• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.8-14
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• 2008

Basic characteristics of wheel brake accumulator for aircraft is studied. Wheel brake accumulator maintains the braking pressure for parking mode, and also it supplies the hydraulic pressure to the wheel brake system for emergency mode. The design requirements of wheel brake accumulator are analyzed and the initial sizing is conducted. A wheel brake accumulator consists of a cylinder and a brake control module, and the basic configuration and detail components are presented. Again, structural static analysis of vessel is performed with NASTARN/PATRAN for preliminary design.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.146-154
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• 1997

Solenoid-folw control type ABS is used with a 'dump and reapply' pressure control arrangement instead of using 2/2 (normal open/close) solenoid valves in convensional systems(sol. -sol. control type), a flow control valve is used which replaces the (no) inlet valve. The flow control valve controls fluid flow providing a nearly constant reapply rate( .theta. ) after the dump plase of ABS operation. In this study, to investigate a characteristics of brake pressure by PWM control, test rig was consisted of ABS hydraulic modulator, digital controller, pneumatic power supply and brake master cylinder. For comparison with experi- mental results, system modelling and computer simulation were performed. As a result, experiment results showed fairly agreement with the simulation. Also, it is shown that the pressure gradient (tan .theta. ) is affected by pressure, frequency, duty ratio and expressed with an exponential funtion.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.131-137
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• 2015

Home Entertainment system is recently being offered by Home Theater & Smart TV with contents service. Also, console game is being played in the media like in TV. The usage of 4D as the main technology in entertainment industry has mostly been limited in Theme Park, Amuse Park, Theater, and contents for Movie and Animation. Some simulation systems for game has been developed but they were made mostly by using electric or hydraulic motion system which cause high power consumption and have a restriction of place for install. The paper is attempted to build Home Entertainment system which makes users feel realistic contents by developing 4D systems for Home Entertainment rather than before. 4D control S/W in which user can insert and edit 4D effects on contents of all areas such as game, movie, and broadcasting is developed. Also, built-in pneumatic cylinder in 4D system which can be easily controlled and managed in home is developed.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.4
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• pp.1-7
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• 2007

Flow rate is one of the important variables for precise motion control and detection of the faults and fluid loss in many hydraulic components and systems. But in many cases, it is not easy to measure it directly. The orifice area of a servo valve by which the fluid flows is one of key factors to monitor the flow rate. In this paper, we have constructed an estimation algorithm for the effective orifice area by using the model of a servo valve cylinder control system and Kalman filter algorithm. Without geometry information about the servo valve, it is shown that the effective orifice area can be estimated by using only displacement and pressure data corrupted with noise. And the effect of the biased sensor data and system parameter errors on the estimation results are discussed. The paper reveals that sensor calibration is important in accurate estimation and plausible parameter data such as oil bulk modulus and actuator volume are acceptable for the estimation without any error. The estimation algorithm can be used as an useful tool for detecting leakage, monitoring malfunction and/or degradation of the system performance.

• Journal of Practical Engineering Education
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• v.9 no.2
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• pp.119-124
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• 2017

In injection molding process, the runner system of the mold is a flow path for filling the cavity of the molded part during the advance of the screw by the force of the hydraulic cylinder, which involves the filling and packing process of the molten resin. Thus, the sprue, runner and gate greatly affect the appearance of the molded part, the physical properties of the resin, the dimensional accuracy and the molding cycle etc. Feed systems with incorrect runner and gate designs cause various molding defects, So it is important to maintain the optimum runner balance to prevent these defects. In order to improve the knowledge of practical mold technology, which is applied to the manufacturers of injection molds, a training model of the mold technology process is presented based on the technical guidance on the technical difficulties.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.737-744
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• 2021

An investigation is conducted to study a solid-liquid mixture vertically upward hydraulic transport of solid particles by non-Newtonian fluids in the Mud system. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular velocities varied from 0.4 m/s to 1.2 m/s. The mud systems which were utilized included aqueous solution of sodium carboxymethyl cellulose (CMC) solutions. Main parameters considered in the study were inner-pipe rotary speed, fluid flow regime and particle injection rate. Solid volumetric concentration and pressure drops were measured for the various parameters such as inclination angle, flow rate, and rotational speed of inner cylinder.

• Journal of Drive and Control
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• v.11 no.4
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• pp.53-60
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• 2014

This paper proposes a control scheme to reduce the power consumption of a variable displacement swash-plate type piston pump supplying oil to a valve-controlled hydraulic cylinder at constant pressure. Whenever flow rate demand was absent, the swash plate angle and the pump speed were changed to the minimum values required to compensate for the internal leakage flow. In response to command signals, the pump speed was changed in proportion to the absolute mean value of the speed component for position commands. At the same time, a pressure regulator was activated to maintain constant system pressure by precisely adjusting the pump speed with the swash plate angle fixed at the maximum. The conventional system consisting of a pressure-compensated variable displacement type pump is driven at a constant speed of 1,800rpm. By comparison, computer simulation and experimental results showed that idling power at stand-by status could be reduced by up to 70% by reducing the pump speed from 1,800rpm to 300rpm and the swash plate angle to the minimum.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.18-27
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• 2019

The Advanced Power Reactor 1400 (APR1400) Steam Generator (SG) uses alloy 690 as a tube material and SA-508 Grade 3 Class 1 as a tubesheet material to form tube-to-tubesheet joint through hydraulic expansion process. In this paper, the residual stresses in the SG tube-to-tubesheet contact area was investigated by applying Model-Based System Engineering (MBSE) methodology and the V-model. The use of MBSE transform system description into diagrams which clearly describe the logical interaction between functions hence minimizes the risk of ambiguity. A theoretical and Finite Element Methodology (FEM) was used to assess and compare the residual stresses in the tube-to-tubesheet contact area. Additionally, the axial strength of the tube to tubesheet joint based on the pull-out force against the contact joint force was evaluated and recommended optimum autofrettage pressure to minimize residual stresses in the transition zone given. A single U-tube hole and tubesheet with ligament thickness was taken as a single cylinder and plane strain condition was assumed. An iterative method was used in FEM simulation to find the limit autofrettage pressure at which pull-out force and contact force are of the same magnitude. The joint contact force was estimated to be 20 times more than the pull-out force and the limit autofrettage pressure was estimated to be 141.85MPa.

• Journal of Drive and Control
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• v.19 no.2
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• pp.11-16
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• 2022

It is important to measure the excavator's work productivity that estimates the bucket's payloads on a process. If the bucket isn't filled at every working cycle, the excavator's operator has to drive the machine more to achieve his work quota. If bucket is filled over with the load, the other way around, the transferred object has to spread out on the workplace. That causes additional work to clean the site. This paper proposes a method that can estimate the bucket's payload to improve the excavator's work productivity. This method assumes that the excavator is a lumped mass system. And it uses a 3 points angle (boom link, arm link, swing) and 2 points pressure (boom cylinder's input port and output port) of measurable data. Depending on assumptions, the bucket's payload can be calculated by the payload's motion equation. And this suggested method can be verified by simple experiments.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.81-89
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• 2009

Dancer systems are typical equipment for attenuation of tension disturbances. Lately, demands for high speed roll-to-roll machines are rising but it is prior to attenuate the tension variation on the web entering into the printing zone to achieve the speed increment. Maintaining a constant tension before the first printing cylinder is the key of high speed, high quality printing. Dancer has been researched in two ways, whether it is controlled or not. The first one is active dancer and the other one is passive dancer. In the active dancer, a position of idle roll of dancer is measured and the roll is moved by external hydraulic cylinder to control tension disturbances. While the passive one composed with spring, damper and idle roll has no external actuator to position the idle roll. The tension disturbance causes movement of dancer roll and the displacement of the roll regulates the tension variation. On the other hand a composite type of dancer is applied for roll-to-roll printing machines. It has same apparatus as passive dancer. The displacement of roll is measured and front(or rear) driven roller is controlled to position the roll. In this paper, it is presented an analysis of pendulum dancer including position feedback PI control and logic for PI gain tuning in roll-to-roll machines. Pole-zero map and root locus with varying system parameters gives a design method for control of the dancer.