• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.92-94
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• 2005

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studios have been performed for the elimination of speed and position sensors. This paper investigates a novel speed sensorless control of a permanent magnet synchronous motor. The proposed control strategy compensates a speed error through the difference between the calculated and measured reactive power. The proposed algorithm is verified through the simulation and experimentation.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.182-185
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• 1998

This paper describes a field orientation control of an induction motor without any speed transducer and proposes a wide-range speed control strategy with the field orientation algorithm. The difference at impedances between the direct and quadrature axis at the injected signal is used for the sensorless field orientation control. But this algorithm has some limitations and should be supported by other method at high speed. In this paper, a sensorless speed control at an induction motor for wide speed range operation is proposed. The proposed algorithm is verified by experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.337-339
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• 2020

Speed-run is a gameplay style in what the player tries to finish the game as quickly as possible. The purpose of this study is to observe and analyze the difference between a normal player and a speed runner in a speed run to better understand their interaction with the game and to extrapolate the applications of the analyzed frameworks to scenarios that extent normal gameplay. For this purpose, MDA (Mechanic, Dynamic, Aesthetics) and DPE (Experience, Design, Play) were used. As a result, the average player was found to focus on aesthetics or affects while the speed runner focused on mechanics and gameplay.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2376-2384
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• 2018

To reduce the size and cost of motor driving systems, several methods for driving multiple parallel-connected motors with a single inverter have been proposed. However, dual PMSMs driven by a single inverter, unlike induction motors, have a problem with instability due to system resonance caused by disturbances such as load imbalance and tolerances between two motors. To drive dual SPMSMs fed by a single inverter, this paper proposes an active damping algorithm to effectively suppress resonance by using one-sided sensorless speed control and position difference estimation. By deriving rotor position difference from d-q current differences between two motors, the proposed method is affected less by position difference estimation errors and is simpler than dual sensorless position estimation.

• The Journal of Korean Medicine
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• v.34 no.1
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• pp.80-88
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• 2013

Objectives: The purpose of this study was to examine the effect of Temporomandibular joint Balance Appliance for Golf (TBA-G) of Functional Cerebrospinal Therapy (FCST) on golf driver head speed and back muscle power. Methods: Twenty-one participants that had a golf career of 4 years or more were involved. We measured golf drive head speed and back muscular strength before and after applying TBA-G in the mouth. A paired t test or Wilcoxon singed rank test was performed to identify the difference of effect between before and after applying TBA-G, using IBM SPSS 19.0. We considered difference significant at P<0.05. Results: Driver head speed increased significantly by 2 mph (1.99%) after applying TBA-G [from $100.52{\pm}9.82$ mph ($mean{\pm}SD$) to $102.52{\pm}10.43$ mph, P<0.001]. Back muscular strength also increased by 7.28 kg (5.60%) [from $129.90{\pm}28.31$ kg to $137.18{\pm}28.81$ kg, P<0.001]. In stratification analysis, a more significant increase was found in the drive head speed and back muscular strength of groups of males with weight more than 69kg, with height more than 175cm, and with golf experience more than 7 years, compared to those of other groups. Conclusions: The results suggest that TBA-G could improve golf drive head speed and back muscular strength.

• Physical Therapy Korea
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• v.9 no.1
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• pp.43-51
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• 2002

Physiological Cost Index (PCI) of walking has been widely used to predict oxygen consumption in healthy subjects or patients. The purpose of this study was to evaluate the predictability of physiological cost index of walking for the amount of exercise and cardiac function. Walking exercise was conducted in 67 healthy children (age 4-12) with a self-selected comfortable walking speed on the level surface. Walking speed was calculated, and heart rate was measured before and immediately after the walking. PCI was calculated for statistical analysis. The results were as follows; 1) The walking speed tends to increase and PCI of walking tends to decrease with age. There was significant difference in walking speed and PCI of walking among three age groups (p<.05). The change of walking heart rate tends to decrease with age, however, there was no significant difference among three age groups. 2) Linear regression equation between walking speed and age was 'Y (walking speed) = 2.124X (age) + 48.286' ($R^2$=.337), (p=.00). 3) The walking heart rate tends to decrease with age. Linear regression equation between walking heart rate and age was 'Y (walking heart rate) = 143.346 - 2.63X (age)' ($R^2$=.3425), (p=.00). 4) The walking heart rate decreased as body surface area (BSA) increased. Linear regression equation between walking heart rate and BSA was 'Y (walking heart rate) = 149.830 - 27.115X (BSA)' ($R^2$=.3066), (p=.00). In conclusion, these equations and PCI could be useful to quantify the variation of energy expenditure of children with pathological gait when compared with age-matched healthy children.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.3
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• pp.143-151
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• 2020

Purpose: This study aimed to investigate the effect of single-leg stance training according to different support surfaces on walking speed and balance in patients with chronic hemiplegia. Methods: Twenty-two patients with chronic stroke were randomly categorized into an experimental group (11 patients) and a control group (11 patients). In the experimental group, single-leg stance training was performed on an unstable surface after 50 min of general physical therapy. In the control group, single-leg stance training was performed on a stable surface after 50 min of general physical therapy. All participants performed five sets of single-leg stance exercises per minute and rested for 3 min. The intervention was performed 5 times a week for 4 weeks, and each patient was evaluated using the Berg Balance Scale (BBS), Fugl-Meyer Assessment Scale (FMA), and difference in walking speed between the first and last day of the intervention. Results: Compared to baseline measurements, both study groups showed significant increases in FMA, BBS, and walking speed (p<.05) after the intervention. However, there was no statistically significant difference (p>.05) between the experimental and control groups. However, in the experimental group, the increases in FMA, BBS, and walking speed were 3.36 %, 9.50 %, and 7.71 %, respectively. In the control group, the increases in FMA, BBS, and walking speed were 2.39 %, 6.65 %, and 7.64 %. Conclusion: Single-leg stance training on different support surfaces could help improve walking ability and balance in patients with chronic hemiplegia.

• PNF and Movement
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• v.13 no.2
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• pp.73-80
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• 2015

Purpose: The purpose of this study was to determine the effect of symmetrical-reciprocal pattern of scapula and pelvis exercises using proprioceptive neuromuscular facilitation (PNF) on gait speed and balance in patients with hemiplegia. Methods: Among the adult patients with hemiplegia that were hospitalized at Michuhol Rehabilitation Center after being diagnosed with stroke, 10 that were capable of independent walking for more than five minutes and that understood and cooperated with the therapy and test methods of this research, were selected as subjects. The therapy was implemented based on the concept of PNF, and it was performed on a low mat and a height-adjustable mat, as proscribed by the fundamental procedure for PNF. Symmetrical-reciprocal pattern of scapula and pelvis exercises were applied to the patients in the decubitus position. The therapy scheme included stabilizing reversals, rhythmic stabilization, and a combination of isotonics, rhythmic initiation, and dynamic reversals. To investigate gait speed and body trunk mobility before and after the symmetrical-reciprocal pattern of scapula and pelvis exercises were applied, walking speed for a distance of 10 m was measured and balance was tested based on the Berg-Balance scale test table. The Berg-Balance scale test was performed by one therapist to minimize any error that could occur from the subjective evaluation method used by therapists. Results: Gait speed increased by 8.97 seconds after applying the symmetrical-reciprocal pattern of scapula and pelvis exercises using the concept of PNF, showing a significant difference (p<0.01). However, balance showed no significant difference after the therapy (p>0.14). Conclusion: Exercise therapy that uses the symmetrical-reciprocal pattern of scapula and pelvis with the concept of PNF can be said to be a useful therapeutic technique that can enhance the walking speed of patients with hemiplegia.

• 재활복지
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• v.22 no.2
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• pp.231-246
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• 2018

Diadochokinesis (DDK) aims to identify the evaluating the oral mitor ability and the moter coordination ability. There are few DDK normative data on elementary school students in Korea, The purpose of this study was to investigate the characteristics of the speed and regularity of DDK in first- and second-grade students in elementary school. The subjects were a total of 194 students in first- (45 males, 50 females) and second-grade (47 males, 52 females) in elementary schools in Gwangju Metropolitan City. As evaluation tasks, AMR task 'p?', 't?', and 'k?' and SMR task 'p?t?k?' were performed. The speed and regularity of DDK was measured using Motor speech profile (Model 5141, KayPENTAX) and Praat (v6.0.3.6). The results of this study, First, there was a statistically significant difference by grade in AMR speed for 'p?', 't?', and 'k?' and the AMR speed was faster in second grade group. And, there was no statistically significant. Second, AMR regularity showed a statistically significant difference in 'p?', 't?', and 'k?' according to sex and was found to be more regular in female student group. There was no significant difference in regularity by grade. Third, the SMR speed showed statistically significant difference in 'p?t?k?' by grade and was faster in second grade group. And there was no statistically significant difference by sex. The results of this study showed that the DDK performance ability in first- and second-grade students in elementary school was slightly different according to grade and sex. In future research, it is necessary to investigate the correlation between the articulation accuracy and linguistic intelligibility, and to find out the usefulness of DDK in articulation evaluation.

• Progress in Medical Physics
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• v.18 no.3
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• pp.172-178
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• 2007

An ultrasonic bone densitometer has been developed by measuring speed of sound signal transmitted and received on the skin, not through the horizontal axis but through the vertical one in tissue. The SOS(speed of sound) method measuring the time difference between the ultrasound signals reflected from the both sides of surface of bone could produce more precise result compared with the BUA(broadband ultrasound attenuation) method measuring the frequency difference. Middle finger is selected to be the best measurement position in order to increase the accuracy, after due consideration that the thickness of flesh at the down part of thumb shows too much variation although the ratio of the receiving signal is higher than the other fingers. The measured value by using SOS method shows almost the same result as compared with the conventional DEXA method.