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유도초음파의 시간-역전 현상을 활용한 구조손상 진단기법
이우식(Usik Lee),최정식(Jungsik Choi) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.6
This paper proposes a new TR-based baseline-free SHM technique in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM technique has two distinct features when compared with the other TR-based SHM techniques: (1) The backward TR process commonly conducted by the measurement is replaced by the computation-based process; (2) In place of the comparison method, the TOF information of the damage signal extracted from the reconstructed signal is used for the damage diagnosis in conjunction with the imaging method which enables us to represent the damage as an image. The proposed TRbased SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.
이우식(Lee Usik),박철희(Pak Chol-Hui) 한국철도학회 1999 철도저널 Vol.2 No.3
A high speed train named Korean High Speed Train (KHST) with its maximum operating speed 350 km/h is now under development. For the successful design of a quiet and comfortable high speed train, it is important to understand the general features of the noise and vibration characteristics of high speed train. This paper reviews extensively collected materials on the noise and vibration characteristics of existing high speed trains. Based on the noise and vibration characteristics of TGV systems, a simple indoor-noise prediction rule is proposed for the TGV-type high speed trains such as KHST. The indoor-noise of KHST at 350km/h is expected to be larger than at least 71 dBA. Some important researches conducted for designing KHST during last two years under the G-7 project are also briefly introduced at the last part of this paper.
Introduction to Spectral Element Method in Structural Dynamics
이우식(Lee Usik),장인준(Jang Injoon) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월
The purpose of this paper is to provide a brief introduction to the spectral element method in structural dynamics for the engineers in the areas of mechanical engineering, civil engineering, aerospace engineering, computational mechanics, and so forth. The contents cover the associated historical and theoretical background, theories, advantages, and the example applications in the real world, though not all of them are not included in the present manuscript. As an illustrative example, the spectral element method is applied to an axially moving Timoshenko beam.
고속전철 진동소음해석 및 저감기술개발 : G-7과제개요 및 연구방향
이우식(Lee Usik),박철희(Pak Chul-Hui) 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper introduces the outline of the ongoing G-7 project for the development of vibration and noise analysis and reduction technology for the Korea High Speed Train which will run at 350㎞/h. Extensively collected materials and data on the vibration and noise characteristics of high speed trains are summarized herein to reduce the research direction.
구조물 건전성 모니터링을 위한 하이브리드 시간-반전기법
이우식(Usik Lee),김대환(Daehwan Kim),전용주(Yongju Jun) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7
This paper proposes a new baseline-free TR-based SHM method in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM method has two distinct features when compared with the other existing SHM techniques: (1) The measurement- based backward TR process is replaced by the computation-based process (2) In place of the comparison method most commonly used for SHM, the TOF information of the damage signal extracted from the reconstructed signal is utilized for the damage diagnosis. For the damage diagnosis, the imaging method is adopted to efficiently detect damage by representing the damage as an image. The proposed TR-based SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.
변분법을 이용한 확장된 티모센코 보에 대한 스펙트럴 요소 모델링
이창호(Lee Changho),이우식(Usik Lee) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
Periodic lattice structures such as the large space lattice structures and carbon nanotubes may take the extension-transverse shear-bending coupled vibrations, which can be well represented by the extended Timoshenko beam theory. In this paper, the spectrally formulated finite element model (simply, spectral element model) has been developed for extended Timoshenko beams and applied to some typical periodic lattice structures such as the armchair carbon nanotube, the periodic plane truss, and the periodic space lattice beam.