• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.39-44
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• 2003

An unconditionally stable compact 2D Alternating-Direction Implicit (ADI) FDTD method for calculating dispersion characteristics of waveguide structures is proposed. The numerical stability and numerical dispersion relation of the proposed method are also presented and discussed. Numerical wavelengths for the dominant and higher order modes in a hollow waveguide are obtained from numerical simulations and compared with those from the analytical dispersion relation. The numerical results show that the proposed scheme has the potential to successfully analyze a class of waveguides having locally fine geometry with reduced numerical costs.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.947-952
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• 2001

The meso-scale microstructure of the $Ni-Ni_3Al- Ni_3V$ system is crucial to obtain both high strength and high toughness. Its evolution may be predicted with the aid of computer simulation of the compositional separation for heat-treated alloys. In this study, computer simulations of the hypothetical A-B-C ternary system, which is similar to the $Ni-Ni_3Al- Ni_3V$ system in terms of phase equilibria, have been performed using the kinetic modeling. Simulated morphologies were changed with nominal compositions and model parameters. It was showed the current model was useful and the more realistic model was proposed.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.4
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• pp.16-25
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• 2005

In this paper, we proposed a novel algorithm combined simulated annealing and genetic algorithms for designing optimal binary phase computer generated hologram. In the process of genetic algorithm searching by block units, after the crossover and mutation operations, simulated annealing algorithm searching by pixel units is inserted. So, the performance of BPCGH was improved. Computer simulations show that the proposed combined iterative algorithm has better performance than the simulated annealing algorithm in terms of diffraction efficiency

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.724-727
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• 1997

This paper describes a control method of tank level using Fuzzy Inference Technique. In General, to control tank level without a dangerous overflow and with a high accuracy is difficult because of high order time delay and nonlinearity. None the less, the hardware controller using 80586 Microprocessor with DT-2801 board in this paper was successfully implemented, through a series of simulations and experiments, the superiority of the proposed fuzzy controller ta a conventional PID one was investigated.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.480-485
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• 2006

In this paper, the error investigation of a 3-dimensional GPS attitude determination system using the error covariance analysis is given. New efficient formulas for computing the Euler Angle Dilution of Precision (EADOP) are also derived. The formulas are easy to compute and represent the attitude error as a function of the nominal attitude of a vehicle, the baseline configuration and the receiver noise. Using the formula, the accuracy of the Euler angle can be analytically predicted without the use of computer simulations. Applications to some configurations reveal the effectiveness of the proposed method.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1101-1104
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• 2002

In order to send the information certainly via the network against the packet lost caused by hardware troubles or limitation of packet transferring, we must construct reliable network infrastructure. However, it is difficult to construct comfortable network early if we construct rely on the prediction or the experience through a lot of troubles. In this paper, we propose the method to construct reliable network infrastructure based on the computer network simulation. This simulation is based on the percolation model. Percolation model is known as the model that represents connections. We gave some simulations for the various network topologies: the square lattice network, the cubic lattice network, and the full connection type network.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.7-10
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• 1998

Because of simple control algorithm and easy implementation, the conventional PI controller has been widely used in industrial application. But, it is very difficult to find the optimal PI control gain. Therefore, in improperly tuned PI controller or parameter variation, to obtain optimal performance, the novel PI controller, which consist of conventional PI controller and 4-rule based fuzzy logic, are presented in this paper. The novel PI controller which exhibits a stabilizing effects on the closed-loop system, has good robustness regarding the improperly tuned PI controller or parameter variation. The simulations are performed to verify the capability of proposed control method on induction motor.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3539-3558
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• 2015

This paper investigates and analyzes the default block placement strategy of HDFS. HDFS is a typical representative distributed file system to stream vast amount of data effectively at high bandwidth to user applications. However, the default HDFS block placement policy assumes that all nodes in the cluster are homogeneous, and places blocks with a simple RoundRobin strategy without considering any nodes' resource characteristics, which decreases self-adaptability of the system. The primary contribution of this paper is the proposition of a network load sensitive block placement strategy. We have implemented our algorithm and justify it through extensive simulations and comparison with similar existing studies. The results indicate that our work not only performs much better in the data distribution but also improves write performance more significantly than the others.

• Journal of electromagnetic engineering and science
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• v.15 no.2
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• pp.97-103
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• 2015

This paper investigates the effect of absorption loss by a human body to the received signal strength with respect to on-body transmitting antenna positions in on-to-off wireless body area networks. This investigation is based on measurement results obtained from experiments performed on human bodies (male and female) using planar inverted-F antennas in an anechoic chamber. The total absorption loss by the human body is also presented through the SEMCAD-X simulations. Our investigation showed that the received signal strength becomes lower when the transmitting antenna is mounted at a specific position where more absorption loss is experienced. The statistical analyses of on-to-off body channel characteristics based on the measurement results are presented.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.503-512
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• 2006

This paper proposes a new configuration for the Unified Power Quality Conditioner, which has a DC/DC converter with super-capacitors for energy storage. The proposed UPQC can compensate the reactive power, harmonic current, voltage sag and swell, voltage imbalance, and voltage interruption. The performance of the proposed system was analyzed through simulations with PSCAD/EMTDC software. The feasibility of system implementation is confirmed through experimental works with a prototype. The proposed UPQC has ultimate capability to improve the power quality at the point of installation on power distribution systems and industrial power systems.