• The Journal of Engineering Geology
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• v.29 no.3
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• pp.211-222
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• 2019

This study evaluates the yield load and allowable bearing capacity of ground in compressive loading tests to confirm the effect of CPR foundation reinforcement. The average compressive strength of the injection materials was higher than the planned compressive strength. Standard penetration tests for each stratum showed that foundation reinforcement improved the average N values, thereby increasing the bearing capacity of the ground. Compressive loading tests on two CPR piles revealed that the total and net settlement due to the maximum load exceed that permissible for the CPR pile diameter. The yield load and allowable bearing capacity calculated by the settlement criterion and the load-settlement curves varied greatly with the method applied. Therefore, it seems to be necessary to determine the optimum value through comprehensive analysis after applying various yield load calculation methods.

• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.214-224
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• 1976

This research was attempted as one of studies on the strength of mortar added admixtures at different curing temperatures. Variations of curing temperature to. test compressive strength, tensil strength and bending strength were $20^{\circ}C$, $30^{\circ}C$ and $35^{\circ}C$ and these results were summarized as follow : In strength of mortar added briquette ash, the compressive strength was increased: 1.58 percent, the tensile strength 0.96 percent, and the bending strength 1.26 percent compared with standard strength, by increasing one degree of celsius temperature. Also in strength of mortar added fly ash, the compressive strength increased on the average 1.3 percent, the tensile strength 0.99 percent, and the bending strength 1.18 percent at the above conditions. In case of using fly ash as admixture, maximum compressive strengths was attained at the level of 25 percent of fly ash, maximum tensile strength at the level of 20 percent of fly ash, and maximum bending strength at the level of 20 percent of fly ash. In case of using briquette ash, maximum compressive strength was attained maximum strength at 20 percent of the admixture, maximum tensile strength at the level of 15 to 20 percent of admixture and maximum bending strength at the level of 20 percent of admixture. Although addition of briquette ash was less effective in increasing the strength compared with the addition of fly ash, briquette ash might be used as one of admixtures because the control of curing temperature might affect in getting the required practical strength.

• KCI Concrete Journal
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• v.13 no.1
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• pp.19-25
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• 2001

Based on the orthotropic hypoelasticity formulation, a constitutive material model of concrete taking account of triaxial stress state is presented. In this model, the ultimate strength surface of concrete in triaxial stress space is described by the Hsieh's four-parameter surface. On the other hand, the different ultimate strength surface of concrete in strain space is proposed in order to account for increasing ductility in high confinement pressure. Compressive ascending and descending behavior of concrete is considered. Concrete cracking behavior is considered as a smeared crack model, and after cracking, the tensile strain-softening behavior and the shear mechanism of cracked concrete are considered. The proposed constitutive model of concrete is compared with some results obtained from tests under the states of uniaxial, biaxial, and triaxial stresses. In triaxial compressive tests, the peak compressive stress from the predicted results agrees well with the experimental results, and ductility response under high confining pressure matches well the experimental result. The reinforcing bars embedded in concrete are considered as an isoparametric line element which could be easily incorporated into the isoparametric solid element of concrete, and the average stress - average strain relationship of the bar embedded in concrete is considered. From numerical examples for a reinforced concrete simple beam and a structural beam type member, the stress state of concrete in the vicinity of talc critical region is investigated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.117-118
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• 2022

High-strength concrete is used for building durability on the coast. It is common to order and produce the concrete from several ready mixed concrete companies. The concrete in Busan was also commissioned by 12 ready mixed concrete companies. The compressive strength and salt diffusion coefficient were measured. The average value and deviation were analyzed.

• Smart Structures and Systems
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• v.14 no.5
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• pp.785-809
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• 2014

In this paper, an Adaptive nerou-based inference system (ANFIS) is being used for the prediction of shear strength of high strength concrete (HSC) beams without stirrups. The input parameters comprise of tensile reinforcement ratio, concrete compressive strength and shear span to depth ratio. Additionally, 122 experimental datasets were extracted from the literature review on the HSC beams with some comparable cross sectional dimensions and loading conditions. A comparative analysis has been carried out on the predicted shear strength of HSC beams without stirrups via the ANFIS method with those from the CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94 codes of design. The shear strength prediction with ANFIS is discovered to be superior to CEB-FIP Model Code (1990), AASHTO LRFD 1994 and CSA A23.3 - 94. The predictions obtained from the ANFIS are harmonious with the test results not accounting for the shear span to depth ratio, tensile reinforcement ratio and concrete compressive strength; the data of the average, variance, correlation coefficient and coefficient of variation (CV) of the ratio between the shear strength predicted using the ANFIS method and the real shear strength are 0.995, 0.014, 0.969 and 11.97%, respectively. Taking a look at the CV index, the shear strength prediction shows better in nonlinear iterations such as the ANFIS for shear strength prediction of HSC beams without stirrups.

• Journal of Conservation Science
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• v.30 no.3
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• pp.287-298
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• 2014

This study investigates the material properties of the traditional bricks used in the royal tomb of King Muryeong. Compressive strengths, thermal conductivities, absorptance and the rate of residual moisture are measured by non-destructive experiments. Compressive strength of the traditional bricks is estimated by using the ultrasonic wave velocity and the absorptance. Based on the experimental results, the predicted compressive strengths using the ultrasonic wave velocity are unsuitable for the traditional bricks due to the rough surface and thickness variation of the specimens. The strengths using the absorptance are more suitable than those using the velocity because the predicted average strengths (28.69 MPa ~ 33.19 MPa) are close to building materials like normal strength concrete. In addition, the methods using the absorptance are not influenced by surface and thickness conditions of the specimens. The average thermal conductivities of the bricks measured by using Mathis TCi are close to those of soils (1.58 W/mK). The absorptance and the rate of residual moisture of the bricks are 1.6 % ~ 15 %, 0 % ~ 0.7 %, respectively.

• Steel and Composite Structures
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• v.21 no.4
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• pp.921-947
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• 2016

Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.109-116
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• 2008

In order to test the adhesive capacity of carbon fiber sheet, a static loading method for bending-behavior-type beam specimens, cut in half was developed and test was conducted with compressive strength of concrete set as the test parameter. The tests were performed to prescribe adhesive shear strength based upon the result of shear failure as well as verification of testing method. First of all, the test method proved to be reliable in determining the adhesive shear strength. The test result also exhibited two types of variations in adhesive shear strength. Among two types of variations, average and minimum values for adhesive shear strength, relatively stable results, 3.41MPa and 2.11MPa, respectively. Particularity in the adhesive shear strength with respect to compressive shear strength was not found.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1057-1062
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• 2000

The purpose of this study is to practice the method which can estimate 28-days strength of concrete in advance. This method is made for reliant quality control. Based on existing experiment, concrete that flyash added and normal concrete are placed into wall structure, and it is examined the difference between experiment use concrete and field use concrete. The result of this study are as follows : 1) Core test specimen have 10% lower strength to standard curing specimen. 2) At 28-days accelerated strength by microwave, average 35% in normal concrete, average 23% in flyash added concrete. 3) At coefficient of determination between compressive strength and accelerated strength, 0.84 in normal concrete core, 0.86 in standard curing normal concrete, 0.86 in flyash added concrete, 0.90 in standard curing flyash added concrete.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.652-656
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• 2005

The samples were prepared with hydroxyapatite(HAp) powder and Polycaboxylate (P.C/HAp=10, 15, 20, 25, 30, 35 $wt\%$). The hydroxyapatite green body with Polycaboxylate were obtained by compaction and drying at room temperature for 3hrs. The higher mechanical properties were observed in HAp sample with $35 wt\%$ Polycaboxylate. The average compressive ana bending strength in HAp with $35 wt\%$ Polycaboxylate are $302 kgf/cm^2$ and $213 kgf/cm^2$ respectively. This strength is higher compare to that of the cortical bone.