• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.306-316
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• 2017

The purpose of this study was to evaluate the effects of exposure to various children's drinks on the color stability of anterior primary teeth and different esthetic restorative materials clinically used in pediatric dentistry. Exfoliated maxillary primary central incisors that had been unaffected by caries were chosen as control group. Maxillary primary central incisor-shaped specimens made of strip crown and Nu-smile zirconia crowns were chosen as test groups. Polished strip resin crowns were additionally prepared to compare with unpolished strip resin crown. Each specimen and teeth were divided into 4 groups in which the test samples (n=5 each) were immersed in 4 different drinks (distilled water, cola, grape juice, jelly juice) for 6 days. In all 4 drink groups, all specimens generally showed increasing ${\Delta}E^*$ value (color difference) with time. Polished resin strip crown had higher ${\Delta}E^*$ value than the unpolished in cola, grape juice and jelly juice groups. ${\Delta}E^*$ value of zirconia crown in cola, grape juice and jelly juice groups were significantly different (p < 0.05). In conclusion, dietary control of children's drinks is required for preventing discoloration of restorative materials.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.9
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• pp.1215-1221
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• 2009

The purpose of this work was to improve the quality of Jeungpyun made with rice sourdough, which was prepared using a mixed culture of Saccharomyces cerevisiae (S. cerevisiae) and Leuconostoc mesenteroides (L. mesenteroides) strains, and to also develop a new process for Jeungpyun preparation using the rice sourdough. The Jeungpyun was manufactured through proofing for 3 hr at $30^{\circ}C$ and steaming steps after mixing the ingredients, including pre-fermented rice sourdough, rice powder and water. After proofing, the expansion ratio of the Jeungpyun dough ranged from 109 to 135% and the pH was decreased to pH 3.80$\sim$4.09. The volumes of the Jeungpyun samples prepared with rice sourdough were 18$\sim$45% greater than that of the control. In particular, the Jeungpyun made with rice sourdough containing 10% brown rice (CM-10) had a significantly greater volume (266 mL). Also the rice sourdough Jeungpyun samples had well developed dense porous structures compared to the control. According to sensory evaluations, the sample prepared with rice sourdough containing 10% brown rice was preferred. Finally, the physical quality (texture properties) and microbiological shelf-life of the Jeungpyun was improved by using the rice sourdough.

• Journal of Bio-Environment Control
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• v.9 no.1
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• pp.47-59
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• 2000

In order to investigate the physical and chemical properties of artificial culture media, the specimens were substituted with 5~20％ clay, 10~30％(w) quick lime, 5~l5％(w) burnt plaster and 10％(w) sawdust. Fly ash-clay bodies were sintered at 1,050~1,20$0^{\circ}C$ and then their properties were determined. It was found that 90FA10JC(fly ash ＋clay(90：10, ％(w)) specimen sintered at 1,15$0^{\circ}C$ for 10 min. had good physical and chemical properties. When this composition was supplement with 10％(w) sawdust, bulk density water absorption, apparent porosity, compressive strength and pH after 240 hrs curing time were 1.14, 54.4％, 39.5％, 54 kgf.cm$^{-2}$ and 7.1 respectively. The physical properties of fly ash-quick lime-burnt plaster system specimens were superior to FAJC systems. However, this composition we not suitable as a artificial culture media because of its high pH. In this study, it was shown that 90FA10JC10SD(90FA10JC ＋10％(w) sawdust) system exhibited the best physical properties.

• Journal of Bio-Environment Control
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• v.12 no.4
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• pp.221-227
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• 2003

The objective of this research was to determine the effect of seed priming on membrane integrity during poriming and germination. Among the five chemicals, $KNO_3$at 150 mL gave the shortest $T_{50}$ (days required to reach 50% of the final germination percentage). Compared to unprimed, the seeds primed with 150 mL $KNO_3$ at 20$^{\circ}C$ for 4 days had reduced $T_{50}$ values when germinated at 15$^{\circ}C$. These results indicated that seed priming is an effective way for rapid and synchronized germination, especially at low temperature. Changes in conductivity of priming solutions during the 4-days period of priming were highly dependent upon the priming agents. Conductivity of the $KNO_3$ and $K_3PO_4$ solution slowly declined during the first 3 hours ad then increased Amount of amino acids, sugars and proteins exuded from seeds into $KNO_3$ solution were less than those into distilled water and $K_3PO_4$. All the results suggested that the $KNO_3$ priming play a positive role in regulating the permeability of cell membranes.

• Journal of Bio-Environment Control
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• v.9 no.1
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• pp.40-46
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• 2000

This study was conducted to investigate the comparison of storability on film sources and storage temperature and determine the proper condition for fresh Japanese mint in U storage. The fresh weight in storage was maintained well more than 40$\mu$m ceramic film(CE 40) thickness. The carbon dioxide, ethylene, and acetaldehyde contents in 80$\mu$m ceramic film(CE 80) was higher than those in CE 40. Those were not different among the storage temperatures, rather, those in 3$^{\circ}C$ and 1$^{\circ}C$ storage were higher than those in 1$0^{\circ}C$. The chlorophyll contents loss was promoted by above 5％ water loss and 0.5ppm ethylene contents, but mote than 4％ carbon dioxide contents restrained from degrading chiorophyll. The storage period in 3$^{\circ}C$ was 30 days that was twice longer than those in other storage temperatures. The visual quality was higher in CE 40 at 3$^{\circ}C$, and this plot was lowest in ion leakage that was shown the degree of chilling injury. It was concluded that storage temperature of at 3$^{\circ}C$ and packaged ceramic 40$\mu$m film to increase storability of Japanese mint would be favorable.

• Journal of Bio-Environment Control
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• v.25 no.1
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• pp.49-56
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• 2016

This study was conducted to develop the disinfection system using electric shock for recycled nutrient solution in recycling soilless culture. Stainless steel (SUS 316) was found as the most appropriate electrode material for electrical disinfection system from the view of high electrical conductivity, low electric resistance, and low price. There were no changes in nutritional elements when the electric shock passed through the nutrient solution by stainless steel electrode. The amount of electric current increased with width than thickness of the electrode. The farther the distance between the electrodes was increased the time to reach out the aimed amount of current. The electric shock was applied to Ralstonia solanacearum and Fusarium oxysporum as representative bacteria and also fungi. Any of those pathogens were killed with the percentage of higher than 97% in the condition of 15VDC or 24VDC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.189-196
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• 2012

The heavy moderator acts as the ultimate heat-sink in an operating CANDU reactor. HUKINS has been developed to investigate moderator flow patterns. HUKINS consists of a 38.4-mm-thick cylindrical shell with a 0.95 m inner diameter and 88 sus-tubes that produce a total heat of 10 kW. A chemical visualization method was selected to estimate the occurrence of typical moderator flow patterns. Momentum-dominated flow, mixed flow, and buoyancy-dominated flow are detected under conditions of a heat load of 7.7 kW and input mass flow rates of 4, 7, and 11 L/min. The experimental results are similar to the results of a CFD simulation that consisted of approximately 1.9 million grids and was conducted using the k-${\varepsilon}$ turbulence model. Therefore, both the present experiments and simulations using HUKINS, a 1/8-scale model, represent all three important flow patterns expected in the real CANDU6 reference reactor. Thus, it has been demonstrated that HUKINS could be useful in the study of CANDU6 moderator circulation.

• Journal of Bio-Environment Control
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• v.15 no.1
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• pp.69-77
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• 2006

The experiment was conducted to investigate the nutrition absorption pattern in the growth stage and develope the optimal nutrient solution hydroponically grown the cherry tomato 'Koko' in closed substrate culture system with the nutrient solution of National Horticultural Research Station in Japan into 1/2S, 1S, and 2S. When plant was grown in 1/2S, the growth and yield were high and the pH and EC in the root zone were stable. Suitable composition of nutrient solution for cherry tomato was $NO_3-N\;6.8,\;PO_4-P\;2.7,\;K 3.2,\;Ca\;3.6\;and\;Mg\;1.1\;me\;L^{-1}$ in the early growth stage, $NO_3-N\;7.3,\;PO_4-P\;2.2,\;K\;3.7,\;Ca\;3.6;and\;Mg\;1.1\;me\;L^{-1}$ in the late growth stage by calculating a rate of nutrient and water uptake. To estimate the suitability for the nutrient solution in a development of cherry tomato developed by Wongkwang university in Korea (WU), plant was grown in perlite substrate supplied with different solution and strengths(S) by research station for greenhouse vegetable and floriculture in the Netherlands (Proefstation voor tuinbouw onder glas th Mssldwijk; PTG) of 1/2S, 1S, and 2S, respectively. The growth was good at the PTG and WU 2S in the early stage and the PTG of 1S and WU of 1S and 2S in the late stage. The highest yield of cherry tomato obtained in the WU of 2S. pH and EC in root zone of WU of 2S were stable during the early and late growth stage. Therefore when cherry tomato plant was grown in WU of 2S of EC $1.6{\sim}2.0\;dS\;m^{-1}$in the nutrient solution, not only stable growth and yield but also fertilizer reduction can be obtained than that of PTG.

• Journal of Bio-Environment Control
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• v.16 no.1
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• pp.7-12
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• 2007

This study was conducted to clarify the effects of the different concentration of the nutrient solution on the early growth and the nutritional contents of hydroponically grown Aster koraiensis, Hemerocallis fulva and Plantago asiatica at 70 days after transplanting in perlite culture. Balanced nutrient solution formulated by Japanese Horticultural Experiment Station was used as the standard concentration of the nutrient solution. Overall plant growth of Aster koraiensis and Hemerocallis fulva such as plant height, stem diameter, number of loaves, fresh and dry shoot and root weight were significantly increased in 1.5 times concentration of nutrient solution. Shoot and root fresh and dry weight of hydroponically grown Plantago asiatica were significantly increased in the higher concentration of the nutrient solution, however, number of loaves and root length were significantly increased in the standard and the lower concentration of the nutrient solution. The highest contents of calcium, magnesium and sodium in plants were shown in Aster koraienxis which were grown in the 1.5 times concentration of nutrient solution, and Hemerocallis fulva and Plantago asiatica in 0.25 times of that. The contents of potassium in Aster koraiensis and Hemerocallis fulva were significantly increased when the plants were grown in the 0.5 times concentration of the nutrient solution, and that in Plantago asiatica in the 1.5 times concentration of the nutrient solution. The contents of phosphoric acid in plants as affected by the different species of Namul and the different concentration of the nutrient solution were not significant.

• Journal of Bio-Environment Control
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• v.16 no.1
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• pp.62-66
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• 2007

This study was carried out to develop the stable plug seedling production for hydroponics of spinaches by various nursery media, plug tray size and seed number per plug tray cell. When plant grown in various nursery media, the seeding stand rate was shown in order of granular rockwool with good water retention, granular rockwool>granular rockwool mixed with pearlite>cocopeat>pearlite>poly urethane foame. Thus, poly urethane foame indicated the lower seedling stand rate. There was no difference in growth of the seedlings md the seeding stand rate by the plug tray size, and no significant difference in the plant height and the number of leaves among the seed number per plug tray cell. But, leaf area of plant in 2 grains seeding per cell was $113.0cm^2$, was wider in compared with 5 grains seeding of which leaf area was $88.0cm^2$. Accordingly, the leaf area per plant decreased as more and more the number of seeds per plug tray cell increased. The fresh weight of a plant per plug tray cell was the heaviest with 12.5g in the 2 grains, and the total fresh weight of plants per cell was 33.9g in 4 grains seeding, thus it tended to was bigger compared with other treatments. Consequently, given that the number of seeds per cell was decreased, the fresh weight of a plant increased. On the other hand, the total fresh weight per cell showed a tendency to be reducing as more and more the number of seeds per plug tray cell decreased. The yield in the 4 grains seeding was increased by 46% as $14,910kg{\cdot}ha^{-1}$ in compared with the yield in 2 grains seeding as $10,200kg{\cdot}ha^{-1}$.