• Title/Summary/Keyword: Frequency drift

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Wind Induced Vibration Design for High-rise buildings through Control of Natural Period (주기 조절을 이용한 고층 건물의 풍응답 조절 설계)

  • 김지은;차성희;서지현;박효선
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.10a
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    • pp.43-51
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    • 2004
  • As the slenderness ratio of a high-rise building increases, the lateral load resisting system for the building is more often determined by serviceability design criteria. In serviceability design, the maximum drift and the level of vibration are controlled not to exceed the design criteria. Even though many drift method have been developed in various forms, no practical design method for wind induced vibration has been developed so far. Structural engineers rely upon heuristic or experience in designing wind induced vibration. Development of practical design method for wind induced vibration is required. Generally, wind induced acceleration responses are depending on several variables such as the weight density of a building, damping ratio, the natural period, and etc.. All parameters except the natural period or frequency are usually out of reach for structural engineers, then the wind acceleration response may be proportioned to the natural period. Therefore, in this paper, a wind induced vibration design method based on frequency control technique for high-rise is proposed. The method is applied to vibration design of a 25-story office building for performance evaluation.

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Analysis on the dynamic characteristics of RAC frame structures

  • Wang, Changqing;Xiao, Jianzhuang
    • Structural Engineering and Mechanics
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    • v.64 no.4
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    • pp.461-472
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    • 2017
  • The dynamic tests of recycled aggregate concrete (RAC) are carried out, the rate-dependent mechanical models of RAC are proposed. The dynamic mechanical behaviors of RAC frame structure are investigated by adopting the numerical simulation method of the finite element. It is indicated that the lateral stiffness and the hysteresis loops of RAC frame structure obtained from the numerical simulation agree well with the test results, more so for the numerical simulation which is considered the strain rate effect than for the numerical simulation with strain rate excluded. The natural vibration frequency and the lateral stiffness increase with the increase of the strain rate. The dynamic model of the lateral stiffness is proposed, which is reasonably applied to describe the effect of the strain rate on the lateral stiffness of RAC frame structure. The effect of the strain rate on the structural deformation and capacity of RAC is analyzed. The analyses show that the inter-story drift decreases with the increase of the strain rate. However, with the increasing strain rate, the structural capacity increases. The dynamic models of the base shear coefficient and the overturning moment of RAC frame structure are developed. The dynamic models are important and can be used to evaluate the strength deterioration of RAC structure under dynamic loading.

Novel islanding detection method for grid connected PV system (계통연계형 태양광발전시스템의 새로운 단독운전 검출기법)

  • Jung, Young-Seok;So, Jung-Hun;Yu, Byung-Gyu;Yu, Gwon-Jong;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • 2005.07b
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    • pp.1705-1707
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    • 2005
  • This paper proposes a novel active frequency drift(AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic(PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction(cf) enables the islanding detection to drift up(or down) the frequency of the voltage during the islanding situation. However, the performance of the conventional AFD methods, which have a certain value of cf only, is inefficient and difficult to design the appropriate cf value analytically to meet the limit of harmonics. In this paper, the periodic chopping fraction based on an AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 929-2000 with the power quality and islanding detection time. To verify the validation of the proposed method, the islanding test results are presented. It is confirmed that the proposed method has not only less harmonic distortion but also good performance of islanding detection compare with the conventional AFD method.

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Hartley-VCO Using Linear OTA-based Active Inductor

  • Jeong, Seong-Ryeol;Chung, Won-Sup
    • Journal of IKEEE
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    • v.19 no.4
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    • pp.465-471
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    • 2015
  • An LC-tuned sinusoidal voltage-controlled oscillator (VCO) using temperature-stable linear operational transconductance amplifiers (OTAs) is presented. Its architecture is based on Hartley oscillator configuration, where the inductor is active one realized with two OTAs and a grounded capacitor. Two diode limiters are used for limiting amplitude. A prototype oscillator built with discrete components exhibits less than 3.1% nonlinearity in its current-to-frequency transfer characteristic from 1.99 MHz to 39.14 MHz and $220ppm/^{\circ}C$ frequency stability to the temperature drift over 0 to $75^{\circ}C$. The total harmonic distortion (THD) is as low as 4.4 % for a specified frequency-tuning range. The simulated phase noise of the VCO is about -108.9 dBc/Hz at 1 MHz offset frequency in frequency range of 0.4 - 46.97 MHz and property of phase noise of VCO is better than colpitts-VCO.

A study on characteristics of piezo-buzzer for pressure sensor (압력센서용 압전부저의 특성에 관한 연구)

  • 신영록;김홍근;김철한;최헌일;사공건
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.985-988
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    • 2001
  • A piezo-buzzer being used for the purpose of generation of audible frequency, which is a electric-acoustic transducer utilizing the inverse piezoelectric effect. Also it can be used for a pressure sensor according to the piezoelectric effect. But the output of a piezo-buzzer is a differential signal. In this study, we've made a system that can measure a real pressure by integration of output signal. According to our results, it could be found a possibility of application for pressure sensor by measurement of output characteristics when a piezo-buzzer was pressurized and depressurized, and by measuring of an error by means of the drift current of OP-Amp, etc..

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Analysis of Electron Transport in InAlAs/InGaAs HBT by Hybride Monte Carlo Simulation (Hybrid Monte Carlo 시뮬레이션에 의한 InAlAs/InGaAs HBT의 전자전송 해석)

  • 송정근;황성범;이경락
    • Electrical & Electronic Materials
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    • v.10 no.9
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    • pp.922-929
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    • 1997
  • As the size of semiconductor devices shrinks in the horizontal as well as vertical dimension it is difficult to estimate the transport-velocity of electron because they drift in non-equilibrium with a few scattering. In this paper HYbrid Monte Carlo simulator which employs the drift-diffusion model for hole-transport and Monte Carlo model for electron-transport in order to reduce the simulation time and increase the accuracy as well has been developed and applied to analyze the electron-transport in InAlAs/InGaAs HBT which is attractive for an ultra high speed active device in high speed optical fiber transmission systems in terms of the velocity and energy distribution as well as cutoff frequency.

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Nonlinear Response Analyses for a Barge-Mounted Plant with Dolphin Mooring Systems in Irregular Waves (불규칙파 중에서 돌핀 계류된 바아지식 해상공장에 대한 비선형 응답 해석)

  • 이호영;신현경;염재선
    • Journal of Ocean Engineering and Technology
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    • v.14 no.4
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    • pp.1-8
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    • 2000
  • The time simulation of motion responses of dolphin-moored BMP in waves is presented. The equation of motion based on Cummin's theory of impulse responses are employed, and solved in time domain by using the Newmark $\beta$ method. The hydrodynamic coefficient and first order wave exciting forces involved in the equations are obtained from a three-dimensional panel method in the frequency domain. The second order wave drift forces and mooring for dolphin system are taken into account. As for numerical example, time domain analysis are carried out for a BMP in irregular wave condition.

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Dynamic and Stochastic Modeling of Litten´s space Inertial Reference Unit(SIRU)

  • Park, H.T.;K.Y Yong;B.S. Suk
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.167.4-167
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    • 2001
  • Accurate mathematical models of spacecraft components are an essential of spacecraft attitude control system design, analysis and simulation. Gyro is one of the most important spacecraft components used for attitude propagation and control. Gyro errors may seriously degrade the accuracy of the calculated spacecraft angular rate and of attitude estimates due to inherent drift and bias errors. In this paper, a detailed mathematical model of gyro containing the relationships for predicting spacecraft angular rate and disturbances is proposed. Stochastic model describing random drift behavior is discussed in frequency domain and time domain. In order to illustrate this approach, we analyze the behavior for Litton´s Space Inertial Reference Uint(SIRU).

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Removing Baseline Drift from ECG Signal Using Smoothing Spline and Morphology Operation (평활화 스플라인 연산과 형태학 연산을 이용한 기저선 변동 잡음 제거)

  • Back, Seung-Gwan;Choi, Chang-Hoon;Kim, Jeong-Hong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.1
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    • pp.162-171
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    • 2017
  • Low frequency noise components causes the baseline drift in the ECG signals. In this paper, a morphological operation and smoothing spline technique are used for ECG signal processing in order to accomplish baseline correction. Removing the baseline drift from ECG signal using morphology operation, the feature of original signal may be distorted. To resolve this distortion problem, we applied a smoothing spline operation after morphology operation. In order to compare with existing morphology operation method for baseline correction, we apply proposed method to ECG data in MIT/BIH database. Compared to other existing method, our proposed method achieved low data distortion on the original signal.

Comparison of AT1- and Kalman Filter-Based Ensemble Time Scale Algorithms

  • Lee, Ho Seong;Kwon, Taeg Yong;Lee, Young Kyu;Yang, Sung-hoon;Yu, Dai-Hyuk;Park, Sang Eon;Heo, Myoung-Sun
    • Journal of Positioning, Navigation, and Timing
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    • v.10 no.3
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    • pp.197-206
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    • 2021
  • We compared two typical ensemble time scale algorithms; AT1 and Kalman filter. Four commercial atomic clocks composed of two hydrogen masers and two cesium atomic clocks provided measurement data to the algorithms. The allocation of relative weights to the clocks is important to generate a stable ensemble time. A 30 day-average-weight model, which was obtained from the average Allan variance of each clock, was applied to the AT1 algorithm. For the reduced Kalman filter (Kred) algorithm, we gave the same weights to the two hydrogen masers. We also compared the frequency stabilities of the outcome from the algorithms when the frequency offsets and/or the frequency drift offsets estimated by the algorithms were corrected or not corrected by the KRISS-made primary frequency standard, KRISS-F1. We found that the Kred algorithm is more effective to generate a stable ensemble time scale in the long-term, and the algorithm also generates much enhanced short-term stability when the frequency offset is used for the calculation of the Allan deviation instead of the phase offset.