• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.736-741
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• 1992

The Stewart platform is one example of a motion simulator which generates 6 DOF motion in space by 6 actuators connected in parallel. The present SISO controllers are designed to track displacement command of each actuator computed from reference 6 DOF motion of platform by Stewart platform inverse kinematics. But this type of control can't cope with external load variation, geometric configuration of motion simulator, and different dynamic behavior of 6 DOF motion. In this paper, a multivariable controller using H- optimal control theory is designed for linerized simulator model with each actuator driving force as control input and platform 6 DOF motion as measured output. Nonlinear simulation result of the H$_{\infty}$ MIMO controller is not satisfied in steady-state characteristics. But the proposed H$_{\infty}$ + PI control scheme shows acceptable performance.e.e.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.5
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• pp.275-281
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• 2010

Car HVAC is one of main factors influencing a potential customer's first impression. It should be fault-free, which requires the most stable control performance. So, the control algorithm consists of a proportional feedback only, not with an integral action needed for elimination of steady-state errors. To reduce the errors and make the response faster, feedforward algorithm based on predicted thermal load is added. To evaluate the performance, car HVAC is dynamically modelled and its control logic is simulated. The results shows that the proportional feedback leads to about $4^{\circ}C$ of steady-state error. When the feedback is combined with the feedforward algorithm and with a set value update based on disturbances, it predicts less than $1^{\circ}C$ of control error and improved thermal comfort.

• Journal of KSNVE
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• v.8 no.3
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• pp.441-449
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• 1998

A self-tuning control scheme, incorporated with the simplified 1st-order ARMAX(Auto-Regressive Moving Average eXogenous) model, for single rod hydraulic cylinder which has varying dynamic characteristics is presented here. An adaptive controller is developed for the system that uses feedforward and optimal feedback control for simultaneous parameter identification and tracking control. Through experimental results, the performance comparison of the self-tuning controller with a fixed gain proportional controller clearly shows its superior ability in handling load changes in quiescent states.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.357-362
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• 2000

This Paper presents dynamic analysis of underground R/C Subway Structure, subjected to seismic actions. Earthquakes brought serious damage to RC subway Structure. Foe studying the collapse mechanism of underground RC Subway, seismic of a subway station is simulated in using FEM program ASP2000 of two-dimension based on the path dependent RC elastic model, soil foundation and interfacial models. The shear failure of intermediate vertical columns is founds to be the major cause of the structural collapse. According to FEM simulation of the failure mechanism, it is considered that the RC column would lose axial load carrying capacity after the occurrence of the localized diagonal shear cracks , and sudden failure of the outer frame would be followed. Specially, the shear stress in the middle slab reaches maximum shear capacity. So, the Structure would fail in the middle slab as a result of erasing the vertical ground motion computation.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.269-274
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• 1990

Usually, robot manipulators in production lines are operated with reperting work trajectories. This paper presents the repeated adaptive learning algorithm for robot manipulates for the case of a trajectory. This algorithm uses the nonlinear dynamic model including the repeated friction compensating term, The advantage of the scheme is that It allows friction compensation which may be otherwise difficult for differently constructed models. A secondary advantage of the sheme is that it can also adapt to torque calculation in order to reduce the computational load of the control computer. To show the efficiency of the proposed controller, a computer simulation is performed for the planar robot manipulator with a 2 degree of freedom.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.804-809
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• 2012

This paper presents the economic impact of consumer participation in Real-Time Pricing (RTP). A computer model was developed to analyze the impact of real-time pricing on the average price, electricity sales, and the social welfare. Four revenue reconciliation alternative were introduced to illustrate the effect of RTP. Finally a case study was done to analyze the consequent impact of the dynamic load profile on the long-term fuel mix, and the results were compared with those of $5^{th}$ national power development plan.

• Steel and Composite Structures
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• v.28 no.3
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• pp.381-388
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• 2018

In this paper, forced vibration of micro cylindrical shell reinforced by functionally graded carbon nanotubes (FG-CNTs) is presented. The structure is subjected to transverse harmonic load and modeled by beam model. The size effects are considered based on strain gradient theory containing three small scale parameters. The mixture rule is used for obtaining the effective material properties of the structure. Based on sinusoidal shear deformation theory of beam, energy method and Hamilton's principle, the motion equations are derived. Applying differential quadrature method (DQM) and Newmark method, the frequency curves of the structure are plotted. The effect of different parameters including, CNTs volume percent and distribution type, boundary conditions, size effect and length to thickness ratio on the frequency curves of the structure is studied. Numerical results indicate that the dynamic deflection of the FGX-CNT-reinforced cylindrical is lower with respect to other type of CNT distribution.

• Current Photovoltaic Research
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• v.4 no.4
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• pp.131-139
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• 2016

This paper shows the series power device in the massive roof-top PVs and domestic loads. D-UPFC as the series power device controls the distribution voltage during voltage rise (or fall) condition. D-UPFC consists of the bi-directional ac-ac converter and the transformer. In order to verify the D-UPFC voltage control, the distribution model is used in the case study. D-UPFC enables the voltage control in the distribution voltage range. Dynamic voltage control from voltage rise and voltage fall conditions is performed. Scaled-down experimental test of the D-UPFC is verified the voltage control and it is well performed without high voltage spikes in the inductive load.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.10-16
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• 2012

This study presents the effectiveness of a composite structure at improving blast resistance. The proposed composite structure consists of carbon fiber reinforced polymer (CFRP) and steel layers. While CFRP layer is used for blast energy reflection due to its high strength, steel layer is used for blast energy absorption due to its high ductility. A dynamic model is used to simulate the elastoplastic behavior of the proposed composite structure subject to blast load. Considering the magnitude variations of a blast event, the probability of failure of each layer is evaluated using reliability analysis. By assigning design probability of failure of each layer in the composite structure, the thickness of layers is optimized. A case study for the design of CFRP-steel composite structure subjected to an uncertain blast event is also presented.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.11
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• pp.103-106
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• 1991

A three-dimensional finite element model of a ligamentous two motion segments (L4-S1) was developed to investigate its dynamic response. A number of parameters like the intradiscal pressure, forces in ligaments. and across facet joints in response to a sinusoidal axial compression force (-360 N to -440 N at 5 Hz) were predicted. The increase in the parameters varied from 12% to as high as 50% in comparison to response for a static load of 400 N. The predicted parameters also revealed a distortion and a phase shift in comparison to the applied sinusoidal signal. These changes may lead to degenerative changes seen clinically in persons exposed to a chronic vibration environment over time.