• Journal of Korea Foundry Society
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• v.25 no.4
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• pp.145-150
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• 2005

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.2
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• pp.126-131
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• 2007

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.127-138
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• 1998

• Polymer Science and Technology
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• v.7 no.2
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• pp.201-209
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• 1996

• Tribology and Lubricants
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• v.26 no.5
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• pp.291-296
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• 2010

The purpose of this paper is to study the fuel economy improvement experimentally when the viscosity of engine oil is lowered. The emissions are measured for CVS-75 mode with SAE viscosity grades. The test results indicate that a close correlation has been found between the engine oil viscosity and the fuel economy. The lowering of engine oil viscosity causes the reduction of friction loss which has a very close relation with the fuel economy. These results as the lowering of engine oil viscosity will be a important factor for improvement of the fuel economy and reduction of the $CO_2$ emission.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.32-38
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• 2010

The objective of the research was to study the effects a Miller cycle. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. Miller Cycle without supercharging can increase brake thermal efficiency 1.08% and reduce brake specific fuel consumption 4.58%. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency.

• International Journal of Automotive Technology
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• v.2 no.2
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• pp.53-62
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• 2001

The combination of physical models of an advanced engine control system was proposed to obtain sophisticated combustion control in ultra-lean combustion, including homogeneous compression-ignition and activated radical combustion with a light load and in stoichiometric mixture combustion with a full load. Physical models of intake, combustion and engine thermodynamics were incorporated, in which the effects of residual gas from prior cycles on intake air mass and combustion were taken into consideration. The combined control of compression ignition at a light load and sparit ignition at full load for a high compession ratio engine was investigated using simulations. The control strategies of the variable valve timing and the intake pressure were clarified to keep auto-ignition at a light load and prevent knock at a full load.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.4
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• pp.197-206
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• 2015

Recently the automobile engine has been developed in achieving the high performance, fuel economy, and emission reduction. In a conventional spark ignition engine the fuel and air are mixed together in the intake system, inducted through the intake valve into the cylinder, and then compressed. Under normal operating conditions, the combustion is initiated towards the end of the compression stroke at the spark plug by an electric discharge. Following inflammation, a flame develops and propagates through this premixed fuel-air mixture. Therefore the state of mixture is very important in the combustion and emission characteristics. In this study the combustion and emission characteristics were tested and analyzed with changing the mixture composition and engine operating parameters in order to improve the combustion and performance in engine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.37-45
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• 2003

The diesel engines was invented a little more than one hundred years ago and has ever since been developed for better fuel economy, increased power and smaller size. Thanks to its fuel economy, the diesel engine is today the dominating prime mover in many applications, such as smaller power plants, commercial ships, trains, trucks, buses and all kinds of mobile construction machinery. As engine for passenger cars, the diesel engine is steadily increasing its share of the market. However, its versatility and, consequently, large prevalence have led to environmental demands to its exhaust emissions, noise and vibration. This paper deals with the noise aspects of diesel engine designs of the so-called low speed two-stroke type installed in most large ships.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.401-402
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• 2002

Diesel engines have many sliding parts with solid body contact. For example, a piston-ring and a cylinder bore, a valve and a valve-seat, a cam and a valve tappet. These parts have a severe wear problem. during engine life times. During these times, the valve tappet has abnormal wear such as scuffing and pitting due to a high hertzian contact stress between the cam and the tappet. Excessive wear problems frequently occur to both the cam and the tappet. To solve these problems, we developed an advanced wear resistant tappet. The developed tappet consisted of a hard-metal wear part and a steel body. To increase a bonding strength, those two parts, were directly bonded to each other. Also to decrease a bonding temperature, we developed the composition of Ni-binder materials in the hard metal. To estimate the wear characteristics of the newly developed tappet, we performed wear tests and engine dynamo tests in order to compare them with a conventional Fe-base tappet. As a result, the newly developed tappet has better wear characteristics than those of the conventional tappet. In addition, we performed a 100,000km field-test, and the newly developed tappet showed much improved wear resistance.