• Title/Summary/Keyword: Idealized university

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Safety Evaluation of Horizontal and Vertical Bolted Connection between PHC Piles Using Finite Element Analysis (유한요소해석을 통한 수평 및 수직볼트로 체결된 PHC 파일 연결부의 안전성 평가)

  • Kim, Su Eun;Kim, Sung Bo
    • Journal of Korean Society of Steel Construction
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    • v.30 no.2
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    • pp.97-104
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    • 2018
  • The safety evaluation of horizontal and vertical bolted connection between PHC piles is presented. The numerical analysis model is constructed using the commercial finite element program, ABAQUS, in which 3D solid element is used to model all the connection devices. The actual bolted connection is idealized by the contact and tie condition given in ABAQUS. Through the finite element analysis, the compression, tensile, bending and shear behaviors of PHC pile connection were analyzed. The safety factor based on Von-Mises and yield stress was calculated for the safety evaluation of each connection devices.

Dynamic Characteristics of Semi-Active Shock Absorber Using Electrorheological Fluid (ER 유체를 이용한 반능동 완충장치의 동적 특성)

  • Kim, Do-Hyung;Cho, Ki-Dae;Jung, Yong-Hyun;Lee, In;Oshima, Nobuo;Fukuda, Takehito
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.11 no.4
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    • pp.13-21
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    • 2001
  • Electrorheological(ER) fluid is a kind of smart material with variable shear stress and dynamic viscosity under various electric field intensity. Electric field can control the damping characteristics of ER damper. The objective of this study is the analysis of the performance of ER damper and its application to shock absorber. Idealized nonlinear Bingham plastic shear flow model is used to predict the velocity profile between electrodes. Cylindrical dashpot ER damper with moving electrode is constructed and tested under various electric fields. The analytic and experimental results for damping force are compared and discussed. Drop test system using ER damper is prepared to identify transient vibration characteristics. The rebound is eased as the applied electric field increases. When semi-active control algorithm is applied, rebound phenomenon disappears and vibration energy level decays faster than the case of zero electric field.

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Seismic Design for Application of LNG Storage Tank Isolation System (LNG 저장탱크의 면진시스템 적용을 위한 내진설계)

  • Seo, Ki-Young;Park, Hyun-Jae;Kim, Nam-Sik;Kim, Jae-Min;Yang, Seong-Yeong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.3
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    • pp.227-235
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    • 2014
  • The demand of natural gas is gradually increasing as a clean fuel in the world. Therefore, LNG storage tanks and related facilities of the importance of leading a community-based facility have emerged. The seismic design of LNG storage tank including seismic analysis have been developed steadily. But, the seismic analysis and design techniques for LNG storage tanks are lacking, in Korea. Consequently, it is necessary to develop an analysis model that LNG storage tanks in isolation system can describe the behavior. Further, LNG storage tank capable of ensuring safety and economy, it is necessary to develop design techniques. The studies have suggested seismic design procedures of LNG storage tanks with isolation system including triple-FPB and idealized complex hysteresis model of triple-FPB.

Intrusion of a Magnetic Field through the Overlying Field in the Solar Atmosphere Induced by Ballooning Instability

  • Jun, Hong-Da;Choe, G.S.
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.1
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    • pp.26.2-26.2
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    • 2010
  • It has been a puzzle in solar physics how a low-lying magnetic structure such as a solar prominence surrounded by a strongly line-tied overlying field sometimes intrudes through the latter and goes into eruption. A numerical simulation study of the solar coronal plasma reveals that a ballooning instability can explain this type of eruptive process. We consider an idealized situation with two flux ropes merging. When magnetic field lines from different flux ropes reconnect, a new field line connecting farther footpoints is generated. Since the field line length abruptly increases, the field line expands outward. If the plasma beta is low, this expansion takes place more or less evenly over the whole field line. If, on the other hand, the plasma beta is high enough somewhere in this field line, the outward expansion is not even, but is localized as in a bulging balloon. This ballooning section of the magnetic field penetrates out of the overlying field, and eventually the originally underlying field and the overlying field come to interchange their apex positions. This process may explain how a field structure that has stably been confined by an overlying field can occasionally show a localized eruptive behavior.

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Maximum damage prediction for regular reinforced concrete frames under consecutive earthquakes

  • Amiri, Gholamreza Ghodrati;Rajabi, Elham
    • Earthquakes and Structures
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    • v.14 no.2
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    • pp.129-142
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    • 2018
  • The current paper introduces a new approach for development of damage index to obtain the maximum damage in the reinforced concrete frames caused by as-recorded single and consecutive earthquakes. To do so, two sets of strong ground motions are selected based on maximum and approximately maximum peak ground acceleration (PGA) from "PEER" and "USGS" centers. Consecutive earthquakes in the first and second groups, not only occurred in similar directions and same stations, but also their real time gaps between successive shocks are less than 10 minutes and 10 days, respectively. In the following, a suite of six concrete moment resisting frames, including 3, 5, 7, 10, 12 and 15 stories, are designed in OpenSees software and analyzed for more than 850 times under two groups of as-recorded strong ground motion records with/without seismic sequences phenomena. The idealized multilayer artificial neural networks, with the least value of Mean Square Error (MSE) and maximum value of regression (R) between outputs and targets were then employed to generate the empirical charts and several correction equations for design utilization. To investigate the effectiveness of the proposed damage index, calibration of the new approach to existing real data (the result of Park-Ang damage index 1985), were conducted. The obtained results show good precision of the developed ANNs-based model in predicting the maximum damage of regular reinforced concrete frames.

A Fundamental Study for Time History Modeling of Fluid Impact Pressure (유체 충격압력 시계열의 모델링에 관한 기초 연구)

  • Nho, In-Sik;Lee, Jae-Man;Yeom, Cheol-Woong
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.2
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    • pp.242-247
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    • 2010
  • To consider effects of essential parameters of water impact pressure on dynamic structural responses of bow bottom structures, a parametric study for a ship bottom panel is carried out. The idealized pressure time history models were assumed by triangular and rectangular shapes in time domain. The main loading parameters are duration time and peak pressure value maintaining the same impulse value. The structural models for local bottom stiffened panels of a container ship are analysed. The natural frequency analysis and transient dynamic response analysis are performed using MSC/NASTRAN. Added mass effects of contacting water are considered and the pressure distributions are assumed to be uniform in the whole water contacting surface. The effects of loading parameters on the structural responses, especially maximum displacements, are considered. Besides the peak pressure value, effects of duration time correlated with natural frequencies are thought to be the important parameters.

Development of Design Charts to Estimate Member Forces on Basement Wall (지하벽체의 최대부재력 산정을 위한 차트의 개발)

  • Kim, Young-Chan;Kim, Ju-Bum
    • Journal of the Korean Society of Safety
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    • v.27 no.3
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    • pp.104-110
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    • 2012
  • It is a common practice to design basement walls acting as a one-way slab or plate with idealized boundary conditions, resulting in potentially inefficient design. The walls are often supported by buttress columns and side walls in the vertical direction, thereby acting as a two-way slab. In this study, structural behavior of single-story, three-span basement wall subjected to lateral soil pressure was investigated. Three dimensional finite element analyses were conducted to determine the force distribution on the wall. Based on the numerical studies, a regression analysis was carried out to determine the design values of moments in vertical and horizontal directions as well as shear forces on the wall and design charts are developed. The proposed design method with accompanying design charts would enable practicing engineers to estimate member forces on the wall for preliminary design purpose without resorting to finite element analysis. Numerical examples demonstrated the applicability of the proposed method.

A Study on the Formativeness of Russian Constructivism in Modern Fashion (현대 패션에 나타난 러시아 구성주의의 조형성에 관한 연구)

  • Sohn, Ho-Young;Kan, Ho-Sup
    • Journal of the Korean Society of Costume
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    • v.61 no.10
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    • pp.1-15
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    • 2011
  • Constructivism is an avant-garde movement that began in 20th-century Russia, which rapidly turned into an industrial society. This was one of the most experimental art movements, that wanted to be at the center of social and political-ideological change as it pursued a unique style, which portrayed the true essence of art and humanity. Russian constructivism greatly influenced modern fashion and suggested a new artistic standard. First, the artistic elements of Russian constructivism include photo montages, geometrical structures, color abstraction, and an asymmetrical order, through which the ideals of the Russian Revolution were substantiated, idealized, and materialized into an artistic form. Second, the different forms of Russian constructivism have various artistic characteristics such as popularity, spatiality, structuralism, decorativeness, and mobility, which were then expressed in modern fashion elaborated below. This study intends to reconstruct the meaning of Russian formalism and reflect it on fashion; thereby reconsidering the characteristics and the meaning of Russian constructivism in the context of today's fashion. This will broaden the meaning of constructivism and suggest a new direction for modern fashion.

Study on the micro-scale simulation of wind field over complex terrain by RAMS/FLUENT modeling system

  • Li, Lei;Zhang, Li-Jie;Zhang, Ning;Hu, Fei;Jiang, Yin;Xuan, Chun-Yi;Jiang, Wei-Mei
    • Wind and Structures
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    • v.13 no.6
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    • pp.519-528
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    • 2010
  • A meteorological model, RAMS, and a commercial computational fluid dynamics (CFD) model, FLUENT are combined as a one-way off-line nested modeling system, namely, RAMS/FLUENT system. The system is experimentally applied in the wind simulation over a complex terrain, with which numerical simulations of wind field over Foyeding weather station located in the northwest mountainous area of Beijing metropolis are performed. The results show that the method of combining a meteorological model and a CFD model as a modeling system is reasonable. In RAMS/FLUENT system, more realistic boundary conditions are provided for FLUENT rather than idealized vertical wind profiles, and the finite volume method (FVM) of FLUENT ensures the capability of the modeling system on describing complex terrain in the simulation. Thus, RAMS/FLUENT can provide fine-scale realistic wind data over complex terrains.

Free vibration analysis of tall buildings with outrigger-belt truss system

  • Malekinejad, Mohsen;Rahgozar, Reza
    • Earthquakes and Structures
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    • v.2 no.1
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    • pp.89-107
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    • 2011
  • In this paper a simple mathematical model is presented for estimating the natural frequencies and corresponding mode shapes of a tall building with outrigger-belt truss system. For this purposes an equivalent continuum system is analyzed in which a tall building structure is replaced by an idealized cantilever continuum beam representing the structural characteristics. The equivalent system is comprised of a cantilever shear beam in parallel to a cantilever flexural beam that is constrained by a rotational spring at outrigger-belt truss location. The mathematical modeling and the derivation of the equation of motion are given for the cantilevers with identically paralleled and rotational spring. The equation of motion and the associated boundary conditions are analytically obtained by using Hamilton's variational principle. After obtaining non-trivial solution of the eigensystem, the resulting is used to determine the natural frequencies and associated mode shapes of free vibration analysis. A numerical example for a 40 story tall building has been solved with proposed method and finite element method. The results of the proposed mathematical model have good adaptation with those obtained from finite element analysis. Proposed model is practically suitable for quick evaluations during the preliminary design stages.