• International Journal of Naval Architecture and Ocean Engineering
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• 제4권4호
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• pp.403-411
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• 2012

This study presents the nano-sized particle emission characteristics from a small turbocharged common rail diesel engine applicable to prime and auxiliary machines on marine vessels. The experiments were conducted under dynamic engine operating conditions, such as steady-state, cold start, and transient conditions. The particle number and size distributions were analyzed with a high resolution PM analyzer. The diesel oxidation catalyst (DOC) had an insignificant effect on the reduction in particle number, but particle number emissions were drastically reduced by 3 to 4 orders of magnitude downstream of the diesel particulate filter (DPF) at various steady conditions. Under high speed and load conditions, the particle filtering efficiency was decreased by the partial combustion of trapped particles inside the DPF because of the high exhaust temperature caused by the increased particle number concentration. Retarded fuel injection timing and higher EGR rates led to increased particle number emissions. As the temperature inside the DPF increased from $25^{\circ}C$ to $300^{\circ}C$, the peak particle number level was reduced by 70% compared to cold start conditions. High levels of nucleation mode particle generation were found in the deceleration phases during the transient tests.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.412-414
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• 2009

In recent times, starting up polymer electrolyte membrane fuel cells(PEMFC) in sub-zero condition is a great challenge of fuel cell electric vehicle(FCEV). The water produced in a cathode during PEMFCs operate. The water changes into the form of solid/ice in sub-zero temperatures and this makes trouble in PEMFC cells. Voltage of PEMFC drops and cold startup is failed. This paper describes an experimental study on the effect of thermal cycle to degradation of MEA in PEMFC.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.335-340
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• 2000

Most vehicle's exhaust emissions come from the cold transient period of the FTP-75 test. In this study, UEGI technology was developed to help close-coupled catalytic converter (CCC) reach light-off temperature within a few seconds after cold-start. In the UEGI system, unburned exhaust mixture is ignited by four glow plugs installed upstream of the catalyst. Experimental results showed that the temperature of CCC rises faster with the UEGI technology, and the CCC reaches light-off temperature earlier. Under the conditions tested, the light-off time of the baseline case was 62 seconds and that of the UEGI case was 33 seconds.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.33-36
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• 2008

Cell degradation when anode channels are blocked during cold start up was tested and measured. Proton exchange membrane fuel cell (PEMFC) stacks with several configurations of channel blockages were operated and decay in performance was analyzed. When only channels near hydrogen inlet were blocked, performance was rarely changed. In contrast, significant cell reversal occurred and considerable amount of $CO_2$ was produced when all channels near inlet and outlet were blocked. In the case, it was also observed that performance was severely decreased in the area where hydrogen was not supplied sufficiently.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.43-49
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• 2001

In order to satisfy the ULEV emissions regulation, fast light-off of a catalyst is essential for reduction of HC and CO emissions during the cold start. Cranking Exhaust Gas Ignition(CEGI) method developed in this study showed that the catalyst reaches the light-off temperature in a few seconds. The CEGI stops the ignition signal for a few seconds during the cranking period, so the unburned fuel-air mixture bypasses the combustion chamber and flows through the exhaust manifold. When the unburned mixture reaches two glow plugs installed upstream of the catalyst, it burns and releases the thermal energy to heat up the catalyst, In the FTP-75 vehicle tests, the CEGI showed that the exhaust emissions reduced by 47.7% for THC and by 88.6% for CO in the cold-transient phase of the test.

• Journal of Information Processing Systems
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• 제17권2호
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• pp.426-439
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• 2021

To alleviate the cold-start problem and data sparsity in web service recommendation and meet the personalized needs of users, this paper proposes a personalized web service recommendation method based on a hybrid social network and multi-objective immune optimization. The network adds the element of the service provider, which can provide more real information and help alleviate the cold-start problem. Then, according to the proposed service recommendation framework, multi-objective immune optimization is used to fuse multiple attributes and provide personalized web services for users without adjusting any weight coefficients. Experiments were conducted on real data sets, and the results show that the proposed method has high accuracy and a low recall rate, which is helpful to improving personalized recommendation.

• 전기전자학회논문지
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• 제18권1호
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• pp.152-158
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• 2014

본 연구에서는 저온유동성 성능검사 시스템 구현을 통해 디젤 차량용 통합형 연료히터의 성능을 평가한다. 저온 유동성 시험장치에서 $+20{\sim}-30^{\circ}C$ 온도범위에 따라 분리형과 통합형 연료히터 성능을 비교하고, 필터 전후에 따라 유압과 시동시간, 히터의 소모전력을 측정한다. 이때 다양한 종류의 필터면적을 사용함으로써 통합형 연료히터와 분리형을 비교한 결과 시동 시간이 23% 향상되었고, 저온시동성능은 19% 정도 향상된다.

• 한국추진공학회지
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• 제5권2호
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• pp.32-37
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• 2001

본 논문에서는 현재 시판되고 있는 주요 정유회사의 MTBE 가솔린을 이용하여 차량 배출 배기가스를 측정하였다. 배출 가스량은 차량 동력계상에 실제차량을 탑재하여 시험차량의 배기관에서 배출된 배출가스를 포집 하였으며, 우리나라의 공인배출가스 시험방법인 CVS-75 모드를 추적 주행하여 측정 하였다. CVS-75 모드는 cold start cycle, hot stabilized cycle 및 hot start cycle로 구성되며, 본 실험에서 분석한 배출가스는 일산화탄소, 질소산화물 및 탄화수소 등이다. 실험결과 배출 가스의 양에 있어서 근소한 차이만 보이고 있음을 알 수 있었다.

• International Journal of Automotive Technology
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• 제3권1호
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• pp.41-46
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• 2002

Effect of secondary air injection (SAI) on hydrocarbon reduction has been investigated in a single cylinder Sl engine operating at cold-steady/cold-start conditions. The hydrocarbon emission and exhaust gas temperature with and without catalytic converter were compared with continuous and synchronized SAIs, which injected secondary air intermittently into exhaust port. Effects of SAI location, SAI pressure, SAI timing, and location of catalytic converter have been investigated and the results are compared for both SAls with base condition. At cold-steady condition, the rate of HC reduction increased as the location of SAI was closer to the exhaust valve for both synchronized and continuous SAls. The emission of HC decreased with increasing exhaust-A/F when it was rich, and was relatively insensitive when it was lean. The timing of SAI in synchronized SAI had significant effect on HC reduction and exhaust gas temperature and the synchronized SAI was found to be more effective in HC reduction and exhaust gas temperature compared to the continuous SAI . At cold-start condition, when the catalytic converter was located 20 cm downstream from the exhaust port exit, the catalytic converter warm-up period for both SAls decreased by about 50%, and the accumulated hydrocarbon emission during the first 120 s decreased about by 56% and 22% with the synchronized and continuous SAIs, respectively, compared to that of the base condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2910-2915
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• 2008

This paper was investigated the behaviors of the engine and combustion phenomena for various LPG compositions in the semi-return type system, which is not recircurated to LPG tank through furl rail, applied LPi engine during a cold idle condition and including a cold start of the engine. Cyclic HC and NOx emissions were measured at exhaust port to examine their formation mechanical and reduction mechanical with fast response gas analyzers. Various ignition timing is experimented to study the characteristics of combustion phenomena, HC/NOx emissions during fast idle. Also, this study was investigated start delay time, cylinder pressure, HC/NOx emissions, Mass Fraction Burned, starting time to evaluate performance of transient cold startability. Compared to the return type system, the semi-return type system have advantages in point of production cost and equivalent performance of engine starting time and pressure settling time.