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후방복사된 Leaky Lamb Wave를 이용한 Steel과 Rubber 와의 접합계면 특성 평가
송성진(Sung-Jin Song),정민호(Min-Ho Jung),김영환(Young H. Kim),권성덕(Sung-Duk Kwon) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8
Multi-layered material has been widely used for high performance materials with advanced properties required for the critical parts of the structures. The characterization of adhesive property in multi-layer materials has been hot issue for a long time. In order to evaluate adhesive properties, we constructed fully automated system for the backward radiation of leaky Lamb wave, and all rf waveforms and frequency spectra could be analyzed. The backward radiation profiles were obtained for the bare steel plate and plates with rubber-loading. The rf waveforms and frequency spec a of backward radiation show the characteristics of involved leaky Lamb wave modes. The rubber-loading decreases the amplitude of profile, and peak position in profile was shifted. As thickness of rubber-loading, the amplitude of profile at the incident angle of 15.4℃ exponentially decreased. Scanning the incident position over the partially rubber-loaded specimen shows good agreement with the actual rubber-loading. Unloading region could be precisely determined by taking reasonable threshold level of backward radiation amplitude. The backward radiation of leaky Lamb wave has great potential to evaluate the adhesive condition as well as material properties of plates.
초음파 전파특성을 이용한 열가소성 합성수지의 열화 평가
전우상(Woo-Sang Jeon),김기진(Gi-Jin Kim),권성덕(Sung-Duk Kwon) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.2
경제성과 함께 다양한 기능성으로 유리 및 금속제를 대체하고 있는 고분자 합성수지인 플라스틱(plastic) 재료의 열화(thermal degradation) 및 열적 특성을 비파괴적으로 평가하기 위하여 초음파의 전파특성(속도 및 감쇠)이 사용되었다. 플라스틱 재료중 범용 열가소성 재료인 높은 투명도의 아크릴 수지(PMMA)에 대해 유리전이온도(Tg) 범위내에서 열화온도 및 열화시간에 따른 다양한 열화시편에 대해 전파특성 변화가 측정되었다. 열화가 진전될수록 감쇄는 증가하였고 속도는 감소함을 보였으며, 초음파 전파특성의 측정을 통해 열가소성 플라스틱 재료의 정량적 열화평가 및 유리전이온도(Tg) 영역의 정성적 추정이 가능하였다. A nondestructive ultrasonic technique was applied to evaluate the thermal characteristics and degradation of synthetic polymer resin (plastics) with better cost-effectiveness and functionality than glass and metal. Thermoplastic and transparent acrylic resin (PMMA) specimens were annealed at below the glass transition temperature (Tg), and the propagation characteristics (attenuation and velocity) were measured. The attenuation increased and the velocity decreased with thermal degradation. The results showed that the thermal aging of the specimens could be evaluated quantitatively and that the Tg could be evaluated qualitatively.
후방복사된 초음파를 이용한 터빈 블레이드 재료의 부식 열화특성 평가
송성진,김영환,배동호,정민호,권성덕,Song, Sung-Jin,Kim, Young-H.,Bae, Dong-Ho,Jung, Min-Ho,Kwon, Sung-Duk 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11
The corrosion degradation characteristics of the 12Cr alloy steel, which is widely used in fossil power plants as a turbine blade material, are evaluated nondestructively by use of the backward radiated Rayleigh surface wave. In order to evaluate corrosion degradation characteristics, we constructed automated system for the backward radiation, and the frequency dependency of the Rayleigh surface wave is investigated indirectly by measuring the angular dependency of the backward radiation of the incident ultrasonic wave in the specimens. The velocity of the surface wave decrease as the increase of the aging time in the backward radiation profile, which seems to result from the increase of the effective degrading layer thickness. And, amplitude of the surface wave increase as the aging time, which seems to result from the increase of the intergranular corrosion. The result observed in this study demonstrates high potential of the backward radiated ultrasound as a tool for the nondestructive evaluation of the corrosion degradation characteristics of the aged materials.
하수관용 HDPE배관 내 결함 탐상을 위한 초음파 특성 분석 연구
임연수(Yeon Soo Lim),염윤택(Yun Taek Yeom),김학준(Hak Joon Kim),송성진(Sung Jin Song),권성덕(Sung Duk Kwon),강성식(Sung Sik Kang) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A land depression in urban problem is occured in the world. It causes a huge economic and human damage. it is mostly caused by a leakage of sewer pipe. Today, sewer pipe inspections are conducted in visual inspection by human or robots. In that case, visual inspection can not detect cracks in water. To detect cracks completely, a visual inspection should be replaced by other nondestructive inspections. In this study, we tried to find defects in a sewer HDPE pipe by using ultrasound inspection. we made a artificial defect pipe specimen and fabricated scanner system which use a pulse-echo method. We checked each crack ultrasonic signal of cracks. As a result, There are differences in each crack signal because of sewer HDPE pipe shape so each crack signals could be distinguished by each wave characteristics.
원전 격납건물 내 공극 검출을 위한 비파괴평가 기법 연구
최영원(Yeong-Won Choi),염윤택(Yun-Taek Yeom),김학준(Hak-Joon Kim),송성진(Sung-Jin Song),류승우(Sung-Woo Ryu),김훈희(Hun-Hee Kim),박재석(Jae-Suk Park),권성덕(Sung-Duk Kwon) 한국비파괴검사학회 2020 한국비파괴검사학회지 Vol.40 No.6
원전 격납건물(Containment liner plate; CLP)은 원통형 벽체와 상부 덮개인 돔으로 구성된 구조물로서 사고에 의한 방사성 물질의 누설을 막기 위해 콘크리트 및 라이너 플레이트로 구성되어 있다. 원전 격납건물에서 발생하는 결함은 주로 라이너 플레이트의 부식 및 콘크리트의 공극이며, 그중 콘크리트 내 공극 검사에 대한 연구는 미흡한 실정이다. 본 논문에서는 원전 격납건물의 콘크리트 공극을 검출하기 위해 원전 격납건물 모사 시험편을 제작하였고, 위상배열 초음파기법(Phased array Ultrasonic Testing; PAUT) 및 충격반향기법(Impact echo)을 이용하여 원전 격납건물의 콘크리트 공극 검사 연구를 진행하였다. 위상배열 초음파기법에서는 신호의 세기를 비교 · 분석하였고, 충격반향기법에서는 비접촉식 센서를 이용하여 데이터를 수집하였으며 주파수 스펙트럼의 비교 · 분석을 통해 원전 격납건물의 콘크리트 공극 검출을 위한 비파괴평가 기법 연구를 시도하였다. The containment liner plate (CLP) is a structure consisting of a cylindrical wall and dome acting as an upper cover and which is composed of concrete and liner plate to prevent leakage of radioactive materials resulting from accidents. Defects in CLP are primarily corrosion of liner plate and void in concrete and among them, a study of inspecting void in concrete is insufficient. In this study, a CLP specimen was fabricated to inspect the concrete voids of a CLP, and a void inspection study was conducted using phased array ultrasonic testing (PAUT) and impact echo. In PAUT, the intensity of the signal was compared and analyzed. With the impact echo method, data were acquired using a non-contact sensor, and a non-destructive evaluation method was used to detect concrete voids in the CLP through comparison and analysis of the frequency spectrum.