• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.145-149
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• 1997

This paper describes a methodology for the development of models of discrete event system. The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. This paper proposes a formal structure which can coupled discrete event system models within a framework. The structure employs the discrete event specification formalism for the discrete event system models. The proposed formal structure has been applied to develop a discrete event specification model for the complex spectral density analysis of strip for urin analyzer system. For this, spectral density data of strip is partitioned into a set of Phases based on events identified through urine spectrophotometry. For each phase, a continuous system of the continuous model for the urine spectral density analysis has been simulated by programmed C++. To validate this model, first develop the discrets event specification model, then simulate the model in the DEVSIM++ environment. It has the similar simulation results for the data obtained from the continuous system simulation. The comparison shows that the discrete event specification model represents dynamics of the urine spectral density at each phase.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.10
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• pp.34-40
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• 2001

Ultra Wide Band (UWB) system uses wide band signal, which power spectral density is over all band, It likes as a noise floor, so UWB system can be used without interfering with other communication system. For the first time, we adopted Rayleigh mono pulse antipodal signal which had symmetric characteristic and zero mean. With the power spectral density using stochastic process, we knew that the antipodal signaling scheme removed discrete spectrum and concluded that this had much better spectral suppression, probability of error and data rate than PPM (Pulse Positioning Modulation).

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.187-193
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• 2016

PURPOSE. This pilot study was to find the influence of complete denture on the brain activity and cognitive function of edentulous patients measured through Electroencephalogram (EEG) signals. MATERIALS AND METHODS. The study recruited 20 patients aged from 50 to 60 years requiring complete dentures with inclusion and exclusion criteria. The brain function and cognitive function were analyzed with a mental state questionnaire and a 15-minute analysis of power spectral density of EEG alpha waves. The analysis included edentulous phase and post denture insertion adaptive phase, each done before and after chewing. The results obtained were statistically evaluated. RESULTS. Power Spectral Density (PSD) values increased from edentulous phase to post denture insertion adaption phase. The data were grouped as edentulous phase before chewing (EEG p1-0.0064), edentulous phase after chewing (EEG p2-0.0073), post denture insertion adaptive phase before chewing (EEG p3-0.0077), and post denture insertion adaptive phase after chewing (EEG p4-0.0096). The acquired values were statistically analyzed using paired t-test, which showed statistically significant results (P<.05). CONCLUSION. This pilot study showed functional improvement in brain function of edentulous patients with complete dentures rehabilitation.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1191-1198
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• 2018

The wind profiler radar provides a standing profile of the wind vector and the atmospheric physical signal for the fixed point. Since the wind vector is calculated by the manufacturer's data processing program, the quality control of the date is limited. Therefore, understanding and exploiting the raw spectrum data need to improve the quality of the wind vector. The raw data of the wind vector is the power spectral density stored in binary form. In this study, an algorithm was completed to transform the raw data into the real spectral density, and the use of raw data was evaluated by retrieving zero-order and first-order moments of the spectral based on the spectrum quality control.

• Journal of the Korean Statistical Society
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• v.25 no.2
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• pp.235-241
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• 1996

The ordinary least squares estimator of the disturbance variance in the linear regression model with stationary errors is shown to be asymptotically unbiased when the error process has a spectral density bounded from the above and away from zero. Such error processes cover a broad class of stationary processes, including ARMA processes.

• Journal of the Optical Society of Korea
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• v.12 no.2
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• pp.103-106
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• 2008

It is shown that the two mode representations, one with vector modes and the other with scalar modes, for the cross spectral density matrices of electromagnetic beams are equivalent to each other. In particular, we suggest a method to find the vector modes from the scalar modes and formulate the cross spectral density matrix as a correlation matrix.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.42.2-42.2
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• 2013

The F-GAMMA (FERMI-GST AGN Multi-frequency Monitoring Alliance) project is a program for the monthly monitoring of the broad-band spectra of currently about 90 selected Fermi-GST AGNs. F-GAMMA utilizes several facilities in cm, mm, sub-mm, infrared and optical bands, achieving an unprecedented coverage for the study of the spectral evolution of powerful relativistic jets in AGNs. The KVN joined the F-GAMMA project in May 2011, aiming to monitor flux density at 22 and 43 GHz. We present the preliminary results of flux density variability, evolution of spectral index, and modulation index.

• Communications for Statistical Applications and Methods
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• v.17 no.2
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• pp.223-229
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• 2010

We consider the asymptotic results of the variance ratio statistic when the underlying processes have moving average(MA) unit roots. This degenerate situation of zero spectral density near the origin cause the limit of the variance ratio to become zero. Its asymptotic behaviors are different from non-degenerating case, where the convergence rate of the variance ratio statistic is formally derived.

• Journal of the Korean Ceramic Society
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• v.32 no.7
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• pp.769-776
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• 1995

Infrared radiators of a cordierite system [cordierite (2MgO.2Al2O3.5SiO2)＋30wt% clay＋X wt% MnO2 (X=0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5)] were manufactured by a slurry casting method. Thermal and physical properties of these infrared radiators were studied by the measurement of spectra emissivity, thermal expansion coefficient and apparent density, SEM and EPMA analyses were also carried out. The thermal expansion coefficient and apparent density were decreased with increasing amouonts of MnO2 additives. On the other hand, the spectral emissivity was increased in the wavelength below 4.5${\mu}{\textrm}{m}$. Also, infrared radiators of the cordierite system, of which the spectral emisivity was 0.8, could be attainable in the wavelength above 4.5${\mu}{\textrm}{m}$. The infrared radiator of the cordierite system with 2.0wt% MnO2, of which the spectral emissivity was approximately 1.0, could be attainable in the wavelength between 4.5${\mu}{\textrm}{m}$ and 8${\mu}{\textrm}{m}$. The spectral emissivity of the specimen containing 2.0wt% MnO2 was higher than others in the wavelength between 8${\mu}{\textrm}{m}$ and 14${\mu}{\textrm}{m}$.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.394-404
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• 2013

In the present study, the characteristics of spectral peakedness parameter $Q_p$, bandwidth parameter ${\varepsilon}$, and spectral width parameter ${\nu}$ were analyzed as a first step to define the swell waves quantitatively. For the analysis, the joint probability density function of significant wave heights and peak periods were newly developed. The MCMC(Markov Chain Monte Carlo) simulations have been performed to generate the significant wave heights and peak periods from the developed probability density functions. Applying the simulated significant wave heights and peak periods to the theoretical wave spectrum models, the spectral shapes parameters were obtained and analyzed. Among the spectral shape parameters, only the spectral peakedness parameter $Q_p$, is shown to be independent with the significant wave height and peak wave period. It also best represents the peakedness of the spectral shape, and henceforth $Q_p$ should be used to define the swell waves with a wave period. For the field verification of the results, wave data obtained from Hupo port and Ulleungdo were analyzed and results showed the same trend with the MCMC simulation results.