• 대한간호학회지
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• 제27권1호
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• pp.96-108
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• 1997

The purpose of this study was to determine the effect of endurance training prior to occurrence of muscle atrophy on the mass, myofibrillar protein content and fiber crossectional area of atrophied hindlimb muscles of rats. Adult female Wistar rats were trained prior to occurrence of muscle atrophy induced by hindlimb suspension. Training began on the 1st day for 10min /day at 15m /min on a 0% grade, training exercise increased daily in time and intensity so that by the 4th week rats were running 60min /day, at 34m /min on a i3.5% grade. Wet weight and relative weight of soleus, plantaris and gastrocnemius muscle decreased significantly after seven days of hindlimb suspension. Wet weight and relative weight of soleus tended to increase and that of plantaris and gastrocnemius tended to decrease in the exercise group as compared to the control group. Myofibrillar protein content of soleus and gastrocnemius tended to increase and that of plantaris tended to decrease in the endurance trained group as compared to the control group. Fiber crossectional area of Type I, II fiber in soleus and plantaris muscle tended to increase in the exercise group as compared to the control group. Wet weight and relative weight of soleus. plantaris and gastrocnemius decreased significantly, myofibrillar protein content of soleus, plantaris and gastrocnemius increased in hindlimb suspended rats following endurance training as compared to the control group. There was no change in fiber type percentage and crossectional area of type I and II fiber in soleus muscle and that of type I and IIfiber in plantaris muscle decreased in the hindlimb suspended rats following endurance training as compared to the control group. Wet weight and relative weight of soleus and plantaris tended to increase, that of gastrocnemius increased significantly, myofibrillar protein content of soleus and plantaris muscle increased significantly and that of gastrocnemius tended to increase in the hindlimb suspended rats following endurance training as compared to sedentary rats following endurance training. Crossectional area of type I fiber of soleus muscle tended to increase. that of type I fiber of plantaris muscle increased significantly and that of type II fiber tended to increase in hindlimb suspended rats following endurance training as compared to sedentary rats following endurance training. The results suggest that endurance training prior to occurrence of muscle atrophy can attenuate the decrease of mass, myofibrillar protein content and fiber crossectional area induced by hindlimb suspension.

• 한국전문물리치료학회지
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• 제2권1호
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• pp.51-61
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• 1995

In general, research in isokinetic exercise has focussed on studies of peak torque. However, peak torque is not always sufficient to assess the real amount of motion or to determine endurance. In this study, the subjects were 54 healthy students who performed continuous maximal isokinetic knee flexion and extension until their total work per time reached 50% of their maximal total work. Isokinetic curves were then plotted. Total work sums, exercise durations in seconds, and the numbers of repetitions were compared with reference to subject gender, angular velocity and muscle group. The relationship between total work sum, duration and number of repetition and thigh circumference plus leg length was computed. In addition, the characteristics of total work per second and total work per time were calculated. Results showed the total work sums differed greatly from muscle group to muscle group and with different angular velocities. The duration in seconds and the numbers of repetition differed only at higher angular velocity. Males achieved higher levels in every category except for some duration in seconds and some numbers of repetitions. Thigh circumference and leg length were deciding fators in every case, but duration in seconds and number of repetitions were not. These results suggest that measures of endurance should be included along with measures of total work when isokinetic studies are done. Measures of endurance in seconds are more accurate when isokinetic exercise is performed at lower angular velocities and numbers of repetitions at higher angular velocities.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1979-1985
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• 2003

Fretting is a kind of surface degradation mechanism observed in mechanical components and structures. The fretting damage decreases in 50-70% of the plain fatigue strength. This may be observed in the fossil power plant and the nuclear power plant used in special environments and various loading conditions. The thermal degradation of material is observed when the heat resisting steel is exposed for long period time at the high temperature. In the present study, the degraded 1Cr-0.5Mo steel used for long period time at high temperature (about 515$^{\circ}C$) and artificially reheat-treated materials are prepared. These materials are used for evaluating an effect of thermal aging on the fretting fatigue behavior. Through the experiment, it is found that the fretting fatigue endurance limit of the reheat-treated 1Cr-0.5Mo steel decreased about 46% from the non-fretting fatigue endurance limit, while the fretting fatigue endurance limit of the degraded 1Cr-0.5Mo steel decreased about 53% from the non-fretting fatigue endurance limit. The maximum value of fatigue endurance limit difference is observed as 57%(244 MPa) between the fretting fatigue of degraded material and non-fretting fatigue of reheat-treated material. These results can be a basic data to a structural integrity evaluation of heat resisting steel considered to thermal degradation effect.

• Physical Therapy Rehabilitation Science
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• 제9권3호
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• pp.149-154
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• 2020

Objective: This study aimed to evaluate the effects of the Kaltenborn-Evjenth concept of nerve mobilization combined with intermittent cervical segment traction (ICST) on pain, Neck Disability Index (NDI) scores, range of motion (ROM) and endurance in persons with cervical radiculopathy (CR). Design: Two-group pretest-posttest design. Methods: Thirty subjects participated in this study and were randomly assigned to two groups. The ICST group (n=15) was performed simultaneously with nerve mobilization and cervical traction for the segment with cervical pain at the same time. The intermittent cervical total traction (ICTT) group (n=15) performed nerve mobilization and cervical traction for the whole cervical area at the same time. In this study, outcome measures such as the Visual Analog Scale (VAS), NDI, ROM, endurance (cranio-cervical flexion test), and passive intervertebral motion performed before and 4 weeks after the experiment were compared to investigate the effects of each intervention. Results: In both groups, there were significant differences in the VAS, NDI scores, and endurance, and there were significant differences between the two groups except for endurance (p<0.05). In the ICST group, significant differences were found in all ROM, and in the ICTT group, significant differences were found in only extension, and there were significant differences between the two groups (p<0.05). Conclusions: The ICST group showed more improvement than the ICTT group in pain, NDI scores and ROM. Moreover, our findings show that the ICST could be used as a new strategy for manual therapy in persons with CR.

• 대한통합의학회지
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• 제9권1호
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• pp.123-131
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• 2021

Purpose : The time spent using smart devices is constantly increasing, particularly in recent times. Using smart devices for a long time with an incorrect posture may lead to cerebral palsy (CP), instability, and abnormal muscle tone. Therefore, we aimed to investigate the relationships among cervical instability, deep neck flexor (DNF) activity, range of motion (ROM), and muscle tonus. Methods : Fifty subjects with CP participated in this study, and they were physiotherapists at W Hospital in Daejeon. Those who voluntarily participated in the research were selected as candidates who fulfilled the selection criteria. According to an instability test, 25 subjects were assigned to the instability and control groups. All subjects first underwent the instability test to be allocated to the appropriate group. Those in the instability group tested positive on the instability test. The Neck Disability Index (NDI), ROM, muscle tone, and DNF activity were measured to evaluate their relationships. The DNF strength and endurance were measured using a cranio-cervical flexion test. The upper trapezius (UT), sternocleidomastoid (SCM), and suboccipital (SO) muscle tones were measured using a contact soft tissue tone measuring instrument. The statistical significance level was set to .05. Results : There were significant differences in the flexion, extension, and rotation of the cervical ROM (CROM) between the two groups (p<.05). The SCM, UT, and SO muscle tones were significantly different between the two groups (p<.05). The DNF strength and endurance showed a significant difference between the two groups (p<.05). Conclusion : We found that there were significant increases in the CROM and muscle tone and decrease in the DNF strength and endurance in the instability group. This indicated that cervical instability is affected by the DNF strength and endurance. We may recommend DNF exercises in cases of cervical instability in clinical environments.

• The Journal of Korean Physical Therapy
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• 제25권6호
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• pp.386-392
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• 2013

Purpose: This study aimed to verify the impact of the time that the sitting posture is maintained on changes in muscle performance and head alignment. Methods: The subjects of this study were healthy adults aged between 20 and 30 years. Ninety-three subjects participated in this study (male: 57, female: 36). The subjects were divided into a one-hour group, a two-hour group, and a three-hour group. All the subjects adjusted the height of their chair to a comfortable position and then seat for one, two, or over three hours. Both prior to and after the experiment, the muscle performance (muscle strength, endurance, and flexibility) of the subjects was measured. Results: In the 2-hours and 3-hour group, muscle strength, flexibility and endurance reduced significantly before and after the study, and the head alignment significantly changed. Conclusion: Thease findings showed that sitting continuously for longer than two hours decreases muscle strength, endurance, and flexibility. A flexed posture affects the muscle performance of the lumbar region and may result in problematic postures, such as a forward head position.

• Earthquakes and Structures
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• 제14권5호
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• pp.437-447
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• 2018

Computational cost is one of the major obstacles for detailed risk analysis of structures. This paper puts forward a methodology for efficient probabilistic seismic loss assessment of structures using the Endurance Time (ET) analysis and the first-order reliability method (FORM). The ET analysis efficiently yields the structural responses for a continuous range of intensities through a single response-history analysis. Taking advantage of this property of ET, FORM is employed to estimate the annual rate of exceedance for the loss components. The proposed approach is an amalgamation of two analysis approaches, ET and FORM, that significantly lower the computational costs. This makes it possible to evaluate the seismic risk of complex systems. The probability distribution of losses due to the structural and non-structural damage as well as injuries and fatalities of a prototype structure are estimated using the proposed methodology. This methodology is an alternative to the prevalent risk analysis framework of the total probability theorem. Hence, the risk estimates of the proposed approach are compared with those from the total probability theorem as a benchmark. The results indicate a satisfactory agreement between the two methods while a significantly lower computational demand for the proposed approach.

• 보건교육건강증진학회지
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• 제16권1호
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• pp.83-100
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• 1999

Modern technology has lessened the physical demand of every activities. Thus, physical inactivity has led to a rise in ‘Hypokinetic diseases’. The prefix, hypo, means lack of and kinetic refers to movement. Individuals who do not exercise regularly are at greater risk of developing hypokinetic diseases such as coronary heart disease, hypertension, hyperlipidemia, obesity, musculoskeletal disease. Systematic exercise program defenses development of hypokinetic diseases. Exercise program bases on basic physical fitness test. The physical fitness evaluation is used to degree of Wellness of the individuals. It includes the evaluation of Health-Related Physical Fitness -musclular strength, muscular endurance, flexibility, cardiorespiratory endurance, body composition - and skill or sports related fitness -agility, balance, coordination, reaction time, speed. In present study, the authors investigated health-related physical fitness test result and questionnaire for 133 male and 71 female from Jannuary 16 to March 15, 1997. The purpose of this study is to observe relationship health related physical fitness and self-perceived health status. The results are as follows. 1. There were statistically significant differences in BMI, grip strength, back strength, muscular endurance, cardiorespiratory endurance, and flexibility between male and female subjects. Flexibility is higher in female than male subject, but Others are higher in male than female subjects. 2. There were statistically significant differences in grip strength, muscular endurance between 30s, 40s, and 50s group In both gender subjects, and In cardiorespiratoryendurance between the groups especially in Female subjects. 3. For male subjects, flexibilitywas measured lower in group who classified low level in self-perceived health status than group of others. Also, for female, subjects, Muscular endurance ＆ flexibility were measured. 4. It was shown that grip strength, back strength, and muscular endurance were significantly lower in group who have chronic diseases than normal group for Male subjects. But, For female subjects, all the component were statistically insignificant results between normal and disease group. 5. Both male and female subjects, there were Positive correlation among grip strength, back strength, muscular endurance, cardiorespiratory endurance, and flexibility but, negative correlation for age. Therefore, health-related physical fitness is very important component for Heath Promotion ＆ Wellness. Physical Fitness test is valuable test in health evaluation, health management and health promotion, so available for hospital, sports center, community health center, industrial field, school etc.

• 한국항공운항학회지
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• 제23권3호
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• pp.1-7
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• 2015

In the present study, we conducted the research on the high efficiency propulsion system for the development of long-endurance UAV with an electric propulsion system. For the long endurance UAV, fair aerodynamic characteristics with the high efficiency of the propulsion system is required because the flight power and the duration time of the long-endurance UAV vary greatly depending on the efficiency of the propulsion system. Therefore, in this study, the tracking program which records the performance of motor, propeller was developed because of their wide variation in the efficiency depending on the using condition, and records from the existing flight test program were utilized to check the accuracy of the program we had developed. For the development of future long-endurance solar UAV, we confirmed the applied voltage of motor, the optimal rotation of propeller and the gear ratio of reduction gear in order to get the highest efficiency on the propulsion system at the optimal flying condition.

• 대한간호학회지
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• 제43권4호
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• pp.536-546
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• 2013

Purpose: The purpose of this study was to determine whether walking exercise improved physical function in elderly people using meta-analysis. Methods: Medical and nursing literature databases were searched to identify the studies on the effectiveness of walking exercise on physical function. In the databases, there were 16 articles reporting 21 interventions. Overall effect sizes for three outcome variables, elders' physical function in lower limb muscle endurance, whole body endurance and upper body flexibility, were calculated. Effects of study characteristics on outcome variables were analyzed. Results: The meta-analysis showed that walking exercise generally had positive effects on CST (chair stand test), 6MW (6 min walking), and SRT (standing or sitting reach test) with overall weighted effect sizes of 1.06, 0.41 and 0.29 respectively. This study also showed that the chronic disease status of the elders, intervention methods, and type of residence had different effects on CST, 6MW and SRT. Conclusion: The results indicate that walking exercise improves physical function in elders. Walking exercise which can be done at any time and any location is indeed a very effective exercise for elderly people.