• Earthquakes and Structures
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• v.19 no.2
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• pp.103-117
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• 2020

The effect of the foundation size on the efficiency of seismic base isolation using a layer of stone pebbles is experimentally investigated. Four scaled models of buildings with different stiffnesses (from very stiff to soft) were tested, each with the so-called small and large foundation, and exposed to four different accelerograms (different predominant periods and durations). Tests were conducted so that the strains in the model remained elastic and afterwards the models were tested until collapse. Each model was tested for the case of the foundation being supported on a rigid base and on an aseismic layer. Compared to the smaller foundation, the larger foundation results in a reduced rocking effect, higher earthquake forces and lower bearing capacity of the tested models, with respectable efficiency (reduced strain/stress, displacement and increase of the ultimate bearing capacity of the model) for the considered seismic base isolation compared to the foundation on a rigid base.

• Journal of Distribution Science
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• v.10 no.12
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• pp.13-17
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• 2012

Purpose - The Asia-Pacific Economic Cooperation (APEC) forum has evolved and is actively facilitating free and open trade. It is debated whether APEC has effectively reduced trade barriers in a preferential manner to encourage liberalized trade and whether increased trade between member countries has reduced trade with nonmember countries. Research designs, data, methodology -This paper empirically tests whether APEC creates or diverts trade, using an extended gravity model with tariff rates, exchange rates, and dummy variables to analyze how APEC affects intra-trade between members.The model utilizes the annual panel data between 1990 and 2007 of 16 selected APEC members and nonmembers. Results - Results reveal the changing role of APEC only between 2002 and 2007 has it created trade, fostering increased trade among trading partners and between members and nonmembers. Conclusion - APEC can be expected to demonstrate a stronger trade creating effect once its advanced and developing members complete tariff reductions by 2010 and 2020, respectively.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1141-1143
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• 2001

This paper presents a detailed study of the reduced-model extended Kalman filter(EKF) for estimating the rotor speed of an induction motor drive. The general structure of the Kalman filter is reviewed and the various system vectors and matrices are defined. By including the rotor speed as a state variable, the EKF equations are established from a discrete two axis model of the three-phase induction motor, using the software MATLAB/Simulink, simulation of the EKF speed estimation algorithm is carried out for an induction motor drive with indirect vector control.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.823-826
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• 2001

A shape optimization of a rib of a bolster of a bogie frame is attempted and a dimension optimization on upper and lower plates is also carried out for the reduction of the weight of bogie frame. In addition, the dynamic characteristics of the weight reduced model are investigated by an analysis of a natural frequency and a transient analysis. The results show that the first natural frequency of an optimized model is larger than that of the lowest design value. And the results of transit analysis based on the experimental stress also show smaller value than the yield stress. Thus the optimized model attempted in this study is considered to be structurally stable and useful for the improvement of railway carriages.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.12-20
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• 2002

To control the noise of an enclosed sound field, we built a state space model using the acoustic modal parameter description. Using the state space model, we can investigate the controllability and observability, and find an appropriate position of control speaker and microphone to control sound field of the enclosed space. We implemented LQR(linear quadratic regulator) controller and reduced order observer to reduce the first acoustic mode. Experiments showed satisfactory results of 4∼10 dB reduction of magnitude of the first acoustic mode, and support the feasibility of the proposed scheme to lightly damped acoustic field.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.4
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• pp.583-589
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• 1987

A new approximation method is proposed for the linear model reduction of high order dynamic systems. This mehtod is based upon the denominator table(D-table) and time moment-matching technique. The denominator table(D-table) is used to obtain the denominator polynomial of reduced-order model, and the numerator polynomial is obtained by time moment-matching method. This proposed method does not require the calculation of the alpha-beta expansion and reciprocal transformation which should be calculadted by Routh approximation method. The advantages of the proposed method are that it is computationally every attractive better than Routh approximation method and the reduced model is stable Il the original system is stable.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.129-137
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• 2006

In this research, we made a one and two-dimensional analysis of numerical data collected from the bend curvature of a bended river section. According to the result from the numerical analysis, the inflow ＆ output angle caused a water level deviation which increased with an increase of the flood discharge. From the water level deviation of our two-dimensional numerical model, we obtained the maximum slope of 6,67% when the inflow and output angle was 105 degrees and the flood discharge was 500 CMS. As for the right side, the differences with the one-dimensional numerical model were reduced when the angle was more than $90^{\circ}$. As for the left side the differences were reduced when the angle was more than $105^{\circ}$. For a river with more than 90 degrees bend curvature, a hydraulic experiment would be more appropriate than a numerical analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.248-255
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• 2009

We proposed a power line channel model. We adopted advantages of other power line channel models to calculate channel responses correctly and simply. Infinite geometric series reduced the calculation complexity of the multipath signal propagation. Description Matrices were also adopted to handle the network topology easily. It represents complex power line network precisely and simply. Newly proposed model considered the effect of the adjacent nodes to channel responses, which have been not considered so far. Several simulations were executed to verify the effect of the adjacent nodes. As a result we found out that it affected channel responses but its effect was limited within certain degree.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.421-431
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• 2004

Line constants are composed by impedances and susceptances. A paper which was published estimated only impedances of line constants. Therefore, this paper estimates susceptances as well as impedances of equivalent five-conductors model using the reduced equivalent method. In order to verify estimated line constants, we measured line constants of real railway system. And we compared calculated results with measured data on 60Hz∼3000Hz. For the other verification, the calculation results from the proposed model and the measurement data from the test are compared focused on the amplification of harmonic current in the paper.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.366-369
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• 1994

In this paper, reduced-order $H_{\infty}$ robust controller is designed for the drum-type boiler system. From the known nonlinear dynamic model, a linearized multivariable model is obtained. To reduce order of robust controller, observer-based proper $H_{\infty}$ compensator is designed. The designed controller has robust property against the influence of sensor noise, system parameter variation and model uncertainty. A good Performance of the designed controller is shown by simulation.