• Journal of the Korean Society of Marine Environment & Safety
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• v.6 no.1
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• pp.57-67
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• 2000

All crude oil carries a little of water, sand, and mineral sediment molecules tightly bounded with hydrocarbons. The result is the gradual precipitation of these heavier elements into thick, granular petroleum by products known as crude oil sludge. The oily sludges in ship tanks and in storage facilities have to be treated efficiently in order to keep the security and the capacity of storage facilities, to protect a serious environmental pollution, and to retrieve lost resource. The oily sludge treatment system should be designed to satisfy requirements mentioned in safe work condition. As a basic study, in this paper, an oily sludge treatment system by ultrasonic waves was proposed. Then, the features of ultrasonic energy and recovery of sludge with ultrasonic waves are investigated by experiments. As results, we found that ultrasonic waves are a new energy to flow oil sludge environment-friendly in safe work condition. In addition, it was shown that ultrasonic energy is more efficient than thermal energy in treating oil sludge, and that the volume of wastes for disposal is reduced remarkably.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.214-220
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• 2015

Since resources of fossil fuels are limited, development of alternative energies is emphasized and research on new-regenerative energy is actively in progress worldwide. In present research, physical and chemical characteristics of mixed fuel are analyzed in detail for the different mixture rate of conventional and bio-diesel and ultrasonic irradiation time. Experimental setup consists of ultrasonic generator, vibrator, horn, and reflector. Various physical and chemical characteristics of fuel are investigated for volumetric mixture rate of bio-diesel from 0 to 100%. As results, viscosity and surface tension is increased as mixture rate of bio-diesel is increased. Also, molecular splits and reunions are increased and decreased repeatedly after some period of time as ultrasonic energy irradiation time is increased. As conclusion of experiments, Olefin rate, Branch index, and Aromatic rate are influenced by ultrasonic irradiation time.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1846-1857
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• 2021

Ultrasonic nondestructive testing is important for monitoring the structural integrity of dissimilar metal welds (DMWs) in pressure vessels and piping in nuclear power plants. However, there is a low probability of crack detection via inspection of DMWs using ultrasonic waves because the grain structures (grain orientations) of the weld area cause distortion and splitting of ultrasonic beams propagating in anisotropic media. To overcome this issue, the grain orientation should be known, and a precise ultrasonic wave simulation technique in anisotropic media is required to model the distortion and splitting of the waves accurately. In this study, a method for nondestructive prediction of the DMW grain orientations is presented for accurate simulation of ultrasonic wave propagation behavior in the weld area. The ultrasonic wave propagation behavior in anisotropic media is simulated via finite-element analysis when ultrasonic waves propagate in a transversely isotropic material. In addition, a methodology to predict the DMW grain orientation is proposed that employs a simulation technique for ultrasonic wave propagation behavior calculation and an optimization technique. The simulated ultrasonic wave behaviors with the grain orientations predicted via the proposed method demonstrate its usefulness. Moreover, the method can be used to determine the focal law in DMWs.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.64-71
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• 2003

In order to analyze the effect of the chemical structure and the cetane number of reformed diesel fuels by ultrasonic energy irradiation, proton nuclear magnetic resonance spectrometer$(^1H-NMR)$ was used. From the study, following conclusive remarks can be made. 1) Branch Index(BI), aromatics percentages, and alpha methyl radical$(H_{\alpha})$ of the reformed diesel fuels by ultrasonic energy irradiation decreased more than the conventional ones. 2) All the cetane numbers which were calculated from carbon type structure and hydrogen type distribution of the reformed diesel fuels increased more than the conventional ones. 3) It is more reasonable to predict cetane number equation from carbon type structure than from hydrogen type distribution. 4) BI, aromatics percentages, and $H_{\alpha}$ on both for conventional fuel and reformed diesel fuels by ultrasonic energy irradiation are inversely proportional to cetane number fur these fuels.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.29-34
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• 2004

To investigate characteristics and micro-explosion of single-droplets of emulsified fuel, water is mixed with diesel oil by using ultrasonic energy fuel feeding system. The fuel characteristics is analysed through H-NMR spectrum and micro-explosion phenomena of the emulsified fuel is also investigated. The life times of droplets of conventional diesel fuel, ultrasonic energy added diesel fuel and emulsified fuel we obtained additionally. According to this study, the micro-explosion phenomena of single-droplets happen in atmospheric pressure condition, a curve form of emulsified fuel's life tim is different from diesel fuel's one and the change of chemical structures is a cause of ultrasonic-energy-added diesel fuel effect.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.1-7
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• 2004

This experiment was undertaken to investigate the atomization characteristics of the low viscosity biodiesel blended fuel and ultrasonic energy added one. Test fuels were conventional diesel fuel and biodiesel fuel. We compared to the characteristics of viscosity and surface tension, SMD between low viscosity biodiesel blended fuel and ultrasonic energy added one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension was measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy added situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than that of the conventional situation.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.369-377
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• 2003

Since Zr-2.5Nb pressure tubes have a high risk for the formation of blisters during their operation in pressurized heavy water reactors, there has been a strong incentive to develop a method for the non-destructive detection of blisters grown on the tube surfaces. However, because there is little mismatch in acoustic impedance between the hydride blisters and zirconium matrix, it is not easy to distinguish the boundary between the blister and zirconium matrix with conventional ultrasonic methods. This study has focused on the development of a special ultrasonic method, so called ultrasonic velocity ratio method for a reliable detection of blisters formed on Zr-2.5Nb pressure tubes. Hydride blisters were grown on the outer surface of the Zr-2.5Nb pressure tube using a cold finger attached to a steady state thermal diffusion equipment. To maximize a difference in the ultrasonic velocity in hydride blisters and the zirconium matrix, the ultrasonic velocity ratio of longitudinal wave to shear wave, $V_L/V_S$, has been determined based on the flight time of the longitudinal echo and reflected shear echo from the outer surface of the tubes. The feasibility of the ultrasonic velocity ratio method is confirmed by comparing the contour plots reproduced by this method with those of the blisters grown on the Zr-2.5Nb pressure tubes.

• Journal of ILASS-Korea
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• v.8 no.4
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• pp.1-8
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• 2003

The objective of this study is to investigate experimentally atomization characteristics for differently made an ultrasonic twin-fluid nozzle. A spray system, an ultrasonic system, and three different type(Nozzle type, Tube type, Conventional type)are made and tested by applied with ultrasonic energy. In this investigation, the measurement and calculation of spray droplet are to analyze the effects of ultrasonic energy on the agricultural atomization system. Through the measurement of suray angle, spray column using, high speed camera and PDA, it is found that nozzle type is highest efficiency than that of tube type and conventional type. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 9% respectively and spray angle was wide spray.

• Nuclear Engineering and Technology
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• v.36 no.1
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• pp.12-23
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• 2004

In the present study a new measurement technique has been developed, which uses an ultrasonic transmission signal in order to identify the vertical two phase flow pattern. The ultrasonic measurement system developed in the present study not only provides the information required for the identification of vertical two phase flow patterns but also makes real time identification possible. Various vertical two phase flow patterns such as bubbly, slug, churn, annular flow etc. have been accurately identified with the present ultrasonic measurement system under atmospheric condition. In addition, the present test apparatus can practically simulate the ultrasonic propagation characteristics under high temperature and high pressure systems. Therefore, it is expected that the present ultrasonic flow pattern identification technique could be applicable to the vertical two phase flow systems under high temperature and high pressure conditions.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.751-755
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• 1999

Effect of ultrasonic-wave irradiation on the Mn-Zn ferrite powder suspension prepared by solid-state reaction and alcoholic dehydration methods was investigated. Size distribution and morphology of the powders prepared at different temperature were examined as a function of irradiation time. It was observed that the powders were reduced in size by ultrasonic energy through distinct routes.