• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.771-782
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• 2017

This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.

• Journal of Nutrition and Health
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• v.50 no.6
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• pp.552-564
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• 2017

Purpose: The purpose of this study was to measure energy expenditure (EE) the metabolic equivalents (METs) of 13 common physical activities by using a portable telemetry gas exchange system ($K4b^2$) and to assess the accuracy of the accelerometer (Actigraph $GT3X^+$) by gender in Korean adults. Methods: A total of 109 adults (54 males, 55 females) with normal BMI (body mass index) participated in this study. EE and METs of 13 selected activities were simultaneously measured by the $K4b^2$ portable indirect calorimeter and predicted by the $GT3X^+$ Actigraph accelerometer. The accuracy of the accelerometer was assessed by comparing the predicted with the measured EE and METs. Results: EE (kcal/kg/hr) and METs of treadmill walking (3.2 km/h, 4.8 km/h and 5.6 km/h) and running (6.4 km/h) were significantly higher in female than in male participants (p < 0.05). On the other hand, the accelerometer significantly underestimated the EE and METs for all activities except descending stairs, moderate walking, and fast walking in males as well as descending stairs in females. Low intensity activities had the highest rate of accurate classifications (88.3% in males and 91.3% females), whereas vigorous intensity activities had the lowest rate of accurate classifications (43.6% in males and 27.7% in females). Across all activities, the rate of accurate classification was significantly higher in males than in females (75.2% and 58.3% respectively, p < 0.01). Error between the accelerometer and $K4b^2$ was smaller in males than in females, and EE and METs were more accurately estimated during treadmill activities than other activities in both males and females. Conclusion: The accelerometer underestimated EE and METs across various activities in Korean adults. In addition, there appears to be a gender difference in the rate of accurate accelerometer classification of activities according to intensity. Our results indicate the need to develop new accelerometer equations for this population, and gender differences should be considered.

• Journal of Korean Biological Nursing Science
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• v.2 no.2
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• pp.1-19
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• 2000

The purpose of this study was to identify the characteristics and physiological variables of chest pain induced by exercise test in angina suspected patients. The subjects of this study consisted of 28 inpatients and outpatients aged between 40 and 75 who underwent treadmill test at exercise testing laboratory of S-University from January 2000 to June 2000. Subjects were interviewed with questionnaire regarding sociodemography, the past health history and history related to chest pain before the exercise test. Subjects were interviewed with questionnaire concerning quality, intensity, duration of chest pain induced by walking on the treadmill(Marquette, U.S.A. 1992) according to Bruce protocol following exercise test. Systolic and diastolic blood pressure were measured before, during and after the test, heart rate was determined by ECG. The results of this study were as follows ; 1) Quality of chest pain induced by exercise test were feeling stiffness 19(67.9%), heavy 10(36.0%), exploded 9(32.1%), crushing, suffocating, tight 8(28.6%), stuffy, prickly 7(25.0%), burning 6(21.4%), clasp 5(17.9%), cleaved, tensed, piercing 3(10.7%), perfectly fitting, sore 2(7.1%), tearing, tingling, ticklish, heartburn 1(3.6%). 2) Mean score of VAS(intensity of pain) following exercise test was $5.79{\pm}2.27$ and mean duration of chest pain after the test was $7.83{\pm}5.31$ minutes. 3) Sites of chest-pain induced by exercise test were middle site 11(39.3%), left-chest 10(35.6%), right-chest 6(21.5%). Radiation site of chest-pain was neck(18.0%), right flank site 1(3.6%), left shoulder & arm 2(7.1%) and back 1(3.6%). 4) Symptoms other than chest-pain induced by exercise test were dyspnea 21(75.6%), perspiration 14(50.4%), fatigue 12(43.2%), leg-pain 11(39.6%), dizziness 7(25.2%) anxiety toward chest-pain 3(10.8%), thirst 2(7.1%), and palpation, headache and tingling sensation of hand and leg 1(3.6%). 5) Mean MET(intensity of exercise) during the exercise test was $7.64{\pm}2.57$ and mean RPE(rating of perceived exertion) was $15.89{\pm}2.36$. Mean duration of exercise was $6.79{\pm}2.88$. 6) correlation coefficients between RPE and VAS was 0.500(p=0.003), those between MET and VAS was 0.287(p=0.069) and those between either depression or elevation of ST segment and VAS was 0.236(p=0.114). 7) There was a significant difference in mean systolic pressure between before and after the test as $146.29{\pm}28.18mmHg$ and $177.96{\pm}28.82mmHg$(t=-5.640, p=0.000), a significant difference in mean diastolic blood pressure between before and after the test as $84.85{\pm}15.07mmHg$ and $88.89{\pm}13.72mmHg$(t=-2.082, p=0.047), and there was a significant difference in mean heart-rate between before and after the test as $81.89{\pm}12.22/min$ and $160.68{\pm}21.77/min$(t=-21.255, p=0.000).

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.115-124
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• 2008

The purpose of this study was to examine the effects of customized foot orthotics on lower extremity muscle activity and fatigue during march in combat boots. Four volunteers with normal foot and five volunteers with excessive pronation foot among soldiers on service were fitted with foot orthotics. The electromyography signal from activity of low extremity muscles were collected with surface electromyography device during walking on the treadmill. The walk on the treadmill was performed with a speed of 4.5 km/h. The experiment design for reseach wes composed two experimentation. The first experiment was to examine the muscle activity of lower extremity between normal foot and excessive pronator foot during march. The second experiment was to examine the muscle activity of lower extremity between wearing orthotics and no wearing orthotics. These data were analyzed by the averaged integral EMG and the mean power frequency. The analyzed results were compared by independent T-test method and paired T-test method of SPSS(windows version 12.0). The result of the study were the muscle activity on pronator foot tend to increase during march but a statistically significant increase in muscle fatigue of vastus lateralis and fibularis longus. A statistically significant decrease in muscle activity of anterior tibialis and fibularis longus and fatigue occurred using the customized foot orthotics in volunteers with excessive pronation foot compared to volunteers with normal foot. Clinically, the application of orthotics for the soldiers with excessive pronation foot appears to delay muscle fatigue and prevent from variable foot injuries. This may contribute to enhancing fighting efficiency.

• Korean Journal of Community Nutrition
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• v.22 no.5
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• pp.413-425
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• 2017

Objectives: Accurate assessment of energy expenditure is important for estimation of energy requirements in athletic children. The objective of this study was to evaluate the accuracy of accelerometer for prediction of selected activities' energy expenditure and intensity in athletic elementary school children. Methods: The present study involved 31 soccer players (16 males and 15 females) from an elementary school (9-12 years). During the measurements, children performed eight selected activities while simultaneously wearing the accelerometer and carrying the portable indirect calorimeter. Five equations (Freedson/Trost, Treuth, Pate, Puyau, Mattocks) were assessed for the prediction of energy expenditure from accelerometer counts, while Evenson equation was added for prediction of activity intensity, making six equations in total. The accuracy of accelerometer for energy prediction was assessed by comparing measured and predicted values, using the paired t-test. The intensity classification accuracy was evaluated with kappa statistics and ROC-Curve. Results: For activities of lying down, television viewing and reading, Freedson/Trost, Treuth were accurate in predicting energy expenditure. Regarding Pate, it was accurate for vacuuming and slow treadmill walking energy prediction. Mattocks was accurate in treadmill running activities. Concerning activity intensity classification accuracy, Pate (kappa=0.72) had the best performance across the four intensities (sedentary, light, moderate, vigorous). In case of the sedentary activities, all equations had a good prediction accuracy, while with light activities and Vigorous activities, Pate had an excellent accuracy (ROC-AUC=0.91, 0.94). For Moderate activities, all equations showed a poor performance. Conclusions: In conclusion, none of the assessed equations was accurate in predicting energy expenditure across all assessed activities in athletic children. For activity intensity classification, Pate had the best prediction accuracy.

• Journal of Korean Physical Therapy Science
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• v.18 no.2
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• pp.51-62
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• 2011

Purpose: The purpose of this study was to investigate the effect of microcurrent on fatigue of muscles in people who were flat-footed during gait. Methods: 10 flat-footed university students volunteered to participate in this study. 10 flat-footed subjects were divided into 2 groups, one group was experimental group of 5subjects(This group put on microcurrent induction shoes but the subjects were not able to feel the current.) and the other group was the control group of 5subjects(This group put on the general shoes which were similar in shape but microcurrent was not induced.) to perform double blind test and random sampling. Their gait muscle fatigue of 6 regions (vastus medialis, gastrocnemius, tibialis anterior, biceps femoris, erector spinae, and rectus abdominis muscle.) was measured by EMG MP150, Delsys Inc Boston, USA during walking and then they carried out the Harvard step with a platform (It was a arbitrarily made wooden platform of 100cm long, 50cm wide, 60cm high. They carried out climbing it for one second and descending it for one second by using the Metronome program, total 5minutes) for 5minutes. Right after that, the subjects walked on a treadmill at a speed of 4km/h for 10minutes and then their gait muscle fatigue of 6regions was assessed while they were walking on the ground as equally as before exercise. Results: The experimental group has resulted in lower average differences in gait muscle fatigue before and after exercise than those of the control group average 12.24Hz(P=0.009) at vastus medialis, average 8.52Hz(P=0.016) at gastrocnemius, average 9.16Hz(P=0.009) at tibialis anterior, average 8.66Hz(P=0.047) at biceps femoris, average 7.53Hz(P=0.016) at erector spinae, and average 7.80Hz(P=0.047) at rectus abdominis. All of the assessments of muscles have shown significant difference statistically. Conclusions: This result has shown that the use of micro current could decrease gait muscle fatigue of flat-footed people. It is recommended to use a microcurrent to reduce their gait muscle fatigue.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.113-122
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• 2015

Objective : The purpose of this study was to analyze the foot-pressure distribution of 2D(2 dimensional form) & 3D(3 dimensional form; a customized arch-fit for posture correction) insoles for assessing their biomechanical functionality. Background : Recently there has been increased interest in both foot health and foot pain patients. Analysis of the plantar pressure was often used to solve the problems of the foot displayed by such people as rheumatoid arthritis patients. Method : Subjects who participated in this study were 17 female university students who had no previous injury experience in lower limbs and a normal gait pattern. The shoe size of all subjects was 240 mm. Two models of insoles of 2D(typical flat insole - 2 dimensional form) and 3D(special production - 3 dimensional form) were selected for the test. Using the Pedar-X system and Pedar-X insoles, 4.0 km/h of walking speed, and a compilation of 50 steps walking stages were used to analyze foot-pressure distribution. Results : Results of the foot-pressure distribution and biomechanical functionality on each insole were as follows; analyses of mean plantar pressure, maximum plantar pressure, maximum vertical GRF, and plantar pressure curve shape all showed overall low plantar pressure and GRF. Conclusion : This can be evaluated as an excellent insole for low levels on the plantar pressure and GRF. Therefore, it is possible to conclude that according to this analysis the 3D Customized Arch-fit Insole was better than 2D insole on the basis of these criteria.

• The Journal of Korean Physical Therapy
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• v.18 no.1
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• pp.1-10
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• 2006

Purpose: This study was to investigate how induced microcurrent shoes affect relief of feet pain, which often occurs to persons who are more than fifty years old and how they prevent fatigue of feet generated during everyday life. The subjects of this study were comprised af five males and five females, who agreed with this research and ate more than fifty years old. And they all have plantar faciitis and pain in their feet. Methods: Subjects ware the induced microcurrent shoes far more than 4 hours everyday during the test. When they wore those shoes, they also wore the specially produced shacks made of silver-mixed thread and they were asked to avoid serious exercise. Prior to starting test and after the test, assessments were carried out two times. In the examination before the test, general shoes were used and in examination after the test, induced microcurrent shoes used. Muscle fatigue was measured by electromyography(MP150, Biopac, USA). When the walking rate of subjects on a treadmill was increased from 2.Km/h to 3Km/h for 10 minutes, muscle activities of a lower leg were measured during the whale walking process by MP150 remote monitoring system(TEL 100C). And pain was measured by VAS. Results: The results are as follows. 1. Comparisons of VAS before and after experimentation showed that degree of pain was significantly decreased(p < .05). 2. Degree of fatigue of Tibialis anterior was significantly decreased after 6 weeks of treatment(p < .05). 3. Degree of fatigue of Soleus was slightly decreased after 6 weeks of treatment, but did not show significant difference (p > .05). Conclusion: The above results suggest that induced microcurrent shoes is helpful decreasing fatigue of feet and relief of feet pain.

• The Journal of Korean Physical Therapy
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• v.29 no.1
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• pp.33-38
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• 2017

Purpose: This study was conducted to investigate the effects of variations in arm swing during gait on movement of the trunk and pelvis. During the gait task, the angle of the trunk and pelvic rotation were analyzed according to arm swing conditions. Methods: Seventeen healthy males participated in this study. All subjects were analyzed for gait on a treadmill three times each under three different types of arm swing conditions - natural arm swing, restricted arm swing using a phone, restricted swing in both arms. 3-D motion analysis systems were used to collect and analyze the kinematic data of trunk and pelvic movements, and repeated one-way ANOVA was used to compare the trunk and pelvic kinematic data and symmetry index. The level of significance was ${\alpha}=0.05$. Results: The results showed kinematic differences in trunk and pelvic during gait based on the arm swing conditions. Specifically, there were significant differences in trunk rotation, left and right trunk rotation and symmetry index of trunk rotation during gait among the three arm swing conditions. ROM was used to calculate a symmetry index (SI) based on the average left and right trunk rotation in which a value closer to zero indicated better balance. The SI obtained for arm swing restricted with the phone was closer to -1 than the other conditions. Conclusion: Restricted arm swing due to use of a phone had the possibility to induce instability of postural control while walking, which could be seen to suggest a risk of falling during gait.

• Journal of the Korean Society of Physical Medicine
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• v.6 no.4
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• pp.489-496
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• 2011

Purpose : The purpose of this study was to identify the effect of an arch support taping on navicular drop height and plantar pressure in the subjects with excessive pronated foot for 6 weeks. Methods : The fifteen subjects with the pronated foot group and the fifteen subjects with the normal foot group volunteered for this study. Both groups were applied arch support taping at 3 times a week during 6 weeks. Subjects were assessed navicular drop test to evaluate pronation of subtalar joint and plantar pressure on treadmill for pressure measuring system during walking with a bare foot state at pre- taping, after 3 weeks, and after 6 weeks. A two-way repeated analysis of variance design was used to examine the difference of navicular drop height and plantar pressure in the pronation foot group and the normal foot group. Results : The pronated foot group had significantly decreased both the navicular drop height and the plantar pressure under the medial midfoot than the normal foot group after 6 weeks(p<.01). Conclusions : This study proposed that an arch support taping can be support to lift navicular bone as well as to transfer the foot pressure from medial midfoot to lateral midfoot in individuals with excessive pronated foot.