• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.52-57
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• 2018

The pile construction method is changing from the pile driving operation to the injected precast pile method. It is to prevent environmental damage and to minimize complaints caused by noise. Therefore, economic alternatives optimized for the injected precast pile method are required. In this study, the enhanced spun reinforced concrete piles manufactured by high strength materials were proposed. Experimental tests were conducted to evaluate their structural safety and nonlinear finite element analysis was performed to improve the reliability of experimental results. The experimental results and the analytical results were in good agreement with each other and the proposed enhanced spun reinforced concrete pile has better performance than that required by the design. However, the performance of the joint using the existing method used in the PHC pile was considered to be insufficient.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.228-233
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• 1992

The objective of this report is to investigate the effect of factors on the centrifugal compaction of concrete piles with design of experiments. The analysis of sludge and measurement of compressive strength of specimens compacted by centrifugal of vibration were performed. As a result, there were some effective factors like unit content of cement, high and middle centrifugal force and time. It was considered that the process of centrifugal compaction of concrete piles could be optimized with these results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.467-474
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• 2004

A large-eddy simulation is performed for turbulent flow in a concentric annulus with the inner wall rotation at Re$\sub$Dh/=8900 for three rotation rates N=0.2145, 0.429 and 0.858. Main emphasis is placed on the inner wall rotation effect on near-wall turbulent structures. Near-wall turbulent structures close to the inner wall are scrutinized by computing the lower-order statistics. The anisotropy invariant map for the Reynolds stress tensor and the invariant function are illustrated to reveal the altered anisotropy in turbulent structure. Probability density functions of the splat/anti-splat process are explored to develop a sufficiently complete picture of the contributions of the flow events to turbulent production. The present numerical results show that the altered turbulent structures may be attributed to the centrifugal instability, which leads to the augmentation of sweep and ejection events.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.503-506
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• 2002

BSCCO 2212 HTS was fabricated by CFP(centrifugal forming process). The powder was initially ground in the mixing ratio of 2:2::1:2 with 10% of SrSO$_4$. The temperature increased up to 1035$^{\circ}C$ and 1200$^{\circ}C$ for melting. The melt was poured into the preheated and rotating copper mould from 200 to 600$^{\circ}C$. The specimen was not broken by thermal impact when the melting temperature was over 1050$^{\circ}C$ and copper mould was preheated over 400$^{\circ}C$ for 30min. A tube type of specimen was annealed at 840$^{\circ}C$ or 860$^{\circ}C$ in oxygen atmosphere for 24hours. Typical microstructure was analyzed in terms of CFP parameters by XRD, SEM, and EDS and also superconducting characteristics were compared.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.211-215
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• 2000

Bi-2212 HTS tube was fabricated by CFP(Centrifugal Forming Process). Slury was prepared in the mixing ratio of 8:2 between powder and binder and ball-milled for 24 hrs. Slurry was initially charged into the rotating mold with 300${\sim}$450 rpm and heated at the temperature ranges of 840${\sim}$860$^{\circ}$C for partial melting to finally obtain a uniformly textured tube shape. It was observed the plate-like grains with more than 20 ${\mu}$m were well oriented along the rotating axis and the measured T$_c$ was around 67K. In this paper we will discuss and analyze the tube characteristics depending on many different processing parameters such as, powder composition, binder mixing ratio between powder and binder, motor speed, heating temperature and etc.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.801-804
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• 2000

High-temperature superconductor of Bi-2212 system was fabricated by CFP(Centrifugal Forming Process). To make a uniform specimen slurry was prepared in the ratio of 7:3(powder : binder) and ball milled for 24 hours. Milled slurry was charged into a rotating mold with 450 rpm and dried at room temperature. Then the specimen was performed binder burn-out at 35$0^{\circ}C$ and heated for partial melting to 86$0^{\circ}C$. XRD analysis of most specimens were shown 2212 phase and observed a local plate shped microstructure with a well aligned c-axis direction from SEM images. Measured T$_{c}$(Critical temperature) was about 64 K.K.

• Journal of Powder Materials
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• v.19 no.4
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• pp.304-309
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• 2012

The purpose of our study was to develop the fabrication method of porous diatomite ceramics with a porosity gradient by centrifugal molding. The processing variables of centrifugal molding were derived from Stoke's law of sedimentation, which were the radius of the particles, the acceleration due to centrifugal molding and the dynamic viscosity of the slurry. And these could be controlled by ball-milling conditions, centrifugal conditions, and the addition of methyl cellulose, respectively. The effects of processing conditions on the gradient pore structure of diatomite were investigated by particle size analysis, scanning electron microscope, and mercury porosimeter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.189-192
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• 2000

High-temperature superconductor of Bi-2212 system was fabricated by CFP(centrifugal forming process). To make a uniform specimen slurry was prepared in the ratio of 7:3(powder:binder) and ball milled for 24 hours. Milled slurry was charged into a rotating mold with 450 rpm and dried at room temperature. Then the specimen was performed binder burn-out at 35$0^{\circ}C$ and heated for partial melting to 86$0^{\circ}C$. XRD analysis of most specimens were shown 2212 phase and observed a local plate shaped microstructure with a well aligned c-axis direction from SEM images. T$_{c}$(Critical temperature) of Bi-2212 was 64K.K.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.37-40
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• 2008

Recently, Construction Business, is changing very quickly, exceedingly needs to slim down the construction expensive by reducing material costs and the term of works. The term of formwork takes 25% of the term of works and costs 15% to 20% of the cost of construction. Hereupon, the purpose of this study is to investigate the Axial Strength of Centrifugall Formed Shell PC Columns that can reduce the term of formwork, the costs of material, the difficulty of throwing away the waste. Shell PC Column is loaded stirrups and manufactured at factory, so it has good points like construction's quality control and part's precision. However, it needs to be tested for checking bonded ability because it is set up at core and coverd with concrete. therefore this study is necessary three type of columns, which are a RC column, different type of two compressive strength core concrete columns and a Shell PC Column. By three columns, this study compare with and analysis three columns's bonded and Compressive Behavior abilities.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.222-227
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• 2018

Recently, due to the deterioration and various natural disasters caused by the passage of concrete pole for 20~30 years or more, damage and destruction of the poles have increased the demand for maintenance. In this paper, 10 flexural strength test specimens were fabricated by using crack self - healing concrete of Fly ash, GGBS, CA, etc. The compressive strength of the concrete with slag was found to be excellent, but the concrete with fly ash was slightly below the reference strength. In addition, the crack loadings of the specimens satisfied the criteria of KS F 4304. In the case of the load-deflection and strain relations, the behavior of the fly ash specimens was similar, but in the specimens containing the blast furnace slag, The results showed that a large amount of strain occurred.