• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.613-615
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• 1996

Harmonic elimination method of using coupling transformer in twelve pulse inverter is presented for high power application. This method is using coupling transformer and PWM(pulse width modulation) switching and voltage source inverter. The object of proposed harmonic elimination method is obtained inverter output of low THD(Total Harmonic Distortion). The simulation results confirm the proposed harmonic elimination method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1366-1371
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• 2006

A structural coupling method is developed for the dynamic analysis of a nonlinear structure with concentrated nonlinear hinge joints or sliding lines. Component mode synthesis method is extended to couple substructures and the nonlinear models. In order to verify the improved coupling method, a numerical plate model consisting of two substructures and torsional springs, is synthesized by using the proposed method and its model parameters are compared with analysis data. Then the coupling method is applied to a three-substructure-model with the nonlinearity of sliding lines between the substructures. The coupled structural model is verified from its dynamic analysis. The analysis results show that the improved coupling method is adequate for the structural nonlinear analyses with the nonlinear hinge and sliding mode condition.

• Fire Science and Engineering
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• v.33 no.1
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• pp.121-129
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• 2019

In Korea, life safety assessment through simulation are mandatory in performance-based design. Generally, there are three types of methods for simulation-based life safety assessments: the non-coupling method that compares available safe egress time (ASET) and required safe egress time (RSET) at a specific point through conducting fire and assessment simulations independently; the semi-coupling method that compares fire and evacuation simulation results by overlaying the result screens; and the coupling method that compares the results of fire effect simulation to an evacuation simulation. Of these methods, all designers in South Korea have used the only non-coupling method. In the non-coupling method, it is important to determine the location of a specific point to compare ASET and RSET. However, without any defined regulation, setting the location is determined based on the designer's experience and knowledge. The number of specific locations and the locations themselves differ with each designer, which can produce contrasting results in a life safety assessment. Therefore, this study conducted a life safety assessment based on the three methods (non-coupling, semi-coupling and coupling) and compared each of the results. Furthermore this study suggests a improvement way in particular for the computer simulation.

• Interaction and multiscale mechanics
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• v.1 no.1
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• pp.1-31
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• 2008

The present paper presents multiscale modelling via coupling of the discrete and finite element methods. Theoretical formulation of the discrete element method using spherical or cylindrical particles has been briefly reviewed. Basic equations of the finite element method using the explicit time integration have been given. The micr-macro transition for the discrete element method has been discussed. Theoretical formulations for macroscopic stress and strain tensors have been given. Determination of macroscopic constitutive properties using dimensionless micro-macro relationships has been proposed. The formulation of the multiscale DEM/FEM model employing the DEM and FEM in different subdomains of the same body has been presented. The coupling allows the use of partially overlapping DEM and FEM subdomains. The overlap zone in the two coupling algorithms is introduced in order to provide a smooth transition from one discretization method to the other. Coupling between the DEM and FEM subdomains is provided by additional kinematic constraints imposed by means of either the Lagrange multipliers or penalty function method. The coupled DEM/FEM formulation has been implemented in the authors' own numerical program. Good performance of the numerical algorithms has been demonstrated in a number of examples.

• YAKHAK HOEJI
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• v.37 no.6
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• pp.615-620
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• 1993

The cross-coupling reaction of organo tin reagents with a variety of organic halides, catalyzed by palladium, provides a novel method for generating a carbon-carbon bond. We used this method for the antibacterial agents, and synthesis of new quinolone derivatives which have carbon-carbon bond at C-7 position of general quinolone moieties. Aryl tin, quinolone moieties, and palladium catalyst were refluxed in DMF to afford new quinolone derivatives. This palladium catalyzed coupling reactions have capacity for further synthetic elaboration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.7
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• pp.951-958
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• 1993

The coupling length is very important factor for the study of directional coupler and other intergrated-optic devices. And the calculation of coupling length is the fundamental process of studing various types of intergrated optical devices. But the calculation of coupling length, requires coupling coefficient n. and the evaluation of coupling coefficient f is very tedious because it requires the calculation of overlap intergral of the two modes. Because of above reason, we suggest the use of beam propagation method, We suggest the basic configuration of directional coupler, which has three different types of longitudinal to vertical ratio, and calculate the coupling length of sugested configuration by both coupled mode thery and beam propagation method and compare the results of each method.

• Coupled systems mechanics
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• v.1 no.1
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• pp.19-37
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• 2012

In this work, the iterative coupling of finite element and boundary element methods for the investigation of coupled fluid-fluid, solid-solid and fluid-solid wave propagation models is reviewed. In order to perform the coupling of the two numerical methods, a successive renewal of the variables on the common interface between the two sub-domains is performed through an iterative procedure until convergence is achieved. In the case of local nonlinearities within the finite element sub-domain, it is straightforward to perform the iterative coupling together with the iterations needed to solve the nonlinear system. In particular, a more efficient and stable performance of the coupling procedure is achieved by a special formulation that allows to use different time steps in each sub-domain. Optimized relaxation parameters are also considered in the analyses, in order to speed up and/or to ensure the convergence of the iterative process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.101-105
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• 2002

In this paper, the coupling windows of the dielectric resonator filter have been analyzed. The coupling factor which has been used to characterize the coupling window is represented by closed form expressions. The deviation of the coupling factor as the size of coupling window has been compared between calculated by presented method and measured ones. There are very closed agreements. The presented method can be applied not only to design dielectric resonator but also to design varactor tuned dielectric resonator filter so as that the passband bandwidth is constant within tuned ranges.

• Journal of IKEEE
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• v.23 no.1
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• pp.306-309
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• 2019

Wireless charging is a technology of transmitting power through an air gap to an electrical load for the purpose of energy dissemination. Compared to traditional charging with code, wireless power charging has many benefits of avoiding the hassle from connecting cables, rendering the design and fabrication of much smaller devices without the attachment of batteries, providing flexibility for devices, and enhancing energy efficiency, etc. A transmitting coil and a receiving coil for inductive coupling or magnetic resonant coupling methods are available for the near field techniques, but are not for the far field one. In this paper, the wireless power transfer (WPT) circuit by using magnetic resonant coupling method with a resonant frequency of 13.45 Mhz for the low power system is implemented to measure the power transmission efficiency in terms of mutual distance and omnidirectional angles of receiver.

• ETRI Journal
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• v.28 no.2
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• pp.223-226
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• 2006

This letter presents a new approach to synthesize the resonator filters of an arbitrary topology. This method employs an optimization method based on the relation between the polynomial coefficients of the transfer function and those of the $S_{21}$ from the coupling matrix. Therefore, this new method can also be applied to self-equalized filters that were not considered in the conventional optimization methods. Two microwave filters, a symmetric 4-pole filter with four transmission zeros (TZs) and an asymmetric 8-pole filter with seven TZs, are synthesized using the present method for validation. Excellent agreement between the response of the transfer function and that of the synthesized $S_{21}$ from the coupling matrix is shown.