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Effects of Partially Distributed Loads on Dynamic Response of Plane Parabolic Arch (부분분포하중이 평면 포물선아치의 동적응답에 마치는 영향)

  • Cho, Jin-Goo;Park, Keun-Soo
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.6
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    • pp.21-28
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    • 2004
  • This study aims to investigate the effects of partially distributed loads on the dynamic behaviour of steel parabolic arches by using the elasto-plastic finite element model based on the Von Mises yield criteria and the Prandtl-Reuss How rule. For this purpose, the vertical and the radial load conditions were considered as a distributed loading and the loading range is varied from 40% to 100% of arch span. Normal arch and arch with initial deflection were studied. The initial deflection of arch was assumed by the sinusoidal motile of ${\omega}_i\;=\;{\\omega}_O$ sin ($n{\pi}x/L$). Several numerical examples were tested considering symmetric initial deflection when the maximum initial deflection at the apex is fixed as L/1000. The analysis resluts showed that the maximum deflection at the apex of arch was occurred when 70% of arch span was loaded. The maximum deflection at the quarter point of arch span was occurred when 50% of arch span was loaded. It is known that the optimal rise to span ratio between 0.2 and 0.3 when the vertical or radial distributed load is applied. It is verified that the influence of initial deflection of radial load case is more serious than that of vertical load case.

Effect of Nonionic Surfactant Solutions on Wetting and Absorbancy of PET Fabric 1. Mixtures and Dilutions of Span 20 and Tween 20 (비이온계 계면활성제 수용액이 PET직물의 습윤특성에 미치는 영향 제1보 : Span 20과 Tween 20의 혼합계와 희석계)

  • 김천희
    • Journal of the Korean Society of Clothing and Textiles
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    • v.27 no.9_10
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    • pp.1153-1159
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    • 2003
  • The effects of changing aqueous solution properties by nonionic surfactants on wetting behavior and water retention properies of hydrophobic PET (polyethylene terephthalate) fabric were reported. The aqueous solution properties were diversified by mixing and diluting two nonionic surfactants, i.e., sorbitan monolaurate (Span 20) and polyoxyethylene(20) sorbitan monolaurate (Tween 20). The surface wetting properties ($cos{\theta}$) of PET fabric were greatly improved by adding $10^{-1}g/dl$ Tween 20 and further improved by mixing Span 20 to the system. The water retention properties (W) of PET fabric were also greatly increased by addition of $10^{-1}g/dl$ Tween 20. In diluted surfactant systems, the $cos{\theta}'s$ were increased with decreasing surface tension of aqueous liquids. The ratios of aqueous liquid retained in the pore structure to liquid retention capacity (W/H) were also increased with decreasing surface tension, however, W/H values were dramatically increased right after critical micelle concentration (cmc). The existence of micelles was important for the retention of aqueous liquids in the fabric. The critical surface tension of PET fabric used was found to be 28.7dyne/cm.

Static behavior of Kiewitt6 suspendome

  • Li, Kena;Huang, Dahai
    • Structural Engineering and Mechanics
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    • v.37 no.3
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    • pp.309-320
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    • 2011
  • As a new type of large-span space structure, suspendome is composited of the upper single-layer reticulated shell and the lower cable-strut system. It has better mechanical properties compared to single-layer reticulated shell, and the overall stiffness of suspendome structure increases greatly due to the prestress of cable. Consequently, it can cross a larger span reasonably, economically and grandly with high rigidity, good stability and simple construction. For a better assessment of the advantages of mechanical characteristic of suspendome quantitatively, the static behavior of Kiewitt6 suspendome was studied by using finite element method, and ADINA was the software application to implement the analysis. By studying a certain suspendome, the internal forces, deformation and support constrained forces of the structure were obtained in this paper. Furthermore, the influences of parameters including prestress, stay bar length, cross-sectional area and rise-to-span ratio were also discussed. The results show that the increase of prestress and vertical stay bar length can improve the stiffness of suspendome; Cross-sectional area has nearly no impact on the static behavior, and the rise-to-span ratio is the most sensitive parameter.

LIFE-SPAN SIMULATION AND DESIGN APPROACH FOR REINFORCED CONCRETE STRUCTURES

  • An, Xuehui;Maekawa, Koichi;Ishida, Tetsuya
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.3-17
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    • 2007
  • This paper provides an introduction to life-span simulation and numerical approach to support the performance design processes of reinforced concrete structures. An integrated computational system is proposed for life-span simulation of reinforced concrete. Conservation of moisture, carbon dioxide, oxygen, chloride, calcium and momentum is solved with hydration, carbonation, corrosion, ion dissolution. damage evolution and their thermodynamic/mechanical equilibrium. Coupled analysis of mass transport and damage mechanics associated with steel corrosion is presented for structural performance assessment of reinforced concrete. Multi-scale modeling of micro-pore formation and transport phenomena of moisture and ions are mutually linked for predicting the corrosion of reinforcement and volumetric changes. The interaction of crack propagation with corroded gel migration can also be simulated. Two finite element codes. multi-chemo physical simulation code (DuCOM) and nonlinear dynamic code of structural reinforced concrete (COM3) were combined together to form the integrated simulation system. This computational system was verified by the laboratory scale and large scale experiments of damaged reinforced concrete members under static loads, and has been applied to safety and serviceability assessment of existing structures. Based on the damage details predicted by the nonlinear finite element analytical system, the life-span-cost of RC structures including the original construction costs and the repairing costs for possible damage during the service life can be evaluated for design purpose.

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Minimum Thickness of Long Span RC Deck Slabs for Composite 2-girder Bridges Designed by KL-510 Load Model (KL-510 하중모형을 적용한 강합성 2거더교 RC 장지간 바닥판의 최소두께)

  • Park, Woo-Jin;Hwang, Hoon-Hee
    • Journal of the Korean Society of Safety
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    • v.29 no.3
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    • pp.72-78
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    • 2014
  • The minimum thickness of long-span deck slab is proposed by checking the limit state according to the Korean highway bridge design code(limit state design). Both minimizing thickness and ensuring safety of deck slab are important design factors to increase a competitive price of the long span deck slabs. The required thicknesses for satisfying flexural capacity, preventing punching shear failure and limiting deflection were calculated by considering KL-510 load model which has increased total load compared to DB 24 from 432 kN to 510 kN. The results of the required thickness for various limit states were compared to propose the minimum thickness as a function of span length of deck slabs. The proposed minimum thickness is influenced by satisfying flexural capacity and limiting deflection. It turns out to be similar compared to the results of the previous study by ultimate strength design method even if the live load model was increased in total weights.

The Compensation Effect of the Distorted WDM Signals Depending upon the Deviation of Residual Dispersion per Span (RDPS) in Dispersion-Managed Optical Transmission Links with the Specially Artificial Distributions of SMF Lengths and RDPS (SMF 길이와 RDPS가 특정하게 인위적으로 분포하는 분산 제어 링크에서 RDPS 편차에 따른 왜곡된 WDM 신호의 보상 효과)

  • Lee, Seong-Real
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.10a
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    • pp.964-966
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    • 2015
  • The effect of the deviations of single mode fiber lengths and residual dispersion per span (RDPS) on the compensation for the distorted WDM signals in the dispersion-managed optical links with the specially artificial distributions of the lengths of SMFs and RDPSs. The considered artificial distribution is following; the lengths of SMF and RDPSs between the adjacent fiber span are more descended in the half transmission section from transmitter to optical phase conjugator (OPC), and those are more ascended in the rest half transmission section from OPC to the receiver, as number of fiber spans are more increased.

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Nonlinear time-varying analysis algorithms for modeling the behavior of complex rigid long-span steel structures during construction processes

  • Tian, Li-Min;Hao, Ji-Ping
    • Steel and Composite Structures
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    • v.18 no.5
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    • pp.1197-1214
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    • 2015
  • There is a great difference in mechanical behavior between design model one-time loading and step-by-step construction process. This paper presents practical computational methods for simulating the structural behavior of long-span rigid steel structures during construction processes. It introduces the positioning principle of node rectification for installation which is especially suitable for rigid long-span steel structures. Novel improved nonlinear analytical methods, known as element birth and death of node rectification, are introduced based on several calculating methods, as well as a forward iteration of node rectification method. These methods proposed in this paper can solve the problem of element's 'floating' and can be easily incorporated in commercial finite element software. These proposed methods were eventually implemented in the computer simulation and analysis of the main stadium for the Universiade Sports Center during the construction process. The optimum construction scheme of the structure is determined by the improved algorithm and the computational results matched well with the measured values in the project, thus indicating that the novel nonlinear time-varying analysis approach is effective construction simulation of complex rigid long-span steel structures and provides useful reference for future design and construction.

A study of Aging and Life Span in Sasang Constitutional Medicine (노화와 수명에 관한 사상의학적 양생관에 대한 고찰)

  • Lee, Eui-Ju;Song, Il-Byung;Ko, Byung-Hee;Yoo, Jung-Hee
    • Journal of Sasang Constitutional Medicine
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    • v.14 no.3
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    • pp.7-16
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    • 2002
  • Purpose The goal of this study tried to provide aging and life span in Sasang Constitutional Medicine. Methods It was researched Master Dong-Mu's documentary records about aging and the life span represented by ${\ulcorner}$Dongyi Soose Bowon Sasang Chobongyun${\lrcorner}$ and ${\ulcorner}$Dongyi Soose Bowon${\lrcorner}$ published in 1901. Results & conclusion 1. A principal of regimen according to Sasang Constitutional Medicine isn't medicational method but non-medicational method. There are control mind and upright oneself. 2. Dong-Mu's the views of the span of life represented by 'Inherent vitality' that a term means health promoting and forecasting length of the life. He also emphasizied a natural power of recovery from damaged vitality. 3. Greed is reduced one's lifetime. It is originated by bias for 'joy-anger -sorrow-pleasure'. The other example is 'Liquor-Sex-Property- Authority'. 4. The way of prolonging lifetime what managed small visceral intestines through constitutional upright oneself. This is found on pathology, care of health and constitutional 'Knowledge and Deed'.

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A study on the Residential Satisfaction and Maintenance Consciousness to the Life Span of Apartment (경년에 따른 공동주택 거주자의 주거환경 만족도 및 관리의식 조사연구)

  • Yoon, Chung-Sook;Shin, Soo-Young;Kim, Soo-Jeong
    • Proceeding of Spring/Autumn Annual Conference of KHA
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    • 2005.11a
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    • pp.43-49
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    • 2005
  • The purpose of this study was to provide the fundamental data for the gradual apartment management plan. Through the questionnaire survey, residential satisfactions and maintenance consciousness were investigated. As the result of statistic analysis, the residents' needs for improvement according to the life span of apartment communities were found out. And we can also compare the differences about maintenance consciousness to the life span of apartment. The major research findings are as follows. First, the satisfaction averages according to the life span of apartment communities were classified two groups, less than 10 years' and over than 10 years'. By the requirement for improvement according as the life span apartment communities, habitability factors was demanded in less tham 10 years' group and safety factors was required in over than 10 years' group, Second, dwellers have high preference about remodeling to reconstruction. Especially we have to pay attention to the result that positive consciousness of remodeling and long term reparative marked highly in the group which has the short elapsed years. These results represent the possibility gradual step-by-step remodeling. In other words, the object of remodeling is not only odeteriorated apartments but also new apartments to have short elapsed years.

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A Study on the Life Span Prediction of Railroad Wheels caused by Rolling Contact Fatigue (철도차륜의 구름접촉피로에 의한 수명예측에 관한 연구)

  • Chun, C.K.;Yang, J.S.;Park, S.J.;Yi, G.S.;Ma, Y.S.
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.6
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    • pp.1012-1020
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    • 2006
  • The crack that occurs on the wheels of railroad cars can be categorized into a surface crack that starts from the surface or a subsurface crack that starts from the inside and can be detrimental to safe railroad operations. Therefore, estimating the growth life span of this type of crack is very important. In this research, the stress distributions, displacements, and the growth-life spans of both surface cracks and subsurface cracks have been studied. By using the finite element analysis, especially in the life span prediction process, the stress conditions and the stress intensity factors of the crack tip have been discovered. The Paris formula has been used to analyze the growth-life span prediction.

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