• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.1-7
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• 2013

Pneumatic cylinders are widely used to actuators in automatic equipments because they are relatively inexpensive, simple to install and maintain, offer robust design and operation, are available in a wide range of standard sizes and design alternatives. This paper presents a comparative study among the dynamic characteristics of meter-out and meter-in speed control of pneumatic cushion cylinders with a relief valve type cushion mechanism. Because of the nonlinear differential equations and a requirement for simultaneous iterative solution in a mathematical model of a double acting pneumatic cushion cylinder, a computer simulation is carried out to investigate pressure, temperature, mass flow rate in cushion chamber and displacement and velocity time histories of piston under various operating conditions. It is found that the piston velocity and pressure response in meter-in speed control are more oscillatory than with meter-out those when pneumatic cushion cylinders are driven at a high-speed. In meter-out speed control, the effective area of the flow control valve is larger than that of meter-in, and the supply pressure has to be much higher than the pressure required to move the load because it has also to overcome the back pressure in cushion chamber.

• 연구논문집
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• s.28
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• pp.73-87
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• 1998

A pneumatic control system of compressed air as a working fluid has a variety of advantages such as low price, high respondence, non-explosion and good control performance and thus has many applications in the field of automobile, electronic and semiconductor industry. However, it has a difficulty in contolling a precise position due to quick response of system and compressibility of working fluid and. in particular, shock stress may occur due to an external load, resulting in fracture of a cylinder cap unless cushion device is equipped in the linear actuator. To avoid this, a cushion device should be installed for damping effect of the external load and the supply pressure as well as for decreasing shock stress and vibration caused by high speed rotation. Previous studies include dimensionless analyses and computer simulations of cushion capability and experiments of horizontally-mounted cylinder performances. A new attempt is experimentally made in this study using a vertically-mounted cylinder under an operation condition of 4, 5 and 6 (bar) as supply pressure and 40, 70 and 100 (kgf) as external load. It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure. The cushion characteristics was also revealed in the meter-in circuit.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.7-12
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• 2011

The crash cushion has drawn a great attention because of its versatility, efficiency and simplicity in reducing the mortality and damages from traffic accidents. However, the existing cushion systems are high priced or have limited functions. The purpose of the study was to devise an improved crash cushion which can offer higher safety compared to the available ones at present. In addition, the conformity of the cushion with the facility standards was assessed through computer simulation for collision with vehicles. The novel cushion system adopts the used tires as shock absorber, which can not only secure cushioning effect but also reduce the production cost. Moreover, it is highly durable and easy to maintain and repair the damaged parts. According to the simulation using BARRIER VII program, the novel cushion system showed PHD of 17.4 g and 10.1 g for a frontal collision and a side collision, respectively. Based on the results, it could be concluded that the novel cushion system met the test standards in the guideline for road safety facility installation and management.

• International Journal of Highway Engineering
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• v.9 no.3
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• pp.91-100
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• 2007

The most important thing for driver's safety on the road is equipment of crash cushion as a vehicle protection safety facility. But development of crash cushion is defective because there's no rational and reality way of design. And also without an alternative plan, it rely on crash test hereby it suffers a great economic loss and wastes time. This study that uses data of cash test proves the suitability of single degree of freedom which considers the safety of passengers about three-dimensional complicated Crash Analysis. As the study analyzes the conduct of crash cushion, it want to develop the effective method of design on Single Degree of Freedom Crash Cushion. And it presents the way of crash cushion design through making a crash analysis model with single degree of freedom. To verify the validness of the crash cushion plan, with single degree of freedom plan, we make the level CC2 crash cushion and execute the crash test. A performance test brings satisfied result and a plan of single degree of freedom crash cushion is proven as an one of the way to be a good system which can design crash cushion.

• 기계와재료
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• v.11 no.2 s.40
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• pp.53-61
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• 1999

The paper describes a characteristics analysis for cushion pressure and cushion stroke time at hydraulic cushioning cylinder. In hydraulic cushioning cylinder, an inertia exaggerates a kinetic energy at a reciprocation that collide with an end of stroke and generate a destructive shock, noise and vibration within the structural and operating member of machine of equipment. In order to reduce which cause to undesirable noise, vibration and fatigue in hydraulic control system, it is indispensible measure a cushion parameters at cushion region of hydraulic cushioning cylinder. A cushioning device is applied to absorb high impact energy and to decelerate a fast travelling object, too. At an experimental results, it turns out that cushion pressure is mainly a function of the external load and cylinder input flowrate rather than the supply pressure.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.301-301
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• 2000

It is well known, for many years, that deep drawability ,can be improved by applying variable blank holding force. To apply variable blank holding force during cup during, we set up pressure controlling system on experimental hydraulic press, and the pressure control system is often called NC(Numerically Controlled} cushion system. Using the NC cushion system we carry out pressure control experiment and the proposed structure shows good performance. And we compare drawability of square steel cups with NC cushion and that with conventional cushion. The results show drawability is greatly improved when the pressure control curve is designed in a S-shaped curve. This paper includes design details of the NC cushion system and experimental analysis of drawability with experimental NC cushion system.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.1
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• pp.35-40
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• 2006

Cushioning systems, which are cushion material and its designed configuration, are important to protect fragile items since they act as buffers between the impact force and the fragile product. As cushioning materials, several plastic foams are commonly used in industry. However, the utilization of the plastic material has been causing a solid waste problem and pollution. Thus, as an alternative cushion material to the plastic foams, a corrugated cushion, which is considered environmentally friendly and cheap material, was put into drop tests and its impact shock attenuation was investigated. Flat and free drop data were recorded and compared to the dynamic shock of EPS cushion. In addition, the mathematical model of the shock attenuation of the corrugated cushion was developed. The result showed that the corrugated cushion gave an excellent protection for items that were subjected to the limited number of drops. There was no significant difference of the shock absorbing ability between the EPS and corrugated cushions. Energy density model of cushioning material successfully explained the mechanical behavior and fatigue of the corrugated cushions.

• Textile Coloration and Finishing
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• v.34 no.3
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• pp.173-184
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• 2022

In this study, the TPU film was laminated on an aramid fabric or circular knits in order to implement an air cushion material that can respond to high impact forces in case of a fall and is easy to expand. To increase the bonding strength between the fabric layer and the film layer, a primer layer was formed in two ways: one for thermally bonding and laminating PET film and two for coating and aging hot melt type PUR adhesive. The tensile strength of the aramid air cushion was 2.5 times higher than that of the circular knits, but the tensile elongation of the aramid air cushion was very low compared to that of the circular knits. The tear strength of the aramid air cushion was about twice or more superior to that of the circular knits, the primer treatment method was good at A, and the peel strength was excellent at method A. The aramid air cushion was the lightest in weight. Summarizing the above results, it was best to combine the air cushion material with aramid woven fabric and primer treatment method A to cope with the high impact force applied when falling.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.435-439
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• 2002

In the pneumatic system, pneumatic cylinder is wildly used to factory automation. In general, Pneumatic cylinder problems are occured with colliding to stroke end part at which piston collide to end-cap, head cap and tube when piston is loading. This appearances have a short life of cylinder and is due to system destruction. This study examines the dynamic characteristics of pneumatic cushioning cylinder and cushion sleeve design. At head part cushion chamber for the vertical experimental, The decisions of cushioning effect and the results of the experimental research are obtained to the followings: i) The cushioning effects could acqure to the reserch, if the compressible energy is more than kinetic ones. ii) The collision of piston and head cover could acqure to the research, if the kinetic energy is more than compressible iii) If the load increase to the rolling car, the cushion region pressures would increase and the dynamic force.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.38-47
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• 2020

The partial air cushion supported catamaran (PACSCAT) is a novel Surface Effect Ship (SES) and possesses distinctive resistance performance due to the presence of planing bottom. In this paper, the design of PACSCAT and air cushion system are described in detail. Model tests were carried out for Froude numbers ranging from 0.1 to 1.11, the focus is on the influence of air cushion system on resistance characteristics. Drag-reducing effect of air cushion system was proved by means of contrast tests in cuhionborne and non-cushionborne mode. Wave-making characteristics reflect that the PACSCAT would eventually enter planing regime, in which the air could just escape under the seals and the hull body could operate in a steady state. To acquire different air cushion pressure, air flow rate and leakage height were adjusted during tests. Experimental results show that the resistance performance in planing regime would decrease evidently as the increased air flow rate, however, the scheme with medium leakage height presents the best resistance performance in the hump region.