• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.2926-2945
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• 2017

In geo-location database oriented spectrum sharing system, the entire geographic area is divided into meshes to classify, store and delivery the cognitive information. In this paper, we propose a flexible polygon mesh division scheme to reduce the number of meshes. Hence the cognitive information can be reduced correspondingly. Besides, polygon mesh can approximate the real environment and reduce the error of cognitive information because the edges of polygon are selected along the boundaries of the networks. We have designed the polygon approximation algorithm and have analyzed the relation between the error and the number of polygon's edges. Finally, the simulation results are provided to verify the algorithm and analysis. The polygon mesh division scheme in this paper provides an efficient approach for cognitive information organization in database oriented spectrum sharing system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.8
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• pp.1894-1912
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• 2012

This paper proposes a system called Wireless Link based on Global Communication Channel (WLGCC) to enhance the spectrum sharing between digital broadcasting (DB) services and the cognitive radio (CR) system in the licensed band of 470-790 MHz. The WLGCC aims to enhance the spectrum sensing and geolocation database (GLD) spectrum sharing methods in the CR system. Spectrum sensing can be enhanced by receiving the status of the used frequencies from the WLGCC, thereby eliminating the need for a low detection threshold (i.e., avoiding the hidden node problem). In addition, the GLD can be enhanced by providing a reliable communication link between the database and the CR device in the form of an unused TV white space that is reserved as the proposed Global Communication Channel (GCC). This paper analyzes the coexistence of the new WLGCC system and the DB service in terms of avoiding additional interference. Specifically, we mathematically determine the WLGCC parameters, such as the in-band and out-of-band power levels, and operation coverage, and verify them using Monte Carlo simulation. The results show that WLGCC does not degrade the existing DB service and reliably transmits information of the vacant (or used) frequency bands to the CR.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.116-119
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• 1999

Amplification factor spectrum, using the observed strong ground motions database in the Korean Peninsula, has been obtained and compared with Standard Response Spectrum, which was suggested by United States Nuclear Regulatory Committee. The observed und motions from the Yongwol and the Kyoungju, and the other recent Earthquakes, respectively, which ate supposed to represent domestic seismotectonic characteristics such as seismic source, attenuation of the propagation medium, and site specific effect, are used for the analysis of amplification factor spectrum. The database are slightly different from the those of the second study. Amplification factors hue been calculated by comparing the observed peak ground motions with results from responses to the observed horizontal na vertical ground motions. The comparison have shown that the amplification factors resultant from this study exceeds these of Standard Response Spectrum, The results suggest that the characteristics of seismic strong ground motion, which are supposed to represent the domestic seismotectonic characteristics, differs from those of Standard Response Spectrum, especially at higher frequencies. The results from the 2nd study are similar to those of 1st analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.57-60
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• 1999

Amplification factor spectrum using the observed strong ground motions database in the Korean Peninsula has been obtained and compared with Standard Rpectrum which wa suggested by United States Nuclear Regulatory Committee. The observed ground motions from the Yongwol and the Kyoungju Earthquakes respectively which are supposed to represent domestic seismotectonic characteristics such as seismic source attenuation of the propagation meium and site specific effect are used for the analysis of amplification factor spectrum,. The database are slightly different from the those of the second study. Amplification factors have been calculated by comparing the observed peak ground motions with results from responses to the observed horizontal na vertical ground motions. The comparison have shown that the amplification factors resultant from this study exceeds those of Standard Response Spectrum The results suggest that the characteristics of seismic strong ground motion which are supposed to represent the domestic seismotectonic characteristics differs from those of Standard Response Spectrum especially at higher frequencies. The results from the 2nd study are similar to those of 1st analysis.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.190-200
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• 2023

As the field of application of in-situ gamma spectroscopy is diversified, proficiency is required for consistent and accurate analysis. In this study, a program was developed to virtually create gamma energy spectra of artificial nuclides, which are difficult to obtain through actual measurements, for training. The virtual spectrum was created by synthesizing the spectra of the background radiation obtained through actual measurement and the theoretical spectra of the artificial radionuclides obtained by a Monte Carlo simulation. Since the theoretical spectrum can only be obtained for a given geometrical structure, representative major geometries for in-situ measurement (ground surface, concrete wall, radioactive waste drum) and the detectors (HPGe, NaI(Tl), LaBr₃(Ce)) were predetermined. Generated virtual spectra were verified in terms of validity and harmonization by gamma spectrometry and energy calibration. As a result, it was confirmed that the energy calibration results including the peaks of the measured spectrum and the peaks of the theoretical spectrum showed differences of less than 1 keV from the actual energies, and that the calculated radioactivity showed a difference within 20% from the actual inputted radioactivity. The verified data were assembled into a database and a program that can generate a virtual spectrum of desired condition was developed.

• Korean Journal of Microbiology
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• v.43 no.2
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• pp.116-123
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• 2007

The purpose of this study was typing the plasmid mediated extended spectrum ${\beta}-lactamases$ produced by enteric bacteria isolated from rivers in Pusan. Six strains of Eschericha coli and fifteen strains of Klebsiella pneumoniae transferred their plasmid mediated extended spectrum ${\beta}-lactamase$ genes to the recipient strain Eschericha coli J53 $Azid^{R}$. The plasmid mediated extended spectrum ${\beta}-lactamase$ genes were sequenced directly after PCR and the types were determined by the BCM Search Launcher and GenBank nucleotid database. Determined types of the plasmid mediated extended spectrum ${\beta}-lactamases$ were TEM-52 and SHV-12. TEM-52 was isolated from both Escherichia coli and Klebsiella pneumoniae. However SHV-12 was isolated from Klebsiella pneumoniae only. The results indicated that the plasmid mediated extended spectrum ${\beta}-lactamase$ producing bacteria spreded over the area of clinical to the nature in Korea.

• Journal of information and communication convergence engineering
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• v.9 no.2
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• pp.166-171
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• 2011

This paper investigates the design issues of spectrum sensing in the cognitive radio (CR) networks of opportunistic unlicensed spectrum access. The cognitive radios can perform a communication using the incumbent user spectrum band without the interference caused by the cognitive radio users. In this case, the cognitive radios must know the real-time radio environments of the incumbent user spectrum band using the spectrum sensing, beacon signal, and geo-location database access. Then in this paper, we are going to provide spectrum sensing issues which include the sensing techniques, the regulatory requirements, the analysis of DTV detection threshold, and main considerations associated with the spectrum sensing design in cognitive radio systems. Also, this paper introduces design trade-offs in order to optimize the sensing parameters such as sensing time and sensing complexity.

• Proceedings of the KSPS conference
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• 2003.05a
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• pp.119-122
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• 2003

In general, triangular shape filters are used in the filter bank when we get the MFCCs from the spectrum of speech signal. In [1], a new feature extraction approach is proposed, which uses specific filter shapes in the filter bank that are obtained from the spectrum of training speech data. In this approach, principal component analysis technique is applied to the spectrum of the training data to get the filter coefficients. In this paper, we carry out speech recognition experiments, using the new approach given in [1], for a large amount of telephone speech data, that is, the telephone speech database of Korean connected digit released by SITEC. Experimental results are discussed with our findings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.779-789
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• 2014

Cognitive radio (CR) technology based on geo-location database access approach and/or wideband spectrum sensing approach is absolutely vital in order to recognize available frequency bands in white spaces (WSs), and efficiently utilize shared spectrums. This paper presents a new structure for the TVWS database access protocol implementation based on Internet Engineering Task Force (IETF) Protocol to Access WS database (PAWS). A wideband compressive spectrum sensing (WCSS) scheme using a modulated wideband converter is also proposed for the TVWS utilization. The developed database access protocol technology which is adopted in both the TV band device (TVBD) and the TVWS database operates well in the TV frequency bands. The proposed WCSS shows a stable performance in false alarm probability irrespective of noise variance estimation error as well as provides signal detection probabilities greater than 95%. This paper also investigates Federal Communications Commision (FCC) regulatory requirements of TVWS database as well as European Telecommunications Standards Institute (ETSI) policy related to TVWS database. A standardized protocol to achieve interoperability among multiple TVBDs and TVWS databases, which is currently prepared in the IETF, is discussed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.88-93
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• 1997

Amplication factor spectrum has been obtained and compared with standard Response Spectrum using the observed strong ground motions database. The observed ground motions from the Miramichi, Nahanni, Saguenay and New Madrid Earthquake (vertical component 19. horizontal component 36). which are estimated to represent domestic seismotectonic characteristics such as seismic source, attenuation, and site effect, are used for the analysis of amplication factor spectrum. Amplication factor has been calculated using both observed peak values and results from responses to the observed horizontal and vertical ground motions. The comparison shows that the amplication factors resultant from this study exceeds those of Standard Response Spectrum at relatively higher frequencies. The results implie that the characteristics of the seismic strong ground motion which may represent the domestic seismotectonic characteristics differs from those of Standard Response Spectrum, which are resultant from the strong ground motions observed mainly at the westem United States.