• Computers and Concrete
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• v.25 no.5
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• pp.433-445
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• 2020

A method is proposed in this paper to estimate the workability of self-compacting concrete (SCC) in different mixing conditions with different mixers and mixing volumes by recording the mixing process based on deep learning (DL). The SCC mixing videos were transformed into a series of image sequences to fit the DL model to predict the SF and VF values of SCC, with four groups in total and approximately thirty thousand image sequence samples. The workability of three groups SCC whose mixing conditions were learned by the DL model, was estimated. One additionally collected group of the SCC whose mixing condition was not learned, was also predicted. The results indicate that whether the SCC mixing condition is included in the training set and learned by the model, the trained model can estimate SCC with different workability effectively at the same time. Our goal to estimate SCC workability in different mixing conditions is achieved.

• Journal of computational fluids engineering
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• v.20 no.1
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• pp.84-91
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• 2015

SMART adopts, very unique facility, an FMHA to enhance the thermal and flow mixing capability in abnormal conditions of some steam generators or reactor coolant pumps. The FMHA is important for enhancing thermal mixing of the core inlet flow during a transient and even during accidents, and thus it is essential that the thermal mixing characteristics of flow of the FMHA be understood. Investigations for the mixing characteristics of the FMHA had been performed by using experimental and CFD methods in KAERI. In this study, the temperature distribution at the core inlet region is investigated for several abnormal conditions of steam generators using the commercial code, FLUENT 12. Simulations are carried out with two kinds of FMHA shapes, different mesh resolutions, turbulence models, and steam generator conditions. The CFD results show that the temperature deviation at the core inlet reduces greatly for all turbulence models and steam generator conditions tested here, and the effect of mesh refinement on the temperature distribution at the core inlet is negligible. Even though the uniformity of FMHA outlet hole flow increases the thermal mixing, the temperature deviation at the core inlet is within an acceptable range. We numerically confirmed that the FMHA applied in SMART has an excellent mixing capability and all simulation cases tested here satisfies the design requirement for FMHA thermal mixing capability.

• Nuclear Engineering and Technology
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• v.29 no.3
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• pp.186-195
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• 1997

When asymmetric thermal-hydraulic conditions occur between cold legs, the core inlet temperature will be nonuniform if the coolant is not mixed perfectly in the lower plenum. These uneven core inlet conditions may induce the change in core power distribution. Thus realistic prediction of thermal mixing is important in such abnormal conditions. In this study, reactor internals, which are scaled down as to conserve the flow area ratio, are set up in the model of KORI Unit 1 with the scaling factor of 1/710 by volume and coolant temperatures are measured beneath the lower core plate. Based on experimental results, the ability of COMMIX-1B code to simulate the coolant mixing phenomena in the lower plenum is estimated. The results show that complete mixing never occurs in any conditions and the mixing pattern is characterized according to the plant type.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.809-814
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• 2009

Deep mixing method has been used for ground improvement and foundation system for embankment, port and harbor foundations, retaining wall, and liquefaction mitigations. It has attractive benefits because it is not only improved strength of soft ground but superior for prevention of settlement. However, the quality controls of improved mass affect to the efficiency of the deep mixing method is not properly established. These effects vary depending upon the construction environments and conditions of agitation in consideration of an agitator. The strength and shape of the improved column are not unique and these are affected by mechanical properties of agitators. In this study, in order to investigate the efficiency of deep mixing method for ground improvement on a soft clay ground, experimental studies are performed considering mechanical properties of agitator; the location of exit-hole of admixtures, an angle of mixing wing and a speed of revolution. The experiments are conducted with the simulated apparatus for deep mixing plant that reduced the scale in 1:8 of the real plant. According to the results, the diameter and shape of improved column mass vary depending on the mechanical properties and operating conditions of agitator. Its quality is better when the exit-hole of admixtures is located in the mixing wing, when an angle of mixing wing is large, and when the speed of revolution is rapid.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.535-544
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• 2021

When baking, the proper blending or mixing of materials will affect the quality of the product. The mixing strength is important when establishing the optimal conditions for batter, and control of the mixing condition is accordingly an important factor. This study investigated the effects of the mixing speed and time on the quality characteristics of a gluten-free type of rice batter. The batter samples manufactured for this purpose are as follows: control (+) (wheat flour), control (-) (rice flour), T1 (1,800 rpm, 1 min), T2 (1,800 rpm, 2 min), T3 (1,800 rpm, 3 min), T4 (3,600 rpm, 1 min), T5 (3,600 rpm, 2 min), T6 (3,600 rpm, 3 min). In this study, rice flour was used in the T1 to T6 samples. The pH of the batter tended to be higher when the mixing speed was slower and the time was shorter depending on the ultra-high mixing conditions. The moisture content of T3 was highest, and there was no difference according to the ultra-high speed conditions. The specific volumes of the ultra-high mixing treatments were higher than those of the control samples. The relationship between the specific volume, hardness and springiness of rice bread according to the mixing speed and time was weak. Therefore, it is considered that the application of ultra-high speeds when manufacturing gluten-free batter can have a positive effect on improving the production efficiency by reducing the processing time.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.466-475
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• 2017

Coolant mixing under natural circulation flow regime constitutes a key parameter that may play a role in the course of an accidental transient in a nuclear pressurized water reactor. This issue has motivated some experimental investigations carried out within the OECD/NEA PKL projects. The aim was to assess the coolant mixing phenomenon in the reactor pressure vessel downcomer and the core lower plenum under several asymmetric steady and unsteady flow conditions, and to provide experimental data for code validations. Former studies addressed the mixing phenomenon using, on the one hand, one-dimensional computational approaches with cross flows that are not fully validated under transient conditions and, on the other hand, expensive computational fluid dynamic tools that are not always justified for large-scale macroscopic phenomena. In the current framework, an unsteady coolant mixing experiment carried out in the Rossendorf coolant mixing test facility is simulated using the three-dimensional porous media capabilities of the thermal-hydraulic system CATHARE code. The current study allows highlighting the current capabilities of these codes and their suitability for reproducing the main phenomena occurring during asymmetric transient natural circulation mixing conditions.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.537-542
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• 2014

This study was carried out to optimize cholesterol removal in whole egg using crosslinked ${\beta}$-cyclodextrin (${\beta}$-CD) and to recycle the ${\beta}$-CD. Various factors for optimizing conditions were concentration of the ${\beta}$-CD, mixing temperature, mixing time, mixing speed and centrifugal speed. In the result of this study, the optimum conditions of cholesterol removal were 25% crosslinked ${\beta}$-CD, $40^{\circ}C$ mixing temperature, 30 min mixing time, 1,200 rpm mixing speed and $2,810{\times}g$ centrifugal speed. The recycling was repeated five times. The cholesterol removal was 92.76% when treated with the optimum conditions. After determining the optimum conditions, the recyclable yields of the crosslinked ${\beta}$-CD ranged from 86.66% to 87.60% in the recycling and the percentage of cholesterol removal was over 80% until third recycling. However, the cholesterol removal efficiency was decreased when the number of repeated recycling was increased. Based on the result of this study, it was concluded that the crosslinked ${\beta}$-CD was efficient for cholesterol removal in whole egg, and recycling is possible for only limited repeating times due to the interaction of the ${\beta}$-CD and egg protein.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.99-104
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• 2007

The deep soil mixing, on ground modification technique, has been used for many diverse applications including building and bridge foundations, port and harbor foundations, retaining structures, liquefaction mitigation, temporary support of excavation and water control. This method has the basic objective of finding the most efficient and economical method for mixing cement with soil to secure settlements through improvement of stability on soft ground. In this research, the experiments were conducted on a laboratory scale with the various test conditions of mixing method; the angle of mixing wing, mixing speed. Strength and shapes of improved soil of these test conditions of deep mixing method were analysed. From the study, it was found that the mixing conditions affect remarkably to the strength and shapes of improved soils.

• Communications of the Korean Mathematical Society
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• v.16 no.1
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• pp.125-135
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• 2001

In this article we investigate the dependence between components of the random vector which is given as an asymptotic limit of an array of random vectors with interlaced mixing conditions. We discuss the cross covariance of the limiting vector process and give a stronger condition to have a central limit theorem for an array of random vectors with mixing conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.7 s.262
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• pp.732-738
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• 2007

Effects of melt-mixing conditions on fracture properties of hydroxyapatite filled bioabsorbable poly(L-lactic acid)(HA/PLLA) composites was investigated by measuring the firacture toughness value of HA/PLLA composites prepared under different mixing time and rotor speed. The fracture surface morphology was also examined by profile measurement and scanning electron microscopies. It was found that the fracture toughness of HA/PLLA composites decreases due to decrease of ductile deformation of PLLA matrix and debonding of interfaces with increase of the rotor speed and mixing time. Effect of mixing process on neat PLLA was also assessed, and it was found that the fracture toughness of PLLA decreases due to disappearance of multiple craze formation and increase of defects. Such thermal and shear-stress degradation were found to be the primary mechanisms of the degradation of HA/PLLA composites during melt-mixing process.