• Journal of Biomedical Engineering Research
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• v.41 no.5
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• pp.195-202
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• 2020

Needle detection in ultrasound images is sometimes difficult due to obstruction of fat tissues. Accurate needle detection using continuous ultrasound (CUS) images is a vital stage of treatment planning for tissue biopsy and brachytherapy. The main goal of the study is classified into two categories. First, new detection model, i.e. D-Attention Unet, is developed by combining the context information of 3D medical data and CUS images. Second, the D-Attention Unet model was compared with other models to verify its usefulness for needle detection in continuous ultrasound images. The continuous needle images taken with ultrasonic waves were converted into still images for dataset to evaluate the performance of the D-Attention Unet. The dataset was used for training and testing. Based on the results, the proposed D-Attention Unet model showed the better performance than other 3 models (Unet, D-Unet and Attention Unet), with Dice Similarity Coefficient (DSC), Recall and Precision at 71.9%, 70.6% and 73.7%, respectively. In conclusion, the D-Attention Unet model provides accurate needle detection for US-guided biopsy or brachytherapy, facilitating the clinical workflow. Especially, this kind of research is enthusiastically being performed on how to add image processing techniques to learning techniques. Thus, the proposed method is applied in this manner, it will be more effective technique than before.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.637-646
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• 2007

An UET (ultrasound excited thermography) has been used for several years for a remote non-destructive testing in the automotive and aircraft industry. It provides a thermo sonic image for a defect detection. A thermograhy is based On a propagation and a reflection of a thermal wave, which is launched from the surface into the inspected sample by an absorption of a modulated radiation. For an energy deposition to a sample, the UET uses an ultrasound excited vibration energy as an internal heat source. In this paper the applicability of the UET for a realtime defect detection is described. Measurements were performed on two kinds of pipes made from a copper and a CFRP material. In the interior of the CFRP pipe (70mm diameter), a groove (width - 6mm, depth - 2.7mm, and length - 70mm) was engraved by a milling. In the case of the copper pipe, a defect was made with a groove (width - 2mm, depth - 1mm, and length - 110 mm) by the same method. An ultrasonic vibration energy of a pulsed type is injected into the exterior side of the pipe. A hot spot, which is a small area around the defect was considerably heated up when compared to the other intact areas, was observed. A test On a damaged copper pipe produced a thermo sonic image, which was an excellent image contrast when compared to a CFRP pipe. Test on a CFRP pipe with a subsurface defect revealed a thermo sonic image at the groove position which was a relatively weak contrast.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.98-104
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• 2018

Nondestructive strength Equations are commonly used to determine the strength of concrete. However, the application of the existing equations may include many errors because this method is proposed on the basis of limited experimental parameters while actual bridges have various parameters such as conditions of concrete mixtures, properties of concrete strength, etc. Also, the error among the existing equations causes the confusion when engineers select the proper estimation equation for the concerned bridge. In this study, a series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges, based on the test results of the in-depth inspection, and the estimated strengths by means of the nondestructive strength equations are analyzed and compared with results of the core specimen strengths. According to results of analyses, the nondestructive strength equation proposed by CNDT Committee of Architectural Institute of Japan had high relationship with core strength. However, the strengths predicted by this equation, are underestimated when concrete's strengths are over 30 MPa, otherwise, they are overestimated. Also in this paper, based on the relationship between the estimated nondestructive concrete strengths and the core specimen strengths the modified strength equation through simple correlation analysis is proposed.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.90-95
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• 2013

Pipe inside clad welding is mainly used to the flow pipe of sub-sea or chemical plant. For the inside clad welding to the medium pipe with the diameter of about 12", TIG welding is frequently applied with filler metal. In this case, the clad welding has the very broad weld area over $10m^2$. And, the non-destructive test (NDT) such as ultrasonic test (UT) or radiographic testing (RT) should be conducted on the broad weld area, and it costs very high due to the time-consuming work. Therefore, the present study investigated the variation of arc voltage to develop the in-line quality monitoring system for the pipe inside TIG cladding. The 4 experimental parameters (current, arc length, wire feed position, and shield gas flow rate) varied to observe the change of arc voltage and to establish the model for the monitoring. The arc voltage was decreased when the wire was fed to the backward eccentric position(over 2mm), and the shield gas flow rate was insufficient under 10L/min. In the case of the backward eccentric position over 2mm, the bead appearance was not good and the dilution ratio was increased due to deep penetration. When the shield gas flow rate was lower than 10L/min, the bead surface was oxidized.

• Advances in nano research
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• v.14 no.5
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• pp.435-442
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• 2023

Sports activities, including playing tennis, are popular with many people. As this industry has become more professionalized, investors and those involved in sports are sure to pay attention to any tool that improves athletes' performance Tennis requires perfect coordination between hands, eyes, and the whole body. Consequently, to perform long-term sports, athletes must have enough muscle strength, flexibility, and endurance. Tennis rackets with new frames were manufactured because tennis players' performance depends on their rackets. These rackets are distinguished by their lighter weight. Composite rackets are available in many types, most of which are made from the latest composite materials. During physical exercise with a tennis racket, nanocomposite materials have a significant effect on reducing injuries. Materials as strong as graphite and thermoplastic can be used to produce these composites that include both fiber and filament. Polyamide is a thermoplastic typically used in composites as a matrix. In today's manufacturing process, materials are made more flexible, structurally more vital, and lighter. This paper discusses the production, testing, and structural analysis of a new polyamide/Multi-walled carbon nanotube nanocomposite. This polyamide can be a suitable substitute for other composite materials in the tennis racket frame. By compression polymerization, polyamide was synthesized. The functionalization of Multi-walled carbon nanotube (MWCNT) was achieved using sulfuric acid and nitric acid, followed by ultrasonic preparation of nanocomposite materials with weight percentages of 5, 10, and 15. Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) confirmed a synthesized nanocomposite structure. Nanocomposites were tested for thermal resistance using the simultaneous thermal analysis (DTA-TG) method. scanning electron microscopy (SEM) analysis was used to determine pores' size, structure, and surface area. An X-ray diffraction analysis (XRD) analysis was used to determine their amorphous nature.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.1
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• pp.3-12
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• 2006

The purpose of this study is to describe the Non-Destructive Testing(NDT) of the rockbolt and investigate the applicability of the NDT methods to estimate the integrity of the rockbolt. To examine the rockbolt integrity including rockbolt itself and grouting material, two methods are adopted: numerical and experimental methods. In the numerical method, the numerical code DISPERSE is used to analyze the dispersion of the rockbolt. The dispersion curve shows the effects of the thickness and stiffness of grouted materials on the embedded rockbolt. Therefore, the optimal frequency for the integrity test of the rockbolt is obtained: 20~120kHz in L(1,0) mode. In the experimental methods, destructive and non-destructive tests are carried out in a laboratory. In the non-destructive test, the low frequency mode generated by an impact and t he high frequency mode generated by an ultrasonic transducer seem to characterize the rockbolt condition readily. The experimental results show that the guided waves attenuate more significantly when the stiffness of the grouted material increases and/or the zone of the defect increases. Meanwhile, the ultimate capacity of rockbolt was evaluated through the pull-out tests and is compared to the NDT results. This study demonstrates that the NDT is a valuable tool for the rockbolt integrity evaluation.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.384-389
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• 2004

As the increase of the operation year of nuclear power plants, the probabilities of the degradation of the major facilities and materials in the nuclear power plants are increased. The integrity of those facilities shall be monitored and verified by the non-destructive examination methods with the regulation codes, so called inservice inspection(ISI). The ISI of Yonggwang unit 6 was performed in four different parts, 1) non-destructive examinations for the components, piping weldments and structures, 2) automated ultrasonic examinations for pressure vessels, 3) visual examinations for the interior structures of the reactor, 4) eddy current examinations for the steam generator tubes. As the results, there was no severe indication and all detected indications were evaluated as non-relavent. Especially for the examinations of the piping weldments, PD(Performance Demonstration) was applied as a W examination method defined in the 1995 edition of ASME Code Sec. XI. The implementation of the PD for the piping weld results in an improvement of the reliability of the UT examinations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.295-302
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• 2011

The setting time which is the important element for the determination of slip-up speed of Slip-Form system is the hardening time of early-age concrete when the in place concrete has minimum compressive strength before the concrete appears out of Slip-Form system. But it is very difficult to predict the setting time because it depends on not only the composition ratio of concrete but also various conditions of construction fields. Thus, the technique to estimate accurately and continuously the hardening time of early-age in place concrete during operating Slip-Form system is necessary to guarantee the safety of Slip-Form system and the maintenance of the shape of concrete. Ultrasonic wave-based nondestructive testing methods have the advantages which are accurate and continuous in estimating concrete compressive strength. Of such methods, the method using surface wave which propagates along the surface of material is effective for thick member such as a pylon. Thus, in this paper a study on the determination of slip-up speed for Slip-Form system using surface wave velocity is performed. The relation between the slip-up speed of Slip-Form system and the setting time is formulated, and the surface wave velocity is estimated from continuous wavelet transform of the numerical results for surface wave propagation. Finally, the accuracy of this method according to the distance between the wave source and receivers and the relation between the estimated surface wave velocity and the elastic modulus are investigated.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.177-185
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• 2014

Purpose: This study is designed to investigate the various impacts of different types of scaler tips such as cooper alloy base tip and the others on the surface roughness of teeth and implant by the method which is currently in clinical use. Materials and methods: Four different types of disc shaped porcelain, titanium, zirconia, and Type III gold alloy dental materials sized 15 mm diameter, 1.5 mm thickness were used for the experiment. Plastic hand curette (Group PS), cooper alloy new tip (Group IS), and stainless steel tip (Group SS) were used as testing appliances. A total of 64 specimens were used for this study; Four specimens for each material and appliance group. Surface roughness was formed with 15 degree angle in ultrasonic scaler tip and with 45 degree angle in hand curette of instrument tip and the specimen surface with 5 mm long, one horizontal-reciprocating motion per second for 30 seconds by 40 g force. To survey the surface roughness of each specimen, a field emission scanning electron microscope, an atomic force microscope, and a surface profiler were used. (Ra, ${\mu}m$). Results: According to SEM, most increased surface roughness was observed in SS group while IS groups had minimal roughness change. Measurement by atomic force microscope presented that the surface roughness of SS group was significantly greater than those of PS, IS and control groups in the type III gold alloy group (P<.05). IS group showed lesser surface roughness changes compared to SS group in porcelain and gold alloy group (P<.05). According to surface profiler, surface roughness of SS group showed greater than those of PS, IS and control groups and IS group showed lesser than those of SS group in all specimen groups. Type III gold alloy group had large changes on surface roughness than those of porcelain, titanium, zirconia (P<.05). Conclusion: The result of this study showed that newly developed copper alloy scaler tip can cause minimal roughness impacts on the surface of implant and dental materials; therefore this may be a useful alternative for prophylaxis of implant and restored teeth.