• Journal of Drive and Control
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• v.13 no.3
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• pp.24-31
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• 2016

The performance characteristics of a dynamic control system are evaluated according to the transient and steady-state responses. The transient performance is the controllability of the output for the tracking of the reference or the ability to reduce or reject the effects of unwanted disturbances; alternatively, the steady-state performance is represented by the magnitude of the control error at the steady state. As the effects of the two performances on each other are reciprocal, a controller design that shows a zero steady-state error for the ramp input is uncommon because of the challenge regarding the achievement of an acceptable transient response. This paper proposes a PI+double-integral controller for the elimination of the steady-state error for the ramp input while a sound transient performance is maintained. The control-gain design procedure is described by the second-order response for the step input and the response of the error dynamics for the ramp input. The PI+double-integral controller is designed for the first-order transfer function that is derived from a system identification with the open-loop experiment data of the dc-motor. The simple structure of the proposed controller enables the adoption of a low-end microcontroller for the implementation of a real-time control. The experiment results show that the control performance is as effective as that of the simulation analysis for the operating point of linear system; furthermore, the PI+double-integral controller can be conveniently applied to the control system, which is desirable for the improvement of the steady-state error.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.11
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• pp.1071-1075
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• 2009

This article describes a robust control method by using peak control of a sensitivity function in the state-feedback control systems. This method apparently reduces the peak, and as a result makes closed loop systems more stable. The designed closed loop systems also make the response to an external step disturbance more fast with a lower undershoot. At the conclusion, it is verified that the proposed method enhances robust stability and robust performance to parametric uncertainties through $\mu$-plot.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.407-410
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• 1989

Optimizing transient response for both tracking reference signals and disturbance rejection is determined by the poles and zeros of the transfer function. Thus, optimal pole assignment and how should weighting matrix for the performance index be chosen is very important to achieve optimum transient response. This paper focus its attention on the choosing and analysis of weighting matrix for optimum pole assignment. Optimum pole assignment is defined for linear time-invariant continuous systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.396-406
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• 2007

In this paper, we proposed development of improved model reduction and design of hierarchical controller using reduction model. The model reduction is considered that it is the transient response and the steady-state response through the use of nyquist curve. The hierarchical controller selected tuning of PID controller to ensure specified gain and phase margin and hybrid smith-predictor fuzzy controller using reduction model. Simulation examples are given to show the better performance of the proposed method than conventional methods.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.10a
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• pp.7-10
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• 1984

In this paper, the advantages of buffer insertion access method in comparison with other access methods to local area networks are analyzed. Sending and Receiving protocols in a data link layer are designed by a software method, We have derived both qeueing delays and the response time for the performance model that is proposed in this paper, and using the computer simulation, analyzed the performance for the proposed model in terms of the throughput rate- response time characteristrics. Based on the proposed model, the hardware design is implemented.

• Journal of The Korean Association For Science Education
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• v.22 no.1
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• pp.122-131
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• 2002

Recently, performance assessment that makes growing use of free response items in a large scale assessment has been emphasized. This study is an empirical examination of the effectiveness of free response items in comparison with multiple choice items. Using the information function in Item Response Theory (IRT) framework, item information of free response items and multiple-choice items from the Third International Mathematics and Science Study-Repeat (TlMSS-R) were obtained. Test information of the whole science area as well as each area of science contents was computed. On average, free response items yielded more information than multiple choice items, especially in earth science, physics, chemistry, and life science. This study also showed that free response items were appropriate for students in high science ability. Also, free response items estimated students' science ability more accurately than multiple choice items with smaller number of free response items.

• Earthquakes and Structures
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• v.3 no.1
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• pp.59-81
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• 2012

A ductility inverse-mapping method for SDOF systems including passive dampers is proposed which enables one to find the maximum acceleration of ground motion for the prescribed maximum response deformation. In the conventional capacity spectrum method, the maximum response deformation is computed through iterative procedures for the prescribed maximum acceleration of ground motion. This is because the equivalent linear model for response evaluation is described in terms of unknown maximum deformation. While successive calculations are needed, no numerically unstable iterative procedure is required in the proposed method. This ductility inverse-mapping method is applied to an SDOF model of bilinear hysteresis. The SDOF models without and with passive dampers (viscous, viscoelastic and hysteretic dampers) are taken into account to investigate the effectiveness of passive dampers for seismic retrofitting of building structures. Since the maximum response deformation is the principal parameter and specified sequentially, the proposed ductility inverse-mapping method is suitable for the implementation of the performance-based design.

• Composites Research
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• v.23 no.2
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• pp.40-47
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• 2010

In this paper, the hybrid response surface method(HRSM) is proposed and examined. Hybrid response surface method calculate a approximate model repeatedly based on MPP coordinates. To verify the performance, probability of failure, MPP(Most Probable failure Point) and reliability index are calculated for nonlinear function and composite laminated plate by using reliability analysis method and compared with results by using typical response surface method(RSM). Probability of failure is calculated under the assumption of the nonlinear limit state equation and given failure criterion. The results of proposed method shows performance improvement in estimating the probability of failure.

• Structural Engineering and Mechanics
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• v.24 no.3
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• pp.275-290
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• 2006

In this paper, the performance of a tuned liquid damper (TLD) in suppressing the seismic response of buildings is investigated with shake table testing of a four-story steel frame model that rests on pile foundation. The model tests were performed in three phases with the steel frame structure alone, the soil and pile foundation system, and the soil-foundation-structure system, respectively. The test results from different phases were compared to study the effect of soil-structure interaction on the efficiency of a TLD in reducing the peak response of the structure. The influence of a TLD on the dynamic response of the pile foundation was investigated as well. Three types of earthquake excitations were considered with different frequency characteristics. Test results indicated that TLD can suppress the peak response of the structure up to 20% regardless of the presence of soils. TLD is also effective in reducing the dynamic responses of pile foundation.

• Journal of Korean Association for Spatial Structures
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• v.23 no.4
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• pp.27-34
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• 2023

In this study, the seismic response characteristics of the three analysis model with or without TMD were investigated to find out the effective dome shape. The three analysis models are rib type, lattice type and geodesic type dome structure composed of space frame. The maximum vertical and horizontal displacements were evaluated at 1/4 point of the span by applying the resonance harmonic load and historical earthquake loads (El Centro, Kobe, Northridge earthquakes). The study of the effective TMD installation position for the dome structure shows that seismic response control was effective when eight TMDs were installed in all types of analysis model. The investigation of the efficiency of TMD according to dome shape presents that lattice dome and geodesic dome show excellent control performance, while rib dome shows different control performance depending on the historical seismic loads. Therefore, lattice and geodesic types are desirable for seismic response reduction using TMD compared to rib type.