• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.407-411
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• 2003

The purpose of this paper is to study the removal of nitrogen oxide(NOx) using a wire-plate type plasma reactor with magnet attached for indoor air purification. In order to produce a more effective reactor, we conducted magnetic field simulations. The results of the magnetic field simulations show that NOx can be removed more effectively. The results from the magnetic field simulation show that when 7 magnets were applied to the reactor, the magnetic flux density was at its highest amount than when using 0, 3, or 5 magnets. From the data obtained by the simulation results a plasma reactor was made and thus, several experiments were conducted. The best removal efficiency was obtained with 14 W AC power to the reactor with 5 magnets.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.379-384
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• 2005

In this research, coagulation was employed as the pretreatment for membrane process. The effective coagulation conditions were decided after the discussion of different coagulant doses and mixing conditions, etc. Raw water was taken from Nakdong River. The best operation occurred when G value was $230s^{-1}$ and the slow mixing lasted around 5 minutes at G value was $23s^{-1}$. To investigate the optimum coagulant dosage, the optimum organics removal was target as organic removal reduces membrane fouling effectively than particle removal. This result indicated that organics are more important causes than turbidity for membrane fouling. However, turbidity becomes an important factor after certain amount of organic matters is removed.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.34-40
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• 1999

Aerobic night-soil treatment effluent containing high concentration of ammonia nitrogen was treated to remove nitrogen using Bardenpho process with Methanol addition. The objective of this study was to investigate the feasibility of complete nitrogen removal at three different HRTs such as 6.25d, 5d, and 3.75d, respectively. At each HRT, the nitrogen removal efficiencies are 92%, 99% and 97% and the required amount of methanol are 3.05gMeOH/gN, 2.75gMeOH/gN, and 3.38gMeOH/gN, respectively. Specific nitrification rates are decreased proportional to HRT and are $0.022gNH_4^+-N/g\;MLVSS{\cdot}day$, $0.0332gNH_4^+-N/g\;MLVSS{\cdot}day$ and $0.051gNH_4^+-N/g\;MLVSS{\cdot}day$ and specific denitification rate are decreased proportional to HRT and are $0.0210g\;N/gMLVSS{\cdot}day$, $0.0330g\;N/gMLVSS{\cdot}day$ and $0.0525g\;N/gMLVSS{\cdot}day$, respectively.

• Journal of Microbiology and Biotechnology
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• v.8 no.3
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• pp.222-228
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• 1998

The characteristics of cometabolic removal of xylenes by Alcaligenes xylosoxidans Y234 were investigated. m-Xylene was found to be degraded while ο- and p-xylene were biotransformed into cresols in the presence of benzene or toluene. A lower level of benzene was required than that of toluene to remove the same amount of xylenes, which suggested benzene was a more effective primary substrate than toluene. ο-Xylene was found to be the most toxic to Alcaligenes xylosoxidans Y234 followed by p-xylene and m-xylene. Rates of cell decay during cometabolic removal of ο-, m-, or p-xylene were decreased by up to $76\%$ when benzene-adapted cells were inoculated. Xylenes were removed efficiently using benzene-adapted cells.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.100-105
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• 1999

This work analyses the effects of electrical conductivities of dielectric and cobalt amount on output parameters such as metal removal rate and the surface roughness value of cemented carbides cut by wire electrical discharge machining(W-EDM). Especially, the cracking behaviour of W-EDM machined surface and optimal machining condition of three kinds of cemented carbides, which have different chemical composition of tungsten carbide and cobalt are also tested. Experimental result shows that increases in cobalt content and electrical conductivity of the dielectric affect the metal removal rate and substantially worsen the final surface quality as a greater quantity of solidified metal deposits on the eroded surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.211-213
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• 1999

In this paper, we documented the controlling oxide removal amount on the pattern wafer using removal rate and removal thickness of blanket wafer. There was the strong correlation relationship for both(correlation factor:0.7109). So, we could confirm the repeatability as applying for STI CMP process from the obtained linear formular. As the result of repeatability test, the difference of calculated polishing time and actual polishing time was 3.48 seconds based on total 50 lots. If this time is converted into the thickness, it is from 104$\AA$ to 167$\AA$. It is possible to be ignored because it is under the process margin.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.552-552
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• 2003

The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments and a hand instrument were used to remove these materials. Forty extracted mandibular premolars were prepared by step-back method and obturated with gutta-percha and sealer. Gutta-percha removal for group 1 was done using hand file with chloroform, group 2 using Profile and group 4 using K3. The following factors were evaluated : Time taken to reach working length, total time for gutta-percha removal and number of fractured instruments.(중략)

• Progress in Superconductivity and Cryogenics
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• v.21 no.2
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• pp.26-30
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• 2019

Coal is the most abundant fossil fuel on Earth and is used in a wide range of applications. The direct combustion of high-sulfur coal produces a large amount of sulfur dioxide, which is a toxic and corrosive gas. A new superconducting high gradient magnetic separation (HGMS) technology was studied to remove sulfur from high sulfur coal. The magnetic separation concentrate was obtained under the optimum parameters, such as a particle size of -200 mesh, a magnetic field strength of 2.0 T, a slurry concentration of 15 g/L, and a slurry flow rate of 600 ml/min. The removal rate of sulfur is up to 59.9%. The method uses a magnetic field to remove sulfur-containing magnetic material from a pulverized coal solution. It is simple process with, high efficiency, and is a new way.

• Environmental Engineering Research
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• v.17 no.3
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• pp.133-138
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• 2012

Polyvinyl alcohol/alginate hydrogel beads containing Mg-Al layered double hydroxide (LDH-PVA/alginate beads) were synthesized for phosphate removal. Results showed that blending PVA with the LDH-alginate beads significantly improved their stability in a phosphate solution. The kinetic reaction in LDH-PVA/alginate beads reached equilibrium at 12 hr-post reaction with 99.2% removal. The amount of phosphate removed at equilibrium ($q_e$) was determined to be 0.389 mgP/g. The equilibrium data were described well by the Freundlich isotherm with the distribution coefficient ($K_F$, 0.638) and the constant (n, 0.396). Phosphate removal in LDH-PVA/alginate beads was not sensitive to solution pH. Also, the removal capacity of LDH-PVA/alginate beads ($q_e$, 1.543 mgP/g) was two orders of magnitude greater than that of PVA/alginate beads ($q_e$, 0.016 mgP/g) in column experiments. This study demonstrates that LDH-PVA/alginate beads with a higher chemical stability against phosphate compared to LDH-alginate beads have the potential for phosphate removal as adsorptive media.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.259-266
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• 2011

Project owner, asbestos removal specialist, experts on asbestos removal work, as counter parts to be defined in the study to make out research goals have been asked with questionnaire survey and replied with 65, 275, 32 cases, respectively. And additionally, direct interview 73 sheets have been collected to find out current status of required engineers and equipments assigned and provided to the field, from them, three(3) concerned parties. Questionnaire subjects are composed of common items, reasonable unit cost, need of separate contract-awarding system, status of performing standard contract, status of providing legal engineers and equipments. Concentrated review of two~three questions by subject has been made to find out and compare idea results between three(3) concerned parties. First, legal and practical work status survey have been made to determine reasonability of introducing separate contract-awarding system, as a part of ensuring reasonable unit work cost. And then, two different status have been compared and there is introduction possibility of separate contract-awarding system, it is found out. The possibility of separate contract also has been confirmed by comparison of domestic legal grounds. Justificating grounds to introduce separate contract-awarding system have been shown. Standard contract status between asbestos removal specialists has been compared using two cases of providing removal work contract and receiving it. It is shown that case of 50 percent or less contains 38.5% when they receive contract, but only 10 percent reduction of original contract amount has been made when they provide it. It means that asbestos removal specialists do not keep occupational safety and health regulations.