• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.9
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• pp.791-801
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• 2012

Currently, SEAMCAT has been widely used as a tool to evaluate the effects of interference among a variety of wireless communication systems. This supports various channel propagation models, all of which are based on some statistical models for the channel propagation and do not exploit any specific terrain characteristics. Thus it is not appropriate for assessing the effects of interference between wireless systems, given some specific terrain features. In order to overcome this limit in its use, it is necessary to extend the capability of SEAMCAT to support a channel propagation model which takes into account terrain informations. The ITU-R P.526 is a familiar channel propagation model which calculates the path loss considering the terrain features. In this paper, we present an enhanced version of SEAMCAT which supports the ITU-R P.526 and provide a few examples of interference evaluation using it.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.138-149
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• 2018

In this paper, we propose a system model which effectively mitigates impulsive noise that degrades the performance of power line communication. Recently, deep learning have shown effective performance improvement in various fields. In order to mitigate effective impulsive noise, we applied a convolution neural network which is one of deep learning algorithm to conventional system. Also, we used a successive interference cancellation scheme to mitigate impulsive noise generated from multi-users. We simulate the proposed model which can be applied to the power line communication in the Section V. The performance of the proposed system model is verified through bit error probability versus SNR graph. In addition, we compare ZF and MMSE successive interference cancellation scheme, successive interference cancellation with optimal ordering, and successive interference cancellation without optimal ordering. Then we confirm which schemes have better performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.72-81
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• 2009

In this paper, we investigate a spectrum sharing scheme based on the interference temperature (IT), that is a recently introduced receiver-centric metric by FCC. We extend the existing frequency sharing procedure for single CR to the one for multiple CRs (or secondary users, SUs). In the proposed interference model, we consider the practical operating characteristics of primary users (PUs), stochastically activated (ON)/deactivated (OFF) at the time axis, and analyze quantitatively the CR user capacity based on the model. We define the instantaneous capacity for idle time-slot channel allocation and the mean capacity averaging this instantaneous capacity and use them for a proper frequency sharing. Apart from existing schemes, the proposed frequency sharing scheme changes the frequency parameters adaptively depending on the channel characteristics and does not need any sensing information from PUs. Through computer simulation, we verify the proposed model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.963-968
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• 2009

This paper deals with shrink fit analysis of rotor by 2D cross-section, 2D axis-symmetry, and 3D FEM model. And this paper presents 2nd order approximation function of thermal expansion displacement by design variables (shape dimension, heating temperature, sleeve length, interference etc.), table of orthogonal array and RSM(response surface methodology). The possibility of the rotor with shrink fit is evaluated by thermal expansion displacement. If thermal expansion displacement is larger than interference, shrink fit enable to make the rotor. 2D axis-symmetry model and 3D model are more reasonable than 2D cross-section model, because stress and strain is different along length of shaft.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.240-246
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• 2013

In heterogeneous networks, the almost blank subframes (ABS) for inter-cell interference coordination (ICIC), which can be protected from the CCI due to unutilized subframes (i.e., ABS) is proposed. However, the analytical model for ABS-based systems has not been fully studied yet. In this paper, we derive a new analytical model to evaluate the performance of ABS-based systems. In an analytic model, we assume that each carrier in multicarrier systems, such as in OFDMA, is subject to large-scale fading, which is independent of other carriers. As a performance measure, we present the cumulative distribution function (CDF) for the effective SINR. We show the accuracy of the analytical model via simulation results.

• Journal of the Korean Society for Railway
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• v.5 no.2
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• pp.118-124
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• 2002

The failure probability of wheel beyond 10$\^$7/ cycles is achieved by the strengths-stress interference model for the evaluation of fatigue strength and reliability in the wheel, From plane bending fatigue test results, the fatigue life (N$\_$f/) for the smooth and 200㎛ holed specimens can be represented as $\sigma$$\_$a/ = 1326N$\_$f/$\^$-0.10/ and $\sigma$$\_$a/ = 2894N$\_$f/$\^$-0.18/. Respectively, fatigue strength of the wheel at beyond 10$\^$7/cycles was about 332 MPa. And, the fatigue strength for the specimen with a micro hole (d=200㎛) which simulated an inclusion on the wheel surface was about 235 MPa. Thus, a micro hole (d=200㎛) caused about 30% reduction of fatigue strength of the specimen. The failure probabilities for the smooth and micro-holed specimens, derived from the strength-stress interference model, are 0.0148% and 13.05%, respectively. The current finding suggests that at least 200 ㎛ sized inclusion, which might be produced during manufacturing process, will cause a critical effect on integrity of the railway vehicle.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.895-905
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• 1999

This paper identifies a linear time-invariant mathematical model of each stand of a five-stand tandem cold mill to design a robust $H_\infty$ thickness controller by applying input and output data sets to N4SID (Numerical algorithms for Subspace State Space System Identification) method. The input-output data sets describe interstand interference in the process of tandem cold rolling and are obtained from a nonlinear simulator of the tandem cold mill. In result, it is shown that the identified model well approximates the nonlinear model than a Taylor linearized model. Furthermore, uncertainties including roll eccentricity and incoming strip variation are quantitatively analyzed from the plot of maximum singular values.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1873-1877
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• 2010

In the high-speed EMU, the modularized traction converter produces the significant harmonic currents caused from the switching behavior of a power converter. These harmonic currents bring the interference among the traction equipment. One way to minimize the interference is to design the secondary windings of a power transformer decoupled magnetically as possible. This paper presents a magnetic field analysis on a winding disposition to clarify an impact on magnetic decoupling between secondary windings, under a limited height of a train. Two winding dispositions for a single-phase shell-type transformer are constructed and simulated by a three-dimensional finite elements method (FEM) model. Two different winding dispositions are constructed and simulated by three-dimensional FEM model using Maxwell3D.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1521-1528
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• 2000

In this paper we analyze the performance of a DS/CDMA system in LEO mobile satellite channels. The channel uses the Extended Suzuki model which is the product of a Rician distribution having a LOS component and a lognormal distribution due to shadowing. We assume that the signal transmitted from the satellite to the mobile undergoes the same fading for the whole coverage of signal's beam. The average bit error probabilities of double coverage system is calculated in this paper. The interference resulting from the reference satellite is calculated for mobile located in the middle of the double coverage region whereas the additive interference from next-satellite is included for mobile located in the edge of the double coverage region. The performance of the mobile's receiving signal is dependent on shadowing and the interference of the next-satellite. We can obtain an obtain an improved average bit error probability by using dual diversity over the conventional correlated receiver for similar shadowing conditions in the coverage area of the satellite channel.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.86-88
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• 2019

In a complex geographical environment, communication quality of communication equipment is being seriously challenged. Secondary Users(SUs) must make the best possible use the idle spectrums that Primary Users(PUs) do not use and change spectrum frequently. Using the relevance vector machine(RVM) to establish a signal noise Ratio(SNR) Model for interference information and bit error rate(BER). Through the model and real-time interference information, the minimum channel SNR meeting the BER requirements of communication equipment can be predicted, and we can also calculate the minimum transmitted power. According to the simulation results, this method has better performance for selecting available channel and restraining interference.