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악취센서를 이용한 실시간 악취 모니터링 장치의 축산농가 현장 적용 평가
오민환,이은영 한국냄새환경학회 2018 실내환경 및 냄새 학회지 Vol.17 No.3
In this study, the odor generated in a livestock farm with 500 heads of finisher breed in 661 m² was monitored during 6 months using a gas sensor, a wired / wireless communication system and database server. Odor unit, ammonia, hydrogen sulfide, and total volatile organic compounds (TVOC) were monitored using the gas sensor. To show the tendency of odorous substances generation, the odor concentration was shown in the graph on a monthly and daily basis. Among the analysis items, the maximum generation of odor was found to be closely related to the generation of hydrogen sulfide. Through observing the daily and monthly trends of odor substances, it was found that each substance was a useful indicator for monitoring odor, because ammonia, hydrogen sulfide, odor and TVOC were increased and decreased in a similar pattern. The odors were highest in the hours of the early morning (00:00-05:00), the evening (18:00-23:00), and the morning (06:00-11:00) in a day. After the use of the microbial agent was discontinued in autumn (October), anaerobic digestion of the manure in a pit proceeded and the amount of hydrogen sulfide increased. Therefore, despite a slight decrease in ammonia production, the odor unit level did not decrease after October but rather was somewhat increased. In the future, the use of the odor monitoring system is expected to improve the efficiency of odor sources management.
돈분뇨와 음폐수를 이용한 혐기성 소화조 운영의 공정별 악취배출 특성평가
오민환,심준규,허혜원,윤태한,이은영 한국냄새환경학회 2014 실내환경 및 냄새 학회지 Vol.13 No.3
This study was performed to measure the concentration of odorous compounds and dilution ratio values at eachpart of the anaerobic digester process with composting facilities using swine manure and food waste. Complexodors, ammonia, volatile fatty acids and sulfur compounds were measured at each part of the process. Complexodors measured during swine manure storage, food waste storage and in the digested liquid tank, were 35,312Odor Unit(OU), 39,086 OU and 17,733 OU, respectively. The odor contribution index was calculated by theconcentration of odorous compounds during each process divided by the threshold limit. As a result, the majorodorous compound that appeared during swine manure storage, food waste storage and in the digested liquid tankwas hydrogen sulfide. On the other hand, the major odorous compound in the other processes was ammonia. Theoverall average concentrations of ammonia were highest in the digested liquid tank(337 ppm) and the separatedliquid tank(131 ppm). Wastewater treatment process(10.9 ppm) and deodorization process(11.6 ppm) revealed thelowest concentration of ammonia. The overall average concentration of total volatile fatty acids(TVFAs) was102.8 ppb during food waste storage and among the TVFAs, the main element was propionic acid(66.1 ppb). Sulfurcompounds were only detected during swine manure storage, food waste storage and in the digested liquid tank. The dominant sulfur compound was hydrogen sulfide during swine manure storage(96.3 ppm) and methylmercaptan during food waste storage(17.7 ppm) and dimethyl sulfide during food waste storage(34.5 ppm).
착륙 안정성을 고려한 달착륙선 충격흡수 시스템의 순차적 근사 최적설계
오민환,양순신,조진연,임재혁,황도순 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11
본 연구에서는 착륙 안정성을 고려한 2단으로 구성된 달착륙선 충격 흡수 장치에 대한 최적화를 수행하였다. 충격 흡수 장치의 복잡한 충격거동을 모사하기 위해 1차원 구성방정식 모델을 제안하였으며, 이와 함께 상용해석 소프트웨어인 ABAQUS를 활용하여 최적화를 위한 2차 다항회귀 메타모델을 구성하였다. 구성된 메타모델을 순차적 근사 최적설계 기법에 적용하여 3차원 달착륙선 모델의 2단 충격 흡수 장치의 최적화를 수행하였으며, 이를 통해 허니컴 구조를 이용한 충격 흡수 장치의 셀크기와 포일 두께 및 하니콤 구조의 면적을 변화시킴에 따라 달착륙선의 월면 착륙 시 충격하중을 크게 저감시킬 수 있음을 확인하였다. In this work, optimization of two-stage shock absorption system for lunar lander considering tip-over has been carried out. Because of complexity of impact phenomena of shock absorption system, a 1-D constitutive model is proposed to describe the behavior of shock absorption system. Quadratic polynomial regression meta-model is constructed by using a commercial software ABAQUS with the proposed 1-D constitutive model, and sequential approximate optimization of two-stage shock absorption system for 3-D lunar lander model has been carried out along with the constructed meta-model. Through the optimization, it is verified that landing impact force on lunar lander can be considerably reduced by changing the cell size, foil thickness and area of honeycomb structure in two-stage shock absorption system.