• Steel and Composite Structures
• /
• v.26 no.4
• /
• pp.421-437
• /
• 2018

Free vibration analysis of a three-layered microbeam including an elastic micro-core and two piezo-magnetic face-sheets resting on Pasternak's foundation are studied in this paper. Strain gradient theory is used for size-dependent modeling of microbeam. In addition, three-unknown shear and normal deformations theory is employed for description of displacement field. Hamilton's principle is used for derivation of the governing equations of motion in electro-magneto-mechanical loads. Three micro-length-scale parameters based on strain gradient theory are employed for prediction of vibrational characteristics of structure in micro-scale. The results show that increase of three micro-length-scale parameters leads to significant increase of three natural frequencies especially for increase of second micro-length-scale parameter. This result is according to this fact that stiffness of a micro-scale structure is increased with increase of micro-length-scale parameters.

• Journal of the Korean Applied Science and Technology
• /
• v.27 no.4
• /
• pp.452-460
• /
• 2010

Any theory of liquid should account for interactions between molecules, since molecules in a liquid are close to each other. For this matter statistical-mechanical methodology has been used and various models have been proposed on the basis of this methodology. Among them Kirkwood-Buff solution theory has attracted a lot of interest, because it is regarded as being the most powerful. In this article Kirkwood-Buff solution theory is revisited and its key equations are derived. On the way to these equations, the concepts of pair correlation function, radial distribution function, Kirkwood-Buff integration are explained and implemented. Since complexity of statical mechanics involved in this theory, the equations are applied to one-component systems and the results are compared to those obtained by classical thermodynamics. This may be a simple way for Kirkwood-Buff solution theory to be examined for its validity.

• Journal of the Korean Wood Science and Technology
• /
• v.28 no.4
• /
• pp.72-82
• /
• 2000

Attempts were made to analyze the behavior of single and multiple-bolted connections through theoretical methods such as European yield theory, empirical approaching method, and semi-rigid theory instead of many experimental methods that have been actually inefficient and non-economical. In the case of a single-bolted connection, if accurate characteristic values of a material could be guaranteed, it would be more convenient and economical to perform the behavior analysis using a model based on the semi-rigid theory, instead of the existing complex yield model, or the empirical formula which produces errors, giving different results from the actual ones. If the variables of equation determining the load and deformation could be appropriately controlled, the analytical method in conjunction with a semi-rigid theory could be effectively applied to obtain the desirably predicted value, considering that the appropriate solution could be derived through a simpler equation using a less difficult method compared to the existing yield model. It is concluded that analytical method with semi-rigid theory can be used in the behavior analysis of bolted connection because our developed method showed excellent analysis ability of behavior until number of bolt is two. Although our analytical method has the disadvantage that the number of bolt is limited to two, it is concluded that it has the advantage than numerical method which complicated and time-consuming.

• Structural Engineering and Mechanics
• /
• v.55 no.5
• /
• pp.1001-1014
• /
• 2015

Bending analysis of functionally graded (FG) nano-plates is investigated in the present work based on a new sinusoidal shear deformation theory. The theory accounts for sinusoidal distribution of transverse shear stress, and satisfies the free transverse shear stress conditions on the top and bottom surfaces of the plate without using shear correction factor. The material properties of nano-plate are assumed to vary according to power law distribution of the volume fraction of the constituents. The size effects are considered based on Eringen's nonlocal theory. Governing equations are derived using energy method and Hamilton's principle. The closed-form solutions of simply supported nano-plates are obtained and the results are compared with those of first-order shear deformation theory and higher-order shear deformation theory. The effects of different parameters such as nano-plate length and thickness, elastic foundation, orientation of foundation orthtotropy direction and nonlocal parameters are shown in dimensionless displacement of system. It can be found that with increasing nonlocal parameter, the dimensionless displacement of nano-plate increases.

• Structural Engineering and Mechanics
• /
• v.62 no.5
• /
• pp.607-618
• /
• 2017

In this paper, an analytical procedure based on the perturbation technique is presented to study the free vibrations of annular viscoelastic plates by considering the first order shear deformation theory as the displacement field. The viscoelastic properties obey the standard linear solid model. The equations of motion are extracted for small deflection assumption using the Hamilton's principle. These equations which are a system of partial differential equations with variable coefficients are solved analytically with the perturbation technique. By using a new variable change, the governing equations are converted to equations with constant coefficients which have the analytical solution and they are appropriate especially to study the sensitivity analysis. Also the natural frequencies are calculated using the classical plate theory and finite elements method. A parametric study is performed and the effects of geometry, material and boundary conditions are investigated on the vibrational behavior of the plate. The results show that the first order shear deformation theory results is more closer than to the finite elements with respect to the classical plate theory for viscoelastic plate. The more results are summarized in conclusion section.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.27 no.2
• /
• pp.51-63
• /
• 2014

Objectives : Reaserch on ophthalmology drawings in Euibangyoochui reveals the medical historic flows of the theory of ohryun-palgwak that is representative theory of ophthalmology. Methods : Ophthalmology drawings are divided into ohryun-palgwak drawings and eye disease drawings. Four picture of ophthalmology drawings in Euibangyoochui are shown in the books of suwolnobangyung, seeuidekhyobang, suyeoksinbang. Results : Ohryun drawing which describes the relationship between eyes and five viscera mentioned in lingshu. This is based on the theory of five elements. Palgwak drawing shows the combination palgwak theory and the eight trigrams of iching. Conclusions : In Korean Medicine theory of the eye, the diagnosis of eyes could be diagnosed eye disease and diseases of five viscera and six entrails. Each parts of the eye are reflected disorders in the five viscera and six entrails. Ophthalmology drawings in Euibangyoochui explains well these theories.

• Korean System Dynamics Review
• /
• v.8 no.1
• /
• pp.5-24
• /
• 2007

This study explores the partnership between government and human service nonprofits in the United States from the perspective of resource dependence theory and extends the theory with system dynamics in order to better explain government-nonprofit service delivery. The article is structured as follows. First, I introduce the historical development of the government-nonprofit partnership in service delivery in the United States. Second, I present an overview of resource dependence theory for government-nonprofit service delivery, including assumptions, key elements, claims, how well it explains the government-nonprofit service delivery, and limitations. Third, I highlight the advantages of system dynamics along with the limitations of resource dependence theory, as an attempt to revise the theory. Finally, I conclude with a summary and suggestions for the next steps in theoretical development and research.

• Journal of architectural history
• /
• v.3 no.2 s.6
• /
• pp.125-141
• /
• 1994

Alois Riegl's aesthetic theory of visual perception provided one of important conceptual backgrounds for Vienna Art Nouveau architecture. Riegls theory of visual perception consists of geometric style and two-dimensional transformation. Riegl's theory of geometric style is based on the modern aesthetic theory of abstraction, which says that the artistic perfection can be obtained not from a direct imitation of natural objects, but from an abstract transformation of them. Riegl's theory of two-dimensional transformation, on the other hand, aims at obtaining artistic perfection by disintegrating volumetric conditions of natural things into planes and combining the planes thus obtained into another new world of art. These two theories of Alois Rigl's provided an important aesthetical background for the design strategy of 'abstract ornamentaion of two-dimension' in Vienna Art Nouveau architecture. This paper is to review the basic concept of Alois Rigl's theory of geometric style and two-dimensional transformation.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.277-279
• /
• 2003

Theory calculation way because verification is lacking, we compare and analyzed with calculation theory value and experiment value that is noted through a water tank model experiment based on connection theory way that is announced in existing.

• Communications of Mathematical Education
• /
• v.19 no.4 s.24
• /
• pp.599-620
• /
• 2005

There can be two different approaches to introducing Abstract Algebra to undergraduate students: One is to introduce group concept prior to ring concept, and the other is to do the other way around. Although the former is almost conventional, it is worth while to take the latter into consideration in the viewpoint that students are already familiar to rings of integers and polynomials. In this paper, we investigated 16 most commonly used Abstract Algebra undergraduate textbooks and found that 5 of them introduce ring theory prior to group theory while the rest do the other way around. In addition, we interviewed several undergraduate students who already have taken an Abstract Algebra course to look into which approach they prefer. Then we compare pros and cons of two approaches on the basis of the results of the interview and the historico-genetic principle of teaching and learning in Abstract Algebra and suggest that it certainly be one of alternatives to introduce ring theory before group theory in its standpoint.