• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.07a
• /
• pp.269-274
• /
• 2000

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.03a
• /
• pp.239-244
• /
• 1998

ESP(Electronic Speckle Pattern Interferometry) is an optical technique to measure deforamtion of engineering components and materials in industrial areas. ESPI, a non-contact and non-destructive measuring method, is capable of providing full-field results with high spatial resolution and high speed. One of important application aspects using electronic speckle pattern interferometry is to generate contours of a diffuse object in order to provide data for 3-D shape analysis and topography measurement. The electronic speckle contouring is suitable for providing measurement range from millimeters to several centimeters. In this study, we introduce the contouring method by modified dual-beam speckle pattern interferometer and a shift of the two illumination beams through optical fiber in order to obtain the contour fringe patterns. Before the experiments, we performed the geometric analysis for dual-beam-shifted ESPI contouring. And by this geometric analysis, we performed the electronic speckle contouring experiment. We used 4-frame phase shifting method with PZT for quantitative analysis of contour fringes. Finally, we showed good agreements between the geometric analysis and experimental results.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.33-40
• /
• 2021

Measuring the compressive strength of concrete is a very important factor in the safety review of concrete structures. Concrete compressive strength measurement methods include destructive and non-destructive methods. The destructive method includes the uniaxial compression failure method, and the non-destructive method includes the rebound hardness method and the elastic wave measurement method. In this study, the type of measurement method and the effect of reinforcing bars inside the concrete were tested to examine the relationship between them. Regardless of the type of specimen, the average compressive strength by the elastic wave measurement method among the three experimental methods was greater than the average compressive strength by the other methods. When the specimen type is the same, the standard deviation of the measured values of the elastic wave measurement method is smaller than that of the other measurement methods, so it can be seen that the elastic wave measurement method does not show large variance in the measured values compared to the other two measurement methods. When the average compressive strength according to the test method for each specimen was compared with the average compressive strength of the compressive failure test method, the average compressive strength was measured to be high in the order of the elastic wave measurement method, the compression failure test, and the rebound hardness method. Since the measured values of the compressive strength of concrete are different depending on the method of measuring the compressive strength of concrete and the presence or absence of reinforcing bars inside the concrete, further research is required considering the effect of various concrete covers.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.6
• /
• pp.173-179
• /
• 2008

This paper aims to calculate age coefficient of ultrasonic pulse velocity by non-destructive test. When concrete compressive strength is measured by non-destructive test, rebound test hammer method is applied to estimate age coefficient depending on the course of time after concrete casting, but ultrasonic pulse velocity method is not applied in the process. Although it is necessary to consider age coefficient with change of ultrasonic pulse velocity of concrete depending on aging, there have been little attempts to apply that method. The experiments were conducted to calculate aging effects which will be applied to establish the formula of measuring concrete strength. As a result of experiments, it was found that ultrasonic pulse velocity showed radical changes depending on concrete hardening in comparison with initial standard values. So, it was concluded that age coefficient must be applied to calculate strength. In conclusion, age coefficient of ultrasonic pulse velocity of concrete was suggested on the basis of experimental results.

• Smart Structures and Systems
• /
• v.6 no.7
• /
• pp.851-866
• /
• 2010

This paper presents a new concept of using PZT (lead zircornate titanate) transducers as a non-destructive testing (NDT) tool for evaluating quality of concrete. Detection of defects in concrete is very important in order to check the integrity of concrete structures. The electro-mechanical impedance (EMI) response of PZT transducers bonded onto a concrete specimen can be used for evaluating local condition of the specimen. Measurements are carried out by electrically exciting the bonded PZT transducers at high frequency range and taking response measurements of the transducers. In this study, the compression test results showed that concrete specimens without sufficient compaction are likely to fall below the desired strength. In addition, the strength of concrete was greatly reduced as the voids in concrete were increased. It was found that the root mean square deviation (RMSD) values yielded between the EMI signatures for concrete specimens in dry and saturated states showed good agreement with the specimens' compressive strength and permeable voids. A quality metric was introduced for predicting the quality of concrete based on the dry-saturated state of concrete specimens. The simplicity of the method and the current development towards low cost and portable impedance measuring system, offer an advantage over other NDE methods for evaluating concrete quality.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 1998.10a
• /
• pp.124-129
• /
• 1998

The ultrasonic pulse measurements can be used to detect the development of cracks in concrete structures and to check deterioration due to frost or chemical action. An estimate of the depth of a visible crack at the surface can be obtained by measuring the transit times that across the crack for two different arrangements of the transducers placed on the surface. In this paper, the concrete cracks that artificially introduced crack of width 1, 2mm and depth 20, 40, 60, 80mm were measured by Tc-To, Direct and Indirect Method. The test results indicate that the Tc-To Method is the most useful in measuring crack of concrete structures. And the crack depth calculated by the Direct and Indirect Method is shown bigger than artificially introduced real crack depth.

• Nuclear Engineering and Technology
• /
• v.29 no.2
• /
• pp.175-180
• /
• 1997

It has been known that eater-side corrosion of fuel rods in nuclear reactor is accompanied with the metallic loss of wall thickness and hydrogen pickup in the fuel dadding tube. The fuel dad corrosion is one of the major factors to be controlled to maintain the fuel integrity during reactor operation. An oxide later thickness measuring device equipped with ECT probe system was developed by KAERI, and whose performance test was carried out in NDT(Non-destructive Test) hot-cell or PIE(Post Irradiation Examination) Facility. At first, the calibration/performance test was executed for the unirradiated standard specimen rod fabricated with several kinds of plastic thin films whose thickness ore predetermined, and the result of which showed a good precision within 10% of discrepancy. And then, hot test us peformed for the irradiated fuel rod selectively extracted from J44 fuel assembly discharged from Kori Unit-2. The data obtained with this device were compared with the metallographic result obtained from destructive examination in PIEF hot-cell on the same fuel rod to verify the validity of the measurement data.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2004.02a
• /
• pp.257-259
• /
• 2004

In this paper measurement method of uranium isotope ratio of uranium-bearing particles in swipe samples was introduced; Swipe sample screening program was proposed on the basis of studying various destructive assay and non-destructive assays. Scanning electron microscope(SEM) equipped with an energy dispersive X-ray fluorescence(XRF) system was applied to locate the deposited uranium-containing particles on the graphite support, particle's composition and size can be identified. Some isotope ratio results were compared with those of other bulk analytical methods; By measuring the same prepared sample, we got the U-particle isotopic ratio data similar to those from IAEA NWAL, indicating that our operation parameters and experimental conditions are viable and can be used for measurement of U-particle isotopic ratio from swipe samples.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.185-187
• /
• 2006

This study deals with characterization and the application of magnetoelasticity as a device which measures existing steel stress. Available method of measuring existing stress needs break the concrete and cut the steel bar. But Proposed method doesn't need to cut the steel bar. A successful application of magnetoelasticity depends on the linearity of the relationship between the elastic and magnetic response due to loading. To investigate the correlation between two, steel bars are loaded in tension under uniaxial loading while the magnetic reading is recorded. Results showed linearity or partial-linearity of the elastic behavior of steel bars in relation to magnetic change. In the paper, the various factors affecting the measurements are also discussed.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.5
• /
• pp.726-732
• /
• 2012

Pipe and Pressure Vessels that is used in power plant and chemical industry have many Internal Defects that is corrosion caused by the flow of fluid. These Internal Defects that have possibility of explosion are very dangerous because it can not see from the outside. This days many companys using NDT method to find an Internal Defect. Most of the NDT methods have limitations that are constraint of shape and materials. But Sheargoraphy have many advantages compared conventional NDT method. It has very fast measuring speed, non-destructive and non contacting measurement. As well as it hasn't constraint of shape and materials. As a paper on the analysis of measurement of error, the important factors were the Shearing Amount and pressure, and discovered measurement of the Internal Defect of the object by using shearography. The optimal Shearing Amount and pressure was discovered and utilized.