• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.3
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• pp.32-37
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• 2002

The paper mill wastewater actually generating bulking was used to apply to the spot. Batch and continuous type pilots were used in this study. Optimal time after propagating generation of activated sludge in aeration basin by adding Hoc forming microorganism was 24 and 36hours while optimal time of activated sludge in original aeration basin was 60hours. Showing the difference of sedimentation velocity at 7th day after operating a pilot continuously, SV30 was decreased to 50% at 13th day. COD value in aeration basin with floe forming microorganism was 35mg/L while COD value in original aeration basin was 52mg/L. It was indicated that application of Hoc forming microorganism can control the bulking of paper mill wastewater by shortening of recovery time and improving of pollution removal efficiency.

• 연구논문집
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• s.30
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• pp.67-77
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• 2000

This study was performed to investigate the characteristics and performance of model Decanter for separating swine wastewater to solid and liquid which is slurry state with 12.6% TS. Swine wastewater of the slurry tank was pumped into model Decanter which capacity was $2m^3$/hr in 10% TS Slurry inside of bowl was separated to solid-liquid by centrifugal acceleration. Sampling was done in the section of slurry feed pipe, supernatant outflow pipe, cake discharge pipe. After solid-liquid separation TS, $COD_cr$ and slurry volume reduction effect represented 38%, 40%, 19.6% respectively. Relation factor of model Decanter operation slurry concentration, optimum retention time of slurry, overflow velocity of supernatant, supernatant concentration, sludge removal rate etc. Optimal operation conditions can be set and evaluated efficiency based on the experimental results in the case of Decanter adopted for solid-liquid separation in highly concentrated swine wastewater.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.103-104
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• 2006

$Pb(Zr,Ti)O_3(PZT)$ is very attractive ferroelectric materials for ferroelectric random access memory (FeRAM) applications because of its high polarization ability and low process temperature. However, Chemical Mechanical Polishing (CMP) pressure and velocity must be carefully adjusted because FeRAM shrinks to high density devices. The contaminations such as slurry residues due to the absence of the exclusive cleaning chemicals are enough to influence on the degradation of PZT thin film capacitors. The surface characteristics of PZT thin film were investigated by the change of process parameters and the cleaning process. Both the low CMP pressure and the cleaning process must be employed, even if the removal rate and the yield were decreased, to reduce the fatigue of PZT thin film capacitors fabricated by damascene process. Like this, fatigue characteristics were partially controlled by the regulation of the CMP process parameters in PZT damascene process. And the exclusive cleaning chemicals for PZT thin films were developed in this work.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.15-20
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• 1999

In this study, the effects of the maximum grit depth of cut on the grinding characteristics were investigated. And AE signals produced during grinding processes have been studied to find out the appropriate AE parameters for assessing grinding processes. S45C steel has been ground under the conditions yielding removal rate of workpiece, 100, 200, 300 and 400rnm$^3$/min which was achived by altering workpiece velocity($\upsilon$) and apparent depth of cut(Z). According to the experimental results, the value of surface roughness increases but grinding power, energy rate of AE signal(AErms$^2$) and specific grinding energy consumed decrease with increase of the maximum grit depth of cut.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2390-2395
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• 2008

The water droplet motion in an air flow microchannel with pores through which water emerges is studied numerically by solving the equations governing the conservation of mass and momentum. The gas-liquid interface is tracked by a level set method which is based on a sharp-interface representation for accurately imposing the matching conditions at the interface and is modified to implement the contact angle conditions on the wall and pores. The numerical results show that the droplet growth and detachment pattern depend significantly on the contact angle and inlet air velocity. Also, the dynamic interaction between the droplets growing on multiple pores is investigated. The pore arrangement subject to droplet merging is found to be not effective for water removal.

• Journal of Environmental Science International
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• v.29 no.3
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• pp.299-306
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• 2020

This study analyzed the changes in the concentrations of the pollutants of constructed treatment wetlands which come from the discharge water of a sewage treatment plant. According to the results of budgets in constructed wetlands, the net production of the organic carbon, nitrogen and phosphorus were 368 kgC/month, 306 kgN/month and -49 kgP/month, respectively. The high particle form of pollutants are mostly removed due to settlement and absorption when passing through wetlands, but because a low processing efficiency for pollutants was shown when sewage treatment plant wastewater flows in, there is a need for a water management system that can reduce the organic matter load through monitoring. The low removal efficiency of constructed wetlands were caused by both structural and operational problems. Therefore, to enable to play a role as a reduction facility of pollutants, an appropriate design and operation manuals for constructed wetlands is urgently needed.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.290-291
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• 2001

The relationship between velocity, viscosity, diffusion coefficient, mass transfer coefficient and characteristic length and mass transfer data can be correlated by dimensionless relationship in electrolytic process. The performance of dyestuff removal was decreased as the flow rate of electrolyte was increased. It was due to the effect of retention time decreasing was superior to that of turbulent inlet mixing. Sh/Sc$\^$1/3/ vs Re plot for Al flat electrode did not showed the general tendency of the relationship between Sh/Sc$\^$1/3/ and Re. It can be thought that flow rate was not sufficiently high to increase the effect of mixing.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.588-590
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• 2003

For the normal operations, KOMPSAT-1 orbits are determined using GPS navigation solutions data such as position and velocity vectors. Currently, the accuracy of GPS navigation solution data is generally known as on the order of 10~30 m with the removal of S/A. In this paper, an estimate of the current orbit determination accuracy for the KOMPSAT-1 is given. For the evaluation of orbit determination accuracy, the orbit overlap comparison is used since no independent orbits of comparable accuracy are available for comparison. As a result, It is shown that the orbit accuracy is on the order of 5 m RMS with 4 hrs arc overlap for the 30 hr arc.

• Journal of the Korean Society of Visualization
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• v.22 no.2
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• pp.90-95
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• 2024

This study examined changes in airway airflow characteristics before and after extensive surgery for tongue cancer, which includes neck dissection and reconstruction. Pre- and post-operative CBCT scans were used to model 3D upper airways. Computational fluid dynamics (CFD) simulations analyzed airflow and pressure variations. Results showed a significant reduction in airway volume post-surgery, especially in the posterior tongue and epiglottis areas, leading to increased airflow velocity and complex vortex formations. Pressure drop analysis revealed that post-surgery, higher negative pressure is required for inhalation, indicating increased breathing effort. This suggests that the surgical removal of cancerous tissues and lymph nodes, along with reconstruction, alters airway geometry significantly, potentially impacting respiratory function. The findings highlight the clinical importance of assessing airway changes in tongue cancer surgery to anticipate and mitigate postoperative respiratory complications.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.836-842
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• 1994

The optimum design conditions of gas sparger pipe and the effects of operating variables on $SO_2$ removal efficiency have been examined in Jet Bubbling Reactor. Geometry of gas sparser pipe of Jet Bubbling Reactor is a very important factor to obtain a effective gas-liquid contact. Test results revealed that Reynolds numbers at sparger and slot have to be kept greater than 12,000 identically at a given gas velocity. $SO_2$ removal efficiency was a function of ${\Delta}P$, pH, inlet $SO_2$ concentration and particle size of limestone and was more sensitive to the change of ${\Delta}P$ than to the changes of others. The ${\Delta}P$ of at least 230mmAq must be maintained to acheive the above 90% $SO_2$ removal at pH of 4.0 which is considered as adequate operating pH. Higher $SO_2$ removal efficiency was obtained even at lower pH ranges, which resulted from the complete oxidation of the absorbed $SO_2$ to sulfates by adding air and consequently from the reduction of $SO_2$ equillibrium partial pressure in the gas-liquid interface The 99.5% of the limestone utilization was attained in pH range from 3.0 to 5.0 with regardless to the particle size of limestone employed.