• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.19-23
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• 2004

최근 산업의 고도화와 함께 초고온, 방사선노출 등과 같은 극한환경에서 사용되는 구조물과 MEMS 와 같은 미소 구조물(Hicrostructure)이 많아지고 있으며, 이들의 변형해석을 위한 기존의 접촉식 기법들은 그 한계를 극복해야 할 필요가 있다 해결방안으로 레이저를 이용한 비접촉 측정방식이 많은 발전을 해오고 있으며, 특히, 스페클간섭법(Speckle inteferometry)기반의 변형해석 기술이 가장 뛰어난 기술로 인정받고 있다. 스페클간섭법은 컴퓨터 화상처리기술에 힘입어 전자처리 스페클간섭법(Electronic Speckle Pattern Interferometry : ESPI)으로 발전을 하고 있으며, 자동차와 같은 대형구조물의 변형해석에서 MEMS 구조물과 같은 미소구조물 변형해석까지 그 적용범위가 매우 넓다. 본 논문에서는 ESPI 를 이용한 변형해석분야의 국내외 기술현황 및 적응사례, 발전방향를 소개하였다.(중략)

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.5
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• pp.41-46
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• 2003

Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has the advantage of being able to measure surface deformations of engineering components and materials in industrial areas without contact. The speckle patterns formed with interference and scattering phenomena can measure not only the out-of-plane but also the in-plane deformations. Digital image equipment processes the information included in the speckle patterns and displays the consequent interferogram on a computer monitor. In this study, the experimental results of a canti-levered plate using ESPI were compared with those obtained from the simple beam theory. The ESPI results of the canti-levered plate, analyzed by 4-step phase shifting method, are close to the theoretical expectation. Similarly, out-of-plane displacements of a spot welded canti-levered plate were also measured by ESPI with 4-step phase shifting technique. The phase map of the spot welded canti-levered plate is quite different from that of the canti-levered plate without spot welding.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.32-39
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• 2000

간섭성 광원인 레이저를 이용한 계측 몇 검사기법 중 대표적인 것이 홀로그래피를 이용한 간섭법(Holographic Interferometry, HI)이다. HI는 레이저파장을 단위로 하기 때문에 물체변형에 대해 측정감도가 좋고 비파괴 비접촉의 계측이 가능하다. 또한 삼차원 정보 추출이 가능해서 주어진 간섭무늬로부터 전 영역의 변형을 구할 수 있다는 커다란 장점을 가지고 있다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.7-13
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• 2004

간섭성 광원인 레이저를 이용한 계측 및 검사기법 중 대표적인 것이 홀로그래피를 이용한 간섭법(Holographic Interferometry, HI)이다. HI는 레이저 파장을 단위로 하기 때문에 물체변형에 대해 측정감도가 좋고 비파괴 비접촉의 계측이 가능하다. 또한 삼차원 정보 추출이 가능해서 주어진 간섭무늬로부터 전 영역의 변형을 구할 수 있다는 커다란 장점을 가지고 있다. 그러나 일반적으로 홀로그래피용 필름은 기록 및 현상방법이 성가시고 그 속도 또한 느릴 뿐만 아니라 간섭무늬 패턴도 매우 복잡해서 산업현장 등 실제의 응용에는 현실적인 어려움이 있다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.69-74
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• 2007

The paper proposes a new sonic resonance test for a elastic modulus measurement which is based on time-average electronic speckle pattern interferometry(TA-ESPI) and Euler-Bernoulli equation. Previous measurement technique of elastic constant has the limitation of application for thin film or polymer material because contact to specimen affects the result. TA-ESPI has been developed as a non-contact optical measurement technique which can visualize resonance vibration mode shapes with whole-field. The maximum vibration amplitude at each vibration mode shape is a clue to find the resonance frequencies. The dynamic elastic constant of test material can be easily estimated from Euler-Bernoulli equation using the measured resonance frequencies. The proposed technique is able to give high accurate elastic modulus of materials through a simple experiment set up and analysis.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.630-633
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• 2001

This paper propose electronic speckle pattern interferometry(ESPI) for reliability evaluation of electronic device. Especially, vibration problem in a fan of air conditioner, motor of washing machine and etc. is important factor to design the devices. But, it is difficult to apply previous method, accelerometer to the devices with complex geometry. ESPI, non-contact measurement technique applies a commercial fan of air conditioner to vibration analysis. Vibration mode shapes, natural frequency and the range of the frequency are decided and compared with that of FEM analysis. In mechanical deign of new product, ESPI adds weak point of previous method to supply effective design information.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.34-41
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• 2001

More accurate and fast inspection method for mechanical parts and structure is required to guarantee the safety. Conventional methods using compliance method, eddy current method, ultrasonic wave, acoustic emission for non-destructive testing in mechanical parts and structure have been performed as the method of contact with objects to be inspected. With this reason these methods have been taken relatively much time, money, and manpower. In this study, in order to overcome these shortcomings, we used In-plane Electronic Speckle pattern Interferometry(In-plane ESPI) that was full-field measurement and noncontact method. We detected the cracks of the specimen at a real time and measured the length of the crack by using In-place ESPI system. Finally, we compared this results with conventional microscope method.

• Structural Engineering and Mechanics
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• v.15 no.3
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• pp.367-378
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• 2003

The magnitude of the plastic zone around the crack tip of DENT (Double Edge Notched Tension) specimen and the crack growth length under cyclic loading were measured by ESPI (Electronic Speckle Pattern Interferometry) system. The measured magnitude of plastic zone was compared with the proposed by Irwin and calculated by a nonlinear static method of MSC/NASTRAN. The measured crack growth length by ESPI system was also compared with the obtained data by the image analysis system. From the study, it is confirmed that the plastic zone and crack growth length can be measured accurately with the high-tech equipment (ESPI System).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.91-95
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• 1997

ESPI(Electronic Speckle Pattern Interferometry) is new optical measuring method to be able to measure the surface deformations of engineering components and materials in industrial areas. Conventional measuring method of surface deformation such as the strain gauge have many demerits because it is contact and point-to-point measuring one. But ESPI that is non-contact, whole field measuring method can overcome previous disadvantages. The speckle pattern to be formed with interference phenomena of scattering light from rough surfaces illuminated by laser light have phase information of surface In this study we used this interference phenomena and the phase shifting method to measure the in- plane deformation, together with the use of digital equipment to process the information contained in the speckle pattern and to display consequent inter ferograms. Finally we obtained good agreement between the experimenta results and those of FEM..

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.162-164
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• 2001