• Proceedings of the KSME Conference
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• 2001.06a
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• pp.883-888
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The theoretical results are verified by comparison with FEM results.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.173-175
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• 1999

This paper deals with the rotor vibration analysis of Switched Reluctance Motor(SRM) with the 6/4 poles. For this analysis, 3-dimensional mode shapes corresponding to the natural frequency and critical speed map according to rotor speed are presented by using 3D Transfer Matrix Method(TMM). The gyroscopic effect and shear deformation of rotor are considered.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.4
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• pp.224-232
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• 1998

구조물에 손상이 발생하게 되면 동적특성이 변하게 된다. 그러므로 이와 같은 특성을 계측하여 구조물의 손상된 정도를 평가하게 되면 이를 상시감시에 활용할 수가 있다. 대표적인 손상기술들을 제작된 모형교량에 서로 다른 경계조건을 구현하여 손상도를 Simulation을 이용하여 결정하고 가장 적법한 방법과 대책을 연구했다. 모형교량은 I-DEAS의 Normal Mode Dynamic Solver를 이용하여 분석 제작되어 계측과 비교평가 되어 손상기술에 적용되었다. 24개의 가속도 감지기를 이용하여 데이터를 획득하였고, Residue법으로 모달인자를 추출하였다. 추출된 동적인자가 상시감시에 적용하도록 구조물의 손상검출기술을 제안한다

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.103-111
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• 1999

구조물에 손상이 발생하게 되면 동적특성이 변하게 된다. 그러므로 이와 갈은 특성을 계측하여 구조물의 손상된 정도를 평가하게 되면 이를 상시감시에 활용할 수가 있다. 대표적인 손상기술들을 제작된 모형교량에 서로 다른 경계조건을 구현하여 손상도를 Simulation을 이용하여 결정하고 가장 적법한 방법과 대책을 연구했다. 모형교량은 I-DEAS의 Normal Mode Dynamic Solver를 이용하여 분석 제작되어 계측과 비교평가 되어 손상기술에 적용되었다. 24개의 가속도 감지기를 이용하여 데이터를 획득하였고, Residue법으로 모달인자를 추출하였다. 추출된 동적인자가 상시감시에 적용하도록 구조물의 손상검출기술을 제안한다

• Journal of KSNVE
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• v.9 no.2
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• pp.348-354
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• 1999

An AC traction motor was developed, of which the rotor core has an unique structure, made of multi-layered silicon steel plates which were shrink-fitted to a shart. the equivalenet material properties were estimated with a newly proposed efficient method, based on the correlation between finite element analysis results and modal testing. A general rotordynamic analysis for the rotor with the equivalent material properties was carried out to evaluate the structural integrity of the virtually built-up motor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.4
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• pp.355-360
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• 2005

The objective of this study is design and structural analysis of 2nd crusher for useless wood. Structural analysis and modal analysis were effected in ANSYS and the structural safety was examined in search of displacement, stress, strain. There are avoid to resonance phenomenon by motor control.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.41-49
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• 1998

A nonlinear mathematical model of longitudinal combustion instability appropriate for ramjets and augmenters was developed based on modal analysis. The model was limited to a two-mode formulation. The associated differential equations were solved both analytically and numerically. The two-mode nonlinear model is capable of predicting the bootstrapping effect which characterizes nonlinear velocity-sensitive combustion response. Also, parametric studies were performed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.132-138
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• 2002

Of srategic importance nowdays is the development of high performance spacecraft bus. In this study, optimization for spacecraft structure is performed under the framework of coupled load analysis which is a branch of component mode synthesis with constrained mode and modal transient analysis. unlike the traditional method which uses the quasi-static table supplied by launch vehicle contractor, the present method adots the load results of previous coupled load analysis. It if shown that the proposed method can serve as a effective tool for the optimization spacecraft structure in the early stage of design and weight reduction by numerical example.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.356-364
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• 2000

Block based fast motion estimation algorithm use the fixed search pattern to reduce the search point, and are based on the assumption that the error in the mean absolute error space monotonically decreases to the global minimum. Therefore, in case of many local minima in a search region we are likely to find local minima instead of the global minimum and highly rely on the initial search points. This situation is evident in the motion boundary. In this paper we define the candidate regions within the search region using the motion information of the neighbor blocks and we propose the multiple local search method (MLSM) which search for the solution throughout the candidate regions to reduce the possibilities of isolation to the local minima. In the MLSM we mark the candidate region in the search point map and we avoid to search the candidate regions already visited to reduce the calculation. In the simulation results the proposed method shows more excellent results than that of other gradient based method especially in the search of motion boundary. Especially, in PSNR the proposed method obtains similar estimate accuracy with the significant reduction of search points to that of full search.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.135-144
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• 2016

It is essential to lighten the weight of switch girders in order to reduce their costs of manufacturing and make it easier to use them in construction. Lightening the weight of switch is also important to the Maglev 3-way switches system, however, the design variables should be considered very carefully if lightening is to be applied to the system, because these variables are vitally related to the levitation stability. Because Urban Maglev trains have a structure in which train bogie wraps around the guiderail, the adjustment of a girder's height is a possible way to reduce the weight. The safety of the application of this concept is ensured by repeated experiments in a test bed, however, due to a lack of space and budget limits, the design parametric study for the system model can substitute for actual application. The purpose of this paper is to study the design parameters that are concerned with levitation stability while a Maglev train is running on the Maglev 3-way system depending on the weight of the switch girders. In this study, switch girder weight is reduced by adjustment of girder height and girders are and modeled as a flexible body. The effect of the adjustment of girder height on the levitation stability can be analyzed by comparing the velocity of the train when it passes the switch girders, with the lateral gap, and the levitation gap which are obtained from the co-simulation of the Maglev train's dynamics model and flexible switching system. The results of this research will be used to design a Maglev switch.