• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.10-16
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• 1996

In this paper, we have analyzed the error performance of the optimum threshold detection(OTD) of 16 QAM signal in the Rician fading channel with and without the maximal ratio combining(MRC) diversity technique in the presence of cochannel Rayleigh interference. An also the error performance of OTD is compared to that of conventional threshold detection(CTD) in the Rician fading channel in the presence of cochannel Rayleigh interference. With the result of analysis, it is found that there exists a synergistic effect due to both MRC diversity and optimum threshold detection in the Rician fading channel in the presence of cochannel Rayleigh interference.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.243-249
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• 2010

In this thesis, in order to a equivalent circuit-analytical study for a symmetric double gate type MOSFET, we slove analytically the 2D Poisson's equation in a a silicon body. To solve the threshold voltage in a symmetric double gate type MOSFET from the derived expression for the surface potential which the two-dimensional potential distribution of a symmetric double gate type MOSFET is assumed approximately. This thesis can use short and long channel in a silicon body we introduce a new the threshold voltage model in a symmetric double gate type MOSFET and measure it the distance about the range of channel length up to 0.1 [${\mu}m$].

• Journal of Advanced Navigation Technology
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• v.6 no.3
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• pp.231-240
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• 2002

For a long time target maneuvers in tracking problem have been a difficult task to handle. In order to solve this problems. there have been various tracking techniques. In the development of a tracking filter for a maneuvering target, maneuver detection threshold plays a key role. However, no study of filter performance the varying maneuver detection threshold has been carried out so far. Instead, the maneuver detection have been chosen empirically. In this paper, the effect of detection threshold selection on the performance of the tracking filters was considered and the relationships between maneuvers and the detection threshold have been analyzed by simulation.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.109-118
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• 2001

KITSAT-1, launched in 1992, passes through Inner Van Allen Radiation Belt in which high energy Protons cause single event upsets(SBUs) in the main memory of KITSAT-1 OBC(On-Board Computer) 186. The present paper compares SEU data from the OBC186 with the AP-8 model of NASA/NSSDC using the Chi-Square method to estimate the SEU threshold energy. Shielding effect by the satellite body has been taken into account to model the proton fluxes at the position of OBC186, and SEUs recorded during the high solar activities have been removed to avoid the spurious result. The result shows that the SEU threshold energy of the main memory of KITSAT-1 OBC186 is estimated to be about $110{pm}10MeV$.

• Biomedical Science Letters
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• v.20 no.4
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• pp.201-208
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• 2014

This study was conducted to investigate hypoacusis due to workplace noise among dental technicians. Pure tone audiometry, impedance audiometry and heart rate variability were measured for 60 dental technicians and office workers in D city from July to November 2013, and a survey on the effects of noise was conducted. SPSS 19.0 was used for statistical analysis. In the result for threshold of pure tone audiometry, the average hearing threshold of left ears in the air conduction (AC) test showed a statistically significant decrease (P=0.019) among dental technicians, who are frequently exposed to workplace noise. The hearing threshold in the AC test for each frequency was significantly different between the two groups at 125 Hz (P=0.012) in right ears and at 1 kHz (P=0.022), 2 kHz (P=0.040), and 8 kHz (P=0.018) in left ears. Dental technicians who had worked for 16 years or longer had a significantly higher incidence of hypoacusis in the right ear (P=0.030) and in the left ear (P=0.010). In impedance audiometry showed a tympanometry result of type A in both the dental technician group and the office worker group.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.119-125
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• 2009

This paper deals with the characteristics of soil ionization affecting the dynamic performance of grounding systems under lightning impulse voltage. A concentric hemispherical electrode system was employed in order to facilitate the field calculation and analysis of the experimental results. The parameters such as the ionization threshold and breakdown field intensity, the pre-ionization and the post ionization resistances, the time-lag to ionization, the transient impedance, the equivalent ionized radius for various soil media were measured and analyzed. The dynamic characteristics of ionization processes under lightning impulse voltage are strongly dependent on the types of soil and water content. As a result, a soil ionization reduces the ground resistance and there is a little effect of applied impulse polarity on the soil ionization threshold field intensity. Although the ionization threshold field intensity of wet clay with 30% water content is the highest, its ionized zone was found to be the smallest amongst the test samples.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.467-472
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• 2008

In this paper, we analyzed the error rate Performance of convolution coded 16 QAM signal with Optimum Threshold Detection with selective combining diversity in Rician Fading Environments. The performance of 16-QAM signal with CTD (conventional threshold detection) which employs convolution coding technique was analyzed and the performance improvement of convolution coded 16-QAM signal with OTD (optimum threshold detection) which is varied according to fading parameter "K" and AWGN in Rician Fading channel was simulated. As a result of analysis, it was shown the effect of performance improvement to overcome the environment of mobile radio data communication channel.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.477-481
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• 2011

Composites of insulating polyethylene and carbon black are widely used in switching elements, conductive paint, and other applications due to the large gap of resistance value. This research addresses the critical exponent of dielectric breakdown strength of polymer matrix composites (PMC) made with carbon black and polyethylene below the percolation threshold (Pt) for the first time. Here, Pt means the volume fraction of carbon black of which the resistance of the PMC is transferred from its sharp decrease to gradual decrease in accordance with the increase of carbon-black-filled content. First, the Pt is determined based on the critical exponents of resistivity and relative permittivity. Although huge cohesive bodies of carbon black are formed in case of being less than the Pt, a percolation path connecting the conducting phases is not formed. The dielectric breakdown strength (Dbs) of the PMC below Pt is measured by using an impulse voltage in the range from 10 kV to 40 kV to avoid the effect of joule heating. Although the observed Dbs data seems to be well fitted to a straight line with a slope of 0.9 on a double logarithm of (Pt-$V_{CB}$) and Dbs, the least squares method gives a slope of 0.97 for the PMC. It has been found that finite carbon-black clusters play an important role in dielectric breakdown.

• Smart Structures and Systems
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• v.18 no.2
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• pp.217-231
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• 2016

The present work aims to develop piezoresistive sensors of excellent piezoresistive response attributable to change in nanoscale structures of multi-wall carbon nanotube (MWNT) embedded in cement. MWNT was distributed in a cement matrix by means of polymer wrapping method in tandem with the ultrasonication process. DC conductivity of the prepared samples exhibited the electrical percolation behavior and therefore the dispersion method adopted in this study was deemed effective. The integrity of piezoresistive response of the sensors was assessed in terms of stability, the maximum electrical resistance change rate, and sensitivity. A composite sensor with MWNT 0.2 wt.% showed the lowest stability and sensitivity, while the maximum electrical resistance change rate exhibited by this sample was the highest (96 %) among others and even higher than those found in the literature. This observation was presumably attributed by the percolation threshold and the tunneling effect. As a result of the MWNT content (0.2 wt.%) of the sensor being near the percolation threshold (0.25 wt.%), MWNTs were close to each other to trigger tunneling in response of external loading. The sensor with MWNT 0.2 wt.% was able to maintain the repeatable sensing capability while sustaining a vehicular loading on road, demonstrating the feasibility in traffic flow sensing application.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.121-127
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• 2003

The threshold value of the traitor-tracing schemes means a maximum number of traitors whose identities can be uniquely exposed using the tracing scheme. In the traitor-tracing scheme based on an error-correcting code, which is focused at this paper, the threshold value is determined by the error-correcting capability of the underlying error-correcting code. Analyzed in terms of a combinatorial property of the tracing scheme is the resulting effect on the tracing scheme when the collusion size is over the threshold value, and a possibility of two disjoint groups of users making an identical unauthorized decryption key is shown.