• Journal of the Korean Society of Physical Medicine
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• v.18 no.1
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• pp.15-24
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• 2023

PURPOSE: This study examined the effects of lowintensity resistance exercise combined with blood flow restriction on muscle activity and muscle fatigue to determine if such a combination may be an alternative to high-intensity resistance exercise in maintaining the muscle mass and strength and preventing degenerative loss of skeletal muscle and to provide basic data for presenting the effectiveness of exercise. METHODS: The interventions were provided for five weeks, four sessions a week, once a day, 60 minutes a session to Experimental group I (n = 13), in which low-intensity resistance exercise was applied by combining blood flow restriction with the biceps curl and experimental group II (n = 12), in which only high-intensity resistance exercise was applied. As a pre-test, the biceps brachii muscle activity and fatigue were measured by surface electromyography, and the hemodynamic variables, such as blood pressure and heart rate, were measured. The post-test was performed identically to the pre-test and compared and analyzed with the pre-test. RESULTS: A significant difference within-group was observed in the biceps brachii muscle activity and fatigue in experimental group I and only in biceps brachii activity in experimental group II. No significant differences were observed between the two groups. CONCLUSION: Since the low-intensity resistance exercise combined with blood flow restriction has similar effects to high-intensity resistance exercise, it is considered an alternative for improving muscle function in groups unable to perform high-intensity resistance exercise.

• Journal of the Korean Magnetics Society
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• v.12 no.6
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• pp.224-230
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• 2002

The statistical experiment method is employed to optimize the deposition condition of Co film with DC magnetron sputtering process. The statistical treatment results showed the significance value below 0.05, low RMS error and R-sq value close to 1, which implied that our experiment and design were very reliable. We found that the sheet resistance decreased to -1.83Ω/$\square$ with the deposition temperature, increased to 11.17Ω/$\square$ with the deposition pressure, and decreased into -0.65Ω/$\square$ with the DC power. We also confirmed that the sheet resistance uniformity was mainly influenced by the deposition temperature as it decreased -4.04％ at the temperature range of 25$\^{C}$∼147$\^{C}$. Finally, we report that the optimum condition of Co film using our statistical method of design of experiment is the deposition temperature of 25$\^{C}$, the deposition pressure of 12mTorr, and the DC power of 1500W.

• Wind and Structures
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• v.14 no.5
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• pp.383-411
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• 2011

Roof is an integral part of building envelope. It protects occupants from environmental forces such as wind, rain, snow and others. Among those environmental forces, wind is a major factor that can cause structural roof damages. Roof due to wind actions can exhibit either flexible or rigid system responses. At present, a dynamic test procedure available is CSA A123.21-04 for the wind uplift resistance evaluation of flexible membrane-roofing systems and there is no dynamic test procedure available in North America for wind uplift resistance evaluation of rigid membrane-roofing system. In order to incorporate rigid membrane-roofing systems into the CSA A123.21-04 testing procedure, this paper presents the development of a load cycle. For this process, the present study compared the wind performance of rigid systems with the flexible systems. Analysis of the pressure time histories data using probability distribution function and power spectral density verified that these two roofs types exhibit different system responses under wind forces. Rain flow counting method was applied on the wind tunnel time histories data. Calculated wind load cycles were compared with the existing load cycle of CSA A123.21-04. With the input from the roof manufacturers and roofing associations, the developed load cycles had been generalized and extended to evaluate the ultimate wind uplift resistance capacity of rigid roofs. This new knowledge is integrated into the new edition of CSA A123.21-10 so that the standard can be used to evaluate wind uplift resistance capacity of membrane roofing systems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.1
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• pp.9-15
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• 2011

In this study, we investigated the hydrodynamic and thermal performance of constructal architectures on the basis of the mass flow rates for a given pressure drop, and we determined the thermal resistance and flow uniformity. The five flow configuration used in this study were the first construct with optimized hydraulic diameter, the second construct with optimized hydraulic diameter, the first construct with non-optimized hydraulic diameter, second construct with non-optimized hydraulic diameter, and a serpentine configuration. The results of our study suggest that the best fluid-flow structure is the second constructal structure with optimized constructal configurations. We also found that in the case of the optimized structure of cooling plates, the heat transfer was remarkably higher and the pumping power was significantly lower than those of traditional channels.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.118-125
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• 2011

Conventional erosion function apparatus (EFA) which has been used to measure the hydraulic resistance of soil was improved to consider direction change of the current flow. Using improved apparatus, hydraulic resistance capacities of the artificially composed clayey soil and sandy soil were compared. Test result shows that scour rates which were measured under the bi-directional flow were much higher than those measured under unidirectional flow for both type soils. Scour rate of sandy soil was higher than that of clayey soil. Velocity averaged scour rate of specimen which was consolidated under the relatively large consolidation pressure is higher than that of specimen which is consolidated under small consolidation pressure, which means scour problem under bidirectional flow may be more serious for the deep seabed ground.

• Journal of Adhesion and Interface
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• v.7 no.3
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• pp.16-25
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• 2006

Water vapour permeable and water resistant film was laminated to made footwear woven fabric and non-woven fabrics by screen type with thermosetting reactive hot melt adhesive. Optimum conditions of each process were investigated, and the properties of film laminated fabric with optimum conditions are evaluated. The results are as follows. Thermosetting reactive polyurethane hot melt is retain proper heat resistance differently thermoplastic hot melt. Optimum melting adhesive process conditions are as follows ; drum temperature $95^{\circ}C$, hose temperature $97^{\circ}C$, feeding pipe temperature $100^{\circ}C$, screen temperature $105^{\circ}C$, pressure of opposite roller $1kgf/cm^2$, pressure of laminating roller $3kgf/cm^2$, finishing speed 15 m/min, melting temperature $120^{\circ}C$, cooling time 20 s, pressing temperature $130^{\circ}C$, pressing time 30 s. As the thickness of film was increased, the water vapour permeability was decreased but water resistance was increased, and the effect of film is dominant over all the others in the air permeability.

• The Journal of Korean Physical Therapy
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• v.22 no.1
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• pp.9-17
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• 2010

Purpose: The purpose of this study was to compare the effects of Tai-Chi exercise (TCE) and resistance exercise (RE) when used as part of a community-based exercise program on improvement of physical function in elderly women with knee arthritis. Methods: Forty-seven women with knee arthritis participated in this study. They were assigned to one of two groups: the TCE group (n=22) or the RE group (n=25). Tai-Chi exercise and resistance exercise sessions were held for 1 hour per session, twice per week, for 8 consecutive weeks. At pre-treatment and post-treatment, subjects were tested using the following measurements: one-legged stand test (sec), a functional reach test (cm), a test of the strength of the knee extensor and flexor muscles, determination of the pathway of center of foot pressure and vertical ground reaction force for stance phase at pre and post treatment time points. An independent t-test and a ${\chi}^2$ were used to determine the significance of differences between group means using SPSS 12.0. Results: After 8 weeks of participation in the exercise programs, there were significant improvements for both groups in joint pain, difficulty of performing activity, muscle strength of knee extensor and flexor. Also, vertical ground reaction force increased at the loading response phase for both groups. The RE group was significantly different from TC group on the eyes-closed one-legged stand test (sec). Conclusion: Tai-Chi exercise and resistance exercise programs improve physical functioning and reduce pain and locomotion difficulties.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.83-88
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• 2004

In this study, the flow and thermal performance of the heat sink and fan-sink were experimentally studied to predict the operating condition of the fan-sink. The experiments of the flow and thermal resistance of the heat sink with various inlet blockage, which were occurred by the shapes of the axial fans, were conducted for the proof of the effects of the inlet blockages. The greater the inlet blockage of the heat sink, the higher the pressure drop and lower the thermal resistance of the heat sink will be. The operating point of the fan-sink was predicted by the pressure drop curve with the inlet blockage, which was corresponded to the selected fan and the fan performance curve, and verified by the performance test of the fan-sink. The predicted operating point of the fan-sink had good agreement with the result of the performance test of the fan-sink within $0.7\%$ of the volume flow rates. Measured thermal resistance of the fan-sink was equivalent to that of the heat sink with the same inlet blockage of the fan-sink. It was shown that the heat transfer characteristics of the heat sink were influenced by the flow interaction between the selected fan and the heat sink. To improve the thermal resistance of the heat sink, it is necessary to consider appropriate flow patterns of the fan outlet entering into the heat sink.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.99-111
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• 1999

The frictional capacity of auger-cast piles is often very small because of the disturbance of the soil surrounding the pile during the excavation process. Usage of expansive agents and a pressurized injection technique for auger-cast piles should improve the frictional resistance between pile and soil. This paper presents the test results of auger-cast model piles installed with expansive mortar in laboratory compacted weathered soil. The model piles were installed in a calibration chamber with a variation in the amount of expansive agent, the injection process and the chamber pressure. It was observed that the pile shaft resistance increases with the increased amount of expansive agent, and also increases when mortar is pressure injected. The shaft resistance increased up to 24% for the pile installed only with expansive mortar and increased up to 56% for the pile installed with the pressurized injection of expansive mortar, compared with that of piles with plain mortar.

• Composites Research
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• v.36 no.6
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• pp.422-428
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• 2023

The electrical contact resistance between the bipolar plate (BP) and the carbon felt electrode (CFE), which are in contact by the stack clamping pressure, has a great impact on the stack efficiency because of the relatively low clamping pressure of the vanadium redox flow battery (VRFB) stack. In this study, a polyethylene (PE) composite-CFE hybrid bipolar plate structure is developed through a local heat welding process to reduce such contact resistance and improve cell performance. The PE matrix of the carbon fiber composite BP is locally melted to create a direct contact structure between the carbon fibers of CFE and the carbon fibers of BP, thereby reducing the electrical contact resistance. Area specific resistance (ASR) and gas permeability are measured to evaluate the performance of the PE composite-CFE hybrid bipolar plate. In addition, an acid aging test is performed to measure stack reliability. Finally, a VFRB unit cell charge/discharge test is performed to compare and analyze the performance of the developed PE composite-CFE hybrid BP and the conventional BP.