• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.30-35
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• 2019

Inertial measurement units (IMUs) are widely used for wearable motion-capturing systems in the fields of biomechanics and robotics. When the IMUs are combined with optical motion sensors (hereafter, OPTs) for their complementary capabilities, it is necessary to align the coordinate system orientations between the IMU and OPT. In this study, we compare the application of two coordinate transformation-based orientation alignment methods between two coordinate systems. The first method (M1) applies angular velocity coordinate transformation, while the other method (M2) applies gyroscopic angle coordinate transformation. In M1 and M2, the angular velocities and angles, respectively, are acquired during random movement for a least-square algorithm to determine the alignment matrix between the two coordinate systems. The performance of each method is evaluated under various conditions according to the type of motion during measurement, number of data points, amount of noise, and the alignment matrix. The results show that M1 is free from drift errors, while drift errors are present in most cases where M2 is applied. Thus, this study indicates that M1 has a far superior performance than M2 for the alignment of IMU and OPT coordinate systems for motion analysis.

• Steel and Composite Structures
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• v.32 no.2
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• pp.225-237
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• 2019

In this research, the dynamic stability and nonlinear vibration behavior of a smart rotating sandwich cylindrical shell is studied. The core of the structure is a functionally graded material (FGM) which is integrated by functionally graded piezoelectric material (FGPM) layers subjected to electric field. The piezoelectric layers at the inner and outer surfaces used as actuator and sensor, respectively. By applying the energy method and Hamilton's principle, the governing equations of sandwich cylindrical shell derived based on first-order shear deformation theory (FSDT). The Galerkin method is used to discriminate the motion equations and the equations are converted to the form of the ordinary differential equations in terms of time. The perturbation method is employed to find the relation between nonlinear frequency and the amplitude of vibration. The main objective of this research is to determine the nonlinear frequencies and nonlinear vibration control by using sensor and actuator layers. The effects of geometrical parameters, power law index of core, sensor and actuator layers, angular velocity and scale transformation parameter on nonlinear frequency-amplitude response diagram and dynamic stability of sandwich cylindrical shell are investigated. The results of this research can be used to design and vibration control of rotating systems in various industries such as aircraft, biomechanics and automobile manufacturing.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.15 no.2
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• pp.33-41
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• 2020

Objectives The purpose of this report was to study the circulation of meridian WiGi, YoungGi, from the viewpoint of manual medicine. Methods First, the Korean Medical approach analyzes documents about the circulation of meridian WiGi, YoungGi, and the biomechanical approach is to analyze documents about kinetic force and kinematic movement. The third inherent energy approach is to analyze documents about craniosacral rhythm and visceral motility. Finally, it is to study the correlation between the circulation of meridian WiGi, YoungGi, and the viewpoint of biomechanics force and movement, the inherent energy of manual medicine. Results Meridian WiGi is fast, powerful, and changeful. It circulates through the head and extremities in the daytime and visceral organs at night. The deviation pelvis and distorted thoracic cage create kinetic force and kinematic movement. Meridian YoungGi is very small and soft energy and circulates meridians and visceral organs permanently. Craniosacral rhythm and visceral motility radiate continuously from cranial and visceral organs to the whole body. Conclusions Circulation of meridian WiGi is closely related to the biomechanical approach. In addition, circulation of meridian YoungGi is closely related to the inherent energy approach.

• The Journal of Advanced Prosthodontics
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• v.14 no.6
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• pp.346-359
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• 2022

PURPOSE. Four and six implant-supported fixed full-arch prostheses with various framework materials were assessed under different loading conditions. MATERIALS AND METHODS. In the edentulous maxilla, the implants were positioned in a configuration of four to six implant modalities. CoCr, Ti, ZrO₂, and PEEK materials were used to produce the prosthetic structure. Using finite element stress analysis, the first molar was subjected to a 200 N axial and 45° oblique force. Stresses were measured on the bone, implants, abutment screw, abutment, and prosthetic screw. The Von Mises, maximum, and minimum principal stress values were calculated and compared. RESULTS. The maximum and minimum principal stresses in bone were determined as CoCr < ZrO₂ < Ti < PEEK. The Von Mises stresses on the implant, implant screw, abutment, and prosthetic screws were determined as CoCr < ZrO₂ < Ti < PEEK. The highest Von Mises stress was 9584.4 Mpa in PEEK material on the prosthetic screw under 4 implant-oblique loading. The highest maximum principal stress value in bone was found to be 120.89 Mpa, for PEEK in 4 implant-oblique loading. CONCLUSION. For four and six implant-supported structures, and depending on the loading condition, the system accumulated different stresses. The distribution of stress was reduced in materials with a high elastic modulus. When choosing materials for implant-supported fixed prostheses, it is essential to consider both the number of implants and the mechanical and physical attributes of the framework material.

• Journal of Veterinary Science
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• v.21 no.5
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• pp.69.1-69.11
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• 2020

Background: An inappropriate Q angle may affect the biomechanics of the canine patellofemoral joint. Objectives: The purpose of this study was to evaluate the effects of changes in quadriceps angle (Q angle) on patellofemoral joint pressure distribution in dogs. Methods: Eight stifles were positioned at 45, 60, 75, 90, 105, and 120° of flexion in vitro, and 30% body weight was applied through the quadriceps. Patellofemoral contact pressure distribution was mapped and quantified using pressure-sensitive film. For the pressure area, mean pressure, peak pressure, medial peak pressure, and lateral peak pressure, differences between groups according to conditions for changing the Q angle were statistically compared. Results: Increases of 10° of the Q angle result in increases in the pressure area (P = 0.04), mean pressure (P = 0.003), peak pressure, and medial peak pressure (P ≤ 0.01). Increasing the Q angle by 20° increases the pressure area (P = 0.021), mean pressure (P ≤ 0.001), peak pressure (P ≤ 0.01), and medial peak pressure (P ≤ 0.01) significantly, and shows higher mean (P ≤ 0.001) and peak pressures than increasing by 10°. Decreasing the Q angle increases the mean pressure (P = 0.013), peak pressure, and lateral peak pressure (P ≤ 0.001). Conclusions: Both increases and decreases in the Q angle were associated with increased peak patellofemoral pressure, which could contribute to the overloading of the cartilage. Therefore, the abnormal Q angle should be corrected to the physiologically normal value during patellar luxation repair and overcorrection should be avoided.

• Clinical Pain
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• v.20 no.1
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• pp.49-52
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• 2021

Bertolotti's syndrome (BS) refers to chronic low back pain (LBP) associated with lumbosacral transitional vertebrae (LSTV). Many studies suggest that the anomalous articulation alters biomechanics, resulting in discomfort on the ipsilateral side. Herein, we present an unusual case of BS presenting pain on the non-articulated side. A 46-year-old man visited our clinic with history of chronic LBP, refractory to treatment of analgesics, modalities and manual therapies. Electrodiagnostic studies showed no evidence of lumbosacral radiculopathy. Radiographies noted unilateral pseudoarticulation of L5~S1 vertebrae, on the contralateral side of his pain. The pain improved dramatically after sacroiliac joint block and facet joint block with iliolumbar ligament infiltration on the non-articulated side. Clinicians should be cautious that the unaffected joint in BS may serve an important role in altered lumbopelvic biomechanism, since it might eventually lead to intractable chronic LBP when overlooked.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.141-146
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• 2021

Background: The purpose of the present study was to determine how long superior screws alone or in combination with posterior placement of metaglene screws protruding and penetrating into the scapular spine in reverse total shoulder arthroplasty affect the strength of the scapular spine in a fresh cadaveric scapular model. Methods: Seven fresh cadaver scapulas were allocated to the control group (short posterior and superior screws) and seven scapulars to the study group (spine base fixation with a four long screws, three with both long superior and long posterior screws). Results: The failure load was lower in the spine fixation group (long screw, 869 N vs. short screw, 1,123 N); however, this difference did not reach statistical significance (p>0.05). All outside-in long superior or superior plus posterior screws failed due to scapular spine base fracture; failures in the short screw group were due to acromion fracture. An additional posterior outside-in screw failed to significantly decrease the failure load of the acromion spine. Conclusions: The present study highlights the significance of preventing a cortical breach or an outside-in configuration when a superior or posterior screw is inserted into the scapular spine base.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.29 no.2
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• pp.39-48
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• 2023

Background: The position of pitcher requires a lot of repetitive motion, and because of this, it is known that not only professional baseball players, but also middle and high school players are frequently exposed to injuries in baseball. The purpose of this study is to examine the differences in upper extremity muscle activity during repeated pitching and the activity of each muscle during repeated pitching by analyzing middle and high school pitchers, divided into groups by age. Methods: Twenty participants (10 middle school male students and 10 high school male students) were recruited for this research. The outcome measures included neuromuscular motor control, including the upper trapezius (UT), triceps brachii (TB), deltoid (DT), latissimus dorsi (LD), biceps brachii (BB), pectoralis major(PM), extensor carpi radialis(ER), and flexor carpi radialis (FR). Results: The two-way analysis of varaince (ANOVA) was used to compare the muscle activity variables between the middle school and high school students. The one-way ANOVA was used to compare the muscle activity variables within time differences each groups. Conclusion: Our results provided promising clinical evidence that guide for upper extremity muscles to increase pitching efficiency in middle and high school base ball players.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.436-445
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• 2022

Objective: Deformation of soft tissues around the neck and scapularcan caused by forward head posture(FHP), which has an uncomfortable effect on biomechanical changes in the scapula as well as functional disorders of the shoulder. However, studies related to direct FHP, biomechanical changes in the scapulafunction, and shoulder pain and disorder have not yet been conducted. Therefore, purpose of this study is to effect of decresedthe FHP on the shoulder function of the sacpular biomechanical examine the change in the shoulder painand disorder. Design: A randomized controlled trial Methods: The participants were 32adults(23.03±3.90 years) recruited and redivided randomly into Forward head posture corrective exercise(FHPCE) vs Control. The FHPCE group was proceeded according to the over load principle through 2steps biofeedback exercise and corrective exercise(n=16). The control (n=16) was TENS did not operated and padding 20 minute. This study was conducted 3 times a week for 4a weeks. Results: FHPCE group is improve in the results of craneocervical angle(p<0.05, 95% CI: 0.352, 4.073). In Mechanical changes of scapula in the shoulder flexion more significant improvement in FHPCE than control group[Axis X(p<0.05), Y(p<0.01), Z(p<0.01)], and shoulder abductionmore significant improvement in FHPCE than control group[xis X(p<0.01)], as well FHPCE showed significant increased in the results in the shoulder pain(p<0.05, 95% CI: -13.244, -1.566) Conclusions: This study suggected that FHP affects the biomechanical changes of the shoulder, and a new method for shoulder pain intervention

• Physical Therapy Rehabilitation Science
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• v.12 no.2
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• pp.130-139
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• 2023

Objective: This study aimed to analyze the effects and characteristics of the height of the treatment table on the force and time of ground reaction (GR) and contact hand (CH) generated from the therapist's feet to generate thrust during spinal manipulation (SM). Design: A cross-sectional survey study Methods: Thirty-six healthy subjects were recruited. SM was performed on the ilium using a knee-high table, where the therapist felt it was easy to control the subject's posture and body shape and comfortable to generate force, as well as a relatively high thigh-high table. The force and time generated by the therapist's GR and CH were simultaneously measured through a force plate. Results: As a result, there was a significant difference in peak force and rundown force at the therapist's GR according to the table height (p < 0.05). In the therapist's CH, there was a significant difference between PreMin (preload minimum) force and peak force (p < 0.05), and there was a significant difference between the time from PreMin to peak and the time of the entire section (p < 0.05). Conclusions: As a result, the generation of increased CH force and faster thrust duration were confirmed by mobilizing the reduced GR force of the therapist to generate thrust than the relatively high table on the knee-high table.