• Journal of Welding and Joining
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• v.14 no.4
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• pp.71-78
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• 1996

The effect of chemical composition on mechanical properry and corrosion resistance of austenitic stainless steel was investigated. The main results obtained were as follows : 1. There was a linear relationship between the tensile strength of stainless steel and the $Cr_{eq}/Ni_{eq}$. The larger the $Cr_{eq}/Ni_{eq}$ was the higher the tensile strength of stainless steel. 2. There was a good correlationship between $Cr_{eq}/Ni_{eq}$ and intergranular, gerneral corrsion rate. 3. Intergranular corrosion rate decreased linearly with increasing Cr content. 4. General corrosion rate decreased linearly with increasing Ni content. 5. Logarithm corrosion rate of intergranular and general corrosion has a linear relationship with all of the factor of $Cr_{eq}/Ni_{eq}$, Cr and Ni content.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.546-554
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• 2023

The cyclical behavior of Alloy 617 was examined at 25 ℃ and high temperatures of 800, 850, 900, and 950 ℃ in air to obtain its fatigue life curves. The specimens tested at 25, 800, and 850 ℃ cyclically hardened, whereas those tested above 900 ℃ cyclically softened from the first cycle, that is, their fatigue life was reduced at high temperatures owing to loss of strength. Parameters of the typical Coffin-Manson-Basquin relationship were determined for each test temperature. Interestingly, no significant difference in fatigue life was observed for the specimens tested in the range of 800-950 ℃. Owing to the similarity in fatigue life, we determined fatigue strength and fatigue ductility exponents that could be applied for this temperature range. The parameters obtained were close to the universal slopes, although the fatigue ductility exponent was slightly different. The proposed fatigue life curves were compared with those presented in ASME code.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.309-317
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• 2002

The mechanical characteristics of Light-Weighted Foam Soil(LWFS) are investigated in this research. LWFS is composed of the dredged soil from offshore, cement and foam to reduce the unit-weight and increase compressive strength. For this purpose, the unconfined compression tests and triaxial compression tests are carried out on the prepared specimens of LWFS with various conditions such as initial water contents, cement contents, curing conditions and confining stresses. The test results of LWFS indicated that the stress-strain relationship and the compressive strength are strongly influenced by the cement contents rather than the intial water contents of the dredged soils. On the other hand, the stress-strain relationship from triaxial compression test has shown strain-softening behavior regardless of curing conditions. The stress-strain behavior for the various confining stress exhibited remarkable change at the boundary where the confining stress approached to the unconfined compression strength of LWFS. In order to obtain the ground improvement of the compressive strength above 200kPa, the required LWFS mixing ratio is found to be 100%~160% of the initial water contents of dredged soil and 6.6% of cement contents.

• Journal of the Korea Institute of Building Construction
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• v.7 no.4
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• pp.125-132
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• 2007

The use of Self-Leveling material is increasing recently. This paper assesses the quality of surface layer of concrete floor when Self-Leveling material is defective. The paper shows how to predict the defect of SL material before construction begins. The relationship between the quality of surface layer of concrete floor and the defect of SL material was determined and the quality of surface layer of concrete floor was then estimated. The relations between the quality of surface layer and the defect of SL material were determine considering surface strength, moisture, and consistency of surface layer. Absorbing amount was used as the indicator of consistency and the absorbing amount of test material was measured. Then the relations between the test material and surface strength were determined. Generally concrete floor with greater consistency has greater surface strength, however in this study, we hound that high impact concrete floor could have lower surface strength as the consistency gets bigger. The relations between the level of defect occurred in SL material and the quality of surface layer were examined and we clarified that the surface layer with lower consistency gets higher possibility to occur exfoliation in early stage, one or two weeks after constructing SL material. When the consistency is sufficient, the occurring situation of defect depends upon the moisture of surface layer. Little amount of moisture gets higher possibility not to occur the defect. As the amount increases, fissure generates and early exfoliation may occur. In addition, the level of fissure is highly related with the surface strength.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2234-2241
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• 2015

This study has been undertaken to develop a relationship between the shear strength coefficients and the cone index. The theoretic mathematical equations for the relationship were rigorously investigated, and then a Artificial Neural Network(ANN) analysis was adapted to enhance the reliability of the investigation. The theoretical investigation involved various assumptions resulting in the significant error involvement of geotechnical behaviors of ground. Therefore, a model using the ANN has been learned to enhance the prediction of the cone index form the shear strength parameters. Site investigation reports from various construction fields were used for ANN model learning. The results of the study show that the model predicts the cone index from the shear strength parameters of soils very well. The further study that is undertaking has a potential promise of the generalized prediction technique for the cone index from the soil parameters.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.369-376
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• 2012

In this study, to reduce the hydration heat velocity (HHV) of high-strength mass concrete at early ages, phase change materials (PCM) that could absorb hydration heat were applied, and the changes in autogenous shrinkage were investigated, as well as the relationship between the hydration temperature and autogenous shrinkage. The acceleration of the cement hydration process by the PCM leads to an early setting and a higher development of the compressive strength and elastic modulus of concrete at very early ages. The function of PCM could be worked below the original melting point due to the eutectic effect, while the hydration temperature and HHV of high-strength mass concrete can be decreased through the use of the PCM. A close relationship was found between the hydration temperature and autogenous shrinkage: the higher the HHV, the greater the ultimate autogenous shrinkage.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.365-376
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• 2011

The current Concrete Structural Design Code (2007) prescribe the equivalent rectangular stress block of the ACI 318 Building Code as concrete compressive stress distribution for design of concrete structures. The rectangular stress block may be enough for flexural strength calculation, but realistic stress-strain relationship is required for performance verification at selected limit state in performance-based design. Moreover, the ACI rectangular stress block provides non-conservative flexural strength for high strength concrete columns. Therefore a new stress distribution model is required for development of performance-based design code. This paper proposes a concrete compressive stress-strain distribution model for design and performance verification. The proposed model has a parabolic-rectangular shape, which is adopted by Eurocode 2 and Japanese Code (JSCE). It was developed by investigation of experimental test results conducted by the authors and other researchers. The test results cover high strength concrete as well as normal strength concrete. The stress distribution parameters of the proposed models are compared to those of the ACI 318 Building Code, Eurocode 2, Japanese Code (JSCE) and Canadian Code (CSA) as well as the test results.

• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.825-831
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• 2007

The use of high-strength aluminum alloys for ship and offshore structure generally has many benefits compared to the structural steels. These materials are used widely in a variety of fields, especially in the hull and deck of high speed craft, box-girder of bridges, deck and side plates of offshore structure. The structural weight can be reduced using these aluminum structure, which can enable high speed The characteristics of stress-strain relationship of aluminum structure are fairly different from the steel one, because of the influence of Heat Affected Zone(HAZ) by the welding processing. The HAZ of aluminum is much wider than that of steel with its high heat conductivity. In this paper, the ultimate strength characteristics of aluminum stiffened panel subjected to axial loading, such as the relationship between extent of HAZ and the behavior of buckling/ultimate strength, are investigated through the Finite Element Analysis with varying its range.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.217-223
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• 2019

The relationship between balance and ankle muscle characteristics (strength and flexibility) may be important to identify those at an increased risk of falling and to develop fall-prevention training programs. The association between ankle muscle characteristics (strength and flexibility) and balance has not previously been studied. The purpose of this study assessed the relationship between ankle muscle characteristics and balance. Sixteen healthy participants volunteered to participate in the study. Dynamic balance measured using Y-balance kit. Ankle muscle characteristics (strength and flexibility) measured using hand-held dynamometer and goniometry. The results indicated a positive correlation between ankle invertor muscle strength and Y-balance test performance. Clinicians should consider ankle muscle strength during therapeutic interventions to improve dynamic balance.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.419-425
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• 2021

This study explores effective ways to improve the happiness of the primary caregiver of disabled children based on the comprehensively identification of their influencing factors. Based on the results of a comprehensive review of the relationship between the influencing factors, this study seeks to explore directions and policy alternatives that are effective in improving the happiness of the primary caregiver of disabled children. The effects of social support, parenting stress, family strength, and happiness were examined in this study using data collected from 430 primary caregivers of disabled children in three regions of Jeollabuk-do. The main findings of the analysis are as follows: First, it was discovered that social support has a direct effect on the happiness of the primary caregiver of disabled children, as well as an indirect effect via family strength. Second, the primary caregivers of disabled children's family strength was discovered to have a partial mediating effect on the relationship between social support and happiness. Convergence suggestions were presented based on the research findings to promote social support, family strength, and feelings of happiness for primary caregivers of children with disabilities.