• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.11a
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• pp.59-62
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• 2002

Recently, advanced system for water and wastewater treatment is introduced and operated because of water pollution and etc. One of this System makes use of O3(Ozone) for water and wastewater treatment. In airtight concrete structure, waterproofing phase as well as water are affected by strong oxidative O3 in the long-term. For this reason, material stability against O3 is examined. Consequently, the purpose of this study is to find out material stability an object of epoxy resin by way of accelerated O3 testing.

• Journal of IKEEE
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• v.21 no.3
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• pp.252-255
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• 2017

$Mo_xW_{1-x}Si_2$ heaters were fabricated by self-propagating high-temperature synthesis (SHS) process and post sintering process. To validate the reliability of the $Mo_xW_{1-x}Si_2$ heaters, the accelerated life test (ALT) was conducted, and then lifetime to $Mo_xW_{1-x}Si_2$ heaters was estimated by using Minitab programs. Also, the failure analysis of $Mo_xW_{1-x}Si_2$ heaters after ALT was performed through electrical and structural properties. As the results, it was confirmed that the dominant failure mode of $Mo_xW_{1-x}Si_2$ heaters is the crack formation in heaters and the delamination of protective $SiO_2$ layers.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.513-518
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• 2003

Recently, advanced systems for water treatment are introduced for water quality improvement. One of those systems is water treatment method using ozone($O_3$). For it has strong oxidizing energy, it is necessary to have materisl stability against $O_3$. In this paper, epoxy resin specimens using as anticorrosive material of concrete structure for drink water are used to serve as a material of deterioration evaluation. It is to be studied weight loss, surface corrosion of specimens, ingredient analysis of floating particle, a solute of chemical ingredient by way of accelerated ozone testing. As the results of experiment, specimen weight is decreased. The surface of specimen is eroded heavily and showed a loss of gloss and floating particle, and in the stability for drinking water, harmful ingredient is not detected in the water.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.1186-1191
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• 2011

Composition which was used as a white smoke grenade consists of Aluminium(Al), Hexachloroethane(HCE) and Zinc Oxide(ZnO), etc. there is a possibility of misfire due to long term storage and there are very few reports on the mechanism behind misfire. In this study, an experimental method known as accelerated degradation testing is used to investigate the chemical mechanism resulting in misfire. The mechanism of chemical change during long term storage was analyzed with XRD and FT-IR. Analysis results suggest that a part of HCE consisting of the white smoke grenade disappeared and the other part was combined into $ZnCl_2$, $AlCl_3$, as a recycled intermediate product under closed system.

• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.399-406
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• 2017

CaO-based by-product, which consist of CaO, $SO_3$, $Al_2O_3$ and so on, has being used to raw materials of CaO compound. When It was applied to recycling water of remicon, concrete performance can be enhanced because hydration reaction of powder material is accelerated. In this study, activated-sludge, which was putted desulfurization gypsum of CaO-based in recycling water, was manufactured to verify effect of them, and then they was investigated by characteristics of cement matrix and mortar. As a results, they indicated reduction of setting time and high soundness in cement matrix, and acceleration of hydration reaction can be verified by XRD analysis. Also, it can be maintained good workability if water content by usage of desulfurization gypsum, which used for production of activated-sludge, was adjusted. In addition, it can be verified strength development by activated-sludge although cement content by usage of desulfurization gypsum was reduced.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1993.10a
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• pp.97-102
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• 1993

The application of epxy composite materials for the outdoor insulating systems has some significant advan-tages compared with conventional inorganic materials, that is low weight in combination with high mechanical strength, small dimensions and design versatility. The paper describes the results of high voltage investigations carried out different aging types of epoxy resin insulator and silicone grease coating. The insulators have been exposed 3000 hours to weather-o-meter and 12 months to outdoor. In this connection, the main study of paper is form the basis of develop-ment of principal technologies of epoxy composites which ard: (1)manufacturing of insulator, (2)high vol-tage testing under dry and wet condition, (3)mechani-cal properties, (4)accelerated weather-ometer test and outdoor exposed, artificial polution.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.43-55
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• 2000

In traditional electronic packages the die and the substrate are interconnected with fine wire. Wire bonding technology is limited to bond pads around the peripheral of the die. As the demand for I/O increases, there will be limitations with wire bonding technology. Flip chip technology eliminates the need for wire bonding by redistributing the bond pads over the entire surface of the die. Instead of wires, the die is attached to the substrate utilizing a direct solder connection. Although several steps and processes are eliminated when utilizing flip chip technology, there are several new problems that must be overcome. The main issue is the mismatch in the coefficient of thermal expansion (CTE) of the silicon die and the substrate. This mismatch will cause premature solder Joint failure. This issue can be compensated for by the use of an underfill material between the die and the substrate. Underfill helps to extend the working life of the device by providing environmental protection and structural integrity. Flux residues may interfere with the flow of underfill encapsulants causing gross solder voids and premature failure of the solder connection. Furthermore, flux residues may chemically react with the underfill polymer causing a change in its mechanical and thermal properties. As flip chip packages decrease in size, cleaning becomes more challenging. While package size continues to decrease, the total number of 1/0 continue to increase. As the I/O increases, the array density of the package increases and as the array density increases, the pitch decreases. If the pitch is decreasing, the standoff is also decreasing. This paper will present the keys to successful flip chip cleaning processes. Process parameters such as time, temperature, solvency, and impingement energy required for successful cleaning will be addressed. Flip chip packages will be cleaned and subjected to JEDEC level 3 testing, followed by accelerated stress testing. The devices will then be analyzed using acoustic microscopy and the results and conclusions reported.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.200-207
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• 2020

MoSi₂, (Mo_1/2W_1/2)Si₂, and WSi₂ powders were synthesized by self-propagating high-temperature synthesis (SHS) method. The synthesized powders were heat-treated at 500, 1,000, 1,200, 1,300, 1,400, 1,500 and 1,600℃ in ambient atmosphere. Oxidation of Mo-W silicide powder was found at low temperature of 500℃. XRD structure analysis and DTA/TG data showed that MoO₃ was formed with 500℃ heat treatment for 1 hour, and that it was α-cristobalite phase that was formed with 1200℃ heat treatment, not α-quartz phase which is commonly found and stable at room temperature. Existence of W accelerated decomposition at both low and high temperature. Fully sintered MoSi₂ and (Mo_1/2W_1/2)Si₂ specimen did not show decomposition or weight loss by oxidation, with 1 hour heat treatment at either low or high temperature. Notably, it was difficult to sinter WSi₂ because of oxidation reaction at low temperature.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.396-401
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• 2010

Tolclofos-methyl is one of the most widely used organophosphorous pesticides in control of soil-borne diseases in ginseng field. In Korea, residues of tolclofosmethyl in ginseng and cultivation soil is quite often detecting. The objective of this study was to know the possibility for the accelerated degradation of tolclofos-methyl by various chemical treatment under soil slurry condition. The degradation of tolclofos-methyl was accelerated by zerovalent metals treatment in soil slurry. The degradation rate of tolclofos-methyl was found to be at higher zerovalent zinc than unannealed zerovalent and annealed zerovalent iron. The effect of different sizes of zerovalent iron on tolclofos-methyl degradation was showed that the smaller size of zerovalent iron, the greater the degradation rate. In aqueous solution of pH 4.0 below the degradation rate of tolclofos-methyl was very high. Under this experimental condition, tolclofos-methyl degradation was the greatest at 2% (w/v) of ZVI under 0.1 N of HCl in 24 hours, the degradation rate was 94.4%. By testing various chemicals, it was found that $Fe_2(SO_4)_3$ as iron source showed better for degrading tolclofos-methyl in $H_2O_2$ 500 mM treatment and sodium sulfite also showed the degradable possibility tolclofos-methyl in soil slurry.

• Korean Journal of Materials Research
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• v.16 no.11
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• pp.681-686
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• 2006

Plasma nitrocarburising and plasma post oxidation were performed to improve the wear and corrosion resistance of S45C and SCM440 steel by a plasma ion nitriding system. Plasma nitrocarburizing was conducted for 3h at $570^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the ${\varepsilon}-Fe_{2-3}$(N, C) phase. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite ($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the $15{\sim}25{\mu}m$ ${\varepsilon}-Fe_{2-3}$(N, C) compound layer was obtained by plasma post oxidation. A salt spray test and electrochemical testing revealed that in the tested 5% NaCl solution, the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer. Throttle valve shafts were treated under optimum plasma processing conditions. Accelerated life time test results, using throttle body assembled with shaft treated by plasma nitrocarburising and post oxidation, showed that plasma nitrocarburizing and plasma post oxidation processes could be a viable technology in the very near future which can replace $Cr^{6+}$ plating.