• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.218-222
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• 2007

This paper presents a new Perfect Tracking Control (PTC) scheme for linear systems with state constraint. The proposed controller increases the number of the steps on-line for perfect tracking to satisfy the given ellipsoid-type state constraint. The unavoidable step delay that we impose is minimized by solving LMI feasibility problems and the possible feedback information loss is avoided. The proposed schemes are easy to develop, theoretically simple and clear, and include the conventional PTC as its special case.

• ETRI Journal
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• v.45 no.6
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• pp.929-938
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• 2023

The detection of all the symbols transmitted simultaneously in multiuser systems using limited wireless resources is challenging. Traditional model-based methods show high performance with perfect channel state information (CSI); however, severe performance degradation will occur if perfect CSI cannot be acquired. In contrast, data-driven methods perform slightly worse than model-based methods in terms of symbol error ratio performance in perfect CSI states; however, they are also able to overcome extreme performance degradation in imperfect CSI states. This study proposes a novel deep learning-based method by improving a state-of-the-art data-driven technique called deep soft interference cancellation (DSIC). The enhanced DSIC (EDSIC) method detects multiuser symbols in a fully sequential manner and uses an efficient neural network structure to ensure high performance. Additionally, error-propagation mitigation techniques are used to ensure robustness against channel uncertainty. The EDSIC guarantees a performance that is very close to the optimal performance of the existing model-based methods in perfect CSI environments and the best performance in imperfect CSI environments.

• Korean Journal of Veterinary Research
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• v.30 no.1
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• pp.59-64
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• 1990

The present study was conducted in order to elucidate the asymptomatic carrier state of dermatophytes on the laboratory rodents in Korea during the period from August 1986 to April 1987. A total of 988 laboratory rodents, comprising 393 albino rats, 285 albino mice, 238 guinea pigs and 72 hamsters, were randomly selected for the isolation of dermatophytes from 6 research institutes and 2 breeding farms. And the mating experiments were performed to identified the perfect states of Trichophyton mextagrophytes isolated from albino rats. Dermatophytes were recovered from 94 of 393(23.9%) albino rats and from 3 of 5 colonies. Isolation rate of each colony was 38.4%, 32.0% and 9.8%, respectively, and the albino rats over 2 months old(28.2%) were higher than below 2 months old(2.9%) in the isolation rate of dermatophytes. Among 94 strains of dermatophytes isolated from albino rats, all the strains were identified T mentagrophytes, except 1 strain of Microsporum gypseum, and its perfect states were Arthroderma $vanbreuseghemii^+$.

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.559-569
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• 2004

In this paper we shall discuss the quasi-perfect automata associated with power automata. We shall give the fact that its power automaton is invertible if an automaton A is quasi-perfect. Moreover, some subgroups and normal subgroups of the characteristic semigroup X(M) will have the very interesting parts in their structures.

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.571-583
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• 2004

In this paper we shall discuss the quasi-perfect automata associated with power automata. We shall give the fact that x(M)/ HX is normal subgroup of the characteristic semigroup x(M) if the automaton A is quasi-perfect and x(M)/HX = x$(M)_H$ if A is perfect. Moreover, it is a very interesting part that x$(M)_H$ is conjugate to x$(M)_{Ha}$ for every a $\in$ X. Also we shall give a characterization of Ha = Hb for x$(M)_H$.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.1
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• pp.1-14
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• 2009

When the stagnation temperature increases, the specific heat does not remain constant and start to vary with this temperature. The gas is perfect, it's state equation remains always valid, except, it was called by gas calorically imperfect or gas at high temperatures. The purpose of this work is to develop a mathematical model for a normal shock wave normal at high temperature when the stagnation temperature is taken into account, less than the dissociation of the molecules as a generalisation model of perfect for constant heat specific. A study on the error given by the perfect gas model compared to our model is presented in order to find a limit of application of the perfect gas model. The application is for air.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.735-740
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• 2008

Recently, the research of PM (Preventive Maintenance) method on the RCM(Reliability-Centered Maintenance) of the system equipment is being actively advanced for a few years. For the most of the current power equipment maintenance, the state of the equipment after maintenance is assumed to be becoming 'as good as new ones' state. However, the state of the power equipment is maintained like the states of the between 'as good as new ones' and 'as bad as old ones' by imperfect maintenance that implies the life decrease of the equipment by frequent breakdown, the error of maintenance process, and so on. So, the Maintenance method considering the real case has to reflect Imperfect maintenance than perfect maintenance. This paper suggests the Preventive Maintenance method by using Quasi - Renewal Theory for the gas turbine equipment as deliberating the imperfect maintenance for the real cases.

• 한국데이터정보과학회:학술대회논문집
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• 2002.06a
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• pp.17-22
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• 2002

Availability is an important characteristic of a repairable component. Iyer(1992) obtained the 'limiting efficiency'(not the `steady state availability') of the age-dependent minimal repair model which was first considered by Block et al.(1985). However the existence of the steady state availability of the model has not been reported. In this note, the existence of the steady state availability of the model is shown and a brief remark on the importance of the property is given.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.253-271
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• 2017

In this paper, considering that perfect channel state information (CSI) is hard to achieve in practice, the downlink capacity of distributed antenna systems (DAS) with imperfect CSI and multiple receive antennas is investigated over composite Rayleigh fading channel. According to the performance analysis, using the numerical calculation, the probability density function (PDF) of the effective output SNR is derived. With this PDF, accurate closed-form expressions of ergodic capacity and outage probability of DAS with imperfect CSI are, respectively, obtained, and they include the ones under perfect CSI as special cases. Besides, the outage capacity of DAS in the presence of imperfect CSI is also derived, and a Newton's method based practical iterative algorithm is proposed to find the accurate outage capacity. By utilizing the Gaussian distribution approximation, another approximate closed-form expression of outage capacity is also derived, and it may simplify the calculation of accurate outage capacity. These theoretical expressions can provide good performance evaluation for downlink DAS for both perfect and imperfect CSI. Simulation results verify the effectiveness of the theoretical analysis, and the system capacity can be improved by increasing the receive antennas, and decreasing the estimation error or path loss. Moreover, the system can tolerate the estimation error variance up to about 0.01 with a slight degradation in the capacity.

• Communications of the Korean Mathematical Society
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• v.34 no.3
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• pp.911-920
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• 2019

In this paper we characterize semiconformally flat spacetimes and a spacetime with harmonic semiconformal curvature tensor. At first in a semiconformally flat perfect fluid spacetime we obtain a state equation and prove that in particular for dimension n = 4, the spacetime represents a model for incoherent radiation. Next we prove that perfect fluid spacetime with harmonic semiconformal curvature tensor is of Petrov type I, D or O and the spacetime is a GRW spacetime. As a consequence we obtain several corollaries.