• 제목/요약/키워드: Post tension

검색결과 288건 처리시간 0.026초

Advanced Idealized Structural Units Considering Excessive Tension-Deformation Effects

  • Paik, Jeom-Kee
    • Journal of Hydrospace Technology
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    • 제1권1호
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    • pp.125-145
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    • 1995
  • In this paper, three kinds of the existing idealized structural units, namely the idealized beam-column units the idealized unstiffened plate unit and the idealized stiffened plate unit are expanded to deal with the excessive tension-deformation effects. A simplified mechanical model far the stress-strain relationship of steel members under tensile load is suggested. The 1/3-scale hull model for a leander class frigate under sagging moment tested by Dow is analyzed, and it is shown that the excessive tension-deformation is a significant factor affecting the progressive collapse behavior, particularly in the post-collapse range.

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롤투롤 시스템에서의 비 접촉 이송 시스템을 위한 수학적 장력 모델에 관한 연구 (A study on the Mathematical Tension Model for a Non-contact Transfer of a Moving Web in R2R e-Printing Systems)

  • 이창우;김호준;강현규;신기현
    • 제어로봇시스템학회논문지
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    • 제15권9호
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    • pp.894-898
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    • 2009
  • In a post printing section of roll to roll printing systems, scratch problem is the major defects. The functional qualities such as conductivity, mobility could deteriorate because of the scratch defect. In general, the scratch of the printed pattern on the flexible substrate was induced from a contact between rolls and printed pattern in the post printing section. In this paper, for non-contacting transfer of a moving web, a mathematical tension model has been developed considering strain due to air floatation and the proposed mode has been validated by numerical simulation. Additionally, the correlation between floatation height and speed compensation to control the tension and register are investigated. On the basis of the proposed model, a guide line of speed control in R2R printing system is presented to guarantee the non-contact between rolls and R2R printed pattern on the flexible substrate.

긴장력이 도입된 곡면벽체의 충돌저항성능 수치해석평가 (Assessment of Impact Resistance Performance of Post-tensioned Curved Wall using Numerical Impact Analysis)

  • 정철헌;이정휘;정래영;유태용
    • 한국전산구조공학회논문집
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    • 제29권2호
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    • pp.161-167
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    • 2016
  • 이 논문에서는 벽체의 형상(평면벽체, 곡면벽체) 및 벽체에 도입된 긴장력이 충돌저항성능에 미치는 영향을 수치해석적 기법을 사용하여 평가하고자 하였다. 벽체의 곡률 및 긴장력 도입률을 변수로 총 12 케이스의 충돌해석을 수행하였으며, 충돌체로는 상용 민항기엔진의 3차원 상세모델을 사용하였다. 충돌저항성능을 평가하기 위해 관입깊이와 벽체 중앙부 후면의 최대 변위를 비교하였다. 긴장력의 도입에 의해 관입깊이는 약 60~80% 수준으로 감소하는 것으로 나타났으나, 후면 변위는 큰 차이가 나타나지 않았으며, 벽체 형상에 따른 차이는 상대적으로 크지 않은 것으로 나타났다.

Flexural behavior model for post-tensioned concrete members with unbonded tendons

  • Kim, Kang Su;Lee, Deuck Hang
    • Computers and Concrete
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    • 제10권3호
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    • pp.241-258
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    • 2012
  • The need for long-span members increases gradually in recent years, which makes issues not only on ultimate strength but also on excessive deflection of horizontal members important. In building structures, the post-tension methods with unbonded tendons are often used for long-span members to solve deflection problems. Previous studies on prestressed flexural members with unbonded tendons, however, were mostly focused on the ultimate strength. For this reason, their approaches are either impossible or very difficult to be implemented for serviceability check such as deflection, tendons stress, etc. Therefore, this study proposed a flexural behavior model for post-tensioned members with unbonded tendons that can predict the initial behavior, before and after cracking, service load behavior and ultimate strength. The applicability and accuracy of the proposed model were also verified by comparing with various types of test results including internally and externally post-tensioned members, a wide range of reinforcement ratios and different loading patterns. The comparison showed that the proposed model very accurately estimated both the flexural behavior and strength for these members. Particularly, the proposed model well reflected the effect of various loading patterns, and also provided good estimation on the flexural behavior of excessively reinforced members that could often occur during reinforcing work.

원심성 저항운동으로 유발한 지연성근육통이 고유수용성감각, 근력 및 근피로도에 미치는 영향 (Effects of the Eccentric Exercise Inuced Delayed Muscle Soreness on Proprioception, Muscle Strength and Muscle Fatigue)

  • 최규환;남상남
    • The Journal of Korean Physical Therapy
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    • 제16권3호
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    • pp.176-191
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    • 2004
  • The purpose of this study was to find the effects of the eccentric exercise induced delayed muscle soreness on proprioception, muscle strength, muscle fatigue, and muscle pain of the elbow flexor muscles. Thirty one healthy male subjects were participated in this study. Before resisted eccentric exercise of the elbow flexors and immediately and at 1, 3, 5, and 7 days post-exercise, pain threshold, proprioception, tension tracking, initial median frequency, and fatigue index were measured. Pain pressure threshold and visual analog scale (VAS) was used to measure muscle pain. Proprioception of the elbow joint was measured by using 3 dimension motion analysis system. Maximum isometric contraction was measured by using digital tensiometer. Electromyography and power spectrum analysis was used to measure initial median frequency (IMF) and fatigue index (FI). Immediately post-exercise, a significant decrease pain threshold was observed that continued to 5 days post-exercise. VAS score was significantly increased at 1 and 3 days post-exercise compared to that of immediately post-exercise. Maximum isometric contraction, IMF, tension tracking ability of the exercised elbow joint were significantly decreased at 1, 3, and 5 days post-exercise compared to that of pre-exercise. FI was significantly increased at 1 and 3 days post-exercise compared that of pre-exercise. Proprioception sense of exercised elbow joint was significantly decreased immediately and at 1, 3, and 5 days post-exercise compared to that of pre-exercise. Proprioception sense of the contralateral elbow joint was significantly decreased immediately post-exercise compared to that of pre-exercise. However, proprioception sense that was measured in close chain kinematic position was not significantly difference between pre-exercise and post-exercise. These results could be useful to determine the resume time for exercising and participating sports activities.

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초음파기기를 이용한 맥상(脈象) 연구 (A Study on Pulse Pattern Using Ultrasonic Device)

  • 김희영;박정빈;금유정;여인금;엄동명;송지청
    • 대한한의학원전학회지
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    • 제34권2호
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    • pp.85-94
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    • 2021
  • Objectives : Pulse diagnosis is one of the main diagnostic methods of Korean Medicine that understands the patient's condition and illness by reading changes in the patient's pulse, which is described in terms of pulse condition While they are described in detail in medical texts, it is difficult to grasp their true nature, as the written descriptions fail to do justice to the experience of pulse taking it tries to convey. As a way to approach pulse condition the effect of the body's tension on the radial vein was measured using an ultrasonic device, after which the measured changes and how they could be reflected in pulse condition were studied. In other words, changes in the radial vein following induced tension were analyzed. Methods : 1) The thickness of the subject's radial vein was measured using a linear probe of an ultrasonic device[LOGIQ 5 Basic, GE, USA]. 2) Fatigue level was increased through artificial stimulation using the Gripmeter[ks-301, Lavisen, Korea]. 3) Thickness of the radial vein post tension induction was measured. 4) The results were analyzed with the Tukey test or paired t-test as post hoc tests. Results : Thickness of the radial vein of the subject pre- and post- Gripmeter stimulation decreased with significance. Conclusions : Constriction of the radial vein that happened after tension induction could be linked to the Tight Pulse[緊脈] that is related to patterns of contraction and pulling.

Application of magnetoelastic stress sensors in large steel cables

  • Wang, Guodun;Wang, Ming L.;Zhao, Yang;Chen, Yong;Sun, Bingnan
    • Smart Structures and Systems
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    • 제2권2호
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    • pp.155-169
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    • 2006
  • In this paper, the application of magnetoelasticity in static tension monitoring for large steel cables is discussed. Magnetoelastic (EM) stress sensors make contact-free tension monitoring possible for hanger cables and post-tensioned cables on suspension and cable-stayed bridges. By quantifying the correlation of magnetic relative permeability with tension and temperature, the EM sensors inspect the load levels in the steel cables. Cable tension monitoring on Qiangjiang (QJ) 4th Bridge demonstrates the reliability of the EM sensors.

강섬유보강 고강도 철근콘크리트 부재의 인장강성모델 개발 (Development of Tension Stiffening Models for Steel Fibrous High Strength Reinforced Concrete Members)

  • 홍창우;윤경구;이정호;박제선
    • 콘크리트학회논문집
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    • 제11권6호
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    • pp.35-46
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    • 1999
  • The steel fiber reinforced concrete may affect substantially to the tension stiffening at post cracking behavior. Even if several tension stiffening models exist, they are for plain and normal strength concrete. Thus, the development of tension stiffening models for steel fibrous high strength RC members are necessary at this time when steel fiber reinforced and high strength concretes are common in use. This paper presents tension stiffening effects from experimental results on direct tension members with the main variables such as concrete strength, concrete cover depth, steel fiber quantity and aspect ratio. The comparison of existing models against experimental results indicated that linear reduced model closely estimated the test results at normal strength level but overestimated at high strength level. Discontinuity stress reduced model underestimated at both strength levels. These existing models were not valid enough in applying at steel fibrous high strength concrete because they couldn't consider the concrete strength nor section area. Thus, new tension stiffening models for high strength and steel fiber reinforced concrete were proposed from the analysis of experimental results, considering concrete strength, rebar diameter, concrete cover depth, and steel fiber reinforcement.