• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.8-14
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• 2013

Steam turbine blades and discs of nuclear power plants are one of the most highly stressed areas of turbine rotor, and periodic inspection of the blade roots is essential for monitoring integrity and preventing turbine failure. Ultrasonic technique is applied for volumetric inspection of blade root. However, the complexity of blade root geometry imposes challenges to inspection of blades and discs. Recently, phased array ultrasonic inspection technology is being applied to numerous power generation inspection applications including turbine rotor. The phased array ultrasonic technique requires customized inspection wedges which are generally necessary to generate effectively higher incident angle. But the usage of this wedge can cause access limitation for the lower stage blades of turbine because of the wedge front length. Therefore, the shear wave phased array probe which can generate high inspection angle without wedge is essentially necessary. In this study, feasibility study is conducted for the shear wave phased array ultrasonic probe application to blade and disc inspection. As results, the experimental results show that the shear wave phased array probe can detect the flaw and measure its size with reliable accuracy. Therefore if this shear wave phased array probe is applied to field inspection of blade and disc, more reliable inspection is expected for turbine having access limitation.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.14-18
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• 2005

The ultrasonic handy scanner to be developed in this research is a nondestructive inspection equipment with various facility. The ultrasonic inspection is the technique area which apply range is increasing greatly with IT. The purpose of this research is development of a ultrasonic handy scan inspection device with the utility in a work spot. The ultrasonic handy scanner to be developed with portability in this research is able to carry out the spot inspection. It can contribute to the quality improvement, cost reduction and safety design.

• International Journal of Reliability and Applications
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• v.5 no.1
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• pp.25-36
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• 2004

Ultrasonic inspection system consist of the examination procedures, equipment, and operators. The reliability of nondestructive testing is influenced by the inspection environment, materials and types of defect. It is very difficult to estimate the reliability of NDT due to the various factors. Piping inspection round robin was conducted to quantify the capability of ultrasonic inspection during in-service. In this study, the models for predicting the ultrasonic NDE reliability by logistic model and linear regression model are discussed. The utility of the NDT reliability assessment is verified by the analysis of the data from round robin test with these models.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.34-42
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• 2007

Ultrasonic inspection method is more profitable than X-ray radiographic inspection in cost and effect of defect detection such as debond, damage, and it doesn't need special constructions. The method can also be a possible real time inspection with safety. This report explains 1)the experiment and analysis of ultrasonic property of solid propellant, 2)the inspection methods of propellant/liner debond by inside or outside inspection, and 3)the inspection methods of propellant microcrack by damage. From the results, it is possible to detect the defect of propellant/liner debond by inside or outside inspection. Futhermore, it can be possible to detect the propellant microcrack caused by damage using the ultrasonic attenuation.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.240-245
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• 2001

Ultrasonic inspection system is consisted of the operator, equipment and procedure. The reliability of results in ultrasonic inspection is affected by its ability. Furthermore, the reliability of nondestructive testing is influenced by the inspection environment, other materials and types of defect. Therefore, it is very difficult to estimate the reliability of NDT due to various factors. In this study, the probability of detection, used logistic probability model and Monte Carlo simulation, estimated the reliability of ultrasonic inspection. The utility of the NDT reliability assesment is verified by the analysis of the data from round robin test applied these models.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.2
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• pp.170-176
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• 1998

The team mixed PbO, $ZrO_2$, $TiO_2$, $Nb_2O_5$ and $MnCO_3$, to make $Pb[(Zr_{0.54}\;Ti_{0.46})\;Nb_{0.005}]O_3+4%MnCO_3$. The electroded PZT ceramics were poled by 3 kV/mm at $110^{\circ}C$ for 600 s. We assembled the 0.4mm thick PZT slices into ultrasonic transducers. Central frequency of the probe is 5 MHz, which is proper to the thickness gauge for steel pipes and for flaw detector. The probe can detect a disk shape defect of 1mm diameter at 15cm deep in steel block. The new probe's Fresnel zone that the ultrasonic beam do not broaden is 13mm. Over the Fresnel zone, the ultrasonic beam spreads. Half of the beam spread angle of the probe is $4.3^{\circ}-4.6^{\circ}$. This probe can be used for the ultrasonic transducers for non-destructive testing of steel bridges.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.82-88
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• 2003

The nondestructive internal quality evaluation of agricultural products has been strongly required from the needs for individual inspection. Recently, the ultrasonic wave has been considered as a solution fur this problem, and an ultrasonic system was constructed for the ultrasonic NDE of fruits and vegetables in our previous work. In this paper, the practical applicability of our ultrasonic system is tested fur the inspection of internal defects (central cavity) in Atlantic potato. Sound speed and RMS of transmitted ultrasonic wave signal were measured and classification algorithm using 2 dimensional stochastic analysis. was presented. Experimental results showed greater value of sound speed and RMS (root mean square) of transmitted signal in normal samples than in abnormal samples with cavity. Also a stochastic method to distinguish normal and abnormal showed fault detection rate less than 5%.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.143-148
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• 2019

Numerous pipe lines can be found on various plant-based industrial sites. These pipelines should be periodically checked for defects. Most of these pipelines are internally inaccessible and difficult to visually inspect. Therefore, the inspection is being carried out with the help of non-contact inspection equipment such as ultrasonic flaw detection equipment. The use of ultrasonic flaw detection equipment can raise time and efficiency issues. In order to solve this problem, we will study the basic technology necessary for the development of automated inspection system equipped with ultrasonic measuring equipment and verify the validity through the fabrication of the demonstration device.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.236-245
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• 2017

Purpose: There is no established inspection system for composite wind blade during the fabrication stage even though the blades are one of the most important part at wind generation system, but phased array ultrasonic testing method has been continuously studied about wind turbine blade with composite. When wind turbine blade with complex shape by phased array probe is inspected, it is necessary to study for system keeping constant pressure using pressure device. Methods: In this paper, we propose constant pressure device for inspecting wind turbine blade by phased array ultrasonic test method. Design of the device controller is based on Hunt-Crossley model. We evaluate reliability of phased array ultrasonic inspection result that applicated constant pressure device. Result: Defect indication is precise and its error is small when constant pressure mechanism based on Hunt-Crossley model was used. Conclusion: When inspection is progressed using constant pressure mechanism, the reliability of composite wind blade inspection can be improved.