• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.513-519
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• 2016

In this study, dynamic vertical displacement of liquid in the tuned liquid column damper(TLCD) is measured by a laser Doppler vibrometer(LDV) to overcome limitations of existing sensors and to leverage noncontact sensing. Addressing advantages of noncontact measurements, operational principles of the LDV to measure velocity and displacement of a target object in motion is explained. The feasibility of application of the LDV to measurement of liquid motion in the TLCD is experimentally explored. A series of shake table tests with the TLCD are performed to determine requirements of application of the LDV. Based on the experimental results, it is proved that the LDV works under the condition of adding dye to the liquid by increasing the intensity of reflected laser and thus validity is verified by comparison with a conventional wave height meter.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.214-219
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• 2012

초음파전파영상화(UPI) 시스템은 2007년에 첫 논문 발표를 통해 시스템 개발이 보고된 이후 소프트웨어 및 하드웨어적 측면에서 다양한 형태로 발전된 시스템의 개발이 이루어졌다. 본 기고에서는 기본 UPI 시스템, 섬유파트랜스듀서 UPI 시스템, 순수광학시스템으로서 광섬유 센서 UPI 시스템, 완전비접촉 시스템으로서의 공기정압압전센서 UPI 시스템 및 레이저도플러진동계 UPI 시스템, 장거리 UPI 시스템, 옥외 적용성에 필수적인 저온환경 UPI 시스템 등을 소개한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.227-234
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• 2018

Researches regarding measurement and control of the dynamic behavior of liquid such as sloshing have been actively on undertaken in various engineering fields. Liquid vibration is being measured in the study of tuned liquid dampers(TLDs), which attenuates wind motion of buildings even in building structures. To overcome the limitations of existing wave height measurement sensors, a method of measuring liquid vibration in a TLD using a laser Doppler vibrometer(LDV) and galvanometer scanner is proposed in this paper: the principle of measuring speed and displacement is discussed; a system of multi-point measurement with a single point of LDV according to the operating principles of the galvanometer scanner is established. 4-point liquid vibration on the TLD is measured, and the time domain data of each point is compared with the conventional video sensing data. It was confirmed that the waveform is transformed into the traveling wave and the standing wave. In addition, the data with measurement delay are cross-correlated to perform singular value decomposition. The natural frequencies and mode shapes are compared using theoretical and video sensing results.