• Geomechanics and Engineering
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• v.8 no.3
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• pp.305-321
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• 2015

In this paper, a new hyperbolic shear deformation plate theory based on neutral surface position is developed for the static analysis of functionally graded plates (FGPs). The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present new hyperbolic shear deformation plate theory and the neutral surface concept, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• Steel and Composite Structures
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• v.15 no.5
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• pp.467-479
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• 2013

In this paper, a new first-order shear deformation beam theory based on neutral surface position is developed for bending and free vibration analysis of functionally graded beams. The proposed theory is based on assumption that the in-plane and transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. The neutral surface position for a functionally graded beam which its material properties vary in the thickness direction is determined. Based on the present new first-order shear deformation beam theory and the neutral surface concept together with Hamilton's principle, the motion equations are derived. To examine accuracy of the present formulation, several comparison studies are investigated. Furthermore, the effects of different parameters of the beam on the bending and free vibration responses of functionally graded beam are discussed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.4
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• pp.447-452
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• 1995

In this paper a simple method of a position control for brushless DC motor is presented. For precise position control, a high performance torque controller is needed and a novel current control method is proposed. The current controller detects the uncommutating mode current for every 60.deg. (elec. angle) and controls it with PI controller. The current control loop includes the feedforward of back EMF and the feedforward of the neutral voltage between the neutral point of the inverter and the neutral point of the machine. In the position control, the acceleration pattern is calculated from the position reference. Then the speed trajectory is calculated from the acceleration pattern. The experimental results are presented to verify the proposed methods.

• Steel and Composite Structures
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• v.20 no.5
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• pp.963-981
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• 2016

A nonlocal trigonometric shear deformation beam theory based on neutral surface position is developed for bending, buckling, and vibration of functionally graded (FG) nanobeams using the nonlocal differential constitutive relations of Eringen. The present model is capable of capturing both small scale effect and transverse shear deformation effects of FG nanobeams, and does not require shear correction factors. The material properties of the FG nanobeam are assumed to vary in the thickness direction. The equations of motion are derived by employing Hamilton's principle, and the physical neutral surface concept. Analytical solutions are presented for a simply supported FG nanobeam, and the obtained results compare well with those predicted by the nonlocal Timoshenko beam theory.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.45-51
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• 2011

Purpose: To determine the correct measurement methods of the ankle joint complex range of motion for measuring the neutral position and evaluate the rater reliability. In addition, the impact of training on the rater reliability was also assessed. Methods: The subjects were eleven healthy women, who were evaluated by two physical therapists and one physical therapist recorded the results of the study. Standard goniometer was used as the measurement tool. The ankle and subtalar joint neutral position and the active range of motion of the ankle and subtalar joint were measured. Intra-rater reliability and inter-rater reliability measures were analyzed with intraclass correlation coefficients. Results: Intra-rater reliability and inter-rater reliability ranged from high to medium for the neutral position of the ankle joint complex. Intra-rater reliability for dorsiflexion and plantarflexion measurements was medium, while the inter-rater reliability was high. The range of motion of the subtalar joint was measured, and the intra-rater reliability and inter-rater reliability were low and medium, respectively Also, the intra-rater reliability was increased with formal training of the measurement techniques. Intra-rater reliability was reduced in case the raters had not undertaken the training. Conclusion: In summary, the results obtained with the measurement tools and joint measurement of position, indicate the consistency of repeated measurements made by the same observers. Under the same circumstances along with repetition of the same measurement technique during training caused an increase in the rater reliability of formally trained raters.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.16 no.2
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• pp.18-27
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• 2010

Purpose: This study is to identify the muscle fatigue and pain by various cervical positions in the VDT work. Methods: Twenty two volunteers (11 males and 11 females) participated in this study. Each subject gazes monitor in front of them for thirty minutes in the three cervical positions (neutral, 30 degree flexed, and 30 degree extended positions). Visual analogue scale (VAS) for the pain and pressure pain threshold(PPT) of the trapezius and levator scapula for the muscle fatigue were measured every fifteen minutes. Results: VASs after 15 minutes were $1.23{\pm}0.43$ in neutral, $3.0{\pm}0.93$ in flexed, and $5.27{\pm}1.03$ in extended position respectively and increased to $1.5{\pm}0.67$, $4.59{\pm}1.26$, and $7.73{\pm}0.98$ after 30 minutes. The order of magnitude of VAS was extended, flexed, and neutral position(p<0.01). PPTs in both sides of upper trapezius and levator scapula muscles were decreased at the three positions after 15 and 30 minutes respectively(p<0.01). There were no statistical differences of PPTs in neutral and flexed positions after 15 and 30 minutes(p<0.01). Extended position showed lowest PPTs in both side of upper trapezius and levator scapula muscles after 15 and 30 minutes(p<0.01). There were statistical differences of PPTs in extended position and the other two positions after 15 and 30 minutes(p<0.01). Conclusion: The cervical position that has the most influence on the cervical muscle fatigue and pain in the VDT work is extended position.

• The Korean Journal of Emergency Medical Services
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• v.14 no.1
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• pp.5-18
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• 2010

Objective : This study compares Video laryngoscope and Direct laryngoscope in tracheal Intubation on rapidity and accuracy by paramedic and aims to improve efficiency of airway management and survival rate in pre-hospital treatment for the patients with severe trauma, cardiac arrest or dyspnea caused by acute diseases. Methods : 60 paramedics were recruited from 13 fire stations located in C province. With the consent of the paramedics, likelihood ratio test was carried out and they were divided into two different groups; DL group (30) and GVL group (30). Regarding intubation conditions, difficult airway grade I, grade II and grade III as well as sniffing position and neutral position were examined. This study also compared between ambulance in motion and in stand still. Frequency, average and standard deviation were analyzed with statistics program, SPSS WIN 17.0 and repeated measure design was introduced to examine inter-relations between position, grade and groups. Results : Intubation was performed more rapidly in neutral position and GVL than in sniffing position and DL(F = 15.260, p = .000). Rapidity value was better with grade I and grade II than grade III and better with GVL than DL(F = 32.629, p = .000). Accuracy value was higher with neutral position and GVL than sniffing position and DL(F = 5.008, p = .011). grade III was less accurate than grade I, grade II and GVL was more accurate than DL(F = 10.966, p = .000). Ambulance motion status did not show any statistically significant differences in accuracy and rapidity. Conclusion : Given this study results, neutral position is better for the patient with severe trauma. For a better survival, GVL intubation can be considered since GVL can enhance accuracy as well as rapidity regarding difficult airway. Since there is no significant differences in ambulance motion factors, intubation can be recommended even in moving ambulance for shortening traveling time to a hospital.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.1
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• pp.1406-1412
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• 2018

This study aimed to measure the grip strength of the dominant and non dominant hands of right-handed normal adults in the supination, pronation, and neutral positions of the forearms. The subjects of this study were instructed to make the standard posture suggested by the American Society of Hand Therapists (ASHT) in order to minimize the impact of changes in the posture of the body as follows. The grips strength was statistically different between groups (p<.05). In the follow up test using Scheffe test, the grips in the neutral position and supinator position did not show any difference, while the grip in the pronation was smaller than those of the above two other positions. The grips of the mainly used forearm and non-mainly used forearm of the study target did not show any statistically significant difference in the neutral, supinator and pronation positions of the forearm. This study is expected to provide basic information for studying the impact of the positions of the forearms on grip strength, assessing the prehensility of patients in clinical settings, and setting therapeutic goals.

• PNF and Movement
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• v.19 no.1
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• pp.1-8
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• 2021

Purpose: The purpose of this study was to determine how the position of tibial rotation affects peak force and hamstring muscle activation during isometric knee flexion in healthy women. Methods: Seventeen healthy women performed maximum isometric knee flexion at 30˚ with three tibial rotation positions (tibial internal rotation, neutral position, and tibial external rotation). Surface electromyographic (EMG) activity was recorded from the medial hamstring (MH) and lateral hamstring (LH) muscles. The strength of the knee flexor was measured with a load-cell-type strength-measurement sensor. Data were analyzed using one-way repeated analysis of variance. Results: The results showed that MH and LH activities and peak force were significantly different among the three tibial rotation conditions (p < 0.01). The post-hoc comparison revealed that the MH EMG activity in tibial neutral and internal rotation positions were significantly greater than tibial external rotation (p < 0.01). The LH activity in tibial external rotation was significantly greater than the tibial neutral position and internal rotation (p < 0.01). The peak force of the knee flexor was also greater in the external tibial rotation position compared with the tibial neutral and internal rotation positions (p < 0.01). Conclusion: Our findings suggest that hamstring muscle activation could be changed by tibial rotation.

• Structural Engineering and Mechanics
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• v.57 no.1
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• pp.127-140
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• 2016

In this paper, a new first shear deformation plate theory based on neutral surface position is developed for the static and the free vibration analysis of functionally graded plates (FGPs). Moreover, the number of unknowns of this theory is the least one comparing with the traditional first-order and the other higher order shear deformation theories. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present shear deformation plate theory and the neutral surface concept, the governing equations are derived from the principle of Hamilton. There is no stretching-bending coupling effect in the neutral surface based formulation. Numerical illustrations concern flexural and dynamic behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.