• Environmental and Resource Economics Review
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• v.23 no.3
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• pp.365-408
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• 2014

The purpose of this paper is to compare efficiencies, two stage efficiencies, and the reduction of economic growth due to the restraint of $CO_2$ and fossil fuel in two efficiency approach by pointing out the limit of traditional efficiency approach and introducing material balance approach. The efficiencies under the traditional approach and the material balance approach report significant gaps when they are analyzed in detail. Especially, in case not including fossil fuels, the low income countries show the bad performance of production efficiencies, but OECD and high-middle income countries reveal the better performance than that of the low countries. It fails to reflect the reality justly. Based on the material balance approach, the low income countries report the higher performance and the alleviated effect of environmental components for economic growth than OECD's.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.58-68
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• 1994

An equilibrium approach is suggested as an effective tool for the analysis of sheet metal forming processes on the basis of force balance together with geometric relations and plasticity theroy. In computing a force balance equation, it is required to define a geometric curve approximating the shape of the sheet metal at any step of deformation from the geometric interaction between the die and the deforming sheet. Then the geometic informations for contacting and non-contacting sections of the sheet metal such as the number and length of both non-contact region, contact angle, and die radius of contact section are known from the geometric forming curve and utilized for optimization by force balance equation. In computation, the sheet material is assumed to be of normal amisotropy and rigid-phastic workhardening. It has been shown that there are good agreements between the equilibrium approach and FEM computation for the benchmark test example and auto-body panels whose sections can be assumed in plane-strain state. The proposed equilibrium approach can thus be used as a robust computational method in estimating the forming defects and forming severity rather quickly in the die design stage.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.66-71
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• 2001

A sectional analysis of trunk-lid carried out by using the equilibrium approach based on the force balance together with geometric relations and plasticity theory. In computing a force balance equation, it is required to define a geometric curve approximating the shape of sheet metal at any step of deformation from the interaction between the die and the deformed sheet. The trunk-lid panel material is assumed to possess normal anisotropy and to obey Hill's new yield criterion. Deformation of each section of trunk-lid panel is simulated and composed to get the three-dimensional shape by using CAD technique. It was shown that the three-dimensional shape composition of the two-dimensional analysis.

• 한국가스학회:학술대회논문집
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• 1998.09a
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• pp.241-246
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• 1998

This paper considers the applicability of a pseudosteady-state approach to the long-time behavior of real gas flow in a closed reservoir. The method involves a combination of a linearized gas diffusivity equation using a normalized pseudotime and a material balance equation. Comparison with a commercial reservoir simulator showed that highly accurate values of pseudopressure drawdown and well pressure are obtained by the pseudosteady-state approach with much less computational effort.

• Journal of Environmental Policy
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• v.3 no.1
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• pp.95-117
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• 2004

This study was conducted to estimate nitrogen discharge from Korea (southern part of Korean peninsula) as NPS(non-point source) by mass balance approach; input and output analyses of nitrogen using existing data available. The material flow was sectored into three different activities; agricultural (raising crop and animals), human and natural activities in forest and urban areas. Atmospheric deposition, biological nitrogen fixation, inorganic fertilizers and manures applied, animal feed and imported foodstuffs such as crops, meat and fish were the inputs in this study, while ammonia volatilization, denitrification, human and animal waste generation, crop and meat production, and discharge into river to ocean were the outputs. The estimated total nitrogen input was $1,194.5{\times}10^3$ tons N/year and the river discharge was 408 to $422{\times}10^3$ tons N/year, of which 66 to 71% was from NPS. In detail, the estimated NPS discharges were respectively $8,274\;kg\;N/km^2$/year from agricultural area, $730\;kg\;N/km^2$/year from forest and $7,657\;kg\;N/km^2$/year from the other land areas such as urban and industrial area.

• Steel and Composite Structures
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• v.28 no.1
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• pp.111-121
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• 2018

It has been argued that fracture energy of composite laminates depends on their thickness and number of layers. In this paper a modified direct energy balance approach (DEBA) has been developed to evaluate the mode-II shear fracture energy for E-glass/Epoxy laminates from finite element model at an arbitrary thickness. This approach considers friction and damage/plasticity deformations using cohesive zone modeling (CZM) and nonlinear finite element modeling. The presence of compressive stress and resulting friction was argued to be a possible cause for the thickness dependency of fracture energy. In the finite element modeling, CZM formulation has been developed with bilinear cohesive constitutive law combined with friction consideration. Also ply element have been developed with shear plastic damage model. Modified direct energy balance approach has been proposed for estimation of mode-II shear fracture energy. Experiments were performed on laminates of glass epoxy specimens for characterization of material parameters and determination of mode-II fracture energies for different thicknesses. Effect of laminate thickness on fracture energy of transverse crack tension (TCT) and end notched flexure (ENF) specimens has been numerically studied and comparison with experimental results has been made. It is shown that the developed numerical approach is capable of estimating increase in fracture energy due to size effect.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1753-1762
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• 2000

An inverse method is presented to obtain material's flow properties by using small punch test. This procedure employs, as the objective function of inverse analysis, the balance of measured load-di splacement response and calculated one during deformation. In order to guarantee convergence to global minimum, simulated annealing method was adopted to optimize the current objective function. In addition, artificial neural network was used to predict the load-displacement response under given material parameters which is the most time consuming and limits applications of global optimization methods to these kinds of problems. By implementing the simulated annealing for optimization along with calculating load-displacement curve by neural network, material parameters were identified irrespective of initial values within very short time for simulated test data. We also tested the present method for error-containing experimental data and showed that the flow properties of material were well predicted.

• Steel and Composite Structures
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• v.46 no.5
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• pp.659-667
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• 2023

Nonlinear forced vibration behaviors of sandwich plates having graphene platelets (GPL) based face sheets have been researched in this article. Possessing low weight together with low stiffness, square honeycomb cores are mostly constructed by aluminum. Herein, the square shaped core has been fortified by two skins of GPL-based type in such a way that the skins have uniform and linearly graded GPL dispersions. The square shaped core has the effective material specification according to the relative density concept. The whole formulation has been represented based upon classical plate theory (CPT) while harmonic balance approach is applied for solving the problem and plotting the amplitude-frequency curves. The forced vibration behaviors of such plates are influenced by square-shaped core and the relative density, skin's height and GPL fortification.

• Coupled systems mechanics
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• v.11 no.6
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• pp.543-556
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• 2022

Delamination of multilayered inhomogeneous beam that exhibits non-linear relaxation behavior is analyzed in the present paper. The layers are inhomogeneous in the thickness direction. The dealamination crack is located symmetrically with respect to the mid-span. The relaxation is treated by applying a non-linear stress-straintime constitutive relation. The material properties which are involved in the constitutive relation are distributed continuously along the thickness direction of the layer. The delamination is analyzed by applying the J-integral approach. A time-dependent solution to the J-integral that accounts for the non-linear relaxation behavior is derived. The delamination is studied also in terms of the time-dependent strain energy release rate. The balance of the energy is analyzed in order to obtain a non-linear time-dependent solution to the strain energy release rate. The fact that the strain energy release rate is identical with the J-integral value proves the correctness of the non-linear solutions derived in the present paper. The variation of the J-integral value with time due to the non-linear relaxation behavior is evaluated by applying the solution derived.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.73-78
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• 1998

This paper considers the applicability of a pseudosteady-state approach to the long-time behavior of real gas flow in a closed reservoir. The method involves a combination of a linearized gas diffusivity equation using a normalized pseudotime and a material balance equation. For the simulation of field-scale problems with multiple wells of differing production rates over extended production periods, the pseudosteady-state equation was solved successively for each flow period. Results from this study show that the approach provides a fast and accurate method for modeling the long-time behavior of gas reservoirs under depletion conditions.