• Advances in nano research
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• v.9 no.2
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• pp.91-104
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• 2020

The bending, stability (buckling) and vibration response of nano sized beams is presented in this study based on the Eringen's nonlocal elasticity theory in conjunction with the Euler-Bernoulli beam theory. For this purpose, the bending, buckling and vibration problem of Euler-Bernoulli nanobeams are developed and solved on the basis of nonlocal elasticity theory. The effects of various parameters such as nonlocal parameter e₀a, length of beam L, mode number n, distributed load q and cross-section on the bending, buckling and vibration behaviors of carbon nanotubes idealized as Euler-Bernoulli nanobeam is investigated. The transverse deflections, maximum transverse deflections, vibrational frequency and buckling load values of carbon nanotubes are given in tables and graphs.

• Structural Engineering and Mechanics
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• v.64 no.6
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• pp.751-763
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• 2017

This article deals with the buckling behaviour of multilayered magneto-electro-elastic (MEE) plate subjected to uniaxial and biaxial compressive (in-plane) loads. The constitutive equations of MEE material are used to derive a finite element (FE) formulation involving the coupling between electric, magnetic and elastic fields. The displacement field corresponding to first order shear deformation theory (FSDT) has been employed. The in-plane stress distribution within the MEE plate existing due to the enacted force is considered to be equivalent to the applied in-plane compressive load in the pre-buckling range. The same stress distribution is used to derive the potential energy functional. The non-dimensional critical buckling load is accomplished from the solution of allied linear eigenvalue problem. Influence of stacking sequence, span to thickness ratio, aspect ratio, load factor and boundary condition on critical buckling load and their corresponding mode shape is investigated. In addition, static deflection of MEE plate under the sinusoidal and the uniformly distributed load has been studied for different stacking sequences and boundary conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.55-62
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• 2011

PCS(Power Conditioning System) is the necessary component in Microgrid, composed of multiple distributed generators and energy storage system. In this paper, the functions of PCS are defined and 10[kW] PCS for PV and BESS are developed. To apply PCSs to Microgrid, this paper presents a 3-phase inverter with the decoupling current controller, voltage controller and DPLL control system. PCSs were applied to 120[kW] pilot plant and its performance tests were carried out. Test results of PCS at each operation mode show stable in Microgrid.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.141-143
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• 2004

Distributed generation(DG) using microturbine will be adopted widely because of its various usages and merits such as high heat efficiency, environmental-friendliness. Commercialized DG using microtubine that rotates up to $60,000\~100,000[rpm]$ converters mechanical power to electricity by permanent magnet synchronous machine. This paper presents comparative test and simulation results of PMSM as generator. Test was done by diode rectifier and inverter. Parameters used in the simulation are driven from FEM analysis. Under various speed and load conditions, V-I characteristics matches well and it suggests the possibility of high speed PMSM as generator. DG operating at stand alone and grid connection mode will be developed.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.277-279
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• 2005

Generally, It was used to use a unit of a Large regularity in developing Large Capacity Converter System of the electric power. Lager a capacity of a unit of regularity, more expensive cost of it. So, normally, We overcome the limit of a proper form of an electricity semiconductor which be used in application field of Large capacity electricity conversion system through the Composition of Multi-level Circuit or Dual-Mode or parallel switch. but some problem is discussed. Using parallel RC-diode circuit instead of Large Capacity diode, We implemented a circuit that it overcome the limit of a regularity with dealing current distributed by parallel RC-diode circuit.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.3
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• pp.266-281
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• 2017

Hydroelastic interactions of a deformable floating body with random waves are investigated in time domain. Both hydroelastic motion and structural dynamics are solved by expansion of elastic modes and Fourier transform for the random waves. A direct and efficient structural analysis in time domain is developed. In particular, an efficient way of obtaining distributive loads for the hydrodynamic integral terms including convolution integral by using Fubini theory is explained. After confirming correctness of respective loading components, calculations of full distributions of loads in random waves are expedited by reformulating all the body loading terms into distributed forms. The method is validated by extensive convergence tests and comparisons against the counterparts of the frequency-domain analysis. Characteristics of motion/deformation responses and stress resultants are investigated through a parametric study with varying bending rigidity and types of random waves. Relative contributions of componential loads are identified. The consequence of elastic-mode resonance is underscored.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.155-163
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• 2000

A general characterization procedure based on the extraction of a 2n-port admittance matrix corresponding to n uniform coupled lines on the multi-layered substrate using the Finite-Difference Time-Domain (FDTD) technique is presented. The frequency-dependent normal mode parameters are obtained from the 2n-port admittance matrix, which in turn provides the frequency-dependent distributed inductance and capacitance matrices. To illustrate the technique, several practical coupled line structures on multi-layered substrate, including a three-line structure, have been simulated. It is shown that the FDTD based time domain characterization procedure is an excellent broadband simulation tool for the design of multiconductor coupled lines on multilayered PCBs as well as thick or thin hybrid structures.

• Journal of information and communication convergence engineering
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• v.12 no.2
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• pp.75-82
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• 2014

Dispersion management (DM), optical phase conjugation (OPC), and the combination of DM and OPC are promising techniques to compensate for optical signal distortion due to group velocity dispersion and nonlinear Kerr effects. The system performance improvement in DM links combined with OPC has been reported; however, the fixed residual dispersion per span (RDPS) usually used in these links restricts the flexibility of link configuration. Thus, in this paper, a flexible optical link configuration with artificially distributed single-mode fiber (SMF) lengths and RDPS in the combination of DM and OPC is proposed. Simulation results show that the best artificial distribution pattern is the gradually descending distribution of SMF lengths and the gradually ascending distribution of RDPS, as the number of fiber spans is increased, regardless of the average RDPS, the optimal net residual dispersion, and the dispersion coefficient of the dispersion compensating fiber.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.871-873
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• 1999

According to the reports about the failure mode analysis of modules and systems, It is said that there are many early failure of system. To remove latent defects which causes early failures like that, It is necessary that screening test is performed. ESS is often used fur screening electronic equipments, and is proposed by the most powerful tool for removing latent defects of electronic equipments. [1][2] In this report, the procedure of the environmental stress screening which uses the temperature cycling stress is proposed. It is considered about environmental conditions of distributed control system(DCS) to be tested, design specifications of the system, recommended conditions of relative IEC-STD and applied conditions of similar company. ESS test was applied at the DCS to be installed in power plant. As the results of analyzing discovered problems. It was found that almost latent defects of electronic control systems was discovered early.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.10
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• pp.767-776
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• 2003

The theoretical method is developed to Investigate the nitration characteristics of the combined cylindrical shells with an annular plate joined to the shell at any arbitrary axial position. The structural coupling between shell and plate is simulated using two types of artificial springs a translational spring is introduced for translational coupling and a rotational spring is used for rotational coupling. The springs are continuously distributed along circumferential direction. Using the Rayleigh-Ritz method the natural frequencies and mode shapes of the combined shell with an annular plate examine. The effect of Inner-to-outer radius ratio, axial position of annular plate and length-to-radius ratio of shell on vibration characteristics of combined cylindrical shells is studied. The theoretical results are verified by comparison with FEM results.