• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.557-560
• /
• 2004

This paper is to investigate the fire endurance of high performance concrete with the contents of cellulose fiber. According to test results, the use of CL lead to decrease in fluidity. For compressive strength, the use of CL had no influence on compressive strength. For spalling properties, plain concrete showed a severe spalling failure. The use of CL protected from spalling of concrete, but most specimens had scale failure and partial destruction of specimens. This is due to the insufficient fiber length and diameter of CL fiber, which was unable to discharging the internal vapour pressure. For this reason, CL fiber can not be used to protect from spalling oh high performance concrete. Residual strength was observed to $5\~7\%$ of original strength.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.245-246
• /
• 2023

The unit curtain wall is an exterior finish currently used on the exterior walls of high-rise buildings. Curtain walls used as non-endurance walls are largely classified into stick curtain walls and unit curtain walls, and their use has recently been on the rise to reduce risks at construction sites through factory manufacturing. Accordingly, this study attempted to examine the insulation performance according to the shape of the unit curtain wall profile through insulation simulation.

• Fire Science and Engineering
• /
• v.34 no.2
• /
• pp.97-102
• /
• 2020

The purpose of this study was to investigate the effectiveness of a Tabata exercise program as an alternative for firefighters whose working environment makes it difficult to manage physical fitness. The Tabata exercise program, in which 16 people participated, led to increased muscle mass and reduced weight and body fat, which not only improved the health of the firefighters but also improved their cardiopulmonary endurance, muscle endurance, and muscle strength, which are essential elements during firefighting emergency relief activities. On the basis of these results, it is believed that developing and providing guidelines for scientific and systematic exercise programs to firefighters will lead to better work capability during fire and disaster situations.

• Journal of Korean Academy of Nursing
• /
• v.16 no.1
• /
• pp.55-66
• /
• 1986

The effect on strength and endurance training (SET) (2 patients) were compared with those of strength training(ST) (2 patients) in patients with-chronic obstructive pulmonary disease. The result of training was assessed by 4 tests: maximal inspiratory pressure(PImax), sustainable inspiratory pressure (SIP), maximal voluntary ventiiation(MVV) and bronchitis-emphysema symptom checklist(BESC). Measurements were repeated before and after training per week for 6 weeks. The SET group performed inspiratory muscle training, using a inspiratory muscle trainer 30 minutes per day, 6 days per week and performing endurance training-12-minute walking-2 days per week for 6 weeks, whereas the ST-only group trained for 30 minutes daily, 6 days per week using inspiratory muscle trainer. SET was no significant increase in exercise performance, whereas ST produced an increase in SIP and a decrease in BESC. There was significant change in BESC betweet the two groups. A simple at home training program using inspiartory muscle trainer was more effective than that of SET program in improving exercise performance of some patients with COPD.h COPD.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.4
• /
• pp.524-530
• /
• 2002

Micro electric spark discharge device was fabricated on a FOTURAN glass wafer using MEMS processing technique and its performance of electron discharge and subsequent formation of ignition kernel were tested. Micro electric spark device is an essential subsystem of a power MEMS that has been under development in this laboratories. In a combustion chamber of sub millimeter scale depth, spark electrodes are formed by electroplating Ni on a base plate of FOTURAN glass wafer. Optimization of spark voltage and spark gap is crucial for stable ignition and endurance of the electrodes. Namely, wider spark gaps insures stable ignition but requires higher ignition voltage to overcome the spark barrier. Also, electron discharge across larger voltage tends to erode the electrodes limiting the endurance of the overall system. In the present study, the discharge characteristics of the proptotype ignition device was measured in terms of electric quantities such as voltage and currant with spark gap and end shape as parameters. Discharge voltage shows a little decrease in width of less than 50㎛ and increases with electrode gap size. Reliability test shows no severe damage over 10$\^$6/ times of discharge test resulting in satisfactory performance for application to proposed power MEMS devices.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.104-109
• /
• 2018

Generally, the durability of the parking lock gear is evaluated through an endurance test for the entire transmission but no test standard exists for the durability test of one part of a parking lock gear. Therefore, in this study, the durability test standards of the parking lock gear were determined autonomously, and the durability performance test was conducted. A static fracture test was carried out to determine the yield strength of the parking lock gear, and a durability test condition was set to 60 % of the yield strength. The durability test of 1,000,000 times was conducted under the given conditions using a dedicated test jig manufactured for the test. Because the jig fractured during the static fracture test, finite element analysis for the jig was carried out and the jig was re-designed. The modified jig was manufactured and the durability test was carried out based on the test standard of autonomously. The basic data on the performance and endurance limit of the parking lock gear were obtained using these tests and analyses, and the basic data will be used as fundamental materials for the design and the development of the parking lock gear.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.427-427
• /
• 2012

Ferroelectric-gate field effect transistor based memory using a nanowire as a conducting channel offers exceptional advantages over conventional memory devices, like small cell size, low-voltage operation, low power consumption, fast programming/erase speed and non-volatility. We successfully fabricated ferroelectric nonvolatile memory devices using both n-type and p-type Si nanowires coated with organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] via a low temperature fabrication process. The devices performance was carefully characterized in terms of their electrical transport, retention time and endurance test. Our p-type Si NW ferroelectric memory devices exhibit excellent memory characteristics with a large modulation in channel conductance between ON and OFF states exceeding $10^5$; long retention time of over $5{\times}10^4$ sec and high endurance of over 105 programming cycles while maintaining ON/OFF ratio higher $10^3$. This result offers a viable way to fabricate a high performance high-density nonvolatile memory device using a low temperature fabrication processing technique, which makes it suitable for flexible electronics.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.5
• /
• pp.413-422
• /
• 2012

The ducted fan for a small UAV propulsion can reconnoiter and observe in a town and a small area, it has better thrust efficiency and a long endurance than propeller. Thrust characteristics of hover and for ward flight condition for the ducted fan UAV is important issue to improve a endurance. The unsteady 3-dimensional flow fields of the ducted fan UAV is essential to stable flight. In this paper, to verify the design results of the ducted fan and to investigate a stable aeronautical characteristic, the thrust performance and the unsteady 3-dimensional flow fields are measured. Thrust characteristics for the hovering and the forward flight conditions are measured by the 6-components balance system in the subsonic wind tunnel. The unsteady 3-dimensional flow fields are analyzed by using a stationary $45^{\circ}$ slanted hot-wire technique. The swirl velocity is almost removed behind the stator blades. Therefore, the thrust performance of the ducted fan is improved and the flight stability is maintained.

• Journal of the Korean Institute of Gas
• /
• v.18 no.4
• /
• pp.51-55
• /
• 2014

This paper was analyzed for a sealing characteristics of single lip contact type o-ring and multiple lip contact type packing for a swivel joint using the finite element method. According to the FE analysis, a conventional o-ring produces a maximum contact normal stress of 2.5MPa for a supplied LP gas pressure of 1.8MPa, which is related to the sealing performance. But, a sealing performance of newly invented multi-lip packing produces a maximum contact normal stress of 3.01MPa, which is 20.4% higher than that of a conventional o-ring. And an extrusion of a conventional o-ring, which is strongly related to the sealing endurance safety, was occurred at a supplied gas pressure of 1.62MPa. But, a multi-lip packing does not produce up to the gas pressure of 1.8MPa. This means that a new type of multi-lip packing may have excellent sealing characteristics because of no extrusion for high gas pressure. Thus, multi-lip packing with multiple lip contacts may be useful for high sealing and endurance safety compared to that of the conventional o-ring with a single lip contact.

• Physical Therapy Rehabilitation Science
• /
• v.7 no.2
• /
• pp.88-93
• /
• 2018

Objective: Elevated cholesterol levels contribute to changes of the arterial endothelial permeability. Hyperlipidemia promotes atherosclerosis and is associated with an increased risk of stroke incidence. The purpose of this study was to investigate the effects of having a history of hyperlipidemia prior to a stroke incidence on postural balance, anticipatory dynamic postural control, gait endurance and gait performance in individuals with hemiparetic stroke. Design: Cross-sectional study. Methods: Fifty-two adults who were diagnosed with stroke 6 months ago or more were enrolled in this study. They were divided into two different groups according to hyperlipidemia history before stroke. All participants were assessed with the Activities-specific into Balance Confidence (ABC) scale, Berg Balance scale (BBS), Dynamic Gait Index (DGI), Timed Up and Go test (TUG), and the 6-minute walk test (6MWT). An independent t-test was used to analyze the difference between the hyperlipidemia group and non-hyperlipidemia group. Results: After analysis, the BBS, TUG, and 6MWT scores were significantly different between the hyperlipidemia and non-hyperlipidemia group, but not the ABC and DGI scores. Conclusions: The results of this study show that having a history of hyperlipidemia before stroke affects static and dynamic postural balance performance, anticipatory dynamic postural balance, and gait endurance in individuals with chronic hemiparetic stroke. Based on the results of this study, we also suggest treatment for hyperlipidemia should be implemented throughout the therapeutic interventions, such as pharmacological or exercise programs, in order to restore the physical function of stroke survivors.