• Journal of the Korean Society for Precision Engineering
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• v.31 no.1
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• pp.51-57
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• 2014

This paper presents a synchronizing adaptive feedforward control for clamping servomechanism of injection molding machines. Based on MBS, virtual design model has been developed for a direct forcing clamping mechanism. A synchronizing controller is designed and combined with adaptive feedforward control to accommodate mismatches between the real plant and the linear plant model used. From tracking control simulations, it is shown that significant reduction in position tracking error is achieved through the use of proposed control scheme.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.194-197
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• 2004

In the tube hydroforming process, a tube is placed into the die cavity and the ends of the tube are sealed by fixing the axial cylinder piston into the ends. Then the tube is pressurized with a hydraulic fluid and simultaneously the axial cylinders move to feed the material into the expansion zone. Therefore, the quantitative relationship between process parameters such as internal pressure and feeding amount and hydroformabillity, is hard to establish because of their high complexity and many unknown factors. In this study, the empirical and the quantitative relationship between process parameters and hydroformabillity are analyzed by fuzzy rules. Fuzzy expert system is an advanced expert system which uses fuzzy rule and approximate reasoning. Many process parameters are converted to the quantitative relationship by use of approximate reasoning of fuzzy expert system. The comparison between experimentally measured hydroformabillity from hydroforming experiments and the predicted values by fuzzy expert system shows a good agreement.

• Journal of Drive and Control
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• v.16 no.4
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• pp.9-15
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• 2019

Bucket trajectory is crucial regarding precision work with an excavator. In general, the bucket trajectory deviation is determined by the machining deviation of the frame, driving deviation of the driving hydraulic cylinder, clearance in the joints, and deformation of the structure. This paper investigated the relationship between the respective clearance in joints and the trajectory deviation of the bucket at the finishing work of the ditching for a 20-ton excavator. As a result, the larger the clearance, the larger deviation is increased at trajectory. However, it was found that the deviation of the rotation angle and displacement of the bucket was limited and the size of clearance does not affect closely on the contact angle of the pin shaft.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.465-470
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• 2006

An experimental investigation is carried out to study 2-phase vertically upward hydraulic transport of solid particles by water and non-Newtonian fluids in a slim hole concentric annulus with rotation of the inner cylinder. 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 fluid velocities varied from 0.2 m/s to 3.0 m/s. Pressure drops and average flow rate and particle rising velocity are measured. For both water and 0.2% CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.51.4-51
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• 2001

In order to comprise a basic closed-loop control system for a field robot it is necessary to detect the piston rod stroke of a hydraulic cylinder. There are mary conventional type sensors which can detect the displacement of cylinders. However, they cannot reveal the original performance normally or the cannot be applied at all where the operating circumstance of cylinders is beyond specifications of sensors. In this paper, an exclusive method for detecting the piston rod stroke is suggested, which adopts a remote detecting technique using optical fiber sensors. Several experiments using the prototype are executed for verifying the effectiveness of the suggested method and the possibility of the accurate detection of stroke.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.159-163
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• 2003

In recent days, as the efficiency of electronic home applications become higher, that of the driving AC motor become higher. On this reason, the demand fir high capacity coil firming machine is increasing. Since the coil forming is not simply related with the only capacity of hydraulic cylinder, the development of a newer coil firming machine which has new filming mechanism new driving method, new filming tool, and new specification is required. In this paper, the virtual prototype which have new mechanism is developed. This prototype is tested and experimented on PC with the same condition as actual. The results from the virtual experiment is applied to the actual design process.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.109-114
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• 2008

The solenoid valve of ABS hydraulic modulator is a two directional on-off valve and is controlled by around 100Hz on-off control. When the on-off valve is switched from open state to closed state, there are braking force deterioration, noise and vibration due to surge pressure in the wheel cylinder. In this study, identifies surge pressure in the braking process of ABS, and investigates the way to reduce the phenomenon. To reduce the surge pressure, PWM(Pulse Width Modulation) control with high frequency of 20kHz was attempted. In conclusion, by using the results of this study for the pressure surge prediction, we could expect enhancement of braking performance in ABS.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.56-63
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• 2008

Many advanced nations have been developing the next generation logistic systems to effectively deal with gradually increased logistic flows over the world. Particularly, dual mode trailer(DMT) systems are significantly focused as a new alternative transportation which basically provides integrating of the land and railroad services. This paper presents new driving mechanism for DMT systems using the hydraulic pressure cylinder systems. Such is mechanically composed of supporting and rotating parts independently, which are mostly important for whole system performance. We analyze feasible operational problem occurred in driving mechanism from the conventional DMT systems and compare our proposed deign specification with the Modalohr DMT system to demonstrate its reliability and practicability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.982-986
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• 2000

Perpendicular guideway mechanism has a different behavior with horizontal guideway mechanism due to the slider weight. So, to decrease its weight effect, counter balances such as weight type and hydraulic cylinder type are used. But it can also make another motion behavior by weight rate of slider and counter balance, its connected position. Therefore, it is necessary to find design parameters and analyze their effect. This paper dealt with the optimal design of perpendicular guideway mechanism. For analysis, the theoretic model as same as real machine tool and sib plate to adjust the clearance was used. Rotational angle and displacement of slider, pressure distribution, friction distribution were calculated. Stick slip, intermittent motion of slider according to friction change was adapted to the perpendicular guideway mechanism.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.687-692
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• 1990

The purpose of this study is ID form the required force for measurements of the performances of the equipments or testpieces. For the generation of the required force, ft difference of pressures in each chamber of the hydraulic cylinder was controlled and Variable Structure Control theory was adopted to control it. Besides, observers -Luenberger Observer and nonlinear Variable Structure Observer - were designed to estimate the derivative of the load pressure which is necessary ID determine the sliding surface in VSC theory. As a consequence of the computer simulation, it was shown that VSC had better performance than classical control theory(P, PD control) and VSO performed better than the Luenberger Observer at the load pressure control.