• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3965-3982
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• 2015

Event detection is one of the key issues in many wireless sensor network (WSN) applications. The uncertainties that are derived from the instability of sensor node, measurement noise and incomplete sampling would influence the performance of event detection to a large degree. Many of the present researches described the sensor readings with crisp values, which cannot adequately handle the uncertainties inhered in the imprecise sensor readings. In this paper, a fault-tolerant event detection algorithm is proposed based on Dempster-Shafer (D-S) theory (also called evidence theory). Instead of crisp values, all possible states of the event are represented by the Basic Probability Assignment (BPA) functions, with which the output of each sensor node are characterized as weighted evidences. The combination rule was subsequently applied on each sensor node to fuse the evidences gathered from the neighboring nodes to make the final decision on whether the event occurs. Simulation results show that even 20% nodes are faulty, the accuracy of the proposed algorithm is around 80% for event region detection. Moreover, 97% of the error readings have been corrected, and an improved detection capability at the boundary of the event region is gained by 75%. The proposed algorithm can enhance the detection accuracy of the event region even in high error-rate environment, which reflects good reliability and robustness. The proposed algorithm is also applicable to boundary detection as it performs well at the boundary of the event.

• The Journal of the Korea Contents Association
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• v.7 no.12
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• pp.199-208
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• 2007

The Employment instability of current employees should be related to uncertainty of switching job for experienced ones. Therefore, the researcher would like to look into the influence which is taken by Job Insecurity after verifying Job Instability Recognition through employees and identification of the level into Trust in organization, In particular, for the employee who is working in a catering department and expected to be ranked highly among tourist companies concerning Job Instability Recognition. According to the result of a tentative theory that Job Insecurity will effect negatively to Trust, conversely, it does not give any considerable effects both Trust in colleague and company. It just turned out that the risky factor of their dismissal could come to a substantial consequence to Trust in Superior. In this regard, a study shows that there isn't any relation to Trust in colleague even though there Is the cause of being fired. In this sense, employees can assume that a work evaluation or relationship with their superior, who work together in the field, is related to the risky factor regarding their dismissal. In other words, it turned out that there was no difference between regular employee and non-regular employee in the matter of Job-Instability-Recognition.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.95-103
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• 2016

In this paper, aeroelastic instability and aerodynamic damping ratio of a helical $180^{\circ}$ model which shows better aerodynamic behavior in both along-wind and crosswind responses on a super tall building was investigated by an aeroelastic model test, and the aerodynamic damping ratio was evaluated from the wind-induced responses of the model by using Random Decrement Technique. Aerodynamic damping ratios evaluated in this study were verified through comparison with previous results obtained by quasi-steady theory. As a result, the aeroelastic instability of the helical $180^{\circ}$ model in crosswind direction were not occurred for any conditions with increasing the reduced wind velocity while the square model generally encounters aeroinstability due to the vortex shedding. The aerodynamic damping in along-wind direction for the helical $180^{\circ}$ and the square model increased monotonically both with reduced wind velocity, i.e., there is no relation with modifications of building shapes. On the other hand, in crosswind direction, the characteristics of aerodynamic damping ratio with reduced wind velocity for helical $180^{\circ}$ model were quit different from those of the square model.

• Advances in nano research
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• v.9 no.3
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• pp.133-145
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• 2020

In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

• The Journal of Internal Korean Medicine
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• v.31 no.4
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• pp.837-845
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• 2010

It has been shown that bilateral decrease of point H4,5,6 in Ryodoraku test is related with gastric dysmotility. This suggested that the system of Kyung-Rak related with anatomical gastric disease may not be the Stomach Meridian, in the view that the system of Kyung-Rak is similar to that of Ryodoraku, and which was not consistent with classical contents of Kyung-Rak principle. Therefore, this paper was done to investigate whether bilateral decrease of point H4,5,6 is a general sign of common gastric disease in Ryodoraku test and to study its relation between Kyung-Rak principle and autonomic nervous system as a mediator explaining Ryodoraku response. As shown in the results of this study, different electrical response of Ryodoraku between patients with dyspepsia of gastric dysmotility and gastric ulcer revealed discrepancy of location indicating anatomical stomach between Kyung-Rak principle and Ryodoraku and instability of explanation of autonomic nerve theory to Ryodoraku. Thus, it presented the possibility that artificial application of Kyung-Rak principle against Ryodoraku may destroy its originality in the clinical field. To correctly use Ryodoraku in the diagnosis or evaluation of disease, Ryodoraku test should be used according to Nakatani's suggestion and clinical indication of which is limited to the diseases complicated with dysfunction of the autonomic nervous system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1352-1358
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• 2012

The dynamic analysis of delaminated composite structures is carried out based on the higher order plate theory. In the finite element (FE) formulation, the seven degrees of freedom per each node are used with transformations in order to fit the displacement continuity conditions at the delamination region. The boundaries of the instability regions are determined using the method proposed by Bolotin. The numerical results obtained for skew plates are in good agreement with those reported by other investigators. The new results for delaminated skew plate structures in this study mainly show the effect of the interactions between the geometries and other various parameters.

• Steel and Composite Structures
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• v.17 no.4
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• pp.453-470
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• 2014

This article is the result of an investigation on the influence of a Pasternak elastic foundation on the stability of exponentially graded (EG) cylindrical shells under hydrostatic pressure, based on the first-order shear deformation theory (FOSDT) considering the shear stresses. The shear stresses shape function is distributed parabolic manner through the shell thickness. The governing equations of EG orthotropic cylindrical shells resting on the Pasternak elastic foundation on the basis of FOSDT are derived in the framework of Donnell-type shell theory. The novelty of present work is to achieve closed-form solutions for critical hydrostatic pressures of EG orthotropic cylindrical shells resting on Pasternak elastic foundation based on FOSDT. The expressions for critical hydrostatic pressures of EG orthotropic cylindrical shells with and without an elastic foundation based on CST are obtained, in special cases. Finally, the effects of Pasternak foundation, shear stresses, orthotropy and heterogeneity on critical hydrostatic pressures, based on FOSDT are investigated.

• Advances in biomechanics and applications
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• v.1 no.3
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• pp.211-225
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• 2014

The usual assumption that the increase of fractures in aging bone is due entirely to lower bone density is taken back with respect to the possibility that aging bone fractures result from a loss of stability, or buckling, in the structure of the bone lattice. Buckling is an instability mode that becomes likely in end-loaded structures when they become too slender and lose lateral support. The relative importance of bone density and architecture in etiology bone fractures are poorly understood and the need for improved mechanistic understanding of bone failure is at the core of important clinical problems such as osteoporosis, as well as basic biological issues such as bone formation and adaptation. These observations motivated the present work in which simplified adaptive-beam buckling model is formulated within the context of the adaptive elasticity (Cowin and Hegedus 1976, Hegedus and Cowin 1976). Our results indicate that bone loss activation process leads systematically to the apparition of new elastic instabilities that can conduct to bone-buckling mechanism of fracture.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.10 no.3
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• pp.345-353
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• 2003

Purpose: The purpose of this study was to explore the stress-coping process used by elderly people. Method: This study was based on the grounded theory methodology of Strauss & Corbin. The participants were 15 elders selected by theoretical sampling. Over a period of 3 months, in-depth interviews using audiotape recording were used to collect the data. The data were analyzed simultaneously by a constant comparative method in which new data were continuously coded in categories and properties according to Strauss and Corbin's methodology, Result: Stress in elderly people is caused by illness, family conflict, and loss of economic power. Stress occurred in connection with aging and limitation of social activity. The central incidents for stress were fear, alienation and anxiety. It was found that action/interactional strategies of stress-coping behavior were related to social support and mobility disorders. Action/interactional strategies to stress-coping in elderly people were dependent on medical treatment, mind control, participation of social activity, and renunciation of offensive behavior. Stress-coping in elderly people resulted in stability or instability in body and mind. Conclusion: It is suggested that the results of this study may contribute to the development stress-coping strategies for elderly people. There is need to develop social support systems and a positive environment to avoid negative coping strategies.

• Structural Engineering and Mechanics
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• v.67 no.1
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• pp.21-31
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• 2018

In this work, the dynamic stability of carbon nanotubes (CNTs) reinforced composite pipes conveying pulsating fluid flow is investigated. The pipe is surrounded by viscoelastic medium containing spring, shear and damper coefficients. Due to the existence of CNTs, the pipe is subjected to a 2D magnetic field. The radial induced force by pulsating fluid is obtained by the Navier-Stokes equation. The equivalent characteristics of the nanocomposite structure are calculated using Mori-Tanaka model. Based on first order shear deformation theory (FSDT) or Mindlin theory, energy method and Hamilton's principle, the motion equations are derived. Using harmonic differential quadrature method (HDQM) in conjunction with the Bolotin's method, the dynamic instability region (DIR) of the system is calculated. The effects of different parameters such as volume fraction of CNTs, magnetic field, boundary conditions, fluid velocity and geometrical parameters of pipe are shown on the DIR of the structure. Results show that with increasing volume fraction of CNTs, the DIR shifts to the higher frequency. In addition, the DIR of the structure will be happened at lower excitation frequencies with increasing the fluid velocity.