• 한국연소학회지
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• 제4권1호
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• pp.85-93
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• 1999

Experimental study on a porous ceramic liquid fuel combustor is performed. Compact burner with low pollutant emission and high combustion efficiency is realized through the use of porous ceramic materials of high porosities. The use of porous ceramic materials in burner material results in rapid vaporization of liquid fuel and enhancement in mixing process, and thus nearly premixed combustion of liquid fuel is achieved instead of diffusion and partially premixed combustion method, which is often used and apt to produce high pollutant emissions such as CO, NOx and soot. With this enhanced vaporization and premixing method of liquid fuel vapor and air, it is found that enhanced combustion process with intense radiation output and better emission characteristics in NOx, CO and soot emission, compared to other conventional liquid fuel burning method, are possible.

• 한국해양공학회지
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• 제23권6호
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• pp.23-31
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• 2009

The interaction of incident monochromatic waves with a bottom-mounted vertical porous circular cylinder is investigated using the framework of the three-dimensional linear potential theory. The porosity of the circular cylinder is uniform vertically but varies in the circumferential direction. By adjusting the porosities of the circular cylinder, both the wave blocking performance of a porous semi-circular breakwater and the wave responses inside a circular harbor with an entrance are applied as calculation examples. It is found that the reflected waves, wave run-up, and wave forces are significantly reduced due to wall porosity, which are positive factors for a breakwater, and the amplification factor of a circular harbor at resonant frequencies is greatly reduced by a porous sidewall.

• Transactions on Electrical and Electronic Materials
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• 제15권6호
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• pp.305-308
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• 2014

Organosilyl-modified and star-shaped poly (${\varepsilon}$-caprolactone) (m-PCL) was prepared, and added to polymethylsilsesquioxane (PMSSQ), to make composites. The end groups of m-PCL are chemically similar to PMSSQ, and m-PCL mixed well with PMSSQ in the composite. Porous PMSSQ film was made by further calcination of the composite film at elevated temperature. m-PCL-templated PMSSQ and the as-prepared porous PMSSQ were structurally, optically, and thermally characterized in thin films. The chemical binding of m-PCL and PMSSQ effectively suppressed the phase separation of PMSSQ and m-PCL during the curing process. After calcination at elevated temperature, there remained many pores in the PMSSQ matrix. The refractive indices of the resulting porous PMSSQ thin films decreased with increase of the film porosities, depending on the initial m-PCL loadings.

• 자원환경지질
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• 제27권3호
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• pp.289-294
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• 1994

This paper describes an effective utilization method of well logging data and boring cores for understanding the geology of Keoje-do area. Six holes were drilled in 1988-1989, and all rock cores were recovered. Nevertheless, seven kinds of logs were carried out in each borehole. The geologic situations of the drilling sites are accurately evaluated from a comparison between core descriptions and well logging data. Porosities and clay contents of sedimentary rocks can be calculated using the data of density and gamma-ray logs. Fractured zones are easily detected from the change in inside diameter of borehole by caliper log. Sonic, density and gamma-ray logging data clearly indicate alternated and dyke zones; the former can be detceted from an acoustic wave attenuation and a decline of compaction by sonic and density logs, the latter can be detected from the amount of potassium contents of bed rock and dyke by gamma-ray log.

• Structural Engineering and Mechanics
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• 제64권6권
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• pp.683-693
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• 2017

According to a generalized nonlocal strain gradient theory (NSGT), dynamic modeling and free vibrational analysis of nanoporous inhomogeneous nanoplates is presented. The present model incorporates two scale coefficients to examine vibration behavior of nanoplates much accurately. Porosity-dependent material properties of the nanoplate are defined via a modified power-law function. The nanoplate is resting on a viscoelastic substrate and is subjected to hygro-thermal environment and in-plane linearly varying mechanical loads. The governing equations and related classical and non-classical boundary conditions are derived based on Hamilton's principle. These equations are solved for hinged nanoplates via Galerkin's method. Obtained results show the importance of hygro-thermal loading, viscoelastic medium, in-plane bending load, gradient index, nonlocal parameter, strain gradient parameter and porosities on vibrational characteristics of size-dependent FG nanoplates.

• 한국주조공학회지
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• 제10권4호
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• pp.309-315
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• 1990

Aluminum alloy matrix composites reinforced by SiC particles were prepared by rheocompocasting, a process which consists of the incoporation and distribution of reinforcement by stirring within a semi-solid alloy. When the volume fraction of SiCp and stirring speed were fixed, the dispersion of SiCp in Al-matrix alloy depended on stirring time and solid volume fraction in slurry. The results were as follows : 1) As a dispersed SiCp during stirring at $647^{\circ}C$ in 6063-Al alloy, SiC was better dispersed than that other temperature, where solid volume fraction was 43% in slurry. 2) When increased solid fraction in slurry, rate of dispersing SiC increased during stirring and porosities decreased in matrix alloy after casting. 3) Inspite of stirring with 800rpm, since solid particles of matrix alloy in slurry joined each other and occured joining growth, so that SiC was not dispersed into solid particle.

• Journal of Welding and Joining
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• 제28권6호
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• pp.58-62
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• 2010

In this study, the bead-on-plate welding were conducted by using GMA welding and plasma-GMA welding on Al 5052 and, Al 6061 plates. For these processes, the maximum welding speeds for full penetration were compared, and various weld qualities such as bead appearance, cross-section, cracks and porosities were examined. Faster welding speed, cleaner bead surface and more stable drop transfer could be achieved by plasma-GMA welding, compared with GMA welding.

• E2M - 전기 전자와 첨단 소재
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• 제10권3호
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• pp.255-261
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• 1997

In this study, pore-containing barium titanate ceramics were prepared with different porosities and pore sizes, in order to better understand how porosity and pore size affect electrical breakdown of barium titanate ceramics. A granulated barium titanate powder was mixed with three grades of commercial polymer microspheres up to 11wt%. The electrical breakdown test was performed at two different temperatures of 30.deg. C(below Tc) and 150.deg. C(above Tc) for samples immersed in a silicon oil bath using a 60kV de power supply. Electrical breakdown strength of pore containing barium titanate ceramics with porosity lower than 10% decreased as pore size and porosity increased. However, above the 10% porosity region, electrical breakdown strength decreased as the pore connectivity increased. From the experimental results, an optimum electrical breakdown model is proposed in an attempt to explain the effect of pores.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.240-240
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• 2010

In this paper, in these case of photoelectrode using UV treatment after oxygen solar conversion efficiency is increased. According to oxygen injection UV treatment will removal residual organics and increase the TiO2 surface area but also UV treatment can affect the same chemical action of ozone treatment. More porous networks and larger porosities were obtained in the TiO2 films prepared UV treatment after oxygen injection.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제6권1호
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• pp.7-14
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• 2003

The interaction of monochromatic incident waves with a submerged horizontal porous membrane is investigated in the context of two-dimensional linear hydro-elastic theory. It is assumed that the membrane is made of material with very fine pores so that the normal velocity of the fluid passing through the porous membrane is linearly proportional to the pressure difference between two sides of the membrane (e.g. Darcy's law). Using the Eigen-function expansion method, the wave-blocking performance of a submerged horizontal porous membrane is tested with various membrane tensions, porosities, lengths, and submerged depths. It is found that an optimal combination of design parameters exists for given water depth and wave characteristics.