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  • Title/Summary/Keyword: Geometrical Characteristics

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Porosity effects on post-buckling behavior of geometrically imperfect metal foam doubly-curved shells with stiffeners

  • Mirjavadi, Seyed Sajad;Forsat, Masoud;Yahya, Yahya Zakariya;Barati, Mohammad Reza;Jayasimha, Anirudh Narasimamurthy;Hamouda, AMS
    • Structural Engineering and Mechanics
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    • v.75 no.6
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    • pp.701-711
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    • 2020
  • This papers studies nonlinear stability and post-buckling behaviors of geometrically imperfect metal foam doubly-curved shells with eccentrically stiffeners resting on elastic foundation. Metal foam is considered as porous material with uniform and non-uniform models. The doubly-curved porous shell is subjected to in-plane compressive loads as well as a transverse pressure leading to post-critical stability in nonlinear regime. The nonlinear governing equations are analytically solved with the help of Airy stress function to obtain the post-buckling load-deflection curves of the geometrically imperfect metal foam doubly-curved shell. Obtained results indicate the significance of porosity distribution, geometrical imperfection, foundation factors, stiffeners and geometrical parameters on post-buckling characteristics of porous doubly-curved shells.

Numerical analysis of second-order effects of externally prestressed concrete beams

  • Lou, Tiejiong;Xiang, Yiqiang
    • Structural Engineering and Mechanics
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    • v.35 no.5
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    • pp.631-643
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    • 2010
  • A numerical procedure for the geometrical and material nonlinear analysis of concrete beams prestressed with external tendons is described, where the effects of external prestressing are treated as the equivalent loads applied on the concrete beams. The geometrical nonlinearity is considered not only the eccentricity variations of external tendons (second-order effects) but also the large displacement effects of the structure. The numerical method can predict the nonlinear response of externally prestressed concrete beams throughout the entire loading history with considerable accuracy. An evaluation of second-order effects of externally prestressed concrete beams is carried out using the proposed analysis. The analysis shows that the second-order effects have significant influence on the response characteristics of externally prestressed concrete beams. They lead to inferior ultimate load and strength capacities and a lower ultimate stress increase in tendons. Based on the current analysis, it is recommended that, for simply-supported externally prestressed beams with straight horizontal tendons, one deviator at midspan instead of two deviators at one-third span be furnished to minimize these effects.

Similarity Measurement Using Open-Ball Scheme for 2D Patterns in Comparison with Moment Invariant Method (Open-Ball Scheme을 이용한 2D 패턴의 상대적 닮음 정도 측정의 Moment Invariant Method와의 비교)

  • Kim, Seong-Su
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.1
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    • pp.76-81
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    • 1999
  • The degree of relative similarity between 2D patterns is obtained using Open-Ball Scheme. Open-Ball Scheme employs a method of transforming the geometrical information on 3D objects or 2D patterns into the features to measure the relative similarity for object(patten) recognition, with invariance on scale, rotation, and translation. The feature of an object is used to obtain the relative similarity and mapped into [0, 1] the interval of real line. For decades, Moment-Invariant Method has been used as one of the excellent methods for pattern classification and object recognition. Open-Ball Scheme uses the geometrical structure of patterns while Moment Invariant Method uses the statistical characteristics. Open-Ball Scheme is compared to Moment Invariant Method with respect to the way that it interprets two-dimensional patten classification, especially the paradigms are compared by the degree of closeness to human's intuitive understanding. Finally the effectiveness of the proposed Open-Ball Scheme is illustrated through simulations.

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Region-wise evaluation of gamma-ray exposure dose in decontamination operation after a nuclear accident

  • Jeong, Hae Sun;Hwang, Won Tae;Han, Moon Hee;Kim, Eun Han;Lee, Jo Eun;Lee, Cheol Woo
    • Nuclear Engineering and Technology
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    • v.53 no.8
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    • pp.2652-2660
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    • 2021
  • The gamma-ray exposure doses in decontamination operation after a nuclear accident were evaluated with a consideration of various geometrical conditions and specific gamma-ray energies. The calculation domain is organized with three residence types and each form is divided into two kinds of geometrical arrangements. The position-wise air KERMA values were calculated with an assumption of evenly distributed gamma-ray source based on Monte Carlo radiation transport analysis using the MCNP code. The radioactivity is initially set to be unity to be multiplied by the deposition value measured in the actual accident condition. The workforce data set depending on the target object was determined by modifying the Fukushima report. The external exposure doses for decontamination workers were derived from the calculated KERMA values and the workforce analysis. These results can be used to efficiently determine the workforce required by the characteristics of the area and the structure to be decontaminated within the dose limits.

Nonlinear resonance of porous functionally graded nanoshells with geometrical imperfection

  • Wu-Bin Shan;Gui-Lin She
    • Structural Engineering and Mechanics
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    • v.88 no.4
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    • pp.355-368
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    • 2023
  • Employing the non-local strain gradient theory (NSGT), this paper investigates the nonlinear resonance characteristics of functionally graded material (FGM) nanoshells with initial geometric imperfection for the first time. The effective material properties of the porous FGM nanoshells with even distribution of porosities are estimated by a modified power-law model. With the guidance of Love's thin shell theory and considering initial geometric imperfection, the strain equations of the shells are obtained. In order to characterize the small-scale effect of the nanoshells, the nonlocal parameter and strain gradient parameter are introduced. Subsequently, the Euler-Lagrange principle was used to derive the motion equations. Considering three boundary conditions, the Galerkin principle combined with the modified Lindstedt Poincare (MLP) method are employed to discretize and solve the motion equations. Finally, the effects of initial geometric imperfection, functional gradient index, strain gradient parameters, non-local parameters and porosity volume fraction on the nonlinear resonance of the porous FGM nanoshells are examined.

Study on Madeleine Vionnet Design Image Shown at the Christian Dior Collections (크리스찬 디오르 컬렉션에 나타난 마들렌 비오네 디자인 이미지)

  • Choi, Jin-Young;Cho, Kyu-Hwa
    • Journal of Fashion Business
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    • v.14 no.2
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    • pp.73-80
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    • 2010
  • This research examined the design characteristics of Madeleine Vionnet, a female fashion designer who left an enormous legacy and made a great contribution to the high added-value fashion industry. Her techniques can be dividing in to three types: the bias cutting, the design by geometrical methods, and the classical style of ancient Greek clothing. This research also intended to study the design cases in which Vionnet's drapery images are applied to modern fashion, mainly the haute couture works that have appeared at Dior collections since 2000. In terms of the characteristics of Madeleine Vionnet's design, First, she produced the best achievement in dress and ornament history by developing a new technique called bias cutting. Second, her work was groundbreaking because it changed the previously planar approach to the female body into a solid conception by cutting and connecting geometrical pieces in the form of quadrangle, triangle, and a quarter-circle. As a result, her works depicted feminine beauty to the fullest extent through the combination of the human body, excellent materials, and the most sophisticated technology and personal skill. Third, her approach was a classical style tinged with the Greek costume image. With this style, which was born by reinterpreting the key tone of the Greek epoch in a modern way, and transcending and even changing tradition, she created a form of beauty that only she could.

Analysis of Hydraulic Characteristics in Ice-Harbor Fishway (아이스하버식 어도에서의 수리학적 특성분석)

  • Ahn, Seung-Seop;Lee, Sang-Il;Lee, Zeung-Seok
    • Journal of Environmental Science International
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    • v.21 no.11
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    • pp.1395-1406
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    • 2012
  • The purpose of this study is to analyze the hydraulic characteristics of the ice-harbor fishway by considering its geometrical form and utilize such analysis results as the foundational database to be used when establishing fishways in the future. first of all, the study realizes the same form as an ice-harbor fishway that is currently implemented via a FLOW-3D model and estimated the parameters that were optimal to the numerical mock test. Then, this study analyzed the level of sensitivity of the flow conditions which fluctuated due to the changes in geometrical changes by adjusting the inclination and pocket spacing by using the estimated optimal parameters. As a result, the study arrived at the following conclusions. The vortical velocity increased and had a significant effect on the inclination of the fishway. Furthermore, as the velocity within the vorticity increased due to the narrowed vortical area, it was determined that further studies on vorticities or the determination of the design method for the decrease in vortical velocity were imperative.

Effect of grading pattern and porosity on the eigen characteristics of porous functionally graded structure

  • Ramteke, Prashik Malhari;Panda, Subrata K.;Sharma, Nitin
    • Steel and Composite Structures
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    • v.33 no.6
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    • pp.865-875
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    • 2019
  • The current article proposed to develop a geometrical model for the analysis and modelling of the uniaxial functionally graded structure using the higher-order displacement kinematics with and without the presence of porosity including the distribution. Additionally, the formulation is capable of modelling three different kinds of grading patterns i.e., Power-law, sigmoid and exponential distribution of the individual constituents through the thickness direction. Also, the model includes the distribution of porosity (even and uneven kind) through the panel thickness. The structural governing equation of the porous graded structure is obtained (Hamilton's principle) and solved mathematically by means of the isoparametric finite element technique. Initially, the linear frequency parameters are obtained for different geometrical configuration via own computer code. The comparison and the corresponding convergence studies are performed for the unidirectional FG structure for the validation purpose. Finally, the impact of different influencing parameters like aspect ratio (O), thickness ratio (S), curvature ratio (R/h), porosity index (λ), type of porosity (even or uneven), power-law exponent (n), boundary condition on the free vibration characteristics are obtained for the FG panel and discussed in details.

Study of the Characteristics of Dot Pattern Designs in Modern Fashion (현대패션에 나타난 도트문양의 표면유형과 특성에 관한 연구)

  • Kim, Sun-Young
    • Journal of the Korean Society of Costume
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    • v.59 no.4
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    • pp.41-53
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    • 2009
  • This study analyzed expression types of dot patterns and derived out inherent characteristics to provide fundamental resources for advancement of high value added creative designs. As a result of the study, Firstly, the circular motive was used to form silhouettes or as a symbol of a decoration. Secondly, a simple form and color dot pattern was used to create one side, or a circular shaped accessory was used to be recognized as a construction line or a decoration line. Thirdly, textile printing is mainly used but handicraft and decorative images were used to add vitality through piece technique, embroidery, collage, cut-out, patch work, etc. Fourthly, different circular motives were integrated, partitioned and duplicated for abstract geometrical images. Fifthly, variations were added by mixing different dot patterns that are arranged regularly and irregularly in different sizes and gaps creating compounded designs with handicraft touches, different angles or on top of each other. Sixthly, hybrid images were created with rearrangement of dot patterns and by adding floral shapes, stripes or other abstract and geometrical shapes. Such various and creative attempts construct new formative beauty in fashion design and I believe that it can establish the development of unique images that satisfies the taste of today's consumers.

Analysis of Radio-Wave Propagation Characteristics in Curved Tunnel (곡선 터널 내에서 전파특성 분석)

  • 김영문;정민석;진용옥;이범선
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.10
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    • pp.1017-1024
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    • 2002
  • In this paper, we present the analysis of radio wave propagation characteristics in curved tunnels. Tunnel propagation models are performed in two cases which are using ray-tracing method for straight tunnels and geometrical optics extension to the standard hybrid waveguide model for curved ones. By regression analysis for measured power based on distance between the transmitter and the received antenna in tunnels that have 3.5 m × 6 m cross section and limited wall depth path loss are 0.19 dB/m for straight section and 0.68 dB/m for curved ones. By comparing model analysis with measurement in tunnels, it has been shown that the simulated results of tunnel propagation models are similar to the measured values.