• Physical Therapy Korea
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• v.9 no.3
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• pp.39-46
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• 2002

In this study, vertical acceleration of center of mass was observed along normal gait phases in 9 healthy male volunteers (aged $25.7{\pm}2.18$). The developed wireless accelerometric device was attached on the intervertebral space between L3 and L4 using a semi-elastic waist belt. A three-dimensional motion analysis system, synchronized with the accelerometry, was used for detecting gait phases. There was no significant correlation between the body weight and the acceleration. The first peak curve covered loading response phase. The second downward peak point was matched accurately with the opposite toe-off. In mid-stance and terminal stance, the acceleration curve highly resembled the vertical ground reaction force curve. There was no significant difference in timing between the final upward peak point and the initial contact. Therefore, the developed accelerometry system would be helpful in determining determine temporal gait pattems in patients with gait disorders.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.940-944
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• 2014

In this research, we designed representative motion patterns that possibly occurred in sleep situation and evaluated the feasibility of the smartphone based movement recording technique. For this, we designed 7 motions such as posture change, head movement, arm movement (vertical, horizontal), leg movement and hand movement (flipping, folding). Movement was recorded by using the smartphone and the actimetry device simultaneously for comparing the feasibility of smartphone based recording. As a result of experiment, we found that the smartphone based movement recording well reflects the body movement, however, it shows the limitation in recording the small local movement such as hand motion compared with the reference actimetry device, Actiwatch.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1634-1640
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• 2017

The study aims to distinguish hemiplegic gait and normal gait using simple wearable device and classification algorithm. Thus, we developed a wearable system equipped three axis accelerometer and three axis gyroscope. The developed wearable system was verified by clinical experiment. In experiment, twenty one normal subjects and twenty one patients undergoing stroke treatment were participated. Based on the measured inertial signal, a random forest algorithm was used to classify hemiplegic gait. Four-fold cross validation was applied to ensure the reliability of the results. To select optimal attributes, we applied the forward search algorithm with 10 times of repetition, then selected five most frequently attributes were chosen as a final attribute. The results of this study showed that 95.2% of accuracy in hemiplegic gait and normal gait classification and 77.4% of accuracy in hemiplegic-side and normal gait classification.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.260-266
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• 2021

Handwriting using the dominant and nondominant arms was analyzed in 52 young adults with the aid of a three-axial accelerometer. We measured a signal vector magnitude (SVM) and the percentage of the total signal vector magnitude (%TSVM) for the metacarpophalangeal joint (MCP), radial styloid process (RSP), and lateral epicondyle (LE) of both arms. The SVM for the MCP was lower in the dominant arm than the nondominant arm, whereas that for the RSP was higher. %TVSM was lower for the MCP than for the RSP and LE in the nondominant arm, but higher for the MCP than for the LE in the nondominant arm. These findings suggest that controlling the MCP will improve the quality of handwriting, including when using the nondominant arm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1066-1069
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• 2002

Dynamic postural control varies with the environmental context, specific task and intentions of the subject. In this paper, dynamic postural control against forward-backward perturbations of a platform was estimated using tri-axial accelerometers and a force plate. Ten young healthy volunteers stood upright in comfortable condition on the perturbation system which was controlled by an AC servo motor. With anterior-posterior perturbations, movements of ankle, knee and hip Joints were obtained by tri-axial accelerometers. and ground reaction forces with corresponding displacements of the center of pressure(CoP) by the force plate. The result showed that the ankle moved first and the trunk forward, which implies that the mechanism of the dynamic postural control in forward-backward perturbations, occurred in the procedure of the ankle, the knee and the hip. Knee flexion and hip extension in the period of acceleration, constant velocity and deceleration phase is very important fur the balance recovery. These responses depends on the magnitude and timing of the perturbation. From the present study the accelerometry-system appears to be a promising tool for understanding kinematic accelerative In response to a transient platform perturbation. A more through understanding of balance recovery mechanism may aid in designing methods for reducing falls and the resulting injuries.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.10
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• pp.452-457
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• 2006

In this paper, an algorithm to detect steps in hemiplegic patients using a 3-axis accelerometer a紅ached on the trunk was proposed. The proposed algorithm consisted of the signal pre-processing, the step detector, the classification of steps and the calculation of stride time. Two FIR band-pass filters were designed and steps were measured by the combination of filtered signals in the vertical and the anteroposterior directions. In addition, the classification of steps and the calculation of stride time were computed by using the detected steps and lateral signals. For the experiment, fourteen hemiplegic patients were participated and the linear accelerations of the trunk and foot switch signals were measured synchronously. To evaluate the system performance, the detected steps and initial contacts by the foot switch were compared. The average error between the steps and initial contacts was 0.024ms and the difference of the average stride time was 0.01s. Finally, all gait events were detected exactly. Results showed that the accelerometry could use for the gait evaluation in clinical rehabilitation therapies.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.289-293
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• 2004

In the present study, knee varus torque and mediolateral accelerations were measured using the three-dimensional motion analysis system and a linear accelerometry in odor to determine the effect of heel wedges during walking. Wedges were inclined with 10$^{\circ}$ and 15$^{\circ}$ in medial and lateral directions respectively Both knee varus torques and mediolateral accelerations showed two distinct positive peaks in loading response and preswing. Medial wedges resulted in significantly increased both knee varus torque and lateral acceleration in loading response, compared with the barefoot walking(p<0.05). On the other hand, lateral wedges decreased them in loading response(p<0.05). This became more significant for more inclined wedges. However, no significant correlations were found between knee varus torque and lateral acceleration according to the angle of heel wedges in preswing. From this study, it was found that a lateral wedge would be helpful to treat osteoarthritis, decreasing knee varus torque in loading response. In addition, lateral acceleration of the knee joint might be an alternative to determine the effect of wedges and the alignment of the knee joint during walking, instead of measuring knee torque by the three-dimensional motion analysis.

• Annals of Clinical Neurophysiology
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• v.7 no.1
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• pp.7-12
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• 2005

Background: Essential tremor (ET) is a common movement disorder that often causes functional disability. There have been very few investigations about the clinical characteristics of ET in Korea. Therefore, we performed a study showing the clinical features and electrophysiological findings of ET. Methods: We analyzed medical records and accelerometry data of 152 patients (male vs female; 79 vs 73) with ET, who visited the Neurology Clinic of Hospital from 2000 to 2003. Clinical characteristics of ET were summarized including the age of onset, family history, tremor type, body part involved, and associated symptoms. The frequency of tremor was recorded and the spectral analysis of tremor was performed. Results: The age of tremor onset showed bimodal distribution with peaks in the 2nd and 5th decades. Family history was found in 46 patients (30.3%). The patients with the family history presented earlier onset of tremor than patients without the history (mean age of onset, y: 35.2 vs. 49.9, P < 0.001). Tremor appeared most frequently in hands (94%), and followed by head (25%). In head tremor, "no-no" pattern was mainly observed and the head tremor was more frequently observed in female. The frequency of tremor was negatively correlated with age (r=-0.49, P<0.001). Conclusions: The present study indicated some important findings about ET: (1) bimodal distribution for an age of onset, (2) younger age of onset in patients with a family history, (3) decreasing frequency of the tremor according to age, and (4) higher prevalence of head tremor in female patients.

• Journal of Biomedical Engineering Research
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• v.30 no.3
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• pp.213-220
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• 2009

In this study, we have developed a novel step detection algorithm for gait evaluation of patients with hemiplegia based on trunk accelerometry device. For this, we have used a bandpass filter and a least square acceleration (LSA) filter which is characterized by emphasizing the peak or valley point of the acceleration signals for each 3-axis accelerometer signals. To evaluate the algorithm, the detected steps by developed algorithm and real steps by the motion analysis system were compared. As a result, we could obtain the sensitivity of 96.44%, the specificity of 99.94% and the accuracy of 99.90% for the patients' data sets and the sensitivity of 100%, the specificity of 99.93% and the accuracy of 99.93% for the normal data sets. In conclusion, the developed algorithm is useful for the step detection for patients with hemiplegia as well as normal subjects.

• Korean Journal of Exercise Nutrition
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• v.24 no.1
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• pp.29-36
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• 2020

[Purpose] The purpose of this study was to investigate the effects of short-term creatine intake on muscle fatigue induced by resistance exercise in healthy adolescent men, i.e., lactic acid concentration and wrist and head tremor measured by an accelerometer. [Methods] Twelve healthy adolescent men who had no experience with creatine intake were included. The subjects were randomly assigned to the creatine group and the placebo group, followed by 5 days of creatine and placebo intake, and 5 times of 5 sets of leg press, leg extension, bench press, and arm curl exercises at 70% repetition maximum (RM). The lactic acid concentration before and after exercising, rate of perceived exertion (RPE), and accelerometer-based wrist tremor and head tremor during exercise were measured. Subsequently, after 7 days to allow for creatine washout, the same exercise treatment and measurement were performed in each group after switching drug and placebo between the groups. [Results] The level of lactic acid before and after the acute resistance exercise trial was significantly lower in the creatine group than in the placebo group (P <0.05). The mean RPE during the resistance exercise was significantly lower in the creatine group than in the placebo group (P <0.05). There was no difference between the two groups in the mean wrist tremor during resistance exercise, but the mean head tremor values were significantly lower in the creatine group than in the placebo group in the arm curl, the last event of the exercise trials (P <0.05). [Conclusion] Short-term creatine intake reduces the blood fatigue factor increased by resistance exercise, and is thought to suppress fatigue, especially in the latter half of resistance exercise. Therefore, these findings indicate that short-term creatine intake can have an improved effect on anaerobic exercise performance.