3,100kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Mbfg2) to compare with control (Mc), at 60DAT. Degrees of aggregation from 0.5-0.25 mm to >2 mm aggregates at 90DAT were distinctly higher. The higher treatment of gypsum level accelerated more aggregation of silt loam soil, and aggregates of 0.5-0.25 mm was most increased in Mbfg2 at 120DAT. Popped rice hulls treated to fine sandy loam increased aggregates of 2.0-1.0 mm in plots of $1,000kg\;10a^{-1}$ (Kbfhl) only to compare with control (Kc), at 60DAT, and aggregates of >2 mm and 2.0-1.0 mm Kbfh1 at 90DAT. At 120DAT, aggregation by popped rice hulls was most effective in Kbfbl pot. Popped rice hulls treated to silt loam increased in aggregates of >2 mm and 2.0-1.0 mm in $2000kg\;10a^{-1}$, Mbfb2 to compare with control, Mc, at 60DAT. Degrees of aggregation by popped rice hulls at 90DAT were higher in $1,000kg\;10a^{-1}$, Mbfh1, and Mbfh2, and at 120DAT was in $3,000kg\;10a^{-1}$, Mbfb3. Zeolite treatment with popped rice hulls, $1,500kg\;10a^{-1}$, increased in >2.0 mm aggregates in $1,000kg\;10a^{-1}$, Kbfbz1, $2,000kg\;10a^{-1}$, Kbfbz2, $3,000kg\;10a^{-1}$, Kbfhz3, and Mbfbz1, $1,000kg\;10a^{-1}$, Mbfbz2, $2,000kg\;10a^{-1}$, and $3,000kg\;10a^{-1}$, Mbthz3, to compare with control (Kc and Mc), at 60DAT. irrespective of soil texture. At 90DAT, >2.0-0.5 mm aggregates increased in Kbfhz1 of fine sandy loam. aggregates of >0.25 mm in $200kg\;10a^{-1}$ (Mbfbz1), $400kg\;10a^{-1}$ (Mbfhz2), $800kg\;10a^{-1}$ (Mbfhz3) of silt loam increased with the level of zeolite treatment. At 120DAT, the effect of zeolite treated to both soils showed the decrease of <0.1 mm aggregates. As the result, soil amendments for soil aggregation was more effective in the order of popped rice hulls+Zeolite > gypsum > popped rice hulls in fine sandy loam, and in the order of gypsum > popped rice huUs+zeolite > popped rice hulls in silt loam, respectively.

• Proceedings of the Korean Environmental Health Society Conference
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• 2002.04a
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• pp.55-56
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• 2002

Aflatoxin is a secondary fungal metabolite and is a public health hazard because it is a human carcinogenic and has many deleterious effects in men and animals. Rice is one of the better substrates for the fungus which can produce aflatoxins. This study was performed to investigate aflatoxin reduction during the cooking and processing of rice. Aflatoxin was produced by Aspergillus parasiticus ATCC 15517 on well-milled rice(Japonica type) at the level of 13.2 ppb. Cooked rice, rice cakes (baek-sol-gi, plain steamed rice bread), fermented rice (sik-hye, sweet rice beverage), and popped rice were prepared from the aflatoxin-contaminated rice. Aflatoxin content in the samples was determined by high performance liquid chromatography. The total aflatoxin level was decreased to 46.9％ in the cooked rice, 85.6％ in the rice cakes, 11.4％ in the fermented rice, and 7.6％ in the popped rice, respectively (p＜0.05). This reduction brought the level of aflatoxins down to below the Standard and Specification of Korea (10 ppb), except for the rice cakes. These results indicate that washing, steaming, fermentation, and popping of rice was helpful in reducing the aflatoxin level in the rice and the most helpful factors were high temperature & high pressure. More research is needed to understand why the preparation of rice cakes did not reduce the level of aflatoxin as much as the other cooking methods.

• Korean Journal of Medicinal Crop Science
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• v.21 no.1
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• pp.45-48
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• 2013

This study was carried out to know the substitute effect of Yacto (leaf mold compost) on popped rice hulls compost (PRHC) in Yang-jik nursery bed of Panax ginseng. PRHC was mixed with Yacto as 50:50 ratio, and 1 ~ 2% of the mixed oil cake, rice bran and urea were also added to promote decaying the mixed compost. The mixed compost made by PRHC and Yacto was showed that positive effect on the growth of ginseng seedling when it was mixed with 1% of oil cake and rice bran, and 2% of mixed oil cake. But addition to the 2% of urea in the mixture of PRHC and Yacto was not positive effect on the growth of ginseng seedling. Root yield of the mixed compost was similar to that of conventional compost by made 100% of Yacto. Therefore, the mixed compost can substitute for Yacto when PRHC and Yacto were mixed by 50:50 ratio and added 1% of oil cake and rice bran.

• Korean Journal of Food Science and Technology
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• v.22 no.3
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• pp.272-277
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• 1990

Some additives were applied to improve Yukwa(Popped rice snack) quality and process modifications were tested for cutting down soaking time and application of rice flour. Addition of soaked soybean (3%, w/w) to dough showed higher expansion rate and better physical properties with more acceptable quality by sensory evaluation of Yukwa. Baking powder, modified starch and alcoholic liquor, Mackeali(rice wine, turbid). Soju(distilled liquor) and Yakju(rice wine, clear), were no positive effect on quality of Yukwa but alcoholic liquor gave more fine texture than others. High temprature soaking $(60^{\circ}C)$ of rice for 3 hours which is near gelatinization temperature of rice starch. gave same quality of Yukwa comparing with long time soaking (12 hours) at room temperature. Extention of high temperature soaking (12 hours) did not improve the quality of Yukwa. The 100 mesh of rice flour by dry milling method was better in expansion rate and hardness than 40 and 80mesh but it was worse than ordinary wet milling. It was notified that milling method and milling mechines for Yukwa preparation should be studied in more detail.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.2
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• pp.41-50
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• 2013

We investigated influence of continuous application of gypsum(G:$CaSO_4{\cdot}2H_2O$), popped rice hulls(H) and zeolite(Z) on soil aggregation of reclaimed silt loam soils. The application rates amended to silt loam from reclaimed soils at Saemangeum of Mangyeong were varied as follows; 1550(G1), 3100(G2), 6200 (G3) gypsum kg/10a, 1000(H1), 2000(H2), 3000(H3) popped rice hulls kg/10a, and 200(HZ1), 400(HZ2), 800(HZ3) zeolite kg/10a added to 1500 popped rice hulls kg/10a, respectively. In addition, the bermuda grass was growing, and the soil aggregates were analyzed for 60, 90 and 120 days after treatments(DAT). At 60 DAT, the effect of treatment was in order of G>H${\geq}HZ$, and the 1550kg/10a(G1) was the highest as 52.48%. At 90 DAT, the effect of treatment was also in order of G>H>HZ. Those was 3.78-3.12, 2.03-3.03 and 1.79-2.57 times in compared with the control, respectively. At 120 DAT, the effect of treatment was similar continued in order of G>H>HZ. Those was 3.00-2.20, 1.06-1.64 and 0.92-1.23 times in compared with the control, respectively. In conclusion, we found that the continuous application for two year of gypsum, popped rice hulls and zeolite was excellent above the 1 year, and the effect of the treatment for soil amendments of reclaimed silt loam soil was excellent in order of G>H>HZ.

• Journal of the Korean Society of Food Culture
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• v.21 no.6
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• pp.679-684
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• 2006

In this experiment, I used three samples of oils. The oils that I used were hydrated soybean oil, pure soybean oil and regular soybean oil. The group of rice was fried in the each sample of oil that had not been used for a few seconds. Rice was used after frying at 230-235$^{\circ}C$ every four hours terms and total frying hours was 12 hours. The hydrated soybean oils was least affected in rancidity. The other two oils were more affected in rancidity than the hydrated soybean oil. However, the trans fatty acid in hydrated soybean oil was 36.5%. The diameter of the poped rice that was fried in pure soybean oil and regular soybean oil that had been used 12 for hours was reduced while the diameter of the popped rice fried in the hydrated soybean oil was not reduced. Also, the groups of rice fried in the pure and the regular soybean oil that had been used for 12 hours reduced the hardness in rice while the group that fried in the hydrated soybean oil at the 12th hour kept the hardness well. In sensory evaluation, rancidity order was found apparently in the pure soybean oil that had been used for 12 hour and in the regular soybean oil that have been used for eight hours and 12 hours. Only the hydrated soybean oil did not have distinctive rancidity order at all. The degree of the crispiness was reduced in the pure soybean oil and in the regular soybean oil at 12th hour frying. However, the hydrated soybean oil preserved the crispiness well until the end of 12 hours of frying. In overall preference test, the pure and regular soybean oil that had been used for 12 hour were not preferable. In conclusion, I found that the group fried in the hydrated soybean oil was better in every evaluation than the groups fried in the pure soybean oil and in regular soybean oil. The hydrated Soybean oil may be better to be used in food manufacturing if the trans fatty acid in the hydrated soybean oil can be reduced.

• Progress in Superconductivity and Cryogenics
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• v.12 no.3
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• pp.49-54
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• 2010

This paper presents apparent thermal conductivity of various powder at different vacuum levels for cryogenic insulation. Four kinds of powder insulator are examined by using boil-off calorimetry at pressure range from 50 Torr to 3 mTorr. The first material is perlite which is widely used in cryogenic application. Microsphere is the second one that is recently proposed as a replacement powder for liquid hydrogen storage tanks. It is a hollow sphere made of silica with the diameter in the order of 10 to $100{\mu}m$. Popped rice and polystyrene beads are also selected as candidates for powder insulation even though they are polymers. With their porous elliptic and spherical configuration and light density, they demonstrate fairly good thermal insulation performance at pressure range from 50 Torr to 3 mTorr. According to the experimental investigation in this paper, microsphere and polystyrene beads possess promising insulation characteristic as powder insulators and further study is desired.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.403-408
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• 2006

Fluvio-marine paddy soils in Korea consist of high silt content and have the hardpan located below 20~30 cm from surface soil. This properties cause poor rice rhizosphere conditions such as low permeability and porosity, high bulk density and hardness. The aims of this study was to investigate the effect of popped rice hulls compost(PRHC) on soil fertility changes in the Fluvio-marine plain paddy soils. Total nitrogen content and nitrogen mineralization rate of PRHC were 1.17 and 33.5, respectively, and its C/N ratio was 35.4. Application of PRHC increased the content of organic matter and exchangeable potassium and improved the bulk density and porosity. The content of $NH_4-N$ in soil was high in the PRHC plot until maximum tillering stage. An uptake amount of fertilized nitrogen was greater in standard fertilization plot at early growth stage, however, it was greater more in PRHC plots at the ripening period than in standard fertilization plot. Among the PRHC treated plots, uptake amount was the greatest in 50% PRHC plot during the all growth period. Nitrogen efficiencies were higher in PRHC plot during the all growth period. Rice yields in all PRHC plots were lower than in standard fertilization, however, the yield of 40% PRHC plot was similar with that of standard.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.79-86
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• 2002

Aflatoxin is a secondary fungal metabolite and is a public health hazard because it is a human carcinogenic and has many deleterious effects in men and animals. Rice is one of the better substrates far the fungus which can produce aflatoxins. This study was performed to investigate aflatoxin reduction during the cooking and processing of rice. Aflatoxin was produced by Aspergillus parasiticus ATCC 15517 on well-milled rice (Japonica type) at the level of 13.2 ppb. Cooked rice, rice cakes (baek-sol-gi, plain steamed rice bread), fermented rice (sikhye, sweet rice beverage), and popped rice were prepared from the aflatoxin-contaminated rice. Aflatoxin content in the samples was determined by high performance liquid chromatography. The total aflatoxin level was decreased to 46.9% in the cooked rice, 85.6% in the rice cakes, 11.4% in the fermented rice, and 7.6% in the popped rice, respectively (p.0.05). This reduction brought the level of aflatoxins down to below the Standard and Specification of korea (10 ppb), except for the rice cakes. These results indicate that washing, steaming, fermentation, and popping of rice was helpful in reducing the aflatoxin level in the rice and the most helpful factors were high temperature & high pressure. More research is needed to understand why the preparation of rice cakes did not reduce the level of aflatoxin as much as the other cooking methods.