• Fire Science and Engineering
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• v.17 no.1
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• pp.26-32
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• 2003

Inert gases, Af, $N_2$, $CO_2$, as a Halon alternative, the empirical equations were correlated in terms of saturated pressure, density and viscosity, They were obtained by regression analysis from the experimental data in the literature. The empirical equations of saturated pressure were expressed as the second and third order function of temperature. The empirical equation for Ar and $N_2$ of density were expressed as the first order function of temperature. And $CO_2$ was expressed as the second and third order function of temperature. The empirical equation of viscosity was formulated as a power function with temperature. This empirical equations would allow us to predict pure component state.

• Smart Structures and Systems
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• v.21 no.1
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• pp.113-122
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• 2018

In this article, an exact analytical solution for mechanical buckling analysis of magnetoelectroelastic plate resting on pasternak foundation is investigated based on the third-order shear deformation plate theory. The in-plane electric and magnetic fields can be ignored for plates. According to Maxwell equation and magnetoelectric boundary condition, the variation of electric and magnetic potentials along the thickness direction of the plate is determined. The von Karman model is exploited to capture the effect of nonlinearity. Navier's approach has been used to solve the governing equations for all edges simply supported boundary conditions. Numerical results reveal the effects of (i) lateral load, (ii) electric load, (iii) magnetic load and (iv) higher order shear deformation theory on the critical buckling load have been investigated. These results must be the analysis of intelligent structures constructed from magnetoelectroelastic materials.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.247-249
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• 2008

There are many types of grid-connected inverter controllers; Synchronous Reference Frame (SRF)-based controller is the most popular methods. SRF-based controller is capable for reducing both of zero-steady state error and phase delay. However, SRF-based controller has a complex algorithm to apply in real application such as digital processor. Resonant controller is also reduced zero-steady state error, but its transfer function has a high order. In this paper, a simple proportional control is applied for grid connected inverter with LCL filter. LCL filter is a third order system. Applying a simple proportional controller is not increased the order of closed loop transfer function. By this technique, the single phase model is easily obtained. To reduce steady state error, proportional gain is set as high as possible, but it may produce instability. To compromise between a minimum steady state error and stability, the single phase model is evaluate through Root Locus and Bode diagram. PSIM simulation is used to verify the analysis.

• 한국전산유체공학회:학술대회논문집
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• 1997.10a
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• pp.86-91
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• 1997

This paper describes analysis of complex flow around Car-like body using Chimera grid technique. As a computational algorithm, Pullboat and Chaussee's Diagonal algorithm is selected to reduce computational time. Introducing hole points flag to this Diagonal algorithm, an algorithm for Chimera grid is generated easily. This study solves 3-D unsteady incompressible Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using second-order accurate schemes for the time derivatives, and third/second-order scheme for the spatial derivatives. The Marker-and-Cell concept is applied to efficiently solve continuity equation. The fourth-order artificial damping is added to the continuity equation for numerical stability, It has concluded that the results of present study properly agree with physical flow phenomena.

• Steel and Composite Structures
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• v.10 no.2
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• pp.129-149
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• 2010

The objective of this study is to formulate a general 3D material-structural analysis framework for the thermomechanical behavior of steel-concrete structures in a fire environment. The proposed analysis framework consists of three sequential modeling parts: fire dynamics simulation, heat transfer analysis, and a thermomechanical stress analysis of the structure. The first modeling part consists of applying the NIST (National Institute of Standards and Technology) Fire Dynamics Simulator (FDS) where coupled CFD (Computational Fluid Dynamics) with thermodynamics are combined to realistically model the fire progression within the steel-concrete structure. The goal is to generate the spatial-temporal (ST) solution variables (temperature, heat flux) on the surfaces of the structure. The FDS-ST solutions are generated in a discrete form. Continuous FDS-ST approximations are then developed to represent the temperature or heat-flux at any given time or point within the structure. An extensive numerical study is carried out to examine the best ST approximation functions that strike a balance between accuracy and simplicity. The second modeling part consists of a finite-element (FE) transient heat analysis of the structure using the continuous FDS-ST surface variables as prescribed thermal boundary conditions. The third modeling part is a thermomechanical FE structural analysis using both nonlinear material and geometry. The temperature history from the second modeling part is used at all nodal points. The ABAQUS (2003) FE code is used with external user subroutines for the second and third simulation parts in order to describe the specific heat temperature nonlinear dependency that drastically affects the transient thermal solution especially for concrete materials. User subroutines are also developed to apply the continuous FDS-ST surface nodal boundary conditions in the transient heat FE analysis. The proposed modeling framework is applied to predict the temperature and deflection of the well-documented third Cardington fire test.

• Journal of The Korean Association of Information Education
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• v.23 no.4
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• pp.283-292
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• 2019

In this study, an unplugged education method which focuses on the data visualization training was applied to third grade students of an elementary school and analyzed its impact on enhancing their computational thinking. The analysis was conducted on 60 elementary school teachers and 124 third grade students and the unplugged education program based on the data visualization procedure was developed. The education program developed was carried out with 24 third grade students for 36 hours over six days. The effect of the program applied was analyzed through the pre-to-post comparison performed with perceptive strength test and creativity test in order to examine the enhancement in computational thinking. According to the analysis result, the unplugged education method which focuses on the data visualization training has significant effect on the 'computational perception' and 'creativity' of third grade students.

• Journal of the Optical Society of Korea
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• v.2 no.2
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• pp.58-63
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• 1998

Cross-talk effects in high-density volume holographic interconnections are investigated using perturbative iteration method of the integral form of Maxwell's wave equation. In this method, the paraxial approximation and negligence of backward scattering introduced in conventional coupled mode theory is not assumed. Interaction geometries consisting of non-coplanar light waves and multiple index gratings are studied. Arbitrary light polarization is considered. Systematic analysis of cross-talk effects due to multiple index gratings is performed in increasing level of diffraction orders corresponding to successive iterations. Some numerical examples are given for first and third order diffraction.

• Journal of the Korean Society of School Health
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• v.6 no.2
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• pp.56-68
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• 1993

The primary school age are important period that the children exchange the deciduous teeth for permanent teeth, there are so many outbreak of dental caries which is major oral diseases periodontal disease begins, and malocclusion may be brought about. The purpose of this study is to suggest the fundamental data for enforcement of dental health in primary school age as analyzing the curriculum contents and amount on dental health in primary school course. The data were investigated from 103 volumes of 139 textbooks of second semester in 1992 and first semester i 1993 except some subjects that the quantitative analysis is impossible such as arithmetic a problem in arithmetic, observation, music, fine arts and so on. The contents of all textbooks were analyzed separating into paragraph and picture, the contents for dental health were classified into amount, item, teaching method. The results are as follows: 1) The paragraphs on public health were 3.992 among total paragraphs 69,789 as 5.72%. And the picture were 7.41% as 923 pieces of total 12,457 ones. 2) For dental health, there were 73 paragraphs of 69.789 ones (0.10%) and 42 pieces of 12.457 pictures (0.34%). 3) According to the investigation of curriculum that had the paragraphs related to dental health the most, it turned out to be in order of physical education nature. Right life story, and right life story, righ life, physical education for the picture. And for the grade, it appeared to be in order of sixth, third first grade for the paragraphs and first, third, sixth grade for the pictures. 4) In the attitude and knowledge of item for dental health by grade, it turned out that the paragraph was 76.71%, the behaviour was 23.29%. On the other hand, the knowledge was 35.17% and the attitude was 64.28% for the picture. 5) At the commentary of curriculum in primary school, the goal of health education by each grade was just keep clean and strong teeth, know the role of teeth and the cause of dacayed teeth, and prevent it in second and third grade.

• Journal of Sport and Applied Science
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• v.5 no.2
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• pp.63-71
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• 2021

Purpose: The purpose of this study, we will evaluate and analyze the importance and performance of Seongnam Football Club visitors using IPA analysis to present new marketing strategies and improvement plans based on the basis of the audience's perception of the team's priority, low priority, and excessive effort. Research design, data, and methodology: In order to achieve the purpose of the study, the survey was conducted on 120 home spectators of Seongnam Football Club, and the analysis of the data was conducted using SPSS Window Version 21.0. Data were analyzed via frequency analysis, exploratory factor analysis, corresponding sample t-test, and IPA analysis. Findings are as follows. Results: First, the first quadrant showed 'The convenience of access to the stadium', 'Parking lot convenience', 'Tournament schedule guidance', 'Providing information about player', 'Providing information about the team', 'Ticket reservation method'. Second, the second quadrant showed 'Players' fan service', 'Cleanliness of toilets', 'A player's level of performance', 'Team's level of play', 'A match against a rival team'. Third, the third quadrant showed 'Indication of facility guidance', 'Seat comfort', 'Team's Star Player Possession', 'Various participation events', 'Gift recommendation'. Fourth, the fourth quadrant showed 'Player-related promotion through media', 'Promote match schedules through media', 'Entrance convenience', 'Ticket Price'. Conclusions: Based on these findings, Factor in first quadrant, fourth quadrant should be kept. On the other hand, factors in second quadrant should be improved as soon as possible while factors in third quadrant can be improved through new marketing strategies in the future. Future implications were discussed.

• Structural Engineering and Mechanics
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• v.40 no.2
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• pp.191-213
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• 2011

This paper presents an improved 8-node shell element for the analysis of plates and shells. The finite element, based on a refined first-order shear deformation theory, is further improved by the combined use of assumed natural strain method. We analyze the influence of the shell element with the different patterns of sampling points for interpolating different components of strains. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. Further, a refined first-order shear deformation theory, which results in parabolic through-thickness distribution of the transverse shear strains from the formulation based on the third-order shear deformation theory, is proposed. This formulation eliminates the need for shear correction factors in the first-order theory. Numerical examples demonstrate that the present element perform better in comparison with other shell elements.