• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.71-77
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• 2013

Aluminium powder as reductant in aluminothermy process needs a fine particle size under 200 mesh, but it is not easy economically to make that because of its high ductility and powder production cost. In order to reduce the production cost of fine aluminum powder as reductant of $Mn_3O_4$ waste dust, therefore, the properties of aluminium alloy powder were investigated. Aluminium alloy ingot containing large amount of manganese can be crushed easily because of its intermetallic compounds having brittle properties. The manganese is also main element in ferro-manganese. We can obtain economically Al-15%Mn alloy powder by mechanical comminution process. And the result of thermite reaction using Al-15% Mn alloy powder instead of pure Al powder showed the fact that can be obtained the ferro-manganese which have a high purity in case of using pure aluminium powder as reductant. The recovery of manganese from $Mn_3O_4$ waste dust with Al-15%Mn alloy powder was higher level of about 70% than about 65% in case of using aluminium powder, that is due to lower spatter loss.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.31-31
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• 2009

In this paper, RFID antenna is designed and realized for UHF (860 ~ 960 MHz) application. Aluminium is used for patterning on polythelene terephalate (PET) substrate using etching process. The thickness of the substrates is 50 ${\mu}m$ and for copper and aluminium, the thickness is typically 18 ${\mu}m$ or 35 ${\mu}m$ and 10 ${\mu}m$ respectively. As a result of simulation, maximum return loss is indicated 0.04 dB at 960 MHz and 0.08 dB at 900 MHz.

• Corrosion Science and Technology
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• v.2 no.1
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• pp.30-35
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• 2003

In this study, sand cast AZ91E and zirconium grain refined MEZ are representative of two typical groups of magnesium alloys: those containing aluminium and those containing no aluminium but with zirconium as a grain refiner. The corrosion performance of these two alloys was evaluated and compared in 5%wt NaCI solution through measurements of weight loss and polarisation curves and examination of microstructure. Corrosion damage of AZ91E was deeper and more localised than that of MEZ, while MEZ had a lower rate of cathodic hydrogen evolution and a higher rate of anodic dissolution than AZ91E. These differences in behaviour can be related to the differences in microstructure and chemical composition between the two alloys.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.82-89
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• 2007

Sound transmission characteristics are investigated on the corrugated steel and aluminium extruded panels used for railway vehicles. Sewell-Sharp-Cremer(SSC) model, equivalent orthotropic plate model and equivalent mass law are applied to predict the sound transmission loss. The predicted values of the sound transmission loss are compared with the measured values. The reliability and the limitation of the prediction models are investigated. For the corrugated panels and honeycomb panels, the coincidence and local resonance severely deteriorate the sound insulation performance around the corresponding frequency bands. The result of the study shows that the equivalent orthotropic plate model and the SSC model can be used as good prediction models, if the coincidence frequency or local resonance frequency is correctly applied.

• Korean Journal of Materials Research
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• v.3 no.4
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• pp.372-380
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• 1993

In order to improve the oxidative resistance of carbon/carbon composites, aluminium-isopropoxide and aluminium-tri-sec-butoxide sol were coated on the surface of 2D--carbon/carbon composiles and the effects uf coating were investigated. The effects of oxidative resistance were dominant in the case of catalyst/alkoxide mole ratio, 0.07, and $H_2O$/alkoxide mole ratio, 100. Through the dynamic TGA analysis with the heating rate of 20%/min, oxidative initiation tempera~ ture was enhanced about $80^{\circ}C$. The oxidative resistance effects of alkoxide sol were improved according to the times of coating. Also the 20% weight loss time of coated samples by TGA analysis was 20% better than that of un~ coated samples. The thickness of 1^{st} coated layer was about 3${\mu}$m and that of $2^{nd}$ and $3^{nd}$ coated layers was about respectively 4~5${\mu}$m and the weight loss were increased with the increasing of thermal shock test times.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2185-2190
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• 2008

In a high speed train, multi-layered panels for floor, side wall and roof are important sound insulating part. As these multi-layered panels require high bending strength vs. weight, corrugated steels or aluminium honeycomb panel are generally used. However, with some inevitable factors, these panels show lower sound insulation performance than that of the plate with the same weight. Transmission loss(TL) often severely decreases in a particular frequency range because of the decrease of the critical frequency, occurrence of local resonance modes and cavity resonance modes, which are not shown in a plate. In this study, frequency range and cause of the TL drop are investigated on the corrugated and honeycomb panels.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.11
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• pp.916-921
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• 2012

This research measured the dielectric properties of silicone rubber with various hardness in 100 Hz~3 MHz, $30{\sim}170^{\circ}C$ conditions. When the hardness increases from 65 degree to 75 degree, the dielectric loss increased within frequency range of 100 kHz~3 MHz and was a little change in dielectric loss within temperature range of $90^{\circ}C{\sim}170^{\circ}C$. Thermogravimetric Analysis (TGA) showed the weight change rate increased a little while heated until $800^{\circ}C$. Scanning Electron Microscope (SEM) measurement showed that Aluminium Trihydroxide($AlOH_3$) which acts as a reinforcement agent reduced the size of the particles as the hardness increased.

• Journal of Industrial Technology
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• v.37 no.1
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• pp.1-4
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• 2017

Speeding up of railway vehicles requires weight reduction of the vehicle body. However, when the vehicle body is lighter, the sound insulation performance for blocking the noise from the outside is reduced. Aluminum is an important material used in the bodywork of transportation vehicles such as railway vehicles, aircraft, and automobiles. In this study, the bending stiffness and sound insulation performance of foamed aluminum with sandwich structure are investigated experimentally. The transmission loss is measured in accordance with the international standard ASTM E 2249-02. The mass-law deviation is used to evaluate the sound insulation performance per weight. In order to examine the applicability of the foamed aluminum sandwich panel to railway vehicles, the analysis of bending stiffness and an experimental review are carried out at the same time.

• Journal of Applied Reliability
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• v.7 no.1
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• pp.23-29
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• 2007

Probe card is a test component which is to classify the known good die with electrical contact before the packaging in the ATE (automatic testing equipment). Conventional probe tip was mostly needle type, it has been difficult to meet with conventional type, because of decreasing chip size, pad to pad pitch and pads size increasingly. For that reason, probe cards using MEMS (micro electro mechanical system) technology have been developed for various semiconductor chips. In this paper, Area Array type MEMS Probe tip was designed,, fabricated, and characterized its mechanical and electrical properties. The authors found that good electrical characteristics under $1{\Omega}$ were acquired with gold (Au) and aluminium (Al) pad contact test over 0.5gf and 4gf respectively. And, contact resistance variation under $0.1{\Omega}$ were achieved with 100,000 times of repetition test. And, insertion loss (IS) for high frequency operation was ascertained over 300MHz at -3dB loss.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.73-78
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• 2008

The fire hazards and combustion heat of puzzle mats in group day care home were analysed using variable external irradiation level. The fire hazards such as ignition time, ignition temperature, mass loss rate, and flame temperature profile were measured. Incident heat fluxes of $15kW/m^2$, $20kW/m^2$, $25kW/m^2$, $35kW/m^2$, $50kW/m^2$ and $75kW/m^2$ were selected for these experiments. All samples were tested in the horizontal orientation and were wrapped in a single layer of aluminium foil. Each sample was nominally 20mm thick and 100mm square. Five samples of puzzle mat were tested in the study : Type A, B, C, D and E. Type A, B and C are all general grades whereas Type D and E are both Flame retardant grades. As results, Type E of FR-grade showed the best characteristics in safety of the early fire from ignition time, critical heat flux, and ignition and flame temperature data of this study. All specimen of G-grade(Type A, B and C), however, showed the weak in safety of fire.