• Smart Structures and Systems
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• v.21 no.5
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• pp.653-668
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• 2018

This work proposes and investigates re-centering negative stiffness dampers (NSDs) for vibration suppression in high-speed trains. The merit of the negative stiffness feature is demonstrated by active controllers on a high-speed train. This merit inspires the replacement of active controllers with re-centering NSDs, which are more reliable and robust than active controllers. The proposed damper design consists of a passive magnetic negative stiffness spring and a semi-active positioning shaft for re-centering function. The former produces negative stiffness control forces, and the latter prevents the amplification of quasi-static spring deflection. Numerical investigations verify that the proposed re-centering NSD can improve ride comfort significantly without amplifying spring deflection.

• Smart Structures and Systems
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• v.16 no.3
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• pp.479-496
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• 2015

In this work, a novel artificial circular muscle based on shape memory alloy (S.M.A.) is proposed. The design is inspired from the natural circular muscles found in certain organs of the human body such as the small intestine. The heating of the prestrained SMA artificial muscle will induce its contraction. In order to measure the mechanical work provided in this case, the muscle will be mounted on a silicone rubber cylindrical tube prior to heating. After cooling, the reaction of the rubber tube will involve the return of the muscle to its prestrained state. A finite element model of the new SMA artificial muscle was built using the software "ABAQUS". The SMA thermomechanical behavior law was implemented using the user subroutine "UMAT". The numerical results of the finite element analysis of the SMA muscle are presented to shown that the proposed design is able to mimic the behavior of a natural circular muscle.

• Structural Engineering and Mechanics
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• v.17 no.5
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• pp.655-670
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• 2004

This paper aims to evaluate the effect of typhoons on fatigue damage accumulation in steel decks of long-span suspension bridges. The strain-time histories at critical locations of deck sections of long-span bridges during different typhoons passing the bridge area are investigated by using on-line strain data acquired from the structural health monitoring system installed on the bridge. The fatigue damage models based on Miner's Law and Continuum Damage Mechanics (CDM) are applied to calculate the increment of fatigue damage due to the action of a typhoon. Accumulated fatigue damage during the typhoon is also calculated and compared between Miner's Law and the CDM method. It is found that for the Tsing Ma Bridge case, the stress spectrum generated by a typhoon is significantly different than that generated by normal traffic and its histogram shapes can be described approximately as a Rayleigh distribution. The influence of typhoon loading on accumulative fatigue damage is more significant than that due to normal traffic loading. The increment of fatigue damage generated by hourly stress spectrum for the maximum typhoon loading may be much greater than those for normal traffic loading. It is, therefore, concluded that it is necessary to evaluate typhoon induced fatigue damage for the purpose of accurately evaluating accumulative fatigue damage for long-span bridges located within typhoon prone regions.

• Journal of Smart Tourism
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• v.1 no.2
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• pp.3-12
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• 2021

The interaction between technology and tourism has been a dynamic research area recently. This study aims to review the progress and development of technology in tourism research via a bibliometric analysis. We derive the source data from the Web of Science (WoS) core collection and use CiteSpace for bibliometric analysis, including countries, institutions, authors, categories, references, and keywords. The analysis results are as follows: i) The number of published articles on the role of technology in tourism has increased in recent years. ii) Technology-related articles in tourism are abundant in Tourism Management, Journal of Travel Research, and Annals of Tourism Research. iii) The countries with the most contributions are China, the US, and the UK. The most active institutions are the Hong Kong Polytechnic University, University of Central Florida, Bournemouth University, University of Queensland, and Kyung Hee University. iv) The reference analysis results identify eight extensively researched topics from the most cited papers, and the keyword burst analysis results present an emerging trend. This study identifies the effect and development of technology in tourism research. Our findings provide implications for researchers about the current research focus of technology and the future research trend of technology in the tourism field.

• Structural Engineering and Mechanics
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• v.82 no.5
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• pp.611-628
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• 2022

Energy-dissipative rocking (EDR) columns are a class of seismic mitigation device capable of dissipating seismic energy and preventing weak-story failure of moment resisting frames (MRFs). An EDR consists of two hinge-supported steel columns interconnected by steel dampers along its height. Under earthquakes, the input seismic energy can be dissipated by plastic energy of the steel dampers in the EDR column. However, the unrecoverable plastic deformation of steel dampers generally results in residual drifts in the structural system. This paper presents a proof-of-concept study on an innovative device, namely self-centring energy-dissipative rocking (SC-EDR) column, aiming at enabling self-centring capability of the EDR column by installing a set of shape memory alloy (SMA) tension braces. The working mechanism of the SC-EDR column is presented in detail, and the feasibility of the new device is carefully examined via experimental and numerical studies considering the parameters of the SMA bar diameter and the steel damper plate thickness. The seismic responses including load carrying capacities, stress distributions, base rocking behaviour, source of residual deformation, and energy dissipation are discussed in detail. A rational combination of the steel damper and the SMA tension braces can achieve excellent energy dissipation and self-centring performance.

• Interaction and multiscale mechanics
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• v.6 no.3
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• pp.287-300
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• 2013

In this paper, the effect of impulsive line on the propagation of shear waves in non-homogeneous elastic layer is investigated. The rigidity and density in the intermediate layer is assumed to vary quadratic as functions of depth. The dispersion equation is obtained by using the Fourier transform and Green's function technique. The study ends with the mathematical calculations for transmitted wave in the layer. These equations are in complete agreement with the classical results when the non-homogeneity parameters are neglected. Various curves are plotted to show the effects of non-homogeneities on shear waves in the intermediate layer.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.246-249
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• 2002

A mobile agent system that searches for meaningful information from web XML documents is developed. For this, a domain information was conceptualized and a universal DTD generator is developed. A mobile agent with the universal DTD is dispatched to remote sites, extracts meaning information, and transmits the information back to a host. This way of information filtering is able to enhance the quality of information and reduce the network transmission overhead.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.4
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• pp.52-63
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• 2003

This study proposes a change from the currentexpected price integrated system, which is based on the standard of estimated unit manpower and material, to a new actual construction cost integrated system. In order to implement it, the standard method of measurement organization system as well as the communication area standard of estimated unit manpower and material should be changed Moreover, the work breakdown structure and itemized structure should be assorted.

• Journal of the Korean Mathematical Society
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• v.55 no.1
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• pp.17-28
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• 2018

In this paper, we enlarge the ball of convergence of a uniparametric family of secant-like methods for solving non-differentiable operators equations in Banach spaces via using ${\omega}$-condition and centered-like ${\omega}$-condition meantime as well as some fine techniques such as the affine invariant form. Numerical examples are also provided.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.69-72
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• 2007

In this paper, we analyze the performance of the network management system with intelligent mobile agent system. The proposed system dynamically selects appropriate its destinations. Thus, the system has an advantage of flexible network management in mobile network environments as well as dynamic change of traffic. Comparing its delay and throughput performance with the conventional SNMP based network management system, we find that the proposed mobile agent system performs better efficiency than the conventional one.