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박철휘,정태학 ( Chul Hwi Park,Tai Hak Chung ) 한국물환경학회 1996 한국물환경학회지 Vol.12 No.3
Operational characteristics of the UASB Process were studied using a l㎥ pilot plant treating wastewater from a starch manufacturing industry. The reactor was operated with a HRT of 8 hours and the temperature was maintained at 35, 30, 25, and 20℃ for a significant period. COD loading rate varied from 7 to 14㎏/㎥-day as a result of fluctuating influent COD concentration. Both COD removal and the gas production decreased gradually as the temperature decreased. However, reduction of the treatment efficiency at low temperatures was not severe at all. Gas production decreased from 0.256㎥ per ㎏ COD removed to 0.191 as the temperature droped from 35℃ to 20℃. VS reduction efficiency also decreased gradually as the temperature decreased. Although slight increase of the volatile fatty acid was observed at low temperatures, stability of operation based upon pH, alkalinity and volatile fatty acid was maintained at all temperatures. It is believed that stable operation at low temperatures is possible due mainly to accumulation of active sludge granules in the reactor. The sludge granules, 0.7 to 1.2㎜ in size, were mostly composed of rod shaped and filamentous microorganisms with a number of pores.
Media 를 이용한 4Stage BNR 운전특성에 관한 연구
박철휘(Chul Hwi Park),정운택(Woon Taeg Jung) 한국수처리학회 2001 한국수처리학회지 Vol.9 No.1
N/A The objective of this study was to investigate the operating condition and the design parameter for the BNR in STP by 4 stage BNR with media. The effulent of primary settler in STP was fed to the pilot plant. The hydraulic retention time(HRT), temperature, COD/TKN ratio and COD/TP ratio were varied to examine the removal efficiency. In the HRT of 10, 8, 6 and 6hr(winter) at media reactor, the removal efficiencies of BOD, COD, SS, TN and TP were 80∼93.9%, 88∼92.7%, 86.2∼92.4%, 41.8∼62.6%, 43.3∼64.4% respectively, and showed the best efficiency at 6hr because of optimim organic loading rate. The media reactor could obtain a stable effulent quality in range of SNR of 1.5∼2.5㎎TKN/gMLVSS·hr by temperature and SDNR 2.2∼3.2㎎NO₃/gMLVSS·hr by COD/TKN ratio and COD/TP ratio due to the biomass.
박철휘(Chul Hwi Park) 한국수처리학회 1997 한국수처리학회지 Vol.5 No.3
Due to the complexity of the anaerobic digestion process, representing it with a mathematical model is more difficult than any other process. In these days, mathematical models for the kinetic behavior of the microorganisms for the Upflow Anaerobic Sludge Blanket which maintains high concentration of the microorganisms and settling efficiency by forming granular sludges through the self-immobilization of the microorganisms are being developed. In this research, using the experimental results, the simplified kinetic model of the UASB process is described. The UASB reactor can be divided in three compartments : the sludge bed and sludge blanket, both perfectly mixed with respect to the liquid phase, and a plug flow settling region. The mass balance for the concentration of influent and effluent, biomass concentration and gas production rate in two sludge bed and blanket is established. By this simplified model, simulation and verification is studied using the experimental analysis and data from lab scale and pilot plant. It is investigated that the calculated value is almost fitted to the experimental data and coefficient of temperature effect, the ratio of biomass in the sludge bed and blanket and biological kinetic parameters are appropriated.
침지형 분리막을 이용한 하수의 재이용 및 고도처리공정 최적화 연구
박철휘 ( Chul Hwi Park ),윤재곤 ( Jae Gon Yun ),신우균 ( Woo Kyun Shin ) 한국수처리학회 2004 한국수처리학회지 Vol.12 No.2
N/A This study was conducted to examine the sewage reuse system that was consisted of single aerobic MBR in first test run and MLE MBR system, a kind of BNR process, considering membrane fouling and performance in second test run. The HRT of single aerobic MBR was 2hr, and the effluent quality was good enough for reuse water. And then, the MBR process was transformed into MLE MBR process which was operated with HRT of 4hr (anoxic: 2hr, aerobic: 2hr) from 66th day operation. In that process, removal efficiency of BOD_(5), COD_(Cr), SS, T-N were 96.8%, 88.6%, 98.9%, 55% respectively. Although influent average C/N ratio was 1.93 in MLE MBR process operation, nitrification rate, specific nitrification rate, denitrification rate and specific denitrification rate were 83.35%, 0.07gNH₃-N/gMLVSS·day, 56.92% and 0.06gNO₃-N/gMLVSS·day respectively in overall study period. The recovery rate in MBR process was best when the cleaning interval was 10 minutes with washing mode of 30 sec.
치근단 감염 치아의 치근단 수술 후 예후에 관한 후향적 연구
김현민,박철휘,이상칠,김동우,박대송,정진환,이슬기,송민석,Kim, Hyeon-Min,Park, Chul-Hwi,Lee, Sang-Chil,Kim, Dong-Woo,Park, Dae-Song,Jung, Jin-Hwan,Lee, Seul-Ki,Song, Min-Seok 대한악안면성형재건외과학회 2010 Maxillofacial Plastic Reconstructive Surgery Vol.32 No.3
Purpose: The purpose of this retrospective clinical study was to monitor the outcomes of periapical surgery in periapically infected tooth with or without retrograde filling materials (MTA or IRM). Patients and Methods: A total of 85 teeth in 63 patients were included in the study between November 2004 and August 2008. Randomly, MTA or IRM was used as a retrograde filling material or only apical resection without retrograde filling. Teeth with advanced periodontal bone loss or presence of root fracture were excluded from the study. The patients were subjected to a minimum follow-up period of 12 months, with a mean of 17.1 months. Results: Successful healing was observed in 83.3% of the MTA-treated teeth, 80% of the IRM-treated teeth and 75% of the teeth which was not retrograde filling. Doubtful healing was seen 9.3% (MTA), 13.3% (IRM), 12.5% (no retro-filling). The success rate of upper incisors (92%) was higher than lower lincisor and molars (66.7% and 50%, respectively). Conclusion: In this study, periapical surgery including retrograde filling improves the prognosis. And, no statistically significant differences were found between retrograde filling materials (MTA or IRM).
Development and Application of a Landfill Gas Migration Model
박유철,이강근,박철휘,김용우,Park, Yu-Chul,Lee, Kang-Kun,Park, Chul-Hwi,Kim, Yong-Woo The Korean Society of Economic and Environmental G 1996 자원환경지질 Vol.29 No.3
폐기물 매립지 내에셔 가스 흐름을 추정하기 위하여 수치 모델을 개발하였다. 가스 흐름은 밀도에 영향 받는 밀도류이고 매립지 내의 매체는 매우 불균질하므로 단순한 수학적 해법으로 가스 흐름을 추정하기 어렵다. Darcy 방정식과 절량 보존의 법칙을 결합하고 이상 기체 방정식을 도입하여 지배방정식을 만들어지고, 이 지배방정식을 유한요소법으로 풀이하였다. 정류상태 모의의 결과는 AIRFLOW 모델에 의한 모의 결과와 일치한다. 부정류 상태 모의 결과는 질량 보존 평가와 일정 시간 후의 결과를 정류상태의 결과와 비교하여 간접적으로 결과의 신뢰성을 평가하였다. 대우건설에서 1993년에 실시한 난지도 매립지 가스 추출 시험 결과를 모델을 사용하여 분석하였다. 개발된 모델은 1994년 재단법인 한국컴퓨터 프로그램 보호회에 등록되었다. numerical model is developed to estimate gas flow in the landfill site. Darcy's law, the mass conservation law, and the ideal gas state equation are combined to compose the governing equation for the steady-state and transient-state gas flows. The finite element method (FEM) is used as the numerical solution scheme. Two-dimensional radial symmetric triangular ring element is used to discretize the simulation domain. The steady state model developed in this study is compared with AIRFLOW that is a commercial model developed by Hydrologic Inc. Mass balance test is performed on the transient gas flow simulation. The developed model is applied to analyze the gas extraction experiment performed by Daewoo Institute of Construction Technology at the Nanjido landfill in 1993. The developed model was registered at Korea Computer Program Protection Foundation.
미생물 고정화 담체를 이용한 충전율 및 질산화·탈질 속도에 관한 연구
신동철,서정미,박철휘,Shin, Dong-chul,Seo, Jung-mi,Park, Chul-hwi 대한환경공학회 2018 대한환경공학회지 Vol.40 No.2
본 연구는 특정 미생물을 고정화시킨 PVA (Polyvinyl Alcohol) gel을 이용한 질산화 탈질 반응속도를 분석하였다. 질산화용 담체는 질산화 미생물인 Nitrosomonas europaea, Nitrobacter spp.를 혼합 배양하여 고정화시켰으며 탈질용 담체는 탈질 미생물인 Psuedomonas, Bacillus, Paracoccus를 고정화시켰다. 미생물 고정화 담체의 효율을 분석하기 위하여 우선 충전율 결정결과 15% (v/v)이 효과적으로 나타났다. 질산화 반응속도는 $12.53mg\;{NH_4}^+-N/L{\cdot}hr$, 탈질 반응속도는 $20.37mg\;{NO_3}^--N/L{\cdot}hr$로 기존 반응속도(질산화 : $3.93mg\;{NH_4}^+-N/L{\cdot}hr$)보다 빠르게 나타났다. 미생물의 고정화 여부를 확인하기 위하여 미생물 고정화 전 후의 담체를 대상으로 SEM/EDX (Scanning Electron Microscopy/Energy Dispersive X-ray Analyser)를 분석한 결과, C와 N의 성분이 각각 58.5%와 3.85%에서 70.75%와 7.69%로 증가하였다. 결론적으로 미생물 고정화 담체를 적용할 경우 높은 처리효율을 얻을 수 있고 처리시설 규모를 줄일 수 있는 장점을 확인하였다. This study investigated characteristics of nitrification/denitrification rate using PVA (Polyvinyl Alcohol) gel immobilized with specific microorganisms. The media for nitrification and denitrification were producted by immobilizing nitrifying microorganisms (Nitrosomonas europaea and Nitrobacter spp.) and denitrifying microorganisms (Psuedomonas, Bacillus and Paracoccus), respectively. When the media filling rate was the 15% (v/v), the microorganism - immobilized media indicated optimum efficiency. The nitrification rate was $12.53mg\;{NH_4}^+-N/L{\cdot}hr$ and the denitrification rate was $20.37mg\;{NO_3}^--N/L{\cdot}hr$, which was faster than the conventional reaction rate (nitrification: $3.93mg\;{NH_4}^+-N/L{\cdot}hr$). In order to confirm microbial immobilization, SEM/EDX (Scanning Electron Microscopy/Energy Dispersive X-ray Analyser) analysis of media before and after immobilization was conducted. It showed that the contents of C and N increased from 58.5% and 3.85% to 70.75% and 7.69%, respectively. These results suggest that application of microorganism immobilized media improves treatment efficiency and can also reduce the size of the treatment facility.