• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.47-53
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• 2010

A performance test of a 75 ton class turbopump inter propellant seal is conducted using water to evaluate leakage and endurance performance. Each fuel pump side part and oxidizer pump side part of a prototype inter propellant seal has been tested for verifying endurance performance during total accumulated test time 2,100 sec in water. The fuel pump side part with 1 stage carbon floating ring seal shows average leakage rate 13.7 gram/sec under average seal differential pressure 9.4 bar. On the other hand, the LOx pump side part with 2 stage carbon floating ring seal shows average leakage rate 7.3 gram/sec under average seal differential pressure 9.5 bar. After the endurance performance test, the inter propellant seal shows good physical condition. A cryogenic leakage performance test of the inter propellant seal will be performed using LN2 in the near future.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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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 muscle and joint health
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• v.19 no.1
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• pp.16-26
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• 2012

Purpose: The purpose of this study was to investigate the effects of lumbar stabilization exercise on balance ability in patients with adolescent idiopathic scoliosis. Methods: This study was one group pretest-posttest design. Twenty young idiopathic scoliosis patients were recruited for this study. They had the lumbar stabilization exercise program for 40 minutes a day, three times per week for 3 weeks. The lumbar trunk muscle endurance test and clinical balance tests (functional forward reach, functional lateral reach, Fukuda 50-stepping, one leg standing with eyes open and eyes closed) were measured before and after the lumbar stabilization exercise. Results: There were significant differences between pre-and post-test in absolute value of the difference between right and left lateral reach, distance of Fukud 50-stepping and one leg standing on the each side with eyes closed(p<.05). The results showed that the lumbar trunk muscle endurance significantly increased(p<.05). Conclusion: In this study indicated that the lumbar stabilization exercise was effective on balance ability and lumbar trunk muscle endurance in patients with young idiopathic scoliosis.

• Tribology and Lubricants
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• v.21 no.6
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• pp.278-282
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• 2005

Deep groove ball bearing is installed in a control element of an integral nuclear reactor, where water is used as coolant and lubricant. This bearing is made of STS440C stainless steel for the raceways and the balls to use in radioactive environment and water. It is known that the retainer design affects ball bearing operability and endurance life, however there is no verified retainer design and material for water lubricated ball bearing. Four kinds of retainers are manufactured for the endurance test of water lubricated deep groove ball bearing. Three of them are commercially developed types and the other is designed for this research. It is verified that ball bearings with steel pressed and general plastic retainer can not survive to required life in the water, however bearings with machined type and cylinder type retainer can survive. This proves that one of the major design parameters for water lubricated ball bearing is retainer type and material. In this paper, experimental research of endurance test for water-lubricated ball bearing are reported.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.3
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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.

• Physical Therapy Korea
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• v.10 no.2
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• pp.1-10
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• 2003

This study was carried out to help the comprehensive rehabilitation of spinal cord injuries by measuring propulsion force and endurance exerted on wheelchair handrims, and predicting the differences among three different rear axle positions. The BTE (Baltimore Therapeutic Exerciser) work simulator was used on 9 paraplegia to test the force and endurance during wheelchair propulsion. The 141 large wheel of the BTE work simulator and a standard wheelchair with removed handrims were used for simulating wheelchair propulsion. The neurological and demographical characteristics of the patients were collected by personal interviews and direct examinations. The Kruskal-Wallis test was used to compare force and endurance among the groups. The strongest maximum isometric strength was produced when the rear axle of the wheelchair and the acromion process were on the same coronal plane. Although there were no significant differences statistically, moving the rear axle forward did result in greater isotonic strength. The research suggests that better functional activity of persons with paraplegia is possible when the rear axle of the wheelchair is appropriately adjusted.

• Journal of Korean Academy of Nursing
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• v.43 no.4
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.553-556
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• 2004

This paper is to investigate the spalling and fire endurance of high performance RC column member with PP fiber and lateral confinement of metal lath and non fire resistance removal type form. According to test results, combination of PP fiber and metal lath as well as use fire resistance non removal type form had favorable fire resistance by discharging internal vapour pressure and lateral confining. After fire endurance test, compressive strength decreased markedly caused by internal expansion pressure and crack. Residual strength of plain concrete was decreased to $22\%$. The use of PP fiber and lateral confinement of metal lath and non removal type form enhanced the residual strength above $40\%$. Especially, the combination of $0.1\%$ of PP fiber and lateral confinement with the level of 2.3T exhibited more than $51\%$ of residual strength. Therefore, to improve fire endurance and spalling resistance, the combination of $0.1\%$ of PP fiber and metal lath with 2.3T can be the proper measure.

• Journal of the Korean Graphic Arts Communication Society
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• v.30 no.3
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• pp.57-64
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• 2012

When papers each made with sea-algae pulp 1%, 5% and soft, hard wood pulp were aged for 12days. Paper made with soft wood pulp is 30% loss of folding endurance, made with hard wood pulp is 50% loss of folding endurance. On the other, papers each made with 9% sea-algae pulp and soft, hard wood pulp were 18% loss of folding endurance. In the aging test of paper made with different freeness paper made with 300ml CSF, is more effective than 400ml CSF, 500ml CSF.

• Journal of the Korean Society for Railway
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• v.14 no.5
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• pp.391-397
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• 2011

In this paper, the pressure endurance test of passenger train's glass window which was developed for next high speed train was studied. At first, pressure test equipment which will be able to generate the maximum pressure same as crossing case between two trainsets in the tunnel was developed. Afterwards the pressure test and evaluation that are based on NFF31-314 were carried out and studied.