• Journal of Korea Foundry Society
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• v.21 no.3
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• pp.163-178
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• 2001

The squeeze infiltration process is potentially of considerable industrial importance. The performance enhancements resulting from incorporation of short alumina fiber into aluminum are well documented. These are particularly significant for certain automobile components. Aluminum matrix composite automotive parts, such as diesel engine pistons or engine blocks are produced using squeeze casting apparatus or pressure die-casting apparatus. But the solidification process gets complicated with manufacturing parameters and the factors for porosity formation have not fully understood yet. In this study the formation of porosity during squeeze infiltration has been studied experimentally to achieve an improved understanding of the squeeze infiltration process for manufacture of short-fiber-reinforced components, particularly the mechanism of porosity formation. Al-based MMCs produced under a range of conditions were examined metallographically and the porosity characterised;a kind of matrix, an initial temperature of melt, and a volume fraction of reinforcement. The densimetry and the microscopic image analysis were done to measure the amount of porosity. A correlation between manufacturing parameters and defects was investigated through these.

• Transactions on Electrical and Electronic Materials
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• v.13 no.4
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• pp.212-214
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• 2012

Both the electrically positive and negative particles in a cell of quick response-liquid powder display (QR-LPD) are surrounded by conductive electrodes on the upper and lower substrate and the dielectric materials of the barrier ribs. Particles in a cell are attached to or detached from the other materials by image force, electric field, Coulomb's force, and Van der Waals' force. Through these forces, the moving particles form an image but induce clumping phenomena. Particles having a large kinetic energy by a large q/m value crash into the opposite electrode with high speed at a large driving voltage and quickly lose electrically charged material. As a result, these particles are clumped and degrade panel performance. The clumped particles in a cell are observed by microscopic photographs and ascertained by a response time. When the bias voltage is increased to 0.68-0.76 $V/{\mu}m$, particle clumping occurs abruptly and the response time increases sharply. This particle clumping is similarly observed after the number of driving times at the driving voltage (0.42-0.64 $V/{\mu}m$).

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.329-334
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• 2006

We have reconstructed 3-dimensional images by using the digital holographic microscope and the Mask-cut phase unwrapping algorithm. Off-axis holograms recorded with a magnified image of the microscopic object lens and reference beam are numerically reconstructed in amplitude and phase image by the Fresnel diffraction approximation. We have simultaneously reconstructed 2-dimensional and 3-dimensional images of the sub-micrometer objects.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.71-77
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• 2010

Although the problems of defects and nonmetallic inclusion in metal fatigue are very complicated, it is particularly important to view these problems from the perspective that defects and inclusions are virtually equivalent to small cracks. This concept will help one to understand various fatigue phenomena caused by Ductile Cast Iron. For different ferrite-pearlite matrix structure, containing more than 90% spheroidal ratio of graphite, GCD 45-3, GCD 50, GCD 60 series and 70%, 80%, 90% spheroidal ratio of graphite, GCD 40, GCD 45-1, GCD 45-2 series, this paper has carried out image analyzer, estimated maximum and mean size of graphite, investigated correlation. It was concluded as follows. (1) A good quality of Ductile cast iron using in this experiment, the graphite was separated well. The effect of the interaction by graphite was verified by microscopic observation and by fracture mechanics investigation in surface, interior of the specimen. (2)${\sqrt{area}}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of ${\sqrt{area}}$ may be used as a guide line for the control of inclusion size in the steel making processes.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1275-1280
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• 2014

In this study, the performance of a real-time micro telescopic monitoring system is evaluated, in which an artificial neural network is adopted for the diagnoses of vibratory bodies, such as solid piping system or machinery. The structural vibration was measured by a non-contact remote sensing method, in which images of a high-speed high-definition camera were used. The structural vibration data that can be obtained by the PIV (particle image velocimetry) technique were used for training the neural network. The structures of the neural network are dynamically changed and their performances are evaluated for the constructed diagnosis system. Optimized structures of the neural network are proposed for real-time diagnosis for the piping system. It was experimentally verified that the performances of the neural network used for real-time monitoring are influenced by the types of the vibration data, such as minimum, maximum and average values of the vibration data. It concludes that the time-mean values are most appropriate for monitoring the piping system.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.154-160
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• 1997

By their rapid and periodic actions, the cilia of the human respiratory tract play an important role in clearing inhaled noxious particles. Based on the automated image-processing technique, we studied ciliary beat frequency (CBF) objectively and quantitatively. Microscopic ciliary images were transformed into digitized gray ones through an image-grabber, and from these we extracted signals or CBF. By means of a FFT, maximum peak frequencies were detected as CBFs in each partitioned block or the entire digitized field. With these CBFs, we composed distribution maps visualiy showing the spatial distribution of CBFs. Through distribution maps of CBF, the whole aspects of CBF changes or cells and the difference of CBF of neighboring cells can be easily measured and detected. Histogram statistics calculated from the user-defined polygonal window can show the local dominant frequency presumed to be the CBF of a cell or a crust the region includes.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.542-557
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• 2019

The behavior of rock mass is influenced by its microscopic feature of internal structure generating from forming and metamorphic process. This study investigated a new methodology for characterization of rock based on the X-ray CT (computed tomography) images reflecting the spatial distribution characteristics of internal constituent materials. The X-ray image based analysis is capable of quantification of heterogeneity and anisotropy of rock fabric, size distribution and shape parameter analysis of rock mineral grains, fluid flow simulation based on pore geometry image and roughness evaluation of unexposed joint surface which are hardly acquired by conventional rock testing methods.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.12-18
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• 2004

Transient natures of diesel sprays are often characterized with spray visualization, since it is a non-intrusive and straightforward technique to be applied. However, as injection pressure is increased higher than a thousand bar in a modern direct injection diesel engine, very fine temporal and spatial resolutions in the spray visualization are required while sprays become optically denser. Discussed in this paper are macroscopic and microscopic spray visualization techniques and an example of image processing process for efficient and consistent measurement of spray parameters. The injection rate measurement method based on hydraulic pulse principle was suggested as a way of estimating injection velocity for transient diesel sprays. The spray visualization and injection rate measurement techniques were applied to analyze transient diesel sprays from a common-rail injection system and found to be practically effective.

• Journal of Magnetics
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• v.8 no.1
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• pp.13-17
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• 2003

The longitudinal magnetooptical Kerr effect was used to analyse magnetic domains in soft magnetic ${(Fe_{97}A1_3)}_{85}N_{15}$/$Al_{2}O_{3}$ multilayers in order to get microscopic understanding of interlayer exchange coupling. The measuring system consists of a Kerr microscope, a CCIR camera (with an 8-bit framegrabber), 16 bit digital camera and computer system for real-time image processing and to control external magnetic field and cameras. The strength of ferromagnetic (EM) coupling as a function of the spacer thickness of $Al_2O_3$ was investigated. It was found that strong FM-coupling, strong uniaxial anisotropy and coherent rotation of the magnetization have been observed for the spacer thickness in the range of 0.2 nm $\leq$ t $\leq$ 1 m, however, weak FM-coupling, patch domains and $360^{\circ}$-walls occur for the spacer thickness of t = 2.5 nm. At a spacer thickness of t $\geq$ 5 nm transition takes place from weak FM-coupling to the decoupled state where complex interlayer interactions and different types of the domain walls were observed.

• Computers and Concrete
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• v.5 no.2
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• pp.101-116
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• 2008

The microscopic determination of air void characteristics in hardened concrete, defined in EN 480-11 as the linear-traverse method, is an extremely time-consuming and tedious task. Over past decades, several researchers have proposed relatively expensive mechanical automated systems which could replace the human operator in this procedure. Recently, the appearance of new high-resolution flatbed scanners has made it possible for the procedure to be automated in a fully-computerized and thus cost-effective way. The results of our work indicate the high sensitivity of such image analysis automated systems firstly to the quality of sample surface preparation, secondly to the selection of the air void threshold value, and finally to the selection of the probe system. However, it can be concluded that in case of careful validation and the use of the approach which is proposed in the paper, such automated systems can give very good estimate of the air void system parameters, defined in EN 480-11. The amount of time saved by using such a procedure is immense, and there is also the possibility of using alternative stereological methods to assess other, perhaps also important, characteristics of air void system in hardened concrete.