• Proceedings of the KOSOMBE Conference
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• v.1990 no.11
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• pp.5-10
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• 1990

The object detection capabilities of ultrasonic imaging systems are limited by the ability of the detection process to distinguish the resolved object signals from backscattered speckle noise. It has been shown that the phase component of the Fourier transform of the speckle noise is random. Based on this property. we propose a new algorithm for distinguishing between speckle and specular targets. The proposed algorithm is implemented by taking the Fourier transform of the received signal, low-pass filtering the phase, and taking the inverse Fourier transform of the filtered phase to enhance specular reflectors and reduce speckle in the image. Simulations and experiments using phantoms confirm the algorithm yielding significant reduction of speckle noise.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.119-122
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• 1997

In this paper, we represented the variation of heart cavity area in the space domain by 3-d rendering. We arranged the 2-d sequence of ultrasonic image acquired in the time domain as volumetric data, and extracted heart cavity region from 3-d data. For the segmentation of 3-d volume data, we extracted the cavity region using the method of expanding the cavity region that is same statistical property. By shading which is using light and object normal vector, we visualized the volume data on image plane.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.658-662
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• 2003

In this study, we have tried to find the optimized design variables of the matching layer which is important part of thickness mode ultrasonic transducer and finally reach the conclusion that the electrical property of piezo-element must be under consideration when the optimized acoustic impedance is estimated. Proper expression of the effective impedance of front load at free resonant frequency(: $Z_{f}$ $^{(0)}$ /) has been induced by introducing the principle of binomial multilayer transformer and gradient based numerical method is utilized to find the most acceptable value of $Z_{ f}$/$^{(0)}$ . Optimized point of acoustic impedance can be calculated directly from $Z_{f}$ $^{(0)}$ using some simple formula which we propose. We also verify our result by both numerical and experimental method and get a good enhancement especially it concern to the bandwidth of ultrasonic transducer.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.62-67
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• 2010

The objective of this experimental study is to verify atomization characteristics of emulsified fuel. The emulsified fuel made of adding the ultrasonic energy is analyzed with atomization characteristics and chemicophysics. As water contents within emulsified fuel and needle angle increase, SMD, viscosity and surface tension were analyzed. By measuring the distribution percentage of hydrogen volume by $^1H$-NMR spectrum, the proportion of aromatics and paraffins is analyzed and compared each other. The results of study is as follows. First, as water contents within emulsified fuel and needle angle of nozzle increases, SMD increases. Second, for the distribution percentage of hydrogen volume, the distribution percentage of aromatics is about 10% and the rest portion is paraffins.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.78-79
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• 2015

For estimating compressive strength of concrete, non-destructive test has conducted generally. It used experimental equation to calculate compressive strength from construction. This study investigated experiment to apply non-destructive test, based on fresh property, compressive strength and ultrasonic pulse velocity of high performance concrete. And it conducted to compare various proposed equation.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.293-298
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• 2009

The ultrasonic atomic force microscope(UAFM) has been developed in order to enhance the characterization technology for nano-scale surface combining ultrasonic property to atomic force microscope. This UAFM technique enables elasticity imaging due to the physical properties on the heterogeneous surface in addition to the novel topography of surface height in the nano-surface layer. In this study, the prototype UAFM system was constructed and applied to several materials, silicon deposited wafer, spherodized cold heading steel, and carbon fiber reinforced plastic specimen. Clear elastic contrast was successfully obtained using this developed prototype UAFM.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.632-636
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• 1993

Gel strength of fish protein at various processing conditions such as heating temperature, heating time and salt content was determined by using compressive stress and residual delay time of ultrasonic wave. The compressive stress, interpreted as indicating the relative gel strength, was increased with increasing the heating temperature and heating time, and with decreasing the salt content, while the delay time of ultrasonic wave reduced, indicating that the gel strength and the delay time are inverse proportion. The result of the multiple regression analysis with factorial design showed that the model equation consisted with delay time and processing condition variables gave the good prediction of the gel compressive stress which was coincided with compressive stress measured.

• Journal of the Korean Society of Marine Environment & Safety
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• v.9 no.1
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• pp.89-94
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• 2003

As ship's fuel oil recently becomes viscous and the amount of sludge increases, many researches and studies are underway to process the sludge onboard the ship and to recycle it as a fuel for ship's boiler. Of many researches, especially ultrasonic emulsifier to break the particle of sludge into fine pieces is recognized as a most possible recycling device. In this regards, the author investigates the property change of sludge's temperature and pressure at the early stage of the study of ultrasonic emulsifier. This study can be used as a useful dora to determine the proper temperature and pressure to inject the processed sludge in the boiler injector and the results can also be comparable dora with the experimental data by ultrasonic emulsifier. In addition, the results will be a fundamental data to study the filtering efficiency of the sludge particle broken by temperature and pressure. It is expected that this study ultimately play a role to prevent marine oil pollution as the sludge is recycled onboard the ship and used as a fuel for boiler.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.759-763
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• 2015

The laser machining process has been proposed as an advanced process for the selective fabrication of electrodes without a mask. In this study, we adapt laser machining to metals that have different thermal properties. Based on the results, the metals exhibit a different surface morphology, heat-affected zone (HAZ), and a recast layer around the machined surface according to their thermal conductivity, boiling point, and thermal diffusivity. Then, we apply ultrasonic-assisted laser machining to remove the recast layer. The ultrasonic-assisted laser machining exhibits a better surface quality in metals with higher diffusivity than those having lower diffusivity.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.2
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• pp.118-128
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• 1999

There are many ultrasonic measurement methods that are used in nondestructive testing applications. Some typical applications include material property determination, microstructural characterization. and flaw detection. Ultrasonic parameters such as velocity and attenuation are most commonly required in these applications. The accuracy and repeatability of testing results are dependent on both the hardware used to generate and receive the ultrasonic waves and on the analysis software for calculating these parameters. In this study, five analysis algorithms were implemented on a computer for measuring wave speed in a pulse echo. immersion testing configuration. In velocity measurements comparisons were made between the overlap. cross-correlation. Fourier transform. Hilbert transform, wavelet transform algorithms. Velocity measurement was applied to an isotropic steel sample using the five analysis algorithms. Frequency-dependent phase/group velocity and attenuation were also measured using the Fourier transform and wavelet transform algorithms on a composite laminate containing voids.