• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.294-303
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• 2021

Various types of sensors are used at industrial sites to measure vibration. With the increase in the diversity of vibration measurement methods, vibration monitoring methods using camera equipment have recently been introduced. However, owing to the physical limitations of the hardware, the measurement resolution is lower than that of conventional sensors, and real-time processing is difficult because of extensive image processing. As a result, most such methods in practice only monitor status trends. To address these disadvantages, a high-resolution vibration measurement method using image analysis of the edge region of the structure has been reported. While this method exhibits higher resolution than the existing vibration measurement technique using a camera, it requires significant amount of computation. In this study, a method is proposed for rapidly processing considerable amount of image data acquired from vision equipment, and measuring the vibration of structures with high resolution. The method is then verified through experiments. It was shown that the proposed method can fast measure vibrations of structures remotely.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.148-156
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• 2016

The paper deals with improvement of a piezoelectric ultrasonic transducer for measuring both pipe thickness and flow velocity. The transducer structure is based on the conventional transducers for measuring flow velocity by obliquely transmitting ultrasonic waves to the flow direction. The transducer invented earlier for measuring flow velocity and pipe thickness had an advantage of including only one piezoelectric disc, but for the thickness measurement the ultrasonic wave had to be reflected twice in a wedge material to be transmitted vertically to a pipe, and thus the wave signal was too weak. The transducer has been improved to transmit waves for thickness measurement vertically to a pipe without any prior reflection by electrically connecting two piezoelectric discs, one for flow velocity and the other for pipe thickness measurement. By comparing the measured results of specimen thickness with the improved transducer and conventional transducers, the accuracies of the improved one have been evaluated in the pipe thickness measurements.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1089-1098
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• 2012

A faulting could be occurred at the end of deck by unexpected loads to bridge bearing after a bridge completion. Serviceability of bridges could be impaired by the faulting which is caused structural damage. Therefore, smart bridge bearing which can continuously observe the supporting points is needed. Some of bridge bearings have been developed for measuring vertical load and vertical displacement by installing sensors in the bearing. In those systems, however it is not easy to be replaced with new sensors when repairs are needed. In this study, the smart bridge bearing of which sensors can be replaced has been developed to overcome such a problem. In this study, strain signals were used for measuring both of vertical displacements and loads. FBG sensors(fiber optic Bragg-grating sensors) have been used for measurement of the strain signals since it is prevented from electronic noise by mediating light, enables the simplification of the measuring cable by multiple measurement, and is easy to place by lightweight and small size. The possibility of use was reviewed for smart bridge bearing based on FBG sensors through tests.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.519-522
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• 2008

As industry of a semiconductor and LCD industry have been rapidly growing, precision technologies of machining such as etching and 3D measurement are required. Stylus has been important measuring method in traditional manufacturing process. However, its disadvantages are low measuring speed and damage possibility at contacting point. To overcome mentioned disadvantage, non-contacting measurement method is needed such as PMP(Phase Measuring Profilometry), WSI(white scanning interferometer) and Confocal Profilometry. Among above 3 well-known methods, WSI started to be applied to FPD(flat panel display) manufacturing process. Even though it overcomes 21t ambiguity of PMP method and can measure objects which has specular surface, the measuring speed and vibration coming from manufacturing machine are one of main issue to apply full automatic total inspection. In this study, We develop high speed WSI system and algorithm to reduce unknown noise. The developing WSI and algorithm are implemented to measure 3D surface of wafer. Experimental results revealed that the proposed system and algorithm are able to measure 3D surface profile of wafer with a good precision and high speed.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1305-1310
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• 2014

In this paper, the new integrated crane monitoring system that complemented the point at issue for existing crane monitoring system is implemented. The Implementing monitoring system based on wireless communication system, consist of a measuring system of total load currents of main circuit breaker, a temperature and vibration measuring system with temperature sensors and vibration sensors for monitoring an oil and bearing of a main decelerator, a temperature measuring system with temperature sensors of a main motor bearing, and sensors for fire monitoring of an entire electrical space. The measured data from these sensors transmit main controller which is located in external location. Then the Integrating monitoring system is implemented and is performed the performance test to performing diagnosis of motors of a crane.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.1
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• pp.47-54
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• 1997

Flake graphite cast irons with the high damping capacity have been used for the control of vibration and noise occuring in the members of various mechanical structures under vibrating conditions. However, the damping capacity which is morphological characteristics of graphite is one of the important factors in reducing the vibration and noise, but hardly any work has deal with this problem. Therefore, the authors have examined the damping capacity of various cast irons with alloying elements and studied the influences of the matrix, mechanical properties and morphological characteristics of graphite. The main results obtained are as follows: Effects of Ni on the damping capacities and mechanical properties are investigated in 3.9%C-0.3% Cu gray cast iron. At 0.2% Ni content, specific damping capacity showed the maximum value, and decreased with further increase in Ni content, Graphite continuity also showed same behavior. This indicates that the specific damping capacity has a close relation with graphite continuity. On the other hand, the damping capacity in pearlite matrix showed superior to that in ferrite. In contrast, with increasing the Ni content, both tensile strength and hardness increased due to the decrease of graphite length and eutectic cell size.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.4
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• pp.40-46
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• 2003

In this research, we accomplished the interpreting about the vibration of the object, which is the out of plane displacement in the Electronic Speckle Pattern Interferometry(ESPI), one of the optical measuring technique. The vibrating object has a inherent nodal line, therefore we can get the information about the vibration of the object by interpreting it. we used a speaker and a cantilever plate for a measurement object, and interpreted it qualitatively by using the Time-Average ESPI. In this experimental result, the speaker has the lower mode of fringe at 550Hz, 570mV, and the higher mode of fringe at 950Hz, 570mV This ESPI is a non-destructive test, and because of using the laser at measuring, it has a high resolution. The ESPI can test vibration mode regardless of the test object size, because the area which illuminated laser is the test area.

• Tunnel and Underground Space
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• v.2 no.2
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• pp.199-211
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• 1992

Blasting vibrations of 3 quarries and 5 construction sites were measured and investigated with two reference data. Square and cubic root scaled distance were similar in fitness to peak particle velocity of individual blasting site, but the former is better fitted in total. It was suggested that the limit scaled distance for domestic surface blasting be 40kg/$\textrm{cm}^2$ for 10mm/s level and 60kg/$\textrm{cm}^2$ for 5mm/s level, which were lower than the OSM's regulation. Prevailing vibration components were in the order of radial, vertical and transverse directions. Prevailing vibration components were in the order of radial, vertical and transverse directons. Site factors K and m were 242 and -1.283 for all studied area, 357 and -1.348 for construction sites, 118 and -1.160 for quarries. Most prevailing frequency was in the range of 10~2Hz. Overlapping effect of delayed blasting vibrations were insignificant. Vibration history of delayed blasting was longer than simultaneous blasting, and it became longer as measuring distance increased. Wave form and predominant frequencies were more complicated for delayed blasting than instantaneous blasting. The influence of blasting scale and measuring distance were not significant to determine peak particle velocity equation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.12
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• pp.1082-1089
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• 2013

3-Axis sensor measurement system is needed for measuring ride quality of elevator. But because 3-Axis piezoelectric accelerometer is expensive. We developed 3-Axis sensor system which is suitable for measuring ride quality of elevator using cheap MEMS sensor. There are two types of MEMS sensor that are piezoresistive and capacitive type. The excellence of piezoresistive type in characteristic of frequency response and noise is confirmed compare to capacitive type as a result of this paper's experiment and reference. 3-Axis system using MEMS sensor needs MEMS's proper frequency response characteristic. Additionally noise characteristic of sensor and circuit, stiffness of assembly are needed for deciding frequency range and accuracy of amplitude.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.781-786
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• 2009

The thesis shows that we gauged vibration of vehicular load regarding WPC girder bridge and researched into dynamic characteristics(natural frequency, vibration acceleration) of WPC girder bridge. By the basic of that, we researched on vibration serviceability by looking over and being compared to vibration criteria we had before. In the thesis, the gauged vibration made an analysis of vertical acceleration through FFT method and evaluated vibration serviceability about vibration sense the body feels by means of the standard of ISO assessment standard and Meister assessment standard by referring to analysis data. This research on bridge is WPC girder bridge of 90m span, width of 5.5m, and the experiment was gauged by a fluent which is right way and inverse way about dump truck of gross 270kN. Acceleration was located in the middle of 1st span, 2nd span, 3rd span. As a result of appraisal standard of Meister, the vibrations of the bridge have distributed between "Level C, Strongly Perceptible" and "Level B, Disturbing". Also the vibration can be attacked with unpleasant feeling. As a result of appraisal standard of ISO, from vibration influence didn't come to 60s, and reduced comfort boundary in part of most rigorous standard that such a case didn't happen.