• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.96-103
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• 2007

A program for LAE (liquid Apogee Engine) firing strategy calculation was developed. This program can be used as the first stage of transfer orbit analysis, which process receives input parameters as like initial orbit elements, ground TT&C stations positions, satellite performances and makes firing user-selectable strategies. The developed program is dedicated to GEO satellites which using LAE generally and it can calculate six back-up strategies and deals situation its maximum firing number is six. The MS-EXCEL software was used for the input and output process. And the numerical calculation part was embodied with MATLAB functions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.397-407
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• 2017

In this study, a SCR system is employed to selectively reduce $NO_X$, which is a major cause of environmental pollution and issues in diesel engines. In particular, this paper focuses on the combination of feedforward injection strategies, depending on the NO/$NO_X$ ratio, and feedback injection control, using $NH_3$ coverage ratio, based on a SCR model. A 2.2 L passenger diesel engine, which is equipped with a diesel oxidation catalyst (DOC) and a diesel particle filter (DPF), was used in the experiments. The developed control algorithm is implemented on a real-time computer with injection control algorithm. By analyzing the $NO_X$ emission measurement, the performance of the proposed injection control algorithm is verified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.692-698
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• 2020

This paper examines the effects of a multi-stage pilot split injection strategy on combustion and exhaust emission factors in a single-cylinder diesel engine. One analysis noted that in the single-injection condition, the maximum in-cylinder pressure and rate of heat release were highest. The pilot injection quantity was evenly divided, showing a tendency to decrease as the number of injections increased. In another injection condition, when the multi-stage pilot split injection strategy was applied, IMEP, engine torque, and combustion increased. The COV_IMEP was greatest with the lowest combustion efficiency. The combustion ability was poor. In a single injection condition, the O₂ concentration in the exhaust gas was the lowest and the CO₂ was the highest. When the multi-stage split injection strategy was applied, the low temperature combustion process proceeded, and the oxidation rate of CO₂ decreased while the emission level increased. In a single injection condition in which a locally rich mixture was formed, the HC emission level showed the highest results. A 55.6% reduction of NOx emission occurred under a three-stage pilot injection condition while conducting a multi-stage pilot split injection strategy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.33-39
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• 2019

The improvement of emissions, fuel economy, and combustion noise is a primary target in the development of heavy-duty diesel engines. Multiple injection has been introduced as one of the most promising strategies for this goal. In this research, various multiple injection methods were applied to achieve the optimal strategy in terms of emissions, fuel economy, and combustion noise. In the case of one pilot injection, the smoke emission deteriorated, while the NOx emission was reduced. In the case of 2 pilot injections, the NOx and smoke emissions were reduced by 73% and 84%, respectively. In this case, the combustion noise was analyzed with the maximum pressure-rise rate, and the fuel economy was evaluated with the help of the indicated specific fuel consumption. A 15%:15% 2-pilot injection strategy accomplished improvements of 32.9% for NOx, 60.4% for smoke, 1.95% for fuel consumption, and 19.4% for combustion noise compared to the case of single injection. Based on the data, an optimal injection strategy will be developed for a greater operating range in future work.

• Bulletin of the Korean Space Science Society
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• 2006.10a
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• pp.152-152
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• 2006

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.96-107
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• 2014

Korea Aerospace Research Institute has a plan to launch experimental lunar orbiter in 2017, and lunar orbiter and lander in 2020. In the mission planning phase, LOI(Lunar Orbit Insertion) maneuver strategy should be designed using finite burn model because on-board propulsion system of lunar orbiter in finite burn type. LOI maneuver plan and amount of required ${\Delta}V$ using finite burn model depend on the spacecraft attitude at burn, a type of propellant, thrust level and burn timing. This paper describes the LOI maneuver of lunar orbiter of foreign space agency and then comes up with the LOI maneuver plan of Korean lunar orbiter. Adequate thrust level and burn duration of Korean lunar orbiter also present by performing simulation.

• Product Safety
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• s.51
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• pp.16-18
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• 1996

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.99-105
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• 2011

This paper described the effect of the multiple injections on the emission characteristics and combustion stability in a common rail diesel engine. In order to investigate the influence of multiple injections in a passenger car diesel engine, the injection strategy was varied with pilot injection, post injection and one main injection at various conditions. Based on the experimental results, the combustion and emissions characteristics were analyzed for the various injection strategies such as main, pilot-main, double-pilot-main, double- pilot-main-post injection strategy. It is revealed that the $NO_X$, HC and CO emissions are reduced by double pilot and post injection at medium load, however, soot emission is increased. Also, in the case of multiple injection, the combustion pressure is increased smoothly near the TDC and the coefficient of variation and fuel consumptions are decreased.

• Journal of ILASS-Korea
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• v.23 no.1
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• pp.36-41
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• 2018

Fuel wall film effects power output and cycle deviation by changing the amount of fuel flowing into cylinder in PFI gasoline engines. Reduction of wall film can reduce fuel consumption and improve combustion stability. In this research, the effects of injection strategies including injection pressure and dual injection system is investigated for reducing wall film formation. The CONVERGE software is used for numerical analysis tool and O'Rourke film splash model was used for wall film prediction model. Compared with the reference case wall film decreased with increase of injection pressures, and the film formation reduced when the dual injection system was used.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.335-342
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• 2012

Nowadays, automobile manufacturers are focusing on the reduction of exhaust-gas emissions because of the harmful effects on humans and the environment, such as global warming by greenhouse gases. Gasoline direct injection (GDI) combustion is a promising technology that can improve fuel economy significantly compared to conventional port fuel injection (PFI) gasoline engines. In the present study, ultra-lean combustion with an excess air ratio of over 2.0 is realized with a spray-guided-type GDI combustion system, so that the fuel consumption is improved by about 13%. The level of exhaust-gas emissions and the operation performance with the multiple injection strategy and exhaust-gas recirculation (EGR) are examined in comparison with the emission regulations and from the point of view of commercialization.