• Proceedings of the ESK Conference
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• 1997.10a
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• pp.220-225
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• 1997

졸음에 의한 순간적 과오는 자동차운전을 비롯한 각종 산업안전에 인명피해를 포함하는 치명적 손실 을 수반한다. 따라서 이분야에 대한 연구가 국내를 포함한 전세계에서 활발히 진행되어 상업화가 추진 중이다. 그러나 이러한 연구는 실용적 차원에서 주로 피부전기활동(Electrodermal Activity: EDA)과 눈 깜박임 등의 측정방법에 의존하고 있으며 졸음의 첫 지시치로서 중요하고 객관적인 각성-졸음 과도기 뇌파를 포함하는 수면 다원생리신호 측정에 관한 연구는 이 방법이 피험자에게 구속성을 주고 측정 자체가 까다로워서 현실적으로어려운 실정이다. 본 연구에서는 그 동안 Medilog SAC847 Polysomnography를 이용한 수면에 관련된 종합적 생리신호를 측정.분석 연구해온 경험을 토대로 정상적인 성인의 각성-졸음 과도기 생리신호특징으로서 뇌전도(Electroencephalogram:EEG), 턱 및 다리근전도(Electromyogram:EMG), 심전도( Electrocardiogram:ECG), 안전도(Electrooculogram:EOG) 등을 종합적으로 분석한 결과 졸음상태가 각성상 태에 비하여 EEG의 주파수는 감소하고, EMG와 ECG의 진폭은 줄어들고, EOG에서는 느린 안구운동의 특징을 갖는 것을 알 수 있었다.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.209-216
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• 2018

This study aimed to investigate the association of the muscle activity around the neck of the operator(dental hygienists') according to the change in the patient's neck angle during a direct visual inspection on the maxillary right-side molar palatal surface. The operators were $4^{th}$ year dental hygiene students, who are future dentalhy gienists, having accurate understanding on and awareness of the location of the operation site, hand fixation, and how to use the tools. Data on the change in the muscle activity around the neck were collected by using surface electromyography and neck goniometer. SPSS statistics 20 was used for statistical analyses including Shapiro-wilk test and one-way ANOVA. As a result, the activities of the operator upper trapezius, cervical erector spinae, and levator scapulae muscles significantly decreased when the patient's head was angled compared to when it was not. For the angle of the operator head, the head bend significantly decreased when the patient's head was angled than when it was not. Based on the study results, it is expected that angling the patient's head when treating his or her teeth will decrease the excessive muscle activity around the neck of the operator, and will reduce muscle fatigue. Therefore, angling the head of the patient while treating his or her teeth is recommended. This suggests that muscle pain caused by repetitive actions in the wrong posture can be reduced.

• The Journal of Korean Physical Therapy
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• v.19 no.3
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• pp.11-17
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• 2007

Purpose: The purpose of this study were to analyze fatigue patterns of the rectus femoris muscle by isometric contraction. Methods: Twenty healthy subjects(10 male, 10 female) participated in this study. Maximal voluntary isometric contraction(MVIC) was measured by the dynamometer. Muscle activity was recorded from the rectus femoris muscle. During the experiment, the subject was seated in the chair. The measured items, median frequency(MDF) and root mean square (RMS), were collected from the surface EMG. All data were analyzed using repeated measures ANOVA. Results: There was significant difference of MVIC between male and female. Endurance time was significant difference by the level of MVIC but no significant in the main effect(sex) and interaction effect. The MDF and fatigue index were significant differences in the interaction effect. The RMS was not significant difference in both of main and interaction effect. The muscle fatigue patterns of female was greater than male after 60% MVIC. Conclusion: This study showed that sex differences of muscle fatigue were started from 60% MVIC.

• Journal of Korean Physical Therapy Science
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• v.19 no.4
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• pp.1-6
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• 2012

Purpose : The current research examines the muscle activity that happens during scaling practice subject to 20 dental hygienic students with musculoskeletal pain and then propose a basic data according to the working attitude of the Dental Hygienist. Method : The Nordic-style questionnaire is used to define experimental group with musculoskeletal pain and control group. During the scaling the surface EMG device is used to measure the muscle activity of experimental and control group. Study design : The surface EMG is measure RMS(root mean square) of suboccipital muscle, biceps brachii, upper trapezius, and brachioradialis muscle activity. Results : In the experimental group, the RMS of upper trapezius and brachioradialis is increased during scaling practice(p<0.05), but the control group's RMS is not changed(p>0.05). Conclusion : Musculoskeletal pain may contribute to increase muscle activity of neck & arm during scaling practice. In the future we think there is a need to raise the office efficiency by subjecting to dental hyginiest that are in the clinics and performing experiments.

• Physical Therapy Korea
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• v.9 no.4
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• pp.69-76
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• 2002

본 연구에서는 상부 승모근의 근막통증(myofascial pain syndrome; MPS)를 대상으로 이완상태에서 근 활성도를 측정해보고, 통증을 감소시키는 데 주로 이용되는 경피신경자극 치료 후 근 활성도에 어떠한 영향을 미치는지 알아보기 위해 실시하였다. 본 연구의 대상자는 근막 통증으로 진단을 받은 총 10명을 대상으로 실시하였다. 주관적 시각 척도(visual analogue scale; VAS)와 압통 역치 측정계(pressure threshold meter)를 이용하여 경피신경자극 전, 후 통증의 정도를 평가하였고, 표면 근전도를 이용하여 이완시 근 활성도를 측정하였다. 치료 기구는 경피신경자극기(TENS: HAT-2000)를 이용하였다. 치료 전과 비교하여 VAS는 통증이 심한 쪽과 약한 쪽 모두에서 유의하게 감소하였으며(p<.05), 압통 역치는 통증이 심한 쪽과 약한 쪽 모두에서 유의한 차이가 없었고(p>.05), 근 활성도는 통증이 심한 쪽에서 유의하게 감소하였다(p<.05).

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.81-85
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• 2009

Work related musculoskeletal disorders(WMSDs) was a leading cause of sick leave and injuries in the industries of our country. Posture was an important consideration in the design of work method and workplaces, because it affected the ability of workers to use various equipments and influenced how long they could perform their job without feeling discomfort, fatigue, and musculoskeletal disorders. Imbalanced lower limb postures such as a squatting posture were awkward working postures common to the shipbuilding shops, farms, automobiles assembly lines in our country. Different awkward working postures were known to be associated with specific musculoskeletal disorders. Eight postures in lower limb postures divided into balanced and imbalanced postures were evaluated by electromyographic(EMG) activity for lower limb muscles. Twelve male subjects participated in this study. This paper was to analyze the effects of lower limb muscles workload according to lower limb postures(knee angle) and working time. The ANOVA results showed that most EMG root mean square(RMS) values were statistically significant effect according to lower limb postures(knee angle) and working time. Therefore, the results of this study will provide the basis to evaluate workload of lower limb postures correctly adopted by workers in various jobs and the ergonomic reference to prevent WMSDs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.476-482
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• 2017

This study examined the effects of the seat height of a chair on the muscle activity of the erector spinae and rectus abdominis. Thirty healthy subjects were asked to sit on chairs at three different seat heights. The muscle activities of both the erector spinae and rectus abdominis were measured by surface electromyography. The data were analyzed by repeated one way ANOVA and the muscle activity was compared according to the seat height. The alpha level was set to 0.05. The results showed that the muscle activities of the erector spinae were not significantly different among the three seat heights. The muscle activities of the rectus abdominis were significantly different among the three seat heights. Both the rectus abdominis muscle activities were significantly greater in the low seat height than the other seat heights. These results showed that the seat height of the chair affects the muscle activities of the rectus abdominis muscle, leading to musculoskeletal pain, such as low back pain. Therefore, the seat height of a chair with a correct sitting position is important for preventing musculoskeletal pain.

• 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.

• 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 the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.169-174
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• 2005

Traditionally, keyboards have been one of the most frequently used input devices for information processing using computers. As most computers adopt the Microsoft Windows for their operating system however, the usage of mouse has recently increased to a great extent. Moreover, the mouse has been used as the leading input device in such areas as industrial design and computer aided design. Excessive uses of mouse may cause a severe pain and fatigue on neck and upper limb due to the intensive and repetitive use of corresponding muscles, which renders a decline in efficiency and leads to musculoskeletal disorders. The main purpose of this study is to find the best working conditions to prevent musculoskeletal disorders when using mouse in a neutral posture. Utilizing electromyogram amplitude and Borg's scale, the role change and strength imposed on the muscles were measured and analyzed with and without the forearm support concerned. Also investigated were the effects of changes in elbow forearm supporter.