• 한국해양공학회지
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• 제24권1호
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• pp.90-98
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• 2010

In this paper, vibration-based structural health monitoring methods that are suitable for caisson-type structures are examined by an experimental evaluation. To achieve the objective, four approaches are implemented. First, vibration-based structural health monitoring methods are selected to monitor the structural condition of caisson-type breakwaters. Second, a lab-scaled caisson structure is constructed to verify the selected monitoring methods. Third, the vibration characteristics are numerically analyzed using an FE model due to the change in the rubble mound condition. Finally, experimental vibration tests of the lab-scaled caisson structure are performed to monitor the vibration responses due to changes in rubble mound conditions and the performances of the selected methods are examined from the monitoring results.

• 항공우주시스템공학회지
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• 제3권2호
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• pp.20-23
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• 2009

The structural analysis of liquid rocket engine was performed in the case of sinusoidal vibration load to verify structural safety. The finite element model is composed with main liquid rocket engine components, combustion chamber, turbopump, gas-generator, pyro-starter, main pipes, main valve, heat-exchanger, gimbal-mount and brackets. Natural vibration mode analysis and structural analysis for sinusoidal vibration load were performed. The natural mode frequency of liquid rocket engine is twice than that of launch vehicle. In the case of stress result of sinusoidal vibration load, the part of maximum stress has 1.4 margin, so the engine structure is safe for sinusoidal vibration load.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.300-305
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• 2012

The vibration and stress analysis program of comprehensive vibration assessment program (CVAP) is to verify theoretically the structural integrity of reactor vessel internals (RVI) and to provide the basis for selecting the locations monitored in measurement and inspection programs. This paper covers the verification of the vibration and stress analysis methodology of APR1400 RVI CVAP. The analysis methodology was developed to use 3-dimensional hydraulic and structural models with ANSYS and CFX. To validate the methodology, the hydraulic loads and structural reponses of OPR1000 were predicted and compared with the calculated and measured data in the OPR1000 RVI CVAP. Since the results predicted with this methodology were close to the measured values considerably, it was confirmed that the analysis methodology was developed properly.

• The Journal of the Acoustical Society of Korea
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• 제19권3E호
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• pp.3-11
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• 2000

A structural modification technique for reducing structure-borne noise of vehicles using a sensitivity analysis is suggested. To estimate the noises generated by the vibration response, a semi structure-acoustic coupling analysis was exploited. As a result of the coupling analysis, severe noise generating positions are identified whose vibrations should be cured through structural modifications. Formulation for the sensitivity analysis of those severe vibration responses with respect to the design changes is derived to enhance the vibration response. Special attention is given in this paper to the use of the experimentally measured vibration responses in the sensitivity analysis. As a result of the proposed method, the structural modifications can be peformed accurately by using experimental data instead of using the finite element method though the higher vibration modes are considered as long as the vibration measurement and acoustic mode calculations are accurate. Effectiveness of this method was examined using an example model by experiments.

• 한국소음진동공학회논문집
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• 제19권5호
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• pp.491-498
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• 2009

This paper deals with structural analysis and vibration characteristics of scaffolding structures with a hoist according to payloads. In order to analyze the vibrational and structural characteristics for 20-step scaffolding structure, structural and vibrational characteristics for 2-step scaffolding structure were compared with some experimental results. The numerical results for natural frequencies of scaffolding structures have a good agreement with experimental ones. Through the numerical analysis, firstly, it is shown that the maximum stress of scaffolding structures is lower than von-mises yield criteria when four persons with total weight of 280 kgf are working at the top of the scaffolding structures. Secondly, vibration characteristics including natural frequencies and modes for scaffolding structures are shown in case of various kinds of moving masses.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.215-217
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• 2008

This paper deals with the structural vibration characteristics for an outdoor units support of an air-conditioner. Even though main noise sources are compressor noise and fluid noise which is caused by the fan, the structural modification of the outdoor units support may affect vibration and noise. In this paper, damping ratios for two kinds of an outdoor units support of an air-conditioner are measured through the modal testing. In order to reduce the structural borne noise due to an outdoor units support of an air-conditioner, four kinds of rubber materials are selected and tested.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.201-207
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• 1995

A series of vibration assessment programs has been performed for Yonggwang Nuclear Power Plant Unit 4 (YGN 4) in order to verify the structural integrity of the reactor internals for flow induced vibration prior to its commercial operation. The structural analysis was done to provide the basis for measurement and the theoretical evidence for the structural integrity of the reactor internals. The actual flow induced hydraulic loads and reactor internals vibration response data were measured and recorded during pre-core hot functional testing of the plant. Then, the measured data have been reduced and analyzed, and compared with the analysis results such as the frequency contents, stresses, strains and displacements. It is concluded that the structural analysis methodology performed for vibration response of the reactor internals due to the flow induced vibration is appropriately conservative, and also that the structural integrity of YGN 4 reactor internals to flow induced vibration is acceptable for long term operation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.273-276
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• 2014

The development of a vehicle-mounted radar to detect the location of enemy artillery is mainly mounted during operation to the mobility of the equipment and efficiency of utilization range. It is equipped with an electronic device responsible for the operation of the radar system. Electronic equipments is performed functionality imparted without an error-specific in spite of disturbances such as vibration / shock caused by vehicle movement. Therefore, vibration / shock resistance is held to prevent damaging from vibration / shock generated from the outside environment during operation. In addition, a standardized and specified cabinet structure equipped with electronic equipment is placed in shelter to ensure additional safety for vibration / shock. In this study, it is evaluated by analytical method with vibration / shock resistance of the cabinet structures for ensuring structural safety factor is applied to the aluminum. It is verified the reliability of the structure and structural dynamics to verify by calculated natural frequencies adding the weight of the cabinet structure and the structural displacement and stress results confirmed with vibration / shock caused by the vehicle movement.

• Smart Structures and Systems
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• 제15권2호
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• pp.259-281
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• 2015

In this study, a structural identification method is proposed to assess the integrity of gravity-type caisson structures by analyzing vibration features. To achieve the objective, the following approaches are implemented. Firstly, a simplified structural model with a few degrees-of-freedom (DOFs) is formulated to represent the gravity-type caisson structure that corresponds to the sensors' DOFs. Secondly, a structural identification algorithm based on the use of vibration characteristics of the limited DOFs is formulated to fine-tune stiffness and damping parameters of the structural model. Finally, experimental evaluation is performed on a lab-scaled gravity-type caisson structure in a 2-D wave flume. For three structural states including an undamaged reference, a water-level change case, and a foundation-damage case, their corresponding structural integrities are assessed by identifying structural parameters of the three states by fine-tuning frequency response functions, natural frequencies and damping factors.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.199-204
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• 1993

Noise and vibration induced by subway operation are one of the major factor that annoying residents living near the. railway. In general, lateral vibration was the major concern when we are considering vibration of the building. Since the energy due to earthquake is enormous it affects wide area. However, the vertical vibration became a major concern in considering the vibration induced by subway because relatively smaller energy affects only nearby areas than that of earthquake. Analysis model of the structure for the vertical vibration should consider the effect of beam vibration. Thus, the model of the structure for the lateral vibration can not be applied. Appropriate analysis model which can consider the inertia force of the beam is necessary when analyzing a structure for the vertical vibration. Modeling technique for the vertical vibration analysis of structures has been studied on this paper. It is recommeneded to use 2 or more elements for columns and to use 3 or more elements for beams when analyzing structures for vertical vibration induced by subway.