• 한국공간구조학회논문집
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• 제4권4호
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• pp.99-111
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• 2004

An exact solution procedure is formulated for the free vibration and buckling analysis of rectangular plates having two opposite edges simply supported when these edges are subjected to linearly varying normal stresses. The other two edges may be clamped, simply supported or free, or they may be elastically supported. The transverse displacement (w) is assumed as sinusoidal in the direction of loading (x), and a power series is assumed in the lateral (y) direction (i.e., the method of Frobenius). Applying the boundary conditions yields the eigenvalue problem of finding the roots of a fourth order characteristic determinant. Care must be exercised to obtain adequate convergence for accurate vibration frequencies and buckling loads, as is demonstrated by two convergence tables. Some interesting and useful results for vibration frequencies and buckling loads, and their mode shapes, are presented for a variety of edge conditions and in-plane loadings, especially pure in-plane moments.

• Structural Engineering and Mechanics
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• 제12권6호
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• pp.669-684
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• 2001

A new method for solving the uncertain eigenvalue problems of the structures with interval parameters, interval finite element method based on the element, is presented in this paper. The calculations are done on the element basis, hence, the efforts are greatly reduced. In order to illustrate the accuracy of the method, a continuous beam system is given, the results obtained by it are compared with those obtained by Chen and Qiu (1994); in order to demonstrate that the proposed method provides safe bounds for the eigenfrequencies, an undamping spring-mass system, in which the exact interval bounds are known, is given, the results obtained by it are compared with those obtained by Qiu et al. (1999), where the exact interval bounds are given. The numerical results show that the proposed method is effective for estimating the eigenvalue bounds of structures with interval parameters.

• Structural Engineering and Mechanics
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• 제23권2호
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• pp.115-127
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• 2006

The axisymmetric free vibrations of transversely isotropic magnetoelectroelastic laminated circular plates are studied. Based on the three-dimensional governing equations of magnetoelectroelastic medium, the state space equations of laminated circular plates are obtained. By using the finite Hankel transform and rendering the free terms left by the transform in terms of the boundary quantities, the solutions of the state space equations are given for two kinds of boundary conditions. The frequency equations of the free vibration are derived using the propagator matrix method and the boundary conditions at top and bottom surfaces. By virtue of the inverse Hankel transform, the mode shapes are also determined. Since the solutions strictly satisfy the governing equations in the region and the boundary conditions at the edges, they are the three-dimensionally exact. Finally, the natural frequencies of such plates are tabulated and compared with those of the piezoelectric and elastic plates in the numerical example.

• 대한안전경영과학회지
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• 제3권2호
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• pp.133-144
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• 2001

This article deals with the multiple alternative proposal of Strategy. when Decision makers meet a very complex and important problems to take a good choice. It might not be easy that we make a decision and accept the decision as an exact result of analysis at a complication and uncertain situation. Although the decision under unpredictable state is many existence and each field is classified to support it. he can not provide exact estimations and be able to specify a result and forecasting. This is the reason why the original research use Statistical Survey method and Visual Decision Making Process(VDMP) to improve decision analysis method. Therefore, Our research suggests that the VDMP utilized in the strategic decision making situation as a group decision adding tool, can be applied in the development of a process vision and implementation plan. as a result, researcher describe step by step the process of VDMP.

• 한국산업정보학회논문지
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• 제19권5호
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• pp.1-7
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• 2014

거리 기반의 이동성 관리 방식은 무선 네트워크 연구 분야에서 주요한 주제로 고려되었다. 적당한 이동성 모델로 수학적으로 분석하기 위한 많은 연구가 진행되었다. 특히 양방향의 랜덤 워크 모델은 단순성의 장점으로 인하여 많이 활용되었다. 그럼에도 불구하고 정확한 수식에 의한 분석은 지금까지 아직 이루어지지 못하였다. 본 고에서 우리는 양방향 랜덤 워크모델에 관한 정확한 수식을 제공한다. 이러한 수학적 모델은 거리 기반의 이동성 관리 방식에 관한 연구에 많은 도움이 될 것으로 기대된다.

• 대한기계학회논문집
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• 제12권6호
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• pp.1438-1449
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• 1988

본 연구에서는 입자유동을 연속유체(continuous fluid)라 간주하는 2유체모델 을 적용하였고(Fig.2 참조), 실제 유동으로 2상난류제트유동, 관유동에 개발된 모델을 적용하여 모델의 타당성을 검토하였다.

• 한국정밀공학회지
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• 제20권6호
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• pp.197-204
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• 2003

This paper presents an efficient modeling and dynamic analysis method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the inconvenience and numerical errors in association with re-meshing the structural model with the crack position changed. The proposed modeling method is validated through a series of simulation and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, two kinds of experiments are performed to validate the proposed modeling method. Finally, a diagnostic scheme fur open cracked beam structures is proposed and demonstrated through a numerical example.

• 한국환경과학회지
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• 제8권5호
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• pp.555-558
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• 1999

A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 km, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind filed should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

• Journal of Communications and Networks
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• 제9권2호
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• pp.177-184
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• 2007

Alamouti space-time code (STC) is a part of the UMTS-WCDMA standard. However, up to the best of our knowledge no exact closed-form outage and bit error probability (BEP) formulas for this famous code exists. Evaluating its performance through simulations is time-consuming and therefore, there should be analytical performance graphs to serve as a reference which are derived in this paper for coherently MPSK-modulated data. Additionally, analytical results take into account different channel fading levels from transmit antennas to receive ones.

• 전기학회논문지
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• 제58권5호
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• pp.923-928
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• 2009

The performance analysis and robust control of the interior permanent magnet synchronous motor(IPMSM) greatly depend on accurate value of its parameters. To achieve the high performance of torque control, it is necessary to consider exact inductance values because the inductances are nonlinear parameters of operating the IPMSM. Therefore many different methods have been performed for analysis of the methodology for the exact measurement of synchronous inductances. None of them is considered standard, and accuracy levels of all these methods are also not consistent. Among these experimental methods, the DC current decay test and the vector current control test are ideal for a laboratory environment. In this paper, these two test methods are compared by applying inductances to the IPMSM. The paper analyzes the measured inductances of the two methods and their differences with inductances obtained from the finite element method(FEM).