• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.58-67
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• 1998

A sectional analysis of sheet metal forming process with an arbitrary tool shape is proposed in the present work. To improve the numerical convergence in the conventional membrane sectional analysis, the Bending Energy Augmented Membrane (BEAM) elements had been developed. The BEAM elements particularly improve the stability and convergence of the finite element method for the case of deep drawing. In this work, the FERGUBON spline (C$^2$-continuous) was used to fit the deformed mesh to smooth the given curves and calculate the local curvature of the deformed sheet. The fittings of the deformed sheet and tool surface profile ensure the stability and the convergence of the finite element analysis of highly nonlinear stamping processes. A center floor section and front fender section are analyzed to show the accuracy and robustness of the approach. The results obtained by the proposed approach are compared with the available experimental data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.3-6
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• 2001

The present work concerns rapid tooling technology based on three-dimensional CAD/CAM. Two types of tooling processes have been introduced : the quick delivery molding(QDM) process and the rapid tooling(RT) process using a rapid prototyping system. Both processes are based on three-dimensional CAD/CAM technology and realize a paperless manufacturing system with a high efficiency. The proposed approach has been applied to the product development for various electrical parts, and the final delivery has been reduced as compared with the traditional approach.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.459-464
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• 2001

A reliable tool wear monitoring technique is the one of important aspects for achieving an integrated and self-adjusting manufacturing system. In this paper, a tool wear estimation approach for turning is proposed. This approach uses the model of cutting force, spindle displacement and their relation. A series of experiments were conducted by designing experimental techniques to determine the relationship between flank wear and cutting force coefficient as well as cutting parameters such as cutting speed, depth of cut and feed. The proposed model performance has shown that the spindle displacement model predicts tool wear with high accuracy and spindle displacement signal is possible to replace cutting force signal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.506-511
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• 1996

The performance evaluation of flexible manufacturing systems or cells at the stages of design and planning is one of important issues in manufacturing. For that reason, Guo has presented an approachbased on moment generating function and generalized stochastic PetriNets for performance analysis. In this paper, Buo's approach is extended tothe cases of flexible manufacturing cell including one machining center with a local buffer, AS/RS(Automatic Storage and Retrieval System), set-up station and AGV(Automated Guided Vehicle). Then the performance measures from this approach is compared with simulation. The major advantage ofthis method over existing performance evaluation methods is the ability to compute analytic solutions for performance measures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.689-693
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• 1996

This paper was performed on the automatic selection of cutting condition on multispindle machine. the several mathematical relationships were formulated for simulataneous selection of machining parameters and tool changing scheme. In this research we used two step generative approach; step 1 is mathematical modeling for the selection of optimal cutting conditions and the other is GMDH-TYPE modeling to find prediction equation of system performance. thus in this paper, mathematical machining models combined with a heuristic GMDH-TYPE modeling to estimate the system performance, these models are developed computer programs for practical application and it was shown that the proposed approach has a good potential and offers a valuable tools to performance evaluation for metal cutting system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.321-324
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• 2003

There are two steps to solve the self-collision avoidance problems for redundant manipulators. First, all links are regarded as cylinders. and then the collisions should be checked among all pairs of the links. Between two cylinders. we can get the collision information derived from the concept or configuration space obstacle in real time. Therefore. it is possible to detect the links where collisions are likely in real time by setting the risk radius which is larger than actual radius. Second. the configuration control points (CCP) should be placed at the ends of the detected links. A cost function is the sum of the distances between the CCPs. To maximize the cost function means the links go far away each other without self-collisions.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.3
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• pp.51-55
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• 2006

An adaptive tracking controller is presented for the vibration reduction of flexible manipulator employed in hazardous area by combining input shaping technique with sliding-mode control. The combined approach appears to be robust in the presence of severe disturbance and unknown parameter which will be estimated by least-square method in real time. In a maneuver strategy, it is found that a hybrid trajectory with a combination of low frequency mode and rigid-body mode results in better performance and is more efficient than the traditional rigid body trajectory alone which many researchers have employed. The feasibility of the adaptive tracking control approach is demonstrated by applying it to the simplified model of robot system. For the applications of the proposed technique to realistic systems, several requirements are discussed such as control stability and large system order resulted from finite element modeling.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.3
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• pp.66-71
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• 2006

Some wheelchair users with neuromuscular disorders experience involuntary extensor thrusts, which may cause injuries via impact with the wheelchair, cause the user to slide out of the wheelchair seat, and damage the wheelchair. Knowledge of the human-generated forces during an extensor thrust is of great importance in devising safer, more comfortable wheelchairs. This paper presents an efficient method for identifying human-generated forces during an extensor thrust. We used an inverse dynamic approach with a three-link human body model and a system for measuring human body motion. We developed an experimental system that determines the angular motion of each human body segment and the force at the footrest, which was used to overcome the mathematical indeterminacy of the problem. The proposed method was validated experimentally, illustrating the force-identification process during an extensor thrust.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1390-1393
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• 2003

Work factor approach is conveniently used in metal fracture mechanics to determine fracture toughness from a single fracture test. In this work, we investigated the applicability of the work factor approach in order to determine fracture toughness of thick graphite/epoxy composites in the hydrostatic pressure environment from a single fracture test. The effect of hydrostatic pressure on the elastic work factor was studied, The stacking sequence used was multi-directional, [0$^{\circ}$/${\pm}$45$^{\circ}$/90$^{\circ}$]. The hydrostatic pressures applied were 0.1 MPa, 100 MPa, 200 MPa, and 300 MPa. The results showed that the elastic work factor was not affected by the hydrostatic pressure, The elastic work factor decreased in a linear fashion with crack length.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.235-239
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• 1992

The paper describes an approach for estimating unsteady flow rate through oil hydraulic pipelines and components in real time. Recently we have proposed following three unsteady flow rate measurement approaches; RIFM, QIFM and TPFM, in which hydraulic pipeline dynamics are made use of. In this paper, we firstly propose new approaches, i.e, an interpolation and an extrapolation methods in combination with RIFM and TPFM. In the interpolation method, unsteady flow rate at the arbitrary internal location along the pipeline between two points for measuring the two point pressure can be estimated. In this paper, the accuracy and dynamic response of interpolation method are mainly experimentally investigated in detail.