• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.2
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• pp.1-6
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• 2006

The pressure regulator which is used for controlling the reducing pressure in the piezoelectrically driven pneumatic valve has been studied. The pneumatic valve of this study object is 2-stage type and consists of a piezoelectric actuator, a controller, a poppet valve and a pressure regulator. Nominal flow of 50 lpm, maximum operating pressure of 0.9MPa and frequency characteristic of 10Hz and over are required in this pneumatic valve, but the pressure regulator is needed because piezoelectric actuator has no ability to control the pressure of 0.9MPa directly. In this study, bimorph type PZT actuator of $25.2mm(L){\times}7.2mm(W){\times}0.5mm(H)$ with constant of $-220{\times}10-12$ CN-1 was proposed and investigated. Maximum operating force of 0.052 N and maximum displacement of $63{\mu}m$ were gotten from the fabricated PZT actuator. From the analysis results, the orifice diameter of 0.6mm for a piezoelectric actuator was derived and then the pressure regulator which can be operated under 0.15 MPa easily was designed and manufactured. Performance and effects of design parameters were simulated by the Simulink of Matlab software, and it was confirmed that the performance characteristics of manufactured pressure regulator are superior in the common use pressure range of 0.5 MPa to 0.7 MPa. The results show that the proposed pressure regulator is suitable for the pneumatic valve with a PZT actuator.

• Journal of Drive and Control
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• v.14 no.3
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• pp.32-39
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• 2017

In this study, a mathematical model of the pneumatic part in a gas blow-down system is proposed. The mathematical model consists of four major parts: pressure vessel, reservoir, pressure regulator and pipe-line. To ensure accuracy in long-time simulations, heat transfer between gas and pressure vessel is considered. The model is validated by comparing simulation results with experimental data. Experiments are conducted on the ground, where free convection can be assumed. Simulation results indicate the proposed model can accurately describe behavior of a gas blow-down system. Therefore, it may be used for design and analysis of similar systems with a slight modification.

• Journal of Drive and Control
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• v.16 no.2
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• pp.66-71
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• 2019

In this study, flow analysis and dehumidification experiments were performed on hollow fiber membrane module to confirm the dehumidification characteristics for its different configurations. The CFD for the three different models was conducted using $30^{\circ}C$ temperature and 30%RH inlet humidity for quantitative analysis. Each model has different shape parameters i.e. the number of baffles. Comparison between flow analysis results and dehumidification experiment results revealed a percentage error of about 5%. The difference in relative humidity between the inlet and outlet for each model was calculated using flow analysis data. It was established that the difference in relative humidity of the inlet and outlet for the refined model with three baffles was highest among the three modeled modules of hollow fiber membrane module, i.e. around 9%.

• Journal of Drive and Control
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• v.14 no.4
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• pp.1-8
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• 2017

The Down-the-Hole hammer is one of the pneumatic drill equipment used for grinding, drilling, and mining. One the advantages of which is that a reduction work efficiency at deep site are relatively small compared to other drilling methods. Due to the large vibration in the underground area, it is difficult to measure the performance of the hammer, and hammer testing requires substantial production cost and operating expenses so research on the development of the hammer is insufficient. Therefore, this study has developed a dynamic simulation model that apprehends the operating principles of an 8-inch DTH hammer and calculates performance data such as performance impact force, piston speed, and BPM. By using the simulation model, design factors related to strike force and BPM were selected, and the influence of each design factors on performance was analyzed through ANOVA analysis. As a result, be the most important for BPM and the strike force are position of upper port that push the piston in the direction of the bit and in BPM, the size of the empty space between the bits and the piston is the second most important design factor.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.87-91
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• 2015

For construction projects it is imperative that site management gives the highest priority to planning safe site evacuation for all foreseeable emergencies, including earthquakes and typhoons which are often experienced in Japan. This is especially important and even more critical for high risk projects involving underground works, such as Tunneling & Pneumatic Caissons. Based on the safety regulation of underground works, a back-up power supply system must be provided during the construction period at all times. Often, fluorescent lamps with re-chargeable batteries are provided for infrequent emergency cases, however these have a questionable useable life span and thus need careful maintenance and periodical replacement. In this paper we focused on using the phosphorescence materials to indicate the evacuation direction. As a result, it was confirmed that the phosphorescence materials were considered useful in reducing panic and facilitating a controlled evacuation in the event of a total black-out due to power failure.

• Journal of Drive and Control
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• v.18 no.4
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• pp.77-83
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• 2021

With the progress in virtual reality technology, various virtual objects can be displayed using head-mounted displays (HMD). However, force feedback sensations such as pushing against a virtual object are not possible with an HMD only. Focusing on force feedback, desktop-type devices are generally used, but the user cannot move in a virtual space because such devices are fixed on a desk. With a wearable force feedback device, users can move around while experiencing force feedback. Therefore, the authors have developed a wearable force feedback device using a magnetorheological fluid clutch and pneumatic rubber artificial muscle, aiming at presenting the elasticity, friction, and viscosity of an object. To date, we have developed a wearable four-degree-of-freedom (4-DOF) force feedback device and have quantitatively evaluated that it can present commanded elastic, frictional, and viscous forces to the end effector. However, sensory evaluation with a human has not been performed. In this paper, therefore, we conduct a sensory evaluation of the proposed method. In the experiment, frictional and viscous forces are rendered in a virtual space using a 4-DOF force feedback device. Subjects are asked to answer questions on a 1- to 7-point scale, from 1 (not at all) to 4 (neither) to 7 (strongly). The Wilcoxon signed rank test was used for all data, and answer 4 (neither) was used as compared standard data. The experimental results confirmed that the user could feel the presence or absence of viscous and frictional forces. However, the magnitude of those forces was not sensed correctly.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.160-170
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• 2006

If hydraulic pump controlled by mechanical type regulator has more than one control function, the construction of regulator will be very complicated and control performance falls drastically. It is difficult to have more than one control function for hydraulic pump controlled by electronic type hydraulic valve due to the inconsistency of controllers. This paper proposes a multi-function control technique which controls continuously flow, pressure and power by using EPPR(Electronic Proportional Pressure Reducing) valve in swash plate type axial piston pump. Nonlinear mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. A reaction spring is installed in servo cylinder to secure the stability of the control system. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.

• Journal of Drive and Control
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• v.16 no.4
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• pp.65-73
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• 2019

In this study, flow analysis and fluid-solid interaction analysis were conducted on a hollow fiber membrane module used for analysis of dehumidification characteristics. To ensure the reliability of the flow analysis results, the dehumidification experiment was performed under the temperature of 30℃ and relative humidity of 30% RH. The results of the dehumidification experiments were compared with the flow analysis results. The results of dehumidification experiments and flow analysis had a difference of approximately 5%. A 1-Way fluid-solid interaction analysis with various materials was conducted. From the results, it was found that the baffle with the largest shape deformation (polyethylene material) was subjected to 2-way fluid-solid interaction. The analysis of fluid flow and dehumidification characteristics were analyzed according to the shape deformation of the baffle.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.89-94
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• 2017

Pneumatic systems are widely applied in various industry because it have a many advantage(low cost, high safety, etc.). Air compressors supply the working fluid to the pneumatic systems and consume a lot of electrical energy at the manufacturing site. The one of the suggested idea is to reduce the energy consumption by reducing the suction temperature of the air compressor and increasing the discharge flow rate. In this paper, the discharge flow rate and air power of the positive displacement type air compressor is simulated by changing the temperature of suction air and the relationship between the suction air temperature and the performance variation of the air compressor is analyzed. As a result, we know that as the suction temperature of air is lowered, the discharge mass flow-rate is increased, but the specific enthalpy is reduced rather than increased, which means that the power of the discharged air is not greatly increased even if lower the suction air temperature.

• Journal of Drive and Control
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• v.16 no.2
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• pp.51-58
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• 2019

In this study, flow analysis and dehumidification experiment were conducted on hollow fiber membrane module to determine the dehumidification characteristics of its various configurations. A quantitative analysis of the CFD for four different models with a temperature of $30^{\circ}C$ and 30%RH inlet humidity was conducted. Each model has different shape parameters i.e. the number of hollow fiber membranes and the presence or absence of baffles. After comparison between the flow analysis results and dehumidification experiment results, the percentage error was found to be approximately 2%. The moisture removal rate for each model was calculated using flow analysis data. It was found that the moisture removal rate of refined model with three baffles and eight hollow fiber membranes was highest among the four modeled modules of hollow fiber membrane one, i.e. about 60%.