• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.348-353
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• 2004

This study is aimed for the implementation of ultrasonic method to assess the reliability of turbine bearings. A modified ultrasonic immersion technique was carried out in both laboratory experiment and field application. From the laboratory results, we confirmed that the condition of interface layer between the babbitt and base metal be monitored by the C-Scan. The C-scan image by the ultrasonic immersion test can be used successfully to observe the condition of interface layer. The testing with a focused transducer provides a promising approach for estimating the extent of the damaged region and observing the interface layer effectively. The difference of the ultrasonic reflection ratio between the bonding and debonding area at the interface layer is one of the key parameters for assessing the extent of the damaged area; additionally, the reflection amplitude exhibits a favorable correlation with the overall damage level. The technique developed in this study was applied to the inspection of the turbine bearings at several power plants in Korea whereby the applicability in the field can be ascertained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2167-2173
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• 2000

The HANARO (High-flux Advanced Neutron Application Reactor) has operated since 1995. The Cold Neutron(CN) hole was implanted in the reflector tank from the design stage. Before a vacuum chamber and a moderator cell for the cold neutron source are installed into the CN hole, it is necessary to measure the exact size of the inside diameter and thickness of the CN hole to prevent the interference problem. Due to inaccessibility and high radiation field in the CN hole, a mechanical measurement method is not permitted. The immersion ultrasonic technique is considered as the best method to measure the thickness and the diameter. The 4 axis manipulator of the 2 channel of a sensor module was fabricated. The transducer of 10 MHz results in 0.03 nun of resolution. The inside diameter and thickness for 550 points of the CN hole were measured using 2 channel ultrasonic sensors. The results showed that the thickness is in the range of 13-6.7 mm and inside diameter is in the range of o 156-165. These data will be a good reference in the design of a cold neutron source facility.

• Korean Journal of Food Science and Technology
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• v.17 no.5
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• pp.340-344
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• 1985

In this study, an effective method for purifying of crude agar was attempted, and at the same time, the effect of crude protein and ash contained in impurified agar on the gel strength of the agar were investigated. In order to reduce the content of protein of crude agar, the agar extract was treated with a protein precipitant such as tricholoroacetic acid(TCA) or perchloric acid(PCA), whereas washing with deionized water was applied to decrease the ash content of agar extract. Among the protein precipitants used in the experiment PCA reduced the crude proteins of crude agar most efficiently; addition of 0.01% PCA resulted in the reduction of crude protein content by 3%, and the gel strength of agar thereby increased from 220g/$cm^{2}$ to 402g/$cm^{2}$. High ash content of crude agar was removed by means of washing treatment and it decreased from 8.1% to 2.7%, leading to the gel strength of 530g/$cm^{2}4$.