• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.331-334
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• 2003

In the finite element simulation of hot forging processes using hexahedron, remeshing of a flash is very difficult. The mesh compression method is a remeshing technique to construct an effective hexahedral mesh. However, because mesh is distorted during the compression procedure or the mesh compression method, mesh smoothing is necessary to improve the mesh Qualify. in this study, several geometric mesh smoothing techniques and a matrix norm optimization technique are applied and compared which is more adaptive to the mesh compression method.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.39-47
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• 1995

The compression molding of SMC (sheet molding compund) at room temperature was analyzed based on rigid-viscoplastic approach by three dimensional finite element program. The developed program was tested by solving the three dimensional compression of wedge type specimens of aluminum alloys at various processing conditions. The simulation results were compared well to the experimental results available in the literature. based on this comparison the program was proved to be valid and was further applied in solving compression molding of SMC, which is a thermosetting material reinforced with chopped fiber glass. To investigate the effects of friction conditions and mold closing speeds for compression molding of SMC charge at room temperature, compressions of the cylindrical and rectangular shaped SMC were analyzed for various friction conditions and mold closing speeds. The calculated load values were compared to the experimental results for the compression molding of cylindrical specimen.

• Steel and Composite Structures
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• v.22 no.2
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• pp.217-234
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• 2016

In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• Transactions of Materials Processing
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• v.13 no.2
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• pp.180-187
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• 2004

A computer code was developed to simulate the filling stage of the injection/compression molding process by a finite element method. The constitutive equation used here was the compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. Simulations of a disk part under different process conditions including the variation of compression stroke and compression speed were carried out to understand their effects on birefringence variation. The simulated results were also compared with those by conventional injection molding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1172-1175
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• 2004

At present, CHS(Compression Hip Screw) is one of the best prosthesis for the intertrochanteric fracture. There is nothing to evaluate the CHS itself with the finite element analysis and mechanical tests. They have same ways of the experimental test of the ASTM standards. The purpose of this study is to evaluate the existing CHS and the new CHS which have transformational design factors with finite element analysis and mechanical tests. The mechanical tests are divided into compression tests and fatigue test for evaluating the failure load, strength and fatigue life. This finite element method is same as the experimental test of the ASTM standards. Under 300N of compression load at the lag screw head. There are less differences between Group (5H, basic type) and Group which has 8 screw holes. However, there are lots of big differences between Group and Group which is reinforced about thickness of the neck range. Moreover, the comparison of Group and Group shows similar tendency of the comparison of Group and Group . The Group is reinforced the neck range from Group. After the experimental tests and the finite element analysis, the most effective design factor of the compression hip screws is the reinforcement of the thickness, even though, there are lots of design factors. Moreover, to unite the lag screw with the plate and to analyze by static analysis, the result of this method can be used with experimental test or instead of it.

• Transactions of Materials Processing
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• v.4 no.3
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• pp.204-213
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• 1995

A finite element program is developed to analyze the flow phenomena in SMC compression molding as a viscoplastic model. The calculation of temperature distribution is also carried out by uncoupling the thermal analysis from the flow analysis. SMC molding processes with a flat plate substructure and the one with a T-shaped rib are considered in numerical simulation. The numerical results provide deformed shapes, temperature distribution in a SMC charge, and the forming load. The simulation of compression molding of a flat plate with a T-shaped rib requires a remeshing technique for the whole process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.488-499
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• 1996

SMC(Sheet molding compound) is a thermosetting material reinforced with chopped fiberglass. The compression molding of SMC was analyzed based on a rigid thermo-viscoplastic approach using a three dimensional finite element program coupled with temperatures. Only the temperature analysis part was tested in this paper by solving one-dimensional heat transfer problem and comparing with the exact solutions available in the literature. Based on this comparison the program was proved to be valid and was further applied in solving compression molding of SMC between flat dies. To investigate the usefulness of a rigid thermo-viscoplastic approach in the compression molding analysis of SMC charge, compression of rectangular shaped SMC charge at plane strain and three dimensionalde formation condition was analyzed under the same condition as given in the literature. From this comparison it was found out that the rigid thermo-viscoplastic approach was useful in analyzing SMC compression molding between flat dies.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.133-136
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• 1999

Many researches on the identification of a system have been carried out using a least square method, an adaptive filter, and so on. However, it is difficult to apply these methods in a nonlinear system. In the case of a nonlinear system, it is known that the signal compression method is able to estimate uncertain parameters of linear element in a nonlinear system because it is able to separate linear element and nonlinear element in a nonlinear system. However, the signal compression method cannot be applied to a motion simulator because actuators of the simulator is single-rod cylinders which includes expansion and compression dynamic properties. Therefore, this paper proposes a modified signal compression method which is able to estimate uncertain parameters of the motion simulator dynamics. The dynamic properties of this system are identified by separating expansion and compression properties when applying the signal compression method. And then, the identified parameters are applied to design a sliding mode controller for the simulator. The performance of the designed sliding mode controller is evaluated experimentally.

• International Journal of Concrete Structures and Materials
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• v.9 no.1
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• pp.21-33
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• 2015

This study aimed to present a reinforced concrete block system that reduces the flange thickness of the existing form block used in new buildings and optimizes the web form, and can thus capable of being used in the seismic retrofit of new and existing buildings. By conducting a compression test and finite element analysis based on the block and grouted concrete strength, it attempted to determine the compression capacity of the form block that can be used in new construction and seismic retrofit. As a result, the comparison of the strength equation from Architectural Institute of Japan to the prism compression test showed that the mortar coefficient of 0.55 was suitable instead of 0.75 recommended in the equation. The stress-strain relation of the block was proposed as a bi-linear model based on the compression test result of the single form block. Using the proposed model, finite element analysis was conducted on the prism specimens, and it was shown that the proposed model predicted the compression behavior of the form block appropriately.

• Journal of Biosystems Engineering
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• v.30 no.6 s.113
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• pp.347-353
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• 2005

Paper angle, environment friendly packaging material, has been mainly used as an edge protector, But, in the future, paper angle will be applied to package design of heavy product such as strength reinforcement or unit load system (ULS). Therefore. understanding of buckling behavior fur angle itself, compression strength and quality standard are required. The objectives of this study were to characterize the buckling behavior by theoretical and finite element analysis, and to develop compression strength model by compression test for symetric and asymetric paper angle. Based on the result of theoretical and finite element analysis, as applied load level was bigger and/or the length of angle was longer, incresing rate of buckling of asymmetric paper angle was higher than that of symmetric paper angle. Decreasing rate of minimum principal moment of inertia significantly increased as the extent of asymmetric angle increased, and buckling orientation of angle was open- direction near the small web. Incresing rate of maximum compression strength (MCS) for thickness of angle decreased as the web size increased in symmetric angle. MCS of asymmetric angle of 43${\times}$57 and 33${\times}$67 decreased $15{\~}18\%$ and $65{\~}78\%$, and change of buckling increased $12{\~}13\%$ and $62{\~}66\%$, respectively.