• Design & Manufacturing
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• v.12 no.1
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• pp.26-30
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• 2018

The aluminum chassis drive gear manufacturing process improvement has been very effective in both technical and economic aspects. Technology for Shear mold design technology, mold material selection and processing technology, and press molding technology has improved greatly overall. In the meantime, it is necessary to clarify the causes of defects that occur frequently due to lack of technology, Based on this, it is meaningful that it has secured the ability to respond to new product development and molding in the future. By applying these technologies, we plan to expand not only the drive gear chassis, but also various types of press forming such as frame, handle, various fastening parts of system window. In addition, the ability to develop precision products in the future is expected to become a driving force in further enhancing the competitiveness of companies.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.527-534
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• 1995

In this research, the emphasis was focused on the rearrangement and densification behavior of CaO particles when the aluminum was added to improve the hydration resistance. For the case of 0.5vol% Al added specimen, the rearrangement of CaO particles due to liquid aluminum was terminated near 140$0^{\circ}C$ where the theoretically calculated fractional volume of solid reached 0.74 under Ar atmosphere. The density of the specimen sintered at 155$0^{\circ}C$ for 5hrs reached 96% of relative theoretical density when the ambient was switched to O2 at intermediate and final stages of the sintering. The weight gain due to the hydration after 60 days under 72% of relative humidity at 26$^{\circ}C$ was less than 1%.

• Journal of the Korean Ceramic Society
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• v.26 no.3
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• pp.445-451
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• 1989

Hydrolysis of aluminum isopropoxide with excess water in the presence of excess isopropyl alcohol resulted in the formation of boehmite in independence of temperature of hydrolysis and aging. Stoichiometric and substoichiometric amount of water hydrolyzed aluminum isopropoxide to pseudo-boehmite and amorphous one, respectively. $\alpha$-Al2O3 with 0.3${\mu}{\textrm}{m}$ in median size was produced by calcination of boehmite, bseudo-boehmite and amorphous boehmite at 125$0^{\circ}C$, 120$0^{\circ}C$, and 115$0^{\circ}C$ for one hour, respectively. Singnificant reduction in particle size was found during transition from $\theta$-Al2O3 to $\alpha$-Al2O3. $\alpha$-Al2O3 produced in this study was relatively uniform spherical and its purity was found to be over 99.9%.

• Journal of the Korean institute of surface engineering
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• v.26 no.5
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• pp.271-279
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• 1993

Experiments on electorchemical etching of aluminum foils with high cubic textures were carried out in this study. Etching behaviours and pit shapes with respect to various conditions of eletrochemical etching were in-vestigated. When HCl and NaCl solutions were used as electrolytes, the highest capacitanes were observed in solutions of 1MHCl and 5M NaCl. It was foundd that capacitance was improved by addition of H2SO4 to HCl so-lution which is considered to be due to the suppression of oxide film formation on the aluminum surface. The homogeneous distribution of each pits obtained in the HCl solution, while the degree of weight loss was lowest in the Nacl solution. The best etching properties in 1M HCl solution were obtained at the etching condi-tions of 0.15 A/$\textrm{cm}^2$, 150sec and$ 90^{\circ}C$.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.20-26
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• 2014

In this paper, yield stress, tangent modulus and failure strain were varied to ascertain the influence of impact response such as impact force histories and residual energy. And the buckling behavior of FML(Fiber Metal Laminates) were analyzed using numerical method. A number of analyses on FML and aluminum panel were conducted for shear and compression loading to compare the capability of stability. And to evaluate the static performance, static analysis has performed for box beam structure. Low-velocity impact analysis has performed on FML made of aluminum 2024 sheet and glass/epoxy prepreg layers. And the buckling and static performance of FML have been compared to aluminum using the analysis results. For the comparison of structural performance, similar analyses have been carried out on monolithic aluminum 2024 sheets of equivalent weight.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.16-26
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• 2014

T-Burner tests of an Al/HTPB propellant in conjunction with a Pulsed DB/AB Method were conducted to find an acoustic amplification factor. Aluminum-free and aluminum-heavy propellants were examined. Instant surface ignition was successfully made by the use of a supplementary propellant of fractionally higher reaction rate. With the presence of higher aluminum concentration in the propellants, the pressure perturbations were promptly damped down and the pressure fluctuations were no longer dispersive. Addition of aluminum particles into the propellant was advantageous for stabilizing pressure-coupled unstable waves.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.3
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• pp.193-201
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• 2006

Thermal performance model was developed for a cross-flow aluminum heat exchanger with relatively short passage. Appropriate heat transfer coefficient and friction factor equations for laminar channel flow were obtained considering developing regions. The heat exchanger was analyzed using the unmixed cross-flow ${\epsilon}$-NTU relationship considering leak-age between streams. Thermal contact between corrugations and plates was also considered. Tests were separately conducted for two samples - one made of non-treated aluminum sheets, and the other made of varnish-treated ones. The samples were made by stacking corrugations and plates one after another. The model adequately predicted the thermal performance and pressure drop of the non-treated heat exchanger. The thermal performance of the varnish-treated one was $7{\sim}12%$ overpredicted, and the pressure drop of the varnished-treated heat exchanger was $5{\sim}15%$ underpredicted. The air leakage ratio of the non-treated heat exchanger was $23{\sim}26%$. The ratio decreased to less than $10%$ with the varnish treatment.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.193-200
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• 2015

Purpose: The purpose of this study was to investigate the energy saving effects and characteristics of plant growth in a greenhouse with an aluminum multi-layer curtain compared to a greenhouse with non-woven fabric. Method: The dimensions of both greenhouses $43m{\times}3.6m{\times}8m(L{\times}H{\times}W)$, and both used hot air heater systems for maintaining a constant temperature $15^{\circ}C$. Heating characteristics such as solar intensity, inside and ambient temperatures, and fuel consumption were measured and analyzed. Results: The changes of average temperature of both greenhouses during a 15-days (December 06 - 20) showed approximately $26^{\circ}C$ at around 2 pm when the ambient temperature was highest. The greenhouses were set by the heater to keep a temperature of $15^{\circ}C$ from 4 pm to 8 am the following day. The average heat loss (for 15 days) from the greenhouse with an aluminum multi-layer curtain was $161.2-268.4kJ/m^2{\cdot}h$ during the daytime and $152.3-198.1kJ/m^2{\cdot}h$ during the nighttime. The average heat loss (for 15 days) from the greenhouse with non-woven fabric was $155.7-258.9kJ/m^2{\cdot}h$ during the daytime and $144.9-207.0kJ/m^2{\cdot}h$ during the nighttime. The total heat loss (for one day) from the non-woven fabric system was $7,960kJ/m^2$($2,876kJ/m^2$ during the daytime, $5,084kJ/m^2$ during the nighttime). The heat supply over 36 days for the non-woven fabric system was higher than the aluminum multi-layer curtain system by $616.3-65,079.4kJ/m^2$. Conclusions: These results suggest that a greenhouse with an aluminum multi-layer curtain could save energy usage by 35% over a greenhouse with non-woven fabric.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.31-37
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• 2015

The cases of radiographic inspection for medical diagnosis in Korea have been continuously increasing year after year, which pays particularly more attention to CT which occupies over the half of medical radiation exposure. To find an effective alternative for reducing radiation exposure, the researchers conducted comparative experiments using some shields made of bismuth, aluminum 6mm, and silicone 22mm. These shielding materials have been used to reduce the entrance surface dose (ESD) on lenses, maintaining the CT number, noise, and uniformity in brain CT scanning which forms the largest part in CT scanning these days. These experiments showed that the doses in the spiral scan parallel to IOML and the conventional scan in Bismuth were 26.41% and 17.52%, respectively; in Aluminum 18.24% and 9.39%; in Silicone 19.47% and 14.39% lower than compared with those in the cases without any shields. In the items of the CT number, noise, and uniformity, the bismuth shield satisfied exceedingly the standards of the phantom image test while aluminum and silicone were within. To keep the graphic quality and get good shielding effect, we recommend the silicone shield which can be manufactured and purchased with ease.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.409-412
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• 2005

Free-standing nanoporous alumina membrane microtubes with different shapes (rectangular and cylindrical tubes) and variable dimensions were easily fabricated by direct anodization of the aluminum templates of the specified shapes (strip and wire) and dimensions during the electrochemical reaction.