• International Journal of Aeronautical and Space Sciences
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• 제13권4호
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• pp.499-506
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• 2012

In this paper, a dynamic modeling for the velocity and position information of a single frequency stand-alone GPS(Global Positioning System) receiver is described. In static condition, the position error dynamic model is identified as a first/second order transfer function, and the velocity error model is identified as a band-limited Gaussian white noise via non-parametric method of a PSD(Power Spectrum Density) estimation in continuous time domain. A Kalman filter is proposed considering both correlated/white measurements noise based on identified GPS error model. The performance of the proposed Kalman filtering method is verified via numerical simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제15권7호
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• pp.878-884
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• 2005

This paper presents an algorithm for the precision motion control based on the dynamic characteristics of piezoelectric actuators in the inchworm. The dynamic characteristics are identified by the frequency domain modeling technique using the experimental data. For the motion control, the hysteresis behavior is compensated by the inverse hysteresis model. The dynamic stiffness of an inchworm is generally low compared to its driving condition, so mechanical vibration may degenerate the motion accuracy of the inchworm. The Sliding mode controller and the Kalman filter are designed for motion control of the inch-worm.

• Journal of Communications and Networks
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• 제15권6호
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• pp.547-558
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• 2013

Ultra broadband communication systems operated at THz frequencies will require the thorough knowledge of the propagation channel. Therefore, an extensive measurement campaign of 50 GHz wide indoor radio channels is presented for the frequencies between 275 and 325 GHz. Individual ray paths are resolved spatially according to angle of arrival and departure. A MIMO channel is recorded in a $2{\times}2$ configuration. An advanced frequency domain ray tracing approach is used to deterministically simulate the THz indoor propagation channel. The ray tracing results are validated with the measurement data. Moreover, the measurements are utilized for the calibration of the ray tracing algorithm. Resulting ray tracing accuracies are discussed.

• The Transactions of the Korean Institute of Power Electronics
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• 제25권6호
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• pp.477-483
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• 2020

This study proposes a DQ synchronous reference frame model of a series-parallel tuned inductive power transfer (SP-IPT) system. The wireless power transmission system experiences control difficulty because the transmitter-side controller cannot directly measure the receiver-side load voltages and currents. Therefore, a control-oriented circuit model that shows the dynamics of the IPT system is required to achieve a well-behaved controller. In this study, an equivalent circuit model of the SP-IPT system in a synchronously rotating reference frame is proposed using the single-phase DQ transformation technique. The proposed circuit model is helpful in modeling the dynamics of the voltages and currents of the transmitter- and receiver-side resonant tanks and loads. The proposed circuit model is evaluated using frequency- and time-domain simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제24권5호
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• pp.558-565
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• 2013

In this paper, modeling and simulation for performance analysis of high resolution SAR system has been carried out in the time, frequency and numeric domain using ADS Ptolemy simulation tool of Agilent corporation. SAR system consists of antenna, controller and transceiver. Error parameters affecting SAR system performances have been defined, modeled and simulated such as phase noise of frequency synthesizer, amplitude and phase characteristic of TWTA, sampling frequency of waveform generator and I/Q imbalance. Finally, the development requirements of SAR system based on the impulse response function have been derived.

• Journal of the Earthquake Engineering Society of Korea
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• 제19권1호
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• pp.1-11
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• 2015

In order to perform a soil-isolation-structure interaction analysis of seismically isolated nuclear power plant (NPP) structures, the nonlinear behavior of a seismic isolation system may be converted to an equivalent linear model used in frequency domain analysis. Seismic responses for seismically isolated NPP containment structures subjected to a simple artificial acceleration history and different site class earthquakes are evaluated for the equivalent-linear and nonlinear models that have been applied to lead-rubber bearing (LRB) modeling. It can be observed that the maximum displacements of the equivalent linear model are larger than that of the nonlinear model. From the floor response spectrum analysis for the top of NPP containment structures, it can be observed that the spectral acceleration of an equivalent linear model at about 0.5 Hz frequency is about 2~3 times larger than that of a nonlinear model.

• The Journal of the Acoustical Society of Korea
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• 제26권7호
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• pp.328-333
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• 2007

In this paper, we describe characteristics of a movable bridge called the Anjok and propose an improved string model which has delay line controller in physical modeling of the Gayageum. Movable bridge, the Anjok determines the length of vibrating string and transmits the vibration of each string to the body of the Gayageum. We analyze the variations in frequency domain and implement the Anjok model as parametric form using the first-order polynomial fitting in logarithmic scale graph, because the length of string changes fundamental frequency. In order to implement the Anjok model, frequency fitting, tension fitting and frequency fitting using leaky integrator are used. The frequency fitting using leaky integrator has the best results among those. Proposed string model with the Anjok model can represent real tuning system of the real Gayageum and the proposed model could synthesize sounds which is similar to original sounds.

• Journal of Communications and Networks
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• 제5권4호
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• pp.319-327
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• 2003

We consider the problem of low-sampling rate high-resolution channel estimation and timing for digital ultrawideband (UWB) receivers. We extend some of our recent results in sampling of certain classes of parametric non-bandlimited signals and develop a frequency domain method for channel estimation and synchronization in ultra-wideband systems, which uses sub-Nyquist uniform sampling and well-studied computational procedures. In particular, the proposed method can be used for identification of more realistic channel models, where different propagation paths undergo different frequency-selective fading. Moreover, we show that it is possible to obtain high-resolution estimates of all relevant channel parameters by sampling a received signal below the traditional Nyquist rate. Our approach leads to faster acquisition compared to current digital solutions, allows for slower A/D converters, and potentially reduces power consumption of digital UWB receivers significantly.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.221-224
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• 2001

In this paper, the bonding wire interconnection has been studied from the points of view of modeling and electrical characterization. The bonding wire is measured by TDR(Time Domain Reflectometry) and Network analyzer(1-10㎓). First, one gold bonding wire mounted on 2mm gap substrate measured 3.68nH by TDR and 3.39nH by Network analyzer(6㎓). Two gold bonding wire mounted on 2mm gap substrate measured 3.14nH by TDR and 2.80nH by Network analyzer. This result presented that inductance of bonding wire could be employed as inductors for radio frequency circuit packaging.

• Proceedings of the KSR Conference
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.344-349
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• 2005

The axially moving thin beam-plates exposed to sudden thermal loadings may experience severe vibrations through the thermal shock process. For accurate prediction of the thermal shock-induced vibrations, this paper develops a spectral element model for axially moving thermoelastic beam-plates. The spectral element model which is represented by spectral element matrix is formulated from the frequency-dependent dynamic shape functions which satisfy the governing equations in the frequency-domain. Thus, when compared with the classical finite element model in which simple polynomial functions are used as the shape functions, the spectral element model can provide exact solution by treating a whole uniform structure member as a single finite element, regardless of its length.