• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.593-596
• /
• 1999

Steel fibers are added to concrete to improve energy absorption, impact resistance and apparent ductility, and to provide crack resistance and crack control. This study is to investigate the toughness index and post-crack equivalent tensile strength of steel fiber reinforced concrete properties on the load-deflection behaviors of the steel fiber reinforced concrete beam model specimens.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.04a
• /
• pp.69-74
• /
• 1991

This paper reviewed various methods of evaluating the toughness of fiber reinforced concrete materials by means of toughness indices and discussed the use of various multiples of first-crack deflection or first-crack secant compliance to define toughness indices. And a new method what is called effective toughness used to evaluate the toughness of steel fiber reinforced concrete. The proposed method determinded from the area below the load-deflection curve until deflection at the loading point becoms 1/150 of the span devided by the ligament area.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.6
• /
• pp.3760-3768
• /
• 2015

This study was to examine the correlation of Personality and EEG. Personality test and EEG of the 40 team leader of a business enterprise were carried out at the same time and the correlation of test results were analyzed. Personality test was done by Big 5 and brain waves were measured by 2-Channel EEG System at Fp1 and Fp2. The analysis showed a positive correlation between the Big 5 agreeableness and SRQ(Self Regulation Quotient) relaxation status which is related with alpha rhythm, and showed a negative correlation between the Big 5 openness and SRQ concentration status which is related with low_beta rhythm. It means that the personality is closely correlated with human brain cortex activation and can be checked by brainwave analysis.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.6 s.58
• /
• pp.166-175
• /
• 2009

An experimental study was carried out to estimate the flexural performance of steel fiberreinforced self-compacting concrete. Seven slabs with three different steel fiber-reinforced concretes were prepared to make beam specimens. After proper curing period, each slab was cut to five beams with a diamond saw. The beam specimen was tested with displacement control method to obtain load-deflection curve. As the results, the self-compacting concrete beam showed higher flexural strength, ductility and toughness index compared to the normal concrete beam. This means that steel fiber-reinforced self-compacting concrete can be used more widely in the field of architecture and civil engineering because of its self-compactability and good mechanical properties.

• Journal of Korean Home Economics Education Association
• /
• v.27 no.3
• /
• pp.47-61
• /
• 2015

This study examined whether any differences can be found in desirable character traits and creative personality characteristics depending on the appearance management behaviors of male and female adolescents in Gwangju, South Korea. It was conducted by administering a self-report survey to 544 male and female middle school students. The collected survey data were analyzed by Means, Cronbach's ${\alpha}$, Factor analysis, One-way ANOVA, and Duncan-test using the SPSS/PC WIN 19.0 statistical program. The results were as follows: According to the results of the survey, total coordination seeking in appearance management behavior is very important to teens and is deeply related to desirable character traits and creative personality characteristics. Desirable character traits show positive results for basic living habits, filial piety, respect and affection. Creative personality characteristics show positive results for curiosity, open thinking, risk taking, assignment completion and esthetic appreciation. Considering these findings, there is a need for supplementary content on total coordination seeking behavior in home economics courses. Positive effects in terms of desirable character traits and creative personality characteristics can be expected through after class activities involving clothing habits or searching for a path in life and given the depth of education related to total coordination through a free semester system.

• Journal of The Korean Association For Science Education
• /
• v.38 no.6
• /
• pp.825-838
• /
• 2018

The purpose of this study is to develop a survey tool of scientific character for elementary student which connects science education and character education effectively by figuring out traits of elementary students' character being presented in teaching and learning context of elementary school science. For this, we adapted the theocratical model from the previous research which defined scientific character as the competencies being able to practice in concrete teaching and learning context of science. Based on this model, we developed the survey tool as 'Scientific Character Inventory for Elementary Student' to assess elementary students' scientific character as the competences to practice the virtues being pursued in the context of elementary school science and verified its reliability and validity. As a result of an exploratory and confirmatory factor analysis, we confirmed all the items could be summarized into 28 items and eight constructs such as scientific problem-solving, self-management, self-reflection, communication, interpersonal skill, community participation, global citizenship, and environmental ethics awareness. We found that minimum reliability coefficient of constructs was over than 0.5 and reliability coefficient of the total items was 0.878. And also, there was modest relationship between each construct and the total score of scientific character. These results show that the developed survey tool can be useful in evaluating the effectiveness of science character education. This study is meaningful in that it systematically reveals constructs of scientific character which can be raised in concrete context of science teaching and learning so as to suggest the survey tool to assess this.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.6
• /
• pp.53-62
• /
• 2013

A 5-20 cm thick shocrete has been routinely constructed for NATM tunneling method to stabilize and confine the excavated rock of tunnel construction site. A $40kg/m^3$ of steel fibers are usually mixed into such shotcrete but these steel fibers may not be evenly distributed depending on shotcrete machines, mixing ratios and excavated rock conditions. In this study, square column shotcrete-mimicked concrete specimens of $15cm{\times}15cm{\times}55cm$ were prepared with 5 equal layers and 5 or 20% cement ratio. The specimens were prepared with different reinforced-patterns: non-reinforced, middle layer-reinforced, 1, 3, and 5 layers-reinforced, or all layers reinforced. The specimens were air-cured for 7 days and tested for flexural strength. The influence of steel-fiber distribution on flexural strength and toughness of shotcrete-mimicked concrete specimens was investigated. In the case of a specimen with cement ratio of 20%, a flexural strength increased as a number of fiber-reinforced layer increased. The flexural strength of one-layer reinforced specimen showed 20% less than that of evenly fiber-distributed specimen. On the other hand, a specimen with cement ratio of 5% decreased as the number of fiber-reinforced layers increased. A toughness index increased as the number of fiber-reinforced layers increased, regardless of cement ratios. The toughness index of evenly fiber-distributed specimen showed 2-3 times as large as that of one-layer reinforced specimen.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.12 no.1
• /
• pp.51-60
• /
• 2010

Recently, a new type of polyolefin fiber having a good mechanical properties is being developed, and it is necessary to examine a possibility for the new fiber together to be used as a reinforcing fiber with other types of fiber or by itself. The objective of this study is to find flexural toughness and tensile strength of concrete reinforced with steel and polyolefin fibers. Four point beam tests were performed with 324 specimens following two standard tests methods: KS F 2566 and ASTM C 1399-02. From the test results, the effects of volume fraction of fibers, and aspect ratio of steel fiber on the toughness and tensile strength were investigated, and the optimal ratio of steel fiber to polyolefin fiber was suggested.

• Tunnel and Underground Space
• /
• v.14 no.5
• /
• pp.363-372
• /
• 2004

Double torsion (DT) tests were carried out to investigate the influence of the geometry of guide groove on stress corrosion index of Kumamoto andesite. The fracture toughness was measured in the constant displacement rate, which was set to 2.07 MN/m$^{3}$2/ in average regardless of crack velocity. Stress corrosion indices, n were evaluated using specimens with rectangular, circular and triangular grooves and were 37, 36 and 38 in average, respectively. The n values were constant regardless of the groove geometry, however the DT specimen with triangular groove geometry showed the largest standard deviation in the relationship between crack velocity and stress intensity factor. The DT test was found to be effective in using a rectangular-grooved specimen and the width of the groove must be greater than the average grain size of minerals.

• Journal of the Korean School Mathematics Society
• /
• v.22 no.4
• /
• pp.369-393
• /
• 2019

The purpose of this study is to find the commonality between process-focused assessment and existing performance evaluation and to find out whether the process-focused assessment is effective for the development of the character of school mathematics. By analyzing the previous research, this study defined the meaning of process-focused assessment as an evaluation that can improve students' growth and quality of class through immediate feedback by introducing various performance tasks and evaluation methods. The character of school mathematics refers to personality factors that are easily expressed and cultivated during math classes. Therefore, this study presented examples of the feasibility of process-focused assessment focusing on geometry and vector subjects and examined the effectiveness of mathematics and character development through process-based evaluation. Four course-based assessments (math experiments, logic, proof, and communication) aimed at cultivating the character of school mathematics were conducted from March to June 2019 for the third year of high school. The index was measured. Analysis of the results using the corresponding variable t-test showed that the process-based evaluation in this study had a significant effect on the character of school mathematics development.