• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.311-324
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• 2015

This study presents computational analyses for low-drag aerodynamic design that are applied to modify a long-endurance UAV. EAV-2 is a test-bed for a hybrid electric power system (fuel cell and solar cell) that was developed by the Korean Aerospace Research Institute (KARI) for use in future long-endurance UAVs. The computational investigation focuses on designing a wing with a reduced drag since this is the main contributor of the aerodynamic drag. The airfoil and wing aspect ratio of the least drag are defined, the fuselage configuration is modified, and raked wingtips are implemented to further reduce the profile and induced drag of EAV-2. The results indicate that the total drag was reduced by 54% relative to EAV-1, which was a small-sized version that was previously developed. In addition, static stabilities can be achieved in the longitudinal and lateral-directional by this low-drag configuration. A long-endurance flight test of 22 hours proves that the low-drag design for EAV-2 is effective and that the average power consumption is lower than the objective cruise powerof 200 Watts.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.302-309
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• 2017

The ageing of XLPE cable insulation will lead to the accelerating accumulation of space charge, which will greatly affect the safe operation of the HVDC cable. In order to investigate the influence of different ageing modes on the space charge distribution of the HVDC cable, thermal stressed, electrical stressed and electro-thermal stressed endurance tests were carried out on the XLPE peelings. The tested XLPE peelings were obtained from 160kV HVDC cable insulation. The endurance tests were carried at thermal stress of 363K, electrical stress of 20kV/mm DC and a combination of both. The Pulsed Electro-Acoustic (PEA) method was used to measure the space charge distribution of the samples. The influences of ageing on the trap energy distribution were analyzed based on the isothermal relaxation theory and the decay characteristics of the space charge. The results showed that thermal ageing would help to improve the crystalline morphologies of the XLPE at the early stage. The total amount of space charge decreased compared to the ones before thermal ageing. The long term of electrical stress would result in the cleavage of polymer molecule chains which would intensify the accumulation of space charge and increase the density and depth of electron traps. With a combination of electrical and thermal stress, the injection and migration of space charge were more significant. Besides, the depth and density of electron traps increased rapidly with the increase of endurance time.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.225-231
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• 2016

A military vehicle is driven at different usage modes with the army application and servicing conditions. For practical durability validation, DT(Development Test) on a new military vehicle should be run up to the durability target kilometers on test courses in the specified proving ground. Driving velocities with test courses at the endurance mode of DT are established definitely. However, OT(Operational Test) and initial endurance test of production car can't be performed only in the DT courses due to the development period limit. Therefore, this paper focuses on the method to analyze the relative road damages between the endurance test in DT and other endurance test. Road load acquisition tests on KLTV(Korean Light Tactical Vehicle) were implemented at 15 driving modes in off-road and cross-country courses of two tests. Wheel accelerations were processed through band-pass filter, and then the main frequency and maximum power of the signals were computed by PSD analysis. Finally, using the proving ground optimization based on RDS(Relative Damage Spectrum) characterization, the damage factors between off-roads of test courses were determined.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.4
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• pp.1-8
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• 2019

PURPOSE: The purpose of this study was to compare the maximum knee strength and endurance of elderly Korean women with Kellgren-Lawrence grade (K-L II) by age. METHODS: In this study, the total number of participants was 50, divided into five groups of 10 by age. Maximum knee muscle strength was measured at a low speed of 60°/sec using Biodex, an isokinetic device for comparison of maximum knee muscle strength, whereas muscle endurance was measured by muscle contraction at a high speed of 180°/sec. The peak torque values of the extensor and flexor muscles in the muscle strength and muscle endurance tests were collected according to each classification. RESULTS: The results of the experiment show that maximum muscle strength and muscle endurance decreased significantly at 60°/sec and 180°/sec during flexion and extension according to age (p<.05). In particular, the age group of 71 to 75 years showed the most significant correlation with other age groups (p<.05). CONCLUSION: The results of this study can be used as basic data for increasing physical activity and muscle strength in women with knee osteoarthritis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.147-155
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• 2017

A new endurance test-pattern generation on NAND-flash memory is proposed to improve test cost. We mainly focus on the correlation between the data-pattern and the device error-rate during endurance testing. The novelty is the development of testing method using quasi-random pattern based on device architectures in order to increase the test efficiency during time-consuming endurance testing. It has been proven by the experiments using the commercial 32 nm NAND flash-memory. Using the proposed method, the error-rate increases up to 18.6% compared to that of the conventional method which uses pseudo-random pattern. Endurance testing time using the proposed quasi-random pattern is faster than that of using the conventional pseudo-random pattern since it is possible to reach the target error rate quickly using the proposed one. Accordingly, the proposed method provides more low-cost testing solutions compared to the previous pseudo-random testing patterns.

• Journal of East-West Nursing Research
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• v.17 no.1
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• pp.24-30
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• 2011

Purpose: This study was to examine the effects of Dan Jeon Breathing on physical endurance, cognitive function, and depression in middle-aged women. Methods: This study employed a quasi-experimental with a nonequivalent control group pre-post test design. Participants were 59 middle-aged women and randomly assigned to the experimental or control group. Dan Jeon Breathing was carried out for 40 minutes per day, 3 times per week for 12 weeks between March 1 and July 31, 2010. Data were analyzed by Mann-Whitney U test and Wilcoxon signed ranked test for paired data. Results: After Dan Jeon Breathing intervention, the scores of physical endurance and depression of the experimental group were significantly higher than those of the control group. However, the scores of cognitive function between two groups were not significantly different. Conclusion: The Dan Jeon Breathing can be utilized as a nursing intervention for physical endurance and depression in middle-aged women. Also, a revised model of Dan Jeon Breathing is needed to be examined for cognitive function.

• Biomedical Science Letters
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• v.11 no.2
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• pp.227-235
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• 2005

It has been reported that endurance performance is influenced by various environmental and genetic factors. In view of an important role of human mitochondrial DNA (mtDNA) as a candidate for endurance performance, this study focused on the relationships between $VO_{2max}$ value as a measure of endurance performance or other associated phenotypes and four mtDNA restriction fragment length polymorphisms (RFLPs) (Bam HI, Hinc II1, Hinc II2 and Nci I) in the NADH dehydrogenase subunit 5 and one (Kpn I) in the D-loop region of mtDNA. MtDNA was purified from buffy coat in human peripheral blood, and PCR-RFLP analysis was performed to estimate the allele frequencies of each polymorphism in the mtDNA. There were no significant differences in allele distributions of all polymorphisms studied between male athletes and controls, respectively (P>0.05). However, the Kpn I polymorphism was significantly associated with diastolic blood pressure level in male athletes, respectively (P<0.05). Therefore, our results suggest that this polymorphism might be one of the factors modifying inter-individual difference in cardiovascular risk. Further studies using larger sample size will be required to generalize these results from the study described herein.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.804-807
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• 2008

Recently, with the increase of high rise and huge scale building construction, the use of high strength concrete has been increasing. High strength concrete has dense pore structure, which is susceptible to be damaged due to fire attack. For this, many researchers provide proper fire endurance method. In this paper, to provide the priority for selecting fire endurance method in high strength concrete execution, AHP technique is applied based on expert questionnaire. Fire endurance performance efficiency and ordinary performance efficiency was selected for level 1. Fire endurance performance efficiency had larger weight than ordinary one.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.104-108
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• 2012

All of the Korean high speed train windows have been imported from abroad up to now. In this paper, the air pressure endurance test device for high speed train windows was studied and developed. This test device can create air pressure variation similar to train running real condition and carry out pressure endurance test according to international standard. Henceforward, this test device will be useful for domestic production of high speed train windows.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.2 no.1
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• pp.83-92
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• 2004

This study aims to the influenced factor analysis of spinal cord independence measure(SCIM), on walking velocity, walking endurance, time up & go(TUG), and subject characteristics. The subject of this study were 12 persons with incomplete spinal cord injury(ASIA C, D). All subject ambulatory with or without an assistive device. All participants were assessed on SCIM(score), walking velocity(m/s), walking endurance(m) and TUG(s). The data were analyzed using independent t-test and stepwise multiple regression. The results revealed that no statistical difference was noted in subject characteristics among SCIM, walking velocity, walking endurance, TUG(p>0.5). The independence score, breathing-sphincter control and ambulation were important factors in TUG(31.4%). The results suggest that SCIM may be an inappropriate assessment tool to predict gait ability of patient with incomplete spinal cord injury. Further study about gait speed, gait endurance and TUG by change of SCIM is needed using to patient of incomplete spinal cord injury.