• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.244-248
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• 2003

Unused well and improperly abandoned wells are a significant threat to groundwater quality. If abandoned wells is not properly filled with material, it can directly channel to flow contaminated and surface water into subsurface and groundwater. The abandonment process is over viewed and the method of filling with impermeable and permeable material is presented for the purpose of proper well abandonment work.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.175-178
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• 2002

The purpose of this research is to evaluate the effect of microemulsion on the remediation of soil contaminated with organic materials. The laboratory tests were conducted to confirm the ability of microemulsion as remediation agent and compare remediation efficiency in microemulsion process with soil washing. In the test, pyrene was used as organic contaminant and alkylpolyethoxylates(C$_4$E$_1$) was used as surfactant. Microemulsion in the $C_4$E$_1$-water-decane mixture was formed in the range of 22 and 48$_{o}$ C at surfactant contents V=55%. Extraction was completed within 30 min and about 90% pyrene was removed. Seperation of pyrene with oil phase lowering temperature was sufficient for application in a multistep process.s.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.139-144
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• 2003

1, 4-dioxane is a recalcitrant pollutant found in contaminated ground waters and industrial effluents. Conventional water treatment techniques are limited to treat this compound effectively. In this study, $O_3$／$H_2O_2$ oxidation process was used to eliminate 1, 4-dioxane in water and to enhance the biodegradability. Several factors affecting biodegradability enhancement were investigated. The relationship between initial oxidation rate of 1 A-dioxane and BOD enhancement rate has been determined, a kinetic model has been proposed. $H_2O_2$ concentration and pH had a proportional relation with biodegradability of 1, 4-dioxane, but in case of ozone, there was no relationship with biodegradability. 1, 4-Dioxane removal efficiencies had good agreement with the biodegradability.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_4
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• pp.165-172
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• 2001

We investigated the optimal experimental conditions and reaction kinetics for the decompositions of PCE, TCE, naphthalene, and chloroform using conventional Fenton oxidation process. Additionally, the influence of pH on the decompositions of PCE was also evaluated. The results indicated that the optimal pH value was around 3. The dosage of Fenton's reagent and the molar ratio of hydrogen peroxide to ferrous ion for an approximately complete decomposition was found to depend on the properties of the organic compound. Due to their unsaturated structures, the results show that PCE, TCE, and naphthalene could be all effectively decomposed by Fenton's reagent oxidation. Their unsaturated structures could be mostly destoyed within first 1-2 minutes at a low dosage with an certain molar ratio of hydrogen peroxide to ferrous ion. However the saturated compound such as chloroform was more difficult to decompose even with a relatively high dosage of Fenton's reagent.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.179-184
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• 2015

Quadrupole Mass Spectrometers (QMS) is a very useful tool in vacuum process diagnosis. Tungsten filament based ion sources are vulnerable to contamination from process gas monitoring. Common symptoms of quadrupole mass spectrometer malfunction is appearance of unwanted contaminant mass peaks or no detection of any ion peaks. We disassembled used quadrupole mass spectrometer and found out black insulating deposits on inside of ion source parts. Five steps of cleaning procedure were applied and almost full restoration of functions were confirmed in two types of closed ion source quadrupole mass spectrometer. By using a numerical modeling (CFD-ACE+) technique, the electric potential profile of ion source with/without insulating deposit was calculated and showed the possibility of quadrupole mass spectrometer malfunction by the deterioration of designed potential profile inside the ion source.

• Nuclear Engineering and Technology
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• v.39 no.6
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• pp.731-736
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• 2007

Radioactive organic wastes containing acetone, alcohol, and particularly tributyl phosphate (TBP)/dodecane contaminated with uranium are extracted from the PUREX process and the decontamination of related equipment. An evaporation method that utilizes existing DU oxidation apparatuses and ventilation systems and a typical muffle furnace installed with an aspirating system are adopted. A separation method using phosphoric acid especially for the TBP/dodecane waste is also studied and evaluated. The results show that a simple evaporation process is utilizable for wastes containing acetone or alcohol with a lower boiling point. A modified muffle furnace is more appropriate to dispose directly of organic wastes having a higher boiling point, such as TBP/dodecane, without generating a condensed waste solution. It is recommended that, when the uranium concentration of TBP/dodecane waste is much higher than stipulated levels, separation technology should be applied to remove uranium from the mixture. Each type of solvent after separation can then be considered disposable below the regulatory limit in the modified furnace discussed in this study.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.8
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• pp.752-758
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• 2006

A GPS receiver provides much information such as calculated position, speed, heading, status of satellites, current time errors, etc. It is well-known that GPS signals from GPS receiver mounted on moving vehicle are often distorted, contaminated by various noises, and blocked by tunnel or tall buildings. The phenomenon often obstructs correct navigation especially when a vehicle keeps stopping or is moving in low speed. Therefore it is needed to pre-process the signals to adapt it to various applications. In this paper, an algorithm to pre-process the signals is proposed. For this, GPS data obtaining from uNAV GPS receiver are analyzed and classified based on dynamic characteristic. Then, the proposed algorithm is applied to the data and some test results are shown to verify the usefulness of the algorithm.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.140-145
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• 2010

Consolidation in cohesive soils mainly focuses on compressibility of soils, but it affects solute transport in some cases. The consolidation process takes on particular significance for fine grained soils at high water content, such as dredged sediments, but has also been shown to be important for compacted clay liners during waste filling operation. Numerical investigation using CST1 and CST2 was reviewed on consolidation-induced solute transport in this paper, especially with the development of CST2 model, verification by comparing experimental results with numerical simulations, and cases studies regarding transport in a confined disposal facility (CDF) and during in-situ capping. The importance of the consolidation process on solute transport is accessed based on simulated concentration or mass breakthrough curves. Results indicate that neglecting transient consolidation effects may lead to significant errors in transport analyses, especially with soft contaminated cohesive soils undergoing large volume change.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.114-118
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• 2009

PVA (polyvinyl alcohol) brush cleaning method is a typical cleaning method for semiconductor cleaning process especially post-CMP cleaning. PVA brush contacts with the wafer surface and abrasive particle, generating the contact rotational torque of the brush, which is the removal mechanism. The brush rotational torque can overcome theoretically the adhesion force generated between the abrasive particle and wafer by zeta potential. However, after CMP (chemical mechanical polishing) process, many particles remained on the wafer because the brush was contaminated in previous post-CMP cleaning step. The abrasive particle on the brush redeposits to the wafer. The level of the brush contamination increased according to the cleaning run time. After cleaning the brush, the level of wafer contamination dramatically decreased. Therefore, the brush cleanliness effect on the cleaning performance and it is important for the brush to be maintained clearly.

• Structural Engineering and Mechanics
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• v.57 no.1
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• pp.21-43
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• 2016

A conditional probability based approach known as Particle Filter Method (PFM) is a powerful tool for system parameter identification. In this paper, PFM has been applied to identify the vehicle parameters based on response statistics of the bridge. The flexibility of vehicle model has been considered in the formulation of bridge-vehicle interaction dynamics. The random unevenness of bridge has been idealized as non homogeneous random process in space. The simulated response has been contaminated with artificial noise to reflect the field condition. The performance of the identification system has been examined for various measurement location, vehicle velocity, bridge surface roughness factor, noise level and assumption of prior probability density. Identified vehicle parameters are found reasonably accurate and reconstructed interactive force time history with identified parameters closely matches with the simulated results. The study also reveals that crude assumption of prior probability density function does not end up with an incorrect estimate of parameters except requiring longer time for the iterative process to converge.