• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.4 s.19
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• pp.29-36
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• 2005

In this study, relations among unconfined compressive strength, strain at maximum strength and depth were compared with each other. Test specimen is marine clay originated from the place near Ga-duck island in Busan city. In addition, influence of impure material contained in specimen and that of total core recovery(TCR) on unconfined compressive strength and degree of disturbance were investigated. As a result of tests, unconfined compressive strength decreases as strain corresponding to maximum strength increases. Also, the deeper the sampling depth and the bigger the TCR, the unconfined compressive strength increases. Especially, as the TCR increases, the unconfined compressive strength Increases and quality of specimen is enhanced.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.81-90
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• 2011

Domestic usage of high strength steel for pile has been limited to steel with yield strength (YS) of 490 MPa. However, design and construction cases abroad show beneficial usage of steel pipe with YS ranging in 500~700 MPa. In this study, YS 590 MPa steel pipe has been tested for driven pile foundation in Songdo area. Pile dynamic analysis (PDA) was carried out for 18 piles of which 16 piles have been reviewed for comparison of the PDA test results with those of GRLWeap analysis using SPT N value. Back analysis of PDA analysis was also carried out to narrow the deviation of standard SPT N value used in GRLWeap analysis. A regression equation is suggested for the shaft and toe resistance according to SPT N values for future GRLWeap analysis that can be used in the designing stage at Songdo area.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.465-474
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• 2014

This is a comparative study that shows the overall environmental impacts from concrete structures when different compressive strength of concrete applied to structural systems having the same reference flow with different durability. A total of 24 MPa, 40 MPa and 60 MPa cases is analyzed to define the characteristic using end-point perspective LCA methodology including the stages of production, construction, maintenance and disposal. As results, global warming, non-renewable energy and respiratory inorganics problems are the major issues for assessing environmental impacts of concrete products.

• Journal of Korean Society of Steel Construction
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• v.14 no.2
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• pp.385-394
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• 2002

Currently, high strength steel is not used for steel bridges in Korea, except for the SM570 high strength steel in very isolated cases. The study aimed to promote the active adaptation of high strength steel for long-span steel bridges. Thus, the fatigue behavior of SM570 and POSTEN80 high strength steel was investigated. For the experimental study, the butt welded joints samples were manufactured. Likewise, regular amplitude tensile fatigue tests were conducted. Test results, e.g., location of fatigue cracks and their propagation were compared with the findings of other researchers. After analyzing the effects of fatigue strength, e.g., static tensile strength and plate thickness of base metal, basic data for fatigue design criteria of SM570 and POSTEN80 high strength steel were presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.84-92
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• 2014

The purpose of study is to analyze mechanism with early high portland cement and hardening accelerator. As the result, it was concluded that hardening accelerator makes accelerates appearance of $Ca(OH)_2$ through experiment using TG-DTA when it hydrates with cement. On the result of compressive strength, as increasing the amount of hardening accelerator used, early compressive strength was improved. Also, as a result of hydration heat, hardening accelerator accelerates hydration of $C_3S$ that is cement's component. On the result of XRD's analyzation, hydration product for each age could be check and it was shown that as increasing the amount of hardening accelerator used, peak point of hydration product was recorded high. As the result of SEM, appearance of C-S-H was shown as the amount of $Ca(OH)_2$'s appearance and each age according to additive contents of hardening accelerator. Therefore hardening accelerator used on this study is effective on getting early compressive strength.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.527-536
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• 2017

The aim of this study was to develop an understanding of the mediating effect of job search efficacy on perceived career development support and job support intensity of university students of physical education major. Data were collected by a total of 223 junior and senior students who are undergraduate majoring in physical education in Seoul, Chungnam, and Gyeongsang Provinvces. For the study, the reliability and validity test of the questionnaire and correlation analysis were conducted by using SPSS 20.0 program, and Structural Equation Model(SEM) using AMOS 20.0 program was conducted to analyze the data. The results were as follows. First, career development support perceived by university students of physical education majors had a statistically significant effect on job search efficacy, whereas it had no significant effect on job search intensity. Second, job search efficacy of the students had a statistically significant effect on job search intensity. Lastly, it was found that job search efficacy totally mediated the relationship between perceived career development support and job search intensity.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.139-146
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• 2008

The characteristics of the biaxial flexural tensile strength of concretes was compared to that of the uniaxial strength. The uniaxial and biaxial strengths in this study were obtained from the classical modulus of rupture test and the biaxial flexural test recently developed by Zi and Oh and Zi et al., respectively. Three different sizes were considered to investigate the effect of the size of aggregates. To estimate the stochastic aspect of the strength, 32 specimens were used for each test. The average biaxial flexural fracture strength was about 20% greater than the uniaxial test. At the same time, the coefficient of variation for the biaxial test was 18% greater than the uniaxial test. This means that the probability of the biaxial cracking can be greater than the uniaxial cracking.

• Journal of the Korean Data and Information Science Society
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• v.20 no.3
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• pp.563-575
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• 2009

This research has found logical data directly influencing forming consideration set and attitude and attitude strength under the choosing situation based on memory-base proposed by Priester et. al (2004). We've examined the possibility of model extension through physical salient strength according to the location of product display as an external stimulate factor and attitude and attitude strength, consideration set and role on variable choice. Especially, this research practically proposed the method measuring directly the attitude on behavior instead of seeing the intension of behavior or behavior by measuring the behavior itself based on existing experiment methods and applied logistics regression analysis. In conclusion, this research confirmed the possibility of generalization of this model by verifying appropriateness through logical background and actual analysis based on stimulus-base proposed model characters as an integrated model relation between attitude in stimulus-based relation and decision-making.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.131-138
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• 2017

In this study, the expansion and compressive strength tests of emergency restoration material were carried out to restore cavity causing ground subsidence. The expansion and compressive strength characteristics according to component ratio of main material - hardener and mix proportion of blowing agent - accelerator were analyzed based on the test results. As a result of the relationship of curing time - expansion ratio analyses, it confirmed that expansion ratio decreased with reduced curing time regardless of mix proportion of blowing agent - accelerator in main material, if component ratio of hardener increased. This means that component ratio of the main material - hardener had greatly affected the expansion ratio. The compressive strength characteristics of emergency restoration material confirmed that strength was affected by mix proportion of blowing agent - accelerator. Therefore, it is necessary to apply reasonable component ratio and mix proportion to consider the required injection time, expansion ratio and strength of restoration material, when emergency restoration in ground cavity is required.

• Land and Housing Review
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• v.4 no.3
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• pp.295-301
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• 2013

In this study, cases of domestic tall residential buildings were investigated for the structural types, numbers of stories, total heights, type of lateral load resisting systems, and zoning of concrete strength. Based on these investigation data, the structural planning pattern of tall residential building was analyzed. SRC structure is main structural types of tall residential building at the initial stage of domestic tall residential building, but RC structure is substituted for main structural types since 2005. Retaining wall system is positioned at the core part of structural plan as a lateral load resisting system. Concrete strength zoning of vertical members like columns are divided by vertical heights of lower parts, middle parts, and upper parts. Basic data of structural planning of 40stories and 60 stories residential buildings was proposed based on case investigation.