• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.252-258
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• 1999

As an effective means to convey crushed materials from seabed to on board ship and to raise hazardous or abrasive liquids air-lift pump provides a reliable mechanism due to its simple config-uration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newto-nian liquids. it is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates and furthermore attachment of downcomer gives little effects on riser performance the conveyed liquid flow rate increases with larger submergence rate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.350-352
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• 1988

This study was carried out to know the influence of turbidity of submerged water on photosynthetic rate of rice plant after water submerging treatment. Rice plants were transplanted in the pot at maximum tillering stage and they were sumberged for 3days at meiotic stage, 20days after transplanting, in the plastic container which had the clear and turbid water temperature adjusted around 24 to $25^{\circ}C$. Photosynthetic rate at 6 hours recovery after submergence was 41.5 to 54.2% compared to the control, but in the case of cultivar 'Nagdongbyeo', it was rapidly increased by 97.3 to 104.6% in the clear water and by 68.6 to 77.5% in the turbid water at 2 to 4 days recovery after submergence. Photosynthetic rates per plants at 6 hours to 4 days recovery after submergence were 128.3 to 245.5 $C_2$ mg.hr.$^{-1}$, in 'Samgamgbyeo' and 71.1 to 162.4 $CO_2$, mgㆍhr.$^{-1}$ in 'Nagdongbyeo' Photosynthetic rate to respiration ratio of rice plant recovery after submergence was lower compared to control plant and it was lower in 'Nagdongbyeo' than that in 'Samgangbyeo'.ngbyeo' than that in 'Samgangbyeo'.gangbyeo'.pos;.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.227-227
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• 2017

This study was conducted to analyze the reduction of quality and ripening rate of rice due to submergence during ripening stage and identify the physiological cause. Korean japonica type rice cultivars, Nampyeong was used in the experiment. The following 7, 14 day after heading, they were then moved into submergence treatment facility and we conducted the tests under three different submergence conditions - T1(clear water and overhead submergence), T2(Muddy water and exposure of Flag leaf end ), T3(Muddy water and overhead submergence), and the treatment lasted for 4days. The decrease of ripening rate was most severe in T3 treatment at 7days after heading, and the decrease of head rice ratio was most severe in T3 treatment at 14days after heading. Meanwhile the starch synthesis was inhibited, as the supply of assimilation products was inhibited in grain during the submergence treatment. And in stem, sucrose content was increased because the soluble carbohydrates accumulated before heading were decomposed. These changes may be due to the consumption of respiratory substrate in anaerobic conditions and the inhibition of the production of photosynthetic products by light interception. In order to see what kind of reaction occurs at the molecular level, we examined the degree of RNA expression in grain, stem and leaf. First, the expression of rna associated with starch synthesis in grain was decreased in all submergence treatment. and especially Ospul(DBE) was more decreased in 14days after heading treatment than 7days after heading treatment. This difference can explain the result that the decrease of head rice ratio was more severe at 14days after heading. And in stem, the expression of rna associated with the supply of assimilation products was decreased in submergence treatment. Finally in leaf, the expression of rna(ADH, ALDH) associated with anaerobic respiration was increased, while the expression of rna associated with photosynthesis was decreased. These results of physiological analysis can used to develop the cultivation technique and to offer the information for breeding the cultivars with tolerant characteristics to submergence stress during ripening stage in rice.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.3
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• pp.1-8
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• 2002

Clayey paddy soils should be mixed with other good coarse soils to be used as a material for the lining, or, embankment. However, it has been difficult to separate soil particles from each other because of the internal cohesion in the soil gradation(separation) characteristics of the fine soil were investigated by various laboratory tests including the slaking durability test. Degradation rate of the soil were dependent upon the clay content and the initial water content before the submergence. The amount of degradations decreased as initial water content increased with exponential functions. The dried specimens separated into the particles after 24 hours of the submergence and specimens which water contents were less than 10% also separated into the particles after 2, or 3 days of the submergence. Compaction curves and the unconfined strength were not varied before and after the submergence. However, unconfined strength decreased as water content increased.

• Magazine of the Korean Society of Agricultural Engineers
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• v.25 no.2
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• pp.35-41
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• 1983

This research is mainly to deal with the effects of submergence treatment on the grain yields of two rice plants, local variety, "Akibare" and Tongil line variety, "Milyang 23". The results obtained are summarized as follows. 1. According to the rice products of each plot the grain yield index was smallest in the plot treated at the early heading stage. The index of the next order became smaller in order of late flowering stage, late reduction division stage, milk ripe stage and dough ripe stage etc. The submerged stage at which the damages were smallest was tillering stage. Under the condition of two thirds or one third submerged depth of plant height, few differences in the grain yield index between Milyang 23 and Akibare was found, but except rooting stage, the damages of milyang 23 by whole submergence during growing period were mostly greater than those of Akibare. Especially the grain yield index of early heading stage at which the damages by whole submergence was most serious showed 45 percentage for one day submergence, 31 percentage for 3 days and 0.7 percentage for 7 days in Akibare plots, and 26.7% percentage for one day submergence, 7.9 percentage for 3 days and none for 7 days in Milyang 23 plots. 2. All the factors such as submerged stage, submerged depth and submerged period in this experimental test were highly recognized significance. The factors of the submerged depth and duration influenced on greater damages than the others. According to the difference in grain yield between plots, the larger the submerged depth and duration were, the larger the significant difference appeared. And between the treated levels at other submerged stages except both early tillering stage and most active tillering stage, the significance in the differences in grain yield was recognized, while only the submergence at early heading stage showed the most serious damages. 3. The decreased rate of grain yield for one day submergence at early heading stage indicated that in case of whole submergence of plant height it was 73 percentage in Milyang 23 plot and 55 percentage in Akibare plot, and in the event of two thirds and one third submergences of it, 20 percentage and 10 percentage in both Mulyang 23 and Akibare plots respectively. Therefore, the current criteria for planning project that restricted allowable submergence duration of more than 30cm submerged depth to 24 hours, should be amended not to exceed the submerged depth of 60cm when the duration of more than allowable submerged depth of 30cm will be limited to 24 hours, or within the limits of 12 hour submerged duration for locai variety and of less than 12 hour duration for Tong-illine variety as long as possible in case that submerged depth will be allowed to more than 60cm depth.ore than 60cm depth.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.837-845
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• 2013

An airlift pump can be used to pump liquids and sediments within itself, which cannot easily be pumped up by a conventional method, by using the airlift effect. This characteristic of the airlift pump can be exploited in a DCFC (Direct Carbon Fuel Cell) so that molten fuel with high temperature may be carried or transported. The basic characteristics of airlift are investigated. A simple system is constructed, where the reservoir is filled with water, a tube is inserted, and air is supplied from the bottom of the tube. Then, water is lifted and its flow rate is measured. Bubble patterns in the tube are observed in a range of air flow rates with the parameters of the tube diameter and submergence ratio, leading to four distinct regimes. The pumping performance is predicted, and the correlation between the supplied gas flow rate and the induced flow rate of water is found.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.14-21
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• 1999

As an effective means to convey crushed materials from seabed to onboard ship and to raise hazardous or abrasive liquids, air-lift pump provides a reliable mechanism due to its simple configuration and easy-to-operate principle. The present study is focused on investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newtonian liquids. It is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates. The comparison between riser performance of the conveyed liquid flow rate calculated by the computer program and measured data with large scale air lift pump system constructed in 200 meter depth vertical tank reveals similar distribution.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.239-244
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• 2006

As an effective means to convey crushed materials from seabed to onboard ship, air-lift pump provides a reliable mechanism due to its simple configuration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance through analysis program based on the gas-liquid two-phase flow in circular pipes. It is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates.

• Journal of Forest and Environmental Science
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• v.23 no.2
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• pp.93-100
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• 2007

This study was carried out to select the utilizable vegetations for the stabilization of slopes and river banks, landscape creation and water quality cleansing in dams, lakes and streams. In this study, 4 species were investigated for their survival and growth characteristics in the complete and partly flooding conditions with various flooding periods. The results are as followings; Acorus calamus var. angustatus showed the highest flooding tolerance based on survival rate and growth condition. Equisetum hyemale, Acorus gramineus and Salix gracilistyla followed after Acorus calamus var. angustatus in the order of flooding tolerance. Particularly, A. calamus var. angustatus and E. hyemale showed higher survival rate and grew well even when they were completely submerged in the water up to 120 days. As they were partially submerged longer, they grew better. This ascertained that they had strong flooding tolerance. When A. gramineus were completely submerged in the water, their growth was disturbed but they did not die in the complete submergence up to 120 days. A. gramineus had a small growth disturbance and showed the highest vitality of leaves among the species. Though S. gracilistyla showed somewhat low growth rate in the complete water submergence and died in 90 days, it also can grow back to normal with some changes of water level.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.238-243
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• 1981

An empirical formula for the mass flow rate in natural convection flume above a spherical heated body which is submerged in a finite fluid contained in a tank was determined. The ratio of depth of submergence to diameter of the sphere for which the sphere sensed as infinite medium was found to be bigger than 7. A dimensionless heat transfer correlation for the natural convection from a sphere was determined for Gr.Prq etween 7x10$\^$7/ and 2x10$\^$8/ also.