• Journal of Energy Engineering
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• v.14 no.3 s.43
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• pp.173-179
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• 2005

Fuel injection system has more benefits in power, fuel consumption and emission than carburetor system even in high speed small engine. Up to date fuel injection system is used in motor car but is not used in motorcycles in Korea. EFI (Electronic fuel injection) system which has ECU can control precise fuel supply to variable RPM in engine. The purpose of this study is the investigation of effects of fuel injection system to improve the engine performance and efficiency in variable revolution of high speed small engine which is 4 Valves SOHC single cylinder engine used in motorcycle.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.151-158
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• 1998

The screw compressor is first invented by a Swedish engineer, Alf Lysholm in 1934. Since then, the development of the screw compressor idea for industrial applications has been continued by the Swedish research organization Svenska Rotor Maskiner, often identified by its initials SRM. The first industrial application of the machine was marketed as an air compressor in the 1950s. The screw compressor which is a positive displacement type compressor compresses gases by the rotation of a pair of mating rotors. The operation of this compressor is entirely rotary and dynamically in balance. Also there is no need for any valve mechanism and there exists less mechanical wear between the parts compared to the conventional reciprocating compressors. Due to these prominent features, the screw compressor has been rapidly spread into the air compressor market replacing the conventional reciprocating compressors and begun to be applied as a refrigerant compressor since the 1960s. In this work, the operation principle of the screw compressor is described in brief and the major design parameters affecting the compressor performance are classified. The international research trend in screw compressor development is introduced and the current situation in our country is described.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2075-2080
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• 2013

A Coolant core for Range Extender engine has been developed using CFD technique. Coolant by-pass has been added to the improved model to reduce temperature near and between exhaust valve. Due to the increased coolant flow-rate both around the second cylinder block and between exhaust valves, improved model shows no significant stagnant flow compared with base model. Finally, the improved model shows improved heat transfer coefficients near exhaust valves, and 5% reduced pressure-drop through the coolant core. Reduced pressure-drop may increase the fuel efficiency by reducing the load of a coolant pump.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.277-284
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• 2013

In this paper, the ventilating and heating system of T-103 trainer aircraft were investigated and redesigned to improve its poor performance. The ventilation system of the trainer was designed to increase the mass flow rate of fresh air by using air intake valves. The flow-in air through the air intake valve is supplied to the cabin by the ram effect of aircraft and the propeller. And the additional heating system was installed to improve the temperature of the cabin inside. The wasted heat from the exhaust gas of the engines was used as heat source of the additional heating system by installing an heat exchanger around the exhaust nozzle. The additional fresh air and the heated air enter the cabin via two ducts mounted under the instrument panel and behind the pedal in the cabin. The additional ventilating and heating system can be controlled by the first pilot and the secondary pilot individually using the control knob equipped separately. After mounting the additional ventilating and heating system, evaluations such as inspection of parts and component, ground run-up test, in-flight test, user test, etc. were conducted. The result of the tests was sufficient to meet the requirements of the manuals, and the pilots were satisfied with the additionally mounted systems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.517-524
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• 2011

A vortex tube is a device that can separate small particles from a compressed gas or separate a compressed gas into hot and cold flows. We experimentally analyzed the energy-separation characteristics of a vortex tube with a diameter of 10 mm. We measured the energy-separation characteristics of the vortex tube for different inlet air pressures, orifice diameters, and tube lengths. The orifice diameter and inlet pressure are important for the vortex tube design and operation. The tube length has a small effect on the energy-separation performance. Maximum energy separation occurs for a vortex tube with Dc = 0.7 D and L = 16 D.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1109-1114
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.11
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• pp.1069-1076
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT(Quantitative Feedback Theory) is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. Tracking specification is satisfied with upper and lower bound tolerances on the steep response of the system to the reference signal. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.4
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• pp.1-20
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• 1997

The automotive industry as the major industry of the nation has affected both society and economy since the automobile was invented, and the main technique that help to performance improvement of the automobile has been developed. But, the painting technique lags behind the main technique of the automobile because that was neglected. Specially, we can say that in case of the painting technique of the automobile of our nation is so weak situation. After we changed the injecting pressure, the composition ratio (paint, hardener, thinner) and the injecting flow rate from spray-gun by PDPA, we studied the character of the injecting velocity and droplet size, and found the fittest condition. So, we got the following result to help mending paint technique of automobile surface. We could know the following fact from the experiment result. When it does mending paint of automobile, there is most suitable that to inject the paint as injecting pressure 200∼300 kPa and to inject the ratio of paint 10 : 1 : 1 when the fluid adjective knob valve spay-gun is open full.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.70-75
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• 2010

Compressed air represents an energy source and an force-transmission medium for brake systems on medium-heavy and heavy-duty commercial vehicles. However, one disadvantage is the tendency of air to absorb moisture in the form of water vapor. This water vapor condenses once the air, which is heated during compression, cools back to ambient temperature upon emerging from the air compressor. The resulting condensation assumes the form of moisture in pneumatic lines, air tanks, cylinders and valve assemblies and can have negative consequences for the brake system and vehicle safety. The pneumatic systems on today's vehicles are equipped with air dryers, in which the supplied air is dried according to the adsorption principle. In the systems, the compressed air flows through a granular desiccant with molecular sieves which captures the water molecules.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.128-135
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• 2008

EGR(exhaust gas recirculation) is considered as a most effective method to reduce the NOx emissions. But high EGR tolerance is always pursued not only for its advantages of the pumping loss reduction and fuel economy benefit in Gasoline-Hybrid engine. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR on fuel efficiency, combustion stability, engine performance and exhaust emissions. With optimal EGR rates, the fuel consumption was improved by 4%. This improvement was achieved while a reduction in NOx emissions of 75% was accomplished. Increase of EGR gas temperature causes the charge air temperature to affect the knock phenomenon and moreover, the EGR valve lift changes for the same control signal.