• Journal of the Korean Society of Safety
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• v.22 no.5
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• pp.13-20
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• 2007

Elastomeric O-ring seals are widely used in static and dynamic applications. A compressed and highly pressurized O-ring seal inserted under laterally one-sided constrained condition has been analyzed experimentally and numerically. The deformed shape and extrusion length of the O-ring under high pressure has been measured by the computed tomography. Through the comparison of experimental and FE results, the numerical analysis technique has been verified. Using verified FE method, the contact stress profiles at sealing surfaces have been investigated and their relevance to the 0-ring performance evaluated based on stress-related and displacement-related parameters. It has been found that the contact stress profiles and deformation behaviors of the seal are affected by friction coefficient, gap clearance, and pressure considerably.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1185-1189
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• 2007

In this paper, to improve the efficiency of pressurized pneumatic grit conveying for ship block open blasting process. Pressurized pneumatic grit conveying is defined as the transportation of grit(abrasive) in a compressed air flow. Total Pressure loss in flexible hose for pneumatic conveying is sum of pressure losses due to gas and grit and needle type pressure transmitter for measured pressure loss. haracteristics of grit open blasting by pneumatic conveying were studied experimentally. Studies variables were blasting nozzle ID, length and ID of flexible hose, grit flow rate, flow rate and pressure of transport air. It was experimentally proved that optimal open blasting condition and cost effective operation regarding grit blasting, obtaining a high qulity surface preparation(Sa $2^{\frac{1}{2}}$).

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.86-93
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• 2009

Elastomeric O-rings have been the most common seals due to their excellent sealing capacity, and availability in costs and sizes. One of the critical applications of O-ring seals is solid rocket motor joint seal where the operating hot gas must be sealed during the combustion. This has long been a design issue to avoid the system failure. For laterally constrained, squeezed and pressurized condition, deformed shape of O-ring was measured by computed tomography method and CCD laser sensor, compared with numerical calculations. As clearance gap changes, sealing performance had been evaluated on peak contact stresses at top, bottom and side contact surfaces. As clearance gap increases, peak contact stresses and contact widths in top and side contact surfaces increase, and the asymmetry of stress distributions is promoted due to pressure increase. It is suggested that peak stress of bottom contact surface can be approximated by simple superposition of peak ones due to squeeze and pressure. Under pressurized condition, sealing performance is dependent on not peak stresses of bottom and side contact surfaces but that of top.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1511-1519
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• 2014

The objective of this paper is to propose a modelling of a small compressed air energy storage system, which drives an induction generator based on a field-oriented control (FOC) principle for a renewable power generation. The proposed system is a hybrid technology of energy storage and electrification, which is developed to use as a small scale of renewable energy power plant. The energy will be transferred from the renewable energy resource to the compressed air energy by reciprocating air compressor to be stored in a pressurized vessel. The energy storage system uses a small compressed air energy storage system, developed as a small unit and installed above ground to avoid site limitation as same as the conventional CAES does. Therefore, it is suitable to be placed at any location. The system is operated in low pressure not more than 15 bar, so, it easy to available component in country and inexpensive. The power generation uses a variable speed induction generator (IG). The relationship of pressure and air flow of the compressed air, which varies continuously during the discharge of compressed air to drive the generator, is considered as a control command. As a result, the generator generates power in wide speed range. Unlike the conventional CAES that used gas turbine, this system does not have any combustion units. Thus, the system does not burn fuel and exhaust pollution. This paper expresses the modelling, thermodynamic analysis simulation and experiment to obtain the characteristic and performance of a new concept of a small compressed air energy storage power plant, which can be helpful in system designing of renewable energy electrification. The system was tested under a range of expansion pressure ratios in order to determine its characteristics and performance. The efficiency of expansion air of 49.34% is calculated, while the efficiency of generator of 60.85% is examined. The overall efficiency of system of approximately 30% is also investigated.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.2
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• pp.184-193
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• 2020

One of the technical methods to increase the volumetric energy density of hydrogen is to pressurize the gaseous hydrogen and then contain it in a rigid vessel. Especially for automotive systems, the compressed hydrogen storage can be found in cars as well as at refueling stations. During the charging the pressurized hydrogen into a vessel, the temperature increases with the amount of stored hydrogen in the vessel. The temperature of the vessel should be controlled to be less than a limitation for ensure stability of material. Therefore, the accurate estimation of temperature is of significance for safely storing the hydrogen. In this work, three well-known cubic equations of state (EOSs) were adopted to examine the accuracy in regenerating thermodynamic properties of hydrogen within the temperature and pressure ranges for the compressed hydrogen storage. The formulations representing molar volume, internal energy, enthalpy, and entropy were derived for Redlich-Kwong (RK), Soave-Redlioch-Kwong (SRK), and Peng-Robinson (PR) EOSs. The calculated results using the EOSs were compared with literature data given by NIST. It was revealed that the accuracies of RK and SRK EOSs were satisfactorily compatible and better than the results by PR EOS.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.2
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• pp.47-57
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• 1984

The porous matterials are used both to control the flow of the compressed gas and to serve as the bearing surface. This porous design offers several advantages over the conventional externally pressurized gas bearings. It can simplify the construction, lower the gas consumption, and make the cleaning of the gas supply less critical. Test apparatus was cinstructed to experi- mentally investigate maximum load capacity of thrust bearing was measured 200 Kg (15Kg/$\mu$m), and radial bearing was 36 Kg/$\mu$m. And a rotation accuracy of face waving was 0.0127$\mu$m, and center waving was measured 0.5 $\mu$m. Finally, the use of this method of design and manufacturing will contribute to many practical application in the field required for precision and high stability.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.69-76
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• 1998

A precision wear tester is developed to measure the wear rate of a high friction and high pressurized cylinder. The tester consists of indentor system and optical measuring system. The indentor system has two diamond indentors so that they make indents on the inside of the cylinder by using compressed air system. The X-Y-$\theta$ stage of the measuring system can trace the positions of the indents and can measure the diameters of them. The variation of the diameter of each indent after test is converted into the wear rate.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.241-247
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• 2003

The sealing performance of O-ring is effected in environments of the O-ring seal, like that applied pressure, working temperature, pre-compressed ratio and materials. In this paper, design of composite O-ring under pressurized, compressed was optimized based on Taguchi experimental design method. and it analysed numerically using non-linear finite element method. Ogden model in which is developed based on the experimental data is used for simulating the contact stress and strain in NBR and PTFE materials. Sensitivity analysis was performed with FEM results, which are contact stress, strain and temperature as variable.

• Tribology and Lubricants
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• v.20 no.5
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• pp.259-265
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• 2004

The sealing performance of O-rings is affected by working conditions such as applied pressure, operation temperature, pre-compressed ratio and material properties. In this paper, a pressurized and compressed elastomeric bi-polymer O-ring in which is inserted into a rectangular groove is analyzed by non-linear MARC finite element program based on the Taguchi experimental method. O-rings with 9 different profile models are analyzed for design parameters that are related to the diameter ratio between outer diameter and inner one of bi-polymer O-ring, compressive ratio, groove angle and groove depth. The calculated FEM results showed that the affection ratio of design parameter dlD, which may control sealing pressure of O-rings, is the most influential parameter among the groove angle, groove depth and compression ratio.

• Journal of Drive and Control
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• v.12 no.4
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• pp.15-20
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• 2015

Unlike a typical metal spring, a gas spring uses compressed gas contained in a cylinder and compressed by a piston to exert a force. A common application includes automobiles where gas spring are incorporated into the design of open struts that support the weight of tail gate. They are also used in furniture such as office chairs, and in medical and aerospace applications. The gas spring works by the application of pressurized gas (nitrogen) contained in a cylinder. The internal pressure of the gas spring greatly exceeds atmospheric pressure. This differential in pressure exists at any rod position and generates an outward force on the rod, making the gas spring extend. In this paper, we investigated the dynamic characteristics of a gas spring on an automotive tail gate system.