• Structural Engineering and Mechanics
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• 제71권6호
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• pp.683-697
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• 2019

The reinforced concrete (RC) structures usually suffer large residual displacements under strong motions. The large residual displacements may substantially reduce the anti-seismic capacity of structures during the aftershock and increase the difficulty and cost of structural repair after an earthquake. To reduce the adverse residual displacement, several self-centering energy dissipation braces (SCEBs) have been proposed to be installed to the RC structures. To investigate the seismic responses of the RC structures with SCEBs under the earthquake excitation, an extended Bouc-Wen model with degradation and self-centering effects is developed in this study. The extended model realized by MATLAB/Simulink program is able to capture the hysteretic characteristics of the RC structures with SCEBs, such as the energy dissipation and the degradation, especially the self-centering effect. The predicted hysteretic behavior of the RC structures with SCEBs based on the extended model, which used the unscented Kalman filter (UKF) for parameter identification, is compared with the experimental results. Comparison results show that the predicted hysteretic curves can be in good agreement with the experimental results. The nonlinear dynamic analyses using the extended model are then carried out to explore the seismic performance of the RC structures with SCEBs. The analysis results demonstrate that the SCEB can effectively reduce the residual displacements of the RC structures, but slightly increase the acceleration.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.465-472
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• 2001

This paper describes the characteristics of wind induced noise from high-voltage overhead transmission facilities which include transmission lines. insulator strings. and aviation beacon spheres installed on the overhead ground wires. High-voltage overhead transmission lines generate an audible wind noise due to the alternate shedding of wind-induced vortices. The frequency spectrum from the insulator strings reveals its resonance peak. This resonance sound mechanism has been supposed the self-excitation phenomenon of the resonance and the velocity fluctuation. The booming noises from the aviation beacon spheres are detected and analysed.

• Smart Structures and Systems
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• 제20권3호
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• pp.285-301
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• 2017

This paper presents the design and the application of a new self-powered hybrid electromagnetic damper that can harvest energy while mitigating the vibration of a structure. The damper is able to switch between an energy harvesting passive mode and a semi-active mode depending on the amount of energy harvested and stored in the battery. The energy harvested in the passive mode resulting from the suppression of vibration is employed to power up the monitoring and electronic components necessary for the semi-active control. This provides a hybrid control capability that is autonomous in terms of its power requirement. The proposed hybrid circuit design provides two possible options for the semi-active control: without energy harvesting and with energy harvesting. The device mechanism and the circuitry that can drive this self-powered electromagnetic damper are described in this paper. The parameters that determine the device feasible force-velocity region are identified and discussed. The effectiveness of this hybrid damper is evaluated through a numerical simulation study on vibration mitigation of a bridge stay cable under wind excitation. It is demonstrated that the proposed hybrid design outperforms the passive case without external power supply. It is also shown that a broader force range, facilitated by decoupled passive and semi-active modes, can improve the vibration performance of the cable.

• 전기학회논문지P
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• 제51권2호
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• pp.60-67
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• 2002

This paper presents a control approach for designing a self tuning fuzzy controller for a synchronous generator excitation and SVC system. A combination of thyristor-controlled reactors and fixed capacitors (TCR-FC) type SVC is recognized as having the most flexible control and high speed response, which has been widely utilized in power systems, is considered and designed to improve the response of a synchronous generator, as well as controlling the system voltage. The proposed parameter self tuning algorithm of fuzzy controller is based on the steepest decent method using two direction vectors which make error between inference values of fuzzy controller and output values of the specially selected PSS reduce steepestly. Using input-output data pair obtained from PSS, the parameters in antecedent part and in consequent part of fuzzy inference rules are learned and tuned automatically using the proposed steepest decent method. The related simulation results show that the proposed fuzzy controller is more powerful than the conventional ones.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2268-2275
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• 2018

This paper presents a high-efficiency low-power permanent magnet (PM) generator for the power supply of the generator exciter. In the conventional generator system, the power for the exciter is fed by the generator output power or an emergency battery for the starting. The proposed low-power PM generator can generate the proper power and voltage to excite the exciter field winding. According to the starting of the generator, the designed PM generator can supply the constant voltage to the Automatic Voltage Regulator (AVR), then it can be used to control of exciter field current for the generator. Because of the designed PM generator which is placed inside the conventional generator system, the emergency battery and Potential Transducer(PT) for AVR can be removed. Thus, the total efficiency can be improved. The proposed generator system is tested in the practical system. And the efficiency characteristic is analyzed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.867-869
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• 2000

This paper describes the steady state performance of a self-excited wound type induction generator with stator and rotor windings connected in series along with excitation capacitors. For this purpose a mathematical model is developed by means of the well known generalized machine theory utilizing d-q axis orthogonal transformation. This model can be used to analyze short shunt and long shunt generators as well as shunt generator and the algorithm for this analysis is persented. The characteristics of generators are compared one another by using parameters which are validated by Mostafa et al.

• 셀메드
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• 제13권2호
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• pp.1.1-1.5
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• 2023

The purpose of this study is to propose a role as healing music through Hoesimgok's interaction. The song "Hoesimgok (悔心曲, 回心曲, Regretting Song)" means a song that expresses regret. There's nothing more desperate than my parents in a song of regret. Your heart for your late parents must be the thing you regret the most. We always think that we should be filial to my parents, but we can't. We are under a lot of stress due to situations and environments that are unintentionally not filial. Audiences who show self-reflection on their filial piety become emotional identities with those who sing with the lyrics and actions of songs and music. Therefore, Hoesimgok is a song and a prayer. Music exerts a range of powerful biological effects beyond nice sound and furthermore, it is expanding to music therapy. It can also bring about peace of mind by regulating sympathetic nervous system excitation. Our results suggest that Hoesimgok can have the effect of making listeners as well as singers happy.

• 대한기계학회논문집B
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• 제34권4호
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• pp.399-408
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• 2010

질소 희석된 프로판 층류 부상 화염에서 화염진동 불안정성과 화염 곡률 효과를 살펴보기 위하여 실험적 연구를 수행하였다. 화염 진동은 총 3가지 영역으로 열손실에 의한 진동, 열손실 및 부력이 혼재된 진동, 그리고 열손실 및 루이스 수에 의한 영향이 혼재된 진동으로 구분되었다. 순수 열손실에 의한 진동은 루이스 수에 의한 진동과 부력에 의한 수력학적 불안정성과 관련이 없으며 연료 루이스 수에 관계없이 모든 부상화염 조건에서 관찰되었다. 화염의 시간에 따른 부상높이 변화에 대한 FFT분석을 통해 화염진동 불안정성의 실험적 증거와 특성을 명확히 제시하였고, 부상 화염의 열손실에 의한 자기진동의 메커니즘에 대한 시나리오를 논의한다.

• 한국연소학회지
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• 제19권2호
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• pp.8-14
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• 2014

Experiments were conducted to clarify role of the outermost edge flame on low-strain-rate flame extinction in buoyancy-suppressed non-premixed methane flames diluted with He and $N_2$. The use of He curtain flow produced a microgravity level of $10^{-2}-10^{-3}g$ in $N_2$- and He-diluted non-premixed counterflow flame experiments. The critical He and $N_2$ mole fractions at extinction with a global strain rate were examined at various burner diameters (10, 20, and 25 mm). The results showed that the extinction curves differed appreciably with burner diameter. Before the turning point along the extinction curve, low-strain-rate flames were extinguished via shrinkage of the outermost edge flame with and without self-excitation. High-strain-rate flames were extinguished via a flame hole while the outermost edge flame was stationary. These characteristics could be identified by the behavior of the outermost edge flame. The results also showed that the outermost edge flame was not influenced by radiative heat loss but by convective heat addition and conductive heat losses to the ambient He curtain flow. The numerical results were discussed in detail. The self-excitation before the extinction of a low-strain-rate flame was well described by a dependency of the Strouhal number on global strain rate and normalized nozzle exit velocity.

• 한국진공학회지
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• 제15권3호
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• pp.308-313
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• 2006

서로 다른 성장조건 하에서 자발형성 InAs 양자점 (quantum dot, QD)을 제작하고. 그 특성을 photoluminescence (PL) 로 분석하였다. 비교적 높은 기판온도에서 성장된 QD 시료들의 PL 스펙트럼에서 분명한 차이를 나타내는 double-peak이 관측되었다. 온도 및 여기광 출력의존성 (temperature- and excitation power dependence) PL을 이용하여 그 double-peak이 서로 다른 크기분포를 가지는 두개의 InAs QD집단에서의 기저발광 (Eo) 에 의한 peak 임을 알 수 있었다. 게다가 이중크기분포에서 InAs 두께변화는 서로 대립되는 두 QD집단에서 QD 수의 변화를 초래한다는 것 또한 증명하였다.