• Journal of Ocean Engineering and Technology
• /
• v.1 no.1
• /
• pp.138-143
• /
• 1987

Friction welding has emerged as a reliable process for high-production commercial applications with significant economic and technical advantages. But nondestructive test in friction weld was not clearly developed. Therefore the experimental verification is necessary in order to understand the characteristcs of the pulse echo effects according to various change in welding conditions. This paper presents an attempt to determine the relationship between the varios welding conditions and the coefficients of reflection using the ultrasonic pulse echo method in dissibilar metals friction weld. The new approach of calculating the coefficients of reflection based on measured amplitudes of the echoes is applied in this paper. These coefficients provides a single quantitative measurement which involves both acoustic energy reflected at the welded interface as well as transmitted across the interface. As a result, it was known that the quantitave relationship between welding conditions and the coefficients of reflection using the ultrasonic pulse echo exists in dissimilar metals friction weld.

• Journal of ILASS-Korea
• /
• v.11 no.4
• /
• pp.234-243
• /
• 2006

Diesel autothermal reforming (ATR) is a chemical process to produce hydrogen for fuel cell applications. Several previous studies were carried out to identify technical issues in diesel reforming. It is hard to vaporize diesel due to its high boiling points. Liquid droplets of diesel result in inhomogeneous fuel mixing with other reactants such as $O_2\;and\;H_2O$, which leads to reduce the reforming efficiency and make undesired coke in reactor. To solve the fuel delivery issue, we applied an ultrasonic device as a fuel injection system. Ultrasonic injector (UI) remarkably enhanced the reforming efficiency. This paper will present the reforming results using UI. And we will discuss about atomization effects of diesel on autothermal reforming reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04b
• /
• pp.161-164
• /
• 2004

In this study, to develop the composition ceramics for the Ultrasonic vibrator, $Pb(Mn_{1/3}Nb_{2/3})O_3Pb(Zr.Ti)O_3$ system ceramics were manufactured as a function of PCN substitution. Its dielectric and piezoelectric characteristics were investigated. With increasing the amount of PCN substitution, electromechanical coupling factor(kp) were increased until 3mol% PCN and that after decreased. mechanical quality factor(Qm) showed the maxinum value at 2mol% PCN. Eletromechanical coupling factor, mechanical quality factor and dielectric constant were showed optimum value at PCN 2mol% as 0.58, 1630 and 1407, respectively for ultrasonic vibrator applications.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.607-608
• /
• 2006

This article deals the development of Agile and Intelligent Manufacturing System(AIM) for the assembly automation of a tiny ultrasonic actuator used in camera phones and PDAs. The system consists of multi-vision modules, end-effectors, a standard base frame, dispensers, jigs and modular manipulators. Subsystems are a vision system, a force control system and a virtual reality system. Experimental results show that the assembly process for the small components in the various IT applications can be realized by the AIM system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2005.05a
• /
• pp.258-263
• /
• 2005

Because of its high performance and accuracy, electron beam welding has an important role in industrial applications such as semi-conductor and LCD manufactures. Since its operation has been done in a vacuum room, it is very difficult to check out their weldability as well as the correct welding area of the specimen. In this study, a measurement system of the electron beam welding has been developed based on the 3-axis LVDT controlled table. In addition, the algorithm to tracking the welding line has been developed. Welded regions were measured by using an A-scan ultrasonic sensor only. Weldability of the aluminum specimen has been tested by newly developed measuring system. The results are compared with those by using an C-scan ultrasonic sensor, which show good agreements with each other.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.459-460
• /
• 2007

In this paper, we describe a development of ultrasonic nondestructive evaluation software to analyze steam generator of nuclear power plant. The developed software includes classical analysis method such as A, B, C and D-scan images. And it can analyze the size and the location of internal cracks using 2D image. To do such, we obtain raw data from specimens of real pipeline of power plants, and get the crack points using LPF and differential method from obtained ultrasonic 1-dimensional data. The results of applications showed that the developed software provided accurate images of cracks on various specimens.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.1
• /
• pp.24-33
• /
• 1994

The main applications of CFRP are sports, aerospace and general industrial uses including automobiles. As this application fields expands the opportunity of machining, but CFRP is difficult to cut because of delamination of the composites and the short tool life. In this paper, the machinability of multidirectional CFRP by means of ultrasonic vibration cutting, which has been verified experimentally investigated.The experimentally to be highly effective in view of cutting force and surface quality.

• Journal of the Korean Society for Railway
• /
• v.6 no.2
• /
• pp.81-86
• /
• 2003

This study proposes the neural network simulator for the integrity evaluation of weld zone in railway rails. For these purposes, the ultrasonic signals for defects(crack) of weld zone in frames are acquired in the type of time series data and echo strength. The detection of the natural defects in railway truck is performed using the characteristics of echodynamic pattern in ultrasonic signal. And then their applications evaluated feature extraction based on the time-frequency-attractor domain(peak to peak, rise time, rise slope, fall time, fall slope, pulse duration, power spectrum, and bandwidth) and attractor characteristics (fractal dimension and attractor quadrant) etc. The constructed neural network simulator agrees fairly well with the measured results of test block(defect location, beam propagation distance, echo strength, etc). The Proposed neural network simulator in this study can be used for the integrity evaluation of weld zone in railway rails.

• Analytical Science and Technology
• /
• v.19 no.6
• /
• pp.504-511
• /
• 2006

Polysilanes with organic substituents such as methyl and phenyl were synthesized by Wurtz dechlorination-condensation reactions using ultrasonic from organochlorosilanes. The yields were compared with the results of thermal dechlorination-condensation reactions. Properties such as thermogravimetric analysis and photoreactivity were investigated for the possibility of applications.

• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.437-443
• /
• 2024

The development and testing of inspection equipment is necessary for the safe deployment of advanced nuclear reactors. One proposed advanced reactor design is Westinghouse's lead-cooled fast reactor (LFR). In this paper, the process of achieving adequate wetting for an ultrasonic under-lead viewing system is discussed and results presented. Such a device would be used for inspection in the molten lead core during reactor outages. Wider tests into the wetting of various materials in molten lead at microscale were performed using electron microscopy. The possible mechanisms and kinetics for materials wetting in lead, particularly stainless steel and nickel, are proposed and discussed.