• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.7
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• pp.265-272
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• 2006

This paper describes a method of parameter estimation of time series data using discrete Fourier transform(DFT). DFT have been mainly used to precisely and rapidly obtain the frequency of a signal. In a dynamic system, a real part of a mode used to learn damping characteristics is a more important factor than the frequency of the mode. The parameter estimation method of this paper can directly estimate modes and parameters, indicating the characteristics of a dynamic system, on the basis of the Fourier transform of the time series data. Real part of a mode estimates by subtracting a frequency of the Fourier spectrum corresponding to 0.707 of a magnitude of the peak spectrum from a peak frequency, or subtracting a frequency of the power spectrum corresponding to 0.5 of the peak power spectrum from a peak frequency, or comparing the Fourier(power) spectrum ratio. Also, the residue and phase of time signal calculate by simple equation with the real part of the mode and the power spectrum that have been calculated. Accordingly, the proposed algorithm is advantageous in that it can estimate parameters of the system through a single DFT without repeatedly calculating a DFT, thus shortening the time required to estimate the parameters.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.1
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• pp.69-75
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• 2023

In Korea, most nuclear power plants were designed based on the design response spectrum of Regulatory Guide 1.60 of the NRC. However, in the case of earthquakes occurring in the country, the characteristics of seismic motions in Korea and the design response spectrum differed. The seismic motion in Korea had a higher spectral acceleration in the high-frequency range compared to the design response spectrum. The seismic capacity may be reduced when evaluating the seismic performance of the equipment with high-frequency earthquakes compared with what is evaluated by the design response spectrum for the equipment with a high natural frequency. Therefore, EPRI proposed the inelastic energy absorption factor for the equipment anchorage. In this study, the seismic performance of welding anchorage was evaluated by considering domestic seismic characteristics and EPRI's inelastic energy absorption factor. In order to reflect the characteristics of domestic earthquakes, the uniform hazard response spectrum (UHRS) of Uljin was used. Moreover, the seismic performance of the equipment was evaluated with a design response spectrum of R.G.1.60 and a uniform hazard response spectrum (UHRS) as seismic inputs. As a result, it was confirmed that the seismic performance of the weld anchorage could be increased when the inelastic energy absorption factor is used. Also, a comparative analysis was performed on the seismic capacity of the anchorage of equipment by the welding and the extended bolt.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.267-272
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• 2014

In this paper, we analyze the characteristics for the driving shock resistance of the military vehicle through the bump test. Prior to the experiment, theoretical analysis was performed by using the SRS(shock response spectrum) and VRS(vibration response spectrum) analysis method. And we estimated the characteristics for the driving shock resistance of the military vehicle. Bump test was performed using the acceleration sensor and the driving test at a different speed. We evaluated the characteristics for the driving shock resistance of the military vehicle based on the result. And predicted values were compared with the theoretical analysis. In addition, we evaluated the results of the theoretical prediction of the SRS and the VRS analysis. And we evaluate the suitability of the prediction method at military vehicle shock analysis.

• Speech Sciences
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• v.12 no.4
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• pp.43-52
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• 2005

The common form of pre-emphasis filter is $H(z)\;=\;1\;- az^{-1}$, where a typically lies between 0.9 and 1.0 in voiced signal. Also, this value reflects the degree of filter and equals R(1)/R(0) in Auto-correlation method. This paper proposes a new flattening algorithm to compensate the weaked high frequency components that occur by vocal cord characteristic. We used interval information of LSP to estimate formant frequency. After obtaining the value of slope and inverse slope using linear interpolation among formant frequency, flattening process is followed. Experimental results show that the proposed algorithm flattened the weaked high frequency components effectively. That is, we could improve the flattened characteristics by using interval information of LSP as flattening factor at the process that compensates weaked high frequency components.

• Journal of Biosystems Engineering
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• v.29 no.4
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• pp.329-334
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• 2004

This study was conducted to investigate the characteristics of transmittance spectrum of Korean red ginseng using VIS/NIR spectroscopy. The results of this study were as follows; Light intensity affected the characteristics of the spectrum. For over 40% light intensity, the first and second peaks appeared at 700nm and 1,100nm, respectively. For the 20% light intensity, the first and second peaks appeared at 800nm and 1,100nm, respectively. Thus, the typical color characteristics of halogen lamp were similar to each other if over 40% of maximum light intensity power, otherwise it was not. Transmittance spectrum showed different characteristics at different portions of red ginseng. Normal red ginseng showed strong intensity at the first peak around 700nmbecause of reddish internal tissue. However, an internal white core red ginseng showed weak peak-intensity due to whitish internal tissue. There was no significant difference in the second peak at 800nm for the different internal qualities. Third peak at 900nm showed somewhat difference by internal qualities but it was difficult to find significant trend. To separate the differences of the internal qualities, intensity differences between peaks were used. It was possible to classify normal red ginseng by the differences of "peak 1 -peak 2" and "peak 1 - peak 3". In addition, shift of the first and the third peaks in the spectrum could separate normal red ginseng from others.ginseng from others.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.367-374
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• 2000

This study investigates the effect of hysteretic characteristics to the Inelastic Demand Spectrum (IDS) which was expressed by an acceleration(Sa) and a displacement response spectrum (Sd). Elasto Perfectly Plastic(EPP) model is used in this study and inelastic demand spectrum (Sa vs, Sd) are obtained from a given target ductility ratio. For a given target ductility ratio IDS can be obtained by using nonlinear time history analysis of single degree of system with forth five recorded earthquake ground motions for stiff soil site. The effect EPP model under demand spectrum is investigated by ductility factor and natural frequency. According to the results obtained in this study IDS has dependency on ductility factor and natural frequency.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.273-274
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• 2002

In order to evaluate the flying characteristics of slider, the acoustic emission (AE) as well as friction signals are typically utilized. In this work the frequency spectrum analysis is performed using the AE signal obtained during the head/disk interaction such as load/unload mechanism using ramp, impact situation in the presence of a bump on disk surface and other contact phenomena including particle interaction. It was shown that the influence of impact can be characterized effectively in the AE frequency spectrum. As a result of this work, frequency spectrum analysis will be utilized with better understanding for studying the head/disk interface (HDI) characteristics and monitoring the particle interaction in HDI effectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.3
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• pp.45-57
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• 1995

We derive analytic expressions for the spontaneous emission spectrum of a device using DFB structures including the effects of both facet reflections and the phase of a grating. In solution of coupled mode equations. Equations for the reations between the spontaneous emission spectrum and structure parameters of the device are derived to investigate the effect of structure parameters on the spontaneous emission spectrum and operating characteristics of possibility of evaluating the structure parameters of the device from its spontaneous emission spectrum.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.433-438
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• 2001

The response spectrum has been widely used to differentiate the significant characteristics of earthquake ground motion and to evaluate the response of structures under ground shaking. Current design response spectrum is based on Seed, Ugas, and Lysmer's study. (1976) In this study, earthquake ground motion data sets adopted by Seed, Miranda, and Riddell is analyzed regards to soil types. And how earthquake data sets effected the design response spectrum is evaluated using acceleration-displacement response spectrum.

• Proceedings of the Technology Innovation Conference
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• 2004.02a
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• pp.108-131
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• 2004

Having the characteristics of public goods, Radio Spectrum had been controlled by Government Authorities. In the past, technological side of spectrum, such as cross protection, was the main concern, but as the telecommunication industry is developing gradually, economic side of spectrum is becoming an important part. To uplift the Economic efficiency of spectrum management policy, clarifying the basic value of spectrum is one of the most important things. Also, both government authorities and spectrum licensees will have to choose license or investment under uncertainties such as license timing, time to market, technology standard, and so on. Considering all things, this paper gives the value to the spectrum by real options theory, which is a powerful method concerning uncertainty, especially for government, And we applied it to a specific spectrum band for the portable Internet in Korea. These results can provide information about the technological standard, optimal market-entry time as well as the value of spectrum for the portable Internet.