• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.545-555
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• 2002

This paper presents a matrix analysis to get the torsional behavior of core structures with torsional reinforcements. Based on simplified assumptions, formulae for the forces and displacements of cote structures subjected to three typical load cases, i.e. uniformly distributed torque, triangularly distributed torque and a concentrated torque at the top of the structure, are derived analytically. The behavior of the cote according to the variation of reinforcement locations is investigated to estimate the optimum locations of reinforcements to minimize the core rotations and bimoments. The results by the program MIDAS-GEN have shown that this analysis can give quite satisfactory results for structural models with torsional reinforcements. Although three dimensional analysis by computer has come within reach as a normal structural design procedure, its use as an optimization tool may not be desirable in view of the expense and time required. Formulae that we presented here can be used to estimate the torsional rotations and forces of practical cote structures at the preliminary design stages.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.55-65
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• 2002

Model tests were performed to investigate the mechanism of lateral earth pressure on a buried pipe, which was installed in a plastic flowing soil mass undergoing lateral movement. On the basis of failure mode tests, the equation of lateral earth pressure to apply Maxwell's visco-elastic model was proposed to consider the soil deformation velocity. Through a series of model tests of differential soil deformation velocity, lateral earth pressure of theoretical equation was compared with experimental results. When lateral soil movement was raised, the lateral earth pressure acting on buried pipe increases linearly with the soil deformation velocity. It shows that the lateral earth pressure on buried pipe is largely affected by soil deformation velocity. When plastic soil movement was raised, lateral earth pressure predicted by theoretical equation showed good agreement with experimental results. Also, coefficient of viscosity by theoretical equation had a good agreement with direct shear test results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.291-297
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• 2003

The aim of this research is to propose new framework for taxonomy of various business and its concept, due to the changes in market space. This framework is three-dimension cubic model, based on three concepts, business layer(BL), value chain(VC), and Real/Virtual(R/V) that symbolizes real environment and virtual(or cyber) space. And we showed that this framework is able to describe all expected(or existed) business types in certain industry by the combinations of BL-VC-R/V on three dimension. In addition, we suggested new definition of e-business and e-Logistics from view of BL-VC-R/V. In order to test availability, this framework was applied for logistics related business. and classified typical business types existed (or expected) in logistics area.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.389-395
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• 2003

The aim of this research is to propose new framework for taxonomy of various business and its concept. due to the changes in market space. This framework is three-dimension cubic model based on three concepts, business layer(BL), value chain(VC), and Real/Virtual(R/V) that symbolizes real environment and virtual (or cyber) space. We showed that this framework is able to describe all expected(or existed) business types in certain industry by the combinations of BL-VC-R/V on three dimension. In addition, we suggested new definition of e-business and e-Logistics from view of BL-VC-R/V. In order to test availability of framework, this framework was applied for logistics related business, and we classified typical business types existed (or expected) in logistics area.

• Journal of IKEEE
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• v.27 no.4
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• pp.587-600
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• 2023

This paper presents an optimal design of the slim type high frequency transformer used in the LLC DC to DC resonant converter for 65-inch UHD-TV with the rated power of 315W. This paper also performs an optimal design of the slim type high frequency through core loss analysis, AC winding loss analysis, and optimization design of the winding arrangement of the LLC resonant transformer. Particularly, the high-efficiency and slim type high frequency transformer based on the obtained results from theoretical analysis in this paper is constructed in the interleaved and vertical winding structures of its transformer to realize the winding method of automatic type and minimize AC winding loss. The primary and secondary windings of the slim type high frequency transformer the vertical winding structure proposed in this paper used the Litz-wire windings, PCB and copper plate windings, respectively. Finally, an optimal design of the slim type high frequency transformer proposed in this paper was carried out through the experimental results to confirm the validity of theoretical analysis based on the simulation results using Maxwell 2D and 3D tool.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.629-635
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• 2020

Using a sample of two-hundred thirty-eight employees in the service industry, this study examined the relationships between perceived similarity, leader-member exchange (LMX), envy, and deviant workplace behavior (DWB) drawing on social comparison theory. Specifically, the current study predicts that an individual who perceives similarity to co-workers whose LMX is higher is more likely to report lower levels of LMX by focusing on upward social comparison. In addition, the study examines the moderating effect of envy in the relationship between perceived similarity and LMX. The results of the study supported the hypotheses, implying that, first, envious feelings coming from lower levels of LMX positively predict DWB. Second, employee envy moderated the relationship between perceived similarity and LMX such that envious people who report being similar to their colleagues also report lower levels of LMX with their supervisors. This means that employees who reported lower levels of LMX with their supervisors, reported committing more DWB than their counterparts. Finally, LMX mediates the relationship between perceived similarity and DWB, indicating that individuals who view themselves similarly to their colleagues report lower levels of LMX with their supervisors and in turn commit more DWB. We believe that it highlights the need for employees to feel special in order to have unique attention by, and relationships with their supervisors. These results have implications and suggest the need for the further study of employee's negative emotions, LMX theory, and DWB.

• Geotechnical Engineering
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• v.13 no.6
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• pp.147-164
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• 1997

This study has the assumption that scale effects in rock mass properties are atrributed to the discontinuous and inhomogeneous nature of rock masses. In order to escape the general equivalent material approach applied to the concept of representative volume element, this study presents the new method considering irregular i oink geometry and arbitrary numbers of i oink and arbitrary joint orientations. Based on the theoretical approach, this theory is applied to a real engineering project. Showing the property variations with size of rock mass element, various numerical experiments about scale effect are conducted. Particularly, to prove the adequacy of the verification process in scale effect with nomerical method, and to investigate the detailed source of scale effect, 4 models with increas ins number of joints are tested. On the basis of the experimental results, the test results of scale effects in 3-D rock mass are presented. From these experiments the effects of the mechanical properties of rock joints on the scale effects in rock mass strength and elastic constants are discussed. To verify the mechanism of scale effects in jointed rock mass, two models with different j oink geometries are studied.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6B
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• pp.373-378
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• 2012

In this study, a new empirical equation for the transverse dispersion coefficient has been developed based on the theoretical background in river bends. The nonlinear least-square method was applied to determine regression coefficients of the equation. The estimated dispersion coefficients derived by the new equation were compared with observed transverse dispersion coefficients acquired from natural rivers and coefficients calculated by the other existing empirical equations. From a comparison of the existing transverse dispersion equations and the new proposed equation, it appears that the behavior of the existing formula in a relative sense is very much dependent on the friction factor and the river geometry. However, the new proposed equation does not vary widely according to variation of friction factor. Also, it was revealed that the equation proposed in this study becomes an asymptotic curve as the curvature effect increases.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.149-160
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• 2017

In hypothesis testing, the interpretation of a statistic obtained from the data analysis relies on a probabilistic distribution of the statistic constructed according to several statistical theories. For instance, the statistical significance of a mean difference between experimental conditions is determined according to a probabilistic distribution of the mean differences (e.g., Student's t) constructed under several theoretical assumptions for population characteristics. The present study explored the logic and advantages of random-resampling approach for analyzing event-related potentials (ERPs) where a hypothesis is tested according to the distribution of empirical statistics that is constructed based on randomly resampled dataset of real measures rather than a theoretical distribution of the statistics. To motivate ERP researchers' understanding of the random-resampling approach, the present study further introduced a specific example of data analyses where a random-permutation procedure was applied according to the random-resampling principle, as well as discussing several cautions ahead of its practical application to ERP data analyses.

• Journal of Elementary Mathematics Education in Korea
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• v.16 no.2
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• pp.253-267
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• 2012

In this paper, we primarily focus on the perspectives about creative process, which is how mathematical creativity emerged, as one aspect of mathematical creativity and then present a desirable task characteristic to measure and program characteristics to develop mathematical creativity. At first, we describe domain-generality perspective and domain-specificity perspective on creativity. The former regard divergent thinking skill as a key cognitive process embedded in creativity of various discipline domain involving language, science, mathematics, art and so on. In contrast the researchers supporting later perspective insist that the mechanism of creativity is different in each discipline. We understand that the issue on this two perspective effect on task and program to foster and measure creativity in mathematics education beyond theoretical discussion. And then, based on previous theoretical review, we draw a desirable characteristic on instruction program and task to facilitate and test mathematical creativity, and present an applicable task and instruction cases based on Geneplor model at the mathematics class in elementary school. In conclusion, divergent thinking is necessary but sufficient to develop mathematical creativity and need to consider various mathematical reasoning such as generalization, ion and mathematical knowledge.