• International Journal of Safety
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• 제4권2호
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• pp.30-35
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• 2005

In case of tunnel fire, one of the most effective facilities to save lives is the smoke control system. In this study, two different smoke extraction schemes of transversely ventilated tunnel were compared. One is the smoke extraction using the fixed exhaust ports on the false ceiling to achieve the uniform and distributed smoke extraction (uniform exhaust). The other is that using the remote controlled smoke extraction where only vents close to the fire is opened whereas the others are closed to enhance the limitation of the smoke spread (localized exhaust). A number of numerical simulations were performed to find out the optimal smoke extraction rate at each smoke extraction scheme to allow the tunnel users to escape to the safe area without endangering their lives by smoke.

• 한국기계가공학회지
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• 제16권3호
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• pp.76-81
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• 2017

In this research, to cope with the exhaust being reviewed to establish legal regulations for domestic small vessels, a basic experiment on an exhaust emissions post-treatment system was conducted to construct the design data required for securing a localized technology. The data was secured based on the arithmetic mean calculated through setting the engine load to 25%, 50%, and 75% and conducting five. A 2800-cc turbo charger diesel-type engine was used in the experiment, and an engine dynamometer was used in the conducted tests. As a result, NOx was reduced by approximately 20% and PM was reduced by approximately 97%. Although the results indicated no significant changes to CO in test mode-1, it was greatly reduced as it transitioned into the next phase.

• 한국표면공학회지
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• 제42권2호
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• pp.79-85
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• 2009

We aimed to develop a Fe-($16{\sim}19$)Cr-($0.1{\sim}0.6$)Ti-($0.1{\sim}0.6$)Nb stainless steel for automotive exhaust parts with high corrosion resistance. The alloys with high Cr content showed high resistance to general corrosion and also localized corrosion. The increase of Ti and Nb contents resulted in a linear increase in the general corrosion resistance, while the pitting potential was improved by addition of these elements up to about 0.4 wt.%. The low-carbon Fe-17Cr-0.4Ti-0.4Nb alloy annealed at $850^{\circ}C$ and air-cooled was considered to be the optimum alloy for our purpose with the critical anodic current density of $247{\mu}A/cm^2$ in 0.05 M $H_2SO_4$ solution and the pitting potential of 310 mVSCE in 0.2 M NaCl solution.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.77-88
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• 1997

The heat rejection to coolant is a dominant factor for building vehicle cooling system such as radiator and cooling fan. Since the vehicle cooling system also has effects on fuel consumption and noise, the study of heat rejection to coolant has been emphasized. However, the study on heat rejection to coolant has been mainly focused on the field that related to the characteristics of combustion and localized heat loss. It is no much of use in design for the entire cooling system because it is focused on such a specific point. In this work, the heat rejection rate to coolant for four different engines are obtained to derive a simple heat transfer empirical formula that can be applied to the engine cooling system design, and it is compared with the other studies. Also, to observe effects of engine operation factors and heat transfer factors on coolant, we measured the metal temperature and the heat rejection rate. The heat rejection to coolant does not depend significantly upon the coolant flowrate, but mainly upon the amount of air fuel mixture and the air fuel ratio as long as the composition of coolant does not change. The reduction of heat rejection to coolant did not effectively improve the fuel consumption, but was mostly converted to raise the exhaust gas temperature and the oil temperature.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.474-481
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• 2018

친환경자동차의 보급 확대를 위한 정책수립과 기술개발이 지속적으로 이루어지고 있는 실정이나 아직까지도 내연기관이 차지하는 비중은 약 95% 차지하고 있다. 화석연료를 기반으로 하는 내연기관의 엄격한 배기가스규제를 충족시키기 위해 자동차와 선박용 후처리장치의 비중이 점차로 증가하고 있다. 디젤엔진은 이산화탄소 배출량이 적고 강력한 파워와 연료의 경제성을 가지고 있으며, 상용차뿐만 아니라 승용차에서도 시장의 수요가 증가하고 있다. 디젤 연료 특성으로 인하여 질소산화물은 국부적인 고온연소 영역에서 생성되며, 입자상물질은 확산연소 영역에서 생성된다. 희박한 LNT(질소산화물 흡장촉매)와 urea-SCR(선택적인촉매환원장치)는 디젤엔진에서 질소산화물을 저감시키기 위한 후처리장치로 개발되어져왔다. 이 연구는 가혹해지고 있는 배기가스 규제 대응을 위해 선택적인촉매환원장치의 촉매에 포함됨 조촉매의 영향을 파악하는 것이다. 망간-선택적인촉매환원장치의 질소산화물 저감 성능이 가장 우수하였으며, 망간 이온과 Zeolyst의 Al과의 이온교환이 잘 되었고, 활성화 에너지가 낮아 반응 속도가 빨라짐에 따라 질소산화물 저감 성능이 향상되었다. 7Cu-15Ba/78Zeolyst SCR 촉매의 질소산화물 저감 성능은 200도에서 32%, 500도에서 30%를 나타내며 가장 높은 성능을 나타내었고, 조촉매로 첨가된 산화바륨의 질소산화물의 흡장 물질이 Cu-SCR 촉매에 잘 분산되어 있고 Cu-SCR 촉매의 환원 반응과 더불어 산화바륨의 추가적인 질소산화물 저감 성능이 영향을 끼쳤기 때문이다. 7Cu-15Ba/Zeolyst SCR 촉매는 3종 촉매 중 열적 열화에서 내구성이 강하였다. 열적 열화에 따른 동종 성분 산화구리가 이동하여 응집되는데, 산화바륨이 주촉매 산화구리 입자의 응집을 감소시켰기 때문이다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.102-108
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• 2009

Fossil power plants firing lower grade coals or equipped with modified system for NOx controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases' $O_2$, NOx and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective back-pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess $O_2$ and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing NOx emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.

• 한국태양에너지학회 논문집
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• 제29권5호
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• pp.45-52
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• 2009

Fossil power plants firing lower grade coals or equipped with modified system for $NO_x$ controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases' $O_2,\;NO_x$ and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective rear pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess $O_2$ and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing $NO_x$ emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.112-118
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• 2018

화석연료를 기반으로 하는 내연기관의 엄격한 배기가스규제를 충족시키기 위해 자동차와 선박용 후처리장치의 비중이 점차로 증가하고 있다. 디젤엔진은 $CO_2$ 배출량이 적고 강력한 파워와 연료의 경제성을 가지고 있으며, 상용차뿐만 아니라 승용차에서도 시장의 수요가 증가하고 있다. 디젤 연료 특성으로 인하여 질소산화물은 국부적인 고온연소 영역에서 생성되며, 입자상물질은 확산연소 영역에서 생성이 된다. LNT와 urea-SCR 촉매는 디젤엔진에서 NOx를 저감시키기 위한 후처리장치로 개발되어져왔다. 이 연구는 가혹해지고 있는 배기가스 규제 대응을 위해 소형과 중 대형 디젤기관에 많이 사용되고 있는 Cu SCR 촉매의 NOx 저감 성능 향상을 목적으로 한다. $5Cu-2ZrO_2$/Zeolyst(Si/Al=13.7)SCR 촉매는 $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) 촉매에 비해 촉매온도 $300^{\circ}C$ 이상에서 약 5-50% 수준으로 de-NOx 성능이 높았다. Zeolite는 zeolyst에 비해 금속의 분산도가 낮고 평균 입경이 커짐에 따라 촉매의 반응속도가 저하되었다. 10wt% Cu가 담지된 $10Cu-2ZrO_2$/88Zeolyst 촉매는 $200^{\circ}C$에서 40%, $350^{\circ}C$에서 약 65%로 NOx 정화성능이 가장 높았고, Cu의 이온이 제올라이트의 결정화합물인 Al과의 이온교환율이 증가함에 따라 다른 촉매에 비해 20-40% de-NOx 성능이 향상되었다.