• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.303-308
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• 2005

In this paper, the effects of oxidants on tungsten chemical mechanical polishing (CMP) process were investigated using three different oxidizers such as Fe(NO₃)₃, KIO₃ and H₂O₂. Moreover, the interaction between the tungsten film and the oxidizer was discussed by potentiodynamic polarization measurement with three different oxidizers, in order to compare the effects of W-CMP and electrochemical characteristics on the tungsten film as a function of oxidizer. As an experimental result, the tungsten removal rate reached a maximum at 5 wt％ Fe(NO₃)₃concentration, and when 5 wt％ H₂O₂was added in the slurry, the removal rate of W increased. Also, the microstructures of surface layer by atomic force microscopy(AFM) image were greatly influenced by the slurry chemical composition of oxidizers. It was shown that the surface roughness and removal rate of the polished surface were improved in Fe(NO₃)₃than KIO₃. The electrochemical results indicate that the corrosion current density of the 5 wt％ H₂O₂ and 5 wt％ H₂O/sub 2+/＋ 5 wt％ Fe(NO₃)₃was higher than the other oxidizers. Therefore, we conclude that the W-CMP characteristics are strongly dependent on the kinds of oxidizers and the amounts of oxidizer additive.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1181-1186
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• 2003

Chemical Mechanical Polishing (CMP) is an essential dielectric planarization in multilayer microelectronic device fabrication. In the CMP process, it is necessary to minimize the extent of surface defect formation while maintaining good planarity and optimal material removal rates. 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 W passivation layer, in order to obtain higher removal rate (RR) and very low non-uniformity (NU %) during W-CMP process. In this paper, we compared the effects of oxidizer or W-CMP process with three different kind of oxidizers with 5 wt% hydrogen peroxide such as Fe(NO$_3$)$_3$, H$_2$O$_2$, and KIO$_3$. The difference in removal rate and roughness of W in stable and unstable slurries are believed to caused by modification in the mechanical behavior of Al$_2$O$_3$ particles in presence of surfactant stabilizing the slurry.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.99-112
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• 1997

Mixing process of impinging jets of liquid oxidizer and liquid fuel is simulated by using water and sodium carbonate (Na$_{2}$CO$_{3}$) solution. The shapes of liquid sheets are visualized and flowrate distributions are measured by collecting droplets using measuring cells. Mixing charateristics are studied by using acid-base titration. Stable liquid sheets are formed and two liquid jets are well mixed for symmetric impinging jets. Similarity in flowrate distribution for various measuring heights is observed. For asymmetric impinging jets, liquid sheets become unstable as the difference in the velocities of jets increases. In some extreme cases, liquid sheets are not formed and the jets are separated. Dimensionless variables are adopted demonstrating similarly in flowrate distribution. Mixing characteristics vary significantly with experiment conditions.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.163-166
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• 2000

Hydrogen sulfide, ammonia and benzene which are generated from natural leather industry were simultaneously removed using biofilter including benzene degrading microbial consortia and sulfur oxidizer Thiobacillus sp.IW. The removal efficiency of benzene was maintained 90% in average for single and mixed gas treatment and that of ammonia was 99%, whereas at of hydrogen sulfide was relatively lower 85%.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.153-157
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• 2003

Supersonic and hypersonic aircrafts must pass wide range of speed to reach high speed region. But for existing engines the most efficient operating speed ranges are decided according to their flying speed, so an engine which mixes several engines like TRJ (Turbo Ramjet) and ARJ (Air Turbo Ramjet) has been planed. This mixed type engine has inefficiency that more than two engines must be installed simultaneously, but the pulse detonation engine (PDE) that uses detonation wave has a strong point that it can operate in all speed range with single engine. This paper deals with the simulation of the pulse detonation engine which uses hydrogen peroxide $(H_2O_2)$ mono propellant. Hydrogen peroxide is low-cost propellant, and it is reacted without oxidizer. Comparison between $H_2-O_2$ mixture with $H_2O_2$ mono propellant about thrust, pressure, temperature and velocity shows that $H_2O_2$ is a very useful propellant.

• Journal of the Korean Society of Combustion
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• v.22 no.3
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• pp.23-28
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• 2017

The fuel and oxidizer mixing process in the shock tube driven section is simulated numerically. The boundary condition is set based on an shock tube experimental condition. The objective is to predict the gas mixing time for experiments. In the experiment, the amount of fuel to be injected is determined in advance. Then, according to duration of fuel injection, 5 cases with the same fuel mass but different fuel mass flow rate are simulated. After fuel is injected into the driven section, the fuel and air will be mixed with each other through convection and diffusion processes. The mixing time is predicted numerically for experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.9-15
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• 2012

As a propellant of a high speed underwater vehicle, the hydro-reactive solid metal particles using seawater as a oxidizer maximizes its specific impulse when the solid metal particles and the seawater are uniformly mixed in the combustion chamber. The purpose of this study is to investigate the effects of injector geometry on the particle distribution of similarity point of view. For the purpose of this similarity of the mean velocity and particle number density along the radial direction was measured by Particle Image Velocimetry(PIV).

• Transactions on Electrical and Electronic Materials
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• v.7 no.3
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• pp.108-111
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• 2006

The oxidizer-induced corrosion state and microstructure of surface passive metal-oxide layer greatly influenced on the removal rate of tungsten film according to the slurry chemical composition of different mixed oxidizers. In this paper, the actual polishing mechanism and pH-potential equilibrium diagram obtained from potentiodynamic polarization curve were electrochemically compared. An electrochemical corrosion effect implies that slurries with the highest removal rate (RR) have the high dissolution rate.

• Journal of the Korean Society of Fashion and Beauty
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• v.2 no.3 s.3
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• pp.68-73
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• 2004

The purpose of this study was to review the changes of hair colors by means of powder decolorant and oxidizers. For this purpose, a questionnaire survey on uses of powder decolorant and oxidizers was conducted, and the collected data thereby were analyzed. This study was concluded as follows; First, it was confirmed that when the hydrogen peroxide was used alone, the hair color was not changed however its concentration was high. Second, when powder decolorant and hydrogen peroxide were mixed at the ratio of 1:2, it was found that the higher the concentration of hydrogen peroxide was, hair color was changed more. Third, it was confirmed that the hair color became brighter when hairs were decolored three times serially. Fourth, it was found that hairs became tougher when the concentration of hydrogen peroxide was higher and when hairs were decolored many times serially.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.138-144
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• 2005

This study was carried out to investigate the changes of nitrifying bacterial populations including Nitrosomonas sp. and Nitrobacter sp. in $A^2/O$ pilot plant with the configuration of anaerobic-anoxic-oxic reactors. The suspended nitrifying bacterial populations in mixed liquor and those of attached populations on granular carrier surface made by molded waste tire were analyzed by Fluorescent in situ Hybridization(FISH) method. The nitrification rate of a pilot plant showed the value of $1.97{\sim}2.98\;mg\;N/g$ MLVSS hr. The ratios of suspended ammonia oxidizer including Nitrosomonas sp. (NSO) to total bacteria in each reactor were oxic < anoxic < anaerobic. On the contrary, the ratios of suspended nitrite oxidizer including Nitrobacter sp. (NIT) were anaerobic < anoxic < oxic. The thickness, dry density and mass of the attached biomass on granular carriers were $180{\sim}188\;{\mu}m$, $38.5{\sim}43.9\;mg/cm^3$, $29.4{\sim}32.5\;mg/g$, respectively. Also, the ratios of attached nitrifier to total bacteria on granular carriers were similar regardless of ammonia/nitrite-oxidizer (NSO; 3.2%, NIT; 2.8%) and very low compared to those(NSO; $22.8{\sim}28.4%$, NIT; $17{\sim}26%$) of suspended nitrifier.