• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.308-311
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• 2004

Nowadays, plastic industry has needed to produce parts that require high precision and quality. To make a high precision and quality part, before injection molding, plastic material is investigated about their properties such as shrinkage, warpage, etc. In this study, experiments were conducted with PA6(polyamid) to figure out shrinkage behavior according to three type aspect ratio of samples. The injection speed that affects on shear rate, molecular orientation within plastic part was determined as main variable of experiment. As a result of experimental study, part shrinkage had a tendency to be decreased by increasing injection speed and aspect ratio of samples.

• 한국분무공학회지
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• 제15권2호
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• pp.67-73
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• 2010

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail direct injection system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors with different electric driving characteristics, including solenoid-driven and piezo-driven type. Namely three common-rail injectors with different electric current wave were investigated in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. As this research results, it was found that pilot injection of common-rail system was effected by rate of injection with different electrical characteristic for injector driving.

• 한국분무공학회지
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• 제20권3호
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• pp.195-201
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• 2015

This study discusses a fuel injector test bench containing a mechanical type fuel supply system for heavy duty diesel engine. The main focus of this study was to evaluate the design stability of the test bench, which basically measures the injector durability of a multi-hole heavy duty injector by using pure diesel as a test fuel. In this experiment, diesel spray was controlled by a specially designed control box and all the experiments were carried out to measure e.g. fuel injection pressure and fuel injection quantity to understand the injection status which is interlinked with the stability factor of total test bench design. Also, the durability test was performed to understand the heavy duty operation lastingness of the designed system and the flow rate of the installed distributor pump in the fuel supply system of this studying test bench was compared with LO-1 and LO-2 pump. The results of the above mention tests revealed that the injector test bench design and control system can serve the purpose for heavy duty injector.

• 한국자동차공학회논문집
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• 제4권4호
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• pp.46-57
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• 1996

The direct injection stratified charge(DISC) engine enhances the fuel tolerance and the antiknock tendency. This enhanc3d antiknock tendency allows use of a higher compression ratio which results in higher thermal efficiency. But its actual utilization is prevented by high emission combustion time and wall quenching will be the main causes of increasing unburned hydrocarbons in DISC system. In order to solve this problem, small aount of hydrogen was added to the charging air or injected fuel. The effects of hydrogen addition were examined experimentally by radial fuel injection using a pancake-type constant volume bomb. In case of the hydrogen addition to the charge of air, the combustion the amount of hydrogen. In case of the hydrogen addition to the fuel, the combustion pressure was significantly increased.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.500-510
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• 1996

A Direct injection -mixing total -flow -control sprayer was developed and evaluated . The system provided precise application rates and minimized operator exposure to chemicals as well as providing a possibility for recycling container so f unused chemicals that can causes environmental contamination. Chemicals were metered and injected proportionally to the diluent flow rate to provide constant concentrations. The main diluent flow was varied in response to changes in travel speed. Experimental variables of the sprayer were the control interval, the sensitivity of flow regulating valve, the tolerance of control object and the sensitivity of the injection pump system. The optimal performance of the flow control system was with an average response time of 8.5 sec at an absolute steady state of error of 0.067 L/min (0.8% of flow rate). The average response time of the injection rate was -0.53 sec and the coefficient of variation (CV) of concentration was 3.2%.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.175-181
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• 2008

The technologies of mold design, manufacturing, injection molding process and computer aided engineering(CAE) are developed rapidly with the growth of plastic product market. Injection molding process optimum design can not be easily determined. This study was determined factors and levels which carried out to analyze an influence of narrow pitch BGA socket warpage and performed investigating the main effect and interaction effect between factors using design of experiment. The result of this paper is injection time and packing pressure are affect on narrow pitch BGA socket warpage at injection molding.

• 한국분무공학회지
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• 제15권1호
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• pp.25-30
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• 2010

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail direct injection system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors with different electric driving characteristics, including solenoid-driven and piezo-driven type. Namely three common-rail injectors with different electric current wave were investigated in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. As this research results, it was found that pilot injection of common-rail system was effected by rate of injection with different electrical characteristic for driving the injector.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.931-937
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• 2004

Simultaneous filling is a goal in plastic injection mold that has multi cavities. The moldings which have not been filled at the same time have undesired faults such as dimension inaccuracy, residual stress, law mechanical strength, etc. The best way to simultaneous fill is to be injected in a geometrically balanced runner system. In a general processing, however, in balanced runner system mold, filling imbalance would be observed in cavities. These phenomena result from molten polymer's characteristics and circumstances in balanced runner. In this study, the degree of filling imbalance (DFI) was defined for showing rate of filling imbalance in geometrically balanced injection mold that has 8 cavities. Before the main experiment, an injection molding simulation was conducted to know a pattern of filling imbalance with Moldflow software. There were somewhat differences between results of experiment and simulation about the filling imbalance. The reason for the difference was that the software have not concerned about a situation in a real flow channel. It was also investigated how the injection speed affected on filling imbalance in the experiment.

• Journal of Advanced Marine Engineering and Technology
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• 제17권4호
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• pp.49-62
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• 1993

It has been a principle research topic on the diesel engine development to increase the efficiency and the performance of engine to satisfy the user's needs for high reliability and durability. However, recently with the worldwide concerns at the global climate change and environmental protection, the main target in the diesel engine research has been changed to solve the exhaust emission problem in order to satisfy the strict emission regulations. To reduce the pollutant for the diesel engine, the researchs on the combustion chamber is the most important and has to be performed first of all. The diesel fuel injection system plays major role to air-fuel mixing process and influences engine output, themal efficiency, reliability, noise, and emissions. The experimental studies were conducted by varying the various parametric conditions and the results were campared with the computation and calculated results by using the fuel injection simulation program developed during previous research. From the experiments, the matching technique of a fuel injection pump and nozzle was conducted to understand under the various parametric conditions. Also, the relations between needle lift and wave propagation characteristics in high pressure pipe were examined. The basic design data from the experimentations and computation works would be applied to actual design works of diesel fuel injection system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.119-122
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• 2002

In general, Liquid Injection Thrust Vector Control(LITVC) is accomplished by injecting a liquid into the supersonic exhaust flow through holes in the wall of the propulsion nozzle. This injection flow field is highly complicated and detailed flow physics associated with the secondary flow injection should be known far the practical design and use of the LITVC system. The present study aims at understanding the LTTVC flow field and obtaining fundamental design parameters for LITVC. The experimentations were performed in a supersonic blow-down wind tunnel. Compressed, dry air was used for both the main exhaust and injection flows but the pressures of these two flows were controlled independently. The location of the injection holes was changed and the pressures of the two streams were also changed between 2.0 and 15.0 bar. The effectiveness of LITVC was discussed in details using the results of the pressure measurements and flow visualizations