• Physical Therapy Rehabilitation Science
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• v.10 no.2
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• pp.156-160
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• 2021

Objective: Low back pain easily becomes chronic and has a high recurrence rate. Therefore, it is most important to prevent chronicity and reduce the risk of recurrence in the early stages of back pain or at the stage with mild pain. Therefore, this study was conducted to compare hip joint muscle strength, trunk muscle endurance, and pelvic alignment between subjects with mild low back pain and subjects without back pain. Design: Crossed-sectional study Methods: The study was conducted by recruiting 30 students in their twenties who are enrolled in K University in Gyeongsangnam-do, and classifying them into 15 patients with mild back pain and 15 patients with normal. The subjects who participated in the experiment were measured for hip flexor and extensor muscle strength, trunk flexion and extension muscle endurance, and pelvic alignment. To measure hip joint muscle strength, biodex was used, and muscle endurance of the trunk was recorded at the end range of the trunk flexion and extension. And pelvic alignment was measured using Formetric 4D. Results: There were no significant differences in hip joint muscle strength, pelvic alignment, and trunk extension muscle endurance. The retention time was found to be significantly shorter in the mild low back pain group than in the normal group for trunk flexion muscle endurance. Conclusions: In the early stages of back pain or in the mild pain stage, training to increase muscle endurance of the flexor muscles may be helpful.

• 한국체육학회지인문사회과학편
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• v.55 no.6
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• pp.691-700
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• 2016

The purpose of this study was to investigate the effects of long-term endurance exercise or resistance exercise training on muscle anabolic/catabolic pathway. 50wks-old male Wistar rats(n=30) were randomly assigned for 3 groups (sedentary, endurance exercise, resistance exercise group). After 12-week of training, plantaris muscles were dissect to measure protein level. Akt/mTOR signal-related proteins were significantly increased only after resistance exercise training, but catabolic signal-related proteins, FoxO1 and MuRF1, were significantly decreased after resistance and endurance exercise training. After endurance exercise training, AMPK and PGC-1α protein levels were significantly increased. Therefore, the endurance exercise training has been shown to affect the protein balance of aging muscle through inhibition of muscle protein catabolism. The present results suggest the possibility that not only resistance exercise but also endurance exercise will be affectable to keep or increase muscle volume and capacity of middle-aged people.

• Korean Journal of Exercise Nutrition
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• v.16 no.1
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• pp.51-59
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• 2012

The purpose of this study was to examine the effects of endurance training and prolonged L-arginine supplementation on blood glucose, blood insulin, muscle glycogen, muscle glycogen synthase (GS), muscle nitric oxide (NO), muscle nitric oxide synthase (NOS), endurance performance. We equally divided 36 Sprague-Dawley mice to be distributed into control group, L-NMMA treated group and L-arginine treated group. The L-arginine treated group and L-NMMA treated group consumed 10 mg/kg/day of L-arginine and 5 mg/kg/day of L-NMMA for 6 weeks period. Mice of control group, L-arginine treated group, and L-NMMA treated groups performed swimming exercise training for 60 min once a day, 5 days per week for 6 weeks. Blood glucose had tendency to increase in L-arginine treated group than the control group, and insulin significantly increased in L-arginine treated group than the control group. L-arginine treated group showed significant increase in glycogen, GS, NO and NOS in the gastrocnemius muscle and soleus muscle compared to the control group. Whereas L-NMMA treated group showed the lowest glycogen, GS, NO and NOS in the gastrocnemius muscle and soleus muscle compared to control group and L-arginine treated group. Exhaustive swimming time had tendency to increase in L-arginine treated group compared to the value for control group. These reults indicate that endurance training and prolonged L-arginine supplementation appear to be effective in exhancing nitric oxide production, glycogen concentration and endurance performance.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.374-382
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• 2014

This paper presents the computational aerodynamic analysis of a long-endurance UAV that was developed by the Korea Aerospace Research Institute (KARI), named EAV-2. EAV-2 is a technical demonstrator of aerodynamically efficient design, as well as a hybrid electric-propulsion system for future long-endurance UAVs. We evaluated the aerodynamic characteristics of six low-Reynolds number airfoils, using a panel method code, XFOIL, to select an optimal airfoil for the long-endurance mission of EAV-2. The computational results by a CFD code, FLUENT, suggested that the aerodynamic performance of EAV-2 would be notably improved after adopting SG6043 airfoil, and modifying the fuselage design. This reduced the total drag by 43%, compared to that of a previous KARI model, EAV-1, at the target lift of $C_L=1.0$. Also, we achieved a drag reduction of approximately 14% by means of the low-drag fuselage configuration.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.160-164
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• 2007

An automotive wheel bearing is one of the most important components to guarantee the service life of a passenger car. The endurance life of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions, temperature, loading conditions, bearing geometry, internal clearance and so on. Generally, a tapered roller bearing gives longer endurance life than that of an equivalent size ball bearing. Consequently, the application of taper bearing units will be increased for more compact design and extended warranty. In this paper, we derive the relation between loads and deformations of a taper bearing unit. On the basis of that, we calculate the endurance life of the taper bearing unit considering initial axial clearance.

• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.111-117
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• 2016

A new configuration of tiltrotor UAV previously suggested by Korea Aerospace Research Institute (KARI) for the purpose of increasing the endurance performance in airplane mode flight has extended wings attached to the nacelle and rotated with the nacelle according to the flight modes. In this research, the effectiveness of the extended wing on the enhancement of the endurance performance of KARI tiltrotor UAV (TR60) was analytically investigated based on CFD analysis results. Flight tests and ground tests of measuring the fuel consumption were also conducted to directly compare the endurance performance for the two configurations of TR60 baseline and TR60 extended-wing model.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.1-5
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• 2011

In order to evaluate fatigue endurance for an ultra-light weight inline skate frame, FEM analysis was performed. Tensile properties and a S-N curve were determined through tensile and fatigue tests on a modified Al-7075+$S_c$ alloy. The yield and ultimate tensile strengths were 553.3 MPa and 705.5 MPa, respectively. The fatigue endurance limit of this alloy was 201.2 MPa. For evaluating the fatigue endurance of the inline skate frame, the S-N data were compared with the stress analysis results through FEM analysis of the frame. The maximum Von-Mises stress of the frame was determined 106 MPa through FEM analysis of the frame, assuming that the rider weight is 75 Kg. Conclusively, on the basis of fatigue limit, the inline skate frame has a safety factor of approximately 2.0.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.256-261
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• 2014

Endurance test procedures of multipurpose tactical vehicle is constructed by comparing the Korea defence standard and TOP-2-2-506. The plan was to make the best reflect the operational environment and the actual production purposes. Endurance test of multipurpose tactical vehicle more stringent than the existing other military vehicles validation procedures. But the test plan, it is possible to reduce the cost and schedule of long verification that occurs because of the Endurance test. Through a comparison of the dynamic characteristic analysis, change of test center was to ensure the reliability and validity.

• Phonetics and Speech Sciences
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• v.6 no.2
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• pp.97-106
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• 2014

The purpose of this study was to (1) establish a Korean adult normative data for Iowa Oral Performance Instrument, (2) investigate the characteristics of maximal tongue and lip strength and tongue endurance scores according to age and gender, and (3) examine the correlation of those scores. The results showed that there were no significant differences of gender in maximal tongue strength and tongue endurance scores. But there were significant differences of age in maximal tongue and lip strength and tongue endurance scores. The data will provide an important database for speech language pathology with the purpose of diagnosis and treatment of tongue and lip dysfunction.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.61-73
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• 2007

The purpose of this study was to investigate the influence of the muscular endurance on the kinematic factors during a prolonged run. Subjects, 12 males, who were divided into three groups(lower group, general group, and in higher group) after measuring the lower limb's muscular endurance previously. They were asked toe run on the treadmill at 7.4km/h of speed. To analyze the kinematics parameters of the trunk during running, the ProReflex MCU Camera(Qualisys, Sweden) were used. All parameters were sampled from 5 minute, 40 minute, and 60 minute moments during running. An ANOVA with Repeated Measure was used to test the statistic significance between and within groups for all parameters determined with SPSS 11.0. Significance was defined as p<.05. The conclusions were as follows; There was significantly difference within(lapse of running time) groups in the take-off and minimum knee angle event of swing phase of the trunk flexion and extension. In conclusion, the muscular endurance affected on movement of the trunk during a prolonged run. In addition, it showed that there was significant difference in the energy consumption by lapse of running time. Therefore, it seems to be relationships between the muscular endurance and running efficiency.