• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1987-1992
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• 2004

A Variable Structure Model Reference Adaptive Controller (VS-MRAC) using state Variables is proposed for single input multi output systems. . The structure of the switching functions is designed based on stability requirements, and global exponential stability is proved. Transient behavior is analyzed using sliding mode control and shows perfect model following at a finite time. The effect of input disturbances on stability and transients is investigated and shows preference to the conventional MRAC schemes with integral adaptation law. Sliding surfaces are independent of system parameters and therefore VS-MRAC is insensitive to system parameter variations. Simulation is presented to clear the theoretical results.

• 천문학회지
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• 제42권5호
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• pp.107-123
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• 2009

We investigate the wave properties for isothermal plasma state around to the de Sitter black hole's horizon using 3+1 split of spacetime. The corresponding Fourier analyzed perturbed perfect GRMHD equations are used to obtain the complex dispersion relations. We obtain the real values of the wave number k, from these relations, which are used to evaluate the quantities like phase and group velocities etc. These have been analyzed graphically in the neighborhood of the horizon.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.301-310
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• 2001

Lim et al.(1998) proposed the Bayesian Imperfect Repair Model, in which a failed system is perfectly repaired with probability P and is minimally repaired with probability 1 - P, where P is not fixed but a random variable with a prior distribution II(p). In this note, the steady state availability of the model is derived and the measure is obtained for several particular prior distribution functions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권10호
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• pp.4157-4175
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• 2020

Moving target defense, as a 'game-changing' security technique for network warfare, realizes proactive defense by increasing network dynamics, uncertainty and redundancy. How to select the best countermeasure from the candidate countermeasures to maximize defense payoff becomes one of the core issues. In order to improve the dynamic analysis for existing decision-making, a novel approach of selecting the optimal countermeasure using game theory is proposed. Based on the signal game theory, a multi-stage adversary model for dynamic defense is established. Afterwards, the payoffs of candidate attack-defense strategies are quantified from the viewpoint of attack surface transfer. Then the perfect Bayesian equilibrium is calculated. The inference of attacker type is presented through signal reception and recognition. Finally the countermeasure for selecting optimal defense strategy is designed on the tradeoff between defense cost and benefit for dynamic network. A case study of attack-defense confrontation in small-scale LAN shows that the proposed approach is correct and efficient.

• Geomechanics and Engineering
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• 제10권3호
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• pp.325-334
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• 2016

Rock salt is a near-perfect material for gas storage repositories due to its excellent ductility and low permeability. Gas storage in rock salt layers during gas injection and gas production causes the stress redistribution surrounding the cavity. The triaxial cyclic loading and unloading tests for rock salt were performed in this paper. The elastic-plastic deformation behaviour of rock salt under cyclic loading was observed. Rock salt experienced strain hardening during the initial loading, and the irreversible deformation was large under low stress station, meanwhile the residual stress became larger along with the increase of deviatoric stress. Confining pressure had a significant effect on the unloading modulus for the variation of mechanical parameters. Based on the theory of elastic-plastic damage mechanics, the evolution of damage during cyclic loading and unloading under various confining pressure was described.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권8호
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• pp.3789-3808
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• 2017

This paper studies a multi-antenna wireless relay network in the presence of a jammer. In this network, the source node transmits signals to the destination node through a multi-antenna relay node which adopts the amplify-and-forward scheme, and the jammer attempts to inject additive signals on all antennas of the relay node. With the linear beamforming scheme at the relay node, this network can be modeled as an equivalent Gaussian arbitrarily varying channel (GAVC). Based on this observation, we deduce the mathematical closed-forms of the capacities for two special cases and the suboptimal achievable rate for the general case, respectively. To reduce complexity, we further propose an optimal structure of the beamforming matrix. In addition, we present a second order cone programming (SOCP)-based algorithm to efficiently compute the optimal beamforming matrix so as to maximize the transmission rate between the source and the destination when the perfect channel state information (CSI) is available. Our numerical simulations show significant improvements of our propose scheme over other baseline ones.

• 한국실내디자인학회논문집
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• 제25호
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• pp.184-190
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• 2000

If we take account of the Architectural Tradition which aims a construction of better environment, we can see that this tradition has ended historically toward Utopia. It is a continual trend from ancient to contemporary epoch especially in each transitional periods. Utopia is an ideal commonwealth in which inhabitants exist under perfect conditions, ideally perfect places or state of things. But, Dystopia implies skeptical perspective on the future which has emerged as a result of the increasing awareness about crisis concerning negative aspects highlighted by progress of science and technology since Modern era. Dystopia is the opposite of Utopia which was a propaganda used by Modern architecture and has characteristics of Post-Modernity. Utopias plans are complete projects of image, its goal is an improvement according to the eras. Its plans are characterized by rigid geometrical pattern as circle and square, which contain generally center·axis·enclosure·boundary·symmetry. Recent architectural circumstances no longer reflect utopian visions. Dystopias plans have described extreme mechanism, destructive offense, expression of fragmentation and differentiation in contemporary architecture. Therefore, as the Utopian architecture describes characteristics of the era unlike the continuity of its concept, the Dystopian architecture will find its expression differently while maintaining its basic concept and intention.

• 한국산학기술학회논문지
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• 제11권2호
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• pp.614-619
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• 2010

수산시장이나 어항에서 발생하는 수산폐기물을 수거하여 처리하는 과정은 긴 시간과 불결한 처리로 악취발생 및 비위생적인 면이 많아 민원의 대상이 되어 왔다. 이것을 수거하여 완전 처리하는 기술을 적용하면 비위생에 대한 민원이 없어지고 자원재활용의 비율을 확실히 높일 수 있다. 본 논문에서는 지방과 단백질이 풍부한 수산폐기물을 증류건조시켜, 고형물은 가축사료로 활용하고 응축수는 탈취제나 하수처리장의 외부탄소원으로 활용하는 완전 재활용공법을 소개한다.

• 영어어문교육
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• 제17권4호
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• pp.177-191
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• 2011

This paper examines nursing professionals' English abstract to learn their preferences towards tense and voice choices. A total of 24 abstracts, completed reviews to be published by the editorial board members of the Korea Industrial Nursing Association, were analyzed for the study. Each sentence in the four parts of the abstract (Purpose, Methods, Results, and Conclusion) was examined and classified into active/passive voices, and present/past/present perfect tenses. Verbs were then further identified to see which ones were commonly preferred to state the objectives of the study, methods, and to draw conclusions. Hedging expressions in Conclusion were also examined. The results of the present study revealed that Purpose was mostly (79%) stated in the past tense with slight use (17%) of the present tense in the form of 58% active and 42% passive voice whereas Methods were dominantly (96%) illustrated in the past tense with preference of mixed active and passive voice. The Results were also preferably (92%) stated in past tense and Conclusion in both present and past tense. Verbs used by these nursing professionals seemed diverse; however, hedging appeared to be narrowly limited to a few expressions including suggest and should. More diverse English hedging expressions need to be taught at least college level writing so that the EFL learners and writers can have a better understanding of presenting statements in an appropriate level of caution, confidence, or uncertainty.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.14-17
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• 1999

The wrinkling behavior of a thin sheet with perfect geometry is a kind of compressive instability. The compressive instability is influenced by many factors such as stress state mechanical properties of the sheet material geometry of the body contact conditions and plastic anisotropy. The analysis of compressive instability in plastically deforming body is difficult considering all the factors because the effects of the factors are very complex and the instability behavior may show wide variation for small deviation of the factors. In this study the bifurcation theory is introduced for the finite element analysis of puckering initiation and growth of a thin sheet with perfect geometry. All the above mentioned analysis and the post-bifurcation behavior is analyzed by introducing the branching scheme proposed by Riks. The finite element formulation is based on the incremental deformation theory and elastic-plastic material modeling. in order to investigate the effect of plastic anisotropy on the compressive instability a square plate that is subjected to compression in one direction and tension in the other direction is analyzed by the above-mentionedfinite element analysis. The critical stress ratios above which the buckling does not take place are found for various plastic anisotropic modeling method and discussed. Finally the effect of plastic anisotropy on the puckering behavior in the spherical cup deep drawing process is investigated.