• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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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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• 제12권1호
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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.

• 한국자동차공학회논문집
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• 제24권2호
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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.

• 대한물리의학회지
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• 제14권4호
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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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• 제17권1호
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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.

• 동서간호학연구지
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• 제17권1호
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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.

• 대한의생명과학회지
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• 제11권2호
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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.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.804-807
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• 2008

최근 건축 구조물의 초고층화 대형화로 인해 고강도화 되는 콘크리트는 치밀한 조직으로 인해 화재시 폭렬에 취약하고, 내화성이 저하되는 문제점을 지니고 있다. 이로 인해 국내에서도 내화의 문제점을 인식하고 방안제도를 마련하고 있으며, 많은 연구진에 의해 고강도 콘크리트의 내화공법이 소개되고 있다. 이에 본 연구에서는 고강도 콘크리트의 내화공법 선정시 중요도를 관련 전문가의 설문조사를 기반으로 AHP 기법을 이용하여 분석하였다. 설문조사를 통한 분석 결과 상위 평가항목의 화재성능과 상시성능 중 내화공법 선정시에는 화재성능이 가장 중요시되는 것으로 나타났다. 화재성능에 대한 하위 항목에서는 인명보호가 중요한 요소로 산정되었고, 인명보호에 대한 하위 항목에서의 설문분석 결과 유해가스 발생억제가 중요한 요소로 산정되었다.

• 한국철도학회논문집
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• 제15권2호
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• pp.104-108
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• 2012

현재까지 국내에서 운행되고 있는 고속철도차량용 창문은 전량 해외 제품의 수입에 의존하고 있다. 본 연구에서는 고속철도차량의 주행도중에 발생되는 공기 압력 변동 값을 반복적으로 생성시킬 수 있고 국제적으로 통용되는 규격에 부합하는 압력 내구성 시험을 수행할 수 있는 시험기의 개발에 대한 연구를 수행하였다. 따라서 향후 고속철도차량용 창문유리에 대한 압력 내구성시험기의 연구개발을 통하여 창유리의 국산화에 기여할 수 있을 것으로 사료된다.

• 대한임상전기생리학회지
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• 제2권1호
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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.