• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.1998-2016
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• 2012

Reliable spectrum sensing algorithm is a fundamental component in cognitive radio. In this paper, a non-cooperative spectrum sensing algorithm which needs only one cognitive radio node named CORDIC (Coordinate Rotation Digital Computer) Jacobi based method is proposed. The algorithm computes the eigenvalues of the sampled covariance of received signal mainly by shift and additional operations, which is suitable for hardware implementation. Based the latest random matrix theory (RMT) about the distribution of the limiting maximum and minimum eigenvalue ratio, the relationship between the probability of false alarm and the decision threshold is derived. Simulations and discussions show the method is effective. Real captured digital television (DTV) signals and Universal Software Radio Peripheral (USRP) are also employed to evaluate the performance of the algorithm, which prove the proposed algorithm can be applied in practical spectrum sensing applications.

• International Journal of Reliability and Applications
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• v.11 no.2
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• pp.69-87
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• 2010

The optimal replacement problem was investigated for a multi-state deteriorated system for which the true internal state cannot be observed directly except when the system breaks down completely. The internal state was assumed to be monitored incompletely by a monitor that gives information related to the true state of the system. The problem was formulated as a partially observable Markov decision process. The optimal procedure was found to be a monotone procedure with respect to stochastic increasing ordering of the state probability vectors under some assumptions. Limiting the optimal procedure to a monotone procedure would greatly reduce the tremendous amount of calculation time required to find the optimal procedure.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.569-571
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• 2003

As a definition of NERC, Available Transfer Capability(ATC) is a measure of the transfer capability remaining in the physical transmission network for the future commercial activity. To calculate ATC, accurate and defensible TTC, CBM and TRM should be calculated in advance. In this paper, we propose a method to quantify TRM using probabilistic load flow based on the method of moment. Generation output, bus voltages, loads, and line outages are considered as complex random variables (CRV) to take into account for uncertainties related to the transmission network conditions. Probability Density Function (PDF) of line flow at the most limiting line is used to quantify TRM with the desired probabilistic margin. Suggested method is compared with the results from conventional CPF method and verified using 24 bus MRTS, and the suggested method based on PLF shows efficiency and flexibility for the quantification of TRM compared with the conventional method.

• Industrial Engineering and Management Systems
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• v.15 no.1
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• pp.41-48
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• 2016

In this manuscript, a modified single sampling plan is proposed for the inspection of products in which the nonconforming items can be classified in to two categories namely critical and non-critical; and explained with the help of industrial example. The operating procedure of this plan is also proposed and the performance measures such as the probability of acceptance, average sample number, average total inspection and average out going quality are also derived. The optimal parameters are determined which will have minimum sample size. The efficiency of the proposed plan is also discussed over the conventional single sampling plan. The extensive tables for selecting a modified single sampling plan based on AQL and LQL are provided for both Binomial and Poisson distributions and explained with the help of industrial data.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.385-388
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• 1992

The transition probabilities for the thermal intramolecular electron transfer and the optical intervalence transfer band for a symmetric mixed-valence Cu(I)-Cu(II) compound were used to extract the PKS parameters $\varepsilon$ = -1.15, ${\lambda}$ = 2.839, and ${\nu}g$- = 923 $cm^{-1}$. These parameters determine the potential energy surfaces and vibronic energy levels. Three pairs of vibrational levels are below the top of the energy barrier in the lower potential surface. The contribution of each vibrational state to the intramolecular electron transfer was calculated. It is shown that the three pairs of vibrational states below the top of the barrier are responsible for most of the electron transfer at 261-306 K. So the intramolecular electron transfer in this system is a tunneling process. The transition probability exhibits the usual high-temperature Arrhenius behavior, but at lower temperature falls off to a temperature-independent value as tunneling from the lowest levels becomes the limiting process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.4
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• pp.593-597
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• 2019

We proposed a current Interruption type DC superconducting circuit breaker(I-DC SCB), a protection device that combines the current limiting technology of a superconductor with the cut-off technology of circuit breaker. Unlike existing protective devices, the current I-DC SCB is a device that combines two protection functions, notably improving failure probability and operational reliability. It is also applicable to all DC systems, such as HV, MV, and LVDC, due to the ease in capacity increase. The 100 kV I-DC SCB was designed after taking into account the actual power system conditions, followed by an analysis of the transient characteristics and the breaking range of the limiter. The results of the analysis showed that the I-DC SCB had a fault current limit of about 75% at the rated voltage, and completed the cut-off operation within about 20 ms.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.331-338
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• 2022

Face stability analyses provides the most probable failure mechanisms and the understanding about parameters that need to be considered for the evaluation of ground movements caused by tunneling. After the Upper Bound Method (UBM) solution which can consider the influence of seepage forces and depth-dependent effective cohesion is verified with the numerical experiments, the probabilistic model is proposed to calculate the unbiased limiting tunnel collapse pressure. A reliability analysis of a shallow circular tunnel driven by a pressurized shield in a frictional and cohesive soil is presented to consider the inherent uncertainty in the input parameters and the proposed model. The probability of failure that exceeding a specified applied pressure at the tunnel face is estimated. Sensitivity and importance measures are computed to identify the key parameters and random variables in the model.

• Earthquakes and Structures
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• v.18 no.4
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• pp.467-480
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• 2020

Concrete rectangular liquid storage tanks are widely used, but there are many cases of damage in previous earthquakes. Nonlinear fluid-structure interaction (FSI) is considered, Mooney-Rivlin material is used for rubber bearing, nonlinear contact is used for sliding bearing, numerical calculation models of no-isolation, rubber isolation, sliding isolation and hybrid isolation concrete rectangular liquid storage tanks are established; dynamic responses of different structures are compared to verify the effectiveness of isolation methods; and influences of earthquake amplitude, bidirectional earthquake and far-field long-period earthquake on dynamic responses are investigated. Results show that for liquid sloshing wave height, rubber isolation cause amplification effect, while sliding isolation and hybrid isolation have reduction effect; displacement of rubber isolation structure is much larger than that of sliding isolation with limiting-devices and hybrid isolation structure; when PGA is larger, wall cracking probability of no-isolation structure becomes larger, and probability of liquid sloshing wave height and structure displacement of rubber isolation structure exceeds the limit is also larger; under bidirectional earthquake, occurrence probabilities that liquid sloshing wave height and structure displacement of rubber isolation structure exceed the limit will be increased; besides, far-field long-period earthquake mainly influences structure displacement and liquid sloshing wave height. On the whole, control effect of sliding isolation is the best, followed by hybrid isolation, and rubber isolation is the worst.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.37.4-38
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• 2018

The HULQ project proposes to use gravitational lensing to determine the masses of QSO host galaxies, an otherwise difficult goal. If these host galaxy masses, along with their SMBH masses from single-epoch measurements, are estimated for a substantial number of QSOs at various redshifts, the co-evolution of SMBHs and their host galaxies can be studied for a large portion of the history of the universe. To determine the feasibility of this study, we present how to estimate the number of sources lensed by QSO hosts, i.e. the number of lensing QSO host galaxies (hereafter QSO lenses). SMBH masses in the literature are transformed into the velocity dispersions of their host galaxies using the M_BH -sigma relation, and in turn the Einstein radii for each QSO -source redshift combination is calculated, assuming singular isothermal spherical mass distributions. Using QSOs and galaxies as potential sources, the probability of a QSO host galaxy being a QSO lens is calculated, as a function of limiting magnitude. The expected numbers of QSO lenses are estimated for ongoing and future wide-imaging surveys, and the Hyper Suprime-Cam Wide survey is illustrated as an example.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.6
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• pp.713-728
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• 1989

In this paper, 16-QAM and 49-QPR systems utilized the raised cosine filter instead of LPF with the rectangular frequency characteristics as limiting channel bandwidth are implemented to measure their performances and effects of ISI. With the use of the raised cosine filter, and increase in SNR immunity can be obtained for specified spectrally efficient applications. Examination of the measured results reveals that the bandwidthe efficiency of 49-QPR implement is improved by about 8% and 15% higher than those of 16-QAM implement with the raised cosine characteristics having roll-off factor, a=0.5 and a=1, respectively. Also, equations for eye diagrams and error probability of 49-QPR system with AWGN and ISI are derived to analyze its performance and compared with the case of 16-QAM system.