• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.273-275
• /
• 2005

Active thermography is being used since several years for remote non-destructive testing. It provides thermal images for remote detection and imaging of damages. Also, it is based on propagation and reflection of thermal waves which are launched from the surface into the inspected component by absorption of modulated radiation. For energy deposition, it use external heat sources (e.g., halogen lamp or convective heating) or internal heat generation (e.g., microwaves, eddy current, or elastic wave). Among the external heat sources, the ultrasound is generally used for energy deposition because of defect selective heating up. The heat source generating a thermal wave is provided by the defect itself due to the attenuation of amplitude modulated ultrasound. A defect causes locally enhanced losses and consequently selective heating up. Therefore amplitude modulation of the injected ultrasonic wave turns a defect into a thermal wave transmitter whose signal is detected at the surface by thermal infrared camera. This way ultrasound thermography(UT) allows for selective defect detection which enhances the probability of defect detection in the presence of complicated intact structures. In this paper the applicability of UT for fast defect detection is described. Examples are presented showing the detection of defects in PCB material. Measurements were performed on various kinds of typical defects in PCB materials (both Cu metal and non-metal epoxy). The obtained thermal image reveals area of defect in row of thick epoxy material and PCB.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.11
• /
• pp.55-61
• /
• 2009

The wall thinning defect of nuclear power pipe is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid. This type of defect becomes the cause of damage or destruction of in carbon steel pipes. Therefore, it is very important to measure defect which is existed not only on the welding part but also on the whole field of pipe. This study use dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. And this study proposes Infrared thermography, which is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. In this paper, defect of nuclear power pipe were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.4
• /
• pp.330-335
• /
• 2013

Since real-time monitoring system like a fault early detection has been very important, infrared thermography technique as a new diagnosis method was proposed. This study is focused on the damage detection and temperature characteristic analysis of ball bearing using the non-destructive infrared thermography method. In this paper, for the reliability assessment, infrared experimental data were compared with the frequency data of the existing. As results, the temperature characteristics of ball bearing were analyzed under various loading conditions. Finally it was confirmed that the infrared technique was useful for real-time detection of the bearing damages.

• Journal of Welding and Joining
• /
• v.32 no.5
• /
• pp.50-57
• /
• 2014

Friction Stir Welding (FSW) is a complex process with several mutually interdependent parameters. A slight difference from known settings may lead to imperfections in the stirred zone. These inhomogeneities affect on the mechanical properties of the FSWed joints. In order to prevent the failure of the welded joint it is necessary to detect the most critical defects non-destructive. Especially critical defects are wormhole and lack of penetration (LOP), because of the difficulty of detection. Online thermography is used process-accompanying for defect detecting. A thermographic camera with a fixed position relating to the welding tool measures the heating-up and the cool down of the welding process. Lap joints with sound weld seam surfaces are manufactured and monitored. Different methods of evaluation of heat distribution and intensity profiles are introduced. It can be demonstrated, that it is possible to detect wormhole and lack of penetration as well as surface defects by analyzing the welding and the cooling process of friction stir welding by passive online thermography measurement. Effects of these defects on mechanical properties are shown by tensile testing.

• Journal of Korean Traditional Oncology
• /
• v.13 no.1
• /
• pp.25-32
• /
• 2008

1. Objective This study was conducted to research a corelation between the Sasang constitutions and primary cancer organs in cancer patient with their thermography. 2. Method We Analyzed the thermography taken from cancer patients and compared it with their cancer origins and Sasang constitution. 3. Result It was found that there are some relationships between the cancer origins and abnormal skin temperature. Also according to the Sasang constitutions of each cancer patient, the lesion of abnormal skin temperature could be differentiated. 4. Conclusion Thermogram can be affected by both the constitution and the primary cancer organs of the patient. To utilize the thermography as a diagnostic or prognostic method of cancer, further studies are needed.

• Fashion & Textile Research Journal
• /
• v.14 no.1
• /
• pp.130-135
• /
• 2012

The purpose of this study was to investigate the variation of regional skin temperature with thermography during exercise. Seven men completed 82-min trials which consisted of rest, exercise of $VO_2$ max 60% and recovery period at $30{\pm}0.5^{\circ}C$ and $60{\pm}5%RH$. Changes in skin temperature due to physical activity varied, depending region of the body. The skin temperature of the chest was significantly lowered and that of the back was significantly increased after exercise period(p < 0.05). There were significant negative relationship between the skin temperature of the chest and thermal comfort sensation, and positive relationship between skin temperature of the back and thermal comfort sensation(p < 0.05). It would be better to keep the chest warm, and the back cool during exercise. The skin temperature changed differently on body site due to exercise, and it was influenced by blood flow, sweating and air movement. This study would be meaningful in that the change of regional skin temperature during exercise was investigated consecutively with thermography. In further study, it would be more realistic to measure physiological response with functional sportswear which applies different functional fabric based on skin temperature.

• Nuclear Engineering and Technology
• /
• v.46 no.2
• /
• pp.225-234
• /
• 2014

Wall-thinned defects caused by accelerated corrosion due to fluid flow in the inner pipe appear in many structures of the secondary systems in nuclear power plants (NPPs) and are a major factor in degrading the integrity of pipes. Wall-thinned defects need to be managed not only when the NPP is under maintenance but also when the NPP is in normal operation. To this end, a test technique was developed in this study to detect such wall-thinned defects based on the temperature difference on the surface of a hot pipe using infrared (IR) thermography and a cooling device. Finite element analysis (FEA) was conducted to examine the tendency and experimental conditions for the cooling experiment. Based on the FEA results, the equipment was configured before the cooling experiment was conducted. The IR camera was then used to detect defects in the inner pipe of the pipe specimen that had artificially induced defects. The IR thermography developed in this study is expected to help resolve the issues related to the limitations of non-destructive inspection techniques that are currently conducted for NPP secondary systems and is expected to be very useful on the NPPs site.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.3
• /
• pp.359-364
• /
• 2010

The objective of this study is to propose an effective method for measurement and analysis of fatigue crack. A technique that can measure the statue of fatigue crack propagation fast and correctly for enhancing safety of constructions and securing reliability is necessary. Moreover, the crack propagation behavior characteristics evaluation technique has to be developed using this technique. In this paper, fatigue crack was caused via the fatigue experiment with repeated load on the CT specimen that is made up of STS304. Fatigue crack propagation was measured by tracing the position of the maximum temperature according to the cycles using infrared thermography. The crack growth characteristics was evaluated by applying the moment values on the measuring area to the measured value. As a result of this study, the possibility that the infrared thermography could be applied to measure the fatigue crack was identified. Moreover, it was identified that fatigue crack propagation have a relationship with the moment value of construction.

• Journal of Ocean Engineering and Technology
• /
• v.26 no.5
• /
• pp.25-30
• /
• 2012

This study examined the use of LIT (lock-in infrared thermography) to detect defects in the welded parts of ships and offshore structures. A quantitative analysis was used with the filtering and texture measurement of image processing techniques to find the optimized experimental condition. We verified the reliability of our methods by applying image processing techniques in order to normalize the evaluations of comparative images that showed a phase difference. In addition, it was found that a low to mid-range intensity of light exposure on the surface showed good results, whereas high exposure did not provide significant results. A lock-in frequency of around 0.1 Hz was satisfactory regardless of the intensity of the light source. In addition, making the integration time of the thermography camera inversely proportional to the intensity of the exposed light source during the experiment provided good results.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.5
• /
• pp.77-81
• /
• 2008

Structural components subjected to high frequency vibrations, such as those used in vibrating parts of gas turbine engines, are usually required to avoid resonance frequencies. Generally, the operating frequency is designed at more than resonance frequencies. When a vibrating structure starts or stops, the structure has to pass through a resonance frequency, which results in large stress concentration. This paper presents the transient thermoelastic stress analysis of vibrating cantilever beam using infrared thermography and finite element method (FEM). In FEM, stress concentration factor at the 2nd resonance vibration mode is calculated by the mode superposition method of ANSYS. In experiment, stress distributions are investigated with infrared thermography and dynamic stress concentration factor is estimated. Experimental result is agreed with FEM result within 10.6%. The advantage of this technique is a better immunity to contact problem and geometric limitation in stress analysis of small or micro structures.