• Smart Structures and Systems
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• v.15 no.2
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• pp.489-503
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• 2015

Response estimation at unmeasured locations using the limited number of measurements is an attractive topic in the field of structural health monitoring (SHM). Because of increasing complexity and size of civil engineering structures, measuring all structural responses from the entire body is intractable for the SHM purpose; the response estimation can be an effective and practical alternative. This paper investigates a response estimation technique based on the Kalman state estimator to combine multi-sensor data under non-zero mean input excitations. The Kalman state estimator, constructed based on the finite element (FE) model of a structure, can efficiently fuse different types of data of acceleration, strain, and tilt responses, minimizing the intrinsic measurement noise. This study focuses on the effects of (a) FE model error and (b) combinations of multi-sensor data on the estimation accuracy in the case of non-zero mean input excitations. The FE model error is purposefully introduced for more realistic performance evaluation of the response estimation using the Kalman state estimator. In addition, four types of measurement combinations are explored in the response estimation: strain only, acceleration only, acceleration and strain, and acceleration and tilt. The performance of the response estimation approach is verified by numerical and experimental tests on a simply-supported beam, showing that it can successfully estimate strain responses at unmeasured locations with the highest performance in the combination of acceleration and tilt.

• Physical Therapy Korea
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• v.10 no.2
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• pp.11-22
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• 2003

The purpose of this study was to analyze the effects of three different pelvic tilts on a sit-to-stand (STS) and to suggest a new assessment approach based on biomechanical analysis. The three difrent pelvic tilts were: (1) comfortable pelvic tilt sit-to-stand (CPT STS), (2) posterior pelvic tilt sit-to-stand (PPT STS) and (3) anterior pelvic tilt sit-to-stand (APT STS). To determine the onset time of muscle contraction surface electrodes were applied to the rectus femoris muscle (RF), vastus lateralis muscle (VL), biceps femoris muscle (BF), tibialis anterior muscle (TA), gastrocnemius muscle (GCM), and soleus muscle (SOL). The ICC was used for functional linkage analysis. The findings of this study were as follows. First, significant differences were found in kinematic variables and in muscle activation pattern among the three activities. Second, the results of functional integrated analysis revealed that recruited muscle activation patterns changed when the thigh-off was viewed as a reference point. Third, there were independent functional units between the thigh-off and the VL and between the thigh-off and the RF in the functional linkage analysis. The VL and RF acted as prime mover muscles, and more postural adjustment muscle recruitment was required as the demand of postural muscle control increased (PPT STS, APT STS, and CPT STS in order). In conclusion, the findings of this study suggest the following evaluative and therapeutic approach for STS activity. APT STS can be introduced for movement efficiency and functional advantage when abnormal STS is treated. However, excessive APT would change the muscle activation patterns of BF and SOL and require additional postural muscle control to cause abnormal control patterns.

• Physical Therapy Korea
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• v.26 no.4
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• pp.10-19
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• 2019

Background: In patients with lumbar spinal stenosis (LSS), lumbar flexion exercise (LFE) is considered a standard therapeutic exercise that widens the space between the spinal canal and intervertebral foramen. However, some researchers have reported that lumbar extension exercise (LEE) may improve lumbar pain and functional ability in patients with LSS. Although exercise intervention methods for patients with LSS have been widely applied in clinical settings, few studies have conducted comparative analysis of these exercise methods. Objects: This study aimed to compare the effects of LFE, LEE, and lumbar flexion combined with lumbar flexion-extension exercise (LFEE) on pain, range of motion (ROM), pelvic tilt angle, and functional gait ability in patients with LSS. Methods: A total of 30 patients with LSS, LFE (n1=10), LEE (n2=10), and LFEE (n3=10) were assigned to each of the three exercise groups. The numerical pain rating scale (NPRS), modified-modified schober test (MMST)-flexion, MMST-extension, pelvic tilt inclinometer, and 6-minute walking test (6MWT) were measured. Results: After the intervention, statistically significant differences were observed in the NPRS (p=.043), MMST-flexion (p<.001), MMST-extension (p<.001), and 6MWT (p=.005) between groups. According to the post hoc test, the NPRS was statistically significant difference between the LFEE and LEE groups (p=.034). The MMST-flexion was statistically significantly different between the LFE and LEE (p=.000), LFE and LFEE (p=.001), and LEE and LFEE (p=.001) groups. The MMST-extension was statistically significantly different between the LFE and LEE (p<.001), LFE and LFEE (p=.002), and LEE and LFEE (p=.008) groups. The 6MWT was statistically significantly different between the LFE and LFEE (p=.042) and the LEE and LFEE (p=.004) groups. Conclusion: This study suggested that LFEE was the most effective exercise for pain and functional gait ability in patients with LSS, LFE was the most effective exercise for lumbar flexion ROM, and LEE was the most effective exercise for lumbar extension ROM.

• Physical Therapy Rehabilitation Science
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• v.12 no.3
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• pp.214-221
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• 2023

Objective: This study aimed to assess the impact of using the LED light electromyographyfeedback system (EMG-light) during Pilates exercises in women to maintain consistent muscle contraction in the abdominal external oblique muscles and reduce muscle contraction in the upper trapezius muscles. This study compared Pilates training using the EMG-light with Pilates training only in healthy women for 4 weeks. Design: This study was conducted as a cross-sectional study. Methods: A total of 17 healthy women were divided into an experimental group (n=9) and a control group (n=8). Both groups performed Pilates exercises as assigned, twice per week for four weeks, with each session lasting fifty minutes. The experimental group were used the EMG-light feedback system during pilates exercise while the control group did not use EMG-light. We used cervical vertebral angle (CVA), shoulder tilt angle to evaluate neck posture and standing balance with closed eye for 30s before and after exercise. Results: The control group exhibited a significant change in CVA (p<0.05). Both groups showed significant changes in shoulder tilt, center of pressure (COP) path-length, and COP velocity during eyes-closed conditions (p<0.05). However, there were significant differences between the experimental and control groups in terms of CVA, shoulder tilt, COP path-length, and COP velocity. Conclusions: This study demonstrated that Pilates exercises had positive effects on shoulder posture and balance. The use of EMG-light provided real-time visual feedback on muscle contraction during Pilates exercise. However, the experimental group did not show significant improvements compared to the control group, which performed Pilates exercises without feedback.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.1
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• pp.49-61
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• 2021

PURPOSE: Hamstring muscle shortening is related to low back pain, and it is important to check the hamstring muscle flexibility and pelvic mobility to analyze the effects of the intervention. This study examined the effects of hamstring muscle shortening on flexibility and pelvic mobility according to the method of stretching the hamstring muscle in patients with low back pain. METHODS: Forty Low Back Pain Patients participated. The subjects performed the Visual Analogue Scale (VAS), Fear Avoidance Belief Questionnaire (FABQ), Korean version of Oswestry Disability Index (KODI), Myovision, and sensbalance therapy cushion (pelvic mobility, proprioception). The subjects were divided into two groups to perform the passive and active stretching protocol. The intervention was conducted three times a week for four weeks. RESULTS: Hamstring muscle flexibility was increased significantly in both groups (p < .05), and there was no difference between the groups. VAS, FABQ was decreased significantly in both groups (p < .01), and there was no difference between the groups. The left lower back muscle impedance was decreased significantly in both groups (p < .05). The passive stretching group showed a significant increase in the pelvic anterior, posterior, and left tilt ROM (p < .05). The active stretching group showed a significant increase in the pelvic anterior, posterior tilt ROM (p < .05). CONCLUSION: Both stretching methods may be useful intervention methods for pelvic mobility and pain recovery and can assess back pain recovery.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.341-349
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• 2001

Numerical calculation has been performed to investigate the fluid flow, heat transfer and local mass fraction of chemical species in the MOCVD(metalorganic chemical vapor deposition) manufacturing process. The mixing of reactants (trimethylgallium with hydrogen gas and ammonia) was presented by the concentration of each reactant to predict the uniformity of film growth. Effects of inlet size, location, mass flow rate and susceptor/cold wall tilt angle on the concentration were reported. From the numerical calculation, the concentration of reactants could be qualitatively predicted by the Nusselt number(heat transfer) and the optimum mass flow rate, wall tilt angle and inlet condition were considered.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.301-309
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• 2019

Purpose : The purpose of this study was to provide an effective method of exercise therapy for patients with cervicogenic headache. Methods : The subjects were divided into the following two groups according to the intervention received: cervical stretch exercise (n=15, control group) cervix-stabilizing exercise (n=15, experimental group) tone (Hz) and stiffness (N/m) of the suboccipital and upper trapezius muscles were measured. T1 slope angle and neck tilt angle were measured. After the exercise program intervention, a greater amount of change in muscle tone and stiffness of suboccipital and upper trapezius muscles was found in the experimental group, as compared to the control group. Greater amount of change in posture was found in the experimental group, as compared to the control group (p<0.05). Results : After the exercise program intervention, a greater amount of change in muscle tone and stiffness of suboccipital and upper trapezius muscles was found in the experimental group, as compared to the control group. Greater amount of change in posture was found in the experimental group, as compared to the control group (p<0.05). Conclusion : The neck-stabilizing exercise were shown to be effective in decreasing the tone of the cervical muscles by stabilizing the cervical bone and improving muscle activity, and in improving the posture by decreasing muscle tone and stiffness.

• The Journal of Korean Physical Therapy
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• v.18 no.5
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• pp.1-11
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• 2006

Purpose: This study was to evaluate effects of myofascial release therapy for newborns and infants with congenital torticollis. Methods: In a two month period, thirty-six newborns and infants diagnosed with congenital muscular torticollis received treatment thirty times; then divided into a myofascial release group and stretching group. Crying frequency was used to measure the amount of crying time during treatment. Ultrasonography was used to measure the size of fibromatosis. Physical examinations were used to measure the degree of head tilting and rotation. Results: The results were as follows: 1. Crying frequency was significantly decreased in myofascial degree group. 2. The size of fibromatosis was not significantly decreased in ultrasonography. 3. Head tilt was significantly decreased in myofascial release group. 4. Rotation was not significantly increased in myofascial release and control group. Conclusion: The above results suggest that myofascial release therapy is helpful decreasing head tilt, crying frequency, and increasing head rotation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.916-922
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• 2001

A mechanical face seal is a tribo-element intended to control leakage of working fluid at the interface between a rotating shaft and its housing. Leakage of working fluid decreases drastically as the clearance of the mating seal faces gets smaller. But the very small seal clearance results in an increased reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals a compromise between low leakage and acceptable seal life is important, and it presents a difficult and practical design problem. A fluid film or sealing dam geometry of the seal clearance affects seal lubrication performance very much, and thereby it is one of the main design considerations. In this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed, using the Galerkin finite element method, which is readily applied to various seal geometries. Film pressures of the sealing dam are analyzed, including the effects of the seal face coning and tilt. Then, lubrication performances of the seals, such as opening forces, restoring moments, leakage, and dynamic coefficients, are calculated, and they are compared to the results obtained by the narrow seal approximation.

• Journal of Drive and Control
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• v.11 no.3
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• pp.31-40
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• 2014

This paper proposes a multi absorbing wave energy converter design, in which a hydrostatic transmission is used to transfer wave energy to electric energy. The most important feature of this system is its combination of the pressure coupling principle with the use of a hydraulic accumulator to eliminate the effects of wave power fluctuation; this maintains a constant speed of the hydraulic motor. Tilt motion of a floating buoy was employed as the power take-off mechanism. Furthermore, a PID controller was designed to carry out the speed control of the hydraulic motor. The design offers some advantages such as extending the life of the hydraulic components, increasing the amount of energy harvested, and stabilizing the output speed.