• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.351-362
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• 1999

Damage detection methods which utilize the change in dynamic characteristics are very hard to apply to large civil structures since local damage hardly affects global dynamic characteristics. But, if there is a very important and critical member and we focus only on the local behavior of it, it would be possible to detect damage from the change in local dynamic characteristics, such as natural frequencies and mode shapes .In this study, the cable anchorage part of a cable-stayed bridge under construction is modeled and analyzed by commercial finite element program, ABAQUS. It has both welding and bolting connections with a cable and a stiffening plate, and has a possible high stress concentration portions in it. Several damage scenarios such as crack through the welding or crack through the bolting connection are examined. The result shows that the local natural frequencies of the damaged member decrease up to 16% compared with that of the undamaged member. It is concluded that there is quite a high feasibility that the damage of the cable anchorage can be detected by measuring local dynamic characteristics.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.57-62
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• 2011

The effects of swirl chamber's diameter and length on injector's dynamic characteristics were investigated through an experimental study. A mechanical pulsator was installed in front of the manifold of a swirl injector which produces pressure oscillations in the feed line. Pressure in the manifold, liquid film thickness in the orifice and the pressure in the orifice were measured in order to understand the dynamic characteristic of the simplex swirl injector with varying geometry. A direct pressure measuring method (DPMM) was used to calculate the axial velocity of the propellant in the orifice and the mass flow rate through the orifice. These measured and calculated values were analyzed to observe the amplitude and phase differences between the input value in the manifold and the output values in the orifice. As a result, a phase-amplitude diagram was obtained which exhibits the injector's response to certain pressure fluctuation inputs. The mass flow rate was calculated by the DPMM and measured directly through the actual injection. The effect of mean manifold pressure change was insignificant with the frequency range of manifold pressure oscillation used in this experiment. Mass flow rate was measured with the variation of injector's geometries and amplitude of the mass flow rate was observed with geometry and pulsation frequency variation. It was confirmed that the swirl chamber diameter and length affect an injector's dynamic characteristics. Furthermore, the direction of geometry change for achieving dynamic stability in the injector was suggested.

• PNF and Movement
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• v.7 no.2
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• pp.11-20
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• 2009

Purpose : The purpose of this study is to find out which method is efficient to enhance the flexibility of lower back between PNF(Proprioceptive Neuromuscular Facilitation), static and dynamic stretching. Methods : Subjects were 30 young people between the ages 17 and 19. They were randomly divided into three groups; static group(n=10) performed a static stretching, dynamic group(n=10) performed a dynamic stretching, and PNF group(n=10) performed a PNF stretching. Intervention was provided 5 days per week for 4 weeks. For each case, Trunk flexion forward, trunk flexion backward, trunk left lateral bending, trunk right lateral bending, trunk flexion forward a measuring instrument and tapeline were performed to measured the flexibility of lower back at different times(before starting the exercise, after 4 weeks). Results : The results of the study reveal that the lower back flexibility was a statistically significant difference in all groups(p<.05). There was statistically significant difference between PNF group and static group, PNF group and dynamic group. Conclusion : The finding indicated that PNF may be preferred technique for improving flexibility, and that flexibility training results in an increased consistency of flexibility scores.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.309-321
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• 1997

The prediction of the dynamic response of a bridge resulting from passing vehicles across the span is a significant problem in bridge design. In this paper. the static and dynamic experiments are performed to understand the dynamic behavior of an actual two-span steel plate girder bridge. The road surface roughness of the roadway and bridge deck is directly measured by Intelligent Total Station. Numerical scheme to obtain the dynamic responses of the bridges in consideration of measuring road surface roughness and 3-D vehicle model is also presented. The bridge and vehicle are modeled as 3-D bridge and vehicle model, respectively. The main girder and concrete deck are modeled as beam and shell elements, respectively and rigid link is used for the structure between main girder and concrete deck. Bridge-vehicle interaction equations are derived and the impact factors of the responses for different vehicle speeds are calculated and compared with those predicted by several foreign specifications.

• The Journal of Korean Physical Therapy
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• v.32 no.2
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• pp.88-93
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• 2020

Purpose: This study examined the inter-rater reliability of cervical proprioception, dynamic balance ability, and ankle dorsiflexion range of motion using STARmat^®, which is a practical clinical tool that can provide practitioners and patients with quantitative and qualitative results. Methods: Thirty healthy young subjects were enrolled in this study, and two well-trained physical therapists participated as a tester. Two testers measured the cervical joint position error at the starting position after neck flexion, extension, side bending, and rotation; three dynamic balance tests, including anterior excursion, anterior reaching with single leg balance, and posterior diagonal excursion; and ankle dorsiflexion range of motion using STARmat^®. The intra-class correlation coefficient (ICC) was used to determine the inter-rater reliability of the tests. Results: The inter-rater reliability for the cervical proprioception ranged from moderate to good (0.66 to 0.83), particularly for flexion (0.82), extension (0.70), right side bending (0.73), left side bending (0.71), right rotation (0.83), and left rotation (0.66). For the dynamic balance, the inter-rater reliability ranged from good to excellent (0.87 to 0.91), particularly for anterior excursion (0.86), posterior diagonal excursion (0.87 to 0.89), and anterior reaching with a single leg balance (0.90 to 0.91). In addition, for the ankle dorsiflexion range of motion, the ICC for the inter-rater reliability ranged from 0.95 to 0.96. Conclusion: STARmat^® is a reliable tool for measuring cervical proprioception, dynamic balance tests, and ankle dorsiflexion range of motion in healthy young adults.

• The Journal of Advanced Prosthodontics
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• v.5 no.1
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• pp.21-28
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• 2013

PURPOSE. This study examined the effects of the abutment types and dynamic loading on the stability of implant prostheses with three types of implant abutments prepared using different fabrication methods by measuring removal torque both before and after dynamic loading. MATERIALS AND METHODS. Three groups of abutments were produced using different types of fabrication methods; stock abutment, gold cast abutment, and CAD/CAM custom abutment. A customized jig was fabricated to apply the load at $30^{\circ}$ to the long axis. The implant fixtures were fixed to the jig, and connected to the abutments with a 30 Ncm tightening torque. A sine curved dynamic load was applied for $10^5$ cycles between 25 and 250 N at 14 Hz. Removal torque before loading and after loading were evaluated. The SPSS was used for statistical analysis of the results. A Kruskal-Wallis test was performed to compare screw loosening between the abutment systems. A Wilcoxon signed-rank test was performed to compare screw loosening between before and after loading in each group (${\alpha}$=0.05). RESULTS. Removal torque value before loading and after loading was the highest in stock abutment, which was then followed by gold cast abutment and CAD/CAM custom abutment, but there were no significant differences. CONCLUSION. The abutment types did not have a significant influence on short term screw loosening. On the other hand, after $10^5$ cycles dynamic loading, CAD/CAM custom abutment affected the initial screw loosening, but stock abutment and gold cast abutment did not.

• Computers and Concrete
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• v.20 no.4
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• pp.491-502
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• 2017

In this research, the application of ultrasonic pulse velocity (UPV) test as a nondestructive method for estimating some of the mechanical and dynamic properties of reactive powder concrete (RPC) containing steel and polyvinyl alcohol (PVA) fibers, as well as their combination was explored. In doing so, ten different mix designs were prepared in 19 experimental groups of specimens containing three different volume contents of steel fibers (i.e., 1, 2, and 3 %) and PVA fibers (i.e., 0.25, 0.5, and 0.75 %), as well as hybrid fibers (i.e., 0.25-0.75, 0.5-0.5, and 0.75-0.25 %). The specimens in these groups were prepared under the two curing regimes of normal and heat treatment. Moreover, the UPV test results were employed to estimate the compressive strength, dynamic modulus, shear modulus, and Poisson's ratio of the RPC concrete and to investigate the quality level of the used concrete. At the end, the effect of the specimen shape and in fact the measuring distance length on the UPV results was explored. The results of this research suggest that the steel fiber-containing RPC specimens demonstrate the highest level of ultrasonic pulse velocity as well as the highest values of the mechanical and dynamic properties. Moreover, heat treatment has a positive effect on the density, UPV, dynamic modulus, Poisson's ratio, and compressive strength of the RPC specimens, whereas it leads to a negligible increase or decrease in the shear modulus and static modulus of elasticity. Furthermore, the specimen shape affects the UPV of fiber-lacking specimens while negligibly affecting that of fiber-reinforced specimens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.129-138
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• 2004

In this study we determine a dynamic analysis of the existing two-span prestressed concrete box girder bridge subjected to moving vehicle loads using the experimental measurements. The moving loads applied in this paper are classified as general travelling, suddenly brake, continuous travelling, reversely travelling and reversely travelling impact loads for increasing velocities. For each travelling load, we search dynamic behaviors and characteristic in various measuring point of box girder section. In addition, the three-dimensional numerical results analyzed by the developed finite element program using flat shell element with six degrees of freedom per a node are compared with the measured experimental data. Dynamic behaviors caused impact loads by suddenly braking, reversely travelling, are bigger than by general travelling in box girder. Three-dimensional numerical results are better than one-dimensional results.

• Physical Therapy Rehabilitation Science
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• v.3 no.2
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• pp.125-133
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• 2014

Objective: The aim of this study is to investigate the effect of patellar taping on balance and gait abilities in chronic stroke patients. Design: Randomized placebo-controlled trial. Methods: Thirty chronic stroke patients who have been diagnosed at least six months or before were recruited from R hospital. These study subjects were randomized to the experimental group (n=15) or placebo group (n=15). In the experimental group, patellar taping was applied while for the placebo group, placebo taping was applied. The Balance System SD was used for measuring dynamic standing balance in these two groups. In addition, the GAITRite (CIR System Inc.) system was utilized for calculating gait performance in these patients. Results: After application of taping, the patellar taping group showed a significant decrease in dynamic standing balance in their sway area (p<0.05). However, in the placebo group, there was no significant difference in dynamic standing balance ability and gait ability before and after application of taping. Comparison of the patellar taping group and placebo group showed significant differences in dynamic standing balance ability and gait performance (p<0.05). Conclusions: From the results of this study, it appears that application of patellar taping in chronic stroke patients significantly improved dynamic standing balance ability and gait ability in these patients. Based on these results, patellar taping is thought to be useful in real clinical settings where there are many chronic patients who are in need of improvement in their balance and gait ability.

• Physical Therapy Korea
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• v.29 no.4
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• pp.274-281
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• 2022

Background: The range of motion (ROM) and balance ability of the ankle joint affect the stability of the ankle and prevent injuries or hurts from falling. In the clinical tests conducted recently, the floss band is widely used to enhance the range of joint motion and exercise performance, and there are many studies that have applied it to ankle joint increasing dorsi flexion (DF) angle. Objects: This study compared the effects on the range of ankle motion and static/dynamic balance ability of the ankle through three conditions (before floss band intervention, after floss band intervention, and after active exercise intervention) for adults. Methods: One intervention between floss band and active exercise was applied randomly and another intervention was applied the next day. After each intervention, the ROM of the ankle joints and the static balance was checked by measuring conducting one leg test. And the dynamic balance was checked by conducting a Y-balance test. Results: In the case of DF, the range of joint motion showed a significant increase after floss band intervention compared to before floss band intervention (p < 0.05). Static balance ability showed a significant increase after the intervention of floss band and active exercise compared to before the intervention of floss band (p < 0.05). The dynamic balance ability showed a significant increase after the intervention of the floss band compared to before intervention of the floss band and after active exercise intervention (p < 0.05). Conclusion: Based on these results, it was confirmed that the application of floss band to the ankle joint increases DF and improves the static and dynamic balance ability. Based on this fact, we propose the application of a floss band as an intervention method to improve the ROM of the ankle joint and improve the stability of the ankle in clinical field.