• Coupled systems mechanics
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• 제13권1호
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• pp.43-60
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• 2024

This work presents an analytical approach to investigate wave propagation in bi-directional functionally graded cantilever porous beam. The formulations are based on Touratier's higher-order shear deformation beam theory. The physical properties of the porous functionally graded material beam are graded through the width and thickness using a power law distribution. Two porosities models approximating the even and uneven porosity distributions are considered. The governing equations of the wave propagation in the porous functionally graded beam are derived by employing the Hamilton's principle. Closed-form solutions for various parameters and porosity types are obtained, and the numerical results are compared with those available in the literature.The numerical results show the power law index, number of wave, geometrical parameters and porosity distribution models affect the dynamic of the FG beam significantly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.135-137
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• 1992

A new algorithm for self-tuning digital controller is proposed. The system to be controlled is identified on line in auto-regressive-moving-average(ARMA) form via recursive least mean square method. The control law is obtained from the minimization of an objective function. The proposed objective function is similar to that of Generalized Minimum Variance(GMV) method but modified to lessen the overshoot and to avoid numerical divergence problem. This algorithm is applied to the power system stabilization and the comparison of the proposed method with a conventional power system stabilizer(PSS) is presented.

• 한국중재학회지:중재연구
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• 제17권1호
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• pp.57-75
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• 2007

Ever since franchising emerged in the industry of distribution, it has been growing explosively in the U.S.A. and all other countries as well. It is a method of expanding a business by licensing independent businessman to sell the franchiser's products and/or services or to follow a format and trade style created by the franchiser using the franchiser's trade marks and trade names. Franchising is a form of business that touches upon many different areas of law including, but not limited to, general contract law, general principles of commercial law, law of intellectual property, competition law, fair trade practices law and other industry specific laws e.g., the Fair Practices in Franchising Act in Korea. Arbitration is a long established, legally recognized procedure for submitting disputes to an outside person(s), mutually selected by the parties, for a final and binding decision. Despite its merits as an alternative dispute resolution, it has been criticized, on the other hand, particularly by franchisees' attorneys on the ground that even though it is required to protect the franchisees against the enforcement of pre-dispute arbitration agreements because of the franchisees' paucity of bargaining power vis-a-vis the franchiser, arbitration cannot afford it. Until recently, however, little has been written about the legal issues pertaining to franchise agreement and arbitration clause contained therein in Korea. This treatise reviews the cases and arguments in relation to the subject especially of the U.S.A., which have been accumulated for decades. The issues addressed herein are the pre-emption by the FAA, the disputes to be arbitrated, the selection and qualification of arbitrators, the place of arbitration hearings and the evidentiary rules applicable, the expenses of arbitration, theory of fiduciary duty and the like, all of which are relevant to franchise agreement.

• Advances in concrete construction
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• 제13권5호
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• pp.367-376
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• 2022

Theoretical study of vibration distinctiveness of rotating cylindrical are examined for three volume fraction laws viz.: polynomial, exponential and trigonometric. These laws control functionally graded material composition in the shell radius direction. Functionally graded materials are controlled from two or more materials. In practice functionally graded material comprised of two constituent materials is used to form a cylindrical shell. For the current shell problem stainless steel and nickel are used for the shell structure. A functionally graded cylindrical shell is sanctioned into two types by interchanging order of constituent materials from inner and outer side for Type I and Type II cylindrical shell arrangement. Fabric composition of a functionally graded material in a shell thickness direction is controlled by volume fraction law. Variation of power law exponent brings change in frequency values. Influence of this physical change is investigated to evade future complications. This procedure is capable to cater any boundary condition by changing the axial wave number. But for simplicity, numerical results have been evaluated for clamped- simply supported rotating cylindrical shells. It has been observed from these results that shell frequency is bifurcated into two parts: one is related to the backward wave and other with forward wave. It is concluded that the value of backward frequency is some bit higher than that forward frequency. Influence of volume fraction laws have been examined on shell frequencies. Backward and forward frequency curves for a volume fraction law are upper than those related to two other volume fraction laws. The results generated furnish the evidence regarding applicability of present shell model and also verified by earlier published literature.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.460-465
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• 2013

Electrical equipments of nuclear power plant are divided into class 1E and non-class 1E. Electrical equipment and systems that are essential to emergency reactor shutdown, containment isolation, reactor core cooling, and containment and reactor heat removal, are classified as class 1E. batteries of nuclear power plant are divided into four channels, which are physically and electrically separate and independent. The battery bank of class 1E DC power system of the nuclear power plant use lead-acid batteries in present. The lead acid battery, which has a high energy density, is the most popular form of energy storage. Kt factor of lead-acid battery is used to determine battery size and it is one of calculatiing coefficient for capacity. this paper analyzes Kt factor of lead-acid battery for the DC power system of nuclear power plant. In addition, correlation between Kt parameter and peukert's exponent of lead-acid battery for nuclear plant are discussed. The analytical results contribute to optimize of determining size Lead-acid battery bank.

• Structural Engineering and Mechanics
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• 제40권4호
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• pp.583-594
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• 2011

In the present study, free vibration of an axially functionally graded (AFG) pile embedded in Winkler-Pasternak elastic foundation is analyzed within the framework of the Euler-Bernoulli beam theory. The material properties of the pile vary continuously in the axial direction according to the power-law form. The frequency equation is obtained by using Lagrange's equations. The unknown functions denoting the transverse deflections of the AFG pile is expressed in modal form. In this study, the effects of material variations, the parameters of the elastic foundation on the fundamental frequencies are examined. It is believed that the tabulated results will be a reference with which other researchers can compare their results.

• Structural Engineering and Mechanics
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• 제62권3호
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• pp.311-324
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• 2017

In this paper a new eight-unknown higher order shear deformation theory is proposed for functionally graded (FG) material plates. The theory based on full twelve-unknown higher order shear deformation theory, simultaneously satisfy zeros transverse stresses at top and bottom surface of FG plates. Equations of motion are derived from principle of virtual displacement. Exact closed-form solutions are obtained for simply supported rectangular FG plates under uniform loading. The accuracy of present numerical results has been verified by comparing it with generalized shear deformation theory. The effect of power law index of functionally graded material, side-to-thickness ratio, and aspect ratio on static behavior of FG plates is investigated.

• Steel and Composite Structures
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• 제43권2호
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• pp.185-200
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• 2022

A Closed-form solution for dynamic response of a functionally graded (FG) nonlocal nanobeam due to action of moving harmonic load is presented in this paper. Due to analyzing in small scale, a nonlocal elasticity theory is utilized. The governing equation and boundary conditions are derived based on the Euler-Bernoulli beam theory and Hamilton's principle. The material properties vary through the thickness direction. The harmonic moving load is modeled by Delta function and the FG nanobeam is simply supported. Using the Laplace transform the dynamic response is obtained. The effect of important parameters such as excitation frequency, the velocity of the moving load, the power index law of FG material and the nonlocal parameter is analyzed. To validate, the results were compared with previous literature, which showed an excellent agreement.

• 융합보안논문지
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• 제11권5호
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• pp.41-51
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• 2011

이 연구는 우리나라 경비업 현황분석을 통하여 현재 경비업의 개괄적 실태를 살펴본 후, 경비업법 개정과정 분석을 통하여 어떠한 정책기조가 법 개정에 투영되었는가를 도출한 다음, 우리나라 시큐리티산업의 정책방향을 제안하는데 연구의 목적을 두고 있다. 경비업법 개정 과정을 통하여 보면 공공성 강화와 기업성 강화가 어떤 뚜렷한 정책적 기조를 이루고 있는 것으로 보이진 않는다. 다만 강력한 공공성의 기조하에 부분적으로 기업성을 일부 반영한 것으로 밖에 해석되지 않는 것이다. 경비업의 건전한 발전을 위해서는 기존의 정책 방향에서 탈피하여 경비업의 기업성을 강화하는 방향으로 정책 기조가 변화되어야 한다. 경찰의 지도 감독 권한을 한국경비협회에 대폭 이관하여 경비업계의 자율적인 정화 기능을 키워야 한다. 경찰에서는 치안서비스의 공동생산 차원에서의 정책 개발에 관심을 두고 지혜를 모아야 할 것이다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1324-1335
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• 2016

This article explores the speed regulation problem of permanent magnet synchronous motor (PMSM) systems subjected to unknown time-varying disturbances. A continuous sliding mode control (CSMC) technique is introduced for the speed loop to enhance the robustness of PMSM systems and eliminate the chattering phenomenon caused by high-frequency switch function in the conventional control law. However, the high control gain of the CSMC law in the presence of strong disturbances leads to large steady-state speed fluctuations for PMSM systems. In many application fields, PMSM systems are affected by time-varying disturbances instead of constant disturbances. For example, electric bicycles are usually affected by changing environmental disturbances, including wind speeds, road conditions, etc. These disturbances may be in the form of constant, ramp, and parabolic disturbances. Hence, a generalized proportional integral (GPI) observer is employed to estimate these types of disturbances. Then, the disturbance estimation method and the aforementioned CSMC method are combined to establish a composite sliding mode control method called the CSMC+GPI method for the speed loop of PMSM systems. Contrary to the conventional sliding mode control technique, the proposed method completely eliminates the chattering phenomenon caused by the switching function in the conventional control law. Moreover, a small control gain for the CSMC+GPI method is chosen by feed-forwarding estimated values to the speed controller. Hence, the steady-state speed fluctuations are small. The effectiveness of the proposed control scheme is verified by simulation and experimental result.