• Journal of the Korea Furniture Society
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• v.12 no.2
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• pp.19-27
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• 2001

This study was carried out to investigate the mechanical properties of woods treated with 30% aqueous solution of PEG 1000. Compressive, bending and shearing strengths were slightly decreased by PEG treatment. Absorbed energy in impact bending did not show any significant differences between untreated and PEG-treated woods.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.118-125
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• 2007

To obtain design data for built-up beams used as headers in light-frame timber construction, three members of $2{\times}6$ ($38{\times}140 mm$), $2{\times}8$ ($38{\times}184 mm$), $2{\times}10$ ($38{\times}235 mm$) and $2{\times}12$ ($38{\times}286 mm$) were built up as specimens of bending tests. The bending strengths of built-up headers were obtained through bending tests of these specimens, and it was considered that span tables can be calculated for various loading conditions based on the bending strengths of built-up headers. The bending strengths of built-up headers were determined as the bending stresses at 10 mm deflection of specimens from the results of bending tests of built-up beam specimens. Span tables for built-up headers were considered to be obtained by assuming five loading conditions for headers used in exterior walls and two loading conditions for headers used in interior walls. Among these 7 loading conditions, 5 loading conditions applied to headers in exterior walls included dead loads, live loads and snow loads and 2 loading conditions applied to headers in interior walls included dead loads and live loads.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.524-530
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• 2009

In the post-beam structure, the infilled light-frame construction provides most shear strengths. Shear properties of the light-frame structure can be estimated from the shear properties of nailed connection for the sheathings, and those of nailed connections can be done from nail bending strengths. For the basic study to predict the yield strength and the slip modulus of a nailed sheathing shear wall, those of a nailed joint were examined from nail bending strengths. To estimate shear properties of a nailed connection, referenced bearing strength and bearing constant for the wood members and the experimental nail bending strengths of the helically threaded nail were applied. The yield strength using the diameter at grooves instead of shank diameter was well coincided with the experimental value, but the slip modulus was estimated much smaller. The effective factors, specific gravity for the main member, withdrawal by nail head diameter to the side member, and embedment and moment at the nail head were considered, and further examinations are needed for the precise prediction of the nailed connections.

• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.3
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• pp.92-99
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• 1982

The objective of this study was to investigate the compressive and bending strength characteristics of epoxy resin mortar, which is still in an early stage of its use and study in Korea. The results obtained are summarized as follows; 1. The compressive strengths of epoxy resin mortar after 1 day, 2 days and 3 days were gained 87%, 91% and 95%, respectively, in view of that of mortar at the age of 7 days. This result showed that the initial compressive strength within 1 day was very high. 2. The highest compressive strength of epoxy resin mortar was 914 kg/cm2 at the point of having the mixing ratio of one to two. It reached up to 3.7 times that of the normal portland cement mortar at the age of 28 days. 3. The bending strengths of epoxy resin mortar after 1 day, 2 days and 3 days came up to 88%, 93% and 97%, respectively, in comparing that of mortar at the age of 7 days. It was expressed to be simielar to the tendency of compressive strength. 4. The highest bending strength of epoxy resin mortar was 384 kg/cm2 at mixing ratio of one to two. It came up to as much as 6.5 times in comparing with that of the normal portland cement mortar at the age of 28 days. Therefore, the epoxy resin mortar would be effective for promoting the bending strength of structural members. 5. The regression equation between compressive and bending strength was obtained as follows; oo~=0.391 oc+27.54 (r=0.99) And the estimated value of bending strength was corresponded to about 44 per cent in comparing with that of the compressive strength.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.161-167
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• 2001

The overhead transmission wires operating both at warm temperature and tighten state for a long period of time in a power transmission plant are degraded by air pollution, wind, creep and slip between steel wire and aluminium conductor. The objective of this study is to investigate to investigate the characteristics of fatigue properties with tension and bending loading of a high carbon steel wire. The fatigue behaviors have been carried out by tension-tension, 4 points bending and 3 points bending loading. In the present study, a conventional fatigue strengths between 4 points bending and tension-tension fatigue were determined by Gerber, Sorderberg and Goodmans theory and we investigated S-N diagram for bending and tensile loading.

• Advances in concrete construction
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• v.6 no.2
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• pp.159-175
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• 2018

The main aim of this study is to investigate the possible effects of metakaolin on strength and durability properties of concrete. For this purpose, concrete mixtures are produced by substituting cement with metakaolin 0, 5, 10 and 20% by weight. The amount of binder for the concrete mixtures are 300 and $400kg/m^3$ with a constant water to cement ratio of 0.6. Compressive and bending strengths, freeze-thaw and high-temperature resistances, capillary coefficients and rapid chloride permeability properties were determined and compared each other. Because of all the experiments conducted, it has been found that the use of metakaolin as a pozzolanic additive in concrete have positive effects especially on compressive and bending strengths, capillary, rapid chloride permeability, freeze-thaw resistance, and high temperatures, up to $800^{\circ}C$. The results indicated that the performance of concrete can be enhanced by metakaolin. Particularly, compressive strength and durability properties have found to be improved with increasing metakaolin content which is attributed to pozzolanic activity and filler effect. Furthermore, metakaolin has relatively positive impacts under elevated temperatures and freeze-thaw effects. However, almost all the strengths of entire concrete specimens are lost at $800^{\circ}C$. Consequently, the optimum metakaolin substitution ratio can be suggested to be 20% as per this study.

• Journal of the Korean Ceramic Society
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• v.23 no.3
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• pp.67-77
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• 1986

various properties and manufacturing conditions were investigated in order to synthesize the glass-ceramics of $CaO-P_2O_5$ system for bioceramics. Compositions of easy unidirectional crystallization were between 47.5 and 50, 0mol% CaO For the glass rods prepared by pulling them to about 3 times the original rod length unidirectional crystallization was easier than original glass rods. These samples were crystallized in the axial direction at 15${\mu}{\textrm}{m}$/min in an electric furnace with a temperature gradient of about 3$0^{\circ}C$/cm at 57$0^{\circ}C$. Bending strengths of surface and unidirectionally crystallized samples were investigated with various CaO/$P_2O_5$ molar ratios. The bending strengths of unidirectionally crystallized samples were larger than those of surface -crystallized samples and the value of 47.5CaO.52.5 $P_2O_5$ was 1650kg/$cm^2$. XRD patterns showed that major phase is $\beta$-Ca(PO3) with minor phase 2CaO.$P_2O_5$ Relative crystal-linity of surface-crystallized sample was inversely propertional to the bending strenth. SEM of fracture surface of unidirectionally crystallized samples revealed an unidirectionally aligned structures.

• Structural Monitoring and Maintenance
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• v.6 no.1
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• pp.47-66
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• 2019

One method of retrofitting concrete structures is to use fiber reinforced polymers (FRP). In this research, the shear, torsional and flexural strengthening of self-compacting reinforced concrete (RC) girders are fulfilled with glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) materials. At first, for verification, the experimental results were compared with numerical modeling results obtained from ABAQUS software version 6.10. Then the reinforcing sheets were attached to concrete girders in one and two layers. Studying numerical results obtained from ABAQUS software showed that the girders stiffness decreased with the propagations of cracks in them, and then the extra stresses were tolerated by adhesive layers and GFRP and CFRP sheets, which resulted in increasing the bearing capacity of the studied girders. In fact, shear, torsion and bending strengths of the girders increased by reinforcing girders with adding GFRP and CFRP sheets. The samples including two layers of CFRP had the maximum efficiencies that were 90, 76 and 60 percent of improvement in shear, torsion and bending strengths, respectively. It is worth noting that the bearing capacity of concrete girders with adding one layer of CFRP was slightly higher than the ones having two layers of GFRP in all circumstances; therefore, despite the lower initial cost of GFRP, using CFRP can be more economical in some conditions.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.274-279
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• 2000

The overhead transmission wires operating both at warm temperature and tighten state for a long period of time in a power transmission plant are degraded by air pollution, wind, creep and slip between steel wire and aluminium conductor. The objective of this study is to investigate a high carbon steel wire. We tested for basic mechanical properties and 3 types fatigue behavior, tension-tension, 4 points bending and 3 points bending fatigues. In this study, a conventional fatigue strengths between 4 points bending and tension-tension fatigue were determined by Gerber, Sorderberg and Goodman's theory and we investigated S-N diagram for bending and tensile loading.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.223-230
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• 2009

In this study we deal with bending behaviors of a concrete filled tubular(CFT) with various diameter-thickness ratios and concrete strengths. In finite element analysis using a commercial package(LUSAS), the bonding effect between concrete and steel in CFT structures is modeled by applying a joint element for the bonding surface. In order to consider the nonlinearity of concrete and steel tubes, stress-strain curves of the concrete and steel are used for the increased stresses in a plastic domain. The numerical results obtained from the proposed method show good agreement with the experimental data from load-displacement curves of a steel tube under distributed loads. Several parametric studies are focused on structural characteristics of CFT under bending effects for different diameter-thickness ratios and concrete strengths.