• Journal of Soil and Groundwater Environment
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• v.15 no.6
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• pp.37-45
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• 2010

Surfactant-enhanced ozone sparging (SEOS), an advanced version of SEAS (surfactant-enhance air sparging) was introduced in this study for the first time for removal of non-volatile contaminant from aquifer. The advantages of implementing SEAS, enhanced air saturation and expanded zone of sparging influence, are combined with the oxidative potential of ozone gas. Experiments conducted in this study were tow fold; 1-dimensional column experiments for the changes in the gas saturation and contaminant removal during sparging, and 2-dimensional box model experiment for the changes in the size of zone of influence and contaminant removal. An anionic surfactant (SDBS, sodium dodecylbenzene sulfonate) was used to control surface tension of water. Fluorescein sodium salt was used as a representative of watersoluble contaminants, for its fluorescence which is easy to detect when it disappears due to oxidative degradation. Three different gases (air, high-concentration ozone gas, and low-concentration ozone gas) were used for the sparging of 1-D column experiment, while two gases (air and low-concentration ozone gas) were used for 2-D box model experiment. When SEOS was performed for the column and box model, the air saturation and the zone of influence were improved significantly compared to air sparging without surface tension suppression, resulted in effective removal of the contaminant. Based on the experiments observations conducted in this study, SEOS was found to maintain the advantages of SEAS with further capability of oxidative degradation of non-volatile contaminants.

• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.22-29
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• 1995

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria can act as efficient contaminant carriers. When such carriers exist in a porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and a stationary solid matrix phase. Contaminant can be present in either or all of these phases. In this study, a mathematical model based on mass balances is developed to describe the transport and fate of biodegradable contaminant in a porous medium. Bacterial mass transfer mechanism between aqueous and solid matrix phases, and contaminant mass transfer between aqueous and bacterial phases are represented by kinetic models. Governing equations are non-dimensionalized and solved to analyze the bacteria facilitated contaminant transport. The numerical results of the facilitation effect match favorably with experimental data reported in the literature. Results show that the contaminant transport can be described by local equilibrium assumption when Damkohler numbers are larger than 10. Significant sensitivities to model parameters, particularly bacterial growth rate and influent bacterial concentration, were discovered.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1673-1675
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• 1996

We have studied the effect of surface tension and flow rate of contaminants, wettability, frequency of applied voltage dependence of tracking breakdown. As the flow rate of contaminant is increasd, the surface resistivity is decreased, and the leakage current is increased, the time to tracking breakdown is decreased. It is found that time to tracking breakdown depends on the frequency of contaminant, that is difference of wettability. And as the frequency of applied voltage is increased, time to tracking breakdown decreased.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.66-71
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• 2023

This paper describes a hybrid cleaning method of silicon wafer combining nano-bubble and ultrasound to remove sub-micron particles and contaminants with minimal damage to the wafer surface. In the megasonic cleaning process of semiconductor manufacturing, the cavitation induced by ultrasound can oscillate and collapse violently often with re-entrant jet formation leading to surface damage. The smaller size of cavitation bubbles leads to more stable oscillations with more thermal and viscous damping, thus to less erosive surface cleaning. In this study, ultrasonic energy was applied to the wafer surface in the DI water to excite nano-bubbles at resonance to remove contaminant particles from the surface. A patented nano-bubble generator was developed for the generation of nano-bubbles with concentration of 1×10⁹ bubbles/ml and nominal nano-bubble diameter of 150 nm. Ultrasonic nano-bubble technology improved a contaminant removal efficiency more than 97% for artificial nano-sized particles of alumina and Latex with significant reduction in cleaning time without damage to the wafer surface.

• The Journal of Information Technology
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• v.8 no.2
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• pp.85-91
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• 2005

We studied a pollution mechanism for simulation of contamination environment in industrial concentrated area of around a metropolitan that made to circulated flow in the chamber. In case of the virgin both side of EPDM or Silicon insulator, we confirmed that the pollution to much more than service insulator in the field. Also contamination of initial state of the virgin didn't falling in spite of physical outside factor easily. This study confirmed to that the silicon was too much accumulated pollution contrast to EPDM insulator from scatter(spray) point to regular interval position use the Kaolin contaminant in the chamber. There are effected to the hydrophobicity of polymer insulator due to the pollution. In ceramic insulator, we get to know that pollution is much more at the Post insulator with vertical than with horizontal setup insulator.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.115-119
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• 2003

Pollutants from industry, mining, agriculture, and other sources have contaminated sediments in many surface water bodies. Sediment contamination poses a severe threat to human health and environment because many toxic contaminants that are barely detectable in the water body can accumulate in sediment at much higher levels, the purpose of this study was to make convenient sampling method and optimal treatment of sediment for water quality improvement in reservoir or stream based on an evaluation of degree of contamination. Results for analysis of S-reservoir sediments were observed that copper concentration of almost areas were higher than the regulation of soil pollution (50 mg/1) for the riverbed. S-stream sediments were observed that copper, arsenic and TPH concentration of almost areas were exceeded soil pollution concerning levels for factorial areas. We used Remscreen(version. 1.0) program which is contaminated soil recovery program to select optimal treatment method of contaminant sediments. The result was shown in the order of Thermal Calcination > Excavation, Retrieval and Off-site Disposal(comparative less then contaminant) > Low Temperature Thermal Desorption + Solidification/Stabilization.

• Wind and Structures
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• v.3 no.1
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• pp.11-21
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• 2000

This paper presents results of modeling of the passive contaminant diffusion from a continuous line finite-size source located on the underlying surface of a neutral near-ground atmospheric layer obtained by using the non-local two-parameteric turbulence model and the transport equation of mean concentration. In the proposed diffusion model the turbulent diffusion coefficient changes not only with the vertical coordinate but also with the distance downstream from the source according to the experimental data. The results of the modeling reproduce structural features of the concentration field.

• Economic and Environmental Geology
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• v.46 no.5
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• pp.445-453
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• 2013

The Uiseong Tapriri Five-Storied Stone Pagoda (National Treasure No. 77) is typical stone cultural heritage in Unified Silla Dynasty, Korea. The pagoda has been occurred black, brown discoloration and microcrack, exfoliation, granularity decomposition with white discoloration because of continuous weathering. As the results of analysis for the contaminants, chemical weatherings are generated that black contaminant by manganese oxide, brown contaminant by iron oxide, white contaminants by gypsum and taranakite. And physical weatherings, such as microcrack, exfoliation, are occurred by salt(gypsum) crystallization. Therefore, these need to remove the contaminants according to the conservation treatment manual, and regular monitoring using P-XRF to preserve long-term the Five-Storied Stone Pagoda at Tapri-ri, Uiseong.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1434-1436
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.484-487
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• 2005

In order to get the surface characteristics of the HDI of HDD, the surface damage mechanisms must be totally understood. Particle contamination in hard disk drives is a big concern in today's magnetic recording industry since they are major sources of reliability problems. Namely upon contact with the slider or a contaminant particle, the disk may be scratched or the particles may be embedded into the disk surface. In this work, comparison of scratches was made between those found on actual hard disks and those created using a scratch tester. It was found that ramp loading method is an effective way to make similar scratches as the actual ones. From the ramp loading condition, the relationship between the pressure and the scratch track width could be identified.