• Structural Engineering and Mechanics
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• 제63권2호
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• pp.161-169
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• 2017

In this paper, using consistent couple stress theory and Hamilton's principle, the free vibration analysis of Euler-Bernoulli nano-beams made of bi-directional functionally graded materials (BDFGMs) with small scale effects are investigated. To the best of the researchers' knowledge, in the literature, there is no study carried out into consistent couple-stress theory for free vibration analysis of BDFGM nanostructures with arbitrary functions. In addition, in order to obtain small scale effects, the consistent couple-stress theory is also applied. These models can degenerate into the classical models if the material length scale parameter is taken to be zero. In this theory, the couple-tensor is skew-symmetric by adopting the skew-symmetric part of the rotation gradients as the curvature tensor. The material properties except Poisson's ratio are assumed to be graded in both axial and thickness directions, which it can vary according to an arbitrary function. The governing equations are obtained using the concept of Hamilton principle. Generalized differential quadrature method (GDQM) is used to solve the governing equations for various boundary conditions to obtain the natural frequencies of BDFG nano-beam. At the end, some numerical results are presented to study the effects of material length scale parameter, and inhomogeneity constant on natural frequency.

• 대한기계학회논문집A
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• 제20권4호
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• pp.1251-1262
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• 1996

In this paper, a mathematical model for a belt driven system is proposed to analyse the vibration characteristics of the driving units with belts and the free and forced vibraiton anlyses are carried out. The mathematical model for a belt-driven system includes belts, pulleys, spindle and bearings. By using Hamilton's principle, four nonlinear governing equations and twelve nonlinear boundary conditions are derived. To linearize and discretize the nonlinear governing equations and boundary conditions, the perturbation method and Galerkin method are used. Also, the free vibration analyses for various parameters of a belt driven system, which are the tension of a belt, the length of a belt, the material properties of belts, the velocity of a velt and the mass of pulley are made. The forced vibration analyses of the system are performed and the dynamic responses for main parameters are anlysed with a belt driven system.

• Smart Structures and Systems
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• 제30권2호
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• pp.121-133
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• 2022

An analytical approach for the free vibration behavior of a sandwich cylindrical shell with a functionally graded (FG) core is presented. It is considered that the FG distribution is in the direction of thickness. The material properties are temperature-dependent. The sandwich cylindrical shell with a FG core is considered with two cases. In the first model, i.e., Ceramic-FGM-Metal (CFM), the interior layer of the cylindrical shell is rich metal while the exterior layer is rich ceramic and the FG material is located between two layers and for the second model i.e., Metal-FGM-Ceramic (MFC), the material distribution is in reverse order. This study develops Carrera's Unified Formulation (CUF) to analyze sandwich cylindrical shell with an FG core for the first time. Considering the Principle of Virtual Displacements (PVDs) according to the CUF, the dependent boundary conditions and governing equations are obtained. The coupled governing equations are derived using Galerkin's method. In order to validate the present results, comparisons are made with the available solutions in the previous researches. The effects of different geometrical and material parameters on the free vibration behavior of a sandwich cylindrical shell with an FG core are examined.

• Steel and Composite Structures
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• 제51권4호
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• pp.457-471
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• 2024

In this research, for the first time the instability boundaries for a spinning shaft reinforced with graphene nanoplatelets undergone the principle parametric resonance are determined and examined taking into account the gyroscopic effect. In this respect, the extracted equations of motion in our previous research (Ref. Asadi et al. (2023)) are implemented and efficiently upgraded. In the upgraded discretized equations the effect of the Rayleigh's damping and the varying spinning speed is included that leads to a different dynamical discretized governing equations. The previous research was about the free vibration analysis of spinning graphene-based shafts examined by an eigen-value problem analysis; while, in the current research an advanced mechanical analysis is addressed in details for the first time that is the dynamics instability of the aforementioned shaft subjected to the principal parametric resonance. The spinning speed of the shaft is considered to be varied harmonically as a function of time. Rayleigh's damping effect is applied to the governing equations in order to regard the energy loss of the system. Resorting to Bolotin's route, Floquet theory and β-Newmark method, the instability region and its accompanied boundaries are defined. Accordingly, the effects of the graphene nanoplatelet on the instability region are elucidated.

• 한국언어정보학회지:언어와정보
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• 제14권1호
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• pp.145-163
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• 2010

This paper aims to propose that Benford's Law, non-uniform distribution of the leading digits in lists of numbers from many real-life sources, also appears in linguistic texts. The first digits in the frequency lists of morphemes from Sejong Morphologically Analyzed Corpora represent non-uniform distribution following Benford's Law, but showing complexity of numerical sources from complex systems like earthquakes. Benford's Law in texts is a principle reflecting regular distribution of low-frequency linguistic types, called LNRE(large number of rare events), and governing texts, corpora, or sample texts relatively independent of text sizes and the number of types. Although texts share a similar distribution pattern by Benford's Law, we can investigate non-uniform distribution slightly varied from text to text that provides useful applications to evaluate randomness of texts distribution focused on low-frequency types.

• Journal of Korea Trade
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• 제25권7호
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• pp.108-121
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• 2021

Purpose - This paper studies whether the CISG is applicable to the arbitration agreement when the validity of the arbitration agreement becomes an issue. To make the study clear, it limits the cases assuming that the governing law of the main contract is the CISG and the arbitration agreement is inserted in the main contract as a clause. Also, this paper discusses only substantive and formal validity of the arbitration agreement because the CISG does not cover the questions of the parties' capacity and arbitrability of the dispute. Design/methodology - This paper is based on scholarly writings and cases focusing on the principle of party autonomy, formation of contract and the doctrine of separability to discuss characteristic of arbitration agreement. In analyzing the cases, it concentrates on the facts and reasonings that show how the relative regulations and rules are interpreted and applied. Findings - The findings of this paper are; regarding substantive validity of arbitration agreement, the courts and arbitral tribunals consider general principles of law for the contract and the governing law for the main contract. In relation to formal validity of arbitration agreement, the law at the seat of arbitration or the law of the enforcing country are considered as the governing law in preference to the CISG because of the recognition and enforcement issues. Originality/value - This paper attempts to find the correlation between the CISG and the arbitration agreement. It studies scholars' writing and cases which have meaningful implication on this issue. By doing so, it can provide contracting parties and practitioners with some practical guidelines about the governing law for the arbitration agreement. Furthermore, it can help them to reduce unpredictability that they may confront regarding this issue in the future.

• 통상정보연구
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• 제11권1호
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• pp.309-331
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• 2009

In 25th April. 2008, the Korea legislature gave advance notice on the Revision Bill of Commercial Law in Insurance Division in partial, one of which is the principle of utmost good faith to be codified in accordance with the effectuation of the Revision Bill enforcement. For this, even though the disclosure duty is not included in the Revision Bill, it should also be discussed in relation to the principle of utmost good faith because it is based upon the principle of utmost good faith and forms a part of utmost good faith. In Marine Insurance industry in Korea, there are the sections and the clauses in relation to the English governing law included in the Policies and the Clauses used in Korea and, also, they still come into effect for the Korea Courts' judgements. So. we, Korea, should carefully pay attention to the trend of English courts' leading case, academic world and insurance industry on the disclosure duty in U.K. This study is thus based upon sections 17 and 18~20 of the Marine Insurance Act 1906 and sections 651, 652 and 655 of Commercial Law in Insurance Division, which appear throughout this work. The objective of this work is to analyse the duty of disclosure on Korean and English Insurance Laws including cases cited in this work, comparing the differences resulted from the analysis of the two countries‘laws and legal cases.

• 한국환경과학회지
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• 제23권1호
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• pp.113-128
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• 2014

Jeju Special Self-Governing Province has the natural assets resulting in UNESCO World Biosphere Reserve, World Heritage Listed and World Geopark Certification, so the principle of 'Conservation First Development Later' has been set up for the vision of environmental policy to preserve these assets. This case study has been carried out to investigate the realization of the principle of 'Conservation First Development Later' for the development projects performed environmental impact assessment from 1994 to 2012 in Jeju Province, using geographic information systems(GIS). The Jeju Province has its own ordinance to consult and operate an environmental impact assessment(EIA) system. In particular, the conservation area, such as, Absolute/Relative Conservation Area and Underground Water, Ecosystem and View Conservation Zone, has been assigned and managed specially to conserve the natural environment. The 179 projects has been performed EIA for last 18 years in Jeju Province, and then the Absolute Conservation Area has been included in 22 projects and the Relative Conservation Area has been included in 34 projects. However, the 2 projects only have included the Absolute Conservation Area for 7 years after 2005. This result suggests that the application of the principle for the Absolute Conservation Area is strengthened gradually. On the other hand, the 17 projects and the 24 projects have included the Underground Water Conservation Zone assigned grade 1 and 2, respectively, and the number has been increasing after 2004. The results show that it needs to strengthen the application of the principle for this Zone. And the Ecosystem Conservation Zone assigned grade 1 and 2 have been included in 1 project and 9 projects, respectively. It is considered from this result that the principle is realized successfully for the Ecosystem Conservation Zone. In addition, it could be known that the principle is applied well for the View Conservation Zone, in this study.

• 무역학회지
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• 제43권4호
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• pp.89-110
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• 2018

본 연구는 신용장거래에서 은행의 독립지급의무 및 이 의무에 대한 예외적인 취급원칙과 방향에 대한 문제를 소재로 취급하였다. 독립원칙과 독립원칙에 대한 예외문제는 신용장의 본질에 관계되지만 국가마다 이러한 문제를 취급하는 태도에 차이가 존재한다. 본 연구에서는 영국에서의 태도를 분석하기 위해 독립원칙과 예외문제를 취급한 판례 중에서 지도적인 판례로 인정되는 사례를 중심으로 하여 독립원칙과 예외문제를 취급하는 영국의 입장을 분석하였다. 영국법원은 가능한 한 상인들 간에 형성되어 온 상관습을 존중하려는 입장을 취해 왔으며 독립원칙의 실무적인 적용에 있어서도 이러한 입장을 반영하여 독립원칙의 중요성을 강조하면서도 실질적으로는 개개의 사안마다 당사자의 형평을 고려하여 예외문제를 취급하여 왔다. 그러나 미국의 Sztejn 사건을 계기로 하여 영국에서도 독립원칙의 적용에 대한 태도의 변화를 보여 신용장거래에서의 사기뿐만이 아니라 기초계약에서의 사기도 독립지급의무에 대한 예외사유로서 인정하기 시작하였다. 그렇지만 독립원칙에 대한 예외의 운영방식에 따라 신용장제도의 존재의의가 상실될 우려가 있고 또한 발행의뢰인에 의해서 예외적용을 남용할 가능성도 있다는 문제점들을 감안하여 영국은 비록 사기적인 요소가 존재하지만 수익자 자신이 선의의 입장에 있는 경우에는 수익자를 보호하는 입장을 채택함으로써 예외인정과 예외의 남용문제 간의 조정을 도모하고 있다.

• Structural Engineering and Mechanics
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• 제57권4호
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• pp.733-762
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• 2016

Based on a reduced displacement field, a layer-wise (LW) formulation is developed for analysis of thick shell panels which is subjected to axial tension. Employing the principle of minimum total potential energy, the local governing equations of thick panel which is subjected to axial extension are obtained. An analytical method is developed for solution of the governing equations for various edge conditions. The governing equations are solved for free and simply supported edge conditions. The interlaminar stresses in the panel are investigated by means of Hooke's law and also by means of integration of the equilibrium equations of elasticity. Dependency of the result upon the number of numerical layers in the layerwise theory (LWT) is studied. The accuracy of the numerical results is validated by comparison with the results of the finite element method and with other available results in the open literature and good agreement is seen between the results. Numerical results are then presented for the distribution of interlaminar normal and shear stresses within the symmetric and un-symmetric cross-ply thick panels with free and simply supported boundaries. The effects of the geometrical parameters such as radius to thickness and width to thickness ratio are investigated on the distribution of the interlaminar stresses in thick panels.