• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.4
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• pp.320-328
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• 1994

In 1980 s to 1990 s the marine propulsion diesel engines have been developed into lower speed and longer stroke for the enegy saving (small S.F.O.C). As these new trends the conventional mechanical-hydraulic governors were not adapted to the new requirements and the digital governors have been adopted in the marine use. The digital governors usually use the control algorithms such as the PID control, optimal control, adaptive control and etc. While the engine has delay time and parameter variations these control algorithms have difficulty in considering the stability and the robustness for the model uncertainty. In this study, the $H_{\infty}$ controller design method are applied in order to design the feedback controller K(s) to the speed control of the low speed marine diesel engine, and the two-degree-of-freedom control system is constituted with $H_{\infty}$controller. By comparison of responses of the two-degree-of-freedom control system under the delay time and parameter variations is confirmed.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.4
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• pp.387-392
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• 1998

Recently, among after-treatment devices which have high possibility of utility, diesel oxidation catalyst (DOC) is concerned over the world. DOC oxidizes pollutants by means of activate-reaction during by -passing in the catalyst, in doing so, conversion efficiency of PM, CO and HC is high, and this device does not have an effect on engine performance because back pressure is not nearly increased. But, as a small amount of sulfur content in fuel is oxidized, it makes sulfate, which is absorbed on the surface of catalyst. So, in this study, the experiment is carried out by means of using ordinary fuel (0.1wt%) and low sulfur fuel (0.05wt%) with DOC, and the emission gas of diesel engine is measured.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.106-114
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• 1996

Extensive experiments were conducted to investigate the emission of DI diesel engine by using DMC(dimethyl carbonate) as an oxygenated fuel additives. The results indicate that smoke reduces almost linearly with fuel oxygen contents. Reductions of HC and CO were attained noticeably, while a small increase in NOx was encountered concurrently. The effective reduction in smoke with DMC was maintained with the presence of CO2, which suggested a low NOx and smoke operation could be obtained in combination of using oxygenated fuel and EGR. Further experiment was conducted a thermal cracking set-up for mechanism studies.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.346-351
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• 2011

Medium and high speed marine diesel engines with reduction gear have been widely used as prime mover in small car ferries and fishing vessels. The elastic coupling should be installed and complemented the propulsion shafting system to isolate the vibratory torque between engine and reduction gear. In this paper, the dynamic characteristics of elastic coupling with rubber type circular segments is confirmed by theoretical analysis using the FEM and the hydraulic excitation test at shop. Further adaptation was investigated with the torsional vibration test at diesel engine factory shop.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.2
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• pp.88-97
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• 1984

The combustion process and the performance of a diesel engine are considerably affected by the characteristics of fuel spray. It is known that the spray of swirl nozzle for diesel engine injector of small orifice ratio becomes soft spray that has no core, therefore its penetration, one of the characteristics of spray becomes werse inspite of its good dispersion. In this paper, the spray characteristics of variously designed swirl nozzle for diesel injector were investigated by the photographic method. The nozzles, used in this experiment, vary in the diameter of swirl chambers and orifice ratio. From the results of the study, the sprays of this type nozzle of optimum swirl chamber and orifice ratio show that penetration decreased slightly but dispersion and spray volume increased remarcably, compared with unswirled single hole nozzle of the same size. It was suggested as a reason for the results, that the spray of this type swirl nozzle is similar to hard spray, therefore the core of the spray sustains good penetration considerably.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.63-70
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• 1993

In 1980's to 1990's the marine propulsion diesel engines have been developed into lower speed and longer stroke for the energy saving(small S.F.O.C.). As these new trends the convetional mechnical-hydraulic governors were not adapted to the new requirements and the digital governors have been adopted in the marine use. The digital governors usually use the control algorithms such as the PID control, optimal control, adaptive control and etc. While the engine has delay time and parameter variations these control algorithms have difficulty in considering the stability and the robustness for the model uncertainty. In this study, the $H_{\infty}$ controller design method are applied to the speed control of the low speed marine diesel engine. By comparison the $H_{\infty}$ control results with the PID control results, the validity of the $H_{\infty}$ controller under the delay time and parameter variations is confirmed.

• Journal of ILASS-Korea
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• v.22 no.4
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• pp.197-202
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• 2017

The objective of this study is to investigate the effects of low-temperature combustion (LTC) on the correlations of combustion characteristics and reduction of exhaust emissions in a small DI diesel engine with biodiesel fuel. In order to analyze the combustion, exhaust emission characteristics and distribution of nano size particles for biodiesel were investigated. In addition, to evaluate the effect of LTC on the combustion and emission characteristics, 30 and 50% of cooled-EGR rates were investigated. From these results, it revealed that the influence of LTC on the combustion characteristics showed that the ignition delay significantly increased and reduces peak heat release rate of premixed combustion by lowering reaction rate. With 50% EGR and advanced injection timing, soot and $NO_x$ emissions were simultaneously reduced.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.1
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• pp.35-43
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• 2008

Technical trends of propulsion system for small aircraft are investigated. Currently, most small aircraft are equipped with piston engine, turboprop and turbofan engines, and the technology development is going continuously. For piston engines, new diesel engines are arising besides gasoline engine. The diesel engines use relatively low-cost and easy to get fuel(Jet A), so the demand for small aircraft is getting increased, and new engines with high reliability and efficiency are being developed. For gas turbine engines, application of small turbofan is getting increased for newly arising VLJ market and the engine demand will be rapidly increased in the future. On the other hand, some electric propulsions without fossil fuels are being developed without high cost of fuel and environmental effects. In the future, propulsion system for small aircraft will be developed having enhancement of performance and efficiency with higher reliability and safety.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.07a
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• pp.41-46
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• 2000

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.9-18
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• 1995

The substitution of conventional fuel oil by alternative fuels is of immense interest due to liquid oil shortage and requirements of emission control standard. Among the alternative fuels, natural gas may be the most rational fuel, because of its widespread resource and clean est burning. Meanwhile, engine simulation is of great importance in engine development. Hence a zero-dimensional combustion model was developed for dual-fuel system. Natural gas was injected directly into the cylinder and small amount of distillate was used to provide the ignition kernel for natural gas burning. The intake air and exhaust gas flow was modeled by filling and emptying method. Although the single zone approach has an inherent limitation, the model showed promise as a predictive tool for engine performance. Its simulation was also made to see how the engine performance was influenced by the fuel injection timings and amount of each fuel.