• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.89-96
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• 2015

To reduce noise inside an elevated railroad station, the vibration of the station structure should be lowered, and to establish more effective anti-vibration measures it is required that, reflecting the track-bridge-structure interaction, the transfer characteristics of vibration induced by a train is well identified. In this paper, the current status of domestic railroad stations is classified, and the vibration transfer characteristics is analyzed via measurement data from representative elevated stations. From the analysis results on the measurement data, in transferring vibration from the track to the structure, remarkable vibration reduction in higher frequency range is observed, and, in some stations, amplified response characteristics in lower frequency range is identified. Also, for stations with floating track system or TPS type, relatively greater reduction in transferred vibration is observed.

• Transactions of Materials Processing
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• v.14 no.1 s.73
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• pp.37-42
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• 2005

In order to invstigate the influence of die design variables on the quality of the sheared surface in cutting of sandwich sheet metals, the cut-off operation is carried out, which is the typical shearing process in sheet metal forming technology. For experiments we made the cut-off die which can be easily adjusted for die design variables such as blankholding force, pad force and clearance. The sandwich sheet metals considered are clad304(STS304-Al1050-STS304) and anti-vibration sheet metal. The shearing process is visualized by the computer vision system installed in front of the cut-off die and the sheared surface is measured and quantitatively compared with the help of the optical microscope after cut-off operation. From test results it is shown that the shearing mechanisms are different according the material of which sandwitch sheet metal is composed. The influence of die design variable is explored and we found optimal conditions for both sandwich sheet metals. It is expected that this investigation can be utilized to get the better sheared surface.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.57-61
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• 2004

in order to improve the quality of the sheared surface in cutting of sandwich sheet metals the cut-off operation is mainly investigated which is the typical shearing process in sheet metal forming technology. For experiments the cut-off die is made which can be easily adjusted by die design variables such as blankholding force, pad force, and clearance. The sheet metals chose as specimen are clad304(STS304-Al1050-STS304) and anti-vibration sheet metal. The shearing process is visualized by the computer vision system installed in front of the cut-off die and the sheared surface before and after cut-off operation is measured and quantitatively compared with the help of the optical microscope. From test results the good sheared surface was shown when the clearance gets small with large blankholding force.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.4
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• pp.211-216
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• 2014

In general, gantry robot is very useful handling of heavy objects. But rope-driven yard cranes must have a little of sway and skew motion because ropes are passive mechanical device. So many researches have been concentrated on anti-sway algorithm controlling trolley speed. These approaches require sway angle. But it is very difficult to know sway angle and its derivative. Therefore control algorithm of trolley speed is not practical in general. On the contrary, control strategy using auxiliary rope is very useful to sway control of yard crane because rope length is shorter than quay-side container cranes. In this paper, we derive equations of motion of trolley system which have anti-sway controller to use auxiliary rope. And we propose the control strategy and analyse the behavior of the proposed system.

• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.32-35
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• 2013

Nowadays, function related to anti-vibration and anti-shock of storage devices is required because of portability. Therefore, many hard disk drive (HDD) studies about external shock and vibration have been performed. Especially, many studies are performed with non-operational shock. Most studies have used the fixed condition between spindle system and base when they wanted to analyze dynamic behavior of inner parts in simulation. But spindle system has actually stiffness and damping coefficient. Maybe difference of value would be happened between fixed condition and spring condition. So, we measured FRF of spindle system to know stiffness and damping coefficient in HDD. And we studied on dynamic behavior of inner parts by using calculated stiffness and damping coefficient. As a result, we confirmed the difference as boundary condition of spindle system.

• Special Issue of the Society of Naval Architects of Korea
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• 2006.09a
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• pp.106-111
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• 2006

The steel outfitting structures installed in engine room are vibrated by an excitation of the engine and the propeller. Vibration problems such as cracks and fitting breakages are mainly induced at the near range of the resonance. The excitation frequency estimation is possible by engines and propeller specifications, but the natural frequency of a steel outfitting structure is not easily estimated due to the complication and variety of the designed shape. This paper represents natural frequency data of simple steel outfitting structures. As a vibration analysis tool, MSC/NASTRAN was used to calculate natural frequencies. Natural frequencies were compared in case of the shape and boundary condition changes of simple models, and anti-vibration models of the steel outfitting structures were presented on the basis of results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.75-78
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• 2014

MLCC is one of the most frequently used component in high-tech device like smart phone. Because of dynamic characteristic of piezoelectric materials which is main ingredient of MLCC, its vibration leads to acoustic noise from pcb. To solve this problem at minimal cost, company has to change only the main noise-generating MLCC to low noise-generating MLCC. To find the main noise source, this study approached to solution from a vibration point of view. From mode shapes of pcb at particular frequencies, two groups can be obtained; MLCCs soldered at where maximum deformation occurs and where anti-phase with respect to the other group appears. When the MLCC belongs to 1st group does not working, amplitude at where maximum deformation occurs decreases compared to when all MLCCs are working. This tendency also appears in noise measurement. This analysis can be put to use in various fields where require noise reduction or noise source identification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.483-488
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• 2013

The psychoacoustic quality of ABS is now considered more important than before as the focus of recent ABS function is expanded to basic function from typical emergency function. Thus, the automotive parts manufacturing companies are actively working to improve NVH (Noise, Vibration, and Harshness) in ABS module. In terms of time, test place, and cost, however, it is very inefficient to have all the operating noise validation test in real vehicle configuration especially for partially improved ABS module. To contribute to reducing the development period and to grasping the improvements faster, this research presents the study of a correlation to predict ABS operating noise inside vehicle via HILS rig test. The regression equation in this paper was statistically drawn from using Minitab S/W, and based on that equation, the noise spectrum of vehicle interior was analogized.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.487-492
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• 2005

The structural intensity analysis, which calculates vibration energy flow from vibratory velocity and internal force of a structure, can give information on sources' power, dominant transmission path and sink of vibration energy. In this study, we present a system for structural intensity analysis and visualization to apply for anti-vibration design of ship structures. The system calculates structural intensity from the results of forced vibration analysis and visualize the intensity using a general purpose finite element analysis program MSC/Nastran and its pre- and post-processor program. To demonstrate the analysis and visualization capability of the presented system, we show and discuss the results of structural intensity analysis for a cross-stiffened plate and a 70,500 OW crude oil tanker

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.50-59
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• 2005

This paper described performance test of 1st prototype "Tail-Fan" system. KARI(Korea Aerospace Research Institute) developed "Tail-Fan" system as a kind of helicopter anti-torque system(ATS) and designed ATS performance test-rig for Tail-Fan system performance test. For Tail-Fan system performance tests, firstly, test-rig operation tests were carried out for verification of design specifications. And natural frequencies of fan blade and test-rig were measured respectively. To find the operation rotating speed for performance tests, vibration tests using accelerometers on tail gear box(TGB) were carried out. Through the fanplot and vibration test results, rotational speed for Tail-Fan performance test to avoid a resonance were found and performance tests were carried out in flight conditions. We analyzed test data by non-dimensionalization. Through this results, 1st prototype "Tail-Fan" system was satisfied with design requirements.