• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1809-1815
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• 2010

This paper presents an improved method for high-resolution rotor position estimation in the permanent magnet synchronous motor (PMSM) drives with low-resolution Hall-effect sensors. The proposed method adopts a gain-scheduled full-order speed observer. Since the quantized position signal, which is obtained from Hall-effect sensors, is basically used as the input of the observer, the sixth-order harmonics are essentially included in the estimated position. To eliminate the harmonic components, the quantized position is linearized by a linear extrapolation based on the estimated average speed and futhermore the speed-depentent observer gain scheduling strategy is developed. The observer gain is also scheduled by considering the motor acceleration to improve the dynamic performance according to the changes of the motor speed and load. Several experiments are performed for 800W PMSM drive and the results demonstrate the effectiveness of the proposed method.

• Journal of Korean Critical Care Nursing
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• v.11 no.1
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• pp.79-88
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• 2018

Purpose : This study was performed to evaluate the effects of a prolonged a $30^{\circ}$ side-lying position on comfort and skin condition by applying the trunk maintenance repositioning method, which can keep the $30^{\circ}$ side-lying position effective for preventing pressure ulcers. Method : Fifty-four healthy nurses working at a general hospital in Seoul were randomly assigned to an experimental group (n=27) or a control group (n=27) and assumed a position of lying on their right or left side for two hours. The trunk maintenance repositioning method was applied to the experimental group using the pillow made by the researcher, while the original repositioning method was applied to the control group using the regular pillow from the subject hospital. Participants' posture angles, comfort, and skin condition were measured at the time of the intervention, as well as at one and two hours after the intervention. Results : There was no statistically significant difference in position angle, comfort, skin condition change, or sacrum and greater trochanter pressure change between the two groups over time. Conclusion : It is necessary to review the method and frequency of change of position in each hospital. In addition, a proper position changing pillow should be developed in consideration of patients' various body shapes.

• Journal of Ocean Engineering and Technology
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• v.32 no.5
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• pp.333-340
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• 2018

This paper addresses the concept of the representative mean position, which was devised to improve the numerical efficiency of a time domain fatigue analysis of a mooring chain. To investigate the influence of an artificial offset of the floater on the fatigue of the mooring chain, a parametric study was performed on the moored FPSO under various combinations of offsets and environmental conditions. Tension time histories were calculated using the de-coupled analysis method, and fatigue damages were calculated to determine the influence of the offset. The parametric study was extended to a more realistic case to determine the actual effect of the representative mean position, where a comparison was made between the two different analysis results, one using the representative mean position and the other one using the actual mean position. It was confirmed that the application of the representative mean position guaranteed the conservatism of the fatigue damage with the enhanced numerical efficiency in the time domain fatigue analysis.

• The Journal of Korean Physical Therapy
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• v.28 no.1
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• pp.33-38
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• 2016

Purpose: The aim of this study was to determine the effectiveness of pelvic tilt training using an inclinometer on joint position sense and postural alignment in individuals with stroke. Methods: Thirty-one subjects with chronic stroke were divided into two groups: the experimental group (16 subjects) and the control group (15 subjects). Subjects in both groups received neuro-developmental therapy five times per week. In addition, the patients in the experimental group also received pelvic tilt training using an inclinometer for 30 minutes, 3 times a week for 4 weeks. Maximal range of anterior, posterior pelvic tilt and joint position sense were used to evaluate pelvic tilt motion. Image analysis was performed for evaluation of postural alignment on in standing position. Results: Significant difference in Iimprovement of pre- and post-intervention of joint position sense was observed showed significant difference (p<0.05) in all groups. Experimental groups showed sSignificant differences in maximal range of posterior pelvic tilt in on the paretic side were observed in the experimental groups compared to with the control group (p<0.05). Conclusion: These findings suggest that pelvic tilt training using an inclinometer may help to improve range of pelvic tilt and joint position sense of stroke patients.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1154-1159
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• 2018

Precise prediction of the radiation interaction position in scintillators plays an important role in medical and industrial imaging systems. In this research, the incident position of the gamma rays was predicted precisely in a plastic rod scintillator by using attenuation technique and multilayer perceptron (MLP) neural network, for the first time. Also, this procedure was performed using nonlinear regression (NLR) method. The experimental setup is comprised of a plastic rod scintillator (BC400) coupled with two PMTs at two sides, a $^{60}Co$ gamma source and two counters that record count rates. Using two proposed techniques (ANN and NLR), the radiation interaction position was predicted in a plastic rod scintillator with a mean relative error percentage less than 4.6% and 14.6%, respectively. The mean absolute error was measured less than 2.5 and 5.5. The correlation coefficient was calculated 0.998 and 0.984, respectively. Also, the ANN technique was confirmed by leave-one-out (LOO) method with 1% error. These results presented the superiority of the ANN method in comparison with NLR and the other methods. The technique and set up used are simpler and faster than other the previous position sensitive detectors. Thus, the time, cost and shielding and electronics requirements are minimized and optimized.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.38-48
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• 2011

Purpose: Dentists suffer back, neck and shoulder pain during their careers due to bad operating posture. If dentists have a good operating posture ergonomically, there would be less pain and discomfort in the shoulder and back. Therefore, dentists should learn the Home position which enables dentists to approach a stable posture ergonomically. This study was to compare tooth preparation in the Home position and the Random position, and evaluate the clinical efficacy of the Home position. Materials and methods: Tooth preparation for fixed partial denture was performed on the maxillary left 2nd premolar and maxillary left 2nd molar at the two different operating positions were compared. The amount of occlusal reduction, marginal width, subgingival margin depth, and convergence angle were measured. A T-test was performed separately to compare the results of the Random position and the Home position. Results: 1. The amounts of average thickness of occlusal reduction on fossa were deficient to the ordered ones in the Random position and the Home position (P > .05). 2. The average subgingival margin depth of prepared margin on maxillary left 2nd premolar, maxillary left 2nd molar were excessive in the Random position than in the Home position. On the maxillary left 2nd premolar, there was no statistical difference in the Random position and the Home position except Distal midline, DL line angle, Lingual midline, ML line angle (P< .05). On the maxillary left 2nd molar, there was no statistical difference in the Random position and the Home position (P < .05). 3. Average convergence angle in the Random position and the Home position were excessive compared to the ordered angle. There was no statistical difference in the Random position and the Home position (P > .05). 4. Analysis of pearson correlation : In the Random position, the amounts of average thickness of occlusal reduction, the average subgingival margin depth of prepared margin, convergence angle were significantly associated with each other (P < .05). But in the Home position, they were not significantly associated with each other (P < .05). 5. The time needed for preparation in the Home position was faster or equal than that of the Random position as time went on. Conclusion: In conclusion, there were no significant differences between Home position and Random position in measures of occlusal reduction, marginal width, marginal depth, convergence angle. However, preparation time and incidence of damaging adjacent teeth were less in Home position than in Random position. Therefore, if trained properly, Home position which is more ergonomically stable can be adopted for clinical use.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1540-1551
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• 2015

The detection of position and speed in BLDC motors without using position sensors has meant many efforts for the last decades. The aim of this paper is to develop a sensorless technique for detecting the position and speed of BLDC motors, and to overcome the drawbacks of position sensor-based methods by improving the performance of traditional approaches oriented to motor phase voltage sensing. The position and speed information is obtained by computing the derivative of the terminal phase voltages regarding to a virtual neutral point. For starting-up the motor and implementing the algorithms of the detection technique, a FPGA board with a real-time processor is used. Also, a versatile hardware has been developed for driving BLDC motors through pulse width modulation (PWM) signals. Delta and wye winding motors have been considered for evaluating the performance of the designed hardware and software, and tests with and without load are performed. Experimental results for validating the detection technique were attained in the range 5-1500 rpm and 5-150 rpm under no-load and full-load conditions, respectively. Specifically, speed and position square errors lower than 3 rpm and between 10º-30º were obtained without load. In addition, the speed and position errors after full-load tests were around 1 rpm and between 10º-15º, respectively. These results provide the evidence that the developed technique allows to detect the position and speed of BLDC motors with low accuracy errors at starting-up and over a wide speed range, and reduce the influence of noise in position sensing, which suggest that it can be satisfactorily used as a reliable alternative to position sensors in precision applications.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.3
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• pp.59-66
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• 2017

PURPOSE: This study was to evaluate the muscle activity of gluteus medius, tensor fascia latae, and quadratus lumborum during side-lying abduction exercise in various pelvic tilting positions. METHODS: We measured the activity of three muscles in three pelvic tilt positions for 17 normal subjects with performing the side-lying hip abduction. Three pelvic tilt positions were posterior tilt, neutral tilt and anterior tilt. We used the mean value after participants performed the hip abduction three times each position. RESULTS: The activity of gluteus medius within three pelvic positions showed the highest activity in pelvic posterior tilt position and the lowest in pelvic neutral tilt position (p = .04). The activity of tensor fascia latae showed the lowest in pelvic posterior tilt position and the highest in pelvic posterior tilt position (p = .00). The activity of quadratus lumborum revealed the lowest activity in pelvic neutral tilt position and the highest in pelvic anterior tilt position (p = .00). The activity of selective gluteus medius activation according to pelvic displacement showed the highest activity in pelvic neutral tilt position and lowest in pelvic anterior tilt position (p = .00). CONCLUSION: Hip abduction with Pelvic posterior tilt position may be effective in increasing gluteus medius and may be effective in strengthening exercise program for the gluteus medius. In addition, Hip abduction with pelvic neutral position may have an effect on the selective gluteus medius, which is considered to be effective in the exercise program for muscle reeducation training of the gluteus medius.

• Journal of the Ergonomics Society of Korea
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• v.6 no.2
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• pp.19-28
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• 1987

If an error occurs in the automatic mode when the advanced teleoperator system performs a task in hostile environment, then the mode changes into the manual mode. The operation by program and the operation by hyman recover the error in the manual mode. The system resumew the automatic mode and continues the given task. In order to utilize the inverse kinematics as means of the operation by program in the manual mode, Lee and Nagamachi determined the end point of the robot trajectory planning which varied with the height of the task object recognized by a T.V monitor, solved the end point by the fuzzy set theory, and controlled the position of the robot hand by the inverse kinematics and the posture of the robot hand by the operation by human. But the operation by human did take a lot of task time because the position and the posture of the robot hand were separately controlled. To reduce the task time by human, this paper developes an error recovery expert system (ERES). The position of the robot hand is controlled by the inverse kinematics of the cartesian coordinate system to the end point which is deter- mined by the fuzzy set theory. The posture of the robot hand is controlled by the modulality of the robot hand's motion which is made by the posture of the task object. The knowledge base and the inference engine of the ERES is developed using the muLISP-86 language. The experimental results show that the average task time by human the ERES which was performed by the integration of the position and the posture control of the robot hand is shorter than that of the research, done by the preliminary experiment, which was performed by the separation of the position and the posture control of the robot hand. A further study is likely to research into an even more intelligent robot system control usint a superimposed display and digitizer which can present two-dimensional coordinate of the work space for the convenience of human interaction.

• Imaging Science in Dentistry
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• v.43 no.2
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• pp.71-75
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• 2013

Purpose: This study was performed to determine the position of the mental foramen relative to the apices of the teeth based on panoramic radiographs in a Moroccan population. We also analyzed gender differences and the symmetry of location within individuals. Materials and Methods: Seven hundred ninety-four panoramic radiographs were evaluated with regard to the location and symmetry of the mental foramina in male and female subjects. The results were analyzed using Pearson's ${\chi}^2$ and Fisher's exact test. Results: Of the 794 panoramic radiographs, 377 met the inclusion criteria for at least one side. The mental foramen was located just below the apex of the second premolar in 62.7% of the patients and between the first and second premolars in 30%. It was symmetrically located in 79%. No statistically significant differences were found between males and females in the position and symmetry of the mental foramen. Conclusion: The most common position for the mental foramen in this sample was in line with the second premolar.