• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.655-658
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• 2012

Recently, Gu and Xue proposed an improved secret handshakes scheme with unlinkability by modifying the Huang-Cao scheme. Their proposal not only solves security weakness in the Huang-Cao scheme but also is more efficient than previously proposed secret handshakes schemes. In this letter, we examine the correctness of Gu and Xue's security requirements and show that the adversary model is not correctly defined. We also show that the Gu-Xue scheme is not secure against the attacks under correctly defined adversary model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1742-1760
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• 2017

Recent evolution in the open access internet technology demands that the identifying information of a user must be protected. Authentication is a prerequisite to ensure the protection of user identification. To improve Qu et al.'s scheme for remote user authentication, a recent proposal has been published by Huang et al., which presents a key agreement protocol in combination with ECC. It has been claimed that Huang et al. proposal is more robust and provides improved security. However, in the light of our experiment, it has been observed that Huang et al.'s proposal is breakable in case of user impersonation. Moreover, this paper presents an improved scheme to overcome the limitations of Huang et al.'s scheme. Security of the proposed scheme is evaluated using the well-known random oracle model. In comparison with Huang et al.'s protocol, the proposed scheme is lightweight with improved security.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.127-132
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• 2009

In the working population, muscle fatigue and musculoskeletal discomfort are common, which, in the case of insufficient recovery may lead to musculoskeletal pain. Workers suffering from musculoskeletal pains need to be rehabilitated for recovery. Isokinetic testing has been used in physical strengthening, rehabilitation and post-operative orthopedic surgery. Frequency analysis of electromyography (EMG) signals using the mean frequency (MNF) has been widely used to characterize muscle fatigue. During isokinetic contractions, EMG signals present strong nonstationarities. Hilbert-Haung transform (HHT) and autoregressive (AR) model have been known more suitable than Fourier or wavelet transform for nonstationary signals. Moreover, several analyses have been performed within each active phase during isokinetic contractions. Thus, the aims of this study were i) to determine which one was better suitable for the analysis of MNF between HHT and AR model during repetitive maximum isokinetic extensions and ii) to investigate whether the analysis could be repeated for sequential fixed epoch lengths. Seven healthy volunteers (five males and two females) performed isokinetic knee extensions at $60^{\circ}/s$ and $240^{\circ}/s$ until 50% of the maximum peak torque was reached. Surface EMG signals were recorded from the rectus femoris of the right thigh. An algorithm detecting the onset and offset of EMG signals was applied to extract each active phase of the muscle. Following the results, slopes from the least-square error linear regression of MNF values showed that muscle fatigue of all subjects occurred. The AR model is better suited than HHT for estimating MNF from nonstationary EMG signals during isokinetic knee extensions. Moreover, the linear regression can be extracted from MNF values calculated by sequential fixed epoch lengths (p> 0.0I).

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.49-60
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• 2020

To solve the edge ringing or block effect caused by the partial differential diffusion in image enhancement domain, a new image enhancement algorithm based on bidirectional diffusion, which smooths the flat region or isolated noise region and sharpens the edge region in different types of defect images on aviation composites, is presented. Taking the image pixel's neighborhood intensity and spatial characteristics as the attribute descriptor, the presented bidirectional diffusion model adaptively chooses different diffusion criteria in different defect image regions, which are elaborated are as follows. The forward diffusion is adopted to denoise along the pixel's gradient direction and edge direction in the pixel's smoothing area while the backward diffusion is used to sharpen along the pixel's gradient direction and the forward diffusion is used to smooth along the pixel's edge direction in the pixel's edge region. The comparison experiments were implemented in the delamination, inclusion, channel, shrinkage, blowhole and crack defect images, and the comparison results indicate that our algorithm not only preserves the image feature better but also improves the image contrast more obviously.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.386-397
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• 2007

One major development in bridge life cycle cost analysis (LCCA) in recent years is to develop deterioration model for bridge components so that the times of repair/replacement throughout a component's life span can be properly determined. Taiwan also developed her own bridge LCCA model in 2003, integrating with the bridge inspection database in the local bridge management system (T-BMS). Under the framework of the local LCCA model, this study employs the reliability method in developing a deterioration model of bridge components. A component deteriorates through time in its reliability, which represents the probability of a component's condition index exceeds a user specified threshold. Model assumptions and rationale are described in the paper. The steps for applying the developed model are explained in detail. Results and findings are reported.

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.162.2-162.2
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• 2001

• International Journal of Knowledge Content Development & Technology
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• v.6 no.1
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• pp.5-39
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• 2016

Social networking applications (SNAs) are among the fastest growing web applications of recent years. In this paper, we propose a causal model to assess the success of SNAs, grounded on DeLone and McLean's updated information systems (IS) success model. In addition to their original three dimensions of quality, i.e., system quality, information quality and service quality, we propose that a fourth dimension - networking quality - contributes to SNA success. We empirically examined the proposed research model with a survey of 168 Facebook and 149 Twitter users. The data validates the significant role of networking quality in determining the focal SNA's success. The theoretical and practical implications are discussed.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.420-427
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• 2011

In this study, numerical simulations of transonic aircraft configurations are performed with various turbulence models and the effect of turbulence models on flow separation are examined. A three-dimensional RANS code and three turbulence models are used for the study. The turbulence models incorporated to the code include Menter's ${\kappa}-{\omega}$ model, Coakley's $q-{\omega}$, and Huang and Coakley's ${\kappa}-{\omega}$, model. Using the code, numerical simulations of DLR-F6 configurations obtained from AIAA CFD Drag Prediction Workshop are conducted. Flow separations on the wing-body juncture and the wing lower surface near pylon are observed. and flow features of the regions are compared with experimental data and other numerical results.

• Journal of computational fluids engineering
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• v.20 no.1
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• pp.47-56
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• 2015

In this paper, we study the effect of various turbulence models by comparing the aerodynamic characteristics and the flow patterns computed for aircraft models. An in-house CFD solver, MSAPv, that solves the three dimensional RANS equations with the turbulence model equations is used. The turbulence models used in this study are the Spalart-Allmaras model, Menter's $k-{\omega}$ SST model, Coakley's $q-{\omega}$ model, and Huang and Coakley's $k-{\varepsilon}$ model. DLR-F6 WB and WBNP configurations are selected for the study. We concentrate on the separated flow pattern variations with the turbulence models at the wing-body junction and the wing-pylon junction as well as drag polar curves.

• Steel and Composite Structures
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• v.21 no.3
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• pp.553-571
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• 2016

The progressive collapse potential of steel moment framed structures due to abrupt removal of a column is investigated based on the energy principle. Based on the changes of component's internal energy, this paper analyzes structural member's sensitivity to abrupt removal of a column to determine a sub-structure resisting progressive collapse. An energy-based structural damage index is defined to judge whether progressive collapse occurs in a structure. Then, a simplified beam damage model is proposed to analyze the energies absorbed and dissipated by structural beams at large deflections, and a simplified modified plastic hinges model is developed to consider catenary action in beams. In addition, the correlation between bending moment and axial force in a beam during the whole deformation development process is analyzed and modified, which shows good agreement with the experimental results.