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CFRP로 보강된 RC보의 AE 신호특성 및 이를 활용한 정량적 손상 평가
이영오(Lee Young-Oh),윤현도(Yun Hyun-Do),서수현(Seo Soo-Yeon) 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.11
CFRP(Carbon Fiber Reinforced Polymer) has been widely used for reinforcement and rehabilitation of damaged concrete structure, and that offer many advantages when compared to conventional steel. Reinforced concrete structure reinforced with CFRP is difficult to estimate for damage, but characterization of acoustic emission (AE) can be demonstrated the micro damage that was not discovered from visual observation and it become known to an advantage that was discriminated from the existing nondestructive technique method. This study was investigated the evolution of fracture damage of reinforced concrete (RC) beams strengthened in flexure with CFRP sheets using AE technique, and developed an AE monitoring strategy that can determine the structural integrity of RC beams strengthened by external bonding of CFRP sheets. In order to analysis the acoustic emission signal of concrete beams reinforced with CFRP, a total of 4 specimens were tested under four point bending. CFRP is reinforced a bottom, side 40% and side 100% of specimen. And AE sensor is attached a side of specimen by triangle method. The aim of this study was to examine the emission of acoustic signals from four CFRP reinforced concrete beams at cracking, failure processes and the failure mechanism of specimens. The AE signal of the RC beams strengthened with CFRP was evaluated using the AE parameters, such as AE counts, amplitude, hits, duration time, amplitude/rise time and b-value. The two-dimensional AE source location was successful in measuring crack initiation and propagation in the RC beams strengthened with CFRP.
이영오(Lee Young-Oh),전수만(Jeon Soo-Man),김선우(Kim Sun-Woo),윤현도(Yun Hyun-Do),서수연(Seo Soo-Yeon),최창식(Choi Chang-Sik),최기봉(Choi Ki-Bong) 한국구조물진단유지관리학회 2006 한국구조물진단학회 학술발표회논문집 Vol.10 No.1
Concrete is deformed by load and subjected to micro damage under allowable deformation because of non-homogeneous property. When micro damage is accumulated, it is cracked and finally fractured. Characterization of AE can be demonstrated the micro damage which it is not discovered from visual observation and it become known to an advantage that was discriminated from the existing nondestructive technique method. The aim of this study was to examine the emission of acoustic signals from four CFRP reinforced concrete beams at cracking and failure processes and the failure mechanism of specimens.
이영오(Lee, Young-Oh),김영주(Kim Yeong-Ju) 세계태권도문화학회 2015 세계태권도문화학회지 Vol.- No.11
The purpose of this study is to identify the cause of decrease in the number of private Taekwondo trainees and explore Taekwondo studio revitalization plan in accordance with the findings. First, Korea Taekwondo Association needs to create a task force team to develop programs which men and women of all ages may participate and to initiate a revitalization support plan. Second, Taekwondo instructors who own Taekwondo studios consider that the lack of programs for adults and teenagers is the cause of low participation in Taekwondo training by adults in Korea. Therefore, it is necessary to diversify the programs provided by Taekwondo studios in order to motivate continuous Taekwondo training and to capture the interests of potential students’ parents and trainees. Third, in order to change the declining trend of Taekwondo training population, Taekwondo instructors should come up with a strategic plan for survival. Meanwhile, Taekwondo-related organizations should actively support Taekwondo studios to increase the market share of Taekwondo in sports market and to extend Taekwondo training period of trainees. In addition, to make Taekwondo more popular, it is needed to attract new trainees and transform Taekwondo into a media-friendly sports game. Fourth, to promote prolonged training period, it is necessary for trainees to change their goals into a more learning-oriented-perspective. Also, educational objectives motivation training even after level-advancement-examination needs to be established. Fifth, it is necessary to transform Taekwondo from training-centered-education to a reinforcement program for physical education classes in schools.