• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.848-853
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• 2001

Electrostatic actuation was adopted for ease of fabrication. We proposed a new driving scheme that uses the vector sum of force generated by comb-finger and by parallel plate. The moving and fixed electrodes are arranged to maximize the driving force. In this paper, an electrostatic field analysis is performed by Maxwell analysis tool for micro actuators. From the analysis, a comb-parallel type micro-actuator with 4${\mu}{\textrm}{m}$ width, 6${\mu}{\textrm}{m}$ overlap and 45${\mu}{\textrm}{m}$ height could be designed. In order to compare the new type of actuator with the conventional comb type of actuator, we arranged that both types have the same area and the same number of actuators. To make a high aspect ratio structure, we are developing fabrication process using SU-8 and electro-plating.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.1035-1043
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• 2006

In this study, a translational 3-DOF parallel mechanism formed by constraining the Stewart Platform Mechanism is investigated. The translational 3-DOF parallel mechanism has three struts(3-UPS type serial subchains) and in addition, has a PPP type serial subchain in the middle of the mechanism. Firstly, the closed-form forward and reverse position solutions are derived for this mechanism. And analysis on kinematic characteristics using isotropic index of the Jacobian is conducted to examine effects of design parameters for the mechanism. Lastly, a prototype mechanism is implemented and the kinematic performance of the translational 3-DOF parallel mechanism was verified through experimental work.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.10
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• pp.817-825
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• 2016

In this paper, we introduce a flexible gripper that we have engineered to precisely pinch in parallel and compliantly grasp objects. As found in most conventional industrial grippers, the parallel pinching property is essential for precise manipulation. On the other hand, the grippers with a flexible structure are more adept at grasping objects with arbitrary shapes and softness. To achieve these disparate properties, we introduce a flexible gripper mechanism composed of multiple flexible beam structures. Utilizing these beam structures, the proposed gripper is able to grasp arbitrarily shaped objects. Additionally, a unique combination of flexible beams enables the gripper to pinch objects using the parallel fingertips for enhanced precision. A detailed description of the proposed mechanism is provided, and an analysis of the strength and stiffness of the fingertip and finger body is presented. The Results section compares the theoretical and experimental analyses and verifies the properties and performance of the proposed gripper.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1086-1095
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• 2013

The main issue of parallel three-phase boost converters is reduction of the low- and high frequency circulating currents. Most present technologies concentrate on low frequency circulating current because the circulating current controller cannot mitigate the high frequency circulating current. In this paper, analytical approach of three-phase coupled inductor applied to parallel system becomes an important objective to effectively reduce the low- and high frequency circulating currents. The characteristics of three-phase coupled inductor based on a structure and voltage equations are mathematically derived. The modified voltage equations are then applied to parallel three-phase boost converters to develop averaged models in stationary coordinates and rotating coordinates. Based on the averaged modeling approach, design of the circulating current controller is presented. Simulation and experimental results demonstrate the effectiveness of the analysis and modeling for the parallel three-phase boost converters using three-phase coupled inductor.

• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.814-819
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• 2004

The conceptual design of a rotorcraft system involves many different analysis disciplines. The decomposition of such a system into several subsystems can make analysis and design more efficient in terms of the total computation time. Adaptive parallel decomposition makes the structure of the overall design problem suitable to apply the multidisciplinary design optimization methodologies and it can exploit parallel computing. This study proposes a decomposition method which adaptively determines the number and sequence of analyses in each sub-problem corresponding to the available number of processors in parallel. A rotorcraft design problem is solved and as a result, the adaptive parallel decomposition method shows better performance than other previous methods for the selected design problem.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.735-741
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• 1992

This paper presents a parallel algorithm for the finite element analysis using relatively inexpensive transputer parallel system. The substructure method, which is highly parallel in nature, is used to improve the parallel computing efficiency by splitting up the whole structure into substructures. The proposed algorithm is applied to a simple two-dimensional magnetostatic problem. It is found that the more the number of transputer is increased, the more the total computation time is reduced. And the computational efficiency becomes better as the number of internal boundary nodes becomes smaller.

• Journal of the Korean Mathematical Society
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• v.54 no.3
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• pp.793-805
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• 2017

In this paper, we prove that the Ricci tensor of a three-dimensional almost Kenmotsu manifold satisfying ${\nabla}_{\xi}h=0$, $h{\neq}0$, is ${\eta}$-parallel if and only if the manifold is locally isometric to either the Riemannian product $\mathbb{H}^2(-4){\times}\mathbb{R}$ or a non-unimodular Lie group equipped with a left invariant non-Kenmotsu almost Kenmotsu structure.

• Nuclear Engineering and Technology
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• v.46 no.5
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• pp.655-666
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• 2014

The CUPID code has been developed at KAERI for a transient, three-dimensional analysis of a two-phase flow in light water nuclear reactor components. It can provide both a component-scale and a CFD-scale simulation by using a porous media or an open media model for a two-phase flow. In this paper, recent advances in the CUPID code are presented in three sections. First, the domain decomposition parallel method implemented in the CUPID code is described with the parallel efficiency test for multiple processors. Then, the coupling of CUPID-MARS via heat structure is introduced, where CUPID has been coupled with a system-scale thermal-hydraulics code, MARS, through the heat structure. The coupled code has been applied to a multi-scale thermal-hydraulic analysis of a pool mixing test. Finally, CUPID-SG is developed for analyzing two-phase flows in PWR steam generators. Physical models and validation results of CUPID-SG are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.130-139
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• 2004

The Casing Oscillator is a bore file Equipment for the all-casing process. All-casing process is a method of foundation work in construction yard to oscillate steel Casing in the ground. The existing Casing Oscillator has some problem like not boring horizontally with disturbance and not driving Casing othor angle except horizon. To solve problem, the new structure Casing Oscillator is presented and studied. The performance of Casing Oscillator is improved by kinematics analysis. The Casing Oscillator is similar to the parallel manipulator in structure. So we obtain Inverse kinematics solution of Casing Oscillator easily. But it is difficult to solve forward kinematics of Casing Oscillator. T his paper presents a novel pose description corresponding to the structure characteristics of parallel manipulators. Through analysis on geometry theory, we obtain a new method of the closed-form solution to the forward kinematics using Kinematic Inversion. The closed-form solution contains two different meanings -analytical and real-time. So we reach the goal of practical application and control. Closed-form forward kinematics solution is verified by an inverse kinematics analysis. It shows that the method has a practical value for real -time control and inverse kinematics servo control.

• Structural Engineering and Mechanics
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• v.9 no.4
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• pp.383-396
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• 2000

A new structure-vibration-control approach is proposed which uses a passive coupling element between two parallel structures to reduce the seismic response of a system due to earthquake excitation. Dynamic characteristics of the two coupled single-degree-freedom systems subject to stationary white-noise excitation are examined by means of statistical energy analysis (SEA) techniques. Optimal parameters of the passive coupling element such as damping and stiffness under different circumstances are determined with an emphasis on the influence of the structural parameters of the system on the optimal parameters and control effectiveness. Numerical results including the root mean square values of the response due to the filtered white-noise excitation and the time-histories of response to El Centro 1940 NS excitation are presented.