• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.636-643
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• 2005

Recently, performance based seismic design (PBSD) methods have been suggested in numerous forms and widely studied as a new concept of seismic design. The PBDSs are far from being practical method due to complexity of algorithms resided in the design philosophy. In this paper, optimal seismic design method based on displacement coefficient method (DCM) described in FEMA 273 is developed. As an optimizer simple genetic algorithms are used for implementations. In the optimization problem formulated in this Paper, strength design criteria stiffness design criteria, and nonlinear response criteria specified in DCM are included in design constraints. The optimal performance based design(OPBD) method is applied to seismic design of a 3-story two-dimensional steel frame structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.429-434
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• 2008

The objective of this paper is to introduce a project on developing Finish Drawing Automation System. The system aims to improve efficiency of the BIM-based estimation, which is realized by automatic derivation of three-dimensional geometry models of the finish details. First, overall workload differences between the drawing-based estimation methods and the BIM-based methods are analyzed. Second, an automated finish detail design method is proposed as a time-saving measure for the BIM-based estimation, as manual modeling accounts for the most time spent in the model-based estimation process. Finally, the proposed system is evaluated using a case of washboard design.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.2
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• pp.82-90
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• 2008

In this paper, we introduce a biped walking robot which can do static walking with 22 degree-of-freedoms. The developed biped walking robot is 480mm tall and 2500g, and is constructed by 22 RC servo motors. Before making an active algorithm, we generate the motions of robot with a motion simulator developed using C language. The two dimensional simulator is based on the inverse kinematics and D-H transform. The simulator implements various motions as we input the ankle's trajectory. Also the simulator is developed by applying the principle of inverted pendulum to acquisite the center of gravity. As we use this simulator, we can get the best appropriate angle of ankle or pelvic when the robot lifts up its one side leg during the walking. We implement the walking motions which is based on the data(angle) getting from both of simulators. The robot can be controlled by text shaped command through RF signal of wireless modem which is connected with laptop computer by serial cable.

• Journal of Magnetics
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• v.19 no.1
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• pp.43-48
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• 2014

Magnetic materials with large coercive force and high squareness ratio are currently developing to meet an industrial demand. Since a ferromagnetic material has hysteresis characteristics, it is hard to demagnetize a ferromagnetic material precisely. In this paper, we describe deperm processes and conduct an analysis of residual magnetization of ferromagnetic material using the Preisach modeling with a two-dimensional finite elements method (FEM). From the results, it was shown that an exponential decrement form of deperm protocol is more efficient than a linear decrement form because of the demagnetizing field in the ferromagnetic material.

• Electronics and Telecommunications Trends
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• v.32 no.5
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• pp.65-73
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• 2017

A holography technique optically reconstructs a three-dimensional object in space to provide a natural sense of depth and volume to the observer, thereby providing an ultimate 3D image capable of solving the problem of "vergence-accommodation conflict" occurring in a conventional stereoscopic imaging system. In this paper, we present a technical framework for measuring the performance and evaluating the quality of a holographic display, which enables a quantitative measurement of the optical and physical properties that affect the performance and quality of a holographic display. In addition, we provide the trend regarding standardization related to holographic display measurements. Although this trend has barely started, research activities related to holographic display measurements and quality evaluations are expected to grow in the near future.

• Geomechanics and Engineering
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• v.14 no.6
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• pp.509-517
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• 2018

This paper proposes a numerical methodology for capturing the complete curve of a pressuremeter test including initial or disturbed parts and loops through a stiffness-based approach adopted in three dimensional finite difference code, FLAC3D. In order to enable this, a new hyperbolic model was used to replace the conventional linear elastic model prior to peak strength of Mohr-Coulomb soil model and update or degradation of shear modulus was considered. Presented modeling approach and implemented constitutive model are impressively successful. It leads to obtain the whole set of parameters for characterizing sands and seems promising for modeling the most of geotechnical structures.

• Structural Engineering and Mechanics
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• v.66 no.5
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• pp.665-676
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• 2018

In this study, a four-node quadrilateral partial mixed plate element with low degrees of freedom (dofs) is developed for static and free vibration analysis of functionally graded material (FGM) plates rested on Winkler-Pasternak elastic foundations. The formulation of the presented finite element model is based on a parametrized mixed variational principle which is developed recently by the first author. The presented finite element model considers the effects of shear deformations and normal flexibility of the FGM plates without using any shear correction factor. It also fulfills the boundary conditions of the transverse shear and normal stresses on the top and bottom surfaces of the plate. Beside these capabilities, the number of unknown field variables of the plate is only six. The presented partial mixed finite element model has been validated through comparison with the results of the three-dimensional (3D) theory of elasticity and the results obtained from the classical and high-order plate theories available in the open literature.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.3
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• pp.238-248
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• 1988

The flow pattern inside the power condenser is generally known to be very complicated due to the phase change and turbulence effects as well as the effect of condenser geometry. In the present study, the flow pattern inside the power condenser was numerically simulated with a personal computer. The widely known CHAMPION 2/E/FIX(Concentration, Heat and Momentum Program Instruction Outfit, 2D/Elliptic/Fixed grid) computer code was modified for this purpose. The flow was asssumed to be two-dimensional and steady-state, and the tube bank was considered to be homogeneous porous medium. Simple turbulent diffusion coefficients based on the appropriate experiments were obtained for the computation. Through this analytical approach, the flow pattern could be predicted fairly well. The computational results also show that the location of the air vent plays an important key role in determining the efficiency of the condenser.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.233-235
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• 2001

Residual stress in the forged parts affects the resistance to mechanical failure, dimensional uniformity, and the service life of the parts. In order to elucidate the development of residual stress in open-die forging process, elasto-plastic finite element analysis was implemented to radial forging process. Super duplex stainless steel SAF 2507 was selected as workpiece material and a series of mechanical tests followed by numerical compensation to deformation heating was conducted to obtain necessary flow data. The residual stress distributions were calculated using commercial 3-D FEM code and the effects of process design were evaluated from selected results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.47-50
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• 2003

Hot-forging Process and die design was made for a large-scale compressor wheel of Ti-6Al-4V alloy with 2-D FE analysis. The design integrated the geometry-controlled approach and dynamic materials modelling(DMM). In order to obtain the processing contour map of Ti-6Al-4V alloy based on DMM, compression tests were carried out in the temperature range of 915$^{\circ}C$ to 1015$^{\circ}C$ and the strain range of 10$\^$-3/s$\^$-1/ to 10s$\^$-1/. In the die design of the compressor wheel using the rigid-plastic FE analysis, forging dimensional accuracy, the capacity of the forging machine and defect-free forging were considered as main design factors. The microstructure of hot forged wheel using the designed die showed a typical alpha-beta structure without forging-defects.