• 한국항공우주학회지
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• 제44권7호
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• pp.603-610
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• 2016

본 논문에서는 석탄으로부터 생성된 합성천연가스(SNG)의 다양한 연료 조성에 대한 배기가스 배출 특성 및 희석제에 대한 NOx배출 저감에 대해 기술하였다. 예혼합거리가 짧은 부분 예혼합 가스터빈 연소기에서 SNG 연료조성에서의 수소 비율과 입열량, 당량비를 조절해 가며 연소특성을 관찰하였다. 수소 비율에 따른 NOx 배출지수는 유사하게 나타났고, 화염가시화를 통해 화염의 특성을 파악할 수 있었다. CO 배출의 경우 당량비 1 구간에서 특이점이 나타났으며, 이를 화염의 자발광 이미지와 자발광 강도를 통하여 원인을 파악할 수 있었다. 또한 높은 NOx 배출을 저감하기 위하여 질소($N_2$)와 이산화탄소($CO_2$) 희석제를 사용하여 희석제 공급량에 대한 저감 효과를 파악하였다. 이로부터 희석제의 비열과 열용량이 연소로부터 발생한 연소열을 흡수하여 열화에 의한 NOx 배출을 저감하는 효과를 확인하였다.

• 동력기계공학회지
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• 제9권1호
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• pp.14-22
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• 2005

This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel is injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector is water-cooled by a specially designed coolant passage. Investigated are the engine performance and emission characteristics under the wide range of operating conditions such as 40 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, $150\;to\;180^{\circ}C$ in the inlet-air temperature, and $80^{\circ}$ BTDC to $20^{\circ}$ ATDC in the injection timing. A controlled auto-ignition gasoline engine can be achieved that the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide had been significantly reduced by CAI combustion compared with conventional spark ignition engine.

• 상하수도학회지
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• 제13권2호
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• pp.55-65
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• 1999

AF(anaerobic filter)/BAF(biological aerated filter) system and UASB(upflow anaerobic sludge blanket)/BAF system, of which system effluents were recirculated to the anaerobic reactors in each system, were operated in order to investigate the performance in simultaneous removal of organics and nitrogen in high-strength dairy wastewater. Advanced anaerobic treatment processes of AF and UASB were evaluated on applicability as pre-denitrification reactors, and BAF was also evaluated on the performance in oxidizing the remaining organics and ammonia nitrogen. At system HRTs of 4.0 to 4.5 days and recirculation ratios of one to three, the AF/BAF system could achieve more than 99% of organics removals and 64 to 78% of total nitrogen removals depending upon the recirculation ratio. Although the UASB/BAF system also showed more than 99% of organics removals, total nitrogen removals in the UASB/BAF system were 53 to 66% which are lower than those in the AF/BAF system at the corresponding recirculation ratios. Optimum recirculation ratios considering simultaneous removal of organics and nitrogen and cost-effectiveness, were in the range of two to three. The upflow AF packed with crossflow module media, as a primary treatment of the anaerobic reactor/BAF system, showed better performances in denitrification, SS removals, and gas production than the UASB. Higher loading rate of suspended solids from the UASB increased the backwashing times in the following BAF. Especially, at a recirculation ratio of three in the UASB/BAF system, the increase in head loss due to clogging in the BAF caused frequent backwashing, at least once d day. The BAF showed the high nitrification efficiency of average 99.2% and organics removals more than 90% at organics loading rate less than $1.4KgCOD/m^3/d$ and $COD/NH_3-N$ ratio less than 6.4. It was proved that the simplified anaerobic reactor/BAF system could maximize the organics removal and achieve high nitrogen removal efficiencies through recirculation of system effluents to the anaerobic reactor. The AF/BAF system can, especially, be a cost effective and competitive alternative for the simultaneous removal of organics ana nitrogen from wastewaters.

• 상하수도학회지
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• 제11권4호
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• pp.63-70
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• 1997

The objectives of this study were to find out the optimum treatment conditions for removing nitrogen in a synthetic wastewater by using microorganisms immobilized with PVA-Freezing method. The samples used as influents to the laboratory scale treatment units were a synthetic wastewater. The experiments in this study were mainly directed to collect the data of nitrogen and organic matter removal efficiencies for the different hydraulic and internal recycle rates conditions, temperature and influent C/N ratios. The removal efficiencies of nitrogen and organic matters were investigated for the operating conditions of HRT 2~12hours, internal recycle rates 50~400%, temperatures $15{\sim}30^{\circ}C$ and C/N ratios 2.5~7.5. The adequate internal recycle rate for removing T-N and $BOD_5$ in the synthetic wastewater was found to be about 300% at the temperature of $30^{\circ}C$ when the ratio of carbon contents to the nitrogen (C/N) in the influent was around 5.5. Under these conditions, the final effluent concentrations of T-N and $BOD_5$ were 8.7 and 8.4 mg/l, respectively.

• 생태와환경
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• 제51권1호
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• pp.96-104
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• 2018

안정동위원소비는 전 세계적으로 수생태 환경 연구에서 매우 활발하게 적용되고 있는 분야로써, 국내에서도 2000년대 이후 담수 및 연안 생태계의 먹이망 구조 연구 등 다양한 연구에서 활용되고 있다. 최근에는 기존의 총 조직내의 안정동위원소 분석기법의 한계점을 인지하고 보완하기 위한 방안으로 아미노산의 질소 안정동위원소 분석 기법이 개발되었으며, 이를 활용한 다양한 연구 사례들이 보고됨에 따라 수생태 연구의 활용범위가 급격히 확대되고 있다. 아미노산의 질소 안정동위원소 분석기법의 기술적인 접근성의 한계에 의해 현재까지 국내에서 수생태계 연구를 위해 아미노산의 질소 안정동위원소비를 활용한 연구는 제한적인 실정이지만, 국내 다양한 하천 및 호수 그리고 연안의 환경 변화 특성을 고려할 때, 향후 수생태 환경연구에 있어 그 유용성과 활용 가치가 대단히 높을 것으로 전망된다.

• 한국미생물·생명공학회지
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• 제18권1호
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• pp.66-70
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• 1990

부피질호르몬의 제조의 중요한 전구체인 11alpha-hydroxyprogesterone을 Rhizopus nigricans를 이용하여 고농도의 progesterone으로부터 고수율로 생산하기 위한 연구를 수행하였다. 생물전환수율을 최대로 하는 배지조성은 포도당과 casamino acid의 비율이 2:1인 것으로 관찰되었다. Progesterone은 Tween 80 용액에 분산시켜서 종균배양 후 12 시간 정도 지나서 첨가하였을 때 전환수율이 높았다. Progesterone의 농도가 증가함에 따라 생산성이 증가하였고 Progesterone이 20g/$\ell$일 경우 전환수율은 약 70정도 였다.

• 동력기계공학회지
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• 제10권1호
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• pp.19-24
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• 2006

This work treats a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel was injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector was water-cooled by a specially designed coolant passage. The engine performance and emission characteristics were investigated under the wide range of operating conditions such as 40 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, 150 to $180^{\circ}C$ in the inlet-air temperature, and $60^{\circ}$ BTDC in the injection timing. The ultra lean-burn with self-ignition of gasoline fuel by heating inlet air was achieved in a controlled auto-ignition gasoline engine. It could be also achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide significantly reduced by CAI combustion compared with conventional spark ignition engines.

• 한국버섯학회지
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• 제18권2호
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• pp.135-140
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• 2020

산느타리 배지재료별 적정 혼합비율을 구명하기 위하여 1 kg 봉지재배를 통해 배지의 화학성과 2주기까지의 버섯 수량간 관계를 분석한 결과, 1주기 버섯 수확량은 총 질소량과 상관을 보였는데, 총 질소량 1.1% 부근에서 최대의 수량을 보였고 그보다 질소량이 적거나 많은 경우 수량이 적어지는 경향을 보였다. 또한 2주기 버섯 수확량은 총질소, 총탄소, C/N율 등 여러 가지 화학성과 높은 상관을 보였는데, 질소함량 1% 이상의 구간에서 질소함량이 높을수록, 탄소함량 13% 이상의 구간에서 탄소함량이 높을수록 수량이 증가되는 양상을 보였다. 따라서 산느타리 재배시 혼합배지의 질소함량이 1.1% 정도인 경우 1주기 버섯수량이 가장 높았고, 2주기 수량은 질소와 탄소의 함량이 높은 배지에서 높은 경향을 보였다. 다만, 면실피가 다량 첨가된 배지에서 대두박과 케이폭박이 합계 20% 첨가되면 버섯 발생에 문제가 생길 수 있으므로 주의해야 할 것이다.

• 한국산업보건학회지
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• 제25권3호
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• pp.392-404
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• 2015

Objectives: This study measured and analyzed the concentrations of crystalline silica, elemental carbon and the contribution ratio of pollutants which influence environmental and respiratory disease around the Ansim Briquette Fuel Complex in Daegu, Korea. Methods: We analyzed the crystalline silica and elemental carbon in the air according to FTIR(Fourier Transform Infrared Spectroscopy) and NIOSH(National Institute of Occupation Safety and Health) method 5040, respectively. In addition, lead stable isotopes, and carbon and nitrogen stable isotopes were analyzed using MC-ICP/MS(Multi Collector-Inductively Coupled Plasma/Mass Spectrometer), and IRMS(Isotope Ratio Mass Spectrometer), respectively. Results: The concentration of crystalline silica in the direct exposure area around the Ansim Briquette Fuel Complex was found to be $0.0014{\pm}0.0005mg/Sm^3$, but not to exceed the exposure standards of the ACGIH(American Conference of Governmental Industrial Hygienists). In the case of the autumn, the direct exposure area was found to show a level 2.5 times higher than the reference area, and on the whole, the direct exposure area was found to have a level 1.4 times higher than the reference area. The concentration of elemental carbon in the direct exposure area and in the reference area were found to be $0.0014{\pm}0.0006mg/Sm^3$, and $0.0006{\pm}0.0003mg/Sm^3$, respectively. This study confirmed the contribution ratio of coal raw materials to residentially deposited dusts in the area within 500 meters from the Ansim Briquette Fuel Complex and the surrounding area with a stable isotope ratio of 24.0%(0.7-62.7%) on average in the case of carbon and nitrogen, and 33.9%(26.6-54.1%) on average in the case of lead stable isotopes. Conclusions: This study was able to confirm correlations with coal raw materials used by the Ansim Briquette Fuel Complex and the surrounding area. The concentration of some pollutants, crystalline silica, and elemental carbon emitted to the direct-influence area around the Ansim Briquette Fuel Complex were relatively higher than in the reference area. Therefore, we need to impose continuous and substantive reduction countermeasures in the future to prevent particulate matter and coal raw materials in the study area. It is time for the local government and authorities to prepare active administrative methods such as the relocation of Ansim Briquette Fuel Complex.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.414-417
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• 2000

기존의 BACC process의 가장 큰 단점은 탈질이 잘 이루어지지 않는다는 점인데 이것을 보완한 modified BACC process의 경우 실제오수를 사용하여 외부 반송비 따른 질소 및 인의 제거율을 살펴보면 외부 반송비가 200%일 때 $CODC_{Cr}$의 제거율은 평균 $96.3{\sim}95.7%$ 기존의 BACC process와 비슷하나 T-N 제거율은 $88.3{\sim}95.7%$로 월등히 우수한 결과를 보여주고 있다. 충진율 실험에서는 Table 2에서 보는 바와 같이 큰 차이는 없었다.