• Journal of Magnetics
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• v.21 no.1
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• pp.57-60
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• 2016

Non Destructive Testing (NDT) methods that are capable of detecting the wall thinning and defects through insulation and cladding sheets are necessary. In this study we developed a Pulsed Eddy Current (PEC) system to detect wall thinning of ferro magnetic steel pipes covered with 95 mm thick fiber glass thermal insulator and shielded with aluminum plate of thickness 0.4 mm. In order to confirm the thickness change due to wall thinning, two different sensors, a hall sensor and a search coil sensor were used as a detecting element. In both the cases, the experimental data indicates a considerable change in the detected pulse corresponding to the change in sample thickness. The thickness of the tube was made to change such as 2.5 mm, 5 mm and 8 mm from the inner surface to simulate wall thinning. Fast Fourier Transform (FFT) was calculated using window approach and the results were summarized which shows a clear identification of thickness change in the test specimen by comparing the magnitude spectra.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.90-95
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• 2014

Local wall thinning is a point of concern in almost all steel structures such as pipe lines covered with a thermal insulator made up of materials with low thermal conductivity(fiberglass or mineral wool); hence, Non Destructive Technique(NDT) methods that are capable of detecting the wall thinning and defects without removing the insulation are necessary. In this study we developed a Pulsed Eddy Current(PEC) system to detect the wall thinning of Ferro magnetic steel pipes covered with fiber glass thermal insulator and shielded with Aluminum plate. The developed system is capable of detecting the wall thickness change through an insulation of thickness 10cm and 0.4mm aluminum shielding. In order to confirm the thickness change due to wall thinning, two different sensors, a hall sensor and coil sensor were used as a detecting element. In both cases, the results show a very good change corresponding to the thickness change of the test specimen. During these experiments a carbon steel tube of diameter 210mm and a length of 620mm, which is covered with insulator of 95mm thickness was used. To simulate the wall thinning, the thickness of the tube is changed for a specified length such as 2.5mm, 5mm and 8 mm from the inner surface of the tube. A 0.4mm thick Aluminum plate was covered on the Test specimen to simulate the shielding of the insulated pipelines. For both hall sensor and coil detection methods Fast Fourier transform(FFT) was calculated using window approach and the results for the test specimen without Aluminum shielding were summarized which shows a clear identification of thickness change in the test specimen by comparing the magnitude spectra. The PEC system can detect the wall thinning under the 95 mm thickness insulation and 0.4 mm Al shielding, and the output signal showed linear relation with tube wall thickness.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.597-602
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• 2004

In practical applications of guided wave techniques, it is very important but also difficult to identify the propagating modes, and it is preferred to generate and detect a single or less dispersive mode. Also the noncontact method is required in the automated field application. So this paper considers a non-contact guided wave technique with enhanced mode-selectivity, where a laser beam illuminated through arrayed line slits is used as the transmitter and the air-coupled transducer is used as the receiver. The line arrayed laser illumination is a wavelength matching technique that ran generate only a few modes. The air-coupled transducer detects the leaky wave of the propagated guided wave, and by tuning its detection angle we ran detect the selected single mode. Experimental results for a 1mm thick aluminum plate proved the usefulness of the proposed method, and especially it was shown that this method was powerful in the generation and detection of the $a_0$ mode.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.359-365
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• 1998

This study was conducted to isolate the protozoan parasite Babesia gibsoni by intraerythrocytic culture method of micoraerophilous stationary phase(MASP) and evaluate the possibility of application for the detection of B gibsoni in canine babesiosis. Also, indirect fluorescent antibody test(IFAT) and thick blood smear(giemsa stain), direct light microscopy (DLM), as control diagnostic tests, were conducted to compare diagnostic effects between MASP, IFAT and DLM. The results obtained from this study were summarized as follows. The protozoan parasite B gibsoni multiplied in 24-well polystyrene plate containing 1.2ml of canine red blood cell suspension in RPMI 1640 medium(pH 7.0) which is contained 20~40% normal canine serum(NCS) under the MASP condition of 5% $CO_2$ and 95% air at $37^{\circ}C$ incubator. Under the above MASP culturing system the percentage of parasitized erythrocytes(PPE) after incubation for 9 days reached the peak. The levels of PPE in MASP culture were shown more higher by exchanging the medium at 24 hour intervals. The parasite were purely isolated from MASP culture of canine red blood cells collected from dogs(pit bullterrier) infected with B gibsoni naturally. Among the total of 83 heads of pit bullterrier blood samples the positive rate was 32 heads(38.5%) in DLM, 45 heads(54.2%) in IFAT and 42 heads(50.6) in MASP culture. In negative cases of IFAT and DLM the isolation rates of B gibsoni by MASP culture were 16 heads(42.1%) of 38 heads and 16 heads(28.6%)% of 56 heads, respectively. From this study it was suggested that MASP culture method by RPMI 1640 medium was a reliable and useful diagnostic test for the diagnosis of B gibsoni infections in canine babesiosis.