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충격 공진법에 의한 대소 경계조건하 콘크리트 블록 내부결함 신호의 해석
박석균,윤석수,Park, Seok-Kyun,Yoon, Seok-Soo 한국콘크리트학회 1999 콘크리트학회지 Vol.11 No.1
본 연구는 비파괴 검사방법인 충격 공진법을 이용하여 결함을 갖는 콘크리트 시험체로부터의 반사신호를 정량적으로 해석하기 위한 연구이다. 충격 공진법은 비교적 저주파의 강한 에너지를 콘크리트내에 가하여 그 반사신호로부터 결함이나 경계층 등을 조사하기 때문에 굵은 골재 등을 포함하고 중량물인 콘크리트 구조물의 탐사에 유용하다. 그러나, 보나 기둥 등의 작은 경계를 갖는 콘크리트 시험체를 대상으로 할 경우에는 각 경계로부터 수평방향을 왕복하는 R-파의 영향이 크기 때문에 결함 또는 경계층으로부터의 반사신호인 수직방향으로부터의 P-파의 세기가 충분히 크지 못하면, 결함 등으로부터의 신호를 검출하기 어렵게 된다. 따라서, 본 연구에서는 시험체의 경계조건과 결함의 위치에 따라 발생 가능한 각 진동모드를 정량적으로 해석하는 방법을 연구하여 결함으로부터의 신호를 검출하는 방법에 대해 검토하였다. 그 결과, 각모서리의 길이가 50cm 이내의 작은 경계조건과 50cm의 깊은 두계를 갖는 콘크리트 시험체내의 결함에 대해서도 콘크리트가 부배합 조건이고 결함의 깊이가 30cm이내일 경우 정량적 탐사가 가능하며, 각 모서리의 크기가 충분히 큰 대형 시험체 조건에서는 보다 용이하고 폭넓게 다양한 조건의 결함 등에 대한 정량적 참사가 가능하였다. Impact resonance testing was carried out on small and large concrete blocks containing several types of artificial flaws respectively. Quantitative analysis of the observed peak frequencies in the impact resonance tests identifies the possible normal modes of concrete blocks containing flaws. and enables to determine the depth and size of the flaws in concrete blocks. In this study, concrete can be treated as a homogeneous and isotropic material. The flaw size and location at each section of artificial flaw series in small and large concrete blocks, determined through two-dimensional scanning of impact point and real-time fast Fourier transform, are in good agreement with real size location, respectively. Consequently, quantitative analysis method of vibration modes in the impact resonance tests, which can be applied for homogeneous and isotropic material, can be useful for the detection of flaws in any case of small and large concrete blocks in this study.
층간 매질재료변화에 따른 콘크리트 내부 철근검출특성에 관한 전자파 레이더 모의해석
박석균 ( Park Seok Kyun ) 한국구조물진단유지관리공학회 2005 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.9 No.2
This study introduces an advanced simulation model of radar response on reinforcing bars and each boundary interfaces according to material changes of intermediate boundary mediums in reinforced concrete. In this model, the electromagnetic wave was assumed to have two different propagation modes at the interface (normal incidence and oblique incidence) depending on the subsurface objects. An approach has also been proposed to analyze the attenuation in each interface which has different electromagnetic properties and the horizontal resolution of target object(reinforcement bar). As the results, it is concluded that this simulation analysis technique can be used to analyze radar response on reinforcing bars and each boundary interfaces according to material changes of intermediate boundary mediums in reinforced concrete.
박석균 ( Park Seok-kyun ),최욱 ( Choi Ook ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.7 No.1
Electromagnetic wave radar method and electromagnetic induction method are applied many times for detecting reinforcing bars in concrete nondestructively in case of diagnosis of concrete structures. By the way, these methods have an error accompanying tested reinforcing bars in concrete because there are many uncertainty factors. So, it is necessary to study for an error of these methods affected by these uncertainty factors. Errors accompanying tested position and cover depth of reinforcing bars in concrete are analyzed in this study.
초음파 토모그래피법을 이용한 콘크리트 내부의 형상별 모의 공동의 검출 특성
박석균 ( Park Seok Kyun ),최욱 ( Choi Ook ) 한국구조물진단유지관리공학회 2002 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.6 No.2
Voids created with concrete construction or deterioration result in serious weakness from the aspects of both structural and durable function. Ultrasonic tomography method was used for detecting pattern of artificial voids in concrete in this · study. Experimental investigation was carried out for three types (patterns) of artificial void in concrete. The effect of curing period of concrete was also investigated. As a result, it has been verified that ultrasonic tomography method used in this study is effective to detect artificial void and shape of it in concrete. The longer the curing period of concrete is, the better the detection accuracy of void pattern can be obtained.
초음파 토모그래피법과 사각법에 의한 콘크리트 내부공동 검출
박석균 ( Park Seok Kyun ),허재영 ( Heo Jae Young ),이원홍 ( Lee Won Hong ) 한국구조물진단유지관리공학회 2008 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.12 No.2
Cavities created with concrete construction or deterioration result in serious weakness from the aspects of both structural and durable function. In this study, ultrasonic pulse velocity method was used for detecting artificial cavities in concrete. Tomography method and semi-direct method were selected and applied for testing of ultrasonic pulse velocity. Experimental investigation was carried out for two type artificial cavities (a rectangular parallelepiped and a regular hexahedron) in concrete. As a result, it has been verified that ultrasonic tomography method and semi-direct method are almost the same results of detecting shape of cavities in concrete.