• Title/Summary/Keyword: fatigue endurance

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The effect of aronia, montmorency, and Prunus mume supplementation on blood fatigue factors and muscle damage enzymes after running 10 km

  • Shin, Pan-Jun;Kim, Yeon-Hui;Lim, In-Soo
    • Korean Journal of Exercise Nutrition
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    • v.16 no.1
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    • pp.19-26
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    • 2012
  • The purpose of this study was to analyze the effects of intake of aronia, montmorency, and Prunus mume on 10 km endurance exercise by investigating changes in blood lactate, ammonia, creatine kinase (CK), and lactate dehydrogenase (LDH), and eventually to recommend them as ergogenic aids, which are effective for recovering from exercise fatigue and muscle damage. The subjects were divided into a P. mume intake group, an aronia intake group, a montmorency intake group, and a control group. Blood samples were taken from the brachial vein at rest, and at 0, 30 min, and 24 hr after running to measure recovery status. All data were analyzed by a two-way repeated-measures analysis of variance using SPSS. The results are summarized as follows: The changes in blood ammonia and LDH concentration following 10 km of running were not significantly different among the groups. However, lactate and CK recovery ratio increased significantly in the aronia and montmorency groups compared to those in the P. mume and control groups. In particular, CK concentration was significantly different in the montmorency group compared to that in the other groups. These results suggest that the effects of aronia and montmorency are associated with improved recovery from muscle fatigue and damage induced by highly intensive exercise, endurance exercise, or overtraining. In particular, montmorency is recommended as an ergogenic aid to inhibit muscle pain resulting from high-intensity endurance exercise.

Influence of Room Temperature and Strain Aging on the COD for a Small Fatigue Crack (室溫時效 및 變形時效가 微小 疲勞크랙의 開口變位에 미치는 影響)

  • 김민건
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.402-407
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    • 1995
  • The effects of room temperature and strain aging treatment are discussed on the critical condition for the onset of growth of non-propagating cracks on 0.15% C low carbon steel, with special emphasis on the length of the critical non-propagating crack and on the crack opening displacement(COD) at the crack tip. It is found from the experimental analysis that room temperature and strain aging of a fatigue pre-cracked specimen introduced the closure of a crack tip of the pre-crack and the reduction of crack opening displacement at the wake of crack, together with an improvement in crack growth resistance of the microstructure. This may cause an increase in the endurance limit of the specimen, through the enhancement of effective stress for the onset of growth of the critical non-propagating crack.

A Study on Estimation of Fatigue Performance of Polyethylene Boat (폴리에틸렌 보트의 내구성 평가에 관한 연구)

  • Oh, Jeong-Seok;Cho, Seok-Swoo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.1
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    • pp.47-54
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    • 2014
  • Endurance of ship hull can be estimated by existing regulations and fatigue estimation methods. These can be applied to the hull materials that are recommended by ship regulations but can't be applied to new materials. In this study, structural force in the worst sailing condition is obtained by the acceleration measurement test of small polyethylene boat and the endurance of small polyethylene hull is estimated by rainflow cycle counting method and linear cumulative damage rule. Maximum Von-Mises stress on the polyethylene boat is 1.8MPa and much lower than the fatigue strength of at least 5.9MPa for the fatigue life of $1{\times}10^9$ cycles. Fatigue life of the polyethylene boat hull is estimated to be 6,229 years.

The Effect of Yaksun Recipe with Korean Ginseng on Exercise Practice Ability and Fatigue Variable Factor. (인삼을 함유한 약선레시피가 운동수행능력 및 항피로에 미치는 영향)

  • Mi-Lim Kim;Soon-Ae Park;Min Ju Kim;Mi-Rae Shin;Seong-Soo Roh;Hae-Jin Park
    • The Korea Journal of Herbology
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    • v.39 no.3
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    • pp.97-105
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    • 2024
  • Objective : This study examined the effects of yaksun recipe on the anti-fatigue and endurance enhancement properties in the forced swimming test (FST). Methods : The treatment groups were divided randomly into three groups: water-treated FST (control), 200 mg/kg of red ginseng-treated FST (RG200), 200 mg/kg of water extract of yaksun recipe-treated FST (YS200). After FST, an autopsy was performed, and the tissue and serum were collected. Results : The swimming exhaustion time in the RG200 and YG200 groups were significantly increased compared to the control group. The YG200 group fatigue indicators, D-Lactate, LDH(lactate dehydrogenase), creatine kinase, and ammonia content, significantly decreased compared to the control group. In addition, liver glycogen content significantly increased in the YG200 and tended to increase in RG200. Likewise, the glucose contents were significantly increased compared to the control group. The muscle damage indicators GPT (glutamic pyruvic transaminase) and BUN (blood urea nitrogen), a protein metabolite, in the YG200 group significantly decreased compared to the control group. Furthermore the concentration of liver lipid peroxidation, MDA(malondialdehyde) levels significantly decreased in the RG200 and YG200 compared to control group. Conclusions : These results suggest that YG200 can increase the endurance exercise capacity by decreasing the fatigue indicators, saving glycogen, and elevating the antioxidant defense system.

A Study on Development of Fatigue Life Estimation Method for the Spider of a Drum Washing Machine with CAE (CAE를 활용한 드럼세탁기 Spider의 피로수명 평가기법 개발에 관한 연구)

  • Kim Ji-Seol;Kwak Dong-Hyun;Cho Sang-Bong;Kim Yeong-Su;Jeong Seong-Hae;Gang Dong-U;Jeong Yeon-Su;Jeong Bo-Seon
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1311-1314
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    • 2005
  • Recently drum washing machines are required to improve not only functions, but also endurance security. The spider is one of the major parts in a drum washing machine as a power transmission device. It is needed estimating for fatigue life because it rotates at high velocity when the drum washing machine works. In this study, we tried to estimate fatigue life of the Spider with CAE and verified the accuracy by comparing the CAE results with the experimental results. The estimation method of fatigue life for the spider with CAE will be applied to raise the efficiency of time and money in the design process of a new drum washing machine.

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The Study of Isometric Endurance Time by Task Type and Maximum Voluntary Contraction (작업형태 및 최대 수의적 수축에 따른 등척성 근지구력에 관한 연구)

  • Sim, Jeong-Hun;Lee, Sang-Do
    • Journal of the Ergonomics Society of Korea
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    • v.22 no.2
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    • pp.57-69
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    • 2003
  • This study was performed to investigate the isometric endurance time as percentages of maximum voluntary contraction. Electromyogram(EMG) and Borg's CR-I0 value were measured by push-pull-up-down tasks for 10 healthy males. The normalized EMG value and the MPF(mean power frequency) were used to estimate the muscle recruitment pattern and the development of muscle fatigue. The subjects exerted and maintained 5 levels of %MVC(maximum voluntary contraction) in $90^{\circ}$ shoulder flexion/ 180oelbow extension at sitting posture. The up-task showed the lower endurance time and higher Borg's CR-I0 value than the other task types. Comparing Rohmert's curve with the endurance time of task types. Rohmert's curve overestimated the endurance time of up-task and underestimated the endurance time of push-pull-down tasks. The normalized EMG value showed that muscles recruitment patterns were different from task types. The 4 muscles(biceps brachii muscle, tricep brachii muscle. middle deltoid muscle. trapezius muscle) recruitment patterns of up-task were higher than those of other tasks. The MPF value decreased with the endurance time, and the shift of MPF at up-task was larger than that of the other task types.

Performance of Cemented Carbides in Cyclic Loading Wear Conditions

  • Kubarsepp, J.;Klaasen, H.;Sergejev, F.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.887-888
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    • 2006
  • The present study describes the wear and mechanical behaviour of carbide composites in cyclic loading applications (blanking of sheet metal). Adhesive wear as well as fatigue endurance were tested, complemented by XRD studies. It was found that the blanking performance of a carbide composite is controlled by its resistance to adhesion wear and fatigue sensitivity. XRD studies revealed that fatigue damage is preceded by plastic strain in both phases of the composites

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Relationship between Endurance Times and Frequency Parameters in Surface EMG during Isotonic Contraction Exercises (등장성 수축운동시 표피근전도의 주파수파라미터와 근지구력시간과의 상관성)

  • Lee, Sangsik;Go, Jaewook;Jang, Jeehun;Park, Wonyeop;Lee, Kiyoung
    • Journal of Biomedical Engineering Research
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    • v.33 no.3
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    • pp.135-140
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    • 2012
  • Previous investigators have shown that the frequency compression is related to the muscle fatigue and the decreasing conduction velocity of muscle fibers. The aim of the present study was to investigate the relationship between endurance times and frequency parameters such as mean power frequency and median frequency in the surface EMG signal during isotonic contractions. Eight healthy subjects performed voluntary isotonic contractions of biceps Brachii muscle until their endurance times which were determined when the subject could no longer follow the contraction cycle. The regressive slopes of mean power frequency and median frequency were used to describe the frequency compression of the surface EMG signal, and to test the predictability of endurance time. As results of experiment, significant correlations were found between endurance time and the regressive slopes of mean power frequency and mean frequency computed over 50%Tend of endurance time.

Experimental Study on Shear Connector for Precast Concrete Decks

  • Chung, Chul-Hun;Shim, Chang-Su;Jeong, Un-Yong
    • KCI Concrete Journal
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    • v.13 no.1
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    • pp.61-67
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    • 2001
  • For the design of shear connection for the composite precast concrete slabs. it is necessary to investigate its strength, stiffness, slip capacity and fatigue endurance. For theme purposes, push-out tests were performed with variations of the stud shank diameter and the compressive strength of the mortar. From the experimental studies, it could be observed that the deformation of the shear studs in a full-depth precast concrete slabs were greater than those in a cast-in-place slabs. The static strength of the shear connections obtained agree approximately with those evaluated from the tensile strength of the stud shear connectors owing to the effect of the bedding layer between the slabs and the beams. An empirical equation for the initial shear stiffness of a shear connection was also proposed. On the basis of the push-out tests, a full-scale composite beams with 8.0m span was designed and fatigue tests were carried out to study the behaviour of the stud shear connection and its effects on the flexural behaviour of the beam. The bonding arid friction between the concrete slab and the steel beam considerably increased the fatigue endurance of the shear connection.

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