• Journal of Environmental Policy
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• v.11 no.2
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• pp.55-71
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• 2012

This paper attempts to estimate the energy price elasticity of per capita $CO_2$ emissions, which helps to understand the influence of recent energy price increase on the natural reduction of $CO_2$ emissions. For this purpose, this study researched panel data of twenty-nine OECD countries from 1978 to 2009 and adopted estimation models for testing the environmental Kuznets hypothesis. Estimation results show that the 1% increase of energy price index will cause a statistically significant decrease of per capita $CO_2$ emissions by 0.26 ~ 0.31%, which is substantial enough for policy consideration. Also Kuznet curves in estimation models were identifed, the turning points of income lie between 22.2~48.5 thousand US dollars, depending on model specifications.

• Advances in nano research
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• v.15 no.6
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• pp.495-511
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• 2023

In this research, the impact of micro-silica, nano-silica, and polypropylene fibers on the fracture energy of self-compacting concrete was thoroughly examined. Enhancing the fracture energy is very important to increase the crack propagation resistance. The study focused on evaluating the self-compacting properties of the concrete through various tests, including J-ring, V-funnel, slump flow, and T50 tests. Additionally, the mechanical properties of the concrete, such as compressive and tensile strengths, modulus of elasticity, and fracture parameters were investigated on hardened specimens after 28 days. The results demonstrated that the incorporation of micro-silica and nano-silica not only decreased the rheological aspects of self-compacting concrete but also significantly enhanced its mechanical properties, particularly the compressive strength. On the other hand, the inclusion of polypropylene fibers had a positive impact on fracture parameters, tensile strength, and flexural strength of the specimens. Utilizing the response surface method, the relationship between micro-silica, nano-silica, and fibers was established. The optimal combination for achieving the highest compressive strength was found to be 5% micro-silica, 0.75% nano-silica, and 0.1% fibers. Furthermore, for obtaining the best mixture with superior tensile strength, flexural strength, modulus of elasticity, and fracture energy, the ideal proportion was determined as 5% micro-silica, 0.75% nano-silica, and 0.15% fibers. Compared to the control mixture, the aforementioned parameters showed significant improvements of 26.3%, 30.3%, 34.3%, and 34.3%, respectively. In order to accurately model the tensile cracking of concrete, the authors used softening curves derived from an inverse algorithm proposed by them. This method allowed for a precise and detailed analysis of the concrete under tensile stress. This study explores the effects of micro-silica, nano-silica, and polypropylene fibers on self-compacting concrete and shows their influences on the fracture energy and various mechanical properties of the concrete. The results offer valuable insights for optimizing the concrete mix to achieve desired strength and performance characteristics.

• Journal of Korea Foresty Energy
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• v.22 no.2
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• pp.60-68
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• 2003

In forest products industry, a variety of nondestructive evaluation techniques are now being used to assess the mechanical properties of structural lumber. Ultrasonic and longitudinal vibration technique are frequently used to assess the modulus of elasticity(MOE) of lumber. The objective of this research was to evaluate the MOE and modulus of rupture(MOR) of small-diameter of Larix log(Larix kaempferi Carr.), using these techniques. In this study, 50 small-diameter logs were nondestructiveively evaluated. The dynamic modulus of elasticity(Eu) of the logs was first evaluated, using an ultrasonic method. After ultrasonic tests, the logs were measured using a longitudinal vibration technique(Ev). Static bending test was then performed on the logs to obtain the static modulus of elasticity(Es) and modulus of rupture of these logs. In general, the dynamic MOE (Ev) of logs was closely co..elated with the stati, MOE for log. Based on the results of these experiments, it can be concluded that small-diameter Larix logs can be successfully evaluated by Ultrasonic and longitudinal vibration technique. The experimental results indicated that the ultrasonic technique is effective to the log, which contains many knots. The longitudinal vibration technique is effective to the log, in which many cracks are included.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.39-44
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• 1992

This paper proposes a method of h-type adaptive mesh generation for the finite element analysis of two dimensional elasticity problem. The error energy norm of a posteriori error estimation is difined based on the complementary energy of each element. Computer codes are developed and some examples are investigated. It is shown that the approach to the optimized mesh in this paper is effective and useful.

• Journal of applied mathematics & informatics
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• v.8 no.3
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• pp.919-934
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• 2001

The concepts of material frame-indifference and material symmetry group with respect to isotropic scalar functions, as represented by energy functions, are discussed. An energy function for a structured heterogeneous (transversal isotropic) medium in large elastic deformations, which is known to satisfy the Ponyting’s effect [1], is highlighted. It is shown that the constitutive relation due to this energt function is material frame-indifferent.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.27-29
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• 2004

The responses of hypothetical silicon nanotubes under torsion have been investigated using an atomistic simulation based on the Tersoff potential. A torque, proportional to the deformation within Hooke's law, resulted in the ribbon-like flattened shapes and eventually led to a breaking of hypothetical silicon nanotubes. Each shape change of hypothetical silicon nanotubes corresponded to an abrupt energy change and a singularity in the strain energy curve as a function of the external tangential force, torque, or twisted angle. The dynamics of silicon nanotubes under torsion can be modelled in the continuum elasticity theory.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.63-66
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• 2004

The responses of hypothetical silicon nanotubes under torsion have been investigated using an atomistic simulation based on the Tersoff potential. A torque, proportional to the deformation within Hooke's law, resulted in the ribbon-like flattened shapes and eventually led to a breaking of hypothetical silicon nanotubes. Each shape change of hypothetical silicon nanotubes corresponded to an abrupt energy change and a singularity in the strain energy curve as a function of the external tangential force, torque, or twisted angle. The dynamics of silicon nanotubes under torsion can be modelled in the continuum elasticity theory.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.145-151
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• 1997

The R&D investment of power industry has significant influences on the social welfare as well as national economy. It is necessary to analyze how efficient the R&D investment has been performed. The objective of this study is to verify the efficiency of the R&D investment in the domestic power industry. A formula was introduced to by calculate the appropriate amount of R&D investment of monopolistic industry under the regulations which are determined by the proportion of R&D elasticity and price elasticity. It has resulted that there would be no economy of scale as the sales of electricity increases at the same rate of the increasing cost. The R&D investment in the present electricity industry has been performed inefficiently by showing the negative impact on price-cost margin of the intensity of R&D investment, which is the extent of R&D investment to reinforce economy of scale.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.455-461
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• 2009

This paper proposes Direct Load Control(DLC) operation scheme using a bidding system and the methodology to value proper quantity decided by the DLC program, which is a kind of resources for stabilization of electricity market price during peak times by managing consumer electricity demand. Since DLC program in Korea is based on the contract with the customers participating in this program, it is difficult to anticipate voluntary participation. That is, incentive for participants in DLC program is insufficient. To cope with this point, it is necessary to develop a new market mechanism and market compatible operation scheme for DLC programs. DLC market mechanism is deemed to be equipped with iterative bidding system, independent operation from energy market, and interactive with bidding information on energy market. With this market mechanism, it is important to find the optimal operation point of DLC allowing for the factors of stabilizing the electricity market price and compensating DLC implementation. This paper focuses on the mathematical approaches for the bid-based DLC operation scheme and examines several scenarios for the following technical justifications: 1) stabilization of electricity market price during peak times, 2) elasticity of demand.

• Coupled systems mechanics
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• v.5 no.3
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• pp.255-267
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• 2016

To investigate the surface effects on vibration of embedded circular curved nanosize beams, nonlocal elasticity model is used in combination with surface properties including surface elasticity, surface tension and surface density for modeling the nano scale effect. The governing equations are determined via the energy method. Analytically Navier method is utilized to solve the governing equations for simply supported at both ends. Solving these equations enables us to estimate the natural frequency for circular curved nanobeam including Winkler and Pasternak elastic foundations. The results determined are verified by comparing the results by available ones in literature. The effects of various parameters such as nonlocal parameter, surface properties, Winkler and Pasternak elastic foundations and opening angle of circular curved nanobeam on the natural frequency are successfully studied. The results reveal that the natural frequency of circular curved nanobeam is significantly influenced by these effects.