• Title/Summary/Keyword: Pre-tension

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

  • Jung, Hwan-Mok;Woo, Jae-Won;Cho, Byung-Wook;Lee, Seong-Yeun
    • Proceeding of KASS Symposium
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    • 2008.05a
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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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Inelastic Nonlinear Analysis of Structures with Under -Tension System (언더텐션 시스템이 적용된 구조물의 비탄성 비선형 거동 해석)

  • Park, Duk-Kun;Lee, Jae-Hong
    • Journal of Korean Association for Spatial Structures
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    • v.9 no.2
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    • pp.91-97
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    • 2009
  • This study presents geometric nonlinear and material analysis of under-tension structure using Total Lagrangian and Updated Lagrangian method. In the regard, the under-tension system enables the load of upper part to carry to the end of beam by pre-tensional force in cable. The under-tension system on lower part of the structure is applied in order to reduce the deflection and size of member. This study is performed with conforming of the effect by pretension value in the cable and applying loading. Dead and Live loads are supposed to apply nodal on the top member. The member force and deflection of the structure are with MIDAS and ADINA.

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

  • 안철민;박정은
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.10 no.1
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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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3 Case Reports on Tension-type Headache Treated by Chuna manipulative Therapy (긴장성 두통에 대한 추나요법 치험 3례)

  • Won, Je-Hoon;Kim, Young-Jun;An, Hee-Duk;Woo, Chang-Hoon
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.10 no.1
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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.

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

  • Chae, Yun-Won;Lee, Hyun-Min
    • The Journal of Korean Physical Therapy
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    • v.21 no.4
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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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Effects of the Eccentric Exercise Inuced Delayed Muscle Soreness on Proprioception, Muscle Strength and Muscle Fatigue (원심성 저항운동으로 유발한 지연성근육통이 고유수용성감각, 근력 및 근피로도에 미치는 영향)

  • Choi Kyu-Hwan;Nam Sang-Nam
    • The Journal of Korean Physical Therapy
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    • v.16 no.3
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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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    • v.11 no.2
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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.

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

  • 한복규;홍건호;신영수;조하나
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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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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Effects of the Pre-strain on Mechanical Properties of the Solid-Phase Formed Thermoplastic Composite (고상성형된 열가소성 복합재료의 성형 변형률이 기계적 특성에 미치는 영향)

  • Lee, Jung-Hui;Jo, Hyeon-Cheol;Lee, Gyeong-Yeop
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.8
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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.

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

  • Kim, Min-Su;Lee, Ki-Hak;Kim, Seong-Beom;Lee, Sung-Min;Baek, Ki-Youl
    • Journal of Korean Association for Spatial Structures
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    • v.11 no.2
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    • pp.71-79
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    • 2011
  • Due to the self-equilibrium status of the cable system, the loss of the tensioning in the cable system results in other cables carrying larger tension forces than those initially calculated by structural engineers. Also, turn-buckle systems, which have been widely used to pre-tension and/or re-tension the cables, are limited to use for small cables and to provide a rough estimation for tension forces. In this study, the re-tensioning cable connection systems were developed to overcome the problems mentioned above. The main objective of the proposed system is to re-tension large cables and measure the exact amount of tension forces of the cable systems. This connection system is also combined with the wireless signal monitoring module so that engineers are able to measure the tension forces any place where the internet is available. This paper presents the development of the re-tensioning cable connection systems and experiment using the real-scale cable systems to verify the fe-tensioning and signal monitoring systems.