• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.91-97
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• 2018

Chemical mechanical polishing(CMP) realizes a surface planarity through combined mechanical and chemical means. In CMP process, Preston equation is known as one of the most general approximation of the removal rate. Effects of pressure and relative speed on the mechanical property of Cu CMP has been investigated. On the other hand, The amount of abrasion also increased with changes in pressure and speed, resulting in a proportional increase of temperature during CMP. Especially this temperature is an important factor to change chemical reaction in a Cu CMP. However, when the slurry temperature became higher than $70^{\circ}C$, the removal rate went lower due to abrasives aggregation and scratching occurred on the Cu film. Therefore, it was found that the slurry temperature should not exceed $70^{\circ}C$ during Cu CMP. Finally, authors could increase the pressure, speed and slurry temperature up to a ceratin level to improve the removal rate without surface defects.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.8-13
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• 2019

As increasing demand for precise machining in advanced disciplines, especially in semi-conductor, aeronautical and automotive industries, the magnetic abrasive deburring(MAD) which is able to eliminate micro-sized burr on complex surface in less time has drawn the attention in the last decades. However, the performance of MAD is subject to shape and size of a tool. Therefore, this study aim to identify deburring behavior of MAD in U-type flow channel by measuring the length rate of burr removal in radial distance of the cylindrical tool under four process factors. In order to evaluate the deburring effect of MAD on the surface, finishing regions are divided based on center of the circular cutting tool. As a results, it was defined that the amount of burr removal in a downward direction moving toward flow channel from the top surface was higher than upward direction. This is because the magnetic abrasives were detached from magnetic lines of force due to geometrical shape.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3293-3298
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• 2022

Removing radioactive contaminated metal materials is a vital task during the decommissioning of nuclear power plants to reduce the cost of the post-dismantling process. The laser decontamination technique has been recognized as a key tool for a successful dismantling process as it enables a remote operation in radioactive facilities. It also minimizes exposure of workers to hazardous materials and reduces secondary waste, increasing the environmental friendless of the post-dismantling processing. In this work, we present a thorough and efficient laser decontamination approach using a single-mode continuous-wave (CW) laser. We subjected stainless steels to a surface-removal process that repetitively exposes the laser to a confined region of ~75 ㎛ at a high scanning rate of 10 m/s. We evaluate the decontamination performance by measuring the removal depth with a 3D scanning microscope and further investigate optimal removal conditions given practical parameters such as the laser power and scan properties. We successfully removed the metal surface to a depth of more than 40 ㎛ with laser power of 300 W and ten scans, showing the potential to achieve an extremely high DF more than 1000 by simply increasing the number of scans and the laser power for the decontamination of primary circuits.

• Journal of Wellbeing Management and Applied Psychology
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• v.6 no.1
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• pp.17-22
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• 2023

Purpose: VOCs (volatile organic compounds) are all the organic compounds that react with solar rays and increase the concentration of ozone in the troposphere and are partially also known as carcinogens. The adsorption using activated carbon is usually applied to remove VOCs. Research design, data and methodology: The 20 places of surface coating facilities were selected to evaluate the emission amount of VOCs in Seoul. In addition, the removal efficiency of VOCs in 25 places of automobile coating facilities was evaluated. Results: The average emission amount of VOCs was 10.903 kg/hr from automobile coating facilities, while 3.520 kg/hr from other surface coating facilities. The removal efficiency in adsorption with the combustion catalytic process has the mean value of 87.9% and the regeneration efficiency of activated carbon has the mean value of 95.0%. Conclusions: The removal efficiency in adsorption with the biofiltration process has the mean value of 89.8% and the regeneration efficiency of activated carbon has the mean value of 94.8%. The removal efficiency in the plasma catalyst process has the mean value of 79.3%.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.75-86
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• 2007

This process which has a connection of biofilter and sulfur-limestone has been developed to treat organic substances including BOD, COD and SS etc. and to treat sulfur-limestone is for denitrification.. The whole process consists of chemical reaction tank, sedimentation tank, trickling filter, denitrification tank The trickling filter is equipped with a reactor filled with absorptive filter, and the sulfur denitrification tank is filled with sulfur-limestone mixed media. After setting up practical facilities whose capacity is 60 tons a day, we have observed the removal efficiencies of pollutants through 60 experiments during Summer and Winter seasons. The average concentration of polluted water was BOD for 3.6 mg/L, $COD_{Mn}$ for 11.3 mg/L, SS for 2.8 mg/L, T-N for 8.6 mg/L, and T-P for 0.8 mg/L, and the rate of treatment efficiencies 96.5%, 84.7%, 96.5%, 79.2%, and 80.8%, respectively was found through the experiments. The average treatment efficiency for BOD and $COD_{Mn}$ was 85.0% and 55.7%, respectively and the average removal efficiency for NH4+-N was 84.9% in the trickling filter. The removal efficiency in the denitrification tank is as follows; The removal rate of $NO_3^--N$ was as high as 93.2% within the compass of pH 6.3 to 7.3 through $16.8{\sim}37.0mg/L$ flown into $NO_3^--N$ and $0.1{\sim}8.3mg/L$ outflown. It had observed that this process has implemented highly efficient and advanced treatment without external carbon sources and internal recycle during its process. In conclusion, this process is suitable for a sewerage in a small village due to the merits of low power consumption and easy maintenance.

• Environmental Engineering Research
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• v.25 no.2
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• pp.178-185
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• 2020

The aim of this study is to investigate the degradation of ciprofloxacin (CIP) from its aqueous solutions via different advanced oxidation processes (AOP). The effects of persulfate (PS) concentration, pH, zinc oxide nanoparticles (ZnO-NPs) dose, initial CIP concentration, and reaction time on the degradation of CIP were studied. It was found that the sonochemical (US) degradation is a less efficient process (with removal efficiency of 36%) compared to the sono-nano-chemical (US/ZnO) process which resulted in removal efficiency of 70%. Maximum removal of 99% was obtained using the sono-nano-chemical/PS (US/ZnO/PS) process at a frequency of 60 kHz, time of 10 min, pH of 7, initial CIP concentration of 25 mg/L, and PS concentration of 476.06 mg/L. The addition of PS and ZnO-NPs to the process enhanced the rate of US degradation of CIP. In addition, the kinetic parameters for the US/ZnO/PS process were obtained by fitting the kinetic data into the pseudo-first-order and pseudo-second-order kinetic models. The kinetic data was found to fit into the pseudo-first-order kinetic model than the pseudo-second-order model. The results showed that the AOP using US/ZnO/PS is a promising technique for the treatment of ciprofloxacin containing solutions.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1757-1763
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• 2000

To consider the nutrient removal characteristics of BNR process activating soil microorganisms under the influence of DPB and to clear the characteristics of DPB under anoxic condition was investigated in the this study. The batch tests were conducted using sludge sampled from the BNR process activating soil microorganisms during operation periods. The results of this study were summarized as follows: - The DPB(Denitrifying Phosphorus removing Bacteria) performing denitrification and phosphorus uptake in the anoxic phase plays an important role in removing nitrogen and phosphorus in the BNR process activating soil microorganisms. - The PUR(Phosphorus Uptake Rate) of DPB in the anoxic phase was to be about 50% of PUR in the aerobic phase. - The DPB in the BNR process turned out to be increasing nutrient removal efficiency of BNR process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.45-48
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• 2003

The polishing mechanism of W-CMP process has been reported as the repeated process of passive layer formation by oxidizer and abrasion action by slurry abrasives. Thus, it is important to understand the effect of oxidizer on tungsten passivation layer in order to obtain higher removal rate (RR) and very low non-uniformity (NU%) during W-CMP process. In this paper, we investigated the effects of oxidizer on W-CMP process with three different kinds of oxidizers, such as $H_2O_2$, $Fe(NO_3)_3$, and $KIO_3$. In order to compare the removal rate and non-uniformity of three oxidizers, we used alumina-based slurry of pH 4. According to the CMP tests, three oxidizers showed different removal mechanism on tungsten surface. Also, the microstructures of surface layer by AFM image were greatly influenced by the slurry chemical, composition of oxidizers. The difference in removal rate and roughness of tungsten surface are believed to caused by modification in the mechanical behavior of $Al_2O_3$ abrasive particles in CMP slurry. Our stabilized slurries can be used a guideline and promising method for improved W-CMP process.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.837-847
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• 2000

For the treatment of wastewaters generated from beer industry and petrochemical company with high organic and nitrogen contents, laboratory scale of A/O Pure-Oxygen Biofilm (POB) process was developed and studied by means of the comparative economic analysis with extended aeration process. When the wastewater of beer company was initially treated by the A/O POB process in the ranges of 70 to 150 mg TOC/L diluted with tap water, higher than 92% of TOC removal was accomplished in the all ranges. In case of petrochemical wastewater, the initial TOC removal was as low as 52%, though, it increased to 86% after 32 days of operation and also the TKN removal marked 71% after 27 days. Continuous high removal rates were monitored in both the TOC and TKN parameters during the experimental period. Due to the cost for PSA (Pressure Swing Adsorption) setting and biomass supporting media installation, the initial construction cost of A/O POB process was 2.9 times higher than that of extended aeration process. However, the advantages such as low sludge production, no need for sludge recycling and low energy consumption allow the A/O POB process to have 2.5 times lower operation and maintenance costs. Consequently, in the long term of operation, it is likely that A/O POB process would show higher performance as well as cost effectiveness compared to extended aeration process.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.206-214
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• 2005

This study was initiated to evaluate efficiencies of suspenced-growth processes(CAS; Conventional Activated Sludge, MLE; Modified Ludzack-Ettinger) and hybrid process(Modified-Dephanox) on removal of organic matter(C), nitrogen(N) and phosphorus(P) in municipal wastewater. M-Dephanox process was designed to improve the performance of Dephanox process on denitrification efficiency. As the results, removal efficiencies of total chemical oxygen demand(TCOD), total nitrogen(T-N) and total phosphorus(T-P) in M-Dephanox process, which is hybrid process, were 12,3, 18.6 and 28.2% higher than those in MLE, which is suspended-growth process. The better removal efficiencies of TCOD, T-N and T-P in M-Dephanox than those in MLE result that M-Dephanox is not only hybrid or multi-sludge process but also process using biosorption mechanism which is possible to use organics in denitrification, effectively. Ammonia removal efficiency in nitrification reactor of M-Dephanox was 96.7% at short hydraulic retention time(HRT) of 2 hr which was 3 hr more short HRT than that(HRT 5 hr) reported in other related papers. This indicates that M-Dephanox process can reduce HRT of whole process.