• 대한안전경영과학회지
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• 제11권3호
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• pp.79-85
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• 2009

In this study, the effects of psychosocial stress (box color and precision demand) on muscle activity were evaluated in laboratory setting. Eight subjects performed sagittally symmetric lifting tasks. Box color (yellow, black), precision demand (yes, no), and box weight (5%MVC, 10%MVC, 15 %MVC) were varied and surface EMG signals from seven muscles(medial deltoid right, biceps brachii right, lateral triceps right, latissimus dorsi right, erector spinae right, external oblique right, internal oblique right) were recorded. EMG signals were band-pass filtered($10{\sim}400\;Hz$), rectified, RMS smoothed and normalized (NEMG). Analysis of variance tests were conducted on the total NEMG (TNEMG: the sum of the seven muscles' NEMGs) and on the individual muscle's NEMGs. Box color had no effect on the TNEMG and on the seven muscles activities(p>0.05). When precision demand was required at the end point of lifts, the mean NEMG showed higher values than no precision demand conditions: TNEMG (14% increase) and medial deltoid(40% increase), biceps brachii(10% increase), lateral triceps(26% increase), latissimus dorsi(25% increase) muscles. Those increases showed more conspicuous as the box weight increased in the muscles of medial deltoid, lateral triceps, and latissimus dorsi.

• 한국전문물리치료학회지
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• 제14권2호
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• pp.21-28
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• 2007

The purpose of this study was to compare the onset times of muscle activities and the order of muscle firing in erector spinae, multifidus, rectus abdominis and biceps brachii during perturbation between subjects with and without work-related chronic low back pain (LBP). Twenty-nine subjects, 14 with and 15 without LBP, participated in this study. The muscle responses were measured by surface EMG (electromyography) during perturbation in eye opened and eye closed conditions. The EMG onset times of the erector spinae, multifidus, rectus abdominis and biceps brachii were similar between groups in eye closed condition. But the onset times of the erector spinae, multifidus, rectus abdominis were significantly delayed in subjects with LBP in eye opened condition. The results provide an evidence for impaired feed-forward control of the trunk muscles in subjects with LBP. Further studies are needed to identify whether the impaired feed-forward control of the trunk muscles is the contributing factor to LBP.

• 대한인간공학회지
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• 제34권1호
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• pp.11-18
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• 2015

Objective: The aim of this study was to understand the effects of phone weight on the typing performance and muscle recruitment in the neck and upper extremity while typing a text message with dominant hand. The iPhone4 and iPhone5 were compared due to their 28-gram differences in weight. Background: Too much use of a cellular phone can lead the musculoskeletal disorders in the upper extremity. Phone makers tend to make their new models bigger, lighter, faster and smarter. Method: Fourteen healthy volunteers without any history of neuromuscular disorders or ongoing pain who used their smartphone more than one year were recruited. A 112g phone (iPhone5) and a 142g phone (iPhone4) were used for typing the lyric of the Korean national anthem with their dominant hand. Typing duration, the typing error, the perceived fatigue, and preference was investigated. Muscle recruitment and the resting gap of neck (middle trapezius and levator scapula), shoulder (infraspinatus and mid deltoid), elbow (biceps brachii and brachioradialis), thumb (extensor and abductor policis brevis) were collected using surface electromyography. Typing error was counted and typing speed was calculated in characters per min. The data were analyzed using a paired t-test and chi-square (${\chi}^2$) analysis for the effects of phone weight on the typing performance parameters and muscle recruitment. Results: Typing text message with iPhone5 took longer but had less muscle recruitment in brachioradialis, and extensor policis brevis muscles. Lighter weight of iPhone5 made biceps brachii to rest less without increasing the mean %EMG. Conclusion/Application: Findings of this study can be valuable information for phone designers to develop more productive device and for smartphone users to prevent the musculoskeletal disorders in the upper extremities.

• 한국운동역학회지
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• 제13권1호
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• pp.95-108
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• 2003

The purposes of this study were to analyze the muscle activities and the characteristics of muscle recruiting patterns of upper trunk for Ssirum dutguri technique using three top-ranked elite Ssirum players. The EMG technique was used to record muscle activities of both right and left sides of latissimus dorsi, biceps brachii, and erector spinae. Six surface electrodes were placed on the surface of the selected muscles and one ground electrode was also attached on the back of neck(C7). One video camera was also used to record the Ssirum motion to define 4 events and 3 phases for further analysis. The raw EMG data were filtered with band pass filter (50-400 Hz) to remove artifacts and then low pass filtered (4 Hz) to find the linear envelope which resemble muscle tension curve. This filtered EMG data were normalized to MVIC for the purpose of comparion between the subjects. The results were indicated that each subject with different physical characteristics showed very different muscle activity patterns. Although Ssirum dutguri is considered as foot technique the player grasped opponent's satba(belt) with both hands when they play. Because of this reason, activities of upper trunk muscles were relatively high. However, direct comparison between upper and lower body muscles was not possible due to the lack of the data in present study. Interestingly, all threes subjects showed that erector spinae muscle activity was comparatively higher than those of latissimus dorsi and biceps brachii. This implies to reinforce back muscle as a routine of training to improve performance or to prevent back injury.

• 한국철도학회논문집
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• 제10권5호
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• pp.576-581
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• 2007

본 연구는 기관사가 지하철 가/감속 장치인 마스콘을 구동 할 때의 시간에 따른 근피로도 변화를 근전도를 이용하여 측정 및 분석하였다. 기관사들은 대부분 하루에 평균 4시간 정도를 상지를 이용하여 마스콘을 구동한다. 4개의 근전도 채널을 상지의 어깨세모근(deltoid muscle), 위팔노근(brachioradialis muscle), 위팔 두갈래근(biceps brachii muscle) 그리고 자쪽 손목 굽힘근(flexor carpi ulnaris muscle)에 부착하여 각 상황에 따른 근전도 신호를 중앙주파수(MF)를 구하여 그 피로도를 분석하였다. 분석결과, 운행 30분 후 10명의 피험자(실제 기관사)의 80%이상의 중앙주파수 값이 유의하게 감소하였다. 이 결과는 30분의 마스콘 구동만으로도 기관사의 상지 근육에 피로를 유발함을 의미한다.

• 한국운동역학회지
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• 제30권4호
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• pp.311-319
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• 2020

Objective: The purpose of this study was to examine of this study is to study the effect of squat exercise on muscle activation in a sling device using various types of ropes and to propose an effective sling exercise method for strengthening the lower extremity strength. Method: 20 adult male subjects (age: 25.2±2.4 yrs, height: 176.5±3.2 cm, weight: 77.2±4.5 kg) participated in this study. In the experiment, a total of four squats were conducted: squat [SE], sling squat using inelastic rope [IR], sling squat using elastic rope [ER], and sling squat using two elastic ropes [TER]. Squats were performed 5 times for each condition, and a 60-second break was given for each condition to minimize muscle fatigue. The activation of biceps brachii, rectus femoris, gastrocnemius, and tibialis anterior muscles was measured. Results: It was found that the activation of all muscles was the lowest during the squat exercise [SE]. During the sling squat using inelastic rope [IR], the muscle activation of the biceps brachii was the highest. During the sling squat using elastic rope [ER], the activation of the rectus femoris, gastrocnemius, and tibialis anterior muscles was found to be the highest. In the sling squat using two elastic ropes [TER], most of the muscle activation was similar to that of the sling squat using inelastic rope [IR]. Conclusion: Our results of the experiment, it was found that sling squat exercise using elastic rope had a positive effect on the activation of all muscles. It is thought that performing a squat exercise under moderate weight load and unstable conditions, such as sling squat exercise using elastic rope, can increase the muscle activity of the lower limbs and perform more effective exercise effect than performing a conventional squat exercise under stable conditions. In the future, if research is conducted not only on adult men, but also on various ages and patients, it will be able to provide positive help in improving balance, stability and stamina through squat exercise.

• Journal of Animal Science and Technology
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• 제65권3호
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• pp.511-518
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• 2023

This study examined the association between functional sequence variants (FSVs) of myosin heavy chain 3 (MYH3) genotypes and collagen content in a Landrace and Jeju native pig (JNP) crossbred population. Four muscles (Musculus longissimus dorsi, Musculus semimembranosus, Musculus triceps brachii, and Musculus biceps femoris) were used for the analysis of meat collagen content, and the same animals were genotyped for the FSVs of the MYH3 gene by using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Three FSVs of MYH3 genotypes were identified and had genotype frequencies of 0.358, 0.551, and 0.091 for QQ, Qq, and qq, respectively. QQ animals for the FSVs of the MYH3 genotypes showed higher collagen content in their M. longissimus dorsi (p < 0.001), M. semimembranosus (p < 0.001), M. triceps brachii (p < 0.001), and M. biceps femoris (p < 0.001) than qq homozygous animals. After the validation of this result in other independent populations, the FSVs of MYH3 genotypes can be a valuable genetic marker for improving collagen content in porcine muscles and can also be applied to increase the amount of collagen for biomedical purposes.

• Journal of Animal Science and Technology
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• 제46권3호
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• pp.405-414
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• 2004

본 연구는 한국 재래돼지의 도축전 절식과 숙성이 longissimus dorsi(LD), biceps femoris(BF) and triceps brachii(TB)의 육질에 미치는 영향을 조사하였다. 18 시간동안 절식은 LD에서 유의적으로(P < 0.05) 높은 최종 pH을 보였고, BF도 유사한 경향을 나타냈다. 근육 온도는 절식유무에 영향을 받지않아, 이 결과는 각 처리구의 돼지들은 각기 다른 온도와 pH의 영향을 받았다는 것을 의미한다. 이러한 영향은 LD의 경우 절식을 하지 않은 돼지에서 유의적으로 높은(P < 0.05) hunter $L^*$ 값과 가열감량에서 나타났다. 하지만 전단력은 차이가 없었다. 또한 BF와 TB의 육질은 도축전 절식유무에 의해 영향을 받지 않았다. LD에서 전단력은 숙성 7일까지 감소하였고, BF와 TB는 14일까지 유의적으로(P < 0.05) 감소했다. 숙성기간중 LD와 BF, 그리고 LD와 TB의 상관관계를 보았을 때, LD의 전단력 6kg은 BF와 TB에서 각각 6과 3.5 kg을 보였다. 본 연구의 결과에 따르면, 도축전 급여는 시각적인 육색은 개선하나, 가열감량을 증가시켜 맛은 감소시킬 것으로 판단되었다. 한편 LD의 숙성은 7일이 적절한 것으로 나타났고, TB와 같이 근본적으로 연한 고기는 숙성은 가열감량을 증가시키므로 숙성하지 않는 것이 바람직하다고 판단되었다. BF와 TB에서는 14일 숙성은 연도는 증가하나 다즙성은 감소할 것으로 판단되었다.

• PNF and Movement
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• 제14권1호
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• pp.49-52
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• 2016

Purpose: The purpose of the present study was to examine the effects of the area of the base of support formed by the human body on the maximal voluntary isometric contraction of upper limb muscles. Methods: The study was conducted with 20 normal adults. To identify changes in the base of support, the maximal voluntary isometric contraction of the biceps muscle was measured in a standing position, a sitting position, and a lying position for each subject. The sizes of the base of support formed in the standing, sitting, and lying positions were set to 1, 2, and 3 respectively, based on the sizes, to analyze the correlations. The maximal voluntary isometric contraction of the biceps muscle was measured using surface electromyograms (EMGs) (Noraxon DTS, Germany). Results: The results showed negative correlations in which, as the size of the base of support increased, the maximal voluntary isometric contraction of the biceps muscle decreased. Conclusion: Changes in the base of support of the body affect the maximal voluntary isometric contraction of the upper limbs. Therefore, when resistance exercises are applied for muscle strengthening, the positions should be changed considering the changes in muscle activity according to those positions. In addition, when EMGs are used to measure the maximal voluntary isometric contraction, the measurements should be conducted in the same positions, considering muscle activity that changes according to the base of support and positions, for data quantification.

• 한국정보전자통신기술학회논문지
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• 제5권1호
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• pp.20-25
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• 2012

표면근전도의 중앙주파수 특징을 이용하여 근지구력시간에 대한 남녀 성별차별을 구분할 수가 있다. 중앙주파수는 근육의 피로속도를 측정하는데 주로 사용하는 인자이다. 본 연구에서는 상완이두근의 등장성 운동을 통한 근전도의 성별차이를 알아보았다. 등장성운동은 피실험자가 근육피로가 피곤해 질 때까지를 측정하였다. 남녀 성별차이는 근지구력시간에 대한 중앙주파수의 선형회귀선의 기울기로 구분되어지는 특성을 보였다.