• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.331-334
• /
• 2005

Three RC beams are fabricated and tested to assess the ultimate load-carrying capacity. Depending on the crackings, the flexural stiffness of the RC beams are changed. However, these variations of the flexural stiffness do not influenced on the ultimate load-carrying capacity of the tested beams. Based on the behaviors of RC beams, the validation of the current assessment codes to discussed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10a
• /
• pp.828-835
• /
• 2000

In recent years, RC structures need reinforcement due to physical and chemical deterioration, reduction of serviceability and structural capacity. For reinforcement of RC structures, steel plate attachment, area increase and composite fiber sheet attachment methods are used, but there are some problems like weight increase, workability, quality control and fire resistance capacity. This study presents the effectiveness of flexural reinforcement of RC beams using composite rods that are inserted in high strength special purposed polymer mortar.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.821-826
• /
• 1998

The design methods for the steel plate strengthened RC structures are not well established yet because the structural behavior of plated RC beams is more complex than that of regular unplated ones. The main purpose of this paper is to present the premature failure mechanism of steel plate strengthened RC beams. The analytical models of interfacial stress and normal are also proposed in this paper. The comparisons between the analytical results using the proposed theory and experimental ones relatively satisfied.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.827-832
• /
• 1998

Recently, Carbon Fiber Sheets(CFS) have been used for strengthening the deteriorated RC beams and bridge decks because of its resistant capacity of corrosion and easy repairing works. In this study, the static test tare performed on RC bridge decks strengthened with CFS. Test results show that ultimate strength of specimens strengthened with CFS is increased as 15~26% comparing to the control specimen.

• Kyungpook Mathematical Journal
• /
• v.28 no.1
• /
• pp.51-62
• /
• 1988

In this work we study properties of five identities of Bol-Moufang type (1). We establish a necessary and sufficient condition for a loop to be an RC-loop. A corollary to this is the condition for a Bol loop to be an RC-loop. Some proerties of a generalization of RC-loops are discussed. We also state the relationship between the supernucleus M(G) of a loop G and the nucleii of loops which do not have the inverse property. Finally, we give two tables of non-associative RC-loops of order 16, which are not Bol loops.

• Journal of Korean Association for Spatial Structures
• /
• v.13 no.4
• /
• pp.6-10
• /
• 2013

• Journal of Korean Society of Steel Construction
• /
• v.25 no.3
• /
• pp.243-254
• /
• 2013

Internally Confined Hollow RC(ICH RC) column consisted of concrete, transverse reinforcement, longitudinal reinforcement, and inner tube. It had good strength and ductility by core concrete was become triaxial confining state with transverse reinforcement and inner tube. There were two confining stress as external confining stress and internal confining stress in an ICH RC column. While external confining stress was researched by former researchers, internal confining stress has not researched. In this paper, confining stress of both Hollow RC column and ICH RC column was investigated using FEA program. Relation between theoretical confining stress and internal confining stress was drawn by analysis results. Modified failure condition equations of inner tube were suggested to base on failure condition equations of inner tube by former researcher. When thickness of inner tube was calculated by modified equations, it could be economic because thickness of inner tube was reduced 50% compared with former researcher equations in order to same confining stress.

• Journal of the Korea Concrete Institute
• /
• v.22 no.5
• /
• pp.719-725
• /
• 2010

The analysis and experimental program of reinforced concrete (RC) structures for resistance against such extreme loads as earthquake, blast, and impact have been carried by many researchers and designers. Under the extreme loads, a large amount of energy is suddenly exerted to the structure, hence if the structure fails to absorb the impact energy, catastrophic collapse may occur. To prevent catastrophic collapse of structures, reinforced concrete must have adeguate toughness or it needs to be strengthened. The FRP strengthening method and SFRC are studied widely in resistance of impact load because of their high energy absorption capacity. In this study, drop weight impact tests were implemented to evaluate the impact resistance of SFRC and FRP strengthened RC beam while the total steel fiber volume fractions was fixed at 0.75% carbon FRP flexural strengthened RC beams. Futhermore, to prevent the shear-plug cracks when the impact load strikes the beams, additional FRP shear strengthening method are applied. The experimental, results showed that the FRP strengthened RC SFRC beams has high resistance of shear-plug cracks and crack width and SFRC has high resistance of concrete spalling failure compared to normal RC beams. The FRP flexural and shear strengthening RC beams has weakness in the spalling failure because the impact load concentrated the concrete face which is not strengthened with FRP sheets.

• Korean Journal of Medicinal Crop Science
• /
• v.7 no.1
• /
• pp.51-57
• /
• 1999

To search for antioxidative compounds from plant resources, methanol extracts of 45 plant species were investigated using DPPH method. The highest activity was shown in the methanol extract of Acer ginnala($RC_{50}\;:\;15{\mu}g$), followed by Stewartia koreana($RC_{50}\;:\;28{\mu}g$) and Carpinus laxiflora($RC_{50}\;:\;33{\mu}g$). Two antioxidative compounds were isolated from the methanolic extract of Acer ginnala Max and identified as acertannin(2, 6-di-O-galloyl-1, 5-anhydro-D-glucitol) and gallicin (methyl-3, 4, 5-trihydroxybenzoic acid) on the basis of mass spectroscopy, $^1H-\;and\;^{13}C-NMR$ data. The DPPH free radical scavenging activities of acertannin($RC_{50}\;:\;3.5{\mu}g$) and gallicin($RC_{50}\;:\;2.8{\mu}g$) were more effective than those of BHA($RC_{50}\;:\;14{\mu}g$) and ${\alpha}-tocopherol$ ($RC_{50}\;:\;12{\mu}g$).

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.4 no.4
• /
• pp.13-18
• /
• 1967

Since all the poles of the open circuit voltage transfer function of the trigonometric, linear, passive RC circuits exist on the negative real axis of s-plane, its transient response to the unit step input is monotonic. This satisfies the necessary conditions for the applicability of Elmore's method which had been developed originally for the transient analysis of lumped circuit in computing the rise time and delay time of the trigonometric distributed RC circuits. This paper describes the computing method of rise and delay times of the trigonometric distributed RC circuit. The analysis shows that the transient response of this kind circuit depends only upon the time constant and distance angle $\theta$. As $\theta$ is increased, the rise and delay titles are increased non-linearly.