• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.377-385
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• 1996

In the case of a precision equipment, it requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga class semiconductor wafers. This high technology equipments require very strict environmental vibration standard in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria are usually obtained either by the real vibration exciting test on the equipment or by the analytical calculation. the former is accurate but requires a great deal of time and efforts while the latter lacks reliability. this paper proposes a new method to solve this problem at a time. the permissible vibration level to a precision equipment can be easily obtained by analyzing a process of Frequency Response Function. This paper also demonstrates its effectiveness by applying the proposed method to finding the vibration criteria of a Computer Hard Disk Drive by impact Test.

• Structural Engineering and Mechanics
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• v.85 no.4
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• pp.445-459
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• 2023

The current investigation is the first endeavor to apply the full layerwise finite element method (FEM) in free vibration analysis of functionally graded (FG) composite plates reinforced with graphene nanoplatelets (GPLs) in thermal environment. Unlike the equivalent single-layer (ESL) theories, the layerwise FEM focuses on all three-dimensional (3D) effects. The GPLs weight fraction is presumed invariable in each layer but varies through the plate thickness in a layerwise model. The modified Halpin-Tsai model is employed to acquire the effective Young's modulus. The rule of mixtures is applied to specify the effective Poisson's ratio and mass density. First, the current method is validated by comparing the numerical results with those stated in the available works. Next, a thorough numerical study is performed to examine the influence of various factors involving the pattern of distribution, weight fraction, geometry, and size of GPLs, together with the thickness-to-span ratio, thermal environment, and boundary conditions of the plate, on its free vibration behaviors. Numerical results demonstrate that employing a small percentage of GPL as reinforcement considerably grows the natural frequencies of the pure epoxy. Also, distributing more square-shaped GPLs, involving a smaller amount of graphene layers, and vicinity to the upper and lower surfaces make it the most efficient method to enhance the free vibration behaviors of the plate.

• Journal of KSNVE
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• v.7 no.3
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• pp.369-376
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• 1997

With recent progress of developing infrastructure, construction vibration from the sites and traffic vibration caused by high-speed rail, subway, and roads is becoming a hazardous factor for vibration environment. In order to predict the damages caused by the vibrations mentioned above the vibration sources, have to be distinguished between point vibration and line vibration. Once the character of the vibration source is determined vibration propagation phenomenon needs to be analyzed by using prediction formula, and compared to the limits authorized by the law. The main purpose of this thesis is to manage the efficient vibration by reflecting these finding in making a consrtuction plan. Therefore, Vibration Management System (VMS) was developed which can predict and analyze the extent of developed utilizing Geographic Information System (GIS) to build a database. This database contains the attribute and the location information of the sources for predicting the formula of explosive vibration and subway traffic vibration, the buildings, the surrounding area and measurement sites. VMS will be useful in the future for predicting the vibrations caused by pile drive, traffic vibrations such as high speed electric railway, highway and roads, and other explosive vibrations by supplementing and updating the database.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.289-290
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.97-97
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• 2000

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1075-1075
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• 2006

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.380-381
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• 2012

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.510-515
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• 2005

Subway lines often pass through the densely populated districts. As the social interest about environment is more and more increased, the need of countermeasure to the vibration generated by subway train is grossing nowadays. It will be effective to take a measure in the track part, specially at the track design stage. In this study, the vibration proof performances for the various types of the tracks adopted in domestic and foreign countries are evaluated. Based on the results, the criteria of vibration proof performance to meet the demands of the both of populated and normal areas are established.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.7
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• pp.575-582
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• 2018

The spaceborne cooler is applied to cool down of the focal plane of the infrared detector of the observation satellite. However, this cooler induces unnecessary micro-jitter which can degrade the image quality of the high-resolution observation satellite. In this study, we proposed a multi-layered blade type vibration isolator to attenuate micro-vibration generated from a spaceborne cooler, while assuring structural safety of the cooler under severe launch loads without an additional launch-lock device. The blade of the isolator is formed with multi-layers in order to obtain durability against fatigue failure and an adhesive is applied between each layers for granting high damping capability under launch vibration environment. In this study, the basic characteristics of the isolator were measured using the free-vibration test. The effectiveness of the isolator design was demonstrated by launch vibration test at qualification level.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.897-904
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• 2017

Optical equipment consists of various components, and a detector is mounted and operated on aircraft, tanks, and warships for target detection and classification. The structural stability and optical performance of aeronautical optical equipment operated at several kilometers of altitude are degraded owing to vibration generated in the aircraft. It is necessary to verify the structural stability and optical performance requirements of the equipment in vibration environment conditions during the design phase. In this study, vibration environment conditions were analyzed using a test standard and the measurements of the vibration generated in aircraft. The conditions were classified as endurance and operating vibration conditions for structural stability and optical performance verification, respectively. The structural stability was verified according to natural frequency analysis, response analysis for the endurance vibration condition, and static analysis. The optical performance was verified by applying the vibration response analysis results to the optical design/analysis program.