• 제목/요약/키워드: Pre-Tension

검색결과 225건 처리시간 0.035초

막구조물의 막장력 측정장치 개발에 관한 연구 (DEVEOPMENT OF MEASURING SYSTEM OF MEMBRANE STRESS FOR MEMBRANE STRUCTURE)

  • 정한목;우재원;조병욱;이성연
    • 한국공간구조학회:학술대회논문집
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    • 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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    • pp.171-178
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    • 2008
  • This paper is concerned with the development of a measurement system using field measuring device which will give the membrane stress of the membrane structures. Up to this point, several techniques on measurement of membrane stresses has been proposed and some have been used in the fields, but accuracy of the measured stresses to be far from reliable one. Such situation has not been changed until recent days, we do not have the measurement device on which we can depend. On top of that, due to the different properties in cross directions for material of the membrane, the stress in the warp direction is different from that in the fill one. A new method is proposed to measured membrane stresses in two different direction separately, where instead of membrane stresses directly, an external force perpendicular to the membrane to be applied. A portable device can measure the applied force and the displacement. A special testing bed to be fabricated to accommodate $50cm{\times}50$ manbrane specimen which can apply 5 ton load in two orthogonal direction. A special device using push-pull gage was developed. To measure the membrane stresses in warp and fill direction separately, a different length of the tips are used. The measuring device which can called tension meter, can be calibrated on the testing bed, and optimized the length and shape of tip.

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언더텐션 시스템이 적용된 구조물의 비탄성 비선형 거동 해석 (Inelastic Nonlinear Analysis of Structures with Under -Tension System)

  • 박덕근;이재홍
    • 한국공간구조학회논문집
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    • 제9권2호
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    • pp.91-97
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    • 2009
  • 본 논문은 Total Lagrangian(TL)과 Updated Lagrangian(UL)을 사용하여 구조물 하부에 케이블을 연결하고, 그 케이블에 인장력을 가하여 구조물의 처짐을 제어하는 언더텐션 시스템에 있어서 케이블의 인장력에 따른 구조물의 처짐 거동의 변화와 각 부재력을 비교함으로서 언더텐션 시스템의 효율성을 검증하는데 있다. 일반적인 빔과 거더로 이루어진 구조와는 달리 언더텐션 시스템에서는 상부에서는 하중을 하부 케이블의 인장력을 이용하여 그 하중을 양 단부로 전달하게 된다. 언더텐션 시스템은 스트럿의 개수와 길이, 케이블의 초기 인장력의 크기에 따라서 그 효과가 다르게 나타날 수 있다. 또한 케이블이 설치된 장스팬 구조의 경우, 그 거동에 있어서 비선형성적 거동이 크게 나타나게 된다. 따라서 본 논문에서는 선형과 비선형해석 결과를 비교함으로써 비선형해석의 필요성에 대하여 논의하고자 한다.

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애성환자에 있어서 잘못된 발성습관에 관한 연구 (The Study of Faulty Vocal Habits in Patients with Hoarsenes)

  • 안철민;박정은
    • 대한후두음성언어의학회지
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    • 제10권1호
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    • pp.12-16
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    • 1999
  • Background and Objectives : The common cause of voice disorders may be bad habits of phonation. faulty vocal habits might aggravate the voice disorder or make the dysphonia. Authors thought the analysis of faulty vocal habits might help to evaluate the causes and to choose the treatment methods in patients with dysphonia. Authors studied to evaluate which vocal habits were used in patients with dysphonia. Materials and Methods : Patients with dysphonia(N= 32) and person without dysphonia(N=20) were evaluated through pre-evaluation test by otolaryngologist and SLP. All subjects were evaluated accordingly Posture of body, expansion of cervical vein, excessive movements of thyroide prominence, position of tongue, tension of lower lip, tension of jaw, breathing pattern related with phonation. Results : In dysphonia group, we found 23 cases with tension of jaw, 15 cases with expansion of cervical vein, 7 cases with bad position of tongue, 3 cases with excessive movement of thyroid prominence and a lot of cases with bad breathing Pattern on Phonation. In control group, only 3 cases with bad position of tongue, 2 cases with tension of lower lip, 1 case with tension of jaw were found. Conclusions : More faulty vocal habits were found in dysphonia group. Authors thought faulty vocal habits could be the cause of dysphonia and aggravate the dysphonia and the control of vocal habits would be very important in patients with dysphonia.

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긴장성 두통에 대한 추나요법 치험 3례 (3 Case Reports on Tension-type Headache Treated by Chuna manipulative Therapy)

  • 원제훈;김영준;안희덕;우창훈
    • 척추신경추나의학회지
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    • 제10권1호
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    • pp.97-106
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    • 2015
  • Objectives: The Purpose of this study is to report three cases on tension-type headache treated by Chuna manipulative therapy. Methods: Three patients diagnosed tension-type headache were treated with Chuna manipulative therapy only. To evaluate effect of treatment, visual analogue scale(VAS) and headache impact test(HIT) were used. We checked VAS and HIT score three times(pretreatment, post-treatment, follow-up). An interval among each evaluation time is 4 weeks. Results: At post-treatment evaluation, VAS and HIT score declined significantly compared with pre-treatment. At follow-up evaluation, the pain did not increased. Conclusions: These results suggests that Chuna manipulative therapy may be effective for tension-type headache.

긴장성 두통에 대한 두개경부 운동의 효과 (The Effect of Craniocervical Exercise on Tension-Type Headache)

  • 채윤원;이현민
    • The Journal of Korean Physical Therapy
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    • 제21권4호
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    • pp.9-16
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    • 2009
  • Purpose: This study was done to assess the effect of changes in forward head posture (FHP), neck mobility and headache clinical parameters on episodic tension-type headache (ETTH) and chronic tension-type headache (CTTH) who did craniocervial exercises. Methods: Twelve CTTH subjects and twelve ETTH subjects were studied. Side-view pictures of subjects were taken in both sitting and standing positions, in order to assess FHP by measuring the craniovertebral angle. Cervical range of motion (CROM) was employed to measure cervical mobility. A headache diary was kept to assess headache intensity, frequency, and duration. All subjects did three types of craniocervical exercise over 8 weeks. Measurements were done at pre-treatment, and at 4 and 8 weeks post-treatment. Results: Forward head posture and headache-related clinical parameters showed a significant improvement after craniocervical exercise (p<0.05). Flexion/extension and left/right rotation of CROM was significantly increased after the intervention (p<0.05), whereas changes in left/right bending did not reach statistical significance. Conclusion: This study indicates that craniocervical exercise may be effective in the management of tension-type headache.

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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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Numerical analysis of thermal and composite stresses in pre-stressed concrete pavements

  • Nejad, Fereidoon Moghadas;Ghafari, Sepehr;Afandizadeh, Shahriar
    • Computers and Concrete
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    • 제11권2호
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    • pp.169-182
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    • 2013
  • One of the major benefits of the pre-stressed concrete pavements is the omission of tension in concrete that results in a reduction of cracks in the concrete slabs. Therefore, the life of the pavement is increased as the thickness of the slabs is reduced. One of the most important issues in dealing with the prestressed concrete pavement is determination of the magnitude of the pre-stress. Three dimensional finite element analyses are conducted in this research to study the pre-stress under various load (Boeing 777) and thermal gradient combinations. The model was also analyzed under temperature gradients without the presence of traffic loading and the induced stresses were compared with those from theoretical relationships. It was seen that the theoretical relationships result in conservative values for the stress.

재하상태에 따른 강판보강공법의 휨 보강효과 (Flexural Rehabilitation Effect of Pre-loaded RC Beams Strengthened by Steel Plate)

  • 한복규;홍건호;신영수;조하나
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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    • pp.701-704
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    • 1999
  • The purpose of this study was to investigate the effectiveness of the flexural rehabilitation of the pre-loaded reinforced concrete beams strengthened by the steel plate. Main test parameters were the existence and the magnitude of the pre-loading at the flexural of rehabilitation and the tensile reinforcement ratio of the specimens. Seven beam specimens were tested to investigate the effectiveness of the rehabilitation method. Test results showed that the ultimate load capacities of the pre-loaded specimens were higher than not-pre-loaded specimens at the rehabilitation. The cause of the pharameter was analyzed if is suggested that the bond failure between the concrete and the strengthening steel plate occured prior to the yielding of the tension reinforcement. The member flexural stiffnesses, were similar regardless of the load conditions at retrofit and failure modes showed brittle aspect caused by rip-off failure.

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고상성형된 열가소성 복합재료의 성형 변형률이 기계적 특성에 미치는 영향 (Effects of the Pre-strain on Mechanical Properties of the Solid-Phase Formed Thermoplastic Composite)

  • 이중희;조현철;이경엽
    • 대한기계학회논문집A
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    • 제25권8호
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    • pp.1220-1226
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    • 2001
  • This study investigates the effects of the pre-strain level on mechanical properties of the solid-phase formed thermoplastic composite. A uniaxial solid-phase forming was performed at the temperature of 125$\^{C}$ and at the constant cross-head speed of 3mm/sec. The composite sheet was formed to various pre-strain levels of 10%, 20%, and 30%. Tension, flexural, and impact tests were carried out to characterize the material properties of a solid-phase formed part. Tensile and flexural strengths decreased with increasing the pre-strain level, while impact strength increased. Various microstructures of the formed part explained the above material behavior.

재긴장과 무선 모니터링이 가능한 유압식 케이블 접합부시스템의 실험에 대한 연구 (Experimental study of Hydraulic Cable Connection Systems with Re-tensioning and Wireless Monitoring)

  • 김민수;이기학;김성범;이성민;백기열
    • 한국공간구조학회논문집
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    • 제11권2호
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    • pp.71-79
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    • 2011
  • 케이블 구조시스템의 경우 자기 평형 상태를 유지하기 때문에 장력이 손실된 특정 케이블을 재긴장을 하지 않으면 구조엔지니어가 요구한 하중보다 더 큰 하중이 다른 케이블에 전달되어 손상을 야기 할 수 있다. 또한, 턴버클을 이용한 재긴장 방법이 기존에 널리 적용되고 있지만 정확한 장력조절과 대구경 케이블에는 적절하지 못하고 인장재의 하중의 크기를 측정하는 것이 어렵다. 따라서 효과적으로 재긴장 할 수 있는 유압식 볼팅 접합부를 개발하고 인장력을 실시간으로 확인할 수 있는 모니터링 시스템을 적용하였다. 본 논문에서는 개발된 시스템의 현장 적용성 실험과 결과를 제시하였다.