• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.81-94
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• 2007

In most experimental researches on the liquefaction phenomenon, an earthquake as a random vibration has been regraded as a sinusoidal wave or a triangular wave with an equivalent amplitude. Together with the development in the part of signal control and data acquisition, dynamic experimental equipments in the soil dynamics have also developed rapidly and further more, several real earthquakes have been simulated in the large model test such as shaking table tests and centrifuge tests. In Korea, several elementary laboratory tests to simulate the real earthquake load were performed. From these test results, it was reported that the sinusoidal wave cannot reliably reflect the soil dynamic behavior under the real earthquake motion. In this study, 4 types of dynamic motions such as the sinusoidal wave, the triangular wave, the incremental triangular wave and several real earthquake motions which were classified with shock-type and vibration-type were loaded to find something new to explain the change of the excess pore water pressure under the real earthquake load. Through the detailed investigation and comparison on all test results, it is found that the dynamic flow is generated by the soil plastic deformation and the velocity head of dynamic flow is changed the pressure head in the un-drained condition. It can be concluded that the change of the excess pore water pressure is related to the pressure head of dynamic flow. Lastly, a new hypothesis to explain such a liquefaction initiation phenomenon under the real earthquake load is also proposed and verified.

• Korean Journal of Child Studies
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• v.38 no.3
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• pp.65-73
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• 2017

Objective: This study aimed to investigate the moderating effects of peer competence between children's perception of parenting attitudes and depression among $5^{th}$ grade elementary students. The differences are examined based by gender. Methods: 'The Children's Perception of the Parenting Attitudes Inventory', 'Children's Depression Inventory', and 'Peer Competence Inventory' were used to collect data from 200 elementary school students from Seoul, Korea. The research hypothesis were analyzed using t-tests, Pearson's correlation analysis, standard linear regression analysis and hierarchical multiple regression analysis via SPSS 21.0. Results: The results are as follows: First, only peer competence showed a difference between the boys and girls, where the boys scored higher than the girls. Second, there was a significant correlation between all the factors. Third, the moderating effect of peer competence on the father's parenting attitude was supported only in the boys. Conclusion: The results denote the need of a gendered approach to understanding problems and developing counseling programs to address depression among children. They also demonstrate that high peer competence can be used to treat depression in boys dissatisfied with their father' parenting attitude.

• Journal of Welding and Joining
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• v.9 no.1
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• pp.40-47
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• 1991

The most fatigue tests carried out under the either stress or strain control, but machines and structures had taken variable stress. This variable stress was treated as statistics based on p-type distributions. In this paper, the cumulative fatigue damage of SM45C round bar specimens having a center hole resulting from block loading with p-distributions in rotating bending conditions, is presented. The value of p was changed in the range from 0.25 to 1; 0.25, 0.5, 0.75, 1. The following conclusions were obtained through the constant stress amplitude experiments and the block loading experiments. (1) In constant loading test, fatigue life was affected by cyclic rate. From experimental data, N$_{f}$ (100cpm)/N$_{f}$(3000cpm)equal to 0.56. (2) In case of the cyclic rate 100cpm and 3000cpm, at the high stress amplitude level the crack propagation life N$_{*}$f is longer than the low stress amplitude level. (3) Miner's hypothesis may be valid for p=0.75 and prediction of fatigue life by Haibach's method agree with experimental data well for the case p=0.5, while the modified Miner's method agree with experimental data well for the case p=0.25.5.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.5
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• pp.15-21
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• 2002

We studied the relations between variables related to fan's preference in a area of pro-baseball which is the most popular one among pro-sports. The dependent variables are pro-baseball team fan's preference to both the team and the products of the company which has a pro-baseball team, while the independent variables are sex, age, and hometown of fans. Eight hypotheses are constructed with those variables. For testing them a questionnaire was used, whose reliability was checked using Kronbach Alpha. Subjects were 314 college students in a local city. For statistical analysis nonparametric tests like Mann Whitney test, Kruskal-Wallis test, etc were used. Useful and significant results among variables were obtained. Since these results have important implications about management of pro-sports teams and fans and fans Preference to products in a view of sports marketing management, more researches should be done continuously in the future in this area.

• Journal of Korean Elementary Science Education
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• v.17 no.2
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• pp.103-111
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• 1998

The purpose of this study was to investigate the relationship among spatial ability, learning styles, visual-perception- recall abiltiy, and the conceptual construction of the earth and moon's motion. Four paper-and-pencil tests were used to measure students' cognitive variables. Spatial ability was measured by Spatial Visualization Test, visual-perception-recall ability was measured by Rey's Figure which also have used to test visual- perception-recall ability of right-temporal lobes, and VVT were used to investigate students' learning styles. further, the test of concept construction was consisted of 15 items about the earth and moon's motion developed by researcher One hundred and twenty-seven 6th-, one hundred and sixteen 7th-, eighty-seven 9th-grade, ninety-three college students were participated in the investigation of the effects of age and learning style on conceptual construction. In the analysis of students' performances, spatial ability, visual-perception-recall ability, and conceptual achievement showed an increasing pattern with grading. In addition, visual learner's conceptual achievement showed a significantly higher score on conceptual test than verbal learner's(p<0.05). The results of the present study supported tile hypothesis that learning styles would differently influence to learning atmospheric concepts by students'learning styles. This study also indicated to be considered the students' spatial ability in learning atmospheric concepts.

• The Journal of Information Systems
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• v.19 no.4
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• pp.111-136
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• 2010

This study examined the difference in the usage of internet banking users between Korea and China. This model tests various theoretical research hypotheses relating to internet banking, The Unified Theory of Acceptance and Use of Technology(UTAUT). The factors influencing on the use intention of Internet banking have been classified as performance expectancy, effort expectancy, social influence and facilitating conditions. The proposed model was empirically tested using data collected from a survey of internet banking users in Korea and China. The model is used by SPSS 15.0 and AMOS 7.0 for analysis on the sample collected from 272 respondents. The result of hypothesis testing are as follows. First, performance expectancy and social influence positively influence use intention of internet banking user both Korea and China. Second, facilitating conditions only positively influence on the usage of internet banking users in Korea. On the other side, effort expectancy do not influence the use intention of internet banking users in both two countries. The results of study will provide practical implications on the internet banking in Korea and China.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3856-3862
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• 2009

The aim of this study is to examine the factors influencing managerial performances of women entrepreneur's characteristics and entrepreneurial supporting policy. This model tests various theoretical research hypotheses relating to characteristics of women entrepreneurs and an entrepreneurial supporting policy. The model is used by SPSS 15.0 for analysis on the sample collected from 130 respondents. The result of hypothesis testing are as follows: need for achievement, risk-taking propensity, vision, opportunity perception and entrepreneurial supporting policy influence positively managerial performances. The results of this study will provide practical implications on success of women entrepreneurs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3775-3781
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• 2009

This aims of this study is to examine the factors influencing on the channel satisfaction and preference of the mobile commerce. This model tests various theoretical research relating to technology acceptance model(TAM), transaction cost theory and service quality. The model is tested Structural Equation Modeling(SEM) using AMOS 7.0 analysis on the sample collected from 320 respondents. The result of hypothesis testing is as follows. First, usefulness, asset specificity, uncertainty, trust and responsiveness were influenced by channel satisfaction. Second, channel satisfaction was influenced positively by channel preference.

• Computers and Concrete
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• v.14 no.2
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• pp.145-161
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• 2014

The article presents the statistical method of grouping the results of the compressive strength of concrete in continuous production. It describes the method of dividing the series of compressive strength results into batches of statistically stable strength parameters at specific time intervals, based on the standardized concept of "concrete family". The article presents the examples of calculations made for two series of concrete strength results, from which sets of decreased strength parameters were separated. When assessing the quality of concrete elements and concrete road surfaces, the principal issue is the control of the compressive strength parameters of concrete. Large quantities of concrete mix manufactured in a continuous way should be subject to continuous control. Standardized approach to assessing the concrete strength proves to be insufficient because it does not allow for the detection of subsets of the decreased strength results, which in turn makes it impossible to make adjustments to the concrete manufacturing process and to identify particular product or area on site with decreased concrete strength. In this article two independent methods of grouping the test results of concrete with statistically stable strength parameters were proposed, involving verification of statistical hypothesis based on statistical tests: Student's t-test and Mann - Whitney - U test.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.569-589
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• 2007

This paper presents an analytical model for RC beam-column connections that takes into account bond deterioration between reinforcing steel and concrete. The model is based on the Lumped Damage Mechanics (LDM) theory which allows for the characterization of cracking, degradation and yielding, and is extended in this paper by the inclusion of the slip effect as observed in those connections. Slip is assumed to be lumped at inelastic hinges. Thus, the concept of "slip hinge", based on the Coulomb friction plasticity theory, is formulated. The influence of cracking on the slip behavior is taken into account by using two concepts of LDM: the effective moment on an inelastic hinge and the strain equivalence hypothesis. The model is particularly suitable for wide beam-column connections for which bond deterioration dominates the hysteretic response. The model was evaluated by the numerical simulation of five tests reported in the literature. It is found that the model reproduces closely the observed behavior.