• The Journal of Korean Physical Therapy
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• 제23권3호
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• pp.57-63
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• 2011

Purpose: The purposes of this study were to investigate the effectiveness of Pilates exercise on Fitness Factors related to motor performance including flexibility, agility, power, balance, and muscle endurance. Methods: Forty subjects were randomly allocated to one of two groups. The Pilates group did Pilates exercises 3 times a week for 8weeks, 60 minutes each time, and submitted to evaluation of protocols to assess sitting and reaching tests, a standing broad jump test, a side step test, a balance test using a Biodex Stability System, and muscle endurance using CSMI. Results: The Pilates group (n=20) participated in Pilates exercises three times in a week for eight weeks. The results show significant post-test differences in the Pilates group in the following areas: flexibility, agility, power, balance and muscle endurance. There was no significant increase in the control group. Post-exercise, there was no significant difference between the Pilates and control group. Conclusion: The Pilates method can offer significant improvement in personal flexibility, agility, power, balance, and muscle endurance. This study suggests that individuals can improve their Fitness Factors related to motor performance using Pilates exercises that do not require equipment or a high degree of skill. Further study is required to quantify the benefits of Pilates exercise.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.239-249
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• 2018

Physical tests are performed at various stages of the development cycle of a product, from prototype validation to product qualification. Although costly, there are growing demands for qualification tests like endurance vibration testing to be more representative of the real world. At the same time there are growing demands to assess the durability of these items based on FEA simulation. In this paper, we will explain how to set up a CAE-based test and how to correlate the results with some physical measurements. Specific assumptions will be explained and some advantages of using virtual tests will be highlighted such as the reduction of the number of prototypes needed, investigations on failures, evaluation of the level of reliability via sensitivity analysis, evaluation of the margins are at the end of a successful test. This presentation will therefore focus on explaining and showing how virtual tests can enrich the exploitation of physical tests.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2181-2186
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• 2014

Generally, the motor inside vehicle is exposed to highly ambient temperature and large vibration according to repeatedly starting and stopping for very short time. So, in this paper, the rotor shape design was performed to improve demagnetization endurance by considering the starting current of the Brushless DC (BLDC) Motor through the Finite Element Method(FEM). As a result, the partial irreversible demagnetization was occurred by starting current at the end of Permanent Magnets of the basic model. To solve this problem, the flux barrier design was performed and the flux on the rotor core was limited. Accordingly, demagnetization endurance and operating characteristics were improved.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1998년도 추계학술발표회 논문 초록집
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• pp.73-76
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• 1998

To use glazing systems protected by automatic sprinklers as fire barriers in building compartmentation, fire endurance tests of these systems have been performed by several research workers. Most of the tests concerned the types of glasses and sprinklers, sprinkler water flow rate, and sprinkler activation time. Horizontal side wall sprinklers and window glazing systems with a vertical center mullion were mainly applied in the tests. In the study, full-scale fire endurance tests were carried out to verify the ability of large glazing systems divided by a horizontal mullion and protected by pendent vertical sprinklers. The result shows that the protrusive length of the horizontal mullion, which is perpendicular to the glass surface, is the main parameter that determines the fire resistance rating of the systems. The mullion obstructs the water flow in the glass.

• The Journal of Korean Physical Therapy
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• 제28권3호
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• pp.183-188
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• 2016

Purpose: The aim of the study was to investigate neck posture, range of motion, muscle endurance and self-report of pain and disability in smartphone users. Methods: Seventy-eight university student volunteers, aged between 18 and 30 years (mean age 23.2), were assessed for: a head-neck posture by measuring cranial vertical angle, neck range of motions using cervical range of motion device, and a deep neck flexor endurance using a stabilizer. Finally, subjects were asked about their neck pain and completed disability questionnaires, ie, Short Form McGill Pain Questionnaire, Neck Disability Index, and World Health Organization Disability Assessment Schedule 2.0. Results: Thirty-eight subjects experienced recurrent neck pain with/without upper limb pain (neck pain group) and 40 reported no current neck pain with/without upper limb pain (no neck pain group). Differences were found between groups on pain and disability questionnaires. Subjects with neck pain had significantly higher disability scores than those of no neck pain group. However, there were no differences observed between groups in a head-neck posture, neck range of motions, and deep neck muscle endurance time. The smartphone usage time was negatively correlated with neck pain intensity and disability score whereas it had positive relationship with flexibility and posture. Conclusion: Group differences were observed as lower capacity not only for neck specific daily activities but for general functioning in daily routine when the neck pain and no neck pain groups were compared. Therefore, functioning in daily activities should be investigated as prevention for further developing neck pain in smartphone users.

• 대한임상전기생리학회지
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• 제3권1호
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• pp.49-59
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• 2005

This study assigns each 8 of 24 normal persons to control group(Group I), strength increase group(Group II) and endurance increase group(Group III) to analyze differences in changes of strength and endurance with surface electromyography and kinetics according to application modes of neuromuscular electrical stimulation(NMES). Group I had not any treatment, group II performed 15 repeated contraction with 60% intensity of maximal voluntary isometric contraction(MVIC) by setting 10-sec on time and 50-sec off time and group III conducted 30 repeated contraction with 30% intensity of MVIC by setting 10-sec on time and 20-sec off time. For neuromuscular electrical stimulation, 2,500 Hz of Russian current, 35 pps of pulse rate and 200 of pulse width. Neuromuscular electrical stimulation was conducted by five times for total 4 weeks. Before and after experimentmotor unit action potential of vastus medialis, rectus femoris and vastus lateralis were measured with sEMG, median frequency(MDF) was analyzed, and thus the following results were obtained. There was significant difference in the period of measuring vastus medialis and rectus femoris in change of MDF and interaction among groups with analysis of surface electromyography before and after neuromuscular electrical stimulation(p<.001) and in particular, there was a remarkable change among groups according to the period of measurement. In conclusion, NMES influenced changes of strength and endurance according to its application modes and in particular, it was found that strength increment application had a significant influence on strength increment in applying short-time NMES.

• 한국수소및신에너지학회논문집
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• 제25권4호
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• pp.393-404
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• 2014

Unmanned aerial vehicles (UAVs) have been applied to not only military missions like surveillance and reconnaissance but also commercial missions like meteorological observation, aerial photograph, communication relay, internet network build and disaster observation. Fuel cells make UAVs eco-friendly by using hydrogen. Proton exchange membrane fuel cells (PEMFCs) show low operation temperature, high efficiency, low noise and high energy density and those characterisitcs are well fitted with UAVs. Thus Fuel cell based UAVs have been actively developed in the world. Recently, fuel cell UAVs have started to develope for high altitude UAVs because target altitude of UAVs is expanded upto stratosphere altitude. Long endurance of UAVs is essential to improve effects of the missions. Improvement of UAV endurance time could be fulfilled by developing a hydrogen fuel storage system with high energy density and reducing the weight of UAVs. In this paper, research trend and analysis of fuel cell UAVs are introduced in terms of their altitude and endurance time and then the prospect of fuel cell UAVs are shown.

• 한국콘텐츠학회논문지
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• 제11권12호
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• pp.326-334
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• 2011

본 연구의 목적은 깊은 목굽힘근과 깊은 목폄근의 두께를 목근육 지구력 검사 동안 측정하여 목통증 경험 유무에 따라 깊은 목근육들의 크기에 차이가 있는 지 관찰하였다. 컴퓨터 사용이 많은 대학생 65명이 참여하였으며, 목통증이나 두통으로 인하여 일상생활을 수행하는데 제약이 없고 현재 척추증상이 없는 자를 대상으로 하였다. 근육의 두께는 근지구력검사를 수행하는 중 근이완기, 수축기와 제한시점에서 각각 측정하였다. 목통증과 기능제한에 대한 정보는 설문지를 통하여 수집하였다. 목통증 경험이 없는 대상자들 (그룹1)의 근지구력 시간이 목통증 경험이 있는 대상자들(그룹2)보다 통계적으로 유의하게 길었다 (p<0.01). 그룹1 대상자의 왼쪽 긴목근이 그룹2 대상자보다 근이완기에서 두껍게 관찰되었으며(p=0.02), 오른쪽 긴머리근은 목통증 경험이 없는 대상자들이 근수축에서 제한시점까지의 변화가 목통증 경험이 있는 대상자보다 크게 관찰되었다(p=<0.01). 목통증과 연관하여 특정 근육의 기능파악이 중요하며, 임상 대상자들의 목수축 패턴과 근기능에 대한 연구가 더 필요하다.

• 한국산학기술학회논문지
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• 제15권2호
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• pp.815-827
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• 2014

본 연구는 복근의 정적 지구력 평가 도구로서의 등척성 버티기 방법의 타당성을 검증하고 최적의 적용 각도를 결정해내기 위해 수행되었다. 92명(남 68명, 여 24명)의 피험자가 자발적으로 실험에 참여하여 다음과 같은 결과를 얻었다. 유산소 역량과 근지구력 역량 사이의 상관성은 남성에서보다 여성에게서 더 높게 나타났으며 등척성 버티기의 수행 시간과 윗몸일으키기의 반복 횟수 사이에 정적인 상관관계를 나타냈다. 또한 40도의 경사도를 적용 시 30도 및 50도와 비교해 근지구력과의 가장 높은 상관성을 나타냈다. 이와 같은 결과를 통해 복근지구력의 평가 도구로서의 등척성 버티기 방법이 요부의 잠재적 상해 위험을 지닌 것으로 보고되고 있는 윗몸일으키기 방법을 대체할 수 있는 대안으로 사용될 수 있으며 적용 시 40도의 각도를 적용하는 것이 적절하다는 결론을 내릴 수 있었다. 서로 다른 연령 및 체력 상태에 따른 최적의 적용 각도에 대해서는 후속 연구를 통해 밝혀져야 할 것이다.

• 항공우주시스템공학회지
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• 제15권4호
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• pp.11-20
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• 2021

The estimation of hovering flight time of multicopters using the battery power propulsion system is important for the development and design of the aircraft and its operation. For a given operational weight, the maximum possible battery weight can be decided using both a conventional energy density method and a new Peukert law. In the present study, the hovering flight time is predicted using both methods. The specific data of multicopters in the published literatures were employed for the computation of the hovering flight time. The results were validated with the measured data. The effect of figure of merit of propeller, battery discharging process on the hovering flight time was evaluated, Finally, the effect of the battery cell and package connection types on the hovering time was investigated. It was found that the combination of serial battery cell connections and parallel package connection is the bast in the endurance maximization aspect. As the cell number increases in a package, the hovering flight time is increased. There exists the max. battery ratio for the given takeoff gross weight.