• Coupled systems mechanics
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• v.4 no.2
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• pp.137-155
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• 2015

This paper presents a simple procedure to obtain a substitute, homogenized mechanical response of single layer graphene sheet. The procedure is based on the judicious combination of molecular mechanics simulation results and homogenization method. Moreover, a series of virtual experiments are performed on the representative graphene lattice. Following these results, the constitutive model development is based on the well-established continuum mechanics framework, that is, the non-linear membrane theory which includes the hyperelastic model in terms of principal stretches. A proof-of-concept and performance is shown on a simple model problem where the hyperelastic strain energy density function is chosen in polynomial form.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.129-139
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• 1985

Small-scale hydropower systems offer several advantages compared to other alternatives as an important source of energy in both developed and developing countries. This study proposes systematic criteria for screening of small-scale hydropower sites to determine their potential for farther study, and demonstrates the general procedure. These criteria are based on the physical characteristics of the sites and their social, environmental and economic aspects. The procedure presented shows great flexibility for screening based on the availability of information and situation at the site.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1424-1430
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• 2013

This paper presents design procedure of the magnetic bearings used for high-speed electric machines and flywheel energy storage systems. Magnetic bearing can be categorized by inner-rotor type and outer-rotor type according to the position of the rotary disc. These two types are applicable based on application environments such as application space, required attraction force, and controllability. Magnetic bearing is generally designed based on the ratio (geometrical coefficient or geometrical efficiency) of pole width to rotor journal radius but proper ratio is only decided by the analysis. This is the difficulty of the magnetic bearing design. In this paper, proper design technology of the inner-rotor type and outer-rotor-type eight pole magnetic bearings is introduced and compared with the FEM analysis results, which verifies the proposed design procedure is suitable to be applied to the design of the magnetic bearings for the industrial applications and flywheel energy storage system.

• Geophysics and Geophysical Exploration
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• v.17 no.2
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• pp.95-103
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• 2014

This paper presents a practical inversion method for recovering a three-dimensional (3D) resistivity model and static shifts simultaneously. Although this method is based on a Gauss-Newton approach that requires a sensitivity matrix, the computer time can be greatly reduced by implementing a simple and effective procedure for updating the sensitivity matrix using the Broyden's algorithm. In this research, we examine the approximate inversion procedure and the weighting factor ${\beta}$ for static shifts through inversion experiments using synthetic MT data. In methods using the full sensitivity matrix constructed only once in the iteration process, a procedure using the full sensitivity in the earlier stage is useful to produce the smallest rms data misfit. The choice of ${\beta}$ is not critical below some threshold value. Synthetic examples demonstrate that the method proposed in this paper is effective in reconstructing a 3D resistivity structure from static-shifted MT data.

• New & Renewable Energy
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• v.18 no.1
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• pp.17-28
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• 2022

This paper presents an effective Markov transition matrix (EMTM), which will be used to calculate the wind speed at the target site in a wind farm to accurately predict wind energy production. The existing MTS prediction method using a Markov transition matrix (MTM) exhibits a limitation where significant prediction variations are observed owing to random selection errors and its bin width. The proposed method selects the effective states of the MTM and refines its bin width to reduce the error of random selection during a gap filling procedure in MTS. The EMTM reduces the level of variation in the repeated prediction of wind speed by using the coefficient of variations and range of variations. In a case study, MTS exhibited better performance than other MCP models when EMTM was applied to estimate a one-day wind speed, by using mean relative and root mean square errors.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.975-983
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• 2013

This study proposes a low order dynamic model of a building system in order to predict thermal behavior within a building and its energy consumption. The building system includes a thermally well-insulated room and an electric heater. It is modeled by a second order lumped RC thermal network based on the thermal-electrical analogy. In order to identify unknown parameters of the model, an experimental procedure is firstly detailed. Then, the different linear parametric models (ARMA, ARX, ARMAX, BJ, and OE models) are recalled. The parameters of the parametric models are obtained by the least square approach. The obtained parameters are interpreted to the parameters of the physically based model in accordance with their relationship. Afterwards, the obtained models are implemented in Matlab/Simulink(R) and are evaluated by the mean of the sum of absolute error (MAE) and the mean of the sum of square error (MSE) with the variable of indoor temperature of the room. Quantities of electrical energy and converted thermal energy are also compared. This study will permit a further study on Model Predictive Control adapting to the proposed model in order to reduce energy consumption of the building.

• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1157-1176
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• 2014

The objective of this research is to develop a practical design and assessment approach of steel frames with steel slit walls (SSWs) that focuses on the damage-control behavior to enhance the structural resilience. The yielding sequence of SSWs and frame components is found to be a critical issue for the damage-control behavior and the design of systems. The design concept is validated by the full-scale experiments presented in this paper. Based on a modified energy-balance model, a procedure for designing and assessing the system motivated by the framework regarding the equilibrium of the energy demand and the energy capacity is proposed. The damage-control spectra constructed by strength reduction factors calculated from single-degree-of-freedom systems considering the post stiffness are addressed. A quantitative damage-control index to evaluate the system is also derived. The applicability of the proposed approach is validated by the evaluation of example structures with nonlinear dynamic analyses. The observations regarding the structural response and the prediction during selected ground motions demonstrate that the proposed approach can be applied to damage-control design and assessment of systems with satisfactory accuracy.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.214-220
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• 2008

The Ballast Water Management Convention provides that ballast water treatment systems which make use of active substances shall be approved from IMO according to the procedure developed by the IMO. The Convention described that active substance means a substance or organism, including a virus or a fungus, that has a general or specific action on or against harmful aquatic organisms and pathogens. The Marine Environment Protection Committee of IMO gave basic approval to 13 ballast water management systems and final approval to 4 systems until October 2008. This paper considered the matter of procedure and documents of the basic and final approval based on the "Procedure for approval of ballast water management systems that make use of Active Substances (G9)" and "The Methodology for information gathering and the conduct of work of the GESAMP-BWWG" and summarized the specifications of the treatment systems which was granted the basic or final approval from IMO and raised several points.

• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.390-396
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• 1996

Piping Systems are usually designed for thermal expansion loads based on uniform temperatures at each cross section. However, in lines with low flow rates such as surge lines and spray lines, large transverse temperature gradients have been observed, resulting in too types of additional thermal stresses : (1) local thermal gradient stresses which are independent of routing and supports and (2) gross bending stresses due to induced pipe curvature which are routing and support system dependent. This paper presents a simplified method for analyzing a PER surge line for stratified flow.

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.35-44
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• 2003

The neutron induced nuclear data for Eu-153, Gd-155 and Cd-157 are calculated and evaluated in the high energy region. The evaluation procedure for deformed nuclei is setup by using Ecis-Empire codes. The energy dependent optical model potential parameters are searched based on the recent experimental data and applied up to 20 MeV. Optical model, full featured Hauser-Feshbach model and multistep direct and multistep compound model are used in the calculation. The direct-semidirect capture model and the direct coupled-channels contribution to discrete levels are introduced to improve the capture and inelastic scattering cross sections. The theoretically calculated cross sections are compared with the experimental data and the evaluated files. The model-calculated total and capture cross sections are in good agreement with the reference experimental data. The evaluated cross section results are compiled to ENDF-6 format and are expected to improve the ENDF/B-Vl.