• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.56-60
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• 1995

본 연구에서는 기존의 연구에서 다룬바 없는 분포하중의 경우에 대해 스펙트럴요소법을 적용하기 위해 1) 힘과 변위와의 관계를 이용하여 Bernoulli-Euler보와 1차원 Timoshenko-Mindlin평판에 대한 스펙트럴요소를 유도하고 2) 스펙트럴 요소법을 이용하여 분포하중을 받는 이들 구조물의 동적거동을 해석하고자 한다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.33-40
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• 2014

Reliability analysis of jacket type offshore wind turbine (OWT) support structure under extreme ocean environmental loads was performed. Limit state function (LSF) of OWF support structure is defined by using structural dynamic response at mud-line. Then, the dynamic response is expressed as the static response multiplied by dynamic response factor (DRF). Probabilistic distribution of DRF is found from response time history under design significant wave load. Band limited beta distribution is used for internal friction angle of ground soil. Wind load is obtained in the form of thrust force from commercial code called GH_Bladed and then, applied to tower hub as random load. In a numerical example, the response surface method (RSM) is used to express LSF of jacket type support structure for 5MW OWF. Reliability index is found using first order reliability method (FORM).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1773-1783
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• 1996

Finite element method(FEM) is one of the most popularly used method analyzing the dynamic behaviors of structures. But unless number of finite elements is large enough, the results from FEM some what different from exact analytical solutions, especially at high frequency range. On the other hand, as the spectral analysis method(SAM) deals directly with the governing equations of a structure, the results from this melthod cannot but be exact regardless of any frequency range. However, the SAM can be applied only to the case where a structure is subjected to the concentrated loads, despite a structure could be unddergone distributed loads more generally. In this paper, therefore, new spectral analysis algorithm is introduced through the spectral element method(SEM), so that it can be applied to anlystructures whether they are subjected to the concentrated loads or to the distributed loads. The results from this new SEM are compared with both the results from FEM and the exact analytical solutions. As expected, the results from new SEM algorithm are found to be almost identical to the exact analytical solutions while those from FEM are not agreed well with the exact analytical solutions as the mode number increases.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.89-96
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• 2001

In this study non-linear finite element analysis of dynamic response of steel arch under partially distributed dynamic load was discussed. Material and geometric non-linearities were included in finite element formulation and steel behavior was modeled with Von Mises yield criteria. Either radial or vertical dynamic load was dealt in numerical examples. Normal arch and arch with maximum shape imperfection of L/11,000 were studied. The analysis results showed that maximum displacement at the center of arch was occurred when 70% of arch span was loaded. The maximum displacement at a quarter of arch span was occurred when 50% of arch span was loaded and the displacement was larger than that of center of arch. Ratio of arch rise to arch span within 0.2∼-.3 seems to be appropriate for arch under radial or vertical load.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.61.1-61.1
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• 2011

풍력 터빈은 복잡한 바람 조건에 노출되어 운용 되는 시스템으로서 경제성과 신뢰성을 확보하기 위해서는 이러한 조건하에서 시스템에 작용하는 정확한 공력 하중 예측이 필요하다. 여러 조건 중에서도 요에러는 풍향이 수시로 바뀌기 때문에 피할 수 없는 비정상 유동 중에 하나이다. 본 연구에서는 이러한 요에러 발생시 공력 하중예측을 적절히 예측하기 위해서 와류 격자 기법을 기반으로 하는 비선형 와류 보정기법을 적용하였다. 비선형 와류 보정기법은 실속 이후의 공력 예측을 위해 기지의 공력 테이블을 이용하는 방법으로서 실속 이후의 공력 테이블 값의 양력과 와류 격자 기법에서의 양력 값이 일치하도록 순환(circulation)을 분포시키는 기법이다. 또한 요에러시에 발생할 수 있는 동적 실속을 계산하기 위해 Beddoes-Leishmen 동적 실속 모델을 비선형 와류 보정 기법에 적용하는 연구를 수행하였다. 요에러시 공력 하중 예측에 관한 수치해석 기법 연구의 적절성을 알아보기 위해 NREL-Phase VI Rotor 실험 결과와 비교 하였다. 그 결과 기존의 여타의 기법들과 비교하여 본 연구에서 제안한 기법의 적절성을 확인 할 수 있었다. 앞으로 본 연구를 바탕으로 다양한 비정상 공력 조건에 대한 풍력 블레이드의 공력 하중 해석에 대해 수행할 계획이다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.21-30
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• 1989

In this study, the dynamic behavior of a continuous bridge under moving load is studied considering roughness of the road surface. Vehicle model includes the spring effects of axes, and due to these effects, equations of motions for the vehicle and bridge are derived in coupled form. And then iteration method is used to solve the equations. In experimental study a bridge model is constructed considering the similarity rule in order that the model exhibits dynamic behavior similar to that of prototype. Three types of roughness such as uneven random roughness, uplift on the approach and piece-wise constant roughness are used to describe road roughness. Through the numerical analysis and experiments, the effects of surface roughness, sprung mass, and velocity on the dynamic behavior of the bridge are examined.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.821-829
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• 2006

Traffic load comprise primary input to pavement design causing pavement damage. therefore it should be proceeded suitable traffic load distribution modeling for pavement design and analysis. Traffic load have been represented by equivalent single axle loads (ESALs) which convert mixed traffic stream into one value for design purposes. But there are some limit to apply ESALs to other roads because it is empirical value developed as part of the original AASHO(American Association of State Highway Officials) road test. There have been many efforts to solve these problems. Several leading country have implemented M-E(Mechanistic-Empirical) design procedures based on mechanical concept. As a result, they established traffic load quantification method using load distribution model known as Axle Load Spectra. This paper details Axle Load Spectra and presents axle load distribution model based on normal mixture distribution function using truck load data collected by WIM system installed in national highway. Axle load spectra and axle load distribution model presented in this paper could be useful for basic data when making traffic load quantification plan for pavement design, overweight vehicle permit plan and pavement maintenance cost plan.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.134-138
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• 2011

Fault detection for dynamic loading conditions of rotational machineries was considered from the contactless, non-destructive infrared thermographic method, rather than the traditional diagnosis method. In this paper, by applying a rotating deep-grooved ball bearing, passive thermographic experiment was performed as an alternative way proceeding the traditional fault monitoring. In addition, the thermographic experiments were compared with the vibration spectrum analysis to evaluate the efficiency of the proposed method. Based on the results, it was concluded the temperature characteristics of the ball bearing under dynamic loading conditions were analyzed thoroughly.

• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.25-27
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• 1994

선박의 고속화, 경량화, 전문화 및 대형화의 촉진과 더불어 신형식 선박의 출현으로 기존의 해 석방법과 같은 개념으로는 새로운 문제점에 대한 해결이 불가능하다. 따라서 이와 같은 새로운 외력환경에 대한 신형식 선박에 구애받지 않고 범용으로 이용이 가능할 수 있게 하기 위해서는 하중의 공간적 분포와 시간적 변화에 대한 정보를 정도 높게 추정할 수 있는 방법이 바람직하 다고 본다. 이를 해결할 수 있는 유일한 방법은 우리가 지금까지 소흘하여 왔던 반복적 실험이 뒷받침되어, 수치이론의 모델화 과정에서나 물리현상 설정과정에서 내재하게 되는random한 불확실성을 정량적으로 파악해 두어야 신형식 선박 개발에 신뢰할 수 있는 동적 응답해석이 가 능해질 것이다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.175-184
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• 2006

Two methods of the nonlinear static pushover analysis have been presented for the performance-based seismic design and evaluation of MDOF continuous bridges. Guidelines for buildings presented in FEMA-273 applying the Displacement Coefficient Method (DCM) and in ATC applying the Capacity Spectrum Method(CSM) have been modified for MDOF bridges. Two methods are compared with the time- history analysis. The lateral load distribution pattern for seismic loads has been examined in the static pushover analysis. The force-based fiber frame finite element has been implemented in the modeling of reinforced concrete piers.