• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.278-285
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• 1999

This paper utilizes the method of Q-parameterization control to design a controller which solves the problem of imbalance in magnetic bearing systems. There are two methods to solve this problem using feedback controal. The first method is to compensate for the imbalance forces by generating opposing forces on the bearing surface (imbalance compensation). The second method is to make the rotor rotate around its axis of inertia (automatic balancing);in this case no imbalance forces will be generated. In this paper we deal with only imbalance compensation. The free parameter of the Q-parameterization controller is chosen such that these goals are achieved. After the introduction of a model of the magnetic bearing system, we explain the Q-parameterization controller design of the magnetic bearing system with emphasis on the rejection of sinusoidal disturbance for imbalance compensation design. The design objectives are formulated as a linear equations in the controller free paramete Q. Finally, simulation and experimental results are presented and showed the robustness and effectiveness of the proposed controllers.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.6
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• pp.779-788
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• 2013

The load requirements should be known to design mechanical structure. This paper proposes a generation method of load requirements using U.S. military specification to design the external mounting structure of the helicopters of which the flight environments such as aerodynamic forces and inertia forces are unknown. In this study, the load requirements which were applied at the design of the pod structure for helicopter captive flight test could be computed by using this method. The validation of proposed method was confirmed from the test flight using developed pod system.

• Earthquakes and Structures
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• v.8 no.1
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• pp.205-224
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• 2015

A new method for designing moment resisting concrete frames failing in a global mode is presented in this paper. Starting from the analysis of the typical collapse mechanisms of frames subjected to horizontal forces, the method is based on the application of the kinematic theorem of plastic collapse. The beam section properties are assumed to be known quantities, because they are designed to resist vertical loads. As a consequence, the unknowns of the design problem are the column sections. They are determined by means of design conditions expressing that the kinematically admissible multiplier of the horizontal forces corresponding to the global mechanism has to be the smallest among all kinematically admissible multipliers. In addition, the proposed design method includes the influence of second-order effects. In particular, second-order effects can play an important role in the seismic design and can be accounted for by means of the mechanism equilibrium curves of the analysed collapse mechanism. The practical application of the proposed methodology is herein presented with reference to the design of a multi-storey frame whose pattern of yielding is validated by means of push-over analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.249-257
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• 2015

The KBC2009 first introduces the requirements about vertical unbalanced forces into the design for steel ordinary concentrically braced frames(steel OCBFs), which forces them to easily meet the target seismic performance, called as the life safety performance objective under design based earthquakes(DBEs) pursuing in the KBC2009. However, there is little information on the effects of vertical unbalanced forces to the collapse prevention performance objective under maximum considered earthquakes(MCEs) which is another target seismic performance level implicitly prescribed in ASCE 7-10. It is valuable that the collapse capacities of steel OCBFs designed according to the KBC2009 are investigated. In this paper, the collapse modes of inverted V shaped steel OCBFs excited by MCEs are investigated. The prototype buildings of 5 story steel OCBFs are designed with different site conditions and three types of unbalanced forces are considered in the design stages. The prototype buildings are evaluated their seismic performances and collapse modes by nonlinear static analyses and nonlinear dynamic analyses. Analysis results show that the unbalanced forces significantly affect the seismic performance of the prototype buildings and proper considerations of unbalanced forces are required to achieve the desirable collapse mode and the collapse prevention performance objective.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.971-974
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• 1992

The mobile robot may be composed of a robot and an AGV. In this paper, the ynamics of a robot part, such as reaction forces or required torques, are studied with assumption of the AGV in motion. These forces of a mobile robot are different from those of an industrial robot. A new robot is deigned and manufactured for the mobile robot.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.221-227
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• 2002

This paper deals with the mechanical stress analysis due to electromagnetic forces and the optimal design of the link considering the stress. The link in Interior Permanent Magnet Brushless Motor(IPM) have influence on both mechanical and magnetic performance. The decrease of the link thickness serves to improve the torque, whereas this decreases the strength of link. Therefore, it is necessary to determine the appropriate link thickness considering electromagnetic forces and thermal expansion. The effects of the variation of link thickness on the mechanical stress and the electromagnetic performance are analyzed by the structural and electromagnetic Finite Element Method. In addition, the mechanical structure design of the link is performed to reinforce the mechanical strength against magnetic forces while preserving a food magnetic torque.

• Journal of the Ergonomics Society of Korea
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• v.11 no.1
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• pp.81-92
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• 1992

A two-dimensional static biochemical model of lower extremity in the seated posture was developed to assess muscular activities of lower extremity required for a variety of foot pedal operations. We found that the double linear optimization method that has been used for modelling articulated body segments does no predict the forces generated by biarticular muscles reasonably, so the revised double linear optimization scheme was used to consider the synergistic effects of biarticular muscles in our model, assuming that the muscle forces are distributed proportionally based on their physiological cross sectional area. The model incorporated three rigid body se- gments with six muscles to represnet lower extremity. For the model validation, three male subjects performed the experiments in which EMG activities of six lower extremity muscles were measured. Predicted muscle forces were compare with the corresponding EMG amplitudes and it showed no statistical difference. The model being developed can be used to design and assess pedal and foot-related tool design.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.357-359
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• 1999

It is necessary for the optimum design of switching devices to calculate repulsion forces acting on the closed electric contacts flowing over-current, e.g. inrush current and overload currents. In this paper, the forces generated by currents and flux densities at the contact point when circuit breakers are in closed position are obtained by using 3D finite element method. According to the analysis, the optimum configuration of wipe springs and arc extinguishing chambers are newly designed and consequently type tests show satisfactory results.

• Proceedings of the ESK Conference
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• 1994.04a
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• pp.124-135
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• 1994

A biomechanical model of lower extremity in seated postures was developed to assess muscular activities of lower extremity involved in a variety of foot pedal operations. It is found that nonlinear optimization method which has been used for modeling the articulated body segments does not predict the forces generated from biarticular muscles reasonably, so the revised nonlinear optimization scheme was employed to consider the synergistic effects of biarticular muscles in the model, assuming that the muscle forces are distributed proportionally based on their physiological cross sectional area and moment arm. The model incorporated four rigid body segments with the nine muscles to represent lower extreimity. For the model valida- tion, three male subjects performed the experiments in which EMG activities of the nine lower extremity muscles were measured. Predicted muscle forces were compared with the corresponding EMG amplitudes and it showed no statistical difference. The developed model can be used to design and to assess the pedals and foot-related equipments design.

• Structural Monitoring and Maintenance
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• v.6 no.1
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• pp.1-17
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• 2019

Preserving reservoir safety has recognized to be important for the public where a vast majority of dams are located upstream of greatly populated cities and industrialized areas. Buckling, floatation and cavitation have caused failure in the spillway gates and conveyance features during past catastrophic events; showed their vulnerability and need for regular inspection along with reviewing design calculations to ensure the spillway meet current design standards. This paper investigates the hydraulic and structural consideration of dam's spillway by evaluating the data of Karkheh Dam's. Discharge capacity, flood routings and cavitation damage risk were main features for hydraulic considerations where hydrostatic and hydrodynamic forces and stability conditions were considered in structural considerations.