• Journal of the Korean Institute of Gas
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• v.23 no.3
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• pp.20-26
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• 2019

Selective catalytic reduction(SCR) method is widely used among various methods for reducing nitrogen oxides in combustion devices of coal power plant. In the present study, the computational fluid dynamic analysis was accomplished to derive the optimal shape of ammonia-dilution air mixing device in a ammonia injection grid. The distribution characteristics of flow and $NH_3$ concentration had been elucidated for the reference shape of ammonia mixing device(Case 1). In the mixing device of Case 1, it could be seen that $NH_3$ distribution was shifted to the wall opposite to the inlet of the ammonia injection pipe. For the improvement of $NH_3$ distribution, the case(Case 2) with closing one upper injection hole and 4 side injection holes, the case(Case 3) with installing horizontal plate at the upper of ammonia injection pipe, the case(Case 4) with installing horizontal plate and horizontal arc plate at he upper of ammonia injection pipe were investigated by analyzing flow and $NH_3$ concentration distributions. From the present study, it was found that the % RMS of $NH_3$ for Case 4 was 4.92%, which was the smallest value among four cases, and the range of $R_{NH3}$ also has the optimally uniform distribution, -10.82~8.34%.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.253-262
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• 2012

With the aim of remediating soils contaminated by heavy metals and oil, experimental research was conducted to evaluate the optimal design factors for remediation in terms of efficient soil washing methods and processes. The experiments employed absorptiometric analysis and gas chromatography methods to reduce the concentration of heavy metals such as cooper (Cu), lead (Pb), and zinc (Zn), and total petroleum hydrocarbons (TPH) in contaminated soils. The experimental processes consisted of deciding on the washing solution, washing time, and dilution ratio for contaminated soils. A dissolution analysis of heavy metals was then performed by the addition of surfactant, based on the results of the decision experiments, and the injection processes of microbes and hydrogen peroxide were selected. The experimental results revealed that reduction effects in contaminated soils under the experimental conditions were most efficient with hydrochloric acid 0.1 mole, washing time 1 hour, and dilution ratio 1:3, individually. Additional reduction effects for heavy metals and TPH were found with the addition of a washing solution of 1% of surfactant. The addition of microbes and hydrogen peroxide caused a reduction in TPH concentration.

• KSBB Journal
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• v.24 no.5
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• pp.432-438
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• 2009

Here, we demonstrated simple nucleic acid, RNA, concentration method using polymer micro chip containing glass bead ($100\;{\mu}m$). Polymer micro chip was fabricated by PDMS ($1.5\;cm\;{\times}\;1.5\;cm$, $100\;{\mu}m$ in the height) including pillar structure ($160\;{\mu}m\;(I)\;{\times}\;80\;{\mu}m\;(w)\;{\times}\;100\;{\mu}m\;(h)$, gap size $50\;{\mu}m$) for blocking micro bead. RNA could be adsorbed on micro glass bead at low pH by hydrogen bonding whereas RNA was released at high pH by electrostatic force between silica surface and RNA. Amount of glass beads and flow rate were optimized in aspects of adsorption and desorption of RNA. Adsorption and desorption rate was measured with real time PCR. This concentrated RNA was applied to amplification micro chip in which NASBA (Nucleic Acid Sequence Based Amplification) was performed. As a result, E.coli O157 : H7 in the concentration of 10 c.f.u./10 mL was successfully detected by these serial processes (concentration and amplification) with polymer micro chips. It implies this simple concentration method using polymer micro chip can be directly applied to ultra sensitive method to measure viable bacteria and virus in clinical samples as well as environmental samples.

• Journal of Aquaculture
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• v.7 no.3
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• pp.177-187
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• 1994

The objective of the present study were to evaluate nitrification characteristics and determine optimum treatment conditions of three phase fluidized bed reactor for recycling water treatment of aquaculture. When the loading rates were 2.739-0.086kg $COD/m^3/day$ and 1.575-0.128kg $NH_4\;^+-N/m^3/day$, COD and ammonia removal efficiencies were $56.3-94.7\%\;and\; 67.3­92.6\%$, respectively. The maximum removal rates of COD and ammonia were 1200mg/l/day and 488mg/l/day, respectively. Ammonia removal rates were more than $90\%$ beyond 1hr HRT. The ammoniaremoval efficiency was sensitive to the variation of media concentration and air flowrate.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.25-31
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• 2010

네덜란드 브리젠빈 하폐수처리장 최종방류수의 $NH_4$-N 및 TN(Total Nitrogen)농도를 방류수 수질기준인 각각 4 mg/L와 10 mg/L에 맞추기 위한 최적의 운전조건을 도출하기 위해 다양한 제어시스템이 시뮬레이션 되었다. 본 연구에 사용된 모델은 IWA(International Water Association) 활성슬러지 모델 No.1 (ASM No.1)이었고, GPS-X가 시뮬레이터로 사용되었다. 모델링을 위한 매개변수 민감도 분석결과 ASM No.1의 총 19개 매개변수 중 8개 변수 ($Y_H$, ksh, koh, $b_H$, ${\mu}_a$, $k_{NA}$, kh, ka)가 방류수 수질에 영향을 미치는 것으로 조사되었고 이들 매개변수에 대해 보정을 수행하여 사용하였다. SRT, 호기/무산소기간, 외부탄소원 주입시간 변화에 따른 방류수질 변화를 시뮬레이션하였는데, 호기/무산소 11h/1h인 조건에서 SRT가 20일에서 25일로 증가되면 $NH_4$-N가 5.0 mg/L에서 2.9 mg/L로 감소되었고 호기/무산소 2h/1h의 조건에서는 SRT증가에 따라 $NH_4$-N은 큰 감소를 보이지만, 바이패스되는 유입수량의 감소로 탈질율이 낮아 방류수 TN이 11.1~11.5 mg/L로 예측되는 결과가 도출되었다. 탈질율을 높이기 위한 아세트산 주입은 동일한 양의 아세트산을 무산소 전기간 (1h)동안 균일 주입하는 것 보다는 무산소 초기 15분내에 주입하는 것이 효율적인 것으로 나타났다.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1552-1554
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• 2002

본 논문에서는 실리콘을 기초로 한 포토다이오드를 제작하여 현재 바이오센서에서 이용되고 있는 luminol 화학 발광을 전기적으로 검출하였다. 우선, 실리콘 웨이퍼에 이온주입을 통해 p-n 접합을 형성하고 Al 전극을 형성시켜 포토다이오드를 제작하였다. PDMS을 passivation 막으로 사용하여 horseradish peroxidase(HRP) 농도 변화에 따른 발광의 최적조건과 luminol, HRP가 섞인 용액에 서로 다른 양의 과산화수소를 넣어 발광이 최대로 발생하는 혼합비를 측정하였다. 최종적으로 2mM luminol, 25U HRP 조건 하에서 과산화수소 농도에 따른 화학 발광을 측정하였으며, $10{\mu}M$부터 $500{\mu}M$ 범위의 과산화수소 농도 변화에 따른 포토다이오드의 감도는 단위 면적당 23.429pA/ ${\mu}M$이다.

• KSBB Journal
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• v.14 no.2
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• pp.160-166
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• 1999

High cell density cultivation of microalga Dunaliella bardawil using nitrogen fed-batch cultures was studied in batch flask. Optimum environmental conditions include concentrated nutrients except NaCl and carbon sources, carbon sources, pH, light, agitation, nitrate and phosphate ions. Cell growth, consumption rates of nitrate and phosphate ions were monitored. Optimal conditions for higher cell density were found to be(in the range tested): 5 times concentrated media(1 times-10 times concentrated media) pH 8.0 (7.0-9.0) white light(blue and red light) 15mM of nitrate (0.94-15mM) 250mM $NaHCO_3$ and $CO_2$ gas. However, the addition of phosphate ions did not enhance the algal maximum cell density and specific growth rate. Nitrate was found to be effective for the cell growth. The maximum cell density of fed-batch culture using nitrate ions in $8.955{\times}106$cells/ml after 189hr incubation.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.49-55
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• 2010

The oil spill occurred frequently due to probably the increased consumption of oil as the energy source and the raw materials of various chemicals. For the treatment of oil contaminated groundwater, DAF(Dissolved Air Flotation) is being used but the removal efficiency is low. Therefore it is necessary to reduce the free phase oil, oil-in water type or water-in oil type emulsified oil, and soluble oil which are the main sources of contaminated groundwater. In this study, treatment of contaminated groundwater was performed using the Fenton oxidation process. The optimum conditions for the removal of THP(Total Petroleum Hydrocarbon) were 3 of pH, 25mM of $H_2O_2$ concentration and 25mM of $Fe^{2+}$ concentration. THP and COD(Chemical Oxygen Demand) concentrations decreased less than 1.5mg/L and 40.0mg/L in 7 minutes using DAF and Fenton oxidation process. However it is necessary to install the settling basin as the sludge concentration increased approximately 5 times.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.96-102
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• 2014

To meet the reinforced discharge standards, effect of coagulant PAC (Poly aluminium chloride, 10.4% as $Al_2O_3$) on phosphorous removal in advanced wastewater treatment process (a modified $A^2$/O). 15 mg/L of PAC determined by jar-test was added to influent of settling basin in a modified $A^2$/O consists of anaerobic, anoxic, and oxic chamber which contains Bio-clod and porous polyurethane media. Performance of PAC was tested by supernatant after settling. The removal efficiencies of BOD, COD, TP (total phosphorus) and SP (soluble phosphorus) on biological process with PAC were 96.1%, 88.8%, 97.0% and 98.6%, compared with those on biological process without PAC were 95.4%, 72.4%, 71.6% and 59.5% respectively. 18.4% of TP and 39.1% of SP removal efficiency was increased, although increase of BOD and COD removal rate was not significant. Only PAC addition to influent of settling basin in $A^2O$ process can help total phosphorus removal to 0.13 mg/L with following discharge standard.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.916-927
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• 2010

In general water treatment process, the disinfection process by chlorine is used to prevent water borne disease and microbial regrowth in water distribution system. Because chlorines were reacted with organic matter, carcinogens such as disinfection by-products (DBPs) were produced in drinking water. Therefore, a suitable injection of chlorine is need to decrease DBPs. Rechlorination in water pipelines or reservoirs are recently increased to secure the residual chlorine in the end of water pipelines. EPANET 2.0 developed by the U.S. Environmental Protection Agency (EPA) is used to compute the optimal chlorine injection in water treatment plant and to predict the dosage of rechlorination into water distribution system. The bulk decay constant ($k_{bulk}$) was drawn by bottle test and the wall decay constant ($k_{wall}$) was derived from using systermatic analysis method for water quality modeling in target region. In order to predict water quality based on hydraulic analysis model, residual chlorine concentration was forecasted in water distribution system. The formation of DBPs such as trihalomethanes (THMs) was verified with chlorine dosage in lab-scale test. The bulk decay constant ($k_{bulk}$) was rapidly decreased with increasing temperature in the early time. In the case of 25 degrees celsius, the bulk decay constant ($k_{bulk}$) decreased over half after 25 hours later. In this study, there were able to calculate about optimal rechlorine dosage and select on profitable sites in the network map.