• Proceedings of the KSME Conference
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• 2003.04a
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• pp.491-496
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• 2003

In sensitivity analysis, semi-analytical method(SAM) reveals severe inaccuracy problem when relatively large rigid body motions are identified for individual elements. Recently such errors of SAM resulted by the finite difference scheme have been improved by the separation of rigid body mode. But the eigenvalue should be obtained first before the sensitivity analysis is performed and it takes much time in the case that large system is considered. In the present study, by constructing a reduced one from the original system, iterative method combined with mode decomposition technique is proposed to compute reliable semi-analytical design sensitivities. The sensitivity analysis is performed by the eigenvector acquired from the reduced system. The error of SAM caused by difference scheme is alleviated by Von Neumann series approximation.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.2
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• pp.140-148
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• 2000

This paper presents iterative schemes and continuation schemes for designing robust controllers which stabilize dynamic systems having bounded parametric uncertainties. Utilizing results of the cheap control problem, some existence conditions of the robust controller are obtained, which are different from the matching conditions. continuation schemes are used to overcome the divergence problem of iterative schemes. The roust controller design method is extended to nonlinear system ans easily implementable series solution is also obtained. Results are illustrated with simple examples.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.1
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• pp.51-56
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• 1984

This paper describes the analysis and design of a GaAs FET distributed amplifier connecting a series capacitor to get a super wide bandwidth by reducing the gate line attenuation constant. In this approach a design example with a 300$\mu$ gate length FET devices is presented, and the abtained results are; that without series capacitors the bandwidth is 2-12 GHz, but with capacitors 2-20 GHz in flat gain.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1089-1094
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• 2016

In order to establish the robust controller design technique of series wound motor driver system. This paper proposes a method of Bang-Bang controller using a series wound motor driver system under improperly variable load. A Bang-Bang controller structure is simpler than the structure of PID plus Bang-Bang controller. This paper shows that a general 8 bits microprocessor is used efficiently implementing such an algorithm. The calculation time of software is extremely small when compared with conventional PID plus Bang-Bang controller. Both nonlinear operating characteristics of digital switching elements and describing function methods are used for the analysis and synthesis. Real time implementation of Bang-Bang controller is achieved. Concept design strategy of the control and PWM waveform generation algorithms are presented in the paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.20-28
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• 2009

This paper presents the design of zero current switching ZCS pulse frequency modulation type DC-DC converter for magnetron power supply. A magnetron serving as the microwave source in a microwave oven is driven by a switch mode power supply (SMPS). SMPSs have the advantages of improved efficiency, reduced size and weight, regulation and the ability to operate directly from the converter DC bus. The demands of the load system and the design of the power supply required to produce constant power at 4[kV]. A magnetron power supply requires the ability to limit the load current under short circuit conditions. The current source series resonant converter is a circuit configuration which can achieve this. The main features of the proposed converter are an inherent protection against a short circuit at the output, a high voltage gain and zero current switching over a large range of output power. These characteristics make it a viable choice for the implementation of a high voltage magnetron power supply.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.1
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• pp.15-22
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• 2001

In this paper, a VSC(Voltage Sag Corrector) is discussed for the purpose of power quality enhancement. A fast detecting technique of voltage sag is accomplished through the detection of instantaneous value on synchronous reference frame. A robust characteristic against the noise is available by inserting the first order low pass filter in the detection circuit. The formula and the filter design process is described properly with the mathematical equations. Because the VSC system supply the active power to load, it is required to design the proper size of the energy storage system, In this paper, the capacitor bank is used as an energy storage system, and the size of the capacitor is designed from the point of view of input/output energy as the output power rating and the amplitude and duration time of the voltage sag. The simulation is accomplished by PSCAD/EMTDC.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.396-398
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• 2005

At present, fatigue design of welded structures is primarily based on nominal stress or hot spot stress approach with a series of classified weld S-N curves. However, these methods are known to possess drawbacks, such as difficulty associated with defining proper nominal stress and the finite element sue sensitivity etc. Recently, a mesh-size insensitive structural stress definition is proposed by Battelle that gives a stress state at weld toe with relatively large mesh size. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of weld toe. As an experimental validation of the structural stress method in obtaining the fatigue strength of weldments, a series of experiment is carried out for various sizes of weldments. Based on the result from this study, it is expected to develop a more precise fatigue strength evaluation technique and to save time period required in the fatigue design of ship and offshore structures.

• ETRI Journal
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• v.39 no.6
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• pp.859-865
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• 2017

This paper presents a method for determining the optimum active-area width (OAW) of solar cells in a module architecture. The current density-voltage curve of a reference cell with a narrow active-area width is used to reproduce the current density profile in the test cell whose active area width is to be optimized. We obtained self-consistent current density and electric potential profiles from iterative calculations of both properties, considering the distributed resistance of the contact layers. Further, we determined the OAW that yields the maximum efficiency by calculating efficiency as a function of the active-area width. The proposed method can be applied to the design of the active area of a dye-sensitized solar cell in Z-type series connection modules for indoor and building-integrated photovoltaic systems. Our calculations predicted that OAW increases as the sheet resistances of the contact layers and the intensity of light decrease.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.8
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• pp.746-753
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• 2001

In this paper, we review the basic concept of Evolvable Hardware first. And we examine genetic algorithm processor and hardware reconfiguration method and implementation. By considering complexity and performance of hardware at the same time, we design genetic algorithm processor using modularization and parallel processing method. And we design frame that has connection structure and logic block on FPGA, and embody reconfigurable hardware that do so that this frame may be reconstructed by RAM. Also we implemented ECANS that information processing system such as living creatures'brain using this hardware reconfiguration method. And we apply ECANS which is implemented using the concept of Evolvable Hardware to time-series prediction problem in order to verify the effectiveness.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.69-73
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• 2010

In this paper, we designed the RF-DC converter used in wireless power transmission system and studied how to design the RF-DC converter of high conversion efficiency. The RF-DC converter operate at 2.45GHz and the diode is connected with series. The RF-DC converter uses shorted stub for DC loop and matching. We can divide the RF-DC converter circuit into four blocks. The reflection coefficients between the blocks were optimized for the maximum conversion efficiency at 0 dBm input power and $1300{\Omega}$ load impedance. The final design of the RF-DC converter has a 52 percent conversion efficiency.