• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4253-4258
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• 2012

The investigation of the undrained strength and the important several undrained geotechnical properties was, in detail, made for highly plastic soils using the field and laboratory testing results. The plastic index, activity, water content, and effective unit weight did not show the notable relationship with both Su and normalized Su. The OCR, sensitivity, and undrained elastic modulus presented remarkable tendency with normalized Su. It could be concluded that the use of the normalized Su may lead to the reasonable results then the normalized Su needs further research.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.112-118
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• 1994

Rock seems to be the ultimate excellent reaction for engineering loads, and often it Is. But the term rock includes a variety of types and conditions of material, some of which are surely not excellent and some that are potentially dangerous. Therefore, It is necessary to research absorption properties by rock strength. In this aspect the present paper deals essentially with the absorption exhibited by some Gneiss and Shale relation to its point load Index and specific gravity. In order to verify the rock strength, point load tester and two types rock specimen were used. Experimental results show that the absorption properties are highly dependent on rock strength. (suggested)

• Physical Therapy Korea
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• v.7 no.1
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• pp.32-37
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• 2000

The purpose of this study is to determine the effects of exercise training on the strength and balance ability of the elderly. The results of this study are: 1) After 8 weeks exercise training, knee muscle strength showed a significant increment. 2) After exercise training, forward functional reach and balance index of KAT 2000 showed a significant increment. Results indicate that strengthening exercise can result in improved muscle strength and balance in the elderly. Further studies are required to show long-term effects of exercise training on the elderly.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.63-65
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• 2010

The purpose of the study was to analyze dry shrinkage of HVFAC (high volume fly ash concrete) with admixture to improve early strength. The results were as follows. In dry shrinkage of HVFAC with admixture to improve early strength, F3 had the lowest amount of dry shrinkage. The next is in order of Plain, F3-f15 and F3-f15r5. The study used index function modelfor analysis on dry shrinkage. Coefficient of determination was more than 0.97 in all mix, which made it possible to have a good estimation.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.195-200
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• 1993

This paper develops practical and realistic reliability models and methods for the evalusion of system reliability and system reliability-based rating of R.C box-girder bridge superstructures. The precise prediction of reserved carrying capacity of bridge as a system is extremely difficult expecially when the bridges are highly redundant and significantly deteriorated or damaged. This paper proposes a new approach for the evaluation of reserved system carrying capacity of bridges in terms of equivalent system-strength, which may be defined as a bridge system-strength corresponding to the system reliability of the bridge. This can be derived from an inverse process based on the concept of FOSM form of system reliability index. The strength limit state models for R.C box-girder bridges suggested in the paper are based on the basic bending and shear strength. and the system reliability problem of box-girder superstructure is formulated as parallel-series models obtained from the FMA(Failure Mode Approach) based on major failure mechanism or critical failure states of each girder. AFOSM and IST(Importance Sampling Technique) simulation algorithm is used for the reliability analysis of the proposed models.

• Particle and aerosol research
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• v.8 no.2
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• pp.75-81
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• 2012

The strength of lumped cokes can be represented by some index numbers. Although some indexes are suggested, these indexes are not enough to enlighten fracture mechanism. To find essential mechanism, a computational way, discrete element method, is applied to the uniaxial compression test for cylindrical specimen. The cylindrical specimen is a kind of lumped particle mass with parallel bonding that will be broken when the normal stress and shear stress is over a critical value. It is revealed that the primary factors for cokes fracture are parallel spring constant, parallel bond strength, bonding radius and packing ratio the parallel bond strength and radius of the parallel combination the packing density. Especially, parallel spring constant is directly related with elastic constant and yield strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.239-246
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• 2003

In the PCA Load Contour Method, the biaxial bending design coefficient of columns(${\beta}$) is based on the equivalent rectangular stress block (RSB). And coefficient of ${\beta}$ estimates the reinforcement index to be a influencing parameter on biaxial moment strength of RC columns without considering the arbitrary condition of bar arrangement. The experimental results of high strength concrete (HSC) columns subjected to combined axial load and biaxial bending moment were compared to the analysis results of RSB method. As result, the accuracy of RSB method is still acceptable for HSC columns and, as the reinforcement is placed densely in each corner of column section, the ${\beta}$ is decreased.

• Economic and Environmental Geology
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• v.23 no.4
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• pp.411-424
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• 1990

Mechanical, physical and petrographic properties of seventeen marble specimens collected from ten marble mines in Korea were investigated. Studied marbles were mainly composed of calcite, dolomite, and various amounts of serpentine, tremolite, olivine, quartz and opaque minerals. Complete and sutured textures were dominant. Compressive strength measured normal to the bedding plane is larger almost two times than that measured parallel to the bedding plane. From the results of Shore hardness test on marbles, water content was an important factor to decrease Shore hardness values. Engineering geological properties, especially, compressive strength, Young's modulus, wear resistance and water absorption could be controlled by the presence of quartz, and the type of marble texture. Water absorption-porosity, compressive strength-Young's modulus, and impact strength index-Los Angeles abrasion couples show good correlation. According to the comparative utility as commercial stone, it could be concluded that marbles from the Banglim mine, Songbo mine, Kwangdeok mine and Bongjeong mine were superior to that of other studied marbles.

• Structural Engineering and Mechanics
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• v.76 no.5
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• pp.591-598
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• 2020

Ultrasonic waves provide a non-destructive and sensitive way to monitor the concrete hydration. However, limited works are reported to monitor the evolution of the mechanical parameter at early ages. In this study, modified piezoelectric aggregates are embedded inside a concrete beam to excite and receive primary waves. A hydration index, namely, the variation of ultrasonic waveform (VUW) is developed to characterize the variation of the transmitted waves during the hydration process. The recorded hydration indices are compared with the compressive strength measured by destructive test at different ages. The results show that the VUW is closer to the compressive strength than the other two traditional hydration indices, ultrasonic velocity and wave packet energy. The proposed VUW provides a simple and accurate way to monitor the concrete hydration at early ages.

• Geomechanics and Engineering
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• v.28 no.1
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• pp.35-48
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• 2022

The effect of discrete polypropylene fibre reinforcement on shear strength parameters, tensile properties and isotropic index of stabilized compacted residual subgrade was investigated. Composites of compacted subgrade were developed from polypropylene fibre dosage of 0%, 1%, 2.5% and 4% and 3% cement binder. Saturated compacted soil benefited from incremental fibre dosage, the mobilized friction coefficient increased to a maximum at 2.5% fibre dosage from 0.41 to 0.58 and the contribution due to further increase in fibre dosage was marginal. Binder stabilization increased the degree of isotropy for unreinforced soil at lower fibre dosage of 1% and then decreased with higher fibre dosage. Saturation of 3% binder stabilized soil decreased the soil friction angle and the degree of isotropy for both unstabilized and binder stabilized soil increased with fibre dosage. The maximum tensile stress of 3% binder stabilized fibre reinforced residual soil was 3-fold that of 3% binder stabilized unreinforced soil. The difference in computed and measured maximum tensile and tangential stress decreased with increase in fibre dosage and degree of stabilization and polypropylene fibre reinforced soil met local and international criteria for road construction subgrade.