• ETRI Journal
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• v.25 no.6
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• pp.535-537
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• 2003

We propose a rigorous 2D approximation technique for the 3D waveguide structures; it can minimize the well-known approximation errors of the commonly used effective index method. The main concept of the proposed technique is to compensate for the effective cladding index in the equivalent slab model of the original channel waveguide from the modal effective index calculated by the nonuniform 2D finite difference method. With simulations, we used the proposed technique to calculate the coupling characteristics of a directional coupler by the 2D beam propagation method, and the results were almost exactly the same as the results calculated by the 3D beam propagation method.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.1
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• pp.1171-1177
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• 2001

This paper provides a guideline for specifying the operational compliance characteristics considering the location of compliance center and the grasp points in assembly tasks using robot hands. Through various assembly tasks, we analyze the conditions of the achievable operational stiffness matrix with respect to the location of compliance center and the grasp points. Also, we show that some of coupling stiffness elements in the operational space cannot be planned arbitrarily. As a result it is concluded that the location of compliance center on the grasped object and the grasp points play important roles for successful assembly tasks and also the operational stiffness matrix should be carefully specified by considering those conditions.

• Advances in materials Research
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• v.6 no.1
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• pp.45-63
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• 2017

In this article, static deflection and buckling of functionally graded (FG) nanoscale beams made of porous material are carried out based on the nonlocal Timoshenko beam model which captures the small scale influences. The exact position of neutral axis is fixed, to eliminate the stretching and bending coupling due to the unsymmetrical material change along the FG nanobeams thickness. The material properties of FG beam are graded through the thickness on the basis of the power-law form, which is modified to approximate the material properties with two models of porosity phases. By employing Hamilton's principle, the nonlocal governing equations of FG nanobeams are obtained and solved analytically for simply-supported boundary conditions via the Navier-type procedure. Numerical results for deflection and buckling of FG nanoscale beams are presented and validated with those existing in the literature. The influences of small scale parameter, power law index, porosity distribution and slenderness ratio on the static and stability responses of the FG nanobeams are all explored.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1252-1258
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• 2014

ROS is based on a graph architecture where processing takes place in nodes. Nodes communicate together by passing messages through topics based on the publish/subscribe model. On the other hand, OPRoS components know each other and are tightly-coupled via port connections, and different coupling schemes make the interoperation between two platforms difficult. This paper describes an extension of OPRoS framework to support the interoperation with the ROS topic.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.185-190
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• 2001

Rotating disks are used in various machines such as floppy disks, hard disk, turbines and circular sawblades. The problems of vibrations of rotating disks are important in improving these machines. Many investigators have dealt with these problem. Specially, vibrations of a rotating flexible disk taking into account the effect of air is difficult problem in simulation. The governing equation of a rotating flexible disk coupled to the surrounding fluid is investigated by a simple mathematical model. And several important parameters concerned with the stability of a rotating flexible disk are defined. Coupling strength between air and rotating flexible disk is proportional to square of disk radius directly and square root of the all of bending rigidity, disk density and thickness inversely. Lift-to-damping coefficient has relation to the onset of disk flutter.

• Computational Structural Engineering
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• v.6 no.4
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• pp.73-82
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• 1993

Investigated in this paper is the effect of fluid-structure interaction between reactor internal components due to their immersion in a confining fluid on the dynamic responses. A non-linear mathematical model is developed for the dynamic analysis of the reactor internals, which includes lumped masses, stiffnesses and hydrodynamic couplings. The hydrodynamic mass matrix which characterizes the fluid-structure interaction is calculated. Also, the equations of motion containing hydrodynamic mass matrix are presented. The responses of the reactor internals due to seismic and pipe break excitations are obtained for the case of with- and without-hydrodynamic couplings and the different response characteristics are investigated.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.396-400
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• 2009

In this paper, electromagnetic topology (EMT) was used to analyze the electromagnetic compatibility (EMC) of RF circuits including passive and active components. It is difficult to obtain usable results for problems relating to electromagnetic coupling in complex systems when using conventional numerical or experimental methods. Thus it is necessary to find a new methodology for analyzing EMC problems in complicated electromagnetic environments. In order to consider the nonlinear characteristics of active components, a SPICE diode model was used. A power detector circuit and the receiver circuit of a radio control (RC) car were analyzed and experimented in order to verify the validity of this method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1626-1631
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• 2007

This paper presents a new modeling method using lamp output power and the modeling coefficients of the lamp. The proposed method utilizes the lamp modeling coefficients such as equivalent impedance Z(p), coupling coefficient of the transformer k(p), turns ratio of the transformer n(p), and plasma resistance Rp(p) as a function of lamp output power. The equivalent impedance Z(p) was developed from the equivalent resistance Req(p) and equivalent inductance Leq(p) of the lamp. Simulation and experimental results of the proposed model are presented in order to validate the proposed method. The modeling method can use to design an impedance matching circuit for a Class-D inverter.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.539-545
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• 2001

This paper proposes a static synchronous series compensator based on multi-bridge inverter. The proposed system consists of 6 H-bridge modules per phase, which generate 13 pulses for each half period of power frequency. The dynamic characteristic was analyzed by simulations with EMTP code, assuming that it is inserted in the 154-kV transmission line of one-machine-infinite-bus power system. The feasibility of hardware implementation was verified through experimental works using a scaled model. The proposed system does not require a coupling transformer for voltage injection, and has flexibility in expanding the operation voltage by increasing the number of H-bridge modules.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.718-722
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• 2001

This paper proposes an SSSC based on multi-bridge inverters in PWM scheme. The proposed system consists of 6 H-bridge inverter modules per phase. The dynamic characteristic of proposed system was analyzed by simulation with EMTP codes, assuming that the SSSC is inserted in the 154-kV transmission line of one-machine-infinite-bus power system. The feasibility of hardware implementation was verified through experimental works with a scaled-model. The proposed system can be directly inserted in the transmission line without coupling transformers, and has flexibility in expanding the operation voltage by increasing the number of H-bridges.