• Journal of the HCI Society of Korea
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• v.1 no.2
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• pp.19-26
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• 2006

This paper presents a novel pneumatic tactile display that can deliver some useful information. The air-jet display forms 5 by 5 arrays and features air nozzles with an external diameter of 2.4mm and internal diameter of 1.5 mm. In comparison with other tactile displays such as vibrotactile, there is little concrete psychophysical data relating to pneumatic displays, a fact which hinders their adoption. This paper addresses this challenge, and presents brief psychophysical studies examining localization rate, the two point threshold, stimulus intensity and the temporal threshold of cues produced by pneumatic air jets. Two groups of subjects were used in these studies, subsequently termed groups A and B. Both were comprised of eight participants. In the case of localization study we obtained 58.13% and 85.9% of localization rates each for dense display and sparse display. Two-points threshold test showed the length of gap between two air-jet stimuli which subjects can detect. However, it was formidable to find out precise temporal resolution of PTI owing to the limitation of capability of the pneumatic valves. Lastly, the results of stimulus intensity study suggest that by varying the size of a pneumatically created tactile stimulus, we can effectively vary its perceived magnitude.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.46-52
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• 2012

A PAEM(Pneumatic Active Engine Mount) system has been developed to improve NVH performance of a SUV in idle state. Control objective to attenuate the vibration of a vehicle should be determined prior to the design of control algorithm. This study presents the correlation analysis of output variables of PAEM system by means of TPA(Transfer Path Analysis) using experimental data obtained by vehicle test. The analysis results show that the vibration of vertical direction is more serious than those of longitudinal and lateral direction of the vehicle, and that the correlation between the vibration of front seat rail and that of steer wheel is highest. In conclusion, the vibrations of front seat rail and steer wheel in vertical direction should be considered as the control objectives of the PAEM.

• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.22-28
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• 2006

The motion and wave drift forces of floating BBDB (backward-bent duct buoy) wave energy absorbers in regular waves are calculated, taking account of the oscillating surface-pressure due to the pressure drop in the air chamber above the oscillating water column, within the scope of the linear wave theory. A series of model tests has been conducted in order to order to verify the motion and time mean wave drift force reponses in regular waves at the ocean engineering basin, MOERI/KORDI. The pneumatic damping through an orifice-type duct for the BBDB wave energy device are deducted from experimental research. Numerical simulation for motion and drift force responses of the BBDB wave energy device, considering pneumatic damping coefficients, has been carried out, and the results are compared with those of model tests.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.163-167
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• 1993

We developed a ventricular assist device(VAD) to be used as a bridge to heart transplantation or a circulatory assist device for patients with end-stage heart disease or poor myocardial function after cardiac surgery. It is a pneumatic and diaphragm-type VAD and its stroke volume is 90 cc. The upper housing and diaphragm is made of a segmented polyurethane and the lower back plate is made of a polycarbonate. Two Carbomedics$^R$ mechanical valves are used as inlet and outlet valves. It was tested in vitro and the cardiac output of the VAD was 7 L/min at a heart rate of 70 bpm. The line pressure from a pressure transducer inserted in the pneumatic line was recorded and compared with the ideal pressure tracing.

• Journal of the Korea Safety Management & Science
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• v.16 no.2
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• pp.211-216
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• 2014

Using a high-rise building water piping after hydrostatic test of the reliability of the leak to be completed if the pressure is maintained until the leak is not commercially available considered. Due to the nature of high-rise buildings and the construction period will take several years from the lower levels of use of the water supply and fire fighting water pipe construction is in progress, the order of which I do most of the first pipe to the construction and more than three years. So kind of riser pipe is complete, install the valve in the basement by installing an automatic pump to maintain a constant pressure after hydrostatic test and after each floor plumbing piping is complete, the progress of the hydrostatic test without undergoing a separate branch pipe the valve is opened automatically when the number of the pressing pressure of the structure. I kind of do and keep working pressure of pipe until the completion of the construction work to keep the damage to human error when it is intended to prepare. In winter, the frost protection and an alternative to drainage water pipe is damaged or deformed, even if unaware of the finishing work to the building, the use of the damage caused by a leak in a after construction of finish work to be expected. Alternative to reduce this damage if the pressure test without fear of freezing to help maintain long-term commercial pressures may be considered.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.1-10
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• 2020

The pneumatic control circuit is an important basic element that constitutes factory automation in the era of the 4th Industrial Revolution, and the ability to design and fabricate pneumatic control circuit at the university level is one of the most important educational courses. In this study, it introduced collaborative learning by group, and capstone design technique applied to the subject of design and fabricate of pneumatic control circuit. In addition, it intends to contribute to the innovation of practical engineering education by examining the learning achievement of students. It was investigated analytical skill differences by applying cooperative learning to the experimental group and by applying traditional lecture methods to the comparison group. The experimental group that conducted cooperative learning showed higher academic ability than the comparison group that conducted only traditional lectures, and the t-test results of the significant level p<0.05 also confirmed that there were significant differences between the two groups. It was also responded 13 survey questions in four experimental groups and analyzed the results, showing a high satisfaction level of 4.731 on average. Through this study the design and fabrication of the pneumatic control circuit is more effective in improving students' learning achievement when applying the capstone design technique than when operating as a normal subject and expected to use as a basic material for the development of the curriculum of Capstone design in the future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1169-1174
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• 2013

Most products are indeed governed by multiple failure modes. However, there are few cases in which reliability analysis applies to only one failure mode at a time. Furthermore, reliability data do not include information about failure modes, or the reliability analysis is performed using a representative failure mode. The Weibull shape parameter for failure modes is more important than one for products in the reliability qualification test. This paper presents reliability analysis methods for a mechanical component with multiple failure modes. These methods include the competing failure modes (CFM) method and the mixed Weibull method. Pneumatic cylinder test data with three failure modes are presented to estimate the shape parameter for each separate failure mode. In addition, reliability measures (B10 life, characteristic life) of the pneumatic cylinder considering three failure modes were compared with those assuming a single failure mode.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1784-1787
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• 2005

In this paper, proportional modulator which controls the second pressure of the pneumatic system was studied and proportional operating of modulator was gotten by two digital valves that have a fast dynamic characteristics and were controlled by PWM operating method. In order to more precision pressure control, this modulator consist of not only high speed two digital valves but also pressure sensor, measurement equipment and controller having a microprocessing function. In this study, for the development of the new proportional modulator, various research such as PWM control method, test equipment manufacturing, testing and evaluation were accomplished.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.776-784
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• 2002

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1215-1220
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• 2008

The aim of this paper is to perform a finite element analysis that will have the ability to predict the seal performance characteristics, such as deformation, contact load and friction and also is to provide a means of potential seal designs, which can reduce the time and cost of designing the performance of the seal. The material property tests of elastomer seal are performed to obtain the hyperelastic properties and The Mooney-Rivlin constants are determined from these test results. A 2D modelling of the seal cross section is performed to simulate the contact behavior between the seal on the piston and the cylinder bore under operation conditions. The deformation behavior, contact load and friction of an elastomer seal is analyzed by a finite element method which performs three analytic phases of interference fit, the variations of pneumatic pressure and piston movement under the operational conditions.