• Journal of Power Electronics
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• v.13 no.5
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• pp.814-828
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• 2013

The LCL resonant inductive power transfer (IPT) system is increasingly used because of its harmonic filtering capabilities, high efficiency at light load, and unity power factor feature. However, the modeling and controller design of this system become extremely difficult because of parameter uncertainty, high-order property, and switching nonlinear property. This paper proposes a frequency and load uncertainty modeling method for the LCL resonant IPT system. By using the linear fractional transformation method, we detach the uncertain part from the system model. A robust control structure with weighting functions is introduced, and a control method using structured singular values is used to enhance the system performance of perturbation rejection and reference tracking. Analysis of the controller performance is provided. The simulation and experimental results verify the robust control method and analysis results. The control method not only guarantees system stability but also improves performance under perturbation.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.866-875
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• 2006

The field plate load test a good potential for determining modulus since it measures both plate pressure and settlement. However, because The field plate load test is expensive and takes plenty of time for operation, it is very difficult to figure out the test characteristics of railroad roadbed in detail. For faster and economical operation, the Dynamic Cone Penetrometer(DCP) and the Light Falling Weight Deflectometer(LFWD) have been utilized for estimating the bearing capacity of railroad roadbed. The objective of this study is to determine the relationship between the test(PLT, DCP, LFWD) of the railroad roadbed in Korea. The DCP test and LFWD test for evauluating the strength of railroad roadbed materials produced in Korea are presented in this paper.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.2
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• pp.85-92
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• 2000

30 kVA rotating-field type Super-Conducting Generator is built and tested with intensive FE(Finite Element) analysis. The generator is driven by VVVF inverter-fed induction motor. Open Circuit Characteristic(OCC) and Short Circuit Characteristic(SCC) are presented in this paper. Also, the test result under the light load(up to 3.6 kW) are given. From the design stage, 2-D FE analysis coupled with the external circuit has been performed. The external circuit includes the end winding resistance and reactance as well as two dampers. When compared with the test data, the FE analysis results show a very good agreement.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2674-2677
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• 1999

Resonant converters have several salient features such as high efficiency and low noise. Therefore, ZVS-PWM controlled series resonant converter with active-clamp technique is presented. The combination of an active-clamp technique and resonant circuit makes it possible to control the output voltage of the resonant converter with PWM. This new resonant converter was implemented and has achieved a good controllability. In this paper, the normal load characteristics and abnormal voltage increase in the case of the light load are analyzed. As a result, it is clarified that the stray capacitance of the transformer is a cause of the abnormal voltage increase. Then, it is confirmed that the abnormal voltage increase is suppressed by decreasing the duty ratio. ZVS condition is analyzed. The maximum efficiency of 89% is obtained for the output of 10V and 5A.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1177-1179
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• 1999

This paper presents a design of artificial neural network power system stabilizer(ANNPSS) using adaptive evolutionary algorithm(AEA). We have proposed an adaptive evolutionary algorithm which uses both a genetic algorithm(GA) and an evolution strategy(ES), useing the merits of two different evolutionary computations. ANNPSS shows better control performances than conventional power system stabilizer(CPSS) in three-phase fault with heavy load which is used when tuning ANNPSS. To show the robustness of the proposed ANNPSS, it is applied to damp the low frequency oscillation caused by disturbances such as three-phase fault with normal and light load. the proposed ANNPSS shows better robustness than CPSS.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.70-74
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• 2003

The buck-boost converter is employed as the variable output PFC power stage. From the loss analysis, this topology has a high efficiency from light load to heavy load. A modified input current sensing scheme is presented to overcome the problem of the insufficient phase margin for the PFC circuit near the maximum output voltage. The variable output PFC circuit has a good performance in the wide output voltage range, under both the Boost mode when the output voltage is high and the Buck+Boost mode when the output voltage is low.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.1-8
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• 1994

In this paper, we hve compare the performance of DAR(Dynamic Adaptive Routing) with that of FSR(Flooding Search Routing) to select an adequate routing protocol in circuit-switched networs. As a performance factor, we have considered call setup time, which is the key factor of performance evaluation in circuit switched networks. We have evaluated the performance of two methods in grid topology circuit-switched networks using a commn channel signaling scheme, as application examples. As results, FSR method shows better performance than DAR method under light traffic load, when the number of links by which call has passed increases, but DAR method represents better performance than FSR method under heavy traffic load or large networks because of redundant packets.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.628-636
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• 2005

In this paper. the effects of a WI(Water Injection) in the intake pipe for a 4-cylinder Dl(Direct Injection) diesel engine are investigated experimentally, The WI system was controlled by the duty cycle from the intake manifold's temperature and MAF(Manifold Air Flow) First. effect of EGR on NOx reduction was investigated. Then WI system was applied to reduce NOx As the results. we can make the NOx map and visualize the NOx results by variation of engine speed and engine load It was known that effect of WI system on NOx reduction without the EGR was better than the with EGR base engine except of low load and speed condition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.353-359
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• 2009

Wire-woven Bulk Kagome (WBK) is a new truss type cellular metal fabricated by systematic assembling of helical wires in six directions. In this work, the experiments of mechanical behaviors of WBK cored sandwich panels subjected to bending load were performed and the results were compared with those by the corresponding analytic solutions. And also, finite element simulations were performed to validate the optimal design according to the analytic solutions. It is found the sandwich panel with WBK core performed excellently in terms of energy absorption and deformation stability after the peak point as well as the load capacity.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.113-122
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• 2004

Cable domes deform very largely because of the characteristics of flexible hybrid system and pre-tension, and include geometrical non-linearity in those structural behavior. Especially wind load is more dominant than seismic load, because cable domes are flexible structures whose bending stiffness is very small and self-weight is very light. Therefore, in this paper, the Modified Stiffly Stable Method is applied to analyze the nonlinear dynamic behavior of cable domes and compared these results with ones of the $Newmark-{\beta}$ Method which is generally used. The Seoul Olympic Gymnastic Arena is taken as an numerical example and three kinds of models with giving each different intensity of pre-tension are selected. And dynamic nonlinear behavior of cable domes are analyzed by artificial spectrum of wind velocity wave which is similar to actual wind loads.