• 한국소음진동공학회논문집
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• 제22권8호
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• pp.777-783
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• 2012

진동 인텐시티는 진동시스템에서 진동원의 위치를 찾는데 사용되어 왔다. 벡터 표현법 사용에 의해 파워흐름의 원인과 진동에너지 전달경로가 밝혀질 수 있다. 그러나, 판과 같은 구조물의 넓은 면적으로 인해 벡터 가시화를 사용하여 명확한 전달경로를 알아낼 수 없었다. 실험적으로 큰 면적의 물체에서는 측정점의 수가 늘어나게 된다. 이것은 측정에 많은 시간이 요구된다. 이번 연구에서는 FEM과 실험에 의한 모든 면에서 파워흐름 전달경로를 분명하게 가리키기 위해 유선 표현법이 사용되었다. 진동 인텐시티 전달경로를 분명하게 향상시키기 위해 실험과 FEM으로부터의 유선 표현을 비교하였다. 또한 FEM과 실험의 개선된 전달경로 가시화를 기존의 벡터표현과 비교하였다. 이 유선 가시화는 큰 표면을 갖는 판과 같은 구조물에 대해 진동원과 상세한 에너지 전달경로를 확인하는데 유용하다. 그 뿐만 아니라, 이 가시화 방법은 실험과 FEM 해석에 대해 많은 측정점을 필요로 하지 않는다.

• 한국구조물진단유지관리공학회 논문집
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• 제20권1호
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• pp.85-94
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• 2016

본 연구에서는 요철형 이음단면을 갖는 프리캐스트 교량 바닥판 이음부의 정적 휨성능을 예측하기 위한 비선형 유한요소해석 모델을 구성하였으며, 선행연구에 의한 실험결과와의 비교를 통해 유한요소해석의 적합성을 확인하였다. 유한요소해석 모델을 구성하는 재료특성으로 각각의 이론을 적용하였으며, 실험결과 및 사전 변수해석을 통해 입력변수들을 결정하여 유한요소해석 모델을 구성하였다. 본 연구에서 수행된 유한요소해석 결과는 각각의 실험체에 대한 구조적 거동을 평균 5% 이내로 비교적 정확하게 추정하는 것으로 나타났으며, 소성 변형률 분포로부터 각 실험체의 균열양상 및 파괴형태를 간접적으로 예측할 수 있었다. 따라서 본 연구에서 사용된 유한요소해석 모델은 향후 프리캐스트 바닥판 이음부의 극한거동 예측 및 이음부의 설계식 도출을 위한 변수해석 연구 등에 효과적으로 활용될 수 있을 것으로 판단된다.

• 한국도로학회논문집
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• 제19권1호
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• pp.73-80
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• 2017

PURPOSES : This paper presents a comparison study between dynamic and static analyses of falling weight deflectometer (FWD) testing, which is a test used for evaluating layered material stiffness. METHODS: In this study, a forward model, based on nonlinear subgrade models, was developed via finite element analysis using ABAQUS. The subgrade material coefficients from granular and fine-grained soils were used to represent strong and weak subgrade stiffnesses, respectively. Furthermore, the nonlinearity in the analysis of multi-load FWD deflection measured from intact PCC slab was investigated using the deflection data obtained in this study. This pavement has a 14-inch-thick PCC slab over fine-grained soil. RESULTS: From case studies related to the nonlinearity of FWD analysis measured from intact PCC slab, a nonlinear subgrade model-based comparison study between the static and dynamic analyses of nondestructive FWD tests was shown to be effectively performed; this was achieved by investigating the primary difference in pavement responses between the static and dynamic analyses as based on the nonlinearity of soil model as well as the multi-load FWD deflection. CONCLUSIONS : In conclusion, a comparison between dynamic and static FEM analyses was conducted, as based on the FEM analysis performed on various pavement structures, in order to investigate the significance of the differences in pavement responses between the static and dynamic analyses.

• 한국기계연구소 소보
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• 통권17호
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• pp.29-38
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• 1987

A mechanical linkage system to measure the operating temperature of the piston is developed and installed to the engine. Actual temperature distribution is measured for comparison with the numerical results. Heat transfer at the piston is analyzed using an FEM program. Thermal boundary condition of piston surface is determined by analytical and empirical methods. The temperature distribution and the thermal deformation are obtained by the FEM program.

• 국제초고층학회논문집
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• 제4권1호
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• pp.39-44
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• 2015

This paper presents the structural health monitoring (SHM) of Shanghai Tower. In order to provide useful information for safety evaluation and regular maintenance under construction and in-service condition, a comprehensive structural health monitoring (SHM) system is installed in Shanghai Tower, which is composed of a main monitoring station and eleven substations. Structural responses at different construction stages are measured using this SHM system and presented in this study. Meanwhile, a detailed finite element model (FEM) is created and comparison of results between SHM and FEM is carried out. Results indicate that the time-dependent property of concrete creep is of great importance to structural response and the measured data can be used in FEM updating to obtain more accurate FEM models at different construction stages. Therefore, installation of structural health monitoring system in super-tall buildings could be considered as an effective way to assure structural safety during the construction process.

• 한국생산제조학회지
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• 제8권4호
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• pp.106-111
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• 1999

This study discusses a non-contact optical technique electronic, electronic speckle pattern interferometry(ESPI) that is well suited for in-plane and out-of-plane deformation measurement Used as specimen which has the boundary condition of two clamped parallel edges composite material AS4/PEEK[30/-30/90]s was analyzed by ESPI to determined the characteristics of tensile and vibration. These are quantitativly compared with the result of FEM analysis. Finally the results of this study are briefly summarized as follows : (1) In the in-plane strain analysis by comparison of theoretical results with experimental results qualitatively we confirmed that measurement errors are within 3 % in case of accuracy (2) From comparison of experimental vibration modes with numerical vibration mode shapes by the FEM analysis quantitatively we confirmed that vibration mode measurement by the ESPI has high accuacy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1071-1072
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• 2011

The axial flux machine has higher power density than conventional radial flux machine, so it is widely applied to various industrial area, for instance, low speed wind power generator. For the conventional radial flux machine, 2D finite element method (FEM) is generally applied, but axial flux machine has to employ 3D FEM with long analysis time due to its own structural characteristic. This paper deals with the performance comparison of axial flux machine according to volume.

• Structural Engineering and Mechanics
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• 제47권3호
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• pp.345-359
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• 2013

For the purpose of investigating the free vibration response of the spatial curved beams, the governing equations are derived in matrix formats, considering the variable curvature and torsion. The theory includes all the effects of rotary inertia, shear and axial deformations. Frobenius' scheme and the dynamic stiffness method are then applied to solve these equations. A computer program is coded in Mathematica according to the proposed method. As a special case, the dynamic stiffness and further the natural frequencies of a cylindrical helical spring under fixed-fixed boundary condition are carried out. Comparison of the present results with the FEM results using body elements in I-DEAS shows good accuracy in computation and validity of the model. Further, the present model is used for reciprocal spiral rods with different boundary conditions, and the comparison with FEM results shows that only a limited number of terms in the resultant provide a relatively accurate solution.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 가을 학술발표회 논문집
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• pp.267-274
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• 1998

• 대한전기학회:학술대회논문집
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• 대한전기학회 1985년도 하계학술회의논문집
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• pp.13-16
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• 1985