• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.925-936
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• 2003

The manipulability analysis of the parallel-type rolling mill proposed in Hong et al. [1] is re-visited. The parallel rolling mill uses two Stewart platforms in opposite direction for the generation of 6 degree-of-freedom motions of each roll. The objective of this new parallel rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of rolls, and tension of the strip. New forward/inverse kinematics problems, in contrast with [1], are formulated. The forward kinematics problem is defined as the problem of finding the roll-gap and the pair-crossing angle of two work rolls for given lengths of twelve legs. On the other hand, the inverse kinematics problem is defined as the problem of finding the lengths of twelve legs when the roll-gap, the pair-crossing angle, and the position and orientation of one work roll are given. The method of manipulability analysis used in this paper follows the spirit of [1]. But, because the rolling force and moment exerted from both upper and lower rolls have been included in the manipulability analysis, more accurate results than the use of a single platform can be achieved. Two. kinematic parameters, the radius of the base and the angle between two neighboring joints, are optimally designed by maximizing the global manipulability measure in the entire workspace.

• 한국정밀공학회지
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• 제29권1호
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• pp.64-71
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• 2012

In this paper, a parallel manipulator is comprised of two sliders and four links. Sliders execute a linear reciprocating motion depending on parallel guides and make the connected links rotate. A couple of links connected by sliders do coupling motion. The end-effector called a link tip has orientation angle. Through the kinematics analysis of this manipulator, we found displacement, velocity and acceleration using direct and inverse kinematics. We used equations that derived from this analysis and determined five constraint conditions. These conditions had much to do with rotation states of links, the relative relation of link length and coupling motion state. To verify those, we suggest a new algorithm regarding constraint conditions of a manipulator. With the result which performed the algorithm, we found out that operation range of coupled links was limited by relative relation of link length and that manipulator was not able to carry out a series of link motion, in case of being the link vertical between two parallel guides.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2007-2015
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• 2005

A large-scale analysis to evaluate complex material and structural behaviors is one of interesting topic in diverse engineering and scientific fields. Also, the utilization of massively parallel processors has been a recent trend of high performance computing. The objective of this paper is to introduce a parallel process system which consists of general purpose finite element analysis solver as well as parallelized PC cluster. The later was constructed using eight processing elements and the former was developed adopting both hierarchical domain decomposition method and balancing domain decomposition method. Then, to verify the efficiency of the established system, it was applied for structural analysis of steam generator in nuclear power plant. Since the prototypal evaluation results agreed well to the corresponding reference solutions it is believed that, after reinforcement of PC cluster by increasing number of processing elements, the promising parallel process system can be utilized as a useful tool for advanced structural integrity evaluation.

• 동력기계공학회지
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• 제17권3호
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• pp.50-56
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• 2013

The analysis of performance characteristics was carried out in the plate type evaporator with counter and parallel flow. To investigate performance of evaporator with water inlet temperature and refrigerant mass flow rate were changed. As a result, when the inlet temperature of water is $8^{\circ}C$, capacity of parallel flow evaporator higher than counter flow is 0.35%. But as the inlet temperature of water rises from $8^{\circ}C$ to $16^{\circ}C$, capacity of counter flow type evaporator higher than parallel flow type is 0.12%, 0.27%, 1.1%, 1.6%, respectively. The findings showed that counter flow type evaporator has a larger capacity than those that were parallel flow type evaporator. As the refrigerant mass flow rate rises, capacity and pressure drop increases in the counter and parallel flow type evaporator.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1215-1230
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• 2000

Parallel Approaches using Cray T3E which is NIPP (Massively Parallel Processors) machine are presented for the efficient computation of the finite element analysis of 3-D shape rolling processes. D omain decomposition method coupled with parallel linear equation solver is used. Domain decomposition is applied for obtaining element tangent stifffiess matrices and residual vectors. Direct and iterative parallel algorithms are used for solving the linear equations. Direct algorithm is_parallel version of direct banded matrix solver. For iterative algorithms, the well-known preconditioned conjugate gradient solver with Jacobi preconditioner is also employed. Moreover a new effective iterative scheme with block inverse matrix preconditioner, which is named by present authors, is presented and its results are compared with the one using Jacobi preconditioner. PVM and MPI are used for message passing and synchronization between processors. The performance and efficiency of each algorithm is discussed and comparisons are made among different algorithms.

• Advances in robotics research
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• 제1권2호
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• pp.141-154
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• 2014

Redundant parallel manipulators have some advantages over the nonredundant parallel manipulators. It is important to determine how many additional branches should be introduced. This paper studies whether one or two additional branches should be added to a 3-DOF parallel manipulator by comparing the flexible deformation of a 3-DOF parallel manipulator with one additional branch and that with two additional branches. The kinematic and dynamic models of the redundant parallel manipulator are derived and the flexible deformation is investigated. The flexible deformation of the manipulators with one additional branch and two branches is simulated and compared. This paper is helpful for designers to design a redundantly actuated parallel manipulator.

• Journal of Multimedia Information System
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• 제4권4호
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• pp.219-224
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• 2017

This paper is to introduce an application of face recognition algorithm in parallel. We have experiments of 25 images with different motions and simulated the image recognitions; grouping of the image vectors, image normalization, calculating average image vectors, etc. We also discuss an analysis of the related eigen-image vectors and a parallel algorithm. To develop the parallel algorithm, we propose a new type of initial matrices for eigenvalue problem. If A is a symmetric matrix, initial matrices for eigen value problem are investigated: the "optimal" one, which minimize ${\parallel}C-A{\parallel}_F$ and the "super optimal", which minimize ${\parallel}I-C^{-1}A{\parallel}_F$. In this paper, we present a general new approach to the design of an initial matrices to solving eigenvalue problem based on the new optimal investigating C with preserving the characteristic of the given matrix A. Fast all resulting can be inverted via fast transform algorithms with O(N log N) operations.

• 제어로봇시스템학회논문지
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• 제3권5호
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• pp.482-489
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• 1997

This paper presents the analysis of the kinematics and dynamics of redundant parallel manipulators, and provides design guides for advanced parallel mainpulators with high performance. Three types of redundancies are considered which include the redundancies in serial chain, joint actuation, and parallelism. First, the kinematic and dynamic models of a redundant parallel manipulator are obtained in both joint and Cartesian spaces, and the kinematic and dynamic manipulabilities are defined for the performance evaluation. The effects of the three types of redundancies on the kinematic and dynamic performance of a parallel manipulator are then analyzed and compared, providing a set of guides for the design of advanced parallel manipulators. Finally, the simulation results using planer parallel manipulators are given.

• ETRI Journal
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• 제31권4호
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• pp.387-392
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• 2009

This paper introduces a novel parallel shift operator finite-difference time-domain (SO-FDTD) method for plasma in the dispersive media. We calculate the interaction between the electromagnetic wave of various frequencies and non-magnetized plasma by using the parallel SO-FDTD method. Then, we compare the results，which are calculated with serial and parallel SO-FDTD executions to obtain the speedup ratio and validate the parallel execution. We conclude that the parallel SO method has almost the same precision as the serial SO method, while the parallel approach expands the scope of memory and reduces the CPU time.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권4호
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• pp.154-160
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• 2003

The switched reluctance motor(SRM) has a considerable potential for industrial applications because of its high reliability as a result of the absence of rotor windings. In some applications with SRM, a parallel switching strategy is often used for cost saving, increasing of current capacity and system reliability. This paper proposes a new parallel switching strategy of SRM using parallel winding. While conventional parallel switching devices are connected in a phase winding, power devices are connected in the parallel windings wound in each pole of stator in the proposed method. Paralleling strategy for current sharing in the proposed method can be easily determined without considerations of any nonlinear characteristics of power devices such as conduction resistance, threshold voltage and gain factor. The proposed paralleling strategy is verified by the mathematical analysis and experimental results.