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유입흐름 변경 및 전응집 기반 이단응집 제어 적용 MBR을 통한 총인처리 개선 연구
차재환,신경숙,박승국,신정훈,김병군 대한상하수도학회 2017 상하수도학회지 Vol.31 No.1
A membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation was evaluated in terms of phosphorus removal efficiency and cost-savings. The MBR consisted of two identical alternative reaction tanks, followed by aerobic, anoxic and membrane tanks, where the wastewater and the internal return sludge alternatively flowed into each alternative reaction tank at every 2 hours. In the batch-operated alternative reaction tank, the initial concentration of nitrate rapidly decreased from 2.3 to 0.4 mg/L for only 20 minutes after stopping the inflow, followed by substantial release of phosphorus up to 4 mg/L under anaerobic condition. Jar test showed that the minimum alum doses to reduce the initial PO4-P below 0.2 mg/L were 2 and 9 mol-Al/mol-P in the wastewater and the activated sludge from the membrane tank, respectively. It implies that a pre-coagulation in influent is more cost-efficient for phosphorus removal than the coagulation in the bioreactor. On the result of NUR test, there were little difference in terms of denitrification rate and contents of readily biodegradable COD between raw wastewater and pre-coagulated wastewater. When adding alum into the aerobic tank, alum doses above 26 mg/L as Al2O3 caused inhibitory effects on ammonia oxidation. Using the two-stage coagulation control based on pre-coagulation, the P concentration in the MBR effluent was kept below 0.2 mg/L with the alum of 2.7 mg/L as Al2O3, which was much lower than 5.1∼7.4 mg/L as Al2O3 required for typical wastewater treatment plants. During the long-term operation of MBR, there was no change of the TMP increase rate before and after alum addition.
안전한 고객수송서비스를 위한 KTX-II RAMS 적용기준
차재환(Cha Jae-hwan),정인수(Chung In-soo),조광우(Jo Kwang-Woo) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
Currently, it has been a fashion to include RAMS of rolling stock in the order for purchasing the rolling stock. However, it’s only to suggest a qualitative value or an ideal target without giving or demonstrating actual RAMS target, with only demonstrating passive RAMS by the data provided by the manufacturer. In the case of KTX project of 100 cars of KTX-Ⅱ contracted in June 2006, their target has been suggested from the previous RAMS application standard and it aimed to achieve the reliability level of equivalent high speed rolling stock. Afterward, as actual KTX-Ⅱ RAMS Plan and RAMS Demonstration Plan has been prepared and approved, it has been the first problem to secure the reliability and safety in order to introduce the new high speed rolling stock(KTX-Ⅱ) successfully and we actually tried to apply overseas RAMS standard, KTX samples, electric railcar MTRC and rolling stock samples. This Report was dealt world trends of Railway RAMS standard, KTX-II RAMS Specifications, the present condition of KTX-II RAMS performance and development a way of KTX-II RAMS, We hope the “KTX-Ⅱ RAMS Application Standard for Safety of Passenger Transportation Service” is served as an opportunity for the basic research for establishing and demonstrating RAMS target of components or parts composing the rolling stock system.
비전과 초음파 센서를 이용한 임의 환경에서 2족 로봇의 경로계획을 위한 맵 빌딩
차재환(J. W. Cha),김동일(D. I. Kim),기창두(C. D. Kee) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
This paper describes map building for the path planning to avoid obstacles with vision sensor and ultrasonic sensor. We get the 2 dimensional information from the processed images of CCD sensor and 1 dimensional range information from ultrasonic sensor. I proposed a way to generate the map which contains these two kinds of information in the program. And we made the biped robot which have 20 DOF with these sensors and get good experimental result to prove the validity of the proposed method.