• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.751-764
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• 2023

In practical engineering such as aerial refueling pipes, the boundary of the fluid-conveying pipe is difficult to be completely immovable. Pipes under movable and immovable boundaries are controlled by different dominant nonlinear factors, where the boundary mobility will affect the nonlinear dynamic characteristics, which should be focused on for adopting different strategies for vibration suppression and control. The nonlinear dynamic instability characteristics of functionally graded fluid-conveying pipes lying on a viscoelastic foundation under movable and immovable boundary conditions are systematically studied for the first time. Nonlinear factors involving nonlinear inertia and nonlinear curvature for pipes with a movable boundary as well as tensile hardening and nonlinear curvature for pipes with an immovable boundary are comprehensively considered during the derivation of the governing equations of the principal parametric resonance. The stability boundary and amplitude-frequency bifurcation diagrams are obtained by employing the two-step perturbation- incremental harmonic balance method (TSP-IHBM). Results show that the movability of the boundary of the pipe has a great influence on the vibration amplitude, bifurcation topology, and the physical meanings of the stability boundary due to different dominant nonlinear factors. This research has guidance significance for nonlinear dynamic design of fluid-conveying pipe with avoiding in the instability regions.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.301-305
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• 2016

We investigate proton conduction in a nonstoichiometric ${\Sigma}3$ $BaZrO_3$ (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as -0.70 and -0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.71-87
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• 2015

Mobile users want to be provided with undisrupted network services when they navigate on the Next-Generation (NG) wireless networks. For that, interlocking with a heterogeneous network is important, but there have been few studies on the method for guaranteeing global mobility. Thus, this paper proposes the Proxy-LMA technique, the mobile IP-based global inter-networking system, to enhance global mobility and interoperability within the Next-Generation (NG) network environment. The purpose of the proposed Proxy-LMA system is to expand the boundary of the mobility with regards to the existing mobility management protocol (PMIPv6 and MIPv6) in order to guarantee global mobility and interoperability within the heterogeneous network environment. The results of the performance evaluation showed that the proposed Proxy-LMA system was more efficient than other methods from the standpoint of signaling cost and delay in the heterogeneous network environment.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.189-190
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• 2007

We propose an efficient internetworking model for fast handover between UMTS and WLAN networks. Mobility anchor (MA) is provided at the boundary between GGSN and PDG, under the 3GPP-proposed internetworking reference model. Such MA can enable authentication and session initialization before L2 handover of the mobile terminal, so that seamless and fast vertical handover could be possible.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.483-490
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• 1997

Thin film Si has been used in sensors, radiation detectors, and solar cells. The carrier mobility of thin film Si influences the device behavior through its frequency response or time response. Since poly-Si shows the higher mobility value, a-Si:H films on Mo substrate were subjected to various crystallization treatments. Consequently, we need to find an appropriate method in mobility measurement before and after the anneal treatment. This paper investigates the carrier mobility improvement with anneal treatments and summarizes the mobility measurement methods of the a-Si:H and poly-Si film. Various techniques were investigated for the mobility determination such as Hall mobility, HS, TOF, SCLC, TFT, and TCO method. We learned that TFT and TCO method are suitable for the mobility determination of a-Si:H and poly-Si film. The measured mobility was improved by $2{\sim}3$ orders after high temperature anneal above $700^{\circ}C$ and grain boundary passivation using an RF plasma rehydrogenation.

• Physical Therapy Rehabilitation Science
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• v.10 no.2
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• pp.124-133
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• 2021

Objective: In order to secure the right to walk for the weak, such as the disabled, this study aims to suggest ways to improve the pedestrian environment by identifying factors that cause obstacles to walking. Design: Data Analysis and Perception Survey. Methods: The questionnaire was conducted separately between users of personal mobility vehicle and non-users. A total of 207 effective questionnaires were collected, and the analysis analyzed the perception of personal mobility vehicle by conducting frequency analysis using SAS 9.4. The survey focused on basic information on respondents, walking conditions, understanding of personal mobility vehicle, awareness of pedestrian space passage and parking, and awareness of the possibility of securing pedestrian rights due to new regulations. Results: First, when moving a pedestrian path by personal mobility vehicle, it shall be limited to less than the walking speed of pedestrians. Second, the parking location of the personal mobility vehicle is located at the boundary of the pedestrian road and the lane. Third, pay a fair price to park in a pedestrian space. Conclusions: It is necessary to improve the system to strengthen the contents of education to take into account the safety of pedestrians in education on how to use personal mobility vehicle.

• Journal of the Korean Ceramic Society
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• v.32 no.10
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• pp.1117-1122
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• 1995

The effect of grain boundary structure on zigzag migrtion has been studied. Five kinds of a(2110)-m(1010) diffusion couples with different twist angles by 30$^{\circ}$from a [0001] common direction of each plane were prepared. When chromia (Cr2O3) was added to the diffusion couples by a vapor phase, zigzag migration of the grain boundary occurred. The fraction of zigzag migration did not essentially vary with the twist angle, but the magnitude and migration distance of individual migrating segment varied. The variation of CIGM morphology thus appears to result from the change in grain boundary mobility due to microscopic deviation of grain boundary structure out of a macroscopic grain boundary orientation.

• The Journal of the Acoustical Society of Korea
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• v.31 no.3
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• pp.142-150
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• 2012

The waveguide finite element (WFE) method is a useful numerical technique to investigate wave propagation along waveguide structures which have uniform cross-sections along the length direction ('x' direction). In the present paper, the vibration and radiated noise of the submerged pipe with fluid is investigated numerically by coupling waveguide finite elements and wavenumber boundary elements. The pipe and internal fluid are modelled with waveguide finite elements and the external fluid with wavenumber boundary elements which are fully coupled. In order to examine this model, the point mobility, dispersion curves and radiated power are calculated and compared for several different coupling conditions between the pipe and internal/external fluids.

• Transactions on Electrical and Electronic Materials
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• v.1 no.2
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• pp.7-11
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• 2000

a-Si:H and poly-Si TFT(thin film transistor) characteristics were investigated using an inverted staggered type TFT. The TFT an as-grown a-Si:H exhibited a low field effect mobility, transconductance, and high gate threshold voltage. The poly-Si films were achieved by using an isothermal and RTA treatment for glow discharge deposited a-Si:H films. The a-Si:H films were cystallized at the various temperature from 600$^{\circ}C$ to 1000$^{\circ}C$. As anneal temperature was elevated, the TFT exhibited increased g$\sub$m/ and reduced V$\sub$ds/. V$\sub$T/. The poly-Si grain boundary passivation with grain boundary trap types and activation energies as a function of anneal temperature. The poly-si TFT showed an improved I$\sub$nm//I$\sub$off/ ratio of 10$\^$6/, reduced gate threshold voltage, and increased field effect mobility by three orders.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.450-453
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• 1999

In this paper, The relationship between device performance and channel length(1.5-50$\mu$m) in polysilicon thin-film transistors fabricated by SPC technology was Investigated by measuring electric Properties such as 1-V characteristics, field effect mobility, threshold voltage, subthreshold swing, and trap density in grain boundary with channel length. The drain current at ON-state increases with decreasing channel length due to increase of the drain field, while OFF-state current (leakage current) is independent of channel length. The field effect mobility decrease with channel length due to decreasing carrier life time by the avalanche injection of the carrier at high drain field. The threshold voltage and subthreshold swing decrease with channel length, and then increase in 1.5 $\mu$m increase of increase of trap density in grain boundary by impact ionization.