• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.281-287
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• 1991

This study was designed to investigate the influence of the clasp arm length on the change of retentive force with repeated placement or removal. The author measured the retentive force of Akers clasp and I-bar clasp in the depth of undercut 0.5mm, 0.25mm, respectively, varying the length of clasp arm, that is, 10mm, 14mm, 17mm in Akers clasp and 16mm, 18mm, 20mm in I-bar clasp. The retentive force was measured just before the placement of removal, after 100 times repeated placement or removal, after 300 times repeated placement or removal. The obtained results were as follows : 1. The shorter the clasp arm, the greater retention in Akers clasp and I-bar clasp(p<0.05). 2. There was decreased retentive force of Akers clasp and I-bar clasp after 300 times repeated placement or removal(p.<0.005). 3. The decreasing rate of retentive force in Akers clasp with 10mm was higher than that with 17mm, after 300 times repeated placement or removal, but there was no statistica difference(p>0.05).

• Journal of Environmental Science International
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• v.8 no.4
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• pp.443-449
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• 1999

This paper describe the working of algal culture system under batch and continuous feeding effluents in biological treatment process. The main objective of this study was the determination of fundamental opeating parameters such as dilution rates, light intensity, biomass concentration, nutrients contents, which engender an effective nutrient and organic waste removal process. The results of this research indicate that the algae system will remove effectively nutrient and organic waste. In batch cultures, 91.8% dissolved orthophosphate and 83.3% ammonia nitrogen were removed from the sewage in ten days. In continuous flow systems, a detention time of 2.5 days was found adequate to remove 91% T-P, 87% T-N and 95% $NH_3-N$. At 22-28$^{\circ}C$, 60 rpm, with an intensity of 3500 Lux, the specific growth rate, k was 0.59/day in batch experiments. The optimal growth temperature and nutrients rate (N/P) were respectively $25^{\circ}C$ and 3~5. With an abundant supply of untrients, it was possible to sustain substantial population densities in the temperature range of 22~28$^{\circ}C$.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.24-30
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• 1999

A biological filter for treatment of toluene among volatile organic compounds was studied. The investigation was conducted using specially built stainless steel columns packed with granular activated carbon and cold for removal of toluene. The G.A. and mold as filter material was also coated with Pseudomonas putida microorganisms.The biofilter unit was operated in the condition of moisture content vairation at gas loading rate of 12.5 l/min. Gaseous toluene taken from tedlar bag was analyzed by the use of G.C equipped with F.I.d detector. The removal efficiency of gaseous toluene was 95% at average inlet concentration of 950 ppm during bio-degradation operating condition. Effective removal efficiency was obtained with moisture content 27.5% at activated carbon and 32% at mold in this study. The effective operating condition were obtained with pH 6-8, temperature 28-42℃ for microbial degradation at gas loading rate of 12.5 l/min in packed material.

• Journal of Environmental Health Sciences
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• v.22 no.1
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• pp.99-106
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• 1996

The purpose of this study is to observe a specific removal efficiency of synthethetic wastewater which is managed by upflow submerged type at porous media which was sinteringed on a comparative low temperature 600$\circ$C, was annexed slag and humus soil with main material kaolinite. Observing removal efficiency quality of each media, a mixed media of kaolinite and humus soil by gravity percent 60, 40% respectively showed the most excellent removal utility, and applied predictive models for suspended culture kinetics without consideration diffusion limitation, and when analyzed kinetic which had been processed by this study the removal efficiency accompanied by carbon, nitrogen, phosphorous volumetric loading rate variation standed for a comparative large change rate 61~71%, it means the selection of the most proper load factor had a great effect on the highly removal efficiency, yield coefficient(Y) and specific microbial attach equation showed 1.53 mgVSS/mgCOD, $m_p=10039.4\times ((S_0)/(6.75+S_0))$ repectively.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.703-709
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• 2013

Among many microalgae cultivation types, heterotrophic culture with low cost carbon sources and energy saving culture method is crucial. A result of estimating the effects of pH on wastewater treatment using heterotrophic growing microalgae Chlorella sorokiniana shows that there was no difference in microalgae growth amount and nitrogen, phosphorus removal rate by wide range of pH(5 ~ 9). From pH 5 to 9, total nitrogen, phosphorous and glucose removal rates were 10.5 mg-N/L/d, 2 mg-P/L/d, 800 ~ 1000 mg/L respectively. This study reveals that C. sorokiniana cannot metabolite glycerol heterotrophically, however, glucose and acetate were proper carbon sources for growth and T-N, T-P and TOC removal. This research highlights the potential of heterotrophic microalgal growth with wastewater treatment plant with wide range of pH and carbon sources.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.291-301
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• 2002

In this study, nutrients treatment by sequencing batch reactors(SBR) was performed. Nitrogen and phosphorus removal efficiencies were evaluated by changing SRT and mixing/aeration ratio. Not only nitrogen but also phosphorus removal patterns were investigated through track studies on 1 cycle. As SRT was fixed and mixing/aeration ratio was changed, maximum nitrogen removal efficiency was 87.6% at mixing/aeration ratio 0.67. Phosphorus removal efficiencies were more than 85.5% except no mixing condition. As mixing/aeration ratio was fixed and SRT was changed, nitrogen removal efficiencies were 70.5~79.8%, which represented slight changes, while phosphorus removal efficiencies were 49.0~97.3%, which represented sharply decreasing tendency at less than 20 day. Both phosphorus release rate k and maximum phosphorus release rate $P_{max}/M$ were are decreased as SRT was decreased, but they were not affected by mixing/aeration ratio. It was found that there is a linear relationship between ortho-phosphate uptake and maximum ortho-phosphate release.

• Environmental Engineering Research
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• v.23 no.1
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• pp.114-119
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• 2018

Yarn dyed wastewater has to be treated prior to disposal into the water bodies due to its high content of harmful organic compounds. In this study, the performance of Chemical Oxygen Demand (COD) removal and kinetic rate constant are investigated via hybrid electrocoagulation-Fenton in a continuous system using wastewater discharged from a yarn dyed industry in Surabaya city. The wastewater was treated in a batch mode using electrocoagulation to reduce Total Suspended Solid, followed by Fenton method in a continuous system to reduce COD level. Various Fe(II) feeding modes, molar ratio of $Fe(II)/H_2O_2$, initial pH of wastewater, and flow rate are used in this study. The results show that COD removal process obeys a pseudo-first order kinetics. At $Fe(II)/H_2O_2$ ratio of 1:10, initial wastewater pH of 3.0, and feed flow rate of 30 mL/min, the COD removal efficiency was observed to be 80%, and the kinetic rate constant is $0.07046min^{-1}$. The chemical cost for the treatment estimated to be IDR 160 per L wastewater, which is cheaper than the previously reported batch system of IDR 256/L.

• Transactions on Electrical and Electronic Materials
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• v.8 no.2
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• pp.53-57
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• 2007

In this study, a novel slurry containing ceria as the abrasive particles was analyzed in terms of its frictional, thermal and kinetic attributes for interlayer dielectric (ILD) CMP application. The novel slurry was used to polish 200-mm blanket ILD wafers on an $IC1000_{TM}$ K-groove pad with in-situ conditioning. Polishing pressures ranged from 1 to 5 PSI and the sliding velocity ranged from 0.5 to 1.5 m/s. Shear force and pad temperature were measured in real time during the polishing process. The frictional analysis indicated that boundary lubrication was the dominant tribological mechanism. The measured average pad leading edge temperature increased from 26.4 to $38.4\;^{\circ}C$ with the increase in polishing power. The ILD removal rate also increased with the polishing power, ranging from 400 to 4000 A/min. The ILD removal rate deviated from Prestonian behavior at the highest $p{\times}V$ polishing condition and exhibited a strong correlation with the measured average pad leading edge temperature. A modified two-step Langmuir-Hinshelwood kinetic model was used to simulate the ILD removal rate. In this model, transient flash heating temperature is assumed to dominate the chemical reaction temperature. The model successfully captured the variable removal rate behavior at the highest $p{\times}V$ polishing condition and indicates that the polishing process was mechanical limited in the low $p{\times}V$ polishing region and became chemically and mechanically balanced with increasing polishing power.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.264-267
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• 2004

Recently the pulsed power systems have been widely used in many fields such as E/P(Electrostatic Precipitator), DeNOx/DeSOx power systems, ozone generators and power sources of the laser beam. In this paper, we studied various electrical characteristics for arc suppression of line-to-line electrodes in air and removal of the metaloxide using our pulsed power system. To obtain high efficiency of the pulsed power system, we repeatedly experimented and tested their characteristics. by adjusting electrode length of the load. As a result, when the value of the electrode length and pulse repetition rate were changed at the load, the value of the arc voltage changed at the electrode load. In conclusion, we controlled arc voltage of the load by ,changing electrode length and pulse repetition rate. Also. we stydied removal area of the metaloxide using area discharge according to pulse repetition rate.

• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.348-355
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• 2007

We investigated temporal changes of composition, habitat area, growth rate and elements content of hydrophytes at the artificial vegetation island (AVI) in Kyungan Stream within Lake Paldang. We also assessed nutrient removal rate through cutting off the emergent part of hydrophytes. The kinds of hydrophytes have increased from four species (P. australis, P. japonica, T. angustifolia and the Z. latifolia) at initial stage of installation to more than 29 species for 6-year operation. P. japonica was most dominant species at the AVI in 2006. The habitat area of have increased about 2.5 times compared to the initial planting area, occupying 63% of AVI's vegetation area. The incoming species of S. fluviatilis and B. frondosa have adapted successively and expanded habitat area in the AVI. The relative growth rate of P. japonica and P. australis was highest in spring sprouting period. Their hights and weights have increased until summer, by the time they were cutting off the emergent part. They started regrowth immediately after cutting and continued to grow until September and withered away in November. The carbon contents of P. japonica and P. australis have increased during growth phase, on the contrary, the nitrogen and phosphorus contents have decreased. By cutting off and removing the emergent part (leaves and branches) of hydrophytes twice from AVI, $17.6gN/m^2/y$ of nitrogen and $1.3gP/m^2/y$ of phosphorus was removed from AVI in 2006.