• Coupled systems mechanics
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• v.13 no.2
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• pp.95-113
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• 2024

In this paper, we will analyse the thermo-elastic behavior of the plate element of a structure arranged in a climatically aggressive environment (extreme temperature), we use a refined four-variable thick plate theory to take the shear effect into consideration, the proposed theory less computationally expensive and more accurate so that it incorporates the shear effect into the formulation. The plate is assumed to be simply supported on its four edges, so exact (closed-form) solutions are found according to the Navier expansion, and the governing stability equations and associated boundary conditions of the problem are obtained via the virtual works principle. The plate studied ismade of laminated composite materials, so a parametric study is needed to see the effect of different types of parameters and coupling on the critical temperature value causing thermo-elastic instability of the plate and also on the natural frequency of free vibration, as well as for other parameters such as anisotropy, slenderness and aspect ratio of the plate and finally the lamination angle. Numerical results are obtained for specially orthotropic and antisymmetrical plates and are compared with those obtained by othertheoriesin the literature to validate the analysis approach used.

• Structural Engineering and Mechanics
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• v.32 no.1
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• pp.179-191
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• 2009

A stochastic response spectrum method is proposed for simple evaluation of the structural response of an actively controlled aseismic structure. The response spectrum is constructed assuming a linear structure with an active mass damper (AMD) system, and an earthquake wave model given by the product of a non-stationary envelope function and a stationary Gaussian random process with Kanai-Tajimi power spectral density. The control design is executed using a linear quadratic Gaussian control strategy for an enlarged state space system, and the response amplification factor is given by the combination of the obtained statistical response values and extreme value theory. The response spectrum thus produced can be used for simple dynamical analyses. The response factors obtained by this method for a multi-degree-of-freedom structure are shown to be comparable with those determined by numerical simulations, demonstrating the validity and utility of the proposed technique as a simple design tool. This method is expected to be useful for engineers in the initial design stage for structures with active aseismic control.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.3
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• pp.77-85
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• 2018

Multi-User Multiple-Input Multiple-Output (MU-MIMO) is the core technology for improving the channel capacity compared to Single-User MIMO (SU-MIMO) by using multiuser gain and spatial diversity. Key problem for the MU-MIMO is the user selection which is the grouping the users optimally. To solve this problem, we adopt Extreme Value Theory (EVT) at the beginning of the proposed algorithm, which defines a primary user set instead of a single user that has maximum channel power according to a predetermined threshold. Each user in the primary set is then paired with all of the users in the system to define user groups. By comparing these user groups, the group that produces a maximum sum rate can be determined. Through computer simulations, we have found that the proposed method outperforms the conventional technique yielding a sum rate that is 0.81 bps/Hz higher when the transmit signal to noise ratio (SNR) is 30 dB and the total number of users is 100.

• Journal of the Semiconductor & Display Technology
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• v.18 no.2
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• pp.63-66
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• 2019

Due to the development of medical imaging technology, different imaging technologies provide a large amount of effective information. However, different imaging method caused the limitations of information integrity by using single type of image. Combining different image together so that doctor can obtain the information from medical image comprehensively. Image registration algorithm based on mutual information has become one of the hotspots in the field of image registration with its high registration accuracy and wide applicability. Because the information theory-based registration technology is not dependent on the gray value difference of the image, and it is very suitable for multimodal medical image registration. However, the method based on mutual information has a robustness problem. The essential reason is that the mutual information itself is not have enough information between the pixel pairs, so that the mutual information is unstable during the registration process. A large number of local extreme values are generated, which finally cause mismatch. In order to overcome the shortages of mutual information registration method, this paper proposes a registration method combined with image spatial structure information and mutual information.

• The Korean Journal of Financial Management
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• v.24 no.3
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• pp.133-152
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• 2007

In this paper, we examine a portfolio selection model in which a safety-first investor maximizes expected return subject to a downside risk constraint. We use the Value-at-Risk as the downside risk measure. We exploit the fact that returns are fat-tailed, and use a semi-parametric method suggested by Jansen, Koedijk and de Vries(2000). We find a more realistic asset allocation than the one suggested by the literature based on the traditional mean-variance framework. For the robustness check, we provide empirical analyses using empirical quantiles. The results highlight that for optimal portfolio selection involving downside risks that are far in the tails of the distribution, our mean-VaR model with a fat-tailed distribution is superior.

• Wind and Structures
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• v.30 no.1
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• pp.85-97
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• 2020

The accurate estimation of the buffeting response of a bridge pylon is related to the quality of the bridge construction. To evaluate the influence of wind field characteristics on the buffeting response of a pylon in a trumpet-shaped mountain pass, this paper deduced a multimodal coupled buffeting frequency domain calculation method for a variable-section bridge tower under the twisted wind profile condition based on quasi-steady theory. Through the long-term measurement of the wind field of the trumpet-shaped mountain pass, the wind characteristics were studied systematically. The effects of the wind characteristics, wind yaw angles, mean wind speeds, and wind profiles on the buffeting response were discussed. The results show that the mean wind characteristics are affected by the terrain and that the wind profile is severely twisted. The optimal fit distribution of the monthly and annual maximum wind speeds is the log-logistic distribution, and the generalized extreme value I distribution may underestimate the return wind speed. The design wind characteristics will overestimate the buffeting response of the pylon. The buffeting response of the pylon is obviously affected by the wind yaw angle and mean wind speed. To accurately estimate the buffeting response of the pylon in an actual construction, it is necessary to consider the twisted effect of the wind profile.

• The Journal of Engineering Geology
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• v.5 no.1
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• pp.45-58
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• 1995

A probabilistic seismic risk in the Korean Peninsula is calculated from the instrumental eaathquake data. For the purpose, an instrumental earthquake catalogue since 1905 m which parameters are readjusted to have uniformity and homogeneity in description is cornpiled through the review of all available data. The maximum potential earthquake expected in the Korean Peninsula for 100, 1000, and 4000 years are estimated to be 6.3, 7.2 and 7.8 in magnitude, respectively, from Gumbel's extreme value theory. In addition, contour rnaps representing the maximum ground acceleration expected for 100 and 1000 years are prepared using the return period method. Seismic hazart] curves in which maximum ground acceleration expressed in terms of probability of occurrence are also presented for the major populated areas.

• Journal of Korean Philosophical Society
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• v.146
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• pp.115-135
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• 2018

This article attempts to deal with the problem that science and technology function as a mechanism to oppress and exploit humans rather than to release humans from labor. To explore this subject, it is necessary to consider the difference between the theory of labor value and the theory of 'technology value'. In addition, it is also important to refer to Marx's critical view of the 'capitalist' use of technology. Above all, Marx' concepts of relative surplus value and special surplus value, and his analysis of organic composition of capital are still valid in explaining that development of technology tightens control over workers and intensity of labor, and worsens instability of employment. Reflection of the limitations of capitalist development of technology is also important for realization of its usefulness. Industry 4.0 in Germany therefore deserves to be noticed as a good example because it shows a different way from extreme capitalist exploitation. The model suggests also some points that shouldn't be overlooked, when we try to actualize the tremendous slogan of the current fourth industrial revolution as real innovation and progress in human life. In this matter, the most important point is the possibility of technological development that doesn't oppose workers' interests.

• Physical Therapy Korea
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• v.21 no.4
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• pp.56-66
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• 2014

For maintaining adequate psychometric properties when reducing the number of items from an instrument, item level psychometrics is crucial. Strategies such as low item correlation or factor loadings, using classical test theory, have traditionally been advocated. The purpose of this study is to describe the development of a new short form assessing the impact of low back pain on physical activity. Rasch measurement model has been applied to the International Classification of Functioning, Disability and Health Activity Measure (ICF-AM). One hundred and one individuals with low back pain aged 19-89 years (mean age: $48.1{\pm}17.3$) who live in the community were participated in the study. Twenty-seven items of lifting/carrying construct of the ICF-AM were analyzed. Ten items were selected from the construct to create a short form. Item elimination criteria include: 1) high or low mean square (out of the range: .6-1.4 for the fit statistics), 2) similar item calibrations to adjacent items, 3) person separation value, and item-person map for potential gap in person ability continuum. All 10 items of the short form fit to the Rasch model except one item (i.e., carrying toddler on back). Despite its high infit and outfit statistics (1.90/2.17), the item had to be reinstated due to potential gaps at the upper extreme of person ability level. The short form had a slightly better spread of person ability continuum compared to the entire set of item. The created short form separated individuals with low back pain into nearly 4 groups, while the entire set of items separated the individuals into 6 groups. The findings prompted multidimensional models for better explanation of the lifting/carrying domain. The item level psychometrics based on the Rasch model can be useful in developing short forms with rationally retained items.

• Fashion & Textile Research Journal
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• v.14 no.4
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• pp.519-531
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• 2012

This study comprehends the various expressions of Lady Gaga's fashion style based on Craig Owens's Allegory theory. This study analyzed four application elements of Borrow, Site Specificity, Accumulate of Strategy, and Hybridization in addition, it studied all aspects of the aesthetic value of Lady GaGa (an influential popular culture icon). It was classified in the external representation of the fashion style for the aesthetic value. The results are summarized as follows: First, 'Borrow' of the singers of the 80's music and fashion style present from her elders and visual homage to shock artists. It influenced her fans with a difference in viewpoint for a star's fashion that subsequently resulted in a deformation of form, playful kitsch style, and mixed gender. Second, 'Site specificity' presents an extreme make over through an intentional and grotesques fashion style to extend physical territory and defenseless. The results remove stereotypes and reveal deconstructive performances. Third, 'Accumulate of strategy' simultaneously presents voluptuous beauty, futurism, and avant-garde style. This shows the countercultural tendency through the random repetition of fashion images and layerd coordination. Finally, 'Hybridization' presents multiful fashion style through a collaboration with world-famous designers and cosmetic brands. She expressed a diverse and complex fashion style composed of an art form that combines a high-tech cyborg image. The aesthetic values of Lady Gaga' fashion style are 'ambivalence virtuality', 'Transcendental mixed gender', 'plural textuality', and 'unexpected play culture'.