• 수산해양기술연구
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• 제49권4호
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• pp.385-394
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• 2013

This study has conducted a comparative analysis on the fishing efficiency of LED fishing lamps by squid jigging vessels, the Yeongrak-ho (16 tons) and Somang-ho (9.77 tons), which operated during September and October 2010 and during October 2011, comparing with MH (Metal Halide) fishing lamp-equipped fishing vessels. This study has also examined vessel's fuel consumption level. The light powers of LED fishing lamps of the Yeongrak-ho and Somang-ho were 25.8kW and 32kW, respectively. Those of the MH fishing vessels, that is, the MH fishing lamp-equipped fishing vessels, were 105kW and 81kW, respectively. The average squid catch in number of an LED vessel, Yeongrak-ho, was 39.2% of the MH fishing lamp-equipped fishing vessels; however, that of the Somang-ho improved to 78.7% of the MH fishing lamp-equipped vessels. Average catch in number by Yeongrak-ho crew was 2.6 times more than catch in number by automatic jigging machines. Average catch in number by MH fishing vessel crew was 1.8 times more than that by automatic jigging machines. An LED vessel, Yeongrak-ho's fishing rate was 17.5%~152.2% of the MH fishing vessels, that is, 61.1% on average, in comparison of combined catch in number per automatic jigging machine and per crewmember. Somang-ho's fishing rate was 6.7%~127.6% of the MH fishing vessels, that is, 73.1% on average. The average fuel consumption level of the Somang-ho, throughout its departure from to arrival at the port, was 475.7l, and that during fishing hours was 109.6l, or 23.0% of the total fuel consumption level. Somang-ho's fuel consumption level per fishing hour was 9.7l on average.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1436-1448
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• 2006

This paper describes the effects of injection rate shaping on the combustion, fuel consumption and emission of $NO_x$ and soot of a medium duty diesel engine. The focus is on the influence of four different injection rate shapes, square type 1, square type 2, boot and ramp, with a variation of maximum injection pressure and start of injection (SOI). The experiments were carried out on a 1 liter single cylinder research diesel engine equipped with an amplifier-piston common rail injection system, allowing the adjustment of the injection pressure during the injection event and thus injection rate as desired. Two strategies to maintain the injected fuel mass constant were followed. One where rate shaping is applied at constant injection duration with different peak injection pressure and one strategy where rate shaping is applied at a constant peak injection pressure, but with variable injection duration. Injection rate shaping was found to have a large effect on the premixed and diffusion combustion, a significant influence on $NO_x$ emissions and depending on the followed strategy, moderate or no influence on soot emission. Only small effects on indicated fuel consumption were found.

• Journal of Astronomy and Space Sciences
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• 제25권4호
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• pp.361-374
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• 2008

Recently, satellite formation flying has been a topic of significant research interest in aerospace society because it provides potential benefits compared to a large spacecraft. Some techniques have been proposed to design optimal formation trajectories minimizing fuel consumption in the process of formation configuration or reconfiguration. In this study, a method is introduced to build fuel-optimal trajectories minimizing a cost function that combines the total fuel consumption of all satellites and assignment of fuel consumption rate for each satellite. This approach is based on collocation and nonlinear programming to solve constraints for collision avoidance and the final configuration. New constraints of nonlinear equality or inequality are derived for final configuration, and nonlinear inequality constraints are established for collision avoidance. The final configuration constraints are that three or more satellites should form a projected circular orbit and make an equilateral polygon in the horizontal plane. Example scenarios, including these constraints and the cost function, are simulated by the method to generate optimal trajectories for the formation configuration and reconfiguration of multiple satellites.

• 한국안전학회지
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• 제8권4호
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• pp.3-15
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• 1993

A multi-cylinder four cycle spark ignition engine equipped with on exhaust gas recirculation(EGR) system to reduce nitric oxide emission and to improve fuel consumption rate has been comprehensively simulated In a computer program including intake and exhaust manifolds. To achieve these goals, this program was tested against experiments performed on a standard production four cylinder four cycle gasoline engine with EGR system. As EGR rate Increased, the maximum temperature of combustion chamber and NO omission concentration decreased under each driving condition. But the emission concentration of CO didn't change much through whole district in spite of the increase of EGR rate. Fuel consumption rate improved under each driving condition according to the increased of EGR rate until 10 percent EGR rate. Therefore the degree of EGR depend not only on the NO emission but also on the economy and the engine performance criteria of the engine.

• 에너지공학
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• 제19권3호
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• pp.171-176
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• 2010

천연가스-수소 혼합가스를 엔진 연료로 사용하는 방법은 배기가스 저감뿐만 아니라 다가올 수소에너지 시대를 대비하여 수소 인프라를 구축하는 데도 의의가 있다. 또한 수소 혼합 천연가스 연료 엔진은 천연가스 엔진 보다 더 높은 열효율 확보할 수 있어 에너지의 효율적 사용에 있어서도 매우 우수한 연료이다. 본 연구에서는 시내버스가 가장 많이 운전되는 조건인 아이들 조건을 대상으로 수소 혼합 천연가스 연료가 연료소모량과 배기가스 저감에 미치는 영향을 파악하였다. 실험 결과 수소 혼합 천연가스 연료는 천연가스에 비해 아이들 조건에서 연료소비율이 20%이상 저감되었으며 유해 배출가스인 THC, NOx를 근원적으로 저감시킴을 확인할 수 있었다.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.22-28
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• 2008

Generally block imbedded type oil pump is adopted to make a small engine. In this paper 1D/3D numerical simulations were conducted to reduce energy consumption of the block imbedded type oil pump. At each stage of engine development we have estimated the oil flow rate and pressure to optimize oil pump sizes by using the 1D system analysis and then accomplished 3D CFD(Computational Fluid Dynamics) simulations to optimize oil pump shapes including inlet/outlet port. As a result, the energy consumption of oil pump has been reduced to nearly 27% and the engine fuel consumption to $1{\sim}1.5%$.

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1035-1040
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• 2011

본 논문에서는 IMO에서 논의 중인 운항선의 에너지효율지표에 대하여 연구를 수행하였다. IMO의 온실가스 저감을 위한 정책방안을 살펴보고 그 중 운항선에 대한 에너지효율지표를 분석하였다. 화물량에 대한 연료소비율 산정방법을 이용하는 에너지효율지표를 실제 운항선에 적용하여 결과를 분석하고 문제점을 제기하였다. 이를 바탕으로 엔진 부하에 대한 연료소비율을 이용하는 개선된 에너지효율지표를 제시하고 운항선에 적용하였다. 결과를 통해 개선된 에너지효율지표가 운항선에 대해 합리적인 이산화탄소 배출률을 정의할 수 있다고 판단하였다.

• 대한기계학회논문집B
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• 제31권5호
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• pp.405-415
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• 2007

The effects of recirculated exhaust gas on exhaust emissions under four kinds of nozzle tip with the different fuel consumption rates are experimentally investigated by using an once-through boiler with a FGR system. The purpose of this study is to develop the FGR control system for reducing $NO_x$ emissions in boilers. Intake and exhaust oxygen concentrations, and equivalence ratio are considered to figure out the effect of FGR rate on exhaust emissions at various fuel consumption rates. It is found that $NO_x$ emissions are markedly decreased, while soot emissions are increased owing to the drop of intake and exhaust oxygen concentrations, and the rise of equivalence ratio as FGR rates are elevated. One can also conclude that the reduction in $NO_x$ emissions is more considerably influenced by the variation of equivalence ratio due to the FGR rate than the fuel consumption rate.

• 한국가스학회지
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• 제13권5호
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• pp.1-6
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• 2009

본 논문에서는 LPG 차량의 연비효과에 미치는 대기온도, 증발기의 가스누출, 엔진오일의 점도, 엔진의 부하조건을 실험적으로 고찰하고자 한다. 연비에 대한 시험결과에 의하면, 엔진의 온도가 상승할수록 연비효과도 함께 점차 높아지고 있다. 대기온도가 $24.2^{\circ}C$일 때의 연비는 $1^{\circ}C$일 때보다 13.6% 정도 높게 나타난 것을 알 수 있다. LP가스 누출이 없는 증발기의 연비는 가스누출이 있는 경우에 비해 5.3%나 좋아지는 것으로 확인되었다. 반면에 엔진오일을 새로 교환한 경우의 연비는 9,500km를 주행한 오일에 비해 1.1% 정도 향상된 것으로 나타났으며, 이것은 대기온도나 증발기의 누설조건에 비해 상대적으로 낮은 영향을 미치는 것으로 관찰되었다. 연비에 더 많은 영향을 미치는 요소는 급제동, 급출발, 급가속과 같은 운전조건으로 판단된다. 연비시험 결과에 의하면, 정상출발은 급출발에 비해 32.3%나 연비가 향상되었고, 급가속은 급출발보다 10.8%나 우수한 연비조건을 보여주고 있다. 또한, 급제동은 급출발보다 18.3%나 우수한 연비상태를 나타내고 있다. 결국 비정상적인 주행조건은 정상적인 운전패턴에 비해 연비가 나쁜 것으로 나타났으므로, 연비를 높이기 위해서는 차량의 주행조건을 정상상태로 유지하는 것이 대단히 중요함을 알 수 있다.

• 한국ITS학회 논문지
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• 제14권1호
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• pp.94-102
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• 2015

고속도로 하이패스 이용률은 59.4%(2013년말 기준)로서 지속적으로 증가하고 있는 추세이다. 본 연구에서는 고속도로 영업소를 이용하는 승용차의 연료소모량을 측정하기 위해서 4개 차종을 대상으로 차대 동력계를 이용한 탄소균형법을 적용하였고, 일반 영업소와 하이패스 영업소의 주행 모드 18개를 설정하여 실험하였다. 그 결과 폐쇄식 구간의 경우 차종에 따라 21.0~56.4ml/veh, 개방식 구간의 경우 10.5~28.1ml/veh의 연료소모 절감효과가 있는 것으로 분석되었다. 또한, 하이패스 이용률에 따른 연간 연료비용 절감효과는 이용률 70%일 경우 282~573억원, 80%일 경우 322~655억원, 90%일 경우 362~737억원, 100%일 경우 403~819억원으로 산정되었다.