• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.541-546
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• 2001

Application of bonding by adhesives can be found in many industries, particularly in advanced technological domains such as the aeronautical and space industries, automobile manufacture, and electronics. Periodic inspection with conventional ultrasonic NDE techniques is capable of indicating the presence and possible location of crack. Continuous ultrasonic attenuation monitoring has potential to supply information. This study used adhesive-bonded single-lap joints specimen to evaluate such possibility by ultrasonic signal processing method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.572-577
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• 2011

The acoustic emission (AE) technique is a well-known non-destructive test technique, both in research and for industrial applications. It is mainly used to monitor the onset of cracking processes in materials and components. Predicting and preventing the crack phenomenon has attracted the attention of many researchers and has continued to provide a large incentive for the use of condition monitoring techniques to detect the earliest stages of cracks. In this research, goal is in grasping features of AE signal caused by crack growth. The envelope analysis with discrete wavelet transform (DWT) is used to find the characteristic of AE signal. To estimate feature of divided into three by crack length, the time waveform and the power spectrum were generated by the raw signals and the transferred signal processed by envelope analysis with DWT.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.308-313
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• 1995

Non-destructive inspection techniques using laser have been broading their application areas as well as growing their measurement skills together with the rapid development of circumferential technology like fiber optics and computer. The remarkable inspection technique using laser speckle, so-called ESPI is aleady on the stage of on-line testing with commercial products in other nations. Especially, this technique is expected to be applied to the nuclear industry. Because it is proper for the vibration measurement and it can be applied to objects of a high temperature. This paper describes the use of the ESPI system for measuring vibration patterns on the reflecting objects. Using this system, high-quality Jo fringers fso that fringe shift algorthms can be used to determine vibration interferograms recorded by the ESPI system.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2009년도 춘계학술발표회 논문집
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• pp.59-63
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• 2009

구조물의 시간경과에 따른 변형 및 성능저하 현상은 인위적 요인 및 시간경과에 따른 지반상태의 변화 혹은 지반 변위요인의 누적에 의해 발생한다. 본 연구에서는 석조 문화재를 3차원 레이저스캐닝시스템에 의한 역공학적 연구에 의해 정밀한 크기, 변위량, 변위방향 등 여러 가지 제원을 구하였다.

• 한국표면공학회지
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• 제36권2호
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• pp.168-175
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• 2003

The purpose of solder plating on chip external electrode is to provide a proper solderability to chips on PCB's. The quantitative or qualitative analysis of solderability has been performed by destructive methods, reflow or flow. Evidently, the solderability tends to depend on the grain structure which is varied with additives. Research on the feasibility of employing electrochemical techniques to characterize the solderability of electroplated tin - lead, with respect to the additives, was non destructively performed. The deposit morphology and the polarization behavior of electrolytes containing proprietary additives were evaluated to investigate the soldering degradation. The plated panels from synthetic electrolyte were analyzed according to % Sn, plating thickness, deposit appearance, grain structure, solderability and cyclic voltammetry.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.1021-1024
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• 2008

콘크리트의 내부 공극을 검출로 열화상기법 적용시 일반적으로 쓰이는 열원인 자연광, 할로겐램프, 열풍과 달리 본 논문에서는 근적외선 히터를 이용하였다. 이 기법에 의한 실험 결과를 각 공극 깊이와 공극 크기별로 무차원 상대 온도로 나타내어 콘크리트 내부 공극의 식별 가능 여부를 조사하였다. 본 실험의 결과, 할로겐램프나 원적외선램프 열원에 비하여 대상 물체를 단시간 내에 가열하여 콘크리트 내부 공극 검출 시간이 상대적으로 짧은 것으로 확인되었다.

• Structural Engineering and Mechanics
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• 제56권3호
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• pp.409-422
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• 2015

In this paper, the Multi-Swarm Fruit Fly Optimization Algorithm (MFOA) is presented for structural damage identification using the first several natural frequencies and mode shapes. We assume damage only leads to the decrease of element stiffness. The differences on natural frequencies and mode shapes of damaged and intact state of a structure are used to establish the objective function, which transforms a damage identification problem into an optimization problem. The effectiveness and accuracy of MFOA are demonstrated by three different structures. Numerical results show that the MFOA has a better capacity for structural damage identification than the original Fruit Fly Optimization Algorithm (FOA) does.

• Structural Engineering and Mechanics
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• 제30권4호
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• pp.481-500
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• 2008

In this paper, a model updating technique in dynamics is used to identify elastic properties for pultruded GFRP-Glass Fiber Reinforced Plastic framed structural systems used in civil construction. Traditional identification techniques for composite materials may be expensive, while this alternative approach allows to identify several properties simultaneously, with very good precision. Furthermore, the procedure of a non-destructive type has a relatively simple implementation. Properties describing the mechanical behavior for beam and shell finite element modeling are identified. The used formulation is based on the minimization of eigensolution residuals. Important points concerning model updating procedures have been observed, such as the particular vibrational behavior of the test structure, the modeling strategies and the optimal placement of the sensors in the experimental procedure. Results obtained by experimental tests show the efficiency of the proposed procedure.

• Preventive Nutrition and Food Science
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• 제3권2호
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• pp.203-209
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• 1998

The development of methods for the identification of irradiated foods helps enforce national and international regulations on labelling to ensure the consumer's free choice to buy irradiated or unirradiated foods. and the availabilityof such methods may assist the promotion of international trade in irradiated food products and help prevent abuse of the technology. A number of approaches to determine the physical , chemical, microbiological and biological changes that occur in foods treated with ionizing radiation have been studied. However no single method is universally applicable. Among physical measurements, the leading methods of indentification are electron spin resonance (ESR) spectroscopy and thermoluminescence(TL). ESR is an established non-destructive method for the analysis of free radicals from their traps and TL is the emission of light from irradiated mineral extracts by heating. Viscosity of carbohydrate polymers by causing chain breaks by irradiation, measuring the impedance of potatoes and detection of gases produced radiolytically are promising techniques for identification purposes. Irradiated water-containing foods show significant supercooling when monitored with a differential scanning calorimeter (DSC), which can be applied to identifying irradiated ones.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 국제표면실장 및 인쇄회로기판 생산기자재전:전자패키지기술세미나
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• pp.17-25
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• 2004

During the past few years, advances have been made in both in X-ray tube and detector technologies. The field of microfocus radioscopy has been established as an important testing process and has expanded into many new industrial applications that require quality control or process optimization. The first nanofocus and multifocus X-ray systems have become available with a focal spot of .5 micron. In the existing range of microfocus X-ray tubes, further improvements have been achieved as well, such as increased long term stability of intensity position constancy. Software, image processing and manipulation techniques have all progressed as well, allowing X-ray to become a formidable non-destructive inspection method for manufacturers in virtually every industry, especially those involved with Electronic Packaging and SMT.