• Journal of Digital Convergence
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• v.11 no.11
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• pp.545-551
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• 2013

This study aimed to compare the effects of microcurrent stimulation and rest on the fatigue index by applying both to subjects who had accumulated fatigue after performing short-duration physical activity. The experiment was performed at S University from December 2012 to February 2013, on 22 healthy men in their 20s, who were right-handed, and without peripheral or musculoskeletal diseases. All subjects lifted a 10-kg box lift and lower 100 times in 15 minutes. Immediately after that, muscle fatigue index (Median Frequency: MF) and blood fatigue index (Creatine Kinase Lactate: CK, Lactate Dehydrogenase: LDH) were measured by using surface electromyography. The subjects were divided into two groups, and microcurrent stimulation and rest were mediated to the experimental and control groups, respectively, for 20 minutes. After intervention, muscle fatigue index and blood fatigue index were measured and the changes in the accumulated fatigue index were compared. Both groups manifested significantly decreased cumulative fatigue after applying the mediation compared to the pre-intervention level (p < .05), the only exception being the fatigue index of the left erector spinae in the rest group. Compared to the rest group, the microcurrent stimulation group showed a significant decrease in muscle fatigue index (p < .05) but no significant differences were found in the blood fatigue index. Given the results of this study, microcurrent stimulation is considered to be helpful in muscle fatigue recovery for workers who have to perform repetitive movements lifting weights, and additional studies on the correlations of the fatigue recovery with respect to the long-term follow-up of fatigue index and mediation time are necessary.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.4
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• pp.87-96
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• 1993

Spectrum analysis of surface electromyogram (FMG) signals is an effective approach to the study of localized muscular fatigue during isometric contraction. Many investigators have con firmed the frequency of the EMG signals being lowered during sustained contaction. In this study, the cyclic loading tasks were performed, and a comparison was made for the median power frequency shift pattern of the EMG signals with the sustained contraction of the same load. The median power frequency shift of the EMG signals for the cyclic loading task was found to be a part of that for the sustained contraction. Based on this result, a new muscle fatigue index was computed by normalizing the duration of the sustained contraction. A fatigue index was obtained as a function of exertion level and the work/rest schedule. With the proposed fatigue index, it is possible to evaluate or predict the degree of muscular fatigue for a physically demanding task.

• Korean Journal of Applied Biomechanics
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• v.22 no.3
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• pp.349-356
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• 2012

This study aimed to assess the effects of progressive lumbar stability exercises and lumbar stability exercises on changes in the transversus abdominis muscle thickness and lower extremity muscle fatigue index in soccer players. Ten subjects were assigned to undergo training in each of the 2 groups, namely, the progressive lumbar stability exercise group and lumbar stability exercise group. Each intervention session lasted for 30 min, and 4 sessions were conducted in a week for 6 weeks for soccer players of S. University in Jeonnam, Korea. Changes in the transversus abdominis muscle thickness and lower extremity muscle fatigue index were measured using ultrasound and surface electromyogram. The results of the ultrasound measurement for the transversus abdominis muscle thickness indicated that progressive lumbar stability exercises were more effective than lumbar stability exercises. The results of the lower extremity muscle fatigue index measurements using surface electromyogram indicated that the fatigue index decreased in the progressive lumbar stability exercise group. Progressive lumbar stability exercise is believed to have put more workload during the shaking of the limbs, leading to increased stability and increased efficiency of the lower extremity muscle, thereby decreasing the fatigue index. Therefore, progressive lumbar stability exercises can be an effective measure for preventing injuries and improving the game performance of sports players by increasing the transversus abdominis muscle thickness and decreasing the lower extremity muscle fatigue index.

• Journal of Korean Academy of Nursing
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• v.33 no.4
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• pp.478-487
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• 2003

Purpose. The purpose of this study was to identify the relationship between fatigue and nutritional status in patients undergoing radiotherapy. Design. A correlational and crossectional study design was used. Method. One-hundred-fifty-one subjects with cancer receiving radiotherapy were recruited from a university hospital in Chonan, Korea. Fatigue was measured using Piper's Fatigue Scale (PFS). The parameters for nutritional status included body weight, body mass index, hemoglobin, and lymphocyte counts. Cancer stage was controlled in analyzing the differences in fatigue, body weight and body mass index. Results. The patients who experienced most fatigue were in their fifties, employed, had head and neck cancer, received radiotherapy on the head and neck, and had concomitant chemotherapy. Disease-related characteristics such as cancer type, and treatment type were frequently related to poorer nutritional status. Patients who showed poorer nutritional status, such as those with lower body weight, lower body mass index and lower hemoglobin levels were more fatigued than those who did not exhibit such characteristics. Lymphocyte counts did not correlate with fatigue. Conclusion: The findings can be used by nurses who are taking care of patients undergoing radiotherapy. Considering the relationship between fatigue and nutritional status, nurses can identify the risk group most vulnerable to fatigue and malnourishment in order to provide appropriate interventions for them.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.143-151
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• 2016

Objective: The purpose of this study was to investigate the effect of fatigue induction on ground reaction force (GRF) components, postural stability, and vertical jump performance in Taekwondo athletes. Method: Ten Taekwondo athletes (5 men, 5 women; mean age, $22.30{\pm}2.62years$; mean height, $174.21{\pm}9.20cm$; mean body weight, $67.28{\pm}12.56kg$) participated in this study. Fatigue was induced by a short period of strenuous exercise performed on a motorized treadmill. The analyzed variables included vertical jump performance, static stability (mediolateral [ML], center of pressure [COP], anteroposterior [AP] COP, ${\Delta}COPx$, ${\Delta}COPy$, and COP area), postural stability index values (ML stability index [MLSI], AP stability index [APSI], vertical stability index [VSI], dynamic postural stability index [DPSI]), and GRF components (ML force, AP force, peak vertical force [PVF], and loading rate). To analyze the variables measured in this study, PASW version 22.0 was used to calculate the mean and standard deviation, while a paired t-test was used to evaluate the pre- versus post-fatigue results. Pearson's correlation coefficients among variables were also analyzed. The statistical significance level was set at ${\alpha}$ = .05. Results: Vertical jump performance decreased significantly after the induction of fatigue, while AP COP, ${\Delta}COPx$, COP area, APSI, VSI, and DPSI increased significantly. PVF and loading rate increased significantly after the induction of fatigue, while the postural stability variables (AP COP, ${\Delta}COPy$, COP area, APSI, VSI, DPSI) were similarly correlated with GRF components (PVF, loading rate) after fatigue was achieved (r = .600, $R^2$ = 37%). Conclusion: These results suggest that the induction of fatigue can decrease postural stability and exercise performance of Taekwondo athletes during training and competition sessions.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1109-1114
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• 2005

The rolling contact fatigue of wheels for high speed trains is a matter of increasing importance. The wheel damages from fatigue crack makes noise up and safety down. RCF-casued accidents cause traffic congestion and economical costs as well as personal injuries. In this study, we examine the rolling contact fatigue of wheels for power car running at 300km/h. Using the results of multi-body dynamic analysis and the proposed procedure of Ekberg, we calculate the fatigue index of surface-initiated fatigue, subsurface-initiated fatigue and fatigue initiated at deep material defects. As a result. the fatigue index shows us whether fatigue will appear and in which form. In addition, we present Shakedown map on surface-initiated fatigue.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.175-181
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• 2003

Studies of muscle fatigue have mostly been checked under isometric exercise. However EMG signals from isotonic exercise generate uncontrollable noise, so there were difficulties in gathering reliable median frequency and muscle fatigue index if frequency analysis was equally applied in isometric exercise. This study tried to compare the differences of muscle fatigue determinant variables in terms of median frequency searching methods of EMG signal, which was estimated in isotonic exercise. To accomplish this, we determined median frequency by using different FFT intervals and overlapping ration of consecutive FFT sections under the same EMG signal, and then searched for a linear regression line, and compared initial median frequency, slope, and muscle fatigue index which were variables under the linear regression line. In result of comparison, initial median frequency was more elevated as FFT exercise interval became larger. The slope of the linear regression line showed distinguishable decreasing tendency as FFT intervals were larger and overlapping sections were smaller. Significant tendency of muscle fatigue index in FFT interval was shown by high muscle fatigue index in specific FFT intervals.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.17 no.2
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• pp.122-130
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• 2013

Objectives This study investigated the relationship between exercise and health factors including vaso-aging degree, stress index, stress resistance, fatigue and activity of autonomic nerve system etc. Methods The subjects were 20,509 persons who had received health examination by Korean Medicine and submitted questionnaires about exercise history, for 8 months from March to November in 2011. The vaso-aging degree were measured by APG (Accelerated Photoplethysmograph). The stress index and resistance, fatigue and activity of autonomic nerve system were measured by HRV (Heart Rate Variability). We analyzed the relationship between exercise and various variables by chi-square test with SPSS ver. 19.0. Results Regarding the relationship between exercise and vaso-aging degree, stress index, stress resistance, fatigue and activity of autonomic nerve system, there were significant differences(p<0.05). Conculsions This study suggests that vaso-aging degree, stress index, stress resistance, fatigue and activity of autonomic nerve system are affected by exercise.

• The Journal of Internal Korean Medicine
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• v.29 no.1
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• pp.219-230
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• 2008

Objectives : Consumption is a chronic wasting disease, in oriental medicine concept. Fatigue is a common symptom experienced by many people who have consumption. However, there has been little study about the relationship between consumption and fatigue in the Oriental medicine. For this reason, we attempted to investigate the present status of fatigue of outpatients, and its relation with consumption index, public health practice index, Chalder fatigue scale and Subjective Symptoms of Fatigue Test. Methods : The subjects were 149 outpatients who complain fatigue between Nov. 1, 2006 and Oct. 31, 2007. We measured degree of consumption by consumption index. We measured degree of fatigue by Chalder fatigue scale and Subjective Symptoms of Fatigue Test. Public health practice were investigated by "Breslow's 7 health practice". Results : Studies have shown that a group who disregard public health practices have higher numerical value, in part of $q\grave{i}-x\bar{u}$, $xu\grave{e}-x\bar{u}$, and Physical symptoms than a group more concerned with public health practice. A group who has fatigue for a period over 6 months are more likely to be $q\grave{i}-x\bar{u}$, $y\bar{i}n-x\bar{u}$, Chalder fatigue scale, neuro-sensory symptoms than a group fatigued for less than 6 months. Among the subjects, 81 (55.5%) were considered as 'fatigue patients' by the Chalder scale. Chalder fatigue scale, according to the Subjective Symptoms of Fatigue Test, consumption also, The more increase of Subjective symptoms of fatigue test, the more of consumption scale. Conclusions : This study has shown that there is a link between consumption and fatigue. Moreover, oriental medicine's consumption is more concrete than fatigue scale, so consumption index will have wide application to the study of fatigue.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.130-136
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• 2003

A FQI(fatigue quality index) analysis using the concept of SF(severity factor) is performed to various shape of elliptical hole. FQI is fatigue quality index to estimate the dynamic SF from static SF by finite element analysis. Since the SF is affected by the location of cutout in plate and radius ratio, static SF is analyzed with finite element method and forms the equation of FQI for predicting a dynamic SF. To examine the validity, dynamic SF is measured by photoelastics and thermalelastics for an epoxy resin plate with various elliptical holes under dynamic load.