• Corrosion Science and Technology
• /
• v.11 no.4
• /
• pp.129-134
• /
• 2012

UT(Ultrasonic Test), one of the non-destructive tests, is the most common thickness measurement method for evaluating the wear rate in NPPs(Nuclear Power Plants). UT is used widely because it is easy and safe for use. However some amount of error inevitably occurs in attempting to measure the thickness. The error, that could make the thickness data thicker or thinner, may affect estimation of wear rate in pipes. NPPs are composed of a lot of pipes and components. Some of them are tested to check the current status during RFO(Re-Fueling Outage). Reliability analysis of UT is essential for evaluating pipe wear rate and establishing the long-term management plan in NPPs. This paper reviewed the cause of error occurrence and presented the UT data reliability analysis method. Also, this paper shows the application result of reliability analysis to the UT data acquired in NPPs.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.4 no.2
• /
• pp.40-45
• /
• 2008

There exist many types of pipe and component fatigue through vibrations, thermal fatigues or shifting. In some cases of thermal stratification/thermal fatigue, pipes & components are receiving thermal stress by means of material expansion and shrinkage by continuous thermal repetitive variation. Small cracks initially occur on the inside surface by thermal stress. These cracks grow in depth the pipe wall and finally come to a rupture. Pipe parts of susceptibility to thermal stratification and thermal fatigue are now being examined by conventional UT(ultrasonic test) as volumetric examination. It is difficult to fully satisfy the code & standards requirements because 3" weldolet weldments of RCS 16" pipe to 3" branch connection lines have complex structural shape. To solve the problems of conventional UT examination, we made a realistic mock-up and UT calibration block. We performed a simulation of phased array UT utilizing CIVA as NDE(Non-Destructive Examination) simulation software. Also we designed phased array UT transducer and wedge, optimal frequency by using simulation data. We performed phased array UT experiment through mock-up including artificial flaws(notch). The phased array UT technique is finally developed to improve the reliability of ultrasonic test at RCS 16" pipe to 3" branch connection weld.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.3
• /
• pp.11-20
• /
• 2020

PURPOSE: Excessive activity of the upper trapezius (UT) muscle contributes to a rounded shoulder posture (RSP) through abnormal rotation of the scapula that weakens the lower trapezius (LT) and serratus anterior (SA) muscles. This study compared the effects of two arm-lifting exercises with and without the use of a Thera-band on the activities of LT, SA, and UT muscles, and the LT/UT and SA/UT activity ratio in subjects with a rounded shoulder posture. METHODS: Sixteen subjects with RSP participated in this study. All subjects performed arm-lifting (AL), diagonal arm-lifting (DAL), arm lifting with isometric adduction (ALIA), and diagonal arm-lifting with isometric adduction (DALIA) exercises. The surface electromyography data, LT, SA, UT, and the LT/UT and SA/UT activity ratios were measured. A paired t-test was used to compare the differences between two arm-lifting exercises and two arm lifting with isometric adduction exercises. RESULTS: In ALIA and DALIA exercises, the UT muscle activity decreased significantly, whereas the LT/UT, SA/UT activity ratio increased significantly. The activity of SA muscle increased significantly more with DALIA than that with DAL. CONCLUSION: Arm-lifting exercises using a Thera-band can be implemented as an effective way to reduce the UT overactivity and increase the SA activity and LT/UT, SA/UT activity ratio in subjects with RSP.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.22 no.6
• /
• pp.649-658
• /
• 2002

As an attempt to further improve the reliability and effectiveness of ultrasonic testing (UT), a two-dimensional numerical simulator of UT was developed. The simulator models the wave medium (or test object) using the mass-spring lattice model (MSLM) that consists of mass-points and springs. Some previous simulation results, obtained by using MSLM, are briefly reviewed in this paper, for propagation, reflection, and scattering of ultrasonic waves. Next, the models of transmitting and receiving piezoelectric transducers are introduced with some numerical results, which is a main focus of this paper. The UT simulator, established by combining the transducer models with the MSLM, was used to simulate many UT setups. In this paper, two simple setups are considered as examples, and their simulated A-scan signals are discussed. The potential of the MSLM, transducer models, and the UT simulator developed in this study to be used in the actual UT is confirmed.

• Corrosion Science and Technology
• /
• v.13 no.2
• /
• pp.62-69
• /
• 2014

A huge number of carbon steel piping components installed in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), Cavitation, Flashing, and LDIE (Liquid Droplet Impingement Erosion). Those aging mechanisms can lead to thinning of the piping components. To manage the wall thinning degradation, most of utilities in the world predict the wall thinning rate based on the computational program such as CHECWORKS, COMSY, and BRT-CICERO, evaluate the UT (Ultrasonic Test) data, and determine next inspection timing, repair or replacement, if needed. There are several evaluation methods, such as band, blanket, and strip methods, commonly used for determining the wear of piping components from single UT inspection data. It has been identified that those single UT evaluation methods not only do not consider the manufacturing features of pipes, but also may exclude the data of the most thinned point when determining the representative wear rate of piping components. This paper describes a newly developed single UT evaluation method, E-Cross method, for solving above problems and introduces application examples for several pipes and elbows. It was identified that the E-Cross method using the length and width of UT data excluded the most thinned points appropriate as the single UT evaluation method for thinned piping components.

• Physical Therapy Korea
• /
• v.22 no.4
• /
• pp.17-26
• /
• 2015

The purpose of this study was to investigate the effects of visual electromyography (EMG) biofeedback on the EMG activity of the lower trapezius (LT), serratus anterior (SA), and upper trapezius (UT) muscles, the LT/UT and SA/UT EMG activity ratios, and the scapular upward rotation angle during scapular posterior tilting exercise (SPTE). Twenty-four subjects with round-shoulder posture participated in this study. The EMG activities of the LT, SA, and UT were collected during SPTE both without and with visual EMG biofeedback. The scapular upward rotation angle was measured at the baseline, after SPTE without visual EMG biofeedback, and after SPTE with visual EMG biofeedback. The LT, SA, and UT EMG activities, and the LT/UT and SA/UT EMG activity ratios were analyzed by paired t-test. The scapular upward rotation angle was statistically analyzed using one-way repeated analysis of variance. If a significant difference was found, a Bonferroni correction was performed (p=.05/3=.017). The EMG activities of LT and SA significantly increased, and the EMG activity of UT significantly decreased during SPTE with visual EMG biofeedback compared to SPTE without visual EMG biofeedback (p<.05). In addition, the LT/UT and SA/UT EMG activity ratios significantly increased during SPTE with visual EMG biofeedback compared to SPTE without visual EMG biofeedback (p<.05). Significant increases were found in the scapular upward rotation angle after SPTE without and with visual EMG biofeedback compared to baseline (p<.017), and no significant differences were observed in the scapular upward rotation angle between SPTE without and with visual EMG biofeedback. In conclusion, SPTE using visual EMG biofeedback may be an effective method for increasing LT and SA activities while reducing UT activity.

• Physical Therapy Korea
• /
• v.29 no.2
• /
• pp.165-170
• /
• 2022

Background: The serratus anterior (SA) muscle prevents scapular winging (SW) by stabilizing the medial border of the scapula during arm movement. The upper trapezius (UT) and lower trapezius (LT) muscles may compensate for the weak SA muscle in individuals with SW during shoulder flexion. However, there is no study to examine whether compensation by UT and LT occurs in individuals with SW. Objects: This study compared the muscle activities of UT, LT, and SA as well as the SA/UT activity ratio between individuals with and without SW during shoulder flexion with load. Methods: This study recruited 27 participants with SW (n = 14) and without SW (n = 13). Electromyography data of the SA, UT, and LT muscles and SA/UT activity ratio were recorded and analyzed during shoulder flexion with 25% load of the maximal shoulder flexion force. Independent t-test was used to compare the UT, LT, and SA muscle activities and SA/UT ratio between the groups with and without SW; statistical significance was set at α of 0.05. Results: SA activity was significantly lesser in the group with SW than in the group without SW. However, there were no significant differences in the UT and LT activities and SA/UT activity ratio between the two groups. Conclusion: The SA activity was lesser in the group with SW than in the group without SW with 25% load of the maximal shoulder flexion force, but there was no compensatory muscle activity of the UT and LT observed. Therefore, further studies are warranted to clarify the compensatory strategy of scapular stabilization in individuals with SW during shoulder flexion under other heavy load conditions.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.7 no.3
• /
• pp.40-47
• /
• 2011

KSNPs(Korea Standard Nuclear Power Plant) have been applied the break exclusion criteria to the high energy lines passing through containment penetration area to ensure that piping failures would not cause the loss of containment isolation function, and to reduce the resulting dynamic effects. Systems with the criteria are the Main Steam system, Feed Water system, Steam Generator Blowdown system, and Chemical & Volume Control system. In accordance with FSAR(Final Safety Analysis Report), a 100% volumetric examination by augmented in-service inspection of all pipe welds appled the break exclusion criteria is required for the break exclusion application piping. However, it is difficult to fully satisfy the requirements of inspection because 12", 8" and 6" weldolet weldments of Main Steam pipe line have complex structural shapes. To resolve the difficulty on the application of conventional UT(Ultrasonic Testing) technique, realistic mock-ups and UT calibration blocks were made. Simulations of conventional UT were performed utilizing CIVA, a commercial NDE(Nondestructive Examination) simulation software. Phased array UT experiments were performed through mock-up including artificial notch type flaws. A phased array UT technique is finally developed to improve the reliability of ultrasonic test at main steam line pipe to 12", 8" and 6" branch connection weld.

• Physical Therapy Korea
• /
• v.23 no.2
• /
• pp.57-66
• /
• 2016

Background: For the treatment of forward head posture (FHP) and forward shoulder posture, methods for strengthening scapular retractors and deep cervical flexors and stretching pectoralis and upper cervical extensors are generally used. No study has yet assessed whether suboccipital release (SR) followed by cranio-cervical flexion exercise (CCFE) (SR-CCFE) will result in a positive change in the shoulders and neck, showing a "downstream" effect. Objects: The purpose of this study was to investigate the immediate effects of SR-CCFE on craniovertebral angle (CVA), shoulder abduction range of motion (ROM), shoulder pain, and muscle activities of upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) and LT/UT and SA/UT muscle activity ratios during maximal shoulder abduction in subjects with FHP. Methods: In total, 19 subjects (7 males, 12 females) with FHP were recruited. The subject performed the fifth phase of CCFE immediately after receiving SR. CVA, shoulder abduction ROM, shoulder pain, muscle activities of UT, LT, and SA, and LT/UT and SA/UT muscle activity ratios during maximal shoulder abduction were measured immediately after SR-CCFE. A paired t-test and Wilcoxon signed-rank test were used to determine the significance of differences in scores between pre- and post-intervention in the same group. Results: The CVA (p<.001) and shoulder abduction ROM (p<.001) were increased significantly post-versus pre-intervention. Shoulder pain was decreased significantly (p<.001), and LT (p<.05) and SA (p<.05) muscle activities were increased significantly post- versus pre-intervention. The LT/UT muscle activity ratio was increased significantly post- versus pre-intervention (p<.05). However, there was no significant change in UT muscle activity and SA/UT muscle activity ratio between pre- and post-intervention (p>.05). Conclusion: SR-CCFE was an effective intervention to improve FHP and induce downstream effect from the neck to the trunk and shoulders in subjects with FHP.

• Physical Therapy Korea
• /
• v.16 no.4
• /
• pp.37-43
• /
• 2009

This study compared the electromyographic activities and input performance of computer operators using a computer mouse and a trackball. Muscle activities were assessed at the upper trapezius (UT), middle deltoid (MD), extensor digitorum (ED), and first dorsal interosseous muscle (FDI). Twenty-six healthy subjects were recruited, and the test order was selected randomly for each subject. The task set was to click moving targets on a Windows program. The EMG amplitude was normalized using the percentage of reference voluntary contraction for UT and MD and the percentage of maximal voluntary contraction for ED and FDI. To analyze the differences in EMG activity, a paired t-test was used. UT muscle activities were significantly greater when the computer mouse was used (p<.05). FDI muscle activities were significantly greater when the trackball was used (p<.05). Using a trackball can reduce the load on the UT during computer work and help to prevent and manage work-related musculoskeletal disorders.