• Coupled systems mechanics
• /
• 제7권6호
• /
• pp.649-668
• /
• 2018

In this paper, we present a numerical model for fluid-structure interaction between structure built of porous media and acoustic fluid, which provides both pore pressure inside porous media and hydrodynamic pressures and hydrodynamic forces exerted on the upstream face of the structure in an unified manner and simplifies fluid-structure interaction problems. The first original feature of the proposed model concerns the structure built of saturated porous medium whose response is obtained with coupled discrete beam lattice model, which is based on Voronoi cell representation with cohesive links as linear elastic Timoshenko beam finite elements. The motion of the pore fluid is governed by Darcy's law, and the coupling between the solid phase and the pore fluid is introduced in the model through Biot's porous media theory. The pore pressure field is discretized with CST (Constant Strain Triangle) finite elements, which coincide with Delaunay triangles. By exploiting Hammer quadrature rule for numerical integration on CST elements, and duality property between Voronoi diagram and Delaunay triangulation, the numerical implementation of the coupling results with an additional pore pressure degree of freedom placed at each node of a Timoshenko beam finite element. The second original point of the model concerns the motion of the outside fluid which is modeled with mixed displacement/pressure based formulation. The chosen finite element representations of the structure response and the outside fluid motion ensures for the structure and fluid finite elements to be connected directly at the common nodes at the fluid-structure interface, because they share both the displacement and the pressure degrees of freedom. Numerical simulations presented in this paper show an excellent agreement between the numerically obtained results and the analytical solutions.

• 한국중재학회지:중재연구
• /
• 제27권1호
• /
• pp.85-106
• /
• 2017

This article deals with the relationship between arbitration and state court in each procedural stage. As most legal systems over the world respect arbitration agreement, the relationship between arbitration and state courts puts emphasis on party autonomy and provides the independent power of arbitration agreement tribunal (Kompetenz-Kompetenz). Most institutional arbitration rules the arbitral tribunal to rule on its own jurisdiction. Modern national laws have similar provisions based on Art. 16 UNCITRAL Model Law. In this regards the author throws a question in Chapter II, whether the doctrine of Kompetenz-Kompetenz, namely the ability of the tribunal to decide upon its own jurisdiction is worth while persisting, and whether the Kompetenz-Kompetenz-agreement should be regarded as valid, with the conclusion, that this doctrine should concede to the power of state court and that Kompetenz-Kompetenz-Klausel is invalid. In Chapter III the author discusses the issue of whether the breach of an arbitration agreement could lead to the compensation of damage. Although the author stands for the procedural character of arbitration agreement, he offers a proposal that the breach of an arbitration agreement bring about the compensation of damage. The issue of anti-suit injunction is discussed also in this Chapter. He is against the approval of anti-suit injunction based on an arbitration agreement resisting the other party from pursuing a lawsuit in a foreign country.

• 한국항공운항학회지
• /
• 제25권3호
• /
• pp.123-134
• /
• 2017

In order to advance into the MRO industry, the Aviation maintenance organization with suitable for the standards for personnel, facilities and operations should be first approved by FAA and EASA. The purpose of study is designed to arrange the standards required for personnel, facility, operation rule for approval of Repair Station maintenance organizations certified by FAA PART 145 of the US Federal Aviation Regulation. Also to consider the following differences through the comparative analysis with domestic AMO certification of the information in the Management, Maintenance Process, and Quality System for approval of maintenance organization authorized, the additional EASA PART 145. As a comparative analysis on maintenance organization certification in the country between FAA and EASA, this study could show us that domestic maintenance organization, certified manual contents are used by applying just many of the FAA system. And we could know that as part of the EASA maintenance organization certification process, airmen personnel were relatively systematically segmented and controlled. For domestic maintenance organization certification, operational as policy implications we would like to present policy implications such as the implication of rating system of Aviation Mechanic License like EASA, the financial support of the training center to resolve the shortage of the FAA or EASA license holders, operational organization as "CAMO" for systematic aviation mechanic certified system should be required, continued construction of hangar or MRO for airworthiness repair under Governmental support, and varied application of DER system from FAA accordingly.

• Advances in nano research
• /
• 제7권4호
• /
• pp.249-263
• /
• 2019

In the current paper, an exact solution method is carried out for analyzing the thermo-mechanical vibration of curved FG nano-beams subjected to uniform thermal environmental conditions, by considering porosity distribution via nonlocal strain gradient beam theory for the first time. Nonlocal strain gradient elasticity theory is adopted to consider the size effects in which the stress for not only the nonlocal stress field but also the strain gradients stress field is considered. It is perceived that during manufacturing of functionally graded materials (FGMs) porosities and micro-voids can be occurred inside the material. Material properties of curved porous FG nanobeam are assumed to be temperature-dependent and are supposed to vary through the thickness direction of beam which modeled via modified power-law rule. Since variation of pores along the thickness direction influences the mechanical and physical properties, porosity play a key role in the mechanical response of curved FG nano-structures. The governing equations and related boundary condition of curved porous FG nanobeam under temperature field are derived via the energy method based on Timoshenko beam theory. An analytical Navier solution procedure is utilized to achieve the natural frequencies of porous FG curved nanobeam supposed to thermal loading. The results for simpler states are confirmed with known data in the literature. The effects of various parameters such as nonlocality parameter, porosity volume fractions, thermal effect, gradient index, opening angle and aspect ratio on the natural frequency of curved FG porous nanobeam are successfully discussed. It is concluded that these parameters play key roles on the dynamic behavior of porous FG curved nanobeam. Presented numerical results can serve as benchmarks for future analyses of curve FG nanobeam with porosity phases.

• Advances in materials Research
• /
• 제5권4호
• /
• pp.279-298
• /
• 2016

Present disquisition proposes an analytical solution method for exploring the buckling characteristics of porous magneto-electro-elastic functionally graded (MEE-FG) plates with various boundary conditions for the first time. Magneto electro mechanical properties of FGM plate are supposed to change through the thickness direction of plate. The rule of power-law is modified to consider influence of porosity according to two types of distribution namely even and uneven. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM plate under magneto-electrical field via Hamilton's principle. An analytical solution procedure is exploited to achieve the non-dimensional buckling load of porous FG plate exposed to magneto-electrical field with various boundary condition. A parametric study is led to assess the efficacy of material graduation exponent, coefficient of porosity, porosity distribution, magnetic potential, electric voltage, boundary conditions, aspect ratio and side-to-thickness ratio on the non-dimensional buckling load of the plate made of magneto electro elastic FG materials with porosities. It is concluded that these parameters play remarkable roles on the dynamic behavior of porous MEE-FG plates. The results for simpler states are confirmed with known data in the literature. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

• International Journal of Advanced Culture Technology
• /
• 제8권2호
• /
• pp.96-100
• /
• 2020

In this paper, I try to help the business operation so that they could continue the desirable operation despite the unfavorable conditions. It is important to reinforce for corporate growth various support measures to generate profits. However, if they are involved in criminal activities such as slush fund creation, they will have to deal with them separately. As a result, To raise awareness helps to keep the company running. Recently, the companies are in a poor condition due to overseas migration. If a company does not create profits by doing business, it is a burden to continue operating and it will eventually be hard to support and destroy. The corporate crime and white-collar crime are mostly similar types, mainly because they occur in the industry. The corporate crime proceeds throughout the company and ultimately translates into corporate profits. The white-collar crime, on the other hand, is a profitable part of the individual. In the process of generating profits, the purpose and management method of slush funds is an important issue in judging whether illegal immorality of business is intended or not. In addition, in the case of the corporate crime, it seems necessary to identify the types of slush fund raising activities in addition to the investigations of the accomplices and clinical investigations, and to apply efficient investigation methods on a case-by-case basis. At present, many companies frequently migrate overseas due to the influence of domestic regulations. In this process, if it is involved in crime such as a borrowing accounts or the purpose of slush fund creation should be treated separately.

• Journal of Power Electronics
• /
• 제15권3호
• /
• pp.753-762
• /
• 2015

This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method.

• Advances in nano research
• /
• 제8권1호
• /
• pp.83-94
• /
• 2020

An analytical formulation and solution process for the buckling analysis of porous magneto-electro-elastic functionally graded (MEE-FG) beam via different thermal loadings and various boundary conditions is suggested in this paper. Magneto electro mechanical coupling properties of FGM beam are taken to vary via the thickness direction of beam. The rule of power-law is changed to consider inclusion of porosity according to even and uneven distribution. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. Change in pores along the thickness direction stimulates the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM beam under magneto-electrical field via Hamilton's principle. An analytical model procedure is adopted to achieve the non-dimensional buckling load of porous FG beam exposed to magneto-electrical field with various boundary conditions. In order to evaluate the influence of thermal loadings, material graduation exponent, coefficient of porosity, porosity distribution, magnetic potential, electric voltage and boundary conditions on the critical buckling temperature of the beam made of magneto electro elastic FG materials with porosities a parametric study is presented. It is concluded that these parameters play remarkable roles on the buckling behavior of porous MEE-FG beam. The results for simpler states are proved for exactness with known data in the literature. The proposed numerical results can serve as benchmarks for future analyses of MEE-FG beam with porosity phases.

• Journal of Korea Trade
• /
• 제24권7호
• /
• pp.73-92
• /
• 2020

Purpose - The letter of credit has been playing a major role to diminish overall risks which exist among concerned parties even though there are differences such as language, culture, law, and distance. This paper reviews essence of the letter of credit and its transaction principles, as well as overall practical questions based on the L/C transaction principle. It also investigates the risk of fraud occurrences in L/C transactions and the importance of fraud prevention and preventive measures in international L/C transactions, including the Fraud Rule, which is a major topic to consider in business transactions. Design/methodology - It is considered that an importing country's concerned parties and an exporting country's concerned parties face different situations. This study employs the existing framework to identify liability, responsibility, and obligation for all concerned parties across countries. Using a quite direct measurement of principles in the letter of credit, such as principle of independence, principle of abstraction, and principle of strictness and coincidence, we studied these differences. Findings - Our main findings can be summarized as follow. The paper enhances the efficiency of the L/C payment method to provide fraud generated from L/C transactions, presentation of a theoretical framework about fraud and fraud prevention, which international trading companies should acknowledge in a material way based on fraud risk resulting from taking advantage of L/C transaction principles. Originality/value - Existing studies focus on fraud accidents in L/C transactions by taking bad advantage of the characteristics of the letter of credit without suggesting risks of fraud. This paper attempts to evaluate and provide preventive measures as a solution for fraud and risky international business in a letter of credit transaction. This area of trade studies is underexplored, both empirically and theoretically, although the issue has long been important to Korean and world community foreign trade.

• Structural Engineering and Mechanics
• /
• 제72권1호
• /
• pp.113-129
• /
• 2019

A four-variable shear deformation refined plate theory has been proposed for dynamic characteristics of smart plates made of porous magneto-electro-elastic functionally graded (MEE-FG) materials with various boundary conditions by using an analytical method. Magneto-electro-elastic properties of FGM plate are supposed to vary through the thickness direction and are estimated through the modified power-law rule in which the porosities with even and uneven type are approximated. Pores possibly occur inside functionally graded materials (FGMs) due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical properties. The governing differential equations and boundary conditions of embedded porous FGM plate under magneto-electrical field are derived through Hamilton's principle based on a four-variable tangential-exponential refined theory which avoids the use of shear correction factors. An analytical solution procedure is used to achieve the natural frequencies of embedded porous FG plate supposed to magneto-electrical field with various boundary condition. A parametric study is led to carry out the effects of material graduation exponent, coefficient of porosity, magnetic potential, electric voltage, elastic foundation parameters, various boundary conditions and plate side-to-thickness ratio on natural frequencies of the porous MEE-FG plate. It is concluded that these parameters play significant roles on the dynamic behavior of porous MEE-FG plates. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.