• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.34-39
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• 2001

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is finding a way to prevent concrete void and concrete suitable for top down, through V-metering for top down column and concrete experiment.

• Journal of the Korea Institute of Building Construction
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• v.1 no.2
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• pp.191-195
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• 2001

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is finding a way to prevent concrete void and concrete suitable for top down , through V-metering for top down column and concrete experiment. To minimize the void of reverse placement joint, It is more effect to use the sheath method then direct method in concrete placement.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1107-1112
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• 2000

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is finding a way to prevent concrete void and concrete suitable for top down, through V-metering for top down column and concrete experiment.

• Journal of the Korean Society of Visualization
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• v.15 no.1
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• pp.41-46
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• 2017

Control of mixing and transport processes are the key areas that can be benefited by understanding the hydrodynamics in gas-liquid two-phase flows. In particular, the enhanced bubble-induced liquid-phase mixing is known to be a function of void fraction distribution, gas phase velocity and so on. To further our insight on the characteristics of the liquid-phase mixing induced by the bubbles, in the present study, we experimentally investigate the mixing performance of a rectangular bubble column while changing the void fraction from 0.006 to 0.075%. A shadowgraphy technique is used to measure the gas-phase properties such as void fraction and size/velocity of bubbles. On the other hand, we use dye visualization with low diffusive buoyant dye to directly measure the level of mixing. Finally, we confirm that the time taken for full mixing scales with the inverse of volume void fraction.

• The Journal of the Acoustical Society of Korea
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• v.10 no.2
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• pp.36-43
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• 1991

Acoustic backscattering from a buble column in water was studied theoretically and experimentally. For theoretical analysis a general scattering theory was used by assuming the bubble column to be lumped element scatterer which can be characterized by its shape, void fraction and dimensions. When the void fraction is less than 1% and the incident frequency is higher than individual bubble resonance frequencies, the experimental results show that the acoustic backscattering from a bubble column depends mainly on the void fraction rather than the individual bubble sizes. It was also theoretically and experimentally observed that the acoustic backscattering levels were increased and their peaks moved to the lower frequency regin by raising the void fraction of bubble column.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1101-1106
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• 2000

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is to find a solution of removing void and air, way to exhaust air in top down column. through specimen concrete placing experiment.

• Journal of Industrial Technology
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• v.16
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• pp.175-179
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• 1996

This research is the experimental and numerical study of investigating the characteristics of consolidation due to selfweight of soft marine clay. Column tests and centrifuge tests were carried out to selfweight of soft marine clay. Column tests and centrifuge tests were carried out to simulate the selfweight consolidations in field. Tests were conducted with changing drain boundary conditions and initial void ratios corresponding to four and five times of liquid limits. The RI meter was used to measure void ratio during consolidation of sample in column tests. Test results were analyzed by using the Terzaghi's infinitesimal strain theory and the finite strain theory.

• Journal of the Korea Institute of Building Construction
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• v.5 no.1 s.15
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• pp.105-109
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• 2005

Classified with concrete as placing ways - direct ways, sheath way - and placing directing flange direction, web direction - is analyzed section and strength of hardened concrete. The results of this study is belows the more fluid of concrete, the more useful to top-down method. To minimize the voids of the reverse placement joints, It is more effect to use the sheath method than direct method in concrete placement. If the joint face is a plane, it is impossible to extract the air bubbles which caused voids, so we should consider about this, and decide to select which type of joints.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.1
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• pp.23-29
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• 2007

The measurement of physical properties such as apparent density and void fraction of tobacco materials, which is so bulky, is a main theme with regard to tobacco process, quality control, cigarette combustion and smoke generation. Except Solution Impregnation Method, there was no alternative method for measuring those properties in the porous material so far. However, experimental processes of that method are so complicated as to cost much time and labor, the main solution such as mercury to apply to the method is usually very hazard. Therefore, we had developed a new method to determine them easily in our other paper by the mathematical equations derived from the Ergun equation for the purpose of it, and then already evaluated our method through applying some basic data from Muramatsu et at. (1979) with regard to our developed equations. Then, we found our method best fit to experimental one (Oh et al., 2001). In this study we tried to establish our method to conveniently determine those physical properties. Especially, we have focused on the development the easy way to measure surface area and the volume of single shred in a tobacco column. As a result of that, we found that the computer image analyzer was best fit for it. Then, we have finally determined apparent density and void fraction for our domestic tobacco shred.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.367-374
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• 2010

The transfer slab system is a structural system that transfers the loads from the upper shear wall structure to the lower columns. This is a costly system due to a very thick slab, and the relatively high cost can be mitigated by introducing voids in the slab. However, this system of flat plate containing voids is vulnerable to brittle failure caused by punching shear in vicinity of slab-column connection. Thus, the punching shear capacity of the void system is very important. However, the current code doesn't provide a clear design provision for the strength of slabs with a void section. In this study, experimental study was conducted to investigate the punching shear strength of the void slab system. The shear strength of the specimens was predicted by current code and previous researches. In result, the punching shear strength of the void system is determined as the least value calculated at critical section located a distance d/2 from the face of the column and the center of the void section using the effective area at critical section.