Advanced Nondestructive Evaluation I

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Authors: Jung Yul Park, Juno Park, Sang Dae Kim, Dong Jun Lim
Abstract: The changes in thermographic pattern were studied, in patients with persistent back and leg pain after surgery, to validate its significance in evaluating the clinical status following percutaneous radiofrequency (PRF) lesioning on dorsal root ganglion. A total of 90 patients with persistent back and leg (52 males, 38 females, mean age 46.2 years) with more than 6 months of duration following lumbar surgeries were enrolled into study. Thermography was performed before and after PRF procedures. PRF procedures were percutaneously done with C-arm guidance and adjustments from physiologic monitoring. Assessments included the clinical symptoms, signs and changes of thermographic pattern before and after PRF procedure. Minimal follow up period was 6 months. All patients tolerated the RF procedures without complications. Thermographic findings before procedures were agreeable to clinical and radiographic findings in 81(90%) of patients. PRF procedure provided substantial improvement of pain (>50% pain reduction) in 69(76.7%) and 63(70%) at 1 and 6 months following procedures. Thermographic findings in 80(88.9%) of these patients seemed to correlate with clinical improvement. However, 12 patients (13.3%) showed no significant thermographic changes despite clinical improvement. Clinical factors that were not statistically significant but were related to better outcome were younger age, unilateral pain, no significant dysesthesia, less number of operations, no instrumentation. Results of this study indicate that thermography may have a specific role in evaluating these patients, especially when comparing with clinical status.
Authors: Jung Yul Park, Juno Park, Sang Dae Kim, Se Hoon Kim, Dong Jun Lim
Abstract: Tests for successful surgical results for refractory palmar hyperhidrosis in the past usually involve starch test, plethysmograpy, and direct measurement of skin temperature. However, these tests are either inconvenient, inadequate or unable to be used during operation. Authors have used IR thermography during percutaneous radiofrequency sympathectomy to verify its usefulness as guide for evaluating the successful results. A total of 14 patients with persistent palmar hyperhidrosis were included. Average age was 28.2 years (range 21-36 years). Average duration of symptom was 24 months. All procedures were percutaneously performed under local anesthetics. Procedures include position the patient in prone position and introduction of three 21-guage RF TIC needles with 10 mm bared tip electrode to T2 and T3 ganglion in each side under C-arm guidance. After obtaining correct placement of electrode, a series of three lesions at each level with 90 °C for 120s were done. Successful lesioning was confirmed by from marked widening of pulse amplitude with an increase in hand skin temperature (>2 °C) by thermographic examination during operation. Average follow up period was 14.4 months. All patients tolerated the procedure and responded immediately to have dryness sensation of hands, most of which remained for rest of follow up period. Twelve patients (85.7%) reported as having about 80% of initial responses and one patient about 60% at 12 months postoperatively. Another patient who lost about 30-40% of initial response had undergone second procedure 3 months later with similar success. There were no complications related to the procedures and there were no rebound phenomenon. With regards to the role of intraoperative thermography in determining the successful results, it seems to provide clear-cut information whether these patients received proper treatments for future successful outcome. Thus, authors believe IR thermogrpahic examination is simple, feasible way of demonstration of completeness of sympathectomy in object way during surgical procedure that can be used as a guide for successful outcome.
Authors: Seok June Oh, Du Hwan Chung, Han Seo Ko
Abstract: Demand of a LCD-TV is remarkably increasing with development of the LCD technology in these days. However, there are thermal problems to improve efficiency for the LCD-TV. Thus, the thermal problems such as convection and conduction heat transfer characteristics have been analyzed for the LCD-TV using an IR (Infrared) camera. Measured temperatures in an outer side of the front panel have been compared with results of an inner side of the front panel using the IR camera and T-type thermocouples, respectively. Equations have been derived for the temperature distribution of the inner side of the LCD panel by developed multiple regression methods including variables for ambient temperatures and measured outer temperatures of the front panel of the LCD-TV.
Authors: Lan Chung, In Kwan Paik, S.H. Cho, Young Sook Roh
Abstract: The corrosion reinforcing steel in concrete structures is detrimental to its service life. In order to increase lifespan and maintain serviceability, a qualitative measurement technique that can measure the extent of corrosion of reinforcing steel needs to be developed. While considerable researches have been carried out focusing only on detecting corrosion and restraining the progress of corrosion, a qualitative measurement technique that can measure the amount of corrosion in rebar need to be developed. The purpose of this research is to develop a new technique to measure the corrosion level of rebar using accumulated thermal data. Accumulated thermal data were gathered using infrared camera and digitized to distinguish the difference between various corrosion levels of rebar. The test results showed that the higher level of corrosion displays the higher level of temperature. Temperature of reinforcing steel is not severely affected by ambient temperature, however, concrete surface temperature increased as ambient temperature increased.
Authors: Joon Hyun Lee, Jeong Guk Kim
Abstract: The fracture behavior of Nicalon fiber reinforced calcium aluminosilicate (CAS) glass-ceramic matrix composites (Nicalon/CAS) was investigated with the aid of a nondestructive evaluation (NDE) technique. Infrared (IR) thermography was employed for unidirectional Nicalon/CAS composite specimens. During tensile testing, an IR camera was used for in-situ monitoring of progressive damages of Nicalon/CAS samples. The IR camera provided the temperature changes during tensile testing. Microstructural characterization using scanning electron microscopy (SEM) was performed to investigate the fracture mechanisms of Nicalon/CAS composites. In this investigation, the thermographic NDE technique was used to facilitate a better understanding of the fracture mechanisms of the Nicalon/CAS composites during tensile testing.
Authors: Su Young Kim, Doo Ik Lee, Keon Sik Kim, Dong Ok Kim, Young Kyoo Choi, Do Young Choi, Sabina Lim, Jae Dong Lee, Yun Hoo Lee
Abstract: Central poststroke pain can occur as a result of lesion or dysfunction of the brain from stroke, and may influence the autonomic nervous system to regulate the vasomotor activity which could result in the lowered skin temperature. In order to assess CPSP objectively, seventy patients with CPSP were evaluated as their pain with VAS pain score and the skin temperature of pain site by infrared thermography before and after pain treatment. And evaluated correlation between changes of temperature and VAS. The skin temperature of pain site was significantly lower than non-pain before treatment and improved after treatment(p<0.05), in accordance with significant improvement of VAS pain scores after treatment(p<0.05). And there was highly correlation between the changes of temperature and VAS(p<0.05). Therefore, it is suggested that the infrared thermography is very useful device for the evaluation of CPSP and its treatment.
Authors: Won Tae Kim, Man Yong Choi, Jung Hak Park
Abstract: This study is aimed to analyze the thermal imaging patterns presented by infrared(IR) thermography at which the metal with internal defects are thermally heated. Through the knowledge of non-destructive testing which infrared thermography can be applied to detect the defects inside the materials, there are two materials experimented; one is stainless steel and the other is cast-iron. Thermally, each material of specimens is heated at the base of the material and kept with constant temperature, The artificial defects in the specimen are formulated. Under the shape and location of the defects, temperature profiles are also measured and validated using the computer simulation. It is concluded that the characteristics of thermal patterns obtained from IR thermography are consistent with those of measurement and computations.
Authors: Kenji Machida, Shohei Miyagawa
Abstract: The thickness dependency of the temperature image obtained by an infrared thermography was investigated using specimens with three kinds of materials and four kinds of the thickness of the specimen. Then, the infrared hybrid method was developed to separate individual stress components. However, it had the influence by heat conduction in the infrared stress measuring method. Therefore, an error will occur in the infrared hybrid analysis. Then, the system which corrected the error by the inverse analysis was developed. Thereby, the accuracy of the stress intensity factor was able to be raised. Furthermore, the accuracy of hybrid method considering to heat conduction was discussed in comparison with the 3-D finite-element analysis and 2-D hybrid method.
Authors: Ho Yeol Zhang, Bo Young Cho, Han Sung Kim, Yong Eun Cho
Abstract: Whiplash injury is produced by the hyperextension of the neck followed by flexion. These patients have no abnormality in radiologic evaluation. We collected 39 patients and divided into two groups; Group 1 (neck pain without radiculopathy) and Group 2 (neck pain with radiculopathy). Thermal differences at neck and arm were checked with IR thermography. 1 patient was taken the IR thermography periodically until recovery from his symptom. Group 1 showed that subjective painful area on the neck was changed to hyperthermic, but the arm temperature was normal. Group 2 showed that subjective painful area on the neck was changed to hyperthermic, and painful arm was changed hyperthermic, which can be differentiated from hypothermic change in cervical disc herniation patients. Thermal differences were gradually reduced with the same consequence of the patient’s symptom recovery. IR thermography can be used to diagnose the whiplash injury and also to determine a symptom recovery. It is possible to differentiate the whiplash injury with radiculopathy and pre-existing cervical disc disease.
Authors: Chung Hee Park, Myoung Hee Shim, Huen Sup Shim
Abstract: The purpose of this study was to develop the warm-up suit that is comfortable as well as has good thermal performance. The function of warm-up suit is to keep the body warm and thus to lose it’s weight by sweating. Ceramic powders, such as zirconium and magnesium oxide have been incorporated into the textile structures to utilize the far infrared radiation effect of ceramics, which heat substrates homogeneously by activating molecular motion. Thermal manikin tests were conducted to determine the clothing insulation and evaporative resistance of the selected warm-up suits. Also, the far IR emission effects of ceramics containing laminate on the body heat transfer were evaluated with the thermogram data using IR camera. The results showed that the ceramics inside laminate slightly increased the thermal insulation and the evaporative resistance. Thermogram showed that when the fabric was heated with the thermal manikin, surface mean temperatures of fabrics were increased as the ceramic incorporated, and the heat storage performance was confirmed.

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