• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.282-289
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• 2010

Most nondestructive testing techniques require good contact between the sensor and tested concrete surface to obtain reliable data. But the surface preparation is often very time and labor consuming due to the rough surface or limited access of concrete structures. One approach to speed up the data collection process is to eliminate the need for physical contact between the sensor and tested structure. Non-contact air-coupled sensing technique can be a good solution to this problem. An obvious advantage of the non-contact air-coupled sensing technique is which can greatly speed up the data collection in field and thus the damage detection process can be completed very rapidly. In this article, recent developments in non-contact air-coupled sensing technique for rapid detection of damages in concrete structures are summarized to evoke interest, discussion and further developments on this technique to a NDT research community in Korea. It is worth noting that the works in this article have been published in the types of thesis, proceedings, and journals. All published sources are cited in the text and listed in reference.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.63-70
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• 2017

As the Non Destructive Test (NDT) for the welded structure, PT(Penetration Test). MT(Magnetic Test), RT (Radioisotope Test) and UT(Ultrasonic Test) methods are widely used in practice. These NDT methods have been developed toward high efficiency, low cost, real time, and high precise new NDT. For example, RT methods are developed to CT(Computed Tomography)and DR(Digital Radiography), and UT metheds are developed into Phased array, Guide wave, TOFD method. Moreover, the Infrared thermography and Laser ultrasonic technique are newly developed for applying in high temperature objects as the non-contact NDT methods. In this review paper the new high efficiency NDT methods for the welded structure are introduced and the trend of NDT rules applying in welded structure are described.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.9
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• pp.52-58
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• 1995

Conventional measurement methods for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been performed as the methods of contact with objects to be inspect, but those methods have been taken relatively much time to be inspected. Holographic interferometry which is a non-contact optical measurement method using a coherent light can overcome these demerit, and also has an advantage that the quantitative measurement of small deformation for large areas can be accomplished at a time with high precision. In this paper the comparisons of the experimental results form holographic interferometry with those from the finite element method(FEM) and the analytical solutions of the elastic equation are discussed.

• Journal of the Korean Society of Visualization
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• v.19 no.3
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• pp.54-62
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• 2021

This study has investigated the 3-D deflection characteristics of a flexible plate levitated by non-contact grippers using SPIV method. The measuring instrument consisted of a flexible plate located under four non-contact grippers and two cameras at the bottom of a transparent acrylic plate. Measurements were made on two materials (PVC and PC) for the plate with 50×50 cm2 area and 1 mm thickness. The deflection characteristics and flatness vary depending on the plate material, the gripper position and the air flow supplied to the gripper. For the material of PVC, the overall defection is convex. As the gripper position goes outward from the plate center, the upmost bending point also moves to the outside of the plate with the flatness increasing. However, the air flow rate does not affect the deflection pattern except for the small increase of flatness. For the material of PC, the shape of deflection changes from convex to concave as the gripper position goes out. The flatness is the highest at the point of transition from convex to concave, but the air flowrate has little effect on the flatness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.273-278
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• 1993

Conventional measurement methods for non-destructive testing(NDT) in nuclear power plants other industrial plants have been performed as the methods of contact with objects to be inspect, but those methods have been taken relatively much time to be inspected. Holographic interferometry which is a non-contact optical measurement method using a coherent light can overcome these demerit, and also has an advantage that the quantitative measurement of small deformation for large areas can be accomplished at a time with high precision. In this paper the comparisons of the experimental results from holographic interferometry with those form the finite element method(FEM) and the analytical solutions of elastic equation are discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.377-382
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• 1995

Conventional measurement methods using ultrasonic wave or x-ray, eddy current for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been performed as the method of contact with objects to be inspected. With this reason these methods have been taken relatively much time and the inspected area is limited by the location of probe or film. But holographic interferometry which is a non-contact optical measurement method using a coherent light source has an advantage that the quantitative measurement can be performed at a time. In this paper a new method using holographic interferometry and image processing for detecting internal flaws of pressure vessels is presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.609-610
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• 2012

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.7-11
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• 2012

For fault detection about the abrasion stage of rotational machineries under the dynamic loading conditions unlike the traditional diagnosis method used in the past decade, the infrared thermographic method with its distinctive advantages in non-contact, non-destructive, and visible aspects is proposed. In this paper, by applying a rotating deep-grooved ball bearing, passive thermographic experiments were conducted as an alternative way to proceeding the traditional fault monitoring on spectrum analyzer. As results, the thermographic experiment was compared with the traditional vibration spectrum analysis to evaluate the efficiency of the proposed method. Based on the results obtained as NDT, the temperature characteristics and abnormal fault detections of the ball bearing according to the abrasion stage were analyzed.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.4
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• pp.398-413
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• 2011

For railway safety, it is very important to detect damages of rails at their early stage because any undetected damage in a rail can break the rail and cause a serious railway accident. In this paper, several NDT applicable to rail inspections are described. Major damage types in rails are discussed first and the rail inspection technology using conventional piezoelectric ultrasonic transducers, which is widely adopted for damage detection of rails, is explained. Other NDT being researched or tested for rail inspection are also discussed as complementary technologies to the concurrent contact type ultrasonic inspection. Characteristics of each rail inspection technologies are evaluated in order to provide requirements for future development of a new rail inspection method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.35-39
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• 2006

With a growing concern about the state of infrastructure worldwide, the demand for the development of reliable nondestructive testing techniques (NDT) is ever increasing. Among possible NDT techniques. microwave method is proven to be effective in fast and non-contact inspection of concrete structures and inclusions inside concrete. It is also found that the microwave method has a potential in detecting the delamination between fiber reinforced polymer (FRP) plate and concrete. On the other hand, ultrasonic method can be another way to find the delamination. In this paper, the research work needed for the development of a reliable microwave method and ultrasonic method is studied in actual measurements of concrete specimens reinforced with FRP. Concrete specimens are made with FRP and artificial delamination inside. A microwave measurement system with horn antennas with high center frequency and broad frequency bandwidth are used to image inside concrete specimens for the detection of debonding. between concrete and FRP. Also, the equipment of ultrasonic method which is commercialized are used at the same condition. Both of the results are analyzed in comparison of each other. Microwave and ultrasonic methods have been used for the detection of debonding between concrete and fiber-reinforced plastic (FRP).