• PNF and Movement
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• v.13 no.1
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• pp.47-53
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• 2015

Purpose: This study examined the effects of space fabric type air insole pressure differences on young adults' dynamic balance ability. Method: The subjects of this study were 17 young female adults without musculoskeletal system disease. Balance ability was measured by dividing the subjects into three groups: an experimental group which did not wear an air insole (insole-off group), an experimental group which wore an air insole to which air pressure of $0.55kg/cm^2$ was applied (insole-0.55 group), and an experimental group which wore an air insole to which air pressure of $0.75kg/cm^2$ was applied (insole-0.75 group). For dynamic balance, the subjects stood on a balance pad, and perimeter length and medium speed were measured three times. The averaged values were recorded and statistically processed. Result: There were significant differences in average speed, and the insole-0.75 group's average speed decreased compared to the insole-off group and the insole-0.55 group. Although the total movement distance did not statistically differ, the insole-75 group's movement distance decreased compared to the insole-off group and the insole-0.55 group. Conclusion: Application of a space fabric type air insole, in particular insole-0.75, was helpful in improving balance ability. This is considered to occur because the space fabric structure was conducive to decreasing sway and producing balance.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.117-122
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• 2009

The hexagonal network-type PDMS microstructures were fabricated and they were employed to low-friction drag surfaces. While the lowest contact angle measured from the smooth surface was $108^{\circ}$ the highest contact angle measured from the microstructured surfaces was $145^{\circ}$ The moving speed of bullet-type capsule attached with a PDMS pad of smooth surface ($CA=108^{\circ}$) was 0.1261 m/s and that with a PDMS pad of microstructured surface ($CA=145^{\circ}$) was 0.1464 m/s. Compared with the smooth surface, the microstructured surface showed 16.1% higher moving speed. The network-type microstructures have a composite surface that is composed with air and PDMS solid. Therefore, the surface does not wet: rather water is lifted by the microstructures. Because of the composite surface, water shows slip-flow on the microstructures, and thus friction drag can be reduced.

• Design & Manufacturing
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• v.14 no.3
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• pp.37-43
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• 2020

Progressive drawing processing is one of the manufacturing processes used to mass-produce a variety of products on the industrial site. In this study, the goal is to achieve a uniform product thickness of at least 1.3mm by reducing the wall thickness of the coupler parts used in automotive air conditioning systems to within 15% using A5052-H32 materials. The progressive die was designed using Blank's law of volume invariance. Due to the characteristics of the drawing process, the material thickness in the punch R part decreases and the thickness in the die R part increases. When designing the progressive die of the coupler part, an ironing method, a push back method, and a stand-alone die pad method were applied to each process to design a mold in consideration of the drawing rate and to artificially adjust the thickness change. The suitability of the method used in die design was investigated by measuring the thickness change of forming parts for each process. In the final part, it was confirmed that the thickness measurement values of the five regions of a radial line were implemented as 1.34-1.36 mm.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.332-338
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• 1999

A coupled thermal-mechanical analysis has been presented for the thermal distortions of the ventilated disk brakes during IS braking operations. The FEM results show that the bendings and distortions of the disk toward the left side are decreased, but the sinusoidal distortion of the disk rubbing surface along the arc length of the vent hole is highly increased by increasing the convective air cooling effects, which is heavily related to the squeal, wear and micro-thermal crackings at the rubbing surfaces due to uneven dissipation rates of friction heatings.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.1
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• pp.9-16
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• 2009

Cylindrical dry forming mould was developed to carry out a feasibility study of dry forming of papers. The effect of disintegration, forming, humidification and pressing on dry formed papers was examined. Dry disintegrated fibers showed the similar fiber length distribution to wet disintegrated fibers, but they showed distorsion and damaged appearance on the surface. Process parameters required to form a uniform fiber pad was investigated. A proper screening and air dispersion method was selected that gives proper formation. Humidification and pressing conditions were examined to get a good dry formed papers in dry forming. Results showed that dry forming method can be used to make a sheets with reasonable formation and properties.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.149-156
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• 2007

Non-contact transportation of the large-sized glass plate using air-cushion is considered for sputtering system of LCD panel. The Argon gas from second gas injection holes is injected to levitate and transport the glass plate. Low maximum pressure and uniform pressure distribution on the bottom surface of the glass plate must be maintained for stable levitation and transportation of the glass plate. Therefore, the analysis of fluid flow between the glass plate and the air-pad is numerically performed for varying space between the injection holes in this study. The pressure uniformity on the bottom surface of the glass plate is evaluated for overall glass plate. The distance between the injection holes must be designed below 90 mm for obtaining the low maximum pressure and uniform pressure distribution.

• Tribology and Lubricants
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• v.15 no.2
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• pp.199-205
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• 1999

Using a coupled thermal-mechanical analysis, the thermal distortion of the ventilated disk brakes has been investigated based on the air cooling effects during 15 braking operations. The FEM results show that the bendings and distortions of the disk toward the left side are decreased, but the sinusoidal distortion of the disk rubbing surface along the arc length of the vent hole is highly increased by increasing the convective air cooling effects, which is heavily related to the squeal, wear and micro-thermal crackings at the rubbing surfaces due to uneven dissipation rates of friction heatings.

• Tribology and Lubricants
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• v.36 no.1
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• pp.39-46
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• 2020

Air stages are usually applied to precision engineering in sectors such as the semiconductor industry owing to their excellent performance and extremely low friction. Since the productivity of a semiconductor depends on the acceleration and deceleration performance of the air stage, many attempts have been made to improve the speed of the stage. Even during sudden start or stop sequences, the stage should maintain an air film to avoid direct contact between pad and the rail. The purpose of this study is to quantitatively predict the dynamic behavior of the air stage when acceleration and deceleration occur. The air stage is composed of two parts; the stage and the guide-way. The stage transports objects to the guideway, which is supported by an externally pressurized gas bearing. In this study, we use COMSOL Multiphysics to calculate the pressure of the air film between the stage and the guide-way and solve the two-degree-of-freedom equations of motion of the stage. Based on the specified velocity conditions such as the acceleration time and the maximum velocity of stage, we calculate the eccentricity and tilting angle of the stage. The result shows that the stiffness and damping of the gas bearing have non-linear characteristics. Hence, we should consider the operating conditions in the design process of an air stage system because the dynamic behavior of the stage becomes unstable depending on the maximum velocity and the acceleration time.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.25-31
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• 2003

Airborne contaminant particles are intruded into optical disk drives(ODD) due to the flow caused by disk rotation and can be adhered to lens or disk surfaces, which causes decrease of laser power and increase of read/write errors. Such a phenomenon can be more serious as the space between the disk and the lens is reduced fur high-density storage devices. The purpose of this paper is to understand design parameters to reduce the particle intrusion into an ODD. Suggestions are made to prevent the particle intrusion that can decrease the stability of an ODD and also prevent the potential heat build-up problem. The sealing effect of drive and the forced injection of clean air (using HEPA filter) into the drive minimizes intrusion of the outside air and dusts in an ODD remarkably. Moreover it is proved by experiments that the installation of a heatproof pad to isolate heat generation part (PCB) from information read/write sections and the forced injection of dust-free air reduce the gas temperature inside the drive as well as the amount of particles intruded.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.10
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• pp.235-243
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• 2019

In South Korea, millions of poultry have died due to repeated heat waves every year. The purpose of this study is to analyze the characteristics of heating and cooling loads of chicken houses in Korea and to present an effective insulation and ventilation measures to minimize the damage of poultry due to summer heat wave and to save energy in chicken houses in winter. The heating and cooling loads of standard chicken house were calculated. As a result of the calculation of maximum heating load based on the minimum ventilation rate in winter, the outdoor air temperature requiring heating was $6{\sim}7^{\circ}C$ to keep the indoor air temperature of chicken houses as $24^{\circ}C$. The peak cooling load of chicken houses was mostly taken by the heat generated by chickens and the heat gain due to ventilation. The heat gain through building envelopes was as small as neglectable. Most of chicken houses is usually cooled by gigantic forced ventilation in summer in Korea. When the chicken houses are cooled by electric cooling machine such as cooler or air conditioner, it is more effective to keep minimum ventilation rate to reduce the maximum cooling load. To lower the temperature of supplying water to cooling pad, it is recommended to use the underground water below 10 meters from the ground if there is abundant underground water.