• Structural Engineering and Mechanics
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• v.64 no.5
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• pp.591-610
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• 2017

This paper is concerned with the static analysis of variable thickness of two directional functionally graded porous materials (FGPM) circular plate resting on a gradient hybrid foundation (Horvath-Colasanti type) with friction force and subjected to compound mechanical loads (e.g., transverse, in-plane shear traction and concentrated force at the center of the plate).The governing state equations are derived in terms of displacements based on the 3D theory of elasticity, assuming the elastic coefficients of the plate material except the Poisson's ratio varying continuously throughout the thickness and radial directions according to an exponential function. These equations are solved semi-analytically by employing the state space method (SSM) and one-dimensional differential quadrature (DQ) rule to obtain the displacements and stress components of the FGPM plate. The effect of concentrated force at the center of the plate is approximated with the shear force, uniformly distributed over the inner boundary of a FGPM annular plate. In addition to verification study and convergence analysis, numerical results are displayed to show the effect of material heterogeneity indices, foundation stiffness coefficients, foundation gradient indices, loads ratio, thickness to radius ratio, compressibility, porosity and friction coefficient of the foundation on the static behavior of the plate. Finally, the responses of FG and FG porous material circular plates to compound mechanical loads are compared.

• Journal of Welding and Joining
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• v.30 no.5
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• pp.57-63
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• 2012

The purpose of this study is to evaluate the welding distortion of the circular type lap joint in STS304L of 0.7mm thickness by using FEA. In order to do it, a heat input model for GTA welding process with non-consumable electrode was established through comparing the molten pool shapes and temperature distributions obtained by both FEA and experiment. With the heat input model, the welding distortion of the circular type lap joint was evaluated by 3-D FEA. From FEA results, it was found that 3-D FEA with proper heat input model can be used for the evaluation of the excessive distortion of the circular type lap joint of STS304L thin plate. In addition, the root cause of the excessive distortion in the weld was also identified as the excessive compressive residual stress in the tangential direction of the weld.

• Journal of the Korean Data and Information Science Society
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• v.21 no.2
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• pp.241-250
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• 2010

Over the past few decades, several studies have been made on the modeling of circular data. But these studies focused mainly on the symmetrical cases including von Mises distribution. Recently, many studies with skew-normal distribution have been conducted in the linear case. In this paper, we dealt the problem of fitting of non-symmetrical circular data with wrapped skew-normal distribution which can be derived by using the principle of wrapping. Wrapped skew-normal distribution is very flexible to asymmetical data as well as to symmetrical data. Multi-modal data are also fitted by using the mixture of wrapped skew-normal distributions. To estimate the parameters of mixture, we suggested the EM algorithm. Finally we verified the accuracy of the suggested algorithm through simulation studies. Application with real data is also considered.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.210-211
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• 2004

The effect of oscillating on the unsteady laminar flow past a circular cylinder is numerically investigated in the present study. Our study is to analyze the vortex formation behind a circular cylinder for different rotary oscillation conditions. And then we are study to portray the unsteady dynamics of wake flows. We decide lock-on region by observing the phase switching phenomena We classify the vortex formation patterns in the primary lock-on region The present study is to identify the quasi-periodic state around lock-on region. At the boundary between lock-on and non-lock-on the shedding frequency is bifurcated. After the bifurcation, one frequency follow the forcing frequency ($S_f$) and the other returns to the natural shedding frequency ($St_0$). In the quasi-periodic state, the variation of magnitudes and relevant phase changes of $C_L$ with forcing phase are examined.

• Steel and Composite Structures
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• v.43 no.6
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• pp.759-772
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• 2022

Concrete-filled double skinned steel tubular (CFDST) columns have been used to construct modern structures such as tall buildings and bridges as well as infrastructures as they provide better, lesser weight, and greater stiffness in structural performance than conventional reinforced concrete or steel members. Different shapes of CFDST columns may be needed to satisfy the architectural and aesthetic criteria. In the study, three-dimensional FE simulations of circular and elliptical CFDST columns under axial compression were developed and verified through the experimental test data from the perspectives of full load-displacement histories, ultimate axial strengths, and failure modes. The verified FE models were used to investigate and compare the structural performance of CFDST columns with circular and elliptical cross-section shapes by evaluating the overall load-deformation curves, interaction stress-deformation responses, and composite actions of the column. At last, the accuracy of available design models in predicting the ultimate axial strengths of CFST columns were investigated. Research results showed that circular and elliptical CFDST column behaviors were generally similar. The overall structural performance of circular CFDST columns was relatively improved compared to the elliptical CFDST column.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.384-390
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• 2022

Objective: The purpose of this study was to investigate the effect of the side-step tasks based circular training program (STCT) on balance and gait characteristics in stroke patients. Design: A randomized controlled trial Methods: Twenty-four stroke patients were randomly divided into two groups of twelve patients each. One group was applied with the STCT whereas the other group was treated with conservative physiotherapy (CP). The ability of gait was measured in 10m walking test and stride length on both side using BTS G-WALK (BTS Bioengineering S.p.A, Italy) and the ability of balance was measured in Berg Balance Scale (BBS) and Timed Up and Go Test (TUG). Results: The STCT group was significant differences in the balance parameters of BBS and TUG (p<0.05) and showed significant differences in gait variables in 10m walking speed, stride length of affected and non-affected side after the experiment before and after the experiment (p<0.05). In addition, the STCT group showed a significant difference in BBS compared to the control group (p<0.05). Conclusions: The results of this study confirmed that the side-step tasks based circular training program (STCT) improves balance and walking ability in stroke patients. STCT is expected to be used as a useful intervention method for stroke rehabilitation.

• Resources Recycling
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• v.32 no.3
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• pp.45-56
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• 2023

This study analyzed the economic and environmental effect of recycling rhodium used in the non-catalytic field. As an analysis methodology, economic effect analysis applied cost-benefit analysis and resource-saving effect analysis and the environmental effect analysis applied life cycle assessment (LCA). The results show that from an economic point of view, the cost-benefit ratio was 1.28, which was feasible, and the cost reduction was 237,000 won based on 1 g of rhodium recycled and the amount of rhodium recycled was 7.17 billion won in 2025. As for the environmental effect, the greenhouse gas(GHG) emissions were compared between the case of recycling based on rhodium 1 kg and the case of overseas sales. The calculation results show that based on rhodium 1 kg, greenhouse gas emissions were reduced by 99.8%, from 65 kg CO₂eq./kg-Rh when recycling to 28,800 kg CO₂eq. when sold overseas. The results obtained from this study could suggest that rhodium recycling is necessary in Korea where resources are scarce by analyzing the economic and environmental effect of recycling rhodium used in the non-catalytic field.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.11-18
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• 2010

In this paper, We suggest new strategies on non-interactive agents applied in a prey pursuit problem of multi agent research. The structure of the prey pursuit problem by grid space(Four agent & one prey). That is allied agents captured over one prey. That problem has long been known in interactive, non-interactive of multi agent research. We trying hard to find its own solution from non-interactive agent method on not in the same original environment(circular environment). We used ACS applied Direction vector to learning and decide on a direction. Exchange of information between agents have been previously presented (an interactive agent) out of the way information exchange ratio (non-interactive agents), applied the new method. Can also solve the problem was to find a solution. This is quite distinct from the other existing multi agent studies, that doesn't apply interactive agents but independent agent to find a solution.

• Journal of Korean Association for Spatial Structures
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• v.7 no.2 s.24
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• pp.91-96
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• 2007

To improve the land use of urban, Construction of the circular steel column is required recently. The circular steel columns have a advantage for improving a load carrying capacity as wall as reducing a effective section area. However, the circular steel columns under service load, such as earthquake, shows a tendency to cause local buckling and large deformation. To prevent these phenomena, use of diaphragm is considered. It is reported that longitudinal stiffeners has a effect on improving a buckling and fatigue performance of steel structures. The research of effect on diaphragm is not sufficient. Under monotonic and cyclic loadings diaphragm make a important role to prevent local buckling and deformation of used steel structures. Therefore, influence of diaphragm on performance of used steel structures is investigated. In this study, the influence of diaphragm on seismic and deformation performance of circular steel piers was investigated by using elastic-plastic finite element analysis considered geometrical and material non-linearity. The seismic performance of circular steel columns was evaluated for analytical parameter of manufactured part. The seismic performance of circular steel columns was clarified by comparing an energy dissipation of circular steel piers.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.219-235
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• 2014

With the development of the technology of underwater moving bodies, the need for developing the knowledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free surface deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF) scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an external force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simulation errors of present work (using VOF method) for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.