• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1314-1319
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• 2010

The excitation control system of an emergency diesel generator is classified as a kind of safety-related system. Compared with other control systems in a power plant, this system is required to be more reliable and have better performance. KEPCO Research Institute successfully developed the excitation control system for a diesel generator. This paper presents its field test results by using a real time simulator on a nuclear power plant.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.517-518
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• 2023

최근 뇌-컴퓨터 인터페이스 분야에서는 뇌파 신호를 이용한 운동 심상 분류 연구가 활발히 이루어지고 있다. 뇌파는 개인별 차이가 큰 생체 신호로, 사용자에 독립적인 경우 추론이 어려워지는 문제가 있어 운동 심상 분류에서는 주로 피험자 종속적인 연구가 행해져 왔다. 본 논문에서는 컨볼루션 신경망 기반의 뇌파 분류 모델인 EEGNet 에 새로운 방식으로 개선한 Squeeze-and-Excitation block 을 적용해 피험자에 대해 독립적인 운동 심상 분류 성능을 향상시키는 방법을 제안하며, 제안한 Squeeze-and-Excitation block 을 적용한 모델이 기존 모델보다 높은 분류 성능을 보여주는 것을 실험적으로 확인하였다.

• Structural Engineering and Mechanics
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• v.89 no.6
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• pp.549-556
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• 2024

A serial pendulum dynamic vibration absorber (DVA) was designed to suppress the vibration of two degrees of freedom (Two-DOF) structure model. The optimal DVA parameters are selected using a genetic algorithm (GA) by minimizing the fitness function formulated from the system's frequency response function (FRF). Two fitness function criteria, using one and two target frequency ranges, were utilized to calculate the optimal DVA parameters. The optimized serial pendulum DVA parameters were used to reduce structural vibration under free and forced excitation conditions. The simulation study found that the serial pendulum DVA can effectively reduce the vibration response for a small excitation amplitude. However, the DVA performance decreases for a large excitation amplitude due to the nonlinearity of pendulum motion, and the percentage of vibration response attenuation is smaller than that obtained using a small excitation amplitude.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.431-440
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• 2000

This paper analyses the dynamic performance of HVDC System connected to a weak AC system for various exciter characteristics of synchronous machines connected at the converter bus. Conventionally capacitors are used to supply reactive power requirement at a strong converter bus. But the installation of synchronous machine is essential in a isolated weak network to re-start after a shutdown of HVDC and to increase system strength. The dynamic performance of a synchronous machine depends on the characteristics depends of its exciter. In this paper, several exciter types are used to investigate their effect on the dynamic performance of the HVDC system and modifications to standard exciter topologies are suggested to mitigate observed problems.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.4
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• pp.292-302
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• 2003

We propose a new method to reduce the complexity of excitation codebook search. The preselected excitation pulses by the coarse search method can be updated to pulses with higher quality performance measure. The excitation pulses can arbitrarily be deleted and inserted among the searched pulses until the overall performance achieves. If we use this excitation pulse search method in AMR-WB, the complexity required for excitation codebook search can be reduced to half the original method while the output speech maintains equal speech quality to a conventional method.

• Journal of Korean Association for Spatial Structures
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• v.8 no.2
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• pp.95-103
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• 2008

This paper is concerned with the damping ratios of two methods, which are frequency domain and time domain approach. Ambient vibrations and synchronized human excitation test were conducted to three reinforced concrete buildings ranging from eleven to nineteen stories. The performance of the half power bandwidth method was investigated using three kinds of sample size, 1024, 2048, and 4096. The damping ratio by synchronized human excitation ranges from 1.05% to 1.22% in the long direction and from 1.16% to 1.50% in short direction. Damping by half power bandwidth method is slightly more overestimated than the synchronized human excitation due to insufficient record length. Damping evaluation by half power bandwidth method was found to be enhanced by using the narrower bandwidth with long recorded data.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.655-662
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• 2011

For analyzing seismic performance of long-span bridge for multi-support excitation and preparing technically and efficiently for a variety of design demands, the new module on multiple excitation was built in a reliable non-linear analysis program(RCAHEST) by using Influence Line Method, and the study on structures was performed previously. Also, the result of the analysis through RCAHEST was compared and verified with commercial finite element analysis program SAP2000 by using the feature of Multi-Support Excitation. From these results, nonlinear time history analysis considering multi-support excitation was studied after designing FE model of Incheon cable-stayed bridge. It was proved that the maximum response of horizontal displacement decreased as the time delay was increasing at all nodes of bridge. And then the serviceability of analysis model was evaluated by performing ultimate analysis under changes in maximum acceleration of seismic load data.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.3
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• pp.134-140
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• 2022

Ship local structure sometimes experiences severe vibration due to the resonance with an excitation force generated by the propulsion system. In that case, the installation of dynamic vibration absorber such as Tuned Mass Damper (TMD) on the structure can be considered as an effective alternative countermeasure to reduce the troublesome vibration if structural modification or change of excitation frequencies is difficult. Meanwhile, the conventional optimal design method of TMD premises the target structure exposed on an excitation force without the constraint of its magnitude and frequency range. However, the frequencies of major ship excitation forces due to propulsion system are normally bounded and its magnitude is varied according to its operation speed. Hence, the optimal design of TMD to reduce the resonant vibration of ship local structure should be differently approached compared with the conventional ones. For the purpose, this paper proposes an optimal design method of TMD considering maximum frequency and magnitude variation of a target harmonic excitation component. It is done by both lowering the resonant response at the 1st natural frequency and locating the 2nd natural frequency over maximum excitation frequency for the idealized 2 degree of freedom system consisted of the structure and the TMD. For the validation of the proposed method, a numerical design case of TMD for a ship local structure exposed on resonant vibration due to a propeller excitation force is introduced and its performance is compared with the conventionally designed one.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.174-177
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• 2003

Comparisons of measuring apparatus for sound insulation are made between a reverberation chamber and a simplified test apparatus(APAMAT II) that is used to measure sound insulation performance of inner panels for automobiles. Also, theoretical prediction by using sandwich model are made in order to compare it with experiments and to consequently provide a design tool. Comparative results show that steel ball excitation in APAMAT II has a serious problem with sound insulation performance at the low frequency region, while speaker excitation gives a good agreements with theoretical prediction.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.519-526
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• 2006

This paper compares the seismic response control performance of linear and non-linear models fer tuned liquid damper (TLD). The existing linear and nonlinear TLD models were used for the numerical analysis of single degree of freedom (SDOF) and multi degree of freedom (MDOF) systems with TLD. The nonlinear model considers the variation of the frequency and damping of the TLD with varying excitation amplitude while the linear one has the invariant parameters. Numerical analysis results from SDOF systems indicate that the nonlinear model shows about 5% better control performance than linear one when the mass ratio is 2% and the optimal parameters for reducing peak responses are dependent on the characteristics of the excitation earthquake loads.